Table 1.
Different types of hydrogels applied in supporting folliculogenesis and oogenesis
| Specie Family | Hydrogel and supplementary additives | Cell source | Stages of follicles and oocytes development | Main results | Ref. |
|---|---|---|---|---|---|
| Primate (Human) | Collagen type IX FSH | Primary follicles (29±11 years old) |
Ovulation | Histological findings from embedded follicles in collagen gel exhibited an increase in granulosa cell layer numbers and oocyte size in ~40% of the follicles within 24 h. TEM images indicated the formation of cellular outgrowths around growing follicles. Also, more extended culture led to follicle deterioration and oocyte release. | (26) |
| Primate (Human) | Collagen type I FSH | Fully and partially isolated follicles (30±7 years old) | - | Electron microscopy studies revealed detachment of partially isolated follicles from collagen. According to histological examinations, the fully isolated follicle size and granulosa cell numbers increased on collagen gel. Moreover, fully and partially follicles deteriorated within 24 h cultured on top of collagen. | (27) |
| Primate (Human)+ Rodent (Hamster) | Bacteriological Agar FSH | Pre-antral follicles (isolated from premenopausal human ovaries) +Large pre-antral follicles (7-8 layers of granulosa cells and thin theca cells) | Antral | Culturing human follicles for 168 h and their analysis by morphological test showed developia2ng pre-antral follicles to the antral stage creating an antral cavity with germinal vesicle oocyte. | (28) |
| Primate (Human) | Sodium alginate | Pre-antral follicles (25-35 years old) | Pre-antral | All 9 follicles incubated in an alginate-based 3D system after 7 days showed an increase in size with a survival rate of 90% according to morphological and histological assays. | (29) |
| Primate (Human) | Sodium alginate FSH | Secondary follicles (16-39 years old) | Antral | The 3D alginate hydrogel supported follicle development from early secondary to the antral stage containing healthy and growing oocytes with proper steroid production through hormonal and morphological investigations. | (30) |
| Primate (Human) | Sodium alginate | Primordial and primary follicles (21-31 years old) | Primordial and primary | Cryopreservation of follicles embedded in alginate beads with two other cryoprotectants (dimethyl sulfoxide (ME2SO) and ethylene glycol (EG)) showed better follicles preservation for 1.4 M ME2SO compared to 1.5 M EG after thawing and 7 days of culture according to viability and morphological analysis. | (31) |
| Primate (Human) | Alginate FSH | Primordial follicles and ovarian cortex tissue (2-41 years old (median age: 20.5 years)) | Pre-antral and antral |
Histological and morphological findings indicated that encapsulation and culture of ovarian cortical fragments in alginate hydrogel maintained the survival, differentiation, and growth of follicles up to growing pre-antral and antral stages within several weeks while the isolated follicles degenerated during 24 h. | (32) |
| Primate (Human) | Alginate FSH | Multilayered secondary follicles (72.7% younger than 20 years old, 20.5% between 20-30 and 6.8 % older than 30) | Antral MII oocytes |
The hydrogel system supported follicles developing from the pre-antral to the antral stage, producing meiotically competent metaphase II (MII) oocytes after in vitro maturation (IVM). | (33) |
| Primate (Human) | Alginate EGF, FSH, hCG, |
Secondary follicles (6-34 years old) | Ovulation | The alginate hydrogel system could support folliculogenesis and also the transformation accompanied with ovulation and luteinization. Follicles showed similar patterns of serum hormones identified through the menstrual cycle. | (34) |
| Primate (Monkey) | Sodium alginate FSH, LH | Pre-antral follicles (8-9 years old) | Antral | Based on the morphological result, different survival rates were seen in isolated follicles from the follicular phase of the menstrual cycle (higher) compared to those isolated from the luteal phase (lower). Follicles encapsulated in both alginate concentrations (0.5% and 0.25%) could grow and develop into the steroidogenesis phase by producing estradiol, androstenedione, and progesterone for ≤30 days. | (35) |
| Primate (Monkey) | Sodium alginate FSH | Primordial follicle (6.5, 9.5 and 12 years old) | Primordial | Utilizing various alginate concentrations, it was indicated that the follicle survival and morphology of encapsulated follicles in higher alginate concentrations (2%) were more optimal compared to softer hydrogel (0.5%) through histological assessment. | (36) |
| Primate (Monkey) | Fibrin-sodium alginate FSH | Pre-antral follicles (7–10 days postovulation) | Antral MII oocytes | Fibrin-alginate hydrogel enhanced the growth rate of pre-antral follicles and supported them to reach the small antral stage in the absence of FSH. | (37) |
| Primate (Monkey) | Fibrin-sodium alginate FSH | Primary and secondary follicles (7-14 years old) | Antral MII oocytes | The fibrin hydrogel could improve theDevelopment of only primary but not secondary follicles at week 1; however, the alginate encapsulation enhanced the growth properties of secondary follicles.. Moreover, only the fertilized oocyte from the secondary follicles reached the morula stage, while the oocyte from the primary follicle arrested without cell division. | (38) |
| Primate (Human) | PEG-fibrinogen and alginate FSH | Ovarian tissue (5–27 years old) | Primordial | PEG-fibrinogen hydrogels system supported the in vitro development of the follicles with less atretic follicles formation than alginate scaffolds. | (39) |
| Rodent (Mouse) | Collagen type I | Primordial to secondary follicles (10 days old) | Pre-antral | The 14-day culture in collagen gel matrix-maintained follicle 3D structure and follicle growth from unilaminar to multilaminar within 6 days based on morphological, and histological examinations. | (40) |
| Rodent (Mouse) | Collagen type I FSH | Pre-antral follicles (24-28 days old) | Pre-antral | Based on morphological and immunocytochemistry tests, the 3D gel-maintained follicle 3D structure and supported follicle growth and differentiation while 2D culture led to flattened follicles and caused spontaneous follicle disruption. | (41) |
| Rodent (Mouse) | Alginate-Collagen I FSH | Secondary follicles (12-16 days old) | Pre-antral | When cultivated in alginate-collagen I matrices, two-layered secondary follicles were FSH responsive, with FSH dose-dependent increases in follicle development, lactate generation, and steroid release according to histological and hormonal assessments. FSH, on the other hand, had a deleterious impact on the survival and Development of multilayered secondary follicles. | (42) |
| Rodent (Mouse) | Collagen I FSH | Primary and early secondary follicles (6 days old) | Ovulation | A multi-step follicle culture within collagen hydrogels indicated growing follicles and producing oocytes based on morphological and molecular analysis that were able to generate live birth after implantation in pseudo pregnant mice. | (43) |
| Rodent (Mouse) | Agar FSH | Early pre-antral follicles (14 days old) | Pre-antral MII oocytes | Based on the morphological assessment, in vitro growing pre-antral follicles in agar, oil, and hydrophobic ECM showed that agar led to follicular growth, although oocyte maturation percentage and oocytes reaching nuclear maturation was higher in oil culture. | (44) |
| Rodent (Mouse) | Sodium alginate FSH, EGF | Granulosa cell–oocyte complexes (12 days old) | - | The complex follicular architecture was maintained during the encapsulation confirmed through the TEM images. Besides, the granulosa cells proliferated, and the oocytes volume increased based on morphological findings. | (45) |
| Rodent (Mouse) | Sodium alginate FSH | Secondary follicles (12 days old) | Antral MII oocytes | Comparting cryopreserved and non-cryopreserved follicular culture on alginate hydrogel revealed a decrease in androstenedione levels in the cryopreservation group than in the other groups at day 12 of culture. Moreover, both individually isolated follicles or those within ovarian tissue could be successfully recovered and developed after slow-freezing and thawing | (46) |
| Rodent (Mouse) | Sodium alginate FSH | Secondary follicles (12-16 dpp) | Antral | Alginate hydrogels supported the Development of 2-layer and multi-layer secondary follicles within 12 days. Moreover, analysis of molecular markers involved in different stages of folliculogenesis for follicles grown in vitro compared to those grown in vivo showed 60% similarities among gene patterns during four days. | (47) |
| Rodent (Mouse) | Alginate FSH | Primary and early secondary follicles (isolated based on average initial diameter (70, 80, 90, and 100 μm)) | Antral | Co-culture of encapsulated follicles in alginate hydrogels with mouse embryonic fibroblasts (MEF) supported follicles survival and growth, which developed antral cavities within 14 days while culturing follicles without MEF resulted in cell degeneration within 6–10 days confirmed via morphological analysis. | (48) |
| Rodent (Mouse) | Alginate Insulin, IGF | Ovarian tissue | - | Adding insulin and IGF (potent proliferative factors) in culture media where ovarian tissue culturing in alginate hydrogels led to decreased follicular integrity with formation of the hyperplastic ovarian surface epithelium. | (49) |
| Rodent (Mouse) | Alginate FSH, hCG |
Primary follicles (12 days old) | Antral | The multiple cultured follicles in alginate hydrogels were survived and developed into the antral cavity formation stage, which contained meiotically competent gametes. | (50) |
| Rodent (Mouse) | Alginate FSH | Late primary and early secondary follicles (8-12 days old) |
Antral MII oocytes | The growth of encapsulated late primary and early secondary follicles was increased with antral cavities formation in the feeder-free medium containing αMEM/F12 (1:1) supplemented with fetuin, ITS, and FSH according to morphological assessments. | (51) |
| Rodent (Mouse) | Alginate FSH, Ascorbic acid | Primary and secondary follicles (7–10 days old) | Antral | The survival and growth of primary follicles were improved when they were cultured in a 3D system (alginate hydrogel) co-cultured with MEF and supplemented with ascorbic acid (50 μg/ml) for 18 days confirmed by morphological, immunohistological, and molecular examinations. | (52) |
| Rodent (Mouse) | Alginate FSH | Early secondary follicles (12 days old) | Pre-antral | Investigation of oxygen tension role on the early secondary follicles (110 μm) Development which were cultured on alginate hydrogel showed the close correlation between follicular survival/growth to hypoxia-mediated carbohydrate transport and metabolism (glycolysis). | (53) |
| Rodent (Mouse) | Sodium alginate hCG, Panax ginseng extract (PGE) | Pre-antral follicles (14 days old) | Pre-antral | Encapsulated follicles in sodium alginate showed variable growth rates and oocyte maturation depending on the concentration of PGE, demonstrating enhanced follicular function and development at the concentration of 100 μg/mL of supplemented PGE. | (54) |
| Rodent (Mouse) | Alginate FSH, EGF, hCG | Secondary follicles (18 days old) | Ovulation | The alginate hydrogel system could support folliculogenesis and also the transformation accompanied with ovulation and luteinization. Most of the cultured murine follicles ovulated in response to hCG. | (34) |
| Rodent (Mouse) | Alginate FSH, EGF, hCG | Secondary follicles (16 days old) | Ovulation MII oocytes | The percentage of MII oocytes for follicles encapsulated in alginate-based hydrogel was the highest (85%) on day 6 while this value increased for cultured follicles to a terminal diameter of 300–350 μm (93%) . | (55) |
| Rodent (Mouse) | Alginate FSH | Multilayered secondary follicles (16 days old) | Antral MII oocytes | The follicle growth, survival, and functions of encapsulated follicles in alginate beads were affected by the exposure levels of doxorubicin (DOX). Higher DOX concentration (200 nM) led to DNA damage and apoptosis, while the number of MII oocytes was increased at 20 nM DOX. | (56) |
| Rodent (Mouse) | Alginate Sodium alginate FSH, LH, EGF, hCG | Primary follicles (10-12 days old) | Antral | When compared to follicles cultivated in groups of 5, encapsulated follicles in groups of 10 demonstrated increased levels of survival, growth, and steroidogenesis. | (57) |
| Rodent (Mouse) | Alginate FSH, EGF, hCG | Pre-antral follicles (12-14 days old) | Ovulation MII oocytes | The 3D alginate-based system could support pre-antral follicles development outside of the body and approximately could recapitulate the in vivo situation which is useful as a model system for female reproductive toxicity testing system- | (58) |
| Rodent (Mouse) | Fibrin-alginate FSH, EGF, hCG | Multilayered secondary follicles (15-16 days old) | Antral MII oocytes | The encapsulation of both freshly harvested and vitrified follicles in alginate preserved the 3D structure of follicles. Moreover, alginate hydrogel supported folliculogenesis from multilayered secondary stage (day 0) to antral stage (day 8). | (59) |
| Rodent (Mouse) | Animal origin-free extracellular matrix-derived (ES) & alginate FSH, EGF, hCG | Two-layered secondary follicles (12 days old) | Antral MII oocytes | Based on morphological and hormonal assessments, interpenetrating fibrin–alginate matrices support follicle growth with a higher number of meiotically competent oocytes compared to either fibrin or alginate hydrogel. | (60) |
| Rodent (Mouse) | Pre-antral follicles (11-14 days old) | Ovulation MII oocytes | ES-hydrogel and alginate hydrogel could support follicle development. However, the pseudo-antrum formation, cumulus-oocyte complexes, MII oocyte, spindle rate, and E2 production level were higher in ES-hydrogel than 2D and alginate hydrogel groups. | (61) | |
| Rodent (Mouse) | Extracellular matrix-derived hydrogels (fibronectin, collagen, and laminin) & matrigel FSH, activin-A | Pre-antral follicles (14 days old) | Antral | Matrigel system could maintain the 3D structure of follicles for 7 days. Moreover, the matrigel system containing activin-A increased follicle growth, survival rate and formed antral space. | (62) |
| Rodent (Mouse) | Chitosan & alginate FSH, hCG | Pre-antral follicles (12 days old) | Antral MII oocytes | The chitosan-based culture system could support the growth of the follicle with a higher survival rate, follicle diameter, and chromosome alignment compared to alginate group. | (63) |
| Rodent (Mouse) | Polyethylene glycol (PEG) FSH, EGF, hCG | Immature secondary follicles (14-15 days old) | Antral MII oocytes | Applying trifunctional cross-linking peptides to 4-arm polyethylene glycol (PEG) hydrogels improved network formation and supported in vitro ovarian follicle maturation. | (17) |
| Rodent (Mouse) | Polyethylene glycol (PEG) FSH, EGF, hCG | Early secondary and pre-antral follicles (14 days old) | Antral MII oocytes | Comparing different gel softness (as reflected in swelling ratio) impacts on in vitro growth of follicles showed the swelling ratio above 21.4 resulted in better oocyte maturation than other levels. However, the highest competence to blastocyst formation was identified at 20.6 | (64) |
| Rodent (Mouse) | ECM binding peptide-functionalized polyethylene glycol (PEG) FSH, EGF, hCG | Secondary follicles (2-14 days old) | Antral MII oocytes | The PEG hydrogels functionalized with extracellular matrix (ECM)-sequestering peptides significantly enhanced follicle survival, growth, and maturation of ovarian follicles compared to the bioinert PEG hydrogel. | (65) |
| Rodent (Mouse) | RGD-modified dextran hydrogel FSH, EGF, Activin A | Immature ovary freagments (14 dpp) | Antral MII oocytes | By establishing an ECM-mimetic bioactive microenvironment to assist folliculogenesis in a 3D ovarian tissue culture platform, RGD-modified dextran hydrogels were capable to provide physical support as well as promote follicle expansion through in vitro culture system. Oocytes grown on RGD-modified dextran hydrogels were fertile and produced blastocysts. | (66) |
| Bovidae (Bovine) | Collagen FSH, LH, E2, bFGF, EGF | Primary follicles (50–70 mm) | Antral | Morphological results indicated increases in follicles diameter. Molecular findings showed the expression of follicular maturation markers was significantly altered and the antrum formation rate of follicles increased in presence of hormonal treatment | (67) |
| Bovidae (Goat) | Agar FSH, IGF-1 | Primary and secondary follicles | Antral | According to histological and morphological findings, agar culture-maintained follicle 3D structure and facilitated Development into secondary and antral follicles. Oocyte growth was observed and theca lamina and zona pellucida were formed. The survival rate of secondary follicles was ~7 times more than primary follicles. | (68) |
| Bovidae (Caprine) | Alginate FSH, LH, 17β-estradiol, EGF, IGF-1 | Pre-antral follicles (1-3 years old) | Antral MII oocytes | Culturing pre-antral follicles in a 3D hydrogel fabricated with different concentrations of alginate revealed that more morphologically normal follicles developed in stiffer hydrogel (0.5% and 1% alginate); however, follicles on the softer hydrogel (0.25%) showed higher levels of estradiol and progesterone with an enhanced rate of meiotic resumption compared to stiffer alginate hydrogel (0. 5% and 1%). | (69) |
| Bovidae (Caprine) | Fibrin–alginate FSH, LH, 17β-estradiol, EGF, IGF-1 | Multilayered secondary follicles (≥200 μm) (1-3 years old) | Antral MII oocytes | The fibrin–alginate hydrogel supported follicles growth and maturation up to producing parthenotes. | (70) |
| Suidae (Pig) | Collagen FSH | Pre-antral follicles (containing oocytes of 70-89.5 μm in diameter) | Antral MII oocytes | The morphological assessment showed increasing in follicles diameter. Based on molecular analysis, progression to metaphase II was observed in 40% of oocytes that were over 110 μm in diameter. | (71) |
| Suidae (Pig) | Collagen type I FSH, IGF-1 | Pre-antral follicles (12-15 weeks) | Antral | Follicles cultured for 30 days in collagen-coated 24-well plates by morphological assessment showed maintaining their 3D structure and oocyte viability. Follicle diameter increased while 29% of follicles formed an antrum. | (72) |
| Canidae (Dog) | Alginate FSH, LH | Pre- and early antral follicles (6 months-5 years old) | Antral | The alginate hydrogel supported the development of encapsulated follicles. Evaluation of physical (alginate rigidity) and hormonal influences (FSH concentration) of microenvironment on in vitro growth of follicles indicated that lower alginate concentration and increasing FSH amount stimulate in vitro follicle growth confirmed by hormonal and morphological assays. | (73) |