Exosomes in aging and age-related disorders: mechanisms, therapeutic potentials, and challenges

Abstract

Aging is accompanied by a gradual decline in physiological resilience and an increased risk of chronic diseases collectively known as age-related disorders, including neurodegeneration, cardiovascular disease and osteoarthritis. Exosomes nano-sized extracellular vesicles have emerged as critical mediators in the aging process and related pathologies. By moving bioactive cargo such as proteins, lipids and mRNAs exosomes facilitate intercellular communication and modulate processes central to aging, including inflammation, immune response, senescence, and tissue repair. Exosomes contribute to “inflamm-aging,” influence stem cell function, and reflect age-associated molecular alterations, positioning them as potential biomarkers for early diagnosis and disease monitoring. Understanding dual role of exosomes as both contributors to aging and platforms for intervention offers new avenues for promoting healthy longevity and mitigating the burden of age-associated diseases. Also, their inherent stability, low immunogenicity, and capacity for targeted delivery make exosomes promising candidates for therapeutic applications in regenerative medicine and anti-aging interventions. This review synthesizes current knowledge on exosome biogenesis, composition, and functional roles in aging and age-related diseases. We discuss emerging evidence supporting their use as diagnostic and prognostic tools and their potential in cell-free therapies aimed at modulating age-related decline. Despite their promise, several challenges impede clinical applications. Addressing these limitations will be essential to fully harnessing the therapeutic potential of exosomes in aging. Notwithstanding these obstacles, exosomes exhibit significant potential for personalized and combinatorial therapies. Understanding the dual role of exosomes as both contributors to aging and tools for its modulation may open new avenues for interventions to promote healthy longevity.

Introduction

Aging is a multifactorial biological process marked by the gradual decline of physiological functions and increased vulnerability to a wide range of chronic diseases, collectively referred to as age-related disorders. These include cardiovascular diseases, neurodegenerative disorders like Alzheimer’s and Parkinson’s, osteoarthritis, musculoskeletal degeneration, and cognitive decline. As global life expectancy rises, the prevalence of these conditions places increasing stress on healthcare systems and impairs the quality of life for older individuals. Therefore, understanding the fundamental mechanisms of aging and discovering novel therapeutic approaches are critical for promoting healthy longevity and mitigating the societal burden of age-related [1]. In this context, exosomes have emerged as a promising focus in geriatric and regenerative medicine. Exosomes are small extracellular vesicles (30–150 nm in diameter) secreted by various cell types [2–4]. They originate from the endosomal system and are released through the fusion of multivesicular bodies with the plasma membrane. These vesicles carry a rich cargo of proteins, lipids, messenger RNAs, non-coding RNAs, and microRNAs (miRNAs), enabling them to serve as key mediators of intercellular communication [5–7]. By facilitating the transfer of molecular signals, exosomes influence various physiological and pathological processes, including inflammation, senescence, immune response, and tissue regeneration, all of which are integral to the aging process [8]. The importance of exosomes in aging is multifaceted. First, they modulate systemic inflammation, a key hallmark of aging often referred to as “inflamm-aging” [9]. Second, they are implicated in the regulation of stem cell function and regenerative capacity—crucial processes that decline with age. Furthermore, they can carry age-altered bioactive molecules and serve as biomarkers for diagnosing and monitoring age-related conditions [10]. Finally, exosomes may be harnessed as therapeutic agents or delivery vehicles for anti-aging treatments due to their biocompatibility and capacity for targeted transport of therapeutic molecules.

Exosomes: biological properties and mechanisms

The biological properties of exosomes stem from their unique biogenesis and diverse cargo. Exosomes are formed through the inward budding of endosomal membranes, generating multivesicular bodies (MVBs) within cells. These MVBs fuse with the plasma membrane to release exosomes into the extracellular environment. This biogenesis is tightly regulated and determines the composition of the exosomal cargo, which includes proteins (e.g., tetraspanins, heat shock proteins), nucleic acids (DNA, mRNA, and various non-coding RNAs), lipids (e.g., ceramides), and signaling molecules [11].

The cargo carried by exosomes reflects the physiological state of their parent cells and varies according to cell type, environmental stress, and age. For example, specific miRNAs such as miR-21, miR-29, and miR-34 have been shown to regulate genes involved in cellular senescence, oxidative stress response, and inflammation-three major contributors to aging and age-related pathologies [11]. Notably, aging alters the miRNA profile of circulating exosomes, which has diagnostic implications and may contribute to systemic aging by promoting senescence in distant tissues [12].

Exosomes play a pivotal role in intercellular communication, acting as nano-sized messengers that deliver their cargo to recipient cells through membrane fusion or endocytosis. This interaction modulates the behavior of recipient cells and has been shown to influence processes such as angiogenesis, immune modulation, neuronal plasticity, and extracellular matrix remodeling. In the context of aging, these communications can become dysregulated, contributing to chronic inflammation, impaired tissue repair, and the spread of pathological protein aggregates associated with neurodegenerative diseases [13].

Emerging research suggests that exosomes from young individuals or stem cells can reverse aging phenotypes in old tissues. For instance, injections of exosomes from young mice into aged counterparts reduced senescence markers and upregulated genes associated with telomerase activity and cellular repair [12]. Similarly, mesenchymal stem cell-derived exosomes (MSC-Exos) have shown promise in reducing oxidative stress, inflammation, and cellular aging in multiple tissue types including the kidneys, brain, and joints [14].

The functionality of exosomes also depends on post-translational modifications and lipid composition, which can be altered during aging and disease. Proteomic and lipidomic studies of exosomes from aged plasma or senescent cells reveal distinct molecular signatures that may act as both biomarkers and mediators of pathological aging processes, such as extracellular matrix degradation and chronic inflammation [15].

Together, these insights underscore that exosomes are not mere byproducts of cellular activity, but rather dynamic entities with powerful roles in regulating the aging phenotype. Their influence spans from cellular senescence to systemic metabolic changes, positioning them as both biomarkers and therapeutic vectors for age-related interventions.

The role of exosomes in mechanisms related to aging

Over the past decade, research has underscored the critical role of extracellular vesicles (EVs), particularly exosomes, in regulating aging processes [16]. Recent studies suggest that exosomes significantly influence aging and age-related diseases by modulating oxidative stress pathways, inflammatory responses, and tissue repair mechanisms [17]. Notably, exosomes exhibit a dual role in aging, with both beneficial and detrimental effects. While they contribute to tissue function decline and the propagation of aging signals, they also possess anti-aging potential by regulating cellular activities and delivering protective molecules, including those with antioxidant properties [18, 19]. Herein, we examine key mechanisms by which exosomes influence the process of cellular aging.

Oxidative stress

Exosomes, secreted by most cell types, exhibit distinct characteristics when derived from stressed, aged, or senescent cells, such as mesenchymal stem cells (MSCs), fibroblasts, and specific tissue-resident cells. These exosomes are enriched with unique cargos, including pro-inflammatory cytokines, altered microRNAs (miRNAs), and damage-associated molecules, which can propagate senescence signals and influence aging processes in neighboring cells and stem cell niches [20]. Cellular homeostasis is upset by stressors such as oxidative, inflammatory, DNA damage, metabolic, mechanical, and hypoxic stress, which causes cellular senescence. In response, cells release exosomes filled with signaling molecules that hinder tissue regeneration and relay stress signals, such as reactive oxygen species (ROS) [21, 22]. Reactive oxygen species (ROS) are highly reactive byproducts of molecular oxygen (O₂) that are more reactive than O₂. ROS include free radicals like superoxide (O₂•⁻) and hydroxyl radicals (HO•), as well as reactive molecules that aren’t radicals, like hydrogen peroxide (H₂O₂) [23]. Oxidative stress is caused by an imbalance that favors prooxidants over antioxidants, upsetting the cellular redox balance [24]. Prooxidants encourage oxidative reactions that can result in DNA lesions, particularly double-strand breaks, and protein misfolding [25]. Under stress, exosomes can impair the body’s ability to regenerate and repair, accelerating aging. By disrupting critical repair pathways, these vesicles contribute to the progression of age-associated physiological deterioration [26]. Exosomes released by senescent cells accelerate the aging of endothelial cells by increasing the production of reactive oxygen species, including superoxide and hydrogen peroxide, primarily via the activation of NADPH oxidase and mitochondrial oxidase pathways [27]. In contrast, exosomes derived from youthful, healthy cells exhibit potent anti-aging properties [28]. The molecular contents of exosomes include an intricate array of bioactive agents engineered to address oxidative stress. These vesicles convey critical antioxidant enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), which proficiently eliminate reactive oxygen species in the cells they target. [29, 30]. Beyond these primary enzymes, exosomes also deliver glutathione (GSH), antioxidant vitamins, and essential cofactors that support enzymatic antioxidant activity, equipping recipient cells with a comprehensive antioxidant defense system [31]. In aging tissues, redox disequilibrium extends beyond a mere biochemical phenomenon, operating as a sophisticated intercellular signaling network mediated by extracellular vesicles (EVs). Cells undergoing senescence or mitochondrial dysfunction modify the selection of molecular cargo and the process of exosomes biogenesis, particularly through pathways involving The endosomal sorting complexes required for transport (ESCRT) and ceramide [32]. Oxidative stress associated with aging significantly modifies the surface properties of exosomes. Exosomes from stressed cells in circulation show decreased CD63 levels, heightened acetylcholinesterase (AChE) activity, and greater reactive species content [33]. Stress further enhances selective cargo sorting, evidenced by the augmented incorporation of EphA2 in exosomes via ROS-dependent inhibition of PTP1B phosphatase, a mechanism associated with growth signaling pathways [34]. Additionally, oxidative stress enhances VEGF receptor expression on exosome surfaces, especially in retinal pigment epithelial cell-derived exosomes, which may affect angiogenesis [35]. Conversely, in environments that reduce oxidative stress, exosomes maintain typical expression of standard surface markers like CD9 and CD63, emphasizing their role as reliable indicators of exosome integrity under oxidative conditions [36]. As cells grow older, they incorporate higher levels of key antioxidant molecules, including peroxiredoxins (PRDXs), superoxide dismutase 2 (SOD2), thioredoxin 1 (TRX1), glutathione S-transferase P1 (GSTP1), and haptoglobin, into exosomes, which may help safeguard nearby cells against oxidative injury [37]. A key alteration in exosome lipid composition under oxidative stress is the accumulation of ceramide. This exosome-associated ceramide plays a pivotal role in promoting cellular apoptosis and senescence across various cell types, serving as a critical mediator in these processes. This is especially pertinent in aging, since lipidomic investigations of serum exosomes revealed that serum exosomes from older women were significantly enriched in C24:1 ceramide [38]. In elderly cells incorporating EV cargo, key redox defense systems like Nrf2 and PI3K-AKT are transformed, altering the downstream biological processes associated with aging. Such modifications regulate the cellular response to oxidative challenges, thereby affecting the development of aging characteristics [39]. Exosomes contain microRNAs that regulate genes related to oxidative stress; this regulation primarily occurs thru the inhibition of enzymes such as NOX proteins, which are responsible for producing reactive oxygen species (ROS) [40]. Additionally, circular RNAs such as circHIPK3 and circZNF609 play a protective role in cells within exosomes by modulating stress response pathways, reducing hydrogen peroxide-induced cell death [41]. Exosomes contain a varied molecular cargo with therapeutic components, such as those from mesenchymal stem cells that deliver miR-214-3p. This microRNA strengthens antioxidant defenses by decreasing CD151 levels, leading to improved pathological conditions in Alzheimer’s Disease [42]. During intervertebral disc degeneration, where increased oxidative stress promotes the production of catabolic factors, including MMP-3 and TNF-α, mesenchymal stem cell-derived exosomes offer therapeutic effects by transporting antioxidant proteins, namely Prdx-1, Gpx4, and Trap1 [43]. Furthermore, Exosomes from human umbilical cord stem cells alleviate early ovarian insufficiency triggered by oxidative stress through the activation of AMPK and the modulation of autophagic equilibrium, supporting reproductive health [44].

Inflammation

Inflammation is a phylogenetically developed defense mechanism elicited by infection or tissue trauma, characterized by the engagement and expenditure of immune cells to reinstate and uphold the organism’s overall integrity [45]. However, sustained or recurrent inflammatory responses can inflict tissue injury and foster the progression of chronic inflammatory diseases [46]. Through mechanisms like targeted apoptosis, necrosis, or excessive extracellular matrix deposition, these diseases can affect multiple organ systems and significantly impair regular bodily functions [47]. The relationship between exosomes and inflammatory responses has garnered a lot of scientific attention because of their ability to affect intricate multicellular systems and control essential biological processes (such as immunosuppression, inflammation, proliferation, differentiation, migration, and molecular transport). The body’s inflammatory processes are shaped and coordinated in large part by exosomes released by immune cells, including dendritic cells, T lymphocytes, B cells, and macrophages [48]. It is becoming more well recognized that aging, or persistent, low-grade inflammation, is a systems-level process sustained by intercellular communication. Extracellular vesicles (EVs) that transport cytokines, SASP-linked proteins, and regulatory RNAs across immune, stromal, and stem-cell niches are a key medium for that communication. In addition to changing their released cytokines, senescent and stressed cells can modify EV production and cargo, allowing EVs to integrate into the SASP and spread immunomodulatory signals or secondary senescence throughout tissues. Age-related EV remodeling has also been suggested as an emergent hallmark in and of itself. This offers a mechanistic link to the revised Hallmarks of Aging, where chronic inflammation and altered intercellular communication are explicit hallmarks [49–51]. In aged tissues, the cargo of extracellular vesicles (EVs) modulates canonical inflammatory pathways. EV-associated “inflammamiRs,” such as miR-146a, promote macrophage polarization from pro-inflammatory M1 states toward anti-inflammatory, pro-resolving phenotypes while suppressing NF-κB and NLRP3 inflammasome activity. Conversely, EVs produced under conditions of stress or cellular senescence can activate the NLRP3 inflammasome, disseminating senescence-associated secretory phenotype (SASP)-like signals and inflammasome components that perpetuate inflammation. These dual roles—suppression mediated by miR-146a versus activation driven by senescence-associated EVs—elucidate the capacity of EVs to either mitigate or exacerbate age-related inflammation. [49, 52, 53].

Tissue regeneration

In the context of tissue regeneration, exosomes are essential signaling agents that help repair and regenerate damaged tissues by coordinating and enhancing cellular processes [54]. They are essential for controlling gene expression, protein synthesis, and cellular homeostasis in recipient cells. Furthermore, they initiate vital regenerative pathways (such as AKT, ERK, STAT3, and Wnt/β-catenin) that are necessary for tissue repair processes like cell migration, proliferation, differentiation, and survival [55, 56]. In addition to fewer stem/progenitor cells, niche dysfunction and imbalanced signaling pathways also hinder tissue regeneration in aging. The biochemical and physical signals (matrix stiffness, growth factors, metabolic support) that stem cells need for self-renewal and lineage commitment are provided by stem-cell niches, which deteriorate with age. Extracellular vesicles (EVs) originating from embryonic stem cells (ESCs), young mesenchymal stem/stromal cells (MSCs), or other progenitors carry cargos (miRNAs, growth factors, and metabolic enzymes) that aid in recovering stem-cell function, rescuing niche signaling, and reactivating pathways such as AKT/PI3K, STAT3, and Wnt/β-catenin. These pathways are frequently seen to cause better differentiation, decreased senescence, and increased proliferation in aged tissues in animal, in vitro, and small clinical trials [57, 58]. By inhibiting Ccn2-mediated activation of the AKT/mTOR pathway, EVs derived from embryonic stem cells enriched in miR-15b-5p and miR-290a-5p, for instance, have been demonstrated to revitalize senescent cells in old mice, regaining more youthful transcriptome signatures and function. According to another set of research, MSC-EVs promote angiogenesis and proliferation while lowering fibrosis and inflammation by activating Wnt/β-catenin or STAT3, which improves skin repair, tendon healing, peripheral nerve regeneration, and bone repair. Framing restorative effects through these pathways connects them to the central narrative of aging, as these signaling axes are also involved in key aging markers (dysregulated intercellular communication, loss of niche integrity, and stem-cell fatigue) [59, 60].

Stem cell aging

Senescence-related phenotypes, reduced differentiation potential, and impaired regenerative capacity are frequently linked to stem cell senescence [61]. According to recent research, exosomes play a crucial part in encouraging stem cell aging through a variety of signaling pathways [62]. Senescent cell accumulation in tissues is a critical factor driving age-related disorders. Strategies designed to either remove these cells or block their detrimental secretory phenotype have demonstrated potential in diminishing symptoms associated with aging [63]. Exosomes play a central role in stem cell aging by transferring senescence-associated molecules. Studies reveal that exosomes derived from aged mesenchymal stem cells (MSCs) contain factors that promote aging in recipient cells. Specifically, exosomes isolated from the bone marrow of aged mice exhibit elevated miR-183-5p levels, which reduce bone marrow stem cell proliferation, inhibit osteogenic differentiation, and induce cellular senescence [64]. Similarly, exosomes from the muscles of aged mice show increased miR-34a expression, further accelerating aging in bone marrow stem cells [65]. Molecular mechanisms involved in the control of cellular senescence are key contributors to the aging of stem cells influenced by exosomes. In this regard, the proteins p53, p21, and p16 are markedly elevated in expression within aged mesenchymal stem cells (MSCs) compared to those from younger individuals. These proteins act as principal cell cycle regulators and are frequently utilized as defining markers in studies on cellular senescence [66]. Among the miRNAs present in exosomes from aged or senescent mesenchymal stem cells (MSCs), miR-17, miR-34, miR-146a, and miR-335-5p have been identified as important regulators of aging. Their primary role involves the inhibition of pro-apoptotic gene expression and the regulation of cellular aging mechanisms, telomere length maintenance, and circadian cycle modulation. These combined factors lead to a progressive decrease in the regenerative capacity of adult stem cells across various tissues during aging [67, 68]. On the other hand, several investigations suggest that exosomes from stem cells may function as an effective biomaterial for the development of cell-free therapies aimed at addressing aging and age-related conditions [69]. A novel study indicates that administration of antler stem cells (ASC)-secreted exosomes reduced cartilage degeneration in the OA mouse model and alleviated senescence of human stem cells [70]. In a separate study, exosomes from cordycepin-loaded dental pulp stem cells promote bone repair in aged tissues by revitalizing senescent mesenchymal stem cells and endothelial cells [71]. Additionally, research has demonstrated that by transferring SMADs, exosomes made from embryonic stem cells (ESCs) can restore the stemness of hypothalamic neural stem cells (hNSCs). Myelin transcription factor 1 (MTF1) is downregulated in this activation, which subsequently causes aged hypothalamic NSCs to activate Sirt1, NAMPT, and HIF-2 [72].

Exosome-based therapeutics for age-related diseases

The inevitable biological process of aging is marked by a steady deterioration in physiological function, which makes people more susceptible to a variety of chronic, crippling illnesses referred to as age-related disorders. These consist of metabolic dysfunctions, musculoskeletal conditions, cardiovascular illnesses, and neurodegenerative disorders, all of which have a substantial influence on quality of life and pose serious global health issues [73]. Conventional treatment methods often focus on certain routes or symptoms, which limits their effectiveness, specificity, and capacity to handle the intricate, multifaceted aspects of aging. Extracellular vehicles (EVs), in particular exosomes, have become a very promising platform for new treatment approaches against various age-related diseases in recent years [74, 75].

Exosome-based therapeutic approaches typically take two primary forms:

1. Making use of native exosomes: Making use of the natural therapeutic qualities of exosomes produced from certain cell types, especially mesenchymal stem/stromal cells (MSCs), which have strong immunomodulatory, anti-inflammatory, and regenerative capacities [76, 77]. 2. Making use of modified exosomes: Transforming exosomes into advanced drug delivery vehicles, adding particular therapeutic agents (such as proteins, siRNAs, or small compounds), or altering their surface to better target certain tissues or cells [78, 79]. The growing promise of exosome-based treatments for many important age-related disease categories will be discussed in this section. Table 1. shows the Exosome-Based Therapeutics for Age-Related Diseases

Table 1.

Exosome-based therapeutics for age-related diseases

Disease	Source	Mechanisms	Outcomes	References
Alzheimer’s Disease	• MSC exosomes • Engineered (siRNA-BACE1, catalase, ligands	• ↓Neuroinflammation (NLRP3 inflammasome inhibition) • Aβ clearance (neprilysin or BACE1-siRNA) • Oxidative-stress reduction & enhanced BBB crossing	• Restored cognition & synaptic plasticity • ↓Aβ plaques & microglial activation	[80–87]
Parkinson’s Disease	• MSC exosomes • Engineered (miR-124, catalase, dopamine/GDNF)	• M2 microglial shift (miR-124 → NF-κB/MAPK inhibition) • Dopaminergic neuron support • Oxidative stress protection	• Improved motor function & neuron survival • ↓Neuroinflammation	[88–95]
Myocardial Infarction	• MSC/CPC/EPC exosomes • Engineered (miR-22, VEGF, drugs)	• Anti-apoptotic (↑Bcl-2/Bax → ↓cytochrome c & ↓caspase-3) • Pro-angiogenic (VEGF, miR-19a/210/132 via PI3K/Akt	• ↓Infarct size • Enhanced neovascularization & function	[96–101]
Heart Failure	• MSC/CPC/EPC exosomes • Engineered (anti-fibrotic miRNAs)	• Anti-apoptotic & pro-angiogenic • ECM remodeling & ↓fibrosis	• Improved ventricular function • Reduced fibrosis	[96–102]
Atherosclerosis	• MSC exosomes • EPC exosomes (miR-126)	• M2 macrophage polarization • Endothelial repair (SPRED1/RGS16 ↓) • Plaque stabilization	• ↓Plaque size • Improved vascular integrity	[103–107]
Osteoarthritis	• MSC exosomes • iPSC/chondrocyte exosomes	• Anti-inflammatory (IL-10, TSG-6) • Cartilage synthesis (SOX9/COL2A1 via PI3K/Akt) • ↓Synovitis	• Cartilage repair & matrix restoration • ↓Inflammation	[108–112]
Sarcopenia	• MSC exosomes	• Satellite-cell rejuvenation (myomiRs) • ↑Protein synthesis & ↓inflammation	• Enhanced muscle regeneration	[113–115]
Osteoporosis	• MSC exosomes	• ↓Osteoclastogenesis (miR-21a-5p → PTEN inhibition) • ↑Osteogenesis (BMP2/Smad & Wnt/β-catenin)	• ↑Bone formation & density	[116–122]
Type 2 Diabetes	• MSC exosomes	• Restore insulin signaling (IRS-1/Akt → GLUT4) • β-cell protection & proliferation (miR-26a/PTEN/mTOR)	• Better glucose tolerance • Expanded β-cell mass	[123–128]
Obesity	• Adipo-exosomes (miR-122/192) • MSC exosomes	• Pathogenic: PPARα ↓ (→ insulin resistance) • Therapeutic: p-STAT3 → M2 → beiging via cAMP/PGC-1α	• ↓Adipose inflammation • Improved metabolic profile	[129–132]

EVs’ potential as a treatment for aging and regeneration. Extracellular vesicles (EVs), particularly those derived from young or healthy stem/progenitor cells, have been shown in numerous studies to act as cell-free regenerative therapeutics by transferring bioactive cargo (miRNAs, proteins, and metabolites) that counteract aging deficits. For instance, injecting young small EVs (sEVs) into elderly mice increased their lifespan, reversed senescent phenotypes in various tissues, and improved metabolic dysfunction by upregulating mitochondrial renewal pathways and PGC-1α. Nature Exosomes derived from human umbilical cord MSCs (hucMSC-EVs) have been shown to enhance fibroblast proliferation, promote collagen I deposition, decrease oxidative stress and mitochondrial damage, and lessen UVB-induced cellular senescence in the context of skin aging [133, 134].

Beyond the skin, EV-based treatments have also been explored in the context of age-related diseases. In a comprehensive review, Sanz-Ros et al. (2022) suggested that EVs regulate tissue regeneration in various organs and demonstrated that several animal model studies document tissue repair (e.g. kidney, liver, and heart) mediated by EV cargo modifying signaling pathways like Wnt, IGF, AKT/PI3K, and anti-oxidative axes. Additionally, the “dual role” of EVs in age-related diseases is highlighted by Putri et al. (2025), wherein beneficial EVs counteract the pathological transfer of harmful molecules [135, 136]. EV isolation/purity heterogeneity, inconsistent cargo potency characterization, immunogenicity, biodistribution issues (e.g., off-target uptake in liver/spleen), and dose consistency are all significant obstacles to translation, even in the face of encouraging preclinical data. The young sEV lifespan extension study, in particular, employed weekly systemic injections, which might not be easily applicable to humans [133].

Neurodegenerative disorders (Alzheimer’s, Parkinson’s, etc.)

The gradual loss of neuronal structure and function is a hallmark of neurodegenerative illnesses like Alzheimer’s disease (AD) and Parkinson’s disease (PD), which are often associated with the buildup of misfolded proteins and persistent neuroinflammation [137]. One major barrier to getting treatments into the brain is the BBB. Exosomes are a particularly appealing treatment option for these debilitating illnesses because of their innate capacity to traverse the blood-brain barrier [138, 139].

Alzheimer’s disease (AD) is characterized by the buildup of neurofibrillary tangles made of hyperphosphorylated tau protein within cells and the extracellular deposition of amyloid-beta (Aβ) plaques [140]. Exosomes have tremendous therapeutic value even if they have been linked to the possible spread of harmful proteins like tau and Aβ [141].

Due in large part to the exosomes and other substances they produce, Mesenchymal Stem Cells (MSCs) are well recognized for their neuroprotective and anti-inflammatory properties [142]. Exosomes produced from MSCs have been shown in preclinical models to aid in AD pathogenesis. In AD mouse models, for example, intravenous delivery of MSC-exosomes has been demonstrated to restore synaptic plasticity, recover cognitive impairments, decrease neuroinflammation (e.g., microglial activation), and diminish Aβ deposition [80, 81]. At the molecular level, MSC-derived exosomes decrease neuroinflammation by blocking the NLRP3 inflammasome pathway in microglia. This results in a more permissive environment for synaptic repair and Aβ clearance by preventing the assembly of the NLRP3-ASC complex, blocking caspase-1 activation, and reducing GSDMD-mediated pyroptosis and IL-1β release [81–83].

The transfer of certain miRNAs (e.g., miR-21, miR-146a) that control pathways associated with inflammation or enzymes that contribute to the breakdown of Aβ, such neprilysin, is often credited with the therapeutic benefits [80, 84].

Exosomes that have been modified to convey particular therapeutic cargo directly to the brain are known as engineered exosomes. For instance, after systemic treatment, exosomes containing siRNA targeting BACE1 (beta-site amyloid precursor protein cleaving enzyme 1), a crucial enzyme in the synthesis of Aβ, have effectively decreased Aβ levels in AD mice models [85]. Fig. 1 shows the role of mesenchymal stem cell-derived exosomes in a mouse model of AD. Additionally, exosomes that have been modified to exhibit targeting ligands on the outside, such as the rabies virus glycoprotein peptide, can improve brain delivery and target certain populations of neurons [86]. Oxidative stress is a major factor in AD pathogenesis, and exosomes that transport enzymes like catalase have also showed promise in lowering it [87].

Fig. 1.

This schematic illustrates the therapeutic potential of mesenchymal stem cell (MSC)-derived exosomes in ad models. MSC-exosomes, enriched with miR-21, miR-146a, and neprilysin, target microglia and neurons to mitigate ad pathogenesis. In microglia, exosomes inhibit the NLRP3 inflammasome pathway by blocking NLRP3-ASC complex assembly, suppressing caspase-1 activation, and reducing GSDMD-mediated pyroptosis and IL-1β release, thereby decreasing neuroinflammation. Additionally, exosomal miRnas and neprilysin promote amyloid-beta (Aβ) clearance and restore synaptic plasticity. Engineered exosomes carrying siRNA against BACE1 reduce Aβ production

The decline of dopaminergic neurons in the substantia nigra and the buildup of α-synuclein aggregates, also known as Lewy bodies, are the main characteristics of Parkinson’s disease (PD) [143]. Exosomes are linked to the transmission of pathogenic α-synuclein from cell to cell, much as in AD [144]. But they also provide therapeutic opportunities.

In PD models, MSC-exosomes have shown neuroprotective benefits. They may lower neuroinflammation, enhance motor function, and shield dopaminergic neurons from damage caused by neurotoxins (such as in MPTP or 6-OHDA models) [88]. Neurotrophic substances, anti-inflammatory cytokines, and miRNAs that support survival of neurons and inhibit microglial activation are probably among the cargo in discussion [142]. By blocking phosphorylation of ERK1/2, p38, and JNK and stabilizing IκBα, miRNAs enriched in these exosomes, like miR-124, target the C/EBPα/MAPK signaling axis in microglia, downregulating NF-κB-mediated transcription of pro-inflammatory genes and causing microglia to adopt an M2 phenotype [89, 90]. Additionally, VEGF/VEGFR2 signaling mediates their pro-angiogenic action in brain microvascular endothelial cells, activating downstream PI3K/Akt and ERK1/2 pathways that support endothelial survival, proliferation, and the development of new vessels [91, 92].

It has been shown that exosomes designed to transport catalase shield dopaminergic neurons from oxidative stress brought on either neurotoxins or α-synuclein [93]. In PD models, it has been investigated to modify microglial polarization into an anti-inflammatory phenotype by delivering certain miRNAs, such miR-124, via exosomes [94]. Investigation is now being conducted on the possibility of loading exosomes with medications like as dopamine or GDNF (glial cell line-derived neurotrophic factor) and directing them precisely to the substantia nigra [95]. Fig. 2 shows different functions related to miR-124 in microglial and endothelial cells.

Fig. 2.

In microglia, miR-124 inhibits the C/EBPα/MAPK signaling axis by suppressing phosphorylation of ERK1/2, p38, and JNK, and stabilizes IκBα, downregulating NF-κB-mediated pro-inflammatory gene transcription, promoting M2 polarization. In brain microvascular endothelial cells, exosomes activate VEGF/VEGFR2 signaling, triggering PI3K/Akt and ERK1/2 pathways to enhance angiogenesis

Cardiovascular diseases (CVD)

Age is a significant risk factor for CVD, which continues to be the world’s largest cause of death [145]. Complex pathologies such as inflammation, ischemia, cardiomyocyte mortality, and unfavorable tissue remodeling are present in disorders including myocardial infarction (MI), heart failure, and atherosclerosis. Exosomes generated from many cell types, particularly stem/progenitor cells, are prospective therapeutic agents since they are essential for cardiovascular homeostasis and repair [102].

In preclinical models of MI, exosomes produced from MSCs, cardiac progenitor cells (CPCs), and endothelial progenitor cells (EPCs) have shown notable cardioprotective benefits [96, 97]. These exosomes may decrease the size of infarcts, prevent cardiomyocytes from dying, decrease inflammation, encourage the growth of new blood arteries, and enhance cardiac function when given after myocardial infarction [98]. The transfer of pro-angiogenic molecules (like VEGF), anti-apoptotic proteins, and certain miRNAs (like miR-19a, miR-210, and miR-132) that control important pathways related to inflammation, vascularization, and cell survival is primarily responsible for the beneficial outcomes [96, 99, 100]. By raising the Bcl-2/Bax ratio in cardiomyocytes, hucMSC-exosomes control the balance of mitochondrial apoptosis regulators, stabilizing mitochondrial membranes, inhibiting cytochrome c release, and lowering caspase-3-mediated apoptosis after myocardial infarction [98, 101]. The methyl CpG–binding protein 2 (Mecp2) in cardiomyocytes is directly downregulated by miR-22, which is abundant in exosomes from ischemically preconditioned MSCs. This derepression of pro-survival genes further prevents the mitochondrial apoptotic cascade, hence reducing infarct size and fibrosis [99].

Many CVD occurrences are caused by atherosclerosis, which is defined by fatty buildup and inflammation in the artery wall. Exosomes may play two functions in atherosclerosis: they may mediate therapeutic benefits in addition to aiding in the production of plaque [103]. By influencing macrophage polarization toward an anti-inflammatory M2 phenotype and preventing smooth muscle cell proliferation, MSC-derived exosomes have been shown to decrease atherosclerotic plaque size and stabilize plaques [103]. Exosomes containing certain miRNAs, such as EPC-derived miR-126, can inhibit inflammatory signaling in endothelial cells and encourage endothelium repair [104]. Moreover, MSC-derived exosomes transport miR-126 to macrophages and endothelial cells, where it suppresses SPRED1, a negative regulator of Ras/ERK. This leads to an M2-skewed macrophage phenotype, increased eNOS activation, and greater ERK1/2 phosphorylation, which in turn promotes endothelium repair [105–107]. Exosomes enriched in miR-126 that are produced from endothelial apoptotic bodies target and inhibit RGS16, eliminating its inhibitory effect on CXCR4-mediated G-protein signaling. This triggers a CXCL12 autoregulatory loop that attracts progenitor cells and promotes plaque stability [104].

In order to increase effectiveness and decrease systemic adverse effects, engineered exosomes are being investigated to transport nucleic acids or cardioprotective medications precisely to the damaged heart or atherosclerotic plaques [146]. Fig. 3 shows the role of mesenchymal stem cell-derived exosomes in MI.

Fig. 3.

A. hucMSC-derived exosomes inhibit mitochondrial apoptosis in cardiomyocytes by increasing the bcl-2/Bax ratio, preventing cytochrome c release, and reducing caspase-3-mediated cell death after myocardial infarction

Methyl-CpG-binding protein 2 (Mecp2), a repressor of pro-survival genes, is directly downregulated by miR-22 present in exosomes from ischemia-resistant MSCs. This derepression of survival genes further inhibits the mitochondrial apoptotic pathway, leading to reduced infarct size and fibrosis.

B. MSC-derived exosomes deliver miR-126 to macrophages and endothelial cells, where it suppresses SPRED1, a negative regulator of Ras/ERK signaling. This leads to enhanced Ras/ERK activation, increased eNOS activity, and improved endothelial repair. These effects contribute to stabilization of atherosclerotic plaques.

Endothelial apoptotic body-derived exosomes enriched in miR-126 target RGS16, thereby relieving its inhibitory effect on CXCR4-mediated G-protein signaling. This activates a CXCL12 autoregulatory loop that recruits progenitor cells and enhances atherosclerotic plaque stability.

Musculoskeletal disorders

Osteoarthritis (OA), sarcopenia (loss of muscle mass and function), and osteoporosis (lower bone density) are age-related musculoskeletal disorders that cause pain, weakness, and a higher possibility of fracture [147]. In the musculoskeletal system, exosomes are becoming important for tissue homeostasis and regeneration.

OA is characterized by alterations in the subchondral bone, synovial inflammation, and the gradual deterioration of articular cartilage [148]. MSC-derived exosomes have shown great potential in preclinical OA models. MSC-exosomes injected intra-articularly can decrease cartilage destruction, inhibit synovial inflammation, increase cartilage matrix formation, and shield chondrocytes from death [108]. The transfer of anti-inflammatory substances (including IL-10 and TSG-6) and certain miRNAs (like miR-140-5p and miR-92a-3p) that control inflammatory pathways and chondrocyte activity mediates these outcomes [109, 148]. Exosomes made from induced pluripotent stem cells (iPSCs) or chondrocytes themselves are also being studied [149].

By activating PI3K/Akt and ERK1/2 signaling via chondrocyte surface receptors (such as CD44), MSC-exosomes mechanistically upregulate SOX9 and COL2A1 while inhibiting p38 MAPK-driven MMP-13 production. TSG-6 further inhibits TLR2/NF-κB activation to cure synovitis. Additionally, they provide IL-10, which binds IL-10 R on synoviocytes to stimulate JAK1/STAT3 phosphorylation, therefore limiting NF-κB-dependent pro-inflammatory cytokine release [110–112]. By activating PI3K/Akt and ERK1/2 signaling via chondrocyte surface receptors (such as CD44), MSC-exosomes mechanistically upregulate SOX9 and COL2A1 while inhibiting p38 MAPK-driven MMP-13 production. TSG-6 further inhibits TLR2/NF-κB activation to cure synovitis. Additionally, they provide IL-10, which binds IL-10 R on synoviocytes to stimulate JAK1/STAT3 phosphorylation, therefore limiting NF-κB-dependent pro-inflammatory cytokine release [150, 151].

Complex alterations in inflammation, anabolic signaling, and muscle stem cells (satellite cells) are all involved in age-related muscle atrophy. Muscle atrophy can be prevented and muscle regeneration encouraged by exosomes released by myogenic cells and MSCs [113]. Exosomes from young MSCs, for example, can be able to revitalize elderly muscle stem cells. They have the ability to provide elements that promote the growth and differentiation of satellite cells, improve protein synthesis, and lessen inflammation in the muscles [114]. The significance of certain exosomal miRNAs (myomiRs) in controlling muscle mass and function is being investigated [115].

This disorder results from an imbalance between osteoblasts’ production of new bone and osteoclasts’ resorption of existing bone. Exosomes can impact bone remodeling and facilitate communication between bone cells. In preclinical models of osteoporosis, MSC-derived exosomes have been shown to decrease osteoclast activity and enhance osteoblast development and bone formation [116, 117]. Certain exosomal miRNAs, such as miR-21a-5p, that are transported from osteoclasts to osteoblasts or the other way around, have regulatory functions that can be therapeutically addressed [118]. Research is also being done on engineered exosomes that transport substances that limit resorption or encourage osteogenesis [152]. By altering the RANKL/OPG balance, which increases OPG secretion, and delivering miR-21a-5p to pre-osteoclasts, which inhibits PTEN, activates Akt, and suppresses NFATc1 expression and NF-κB activity to decrease TRAP⁺ osteoclast formation, MSC-exosomes diminish osteoclastogenesis [119, 120]. Simultaneously, exosomes transport Wnt3a or miR-21a-5p to osteoblast precursors, activating the BMP2/Smad1/5/8 pathways (increasing Smad1 phosphorylation) and Wnt/β-catenin signaling (stabilizing β-catenin and driving TCF/LEF-mediated Runx2 transcription), which leads to increased expression of osteocalcin and alkaline phosphatase for the formation of new bone [121, 122]. Fig. 4 shows the role of mesenchymal stem cells and myogenic cell-derived exosomes in musculoskeletal disorders.

Fig. 4.

This tripartite schematic illustrates the therapeutic roles of mesenchymal stem cell (MSC)-derived exosomes in osteoarthritis (oa), sarcopenia, and osteoporosis. (A) osteoarthritis (oa): MSC-exosomes, enriched with IL-10, TSG-6, miR-140-5p, and miR-92a-3p, target chondrocytes and synoviocytes. In chondrocytes, exosomes bind CD44 receptors, activating PI3K/Akt and ERK1/2 signaling to upregulate SOX9 and COL2A1. In synoviocytes, TSG-6 suppresses TLR2/NF-κB activation, and IL-10 stimulates JAK1/STAT3 phosphorylation, mitigating synovitis and pro-inflammatory cytokine release. (B) sarcopenia: msc- and myogenic cell-derived exosomes, containing myomiRs and growth factors, target satellite cells, activating mTOR signaling to enhance protein synthesis and reduce muscle inflammation, promoting proliferation, differentiation, and muscle regeneration. (c) osteoporosis: exosomes carrying miR-21a-5p and Wnt3a inhibit PTEN/Akt and NFATc1 in osteoclasts, reducing TRAP⁺ osteoclast formation, and increase opg secretion to modulate RANKL/OPG balance. In osteoblasts, Wnt3a and miR-21a-5p activate BMP2/Smad1/5/8 and Wnt/β-catenin signaling, promoting Runx2, osteocalcin, and alkaline phosphatase expression for enhanced bone formation

Metabolic disorders (e.g., diabetes, obesity)

Insulin resistance, persistent low-grade inflammation, and disruption of energy balance are hallmarks of metabolic diseases such as type 2 diabetes (T2D) and obesity, which are becoming more common as people age [153]. Exosomes have a role in the pathophysiology of these illnesses and allow inter-organ communication that is essential for metabolic control. They can also have therapeutic applications [129].

T2D is characterized by decreased insulin sensitivity in peripheral tissues (liver, muscle, and adipose tissue) and decreased insulin production from pancreatic β-cells. In diabetic mice, MSC-derived exosomes have demonstrated potential for enhancing glucose homeostasis [123]. They can lower inflammation in metabolic organs, protect β-cells from apoptosis, increase insulin sensitivity, and encourage β-cell activity or proliferation [124].

By enhancing tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and activating Akt (protein kinase B) in muscle and adipose tissue, hucMSC-exosomes mechanistically restore insulin signaling. Activated Akt then encourages GLUT4 translocation to the plasma membrane and inhibits GSK3β to increase hepatic glycogen synthesis, enhancing the absorption of glucose and storage. To maintain islet bulk, they also prevent β-cell apoptosis brought on by STZ [125, 126]. These effects seem to depend on the transmission of certain proteins and miRNAs (such miR-26a) via exosomes [126].

In recipient metabolic cells, exosomal miR-26a directly targets PTEN, releasing its inhibitory brake on the PI3K/Akt/mTOR axis. This enhances Akt/mTOR signaling to increase peripheral tissues’ absorption of glucose and promotes β-cell proliferation via mTORC1-mediated protein synthesis [127, 128].

Other cell types’ exosomes, including adipocytes or hepatocytes, are involved in metabolic crosstalk and can be modified for therapeutic purposes [129].

Chronic inflammation emanating from hypertrophic adipose tissue is linked to obesity. Through the delivery of pro-inflammatory chemicals and miRNAs to other organs, adipocyte-derived exosomes, also known as adipo-exosomes, are implicated in insulin resistance and systemic inflammation [130].

Exosomal miR-122 and miR-192 linked to obesity target and downregulate PPARα in white adipose tissue, which hinders fatty-acid β-oxidation, increases circulating free fatty acids and triglycerides, and causes insulin resistance and glucose intolerance in lean mice [130].

Exosomes, however, could potentially be used medicinally. Exosomes derived from lean adipose tissue or MSCs, for example, can aid in reprogramming inflammatory adipose tissue, lowering inflammation, and enhancing the metabolic profile in general.

Phosphorylated STAT3 is delivered into adipose tissue macrophages by ADSC-derived exosomes; p-STAT3 subsequently binds the Arg1 promoter to upregulate arginase-1, causing M2 polarization. By secreting catecholamines via tyrosine hydroxylase-dependent production, these M2 macrophages promote the beiging of white adipose depots and restore metabolic equilibrium by activating adipocyte β-adrenergic receptors to stimulate cAMP/PKA/PGC-1α signaling and UCP1 expression [129, 131]. Another possible approach is to engineer exosomes to transport miRNAs that enhance insulin signaling or anti-inflammatory drugs particularly to the liver or fat tissue [132].

As previously stated, aging is marked by a gradual deterioration in physiological function in several organ systems, which makes people more vulnerable to a wide range of chronic illnesses, such as musculoskeletal conditions, cardiovascular diseases, neurodegenerative diseases, and metabolic dysfunction [154]. Research on new therapeutic approaches has increased in an effort to prevent age-related decline and prolong life expectancy, and extracellular vesicles (EVs), especially exosomes, have become popular contenders because of their distinct biological characteristics and therapeutic potential [155]. Almost every kind of cell secretes exosomes, which move a variety of proteins, lipids, and nucleic acids (mRNAs, microRNAs, and lncRNAs) to recipient cells, serving as essential mediators of intercellular communication. They are appealing therapeutic vehicles and possible biomarkers for aging and age-associated illnesses because of their capacity to modify recipient cell function, intrinsic biocompatibility, low immunogenicity (especially if sourced properly), and ability to cross biological barriers like the blood-brain barrier (BBB) [75, 156].

Preclinical research has been very exciting, showing that exosomes exhibit anti-inflammatory, neuroprotective, and regenerative properties in a variety of age-related disease models [157]. Exosomes’ special qualities, such as their capacity to shield cargo from deterioration, their ability to pass through biological barriers like the blood-brain barrier (BBB), and their lower immunogenicity when compared to synthetic vectors or viral systems, support their growing potential as therapeutic delivery systems and diagnostic biomarkers [158]. Fig. 5 shows the role of mesenchymal stem cell-derived exosomes in cell metabolism.

Fig. 5.

MSC-exosomes carrying miR-26a enhance insulin signaling in muscle and adipose tissues via IRS-1/Akt activation, promoting GLUT4 translocation and glycogen synthesis. In obesity, ADSC-exosomes deliver p-STAT3 to macrophages, upregulating arginase-1 for M2 polarization, and activate β-adrenergic/cAMP/PKA/PGC-1α signaling in adipocytes, promoting UCP1 expression and adipose tissue beiging

Summary of key clinical trials for exosomes in aging and related diseases

With the majority of studies now in Phase I or Phase II, the clinical study of exosomes, often known as extracellular vesicles (EVs) in trial registrations, is still in its relative infancy. Rather than conclusive effectiveness, the main goals of these early-phase studies are to prove safety, tolerability, appropriate dose, and feasibility. Because of the parent cells’ well-established regenerative and immunomodulatory capabilities as well as the relative ease of obtaining and growing MSCs from a variety of sources (bone marrow, adipose tissue, umbilical cord), a sizable portion of these trials use exosomes derived from MSCs [76].

The following overview is arranged by the main categories of age-related diseases:

The main risk factor for neurological disorders is aging. Exosomes have potential as therapeutic agents as well as diagnostic biomarkers, which may identify disease-specific cargo in body fluids. A number of studies are investigating the possibility of separating exosomes from blood or cerebrospinal fluid (CSF) in order to identify biomarkers such as alpha-synuclein, total and phosphorylated tau, and amyloid-beta (Aβ) for the early detection and tracking of Parkinson’s disease (PD) and Alzheimer’s disease (AD) [159, 160]. These diagnostic investigations are important clinical applications that are opening the door for targeted therapy, even if they are not interventional trials.

Preclinical research indicates that MSC-exosomes might enhance cognitive or motor performance in animal models, remove pathogenic protein aggregates, boost neurogenesis, and lessen neuroinflammation [161].

Intravenous or intrahippocampal administration of MSC-exosomes improved synaptic plasticity, decreased plaque load, and restored memory impairments in mice with APP/PS1 transgenics and amyloid-β (Aβ) injections [162]. Moreover, the safety and effectiveness of intranasally delivered allogeneic bone marrow MSC-derived exosomes in individuals with mild-to-moderate AD were examined in one noteworthy Phase I study (NCT04388982). One non-invasive method to get around the BBB is intranasal administration [163, 164].

For increased effectiveness, researchers are also looking at modified exosomes loaded with particular therapeutic cargo (such as siRNAs that target diseased genes or neurotrophic factors), albeit these are mostly in advanced preclinical phases [139, 165]. MSC-exosomes reduced demyelination, reduced neuroinflammation, and increased regulatory T-cell populations in experimental autoimmune encephalomyelitis (EAE), which improved the disease’s clinical severity. In stroke, traumatic brain injury, spinal cord injury, and prenatal hypoxic-ischemic damage, exosome treatment has been shown to offer comparable advantages in promoting angiogenesis, neuronal survival, and functional recovery [162, 166]. The transmission of bioactive miRNAs is a crucial method by which exosomes work. Preclinical research using exosome-loaded miRNA mimics (e.g., miR124, miR7) or inhibitors (e.g., anti–miR155) has shown that neuroinflammatory pathways are modulated and neuronal survival is improved in AD, PD, and ALS models [167]. Polyethylene glycol precipitation and ultracentrifugation have been used to improve the loading of exogenous miRNAs into exosomes by electroporation or transfection (e.g., shRNA-expressing plasmids), resulting in effective packing without sacrificing vesicle integrity [168]. Exosomes provide steady circulation and precise delivery to the central nervous system by shielding miRNAs from RNase destruction [164].

In mouse PD models, preclinical research shows that MSC-derived exosomes and other stem-cell secretomes may enhance motor function, lessen α-synuclein pathology, and save dopaminergic neurons. For example, human bone-marrow MSCs (hBM-MSCs) exosomes carried matrix metalloproteinase-2 (MMP-2) that cleaves extracellular α-synuclein fibrils, reducing levels of insoluble oligomers and increasing neuronal survival in vitro and in rats with 6-OHDA lesions [169, 170]. Similar to this, exosomes derived from dental pulp and stem cells (but not larger microvesicles) prevented dopaminergic apoptosis caused by 6 OHDA. When administered intracerebrally or systemically, they also normalized the expression of striatal tyrosine hydroxylase and restored gait and motor function in models of unilateral 6 OHDA lesions. Beyond proteolytic clearance, MSC exosomes transport neuroprotective miRNAs: miR133b, which is normally downregulated in Parkinson’s disease, accumulates in MSC exosomes and, when shuttled into neural cells, increases neurite outgrowth; exosome-delivered miR124 and miR145 stimulate neuronal differentiation and increase the expression of glutamate transporters in both neurons and astrocytes. All of these results point to the potential of exosome-mediated transmission of miRNAs and proteases as a non-cellular treatment for Parkinson’s disease that may delay neurodegeneration and restore motor function [171, 172].

In models of cardiac ischemia/reperfusion (I/R) damage, MSC-derived exosomes have been demonstrated to decrease infarct size, restrict apoptosis, boost ATP levels, decrease oxidative stress, and stimulate angiogenesis [173, 174]. Similar to this, exosomes from cardiosphere-derived cells (CDCs) and cardiac progenitor cells (CPCs) exhibit cardioprotective effects by modifying inflammation and angiogenesis, preventing apoptosis, decreasing scarring, and enhancing function after myocardial infarction. These effects are frequently mediated by particular miRNA cargo, such as miR-21, miR-132, miR-146a, and miR-181b. In preclinical models, exosomes derived from embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) also show potential [175]. There are presently few focused clinical studies examining exosome treatment for CVDs, despite the strong preclinical justification and biomarker promise. The use of allogeneic MSC-derived exosomes that have been transfected with miR-124 and delivered stereotactically to treat acute ischemic stroke is being studied in the NCT03384433 study. Despite being often categorized as neurological, stroke includes substantial cardiovascular foundations and risk factors, which makes this experiment particularly important. Moreover, Exosomes produced from epicardial adipose tissue are being tested as possible therapeutic agents and biomarkers in patients with atrial fibrillation as part of the NCT03478410 research. The NCT04356300 study evaluates the safety and therapeutic effectiveness of MSC-derived exosomes given intravenously for the treatment of Multiple Organ Dysfunction Syndrome (MODS) after acute type A aortic dissection, a serious cardiovascular emergency, has been surgically repaired. The procedure calls for continuous infusion after early post-operative administration [176].

Differentiating myoblasts or MSCs produce exosomes that contain muscle-specific miRNAs (also known as “myoMirs”), such as miR-1, miR-133a/b, and miR-206. These miRNAs can lessen fibrosis and encourage myogenesis. For example, exosomal miR-206 reduces excess collagen deposition by inhibiting ribosome-binding protein 1 (Rrbp1). In muscular dystrophies (such as Duchenne and myotonic dystrophy), circulating levels of these exosomal myoMirs are changed, indicating that they could function as disease indicators [177, 178]. Alteration in exosomal cargo is linked to age-related bone loss; for example, miR-183 rises with age and stimulates osteoclastogenesis, while miR-31 from aging endothelium cells inhibits osteogenesis in BMSCs. On the other hand, in osteoporotic animals, ADSC-exosomes that overexpress miR-130a-3p or that are treated with certain decoctions (delivering miR-122-5p) have shown potential in enhancing osteogenic differentiation and bone-fat balance. By decreasing inflammation (via miR-146a overexpression) and lowering NLRP3 inflammasome activation (perhaps via miR-410), ADSC-exosomes also reduce diabetic osteoporosis [177, 179].

Innovative metabolic challenge treatments are possible because exosomes can transfer miRNAs to specific cells. Certain miRNAs (miR-106b-5p, miR-222-3p), potentially transported via bone marrow cell exosomes, have been shown in animal models to ameliorate hyperglycemia and promote pancreatic beta-cell regeneration in insulin-deficient diabetic mice. It has been shown that exosomes carrying beta-cell-secreted miR-26a enhance liver insulin sensitivity. On the other hand, exosomes containing miR-375-3p that are produced under cytokine stress can cause beta-cell death [180]. When given to thin mice, exosomes produced from the adipose tissue macrophages (ATMs) of obese mice have been shown to cause insulin resistance and glucose intolerance. This action is mediated by exosomal miRNAs such as miR-155 that target PPARγ. On the other hand, insulin resistance can be lessened by ATMs from thin mice. It has been shown that adipocyte-derived exosomes containing miR-27a cause skeletal muscle cells to develop insulin resistance. Mice that had their adipocytes’ miR-34a knocked down were shielded against diet-induced glucose intolerance [180, 181]. In diabetic rats, engineered exosomes containing miR-126-3p were effective in accelerating wound healing. By controlling MMP9 production, cardiosomes—exosomes derived from cardiac cells—carrying certain miRNAs, such as miR-455 and miR-29b, have the ability to lessen the heart fibrosis linked to diabetes in db/db animals. Another theory for the systemic effects of exercise related to metabolic health is the transfer of mitochondrial components via EVs [180, 182]. Table 2 shows the overview of Exosome Sources, Mechanisms, and Developmental Stages Across Neurological, Cardiovascular, Musculoskeletal, and Metabolic Disorders

Table 2.

Overview of exosome sources, mechanisms, and developmental stages across neurological, cardiovascular, musculoskeletal, and metabolic disorders

Category	Disease/Model	Exosome Source & Delivery	Mechanism/Key Findings	Stage/Trial ID	References
Neurological Disorders	Alzheimer’s Disease	Allogeneic BM-MSC exosomes (intranasal)	• ↑ Synaptic plasticity • ↓ Aβ plaque load • Restored memory	Phase I (NCT04388982)	[161–164]
	Parkinson’s Disease	hBM-MSC exosomes; dental-pulp MSC exosomes (i.v. or i.c.)	• MMP-2–mediated α-synuclein clearance • miR-133b/miR-124/miR-145–driven neurite outgrowth & neuroprotection • Restored motor function	Preclinical (6-OHDA rat)	[169–172]
	EAE (MS model)	MSC-exosomes	• ↓ Demyelination • ↓ Neuroinflammation • ↑ Regulatory T-cell populations • Improved clinical scores	Preclinical	[166]
	Stroke/TBI/SCI	MSC-exosomes	• Promoted angiogenesis • Enhanced neuronal survival • Functional recovery	Preclinical	[162, 166]
Cardiovascular Diseases	I/R Injury	Hypoxia-elicited MSC-exosomes	• ↓ Infarct size • ↓ Apoptosis • ↑ ATP levels • ↑ Angiogenesis	Preclinical	[173, 174]
	Myocardial Infarction	CDC/CPC exosomes	• ↓ Inflammation • ↓ Scarring • ↑ Angiogenesis • ↑ Contractile function	Preclinical	[175]
	Acute Ischemic Stroke	miR-124–transfected MSC-exosomes (stereotactic)	• Targeted neuroprotection via miR-124 delivery	Phase I/II (NCT03384433)	[176]
	Atrial Fibrillation	Epicardial adipose-tissue exosomes	• Biomarker discovery & potential therapeutic effects	Phase I (NCT03478410)	[176]
	MODS (post–Aortic Dissection)	IV-infused MSC-exosomes	• Safety & efficacy in multi-organ support	Phase I (NCT04356300)	[176]
Musculoskeletal Disorders	Muscular Dystrophies	Myoblast/MSC exosomes	• miR-1/miR-133a/b/miR-206: ↓ Fibrosis • ↑ Myogenesis • Circulating myoMirs as biomarkers	Preclinical & Biomarker	[177, 178]
	Osteoporosis	ADSC-exosomes (miR-130a-3p, miR-122-5p; miR-146a; miR-410)	• ↑ Osteogenic differentiation • ↓ Inflammation (miR-146a) • ↓ NLRP3 inflammasome activation	Preclinical	[177, 179]
Metabolic Disorders	β-Cell Regeneration	BM-MSC exosomes (miR-106b-5p, miR-222-3p)	• ↑ Pancreatic β-cell regeneration • Ameliorated hyperglycemia	Preclinical	[180]
	Insulin Sensitivity	β-cell exosomes (miR-26a)	• ↑ Liver insulin sensitivity	Preclinical	[180]
	Insulin Resistance	ATM exosomes (obese: miR-155; thin: protective miRNAs)	• Obese-ATM: induced insulin resistance • Thin-ATM: improved insulin sensitivity	Preclinical	[180, 181]
	Diabetic Wound Healing	Engineered exosomes (miR-126-3p)	• Accelerated wound closure via enhanced angiogenesis & MMP9 regulation	Preclinical	[180]
	Diabetic Cardiac Fibrosis	Cardiosomes (miR-455, miR-29b)	• ↓ Fibrosis through MMP9 modulation	Preclinical	[180, 182]

Challenges in translating preclinical findings to clinical settings

There are still major obstacles in converting promising preclinical results for exosome-based treatments in age-related diseases into safe and effective clinical applications. These difficulties include those related to clinical trial design, biological comprehension, characterization, and manufacturing. The creation, separation, and purification of clinical-grade exosomes represent a significant bottleneck. Firstly, exosome production from ex vivo stem cell sources is not expressly covered by recognized Good Manufacturing Practice (GMP) guidelines. Fetal bovine serum (FBS), which is often used in traditional cell culture, includes bovine exosomes that contaminate the finished product and increase the risk of immunological responses and animal disease transmission [178]. Cells grown under serum-free settings can create exosomes enriched in stress-related proteins, which can change their therapeutic profile, even if exosome-depleted FBS or synthetic serum-free media are alternatives. Exosomes from MSCs cultivated in HPL have been shown to impact osteogenic development in a different way than anticipated, despite the fact that human platelet lysate (HPL) provides a xeno-free alternative [183]. Second, it’s still difficult to isolate enough pure exosomes [178]. The conventional method, differential ultracentrifugation, is laborious, skill-intensive, and can result in contaminating proteins or exosome aggregation [184]. Achieving large-scale, GMP-compliant purification with consistently high yield and functionality is still evolving, even though techniques like density gradient ultracentrifugation, immunoaffinity capture, size-exclusion chromatography (SEC), and tangential flow filtration (TFF) offer improvements in purity or scalability [178, 185]. It is essential that these techniques be standardized across many labs and research projects [176, 181].

Exosomes’ intrinsic variety in size, content, and function—which changes based on the source cell type and its physiological state—makes it very difficult to characterize them for therapeutic usage [186, 187]. Because of overlapping features, it may be difficult to distinguish exosomes from other extracellular vesicles [168, 178, 188]. Strong, standardized tests to evaluate their biological efficacy and guarantee consistency are severely missing, despite ISEV recommendations recommending basic characterisation utilizing markers including ALIX, TSG101, and tetraspanins (CD63, CD81) [188, 189]. Additionally, it is unclear whether proteins or RNAs are the main therapeutic effectors [188], and functional studies and therapeutic dosing are made more difficult by the generally low copy number of particular cargo, such as miRNAs, within natural exosomes [190, 191]. Despite typically minimal toxicity observed in animal models [179], translating preclinical promise meets additional biological challenges, such as comprehensive in vivo safety screening, particularly for modified exosomes. The reticuloendothelial system’s quick removal from circulation restricts bioavailability [179, 192], and it’s still very difficult to target particular tissues and prevent off-target effects [187]. Targeting may be impacted by tactics such PEGylation, which may increase circulation [193]. It takes a thorough knowledge of in vivo mechanisms and comprehensive validation to establish the best dosage, delivery routes, and treatment regimens. Lastly, as preclinical (often rodent) models do not accurately represent human reactions, thorough clinical validation is essential [176, 179, 187]. Large-scale human trials and ongoing fundamental research are necessary, as evidenced by the paucity of current clinical trials, which frequently concentrate on related complications like stroke or kidney disease rather than primary metabolic disorders [176, 178, 194].

Discussion

Exosomes present exceptional potential as biological delivery systems for the treatment of illnesses, particularly aging-related ones. However, the transition from preclinical research to secure and efficient clinical applications is still being slowed by persistent issues with regulation, safety, biology, and production procedures. Fitting exosomes into current regulatory structures is challenging due to their complex nature, which results from a variety of cellular sources, isolation techniques, and manufacturing methods [195], thus creating major obstacles to receiving approvals from agencies such as the Food and Drug Administration (FDA) of the United States [196]. Exosomes are intricate biological entities and drug delivery systems that pose regulatory hurdles, particularly when modified to serve as carriers of therapeutic agents [197]. In the United States, these organizations are categorized as “human cell and tissue-based products” (HCT/Ps) and are bound by strict production and supervision regulations set forth by the Public Health Service Act (PHS Act) and the Federal Food, Drug, and Cosmetic Act (FD&C Act) [198, 199]. Regulatory difficulties are exacerbated by exosomes’ poor stability and quick degradation as well as the lack of established procedures for their isolation, characterization, and storage. Although lyophilization and cryoprotective agents are essential techniques for maintaining structural integrity, there are still questions about the preserved exosomes’ functional characteristics [100]. Furthermore, organizations such as ISV and ME-HAD are still creating guidelines, but full worldwide standardization has not yet been accomplished [200]. Although exosomes are less likely than whole cells to trigger immune responses from an immunological standpoint, they can nevertheless cause systemic or localized immune reactions, particularly when they come from allogeneic sources [201]. Exosomes derived from cancer cells are particularly perilous as they may have carcinogenic elements that might promote tumor proliferation or facilitate cancer dissemination [202]. The accumulation of exosomes in critical organs like the lungs, liver, or spleen may exert pressure on the reticuloendothelial system, potentially leading to unexpected immunological complications [203, 204]. Risks associated with exosomes containing genetic material include the possibility of DNA mutations, inadvertent gene silencing, or unpredictable gene expression, necessitating thorough safety evaluations. These difficulties highlight how important it is to implement production methods that adhere to Good Manufacturing Practices (GMP). To prevent contaminants like leftover DNA or non-native proteins, this entails accurately identifying the cellular sources, creating sterile cell banks, and enforcing strict quality assurance protocols [205, 206]. Despite the important role the endosomal sorting complex (ESCRT) plays in this process, we still don’t fully understand exosomes, especially in relation to how they selectively sort proteins, RNAs, and DNA fragments [207]. Recent research challenges preconceived ideas about the origins of exosomes and highlights the need for additional research by suggesting that some exosomes may be produced straight from the plasma membrane. Furthermore, it is difficult to completely understand exosomes’ function in cell-to-cell communication because their selective uptake by recipient cells from their surroundings is still poorly understood [208]. Despite these challenges, exosomes hold significant promise for combined and tailored therapeutic approaches. Advanced technologies, such as artificial intelligence and high-resolution imaging, enable real-time tracking of exosome distribution and patient responses, facilitating the development of personalized treatment strategies customized to individual patient profiles [209]. To increase the targeting efficiency of exosomes, especially when navigating barriers like the blood-brain barrier, improvements in surface modification and bioengineering techniques are essential. Validating preclinical findings requires advancing exosome engineering, standardizing manufacturing procedures, and carrying out in-depth clinical research. These programs have the potential to significantly improve treatment outcomes for a variety of disorders, particularly those associated with aging. Scientists can fully realize the therapeutic potential of exosomes and help develop innovative, effective treatment approaches by heeding recent recommendations and filling in current research gaps.

Author contributions

S.S. and S.S. conducted the literature search and contributed to the manuscript writing. P.Z. conducted the figure design. M.S.S.Z. revised the manuscript. L.A.M. as the corresponding author, managed the overall writing process and manuscript revisions.

Funding

This study was supported by Research Vice-Chancellor at Tabriz University of Medical Sciences, Iran [74289].

Data availability

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

Ethical approval

Not applicable.

Consent for publication

Not applicable.

Competing interest

The authors declare that they have no competing interests.