Commentary on: Expanded Stem Cells, Stromal-Vascular Fraction, and Platelet-Rich Plasma Enriched Fat: Comparing Results of Different Facial Rejuvenation Approaches in a Clinical Trial

This study represents an important contribution in the field of regenerative aesthetics and a major advance in our understanding of tissue regeneration for the aging face.¹ Since the early 2000s, when adipose tissue was recognized as a large reservoir of stem and regenerative cells,² clinicians began to explore the potential therapeutic applications of these cells.^3-5 In spite of 15 years of largely anecdotal literature, the field is just beginning to deliver clinical evidence that these cells, used alone or added back into fat, produce a range of treatments from soft tissue augmentation to soft tissue regeneration.

As a “believer” in the field, I have had the privilege of working closely with leading scientists, clinicians, and industry experts from around the world and have witnessed the difficulty in demonstrating the efficacy of these cell-based approaches. In part, this is related to learning the language of this new field, which is evolving and not yet standardized. In part this is related to the variability of autologous tissues which are complex and still not fully understood. What is remarkable is that we find potent pharmaceutical agents in plants and other sources, but have yet to harness the remarkable repair and immune modulation features that are present in human cells and their interactions.

Although there are numerous applications for regenerative cell-based therapies in many areas of medicine, the focus of the present report is their use in the treatment of facial aging. The first aesthetic treatment done in humans with adipocyte-derived stromal vascular fraction was performed by Cohen and Holmes in 8 patients in an IRB-approved study in 2003.⁵ At that time, two observations were made: 1) there was a more widespread effect than wrinkle augmentation alone and the texture of the surface (as well as the volume of the skin and its underlying soft tissues) was apparent at 6 months (Figure 1), but also still present 6 years after a single treatment in the one patient with long-term follow-up.⁶ Not only were deeper folds filled, but the skin surface looked better and the dermal tissues looked fuller; and 2) some degree of actual regeneration had occurred. In my opinion, this article and the previous publication⁷ by the same group corroborate these early clinical impressions and bring a histologic glimpse into what is happening in the aging skin, dermis, and fat of the face after injection with stromal vascular fraction-enriched fat, expanded mesenchymal stem cell-enriched fat, and to a lesser degree, platelet rich plasma (PRP)-enriched fat.

Figure 1.

(A) A 57-year-old woman prior to injection of nasolabial folds, radial wrinkle lines, skin of the lip, and vermilion cutaneous border with a total of 14 mL of stromal vascular fraction-enriched fat. (B) Six months following injection of stromal vascular fraction-enriched fat.

Clinicians are beginning to understand the terminology of regenerative medicine and are better prepared to understand the differences in terminology. However, to complicate the subject further, there are many different ways of isolating stem cells and stromal vascular fraction and many ways to produce PRP. Because the range of products that are now available, with more to come, clinicians need to understand both the techniques of obtaining cells and the significance of cell counts and types of cells to be able to interpret the results of different studies and the output of different devices⁸ for obtaining stromal vascular fraction (SVF), mesenchymal stem cells, and PRP's. Otherwise, on first reading, comparison between studies is extremely difficult. In the most basic terms, unless the device and processing for stromal vascular fraction and/or expanded mesenchymal stem cells and/or PRP are similar in different studies, it is impossible to really ferret out the results of treatment and make valid comparisons. What further blurs our understanding is that patients in the same age group and with the same ethnic backgrounds have large variations in total cell counts and cell profiles. Different disease processes themselves stimulate changes in resident stem cells, further confounding our understanding. For instance, certain therapeutic medications such as Tomoxifen, appears to increase resident stem cell population. Within the stromal vascular fraction is a universe of cells and growth factors and other compounds making it difficult to fully understand the mechanisms at play; we are dealing with a complex orchestra. In addition, we have very little knowledge about the correct dose of cells and what it means. Do more cells increase the potency of a treatment or is a smaller dose more effective? We are still at the beginning of our understanding in this complex field.

The present study evaluated expanded stem cells, stromal-vascular fraction, and PRP enriched fat; comparing results of these different grafts in patients who were having facial rejuvenation. Three different approaches of cell enrichment were performed prior to facelift surgery and histologic changes were analyzed 3 months after treatment. The researchers found that the use of fat plus PRP led to the presence of more pronounced inflammatory infiltrates and a greater vascular reactivity, increasing the vascular permeability and a certain reactivity of the nervous component. The addition of PRP did not improve the regenerative effect. In their previous study,⁷ the authors showed for the first time that the aging process of the skin of the human face can be changed by expanded adipose-derived stem cells or fat enriched with its SVF, obtained by centrifugation without an enzymatic process but instead by mechanical means. In this study they extended those findings, but did not find PRP to be as significant of an influence in the partial reversal of histologic changes in the skin. The authors speculated that the more intense angiogenesis seen with PRP might make it a more appealing to use in ischemic conditions.¹

What is really exciting to me about this study and the authors' prior study⁷ are that they have shown morphologic reversal of aging in elastin and collagen. It is also notable that the improvement occurred both with mechanically obtained stromal vascular fraction and culture-expanded adipocyte-derived stem cells, one of the many components of stromal vascular fraction.

In the authors' previous study,⁷ and again confirmed in the present report, “ultrastructural examination showed a modified tridimensional architecture of the reticular dermis, in which the elastic fibers, with respect to the pretreatment specimens of the same patients, appeared with a reduced diameter and with a smoother surface because of a less developed fibrillar component at their periphery. In specimens removed after treatment, the elastic fibers appeared more dissociated, with reduction in the collagenic net characterizing the pretreatment biopsy specimens, in particular, in the deepest portion of the reticular dermis. At the junction between the reticular dermis and the subcutaneous tissue, the treatment was associated with the presence of a richer microvascular bed. Treatment with expanded mesenchymal stem cells resulted in modifications of the skin, which were not significantly different from those generated by the use of mechanically obtained stromal vascular fraction combined with fat. The only detectable difference was a larger amount of adipose tissue visible at the interface between the reticular dermal end of the subcutaneous layer. The addition of PRP to fat showed less regenerative changes, but overall more intense angiogenesis.”⁷

The authors' have done a very good job pointing out the limitations of the present study and perhaps in the future they will compare mechanically obtained stromal vascular fraction to enzymatically obtained stromal vascular fraction, as presently these are two of the more promising techniques in clinical practice. Both appear to have limited alterations in cell surface structure, indicating minimal manipulation. However, from a regulatory point of view, there is a longer pathway for approval of devices that require an enzyme to obtain stromal vascular fraction. If mechanical means are shown to yield sufficient quantities of unaltered stromal vascular fraction content and cells, then this would be the preferred technique in many plastic surgery applications, but especially in aesthetics. We have done smaller comparison studies and have found that some mechanical techniques yield up to 50% of the cell counts of enzymatic digestion techniques in the same patient, which is impressive.

As a clinician working in the field of regenerative medicine I perform stromal vascular fraction-enriched fat grafts for dermal-subcutaneous regeneration. It has been my long-standing belief that the loss of the subdermal network of capillaries secondary to photo-damage leads to loss of volume in the adjacent layers of the skin, including the dermis and underlying subcutaneous fat. With atrophy of the dermis and its rete pegs, less resistance to shear force is present and increased skin laxity occurs. With reduction of blood supply, tissue nutrition is compromised and there is loss of hydration in the tissue and loss of ground substance. We have continued to work on strategies that involve placing stromal vascular fraction-enriched fat grafts as sheets of insulation or lining under the dermis at the dermal subcutaneous tissue junction, theorizing that restoring the capillary network will lead to tissue regeneration. Our technique of dermal subcutaneous tissue replacement using cell enriched fat that is “blown in like a layer of insulation” throughout the entire face has shown promise in acne scarring, perioral aging, alopecia, and aesthetic rejuvenation.^9,10 Others such as Tonnard et al¹¹ have used nanofat to restore smaller areas of tissue such as the eyelid and perioral region, which they also treat with a sharp needle intradermal fat grafting technique that further strains the fat graft into a liquid that is primarily stromal vascular fraction cells.

The authors' of the present study, in my opinion, have provided the best evidence to date that these hypotheses and approaches may be correct. The findings of angiogenesis in association with reduction of elastin fiber diameter and reduction of their surrounding collagen netting, which are two of the hallmarks of the aging process in skin, supports the fact that regeneration of tissues is plausible with these approaches.

On a more practical note, I also agree with the author's assessment that the use of autologous stromal vascular fraction obtained at the point of care, combined with a scaffold of fat parcels, makes more sense than expanded mesenchymal stem cells. As mechanical means of cell separation improve, and our understanding of dosing becomes more sophisticated, these approaches will become more and more standard and widely applied in the treatment of facial aging.

I congratulate the authors on a terrific study with excellent information for the clinician working in regenerative medicine. I am very excited to see others duplicate their work and to continue to find practical and safe means to obtain stromal vascular fraction. This study shows, for the first time in humans, actual reversal of some of the histologic signs of aging. This alone will open up many new strategies for facial and skin rejuvenation as well as for treatment of disorders of subcutaneous, dermal, and epithelial tissue. Fantastic work, please keep it up!

Disclosures

Dr Cohen is a consultant, investigator, and minor shareholder in Cytori Therapeutics, Inc. (San Diego, California).

Funding

The author received no financial support for the research, authorship, and publication of this article.