Comparative Analysis of Viability, Regeneration, and Functional Contributions of Cryopreserved Adipose-Derived Components: An Experimental Study.

The use of cryopreserved adipose tissue for soft tissue augmentation is common, but unpredictability of fat graft viability remains a limitation. Adipose-derived stem cell (ADSC) and stromal vascular fraction (SVF) have been introduced to enhance viability and improve the survival of transplanted fat tissue. To investigate whether supplementation with ADSC or SVF improved the survival of cryopreserved fat grafts. The cryopreserved fat grafts were treated with ADSC, SVF, or normal saline in 30 six-week-old male nude mice to test whether ADSC and SVF could improve the survival of the transplanted fat tissue. The authors examined the weight, volume, and histological features of each group (n = 10) at 8 weeks after transplantation to evaluate the survival of the fat tissue. There was no difference between the control and SVF groups with respect to weight, volume, and histological findings. However, the ADSC group showed a significant increase in weight and volume compared with the control and SVF groups. Histological examination showed that the ADSC supplementation improved the quality of the transplanted fat grafts. Taken together, these results suggest a potential clinical utility of ADSC but no advantage of SVF in facilitating cryopreserved fat transfer.

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Background: Intra-articular injection of adipose-derived stem cells (ASCs) has shown promise for improving symptoms and cartilage quality in the treatment of osteoarthritis (OA). However, while most preclinical studies have been performed with plastic-adherent ASCs, most clinical trials are being conducted with the stromal vascular fraction (SVF), prepared from adipose tissue without prior culture. Purpose: To directly compare clinical outcomes of intra-articular injection with ASCs or SVF in patients with knee OA. Study Design: Cohort study; Level of evidence, 3. Methods: The authors retrospectively compared 6-month outcomes in 42 patients (59 knees) receiving intra-articular injection with 12.75 million ASCs and 38 patients (69 knees) receiving a 5-mL preparation of SVF. All patients had Kellgren-Lawrence grade 2, 3, or 4 knee OA and had failed standard medical therapy. The visual analog scale (VAS) pain score and Knee injury and Osteoarthritis Outcome Score (KOOS) at baseline and 1, 3, and 6 months after injection were considered as outcomes. Outcome Measures in Rheumatology–Osteoarthritis Research Society International (OMERACT-OARSI) criteria were also used to assess positive response. A repeated measures analysis of variance was used for comparison between the treatment groups. Results: No major complications occurred in either group. The SVF group had a higher frequency of knee effusion (SVF 8%, ASC 2%) and minor complications related to the fat harvest site (SVF 34%, ASC 5%). Both groups reported improvements in pain VAS and KOOS domains. Specifically, in the ASC group, symptoms improved earlier (by 3 months; P < .05) and pain VAS decreased to a greater degree (55%; P < .05) compared with the SVF group (44%). The proportion of OMERACT-OARSI responders in the ASC group was slightly higher (ASCs, 61%; SVF, 55%; P = .25). Conclusion: It was observed that both ASCs and SVF resulted in clinical improvement in patients with knee OA, but that ASCs outperform SVF in the early reduction of symptoms and pain with less comorbidity.

The abilities of intracavernous injection of autologous stromal vascular fraction (SVF) and adipose-derived stem cells (ADSCs) to facilitate recovery of erectile function in a rat model of cavernous nerve (CN) injury were compared. Forty male Sprague-Dawley rats were randomly divided into four groups: sham and control groups (intracavernous injection of phosphate-buffered saline), SVF group (intracavernous injection of SVF), and ADSC group (intracavernous injection of ADSCs). Rats in the latter three groups underwent bilateral CN injury prior to injection. The evaluation of erectile function and histomorphometric studies were performed 4 weeks after injection. The ratio of maximal intracavernous pressure to mean arterial pressure was significantly lower in the control group than in the sham group (0.18 vs. 0.56, p < .001). Intracavernous injection of SVF (0.36, p = .035) significantly improved erectile function compared with that in the control group, whereas the ADSC group (0.35, p = .052) showed marginally significant improvement. The smooth muscle/collagen ratio, smooth muscle content, number of neuronal nitric-oxide synthase-positive nerve fibers, and expression of von Willebrand factor were significantly higher in the SVF and ADSC groups than in the control group. Expression of endothelial nitric-oxide synthase was significantly increased in the SVF group. The increases in the smooth muscle/collagen ratio and von Willebrand factor expression were larger in the SVF group than in the ADSC group. Intracavernous injection of SVF or ADSCs was equally effective in recovering penile erection in a rat model of CN injury.

Adipose-derived stem cells (ADSCs) and the stromal vascular fraction (SVF) promote nerve regeneration. Biodegradable nerve conduits are used to treat peripheral nerve injuries, but their efficiencies are lower than those of autologous nerve grafts. This study developed biodegradable nerve conduits containing ADSCs and SVF and evaluated their facial nerve regenerating abilities in a rat model with a 7-mm nerve defect. SVF and ADSCs were individually poured into nerve conduits with polyglycolic acid-type I collagen as a scaffold (ADSCs and SVF groups). The conduits were grafted on to the nerve defects. As the control, the defect was bridged with polyglycolic acid-collagen nerve conduits without cells. At 13 weeks, after transplantation, the regenerated nerves were evaluated physiologically and histologically. The compound muscle action potential of the SVF group was significantly higher in amplitude than that of the control group. Electron microscopy showed that the axon diameter of the SVF group was the largest, followed by the ADSC group and control group with significant differences among them. The SVF group had the largest fiber diameter, followed by the ADSC group and control group with significant differences among them. The ADSC group had the highest myelin thickness, followed by the SVF group and control group with significant differences among them. Identical excellent promoting effects on nerve regeneration were observed in both the ADSC and SVF groups. Using SVF in conduits was more practical than using ADSCs because only the enzymatic process was required to prepare SVF, indicating that SVF could be more suitable to induce nerve regeneration.

This study aimed to evaluate the effects of the stromal vascular fraction (SVF) and adipose-derived stem cells (ADSCs) on cartilage injury in an osteoarthritis (OA) rat model. Sodium iodoacetate (3 mg/50 μL) was used to induce OA in the left knee joint of rats. On day 14 after OA induction, 50 μL of SVF (5 × 106cells), ADSCs (1 × 106 cells), or 0.9% normal saline (NS) was injected into the left knee-joint cavity of each group. The macroscopic view and histological sections revealed that the articular cartilage in the NS group was damaged, inflamed, uneven and thin, and had hyperchromatic cell infiltration. Notably, the cartilage surface had recovered to nearly normal and appeared smooth and bright on day 14 in the SVF and ADSC groups. Additionally, the white blood cell counts in the SVF and ADSC groups were higher than those in the NS group on day 14. Plasma IL-1β levels on days 7 and 14 were reduced in the SVF and ADSC groups. These results indicated that both SVF and ADSC treatments may assist in articular cartilage regeneration after cartilage injury. Cell therapy may benefit patients with OA. However, clinical trials with humans are required before the application of SVF and ADSC treatments in patients with OA.

Adipose-derived stem cell (ADSC)-enhanced fat grafting, including enrichment with stromal vascular fraction (SVF) and adipose-derived regenerative cells (ADRCs), has been increasingly used to improve fat graft survival and regenerative outcomes in reconstructive and aesthetic plastic surgery, yet long-term safety, efficacy, and mechanistic understanding remain variably reported. This systematic review aimed to evaluate real-world clinical evidence on the long-term safety, volume retention, and functional outcomes of ADSC-, SVF-, and ADRC-enriched fat grafting across aesthetic and reconstructive indications. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, comprehensive searches of PubMed, Scopus, Web of Science, and the Cochrane Library identified 3158 studies, of which 12 met the inclusion criteria, encompassing randomized controlled trials and prospective non-randomized clinical studies assessing ADSC-, SVF-, or ADRC-assisted fat grafting with reported outcomes related to graft survival, clinical function, aesthetic performance, or safety. Across studies, ADSC and SVF enrichment generally improved volume retention compared with conventional fat grafting, with several randomized trials demonstrating graft survival rates of 60-80% at three to six months, and ADSC-assisted grafts consistently enhanced dermal regeneration by improving collagen organization, skin texture, and elastic fiber architecture. In reconstructive applications, SVF therapy reduced digital ulcers and pain in patients with systemic sclerosis, while ADRC-assisted grafting alleviated symptoms of breast cancer-related lymphedema despite limited objective limb-volume reduction, and patient satisfaction was high across all enrichment techniques. Safety outcomes were favorable, with no increase in infection, cyst formation, fat necrosis, or oncologic recurrence across follow-up periods of up to four years. Overall, ADSC-, SVF-, and ADRC-enriched fat grafting appear to offer meaningful improvements in graft survival, skin quality, and functional recovery with a strong safety profile across diverse clinical indications, although methodological heterogeneity and limited long-term data support the need for standardized, regulated, and mechanistically informed clinical protocols, as well as larger, long-term randomized trials to optimize techniques and guide clinical use.

BackgroundFat grafting is one of the most effective treatments for soft tissue restoration and augmentation. Adipose-derived stem cells (ASCs) supplementation is one of the foremost concerns to improve its efficiency. There have been several studies aiming at adipose-derived mesenchymal stem cells in fat grafting, but no relevant bibliometric research has conducted.MethodsArticles about fat grafting and ASCs were retrieved in Web of Science Core Collection (WoSCC). Using VOSviewer 1.6.10.0 (Leiden University, the Netherlands) and CiteSpace 6.1.R2 (Drexel University, USA), the information of national distribution, institutions, journals, authors and keywords were evaluated and calculated.ResultsA total of 1166 papers in the field of ASCs in fat grafting were retrieved from 2002 to 2021. The USA produced the most articles, and the top 2 productive institutions were all from the USA. Researchers and institutions conducting ASCs in fat grafting research have shown a widespread and close connection. Plastic and Reconstructive Surgery published the most article on ASCs in fat grafting, and professor Rubin Peter is the most productive author. The top 10 references with the highest LCS mainly focused on applying ASCs to assist fat transplantation in plastic surgery. The most cited keywords formed 4 clusters, and “mesenchymal stem,” “mesenchymal stromal cell,” “stromal vascular fraction” and “long term” were the most recently trending keywords.ConclusionsThis article provides a summary of the current research status focusing on fat grafting and ASCs. More efforts will be made to promote the application of ASCs in fat grafting.Level of Evidence VThis journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

We read with tremendous interest the article entitled “Quality and Quantity–Cultured Human Mononuclear Cells Improve Human Fat Graft Vascularization and Survival in an In Vivo Murine Experimental Model.”1 The article is thought-provoking, and we would like to add some additional perspectives that might extend the current results. First, an interesting finding is that stromal vascular fraction did not increase vessel density but enhanced the weight persistence of fat by week 7; therefore, the authors thought stromal vascular fraction might function not through angiogenesis. However, some studies have demonstrated that stromal vascular fraction could enhance vessel growth. Matsumoto et al.2 implanted free fat supplemented with stromal vascular fraction in mice and found that stromal vascular fraction–assisted fat exhibited more microvasculature than the non–stromal vascular fraction fat. In a mouse model of wound healing,3 stromal vascular fraction significantly increased the density of CD31-positive vessels compared with the control mice. One explanation might be that the authors extracted stromal vascular fraction from middle-aged individuals rather than younger ones, which would possibly limit the capacity of stromal vascular fraction to support microvascular networks. Allison L. Aird’s team4 implanted collagen constructs into mice that contained either young stromal vascular fraction (from a 4-month-old rat) or old stromal vascular fraction (from a 24-month-old rat). Their findings demonstrated that mean total vessels, perfused vessels, and mature vessels were reduced in the old stromal vascular fraction group compared with the young group, which showed lower vessel formation and maturation capacity of stromal vascular fraction from older animals. Therefore, we expect to witness identical results in the stromal vascular fraction group from younger individuals. Second, the results did not show the discrepancy in adipose persistence rate between the quality and quantity–cultured mononuclear cell (MNC-QQ) group and the stromal vascular fraction group by 7 weeks after injection, which may shadow the future study of MNC-QQ. The MNC-QQ technique requires 1 week of culture in vitro, while stromal vascular, which also promotes fat retention in free fat grafting, barely needs any cell separation or culture. Therefore, we anticipate more data to show the superiority of MNC-QQ. Because MNC-QQ promoted higher vessel density compared with stromal vascular by 7 weeks and a previous study showed grafted fat underwent degeneration, regeneration, and stabilization until 3 months to 1 year or even more,5 we think that it might help to yield positive results if authors enlarge the volume of grafted fat tissue or elongate the observation time to 3 months. Third, we are thankful for the authors’ effort to prove that quality and quantity culture improved the proangiogenic capacity of peripheral blood mononuclear cells; however, we question the efficiency of MNC-QQ to enhance free fat grafting, considering the amount of blood. The experimenters drew 150 ml of venous blood to separate human mononuclear cells. However, since the exact details of the experiments are unknown, we calculate that 150 ml of blood supported only 0.25 g of free fat in about 40 mice [peripheral blood mononuclear cells group (16) + MNC-QQ group (16) + additional testing (8) = 40], which means 15 ml of venous blood promoted the survival of merely 1 g of fat. Patients might hesitate to choose MNC-QQ, especially those who require large-volume fat grafting. Hence, researchers should take into account the dose-response relationship between peripheral blood and grafted fat. DISCLOSURE The authors declare that they have no conflicts of interest to disclose. Ao Fu, M.D.Yiye Ouyang, M.D.Xingyi Du, M.D.Xiaomu Ma, M.D.Chunjun Liu, M.D., Ph.D.Plastic Surgery Hospital (Institute)Peking Union Medical CollegeChinese Academy of Medical SciencesBeijing, People’s Republic of China

The Fourth World Congress of the International Society of Plastic Regenerative Surgeons: Another Successful Scientific Forum for Regenerative Surgery.

The adipose-derived stromal vascular fraction (SVF) is composed of a heterogeneous mix of adipose-derived stem cells (ADSCs), macrophages, pericytes, fibroblasts, blood, and other cells. Previous studies have found that the paracrine effects of SVF cells may be therapeutic, but their role in osteoarthritis treatment remains unclear. This study aimed to investigate the therapeutic effect of SVF cells on chondrocytes. Chondrocytes were seeded on culture plates alone (control) or cocultured with SVF or ADSCs on cell culture inserts. After 48 h of coculture, chondrocyte collagen II, tissue inhibitors of metalloproteinases-3 (TIMP-3), and matrix metalloproteinases-13 (MMP-13) messenger RNA (mRNA) expression levels were evaluated using reverse-transcription polymerase chain reaction, and the transforming growth factor-β (TGF-β) levels in the supernatant were measured using ELISA. Immunohistochemical staining and flow cytometry were used to evaluate the macrophages in the SVF. These macrophages were characterized according to phenotype using the F4/80, CD86, and CD163 markers. To determine whether the Smad2/3 signaling pathways were involved, the chondrocytes were pre-treated with a Smad2/3 phosphorylation inhibitor and stimulated with the SVF, and then Smad2/3 phosphorylation levels were analyzed using western blot. The mRNA expression levels of various paracrine factors and chondrocyte pellet size were also assessed. Collagen II and TIMP-3 expression were higher in the SVF group than in the ADSC group and controls, while MMP-13 expression was the highest in the ADSC group and the lowest in the controls. TGF-β levels in the SVF group were also elevated. Immunohistochemical staining and flow cytometry revealed that the macrophages in the SVF were of the anti-inflammatory phenotype. Western blot analysis showed that the SVF increased Smad2/3 phosphorylation, while Smad2/3 inhibitors decreased phosphorylation. Smad2/3 inhibitors also reduced the expression of various other paracrine factors and decreased chondrocyte pellet size. These findings suggested that the paracrine effect of heterogeneous cells, such as anti-inflammatory macrophages, in the SVF partly supports chondrocyte regeneration through TGF-β-induced Smad2/3 phosphorylation.

Although many studies have suggested that human adipose tissue contains pluripotent stem cells, a few reports are available on stromal vascular fraction (SVF). In the present study, we evaluated the bone formation capacities of SVF. We implanted uncultured freshly isolated adipose-derived stem cells combined with demineralized bone matrix (DBM) to induce bone regeneration in a critically sized rat calvarial defect model. We used DBM (DBX(®)) and/or poly(70L-lactide-co-30DL-lactide) copolymer PLA as a scaffold. Fifty white rats were randomized to 5 different groups (n=10): (1) control, (2) DBM, (3) DBM + SVF, (4) DBM + PLA, and (5) DBM + PLA + SVF groups. After acquiring SVF, an 8-mm critically sized calvarial defect was made in each rat. Specimens were harvested at 8 weeks postimplantation and evaluated radiographically and histologically. New bone formation was qualified by hematoxylin and eosin staining and anti-osteocalcin antibody (OC4-30) immunostaining of calvarial sections. Amounts of mineralization were determined by radiodensitometric analysis. In gross appearance, the DBM + SVF and DBM + PLA + SVF groups showed more abundant bone formation than the other groups. Radiodensitometric evaluations revealed that significant intergroup differences were observed according to the Kruskal-Wallis (rank) test (P=0.030<0.05). The 5 groups show different amounts of filling of bone defects (control: 13.48%; DBM: 39.94%; DBM + SVF: 57.69%; DBM + PLA: 24.86%; DBM + PLA + SVF: 42.75%). Histological evaluation revealed that there was abundant new bone formation in the DBM + SVF and DBM + PLA + SVF groups. It was found that undifferentiated adipose-derived stem cells in the form of SVF induced new bone formation in rat calvarial defects. Accordingly, SVF offers a practical, promising candidate for regenerative tissue engineering or cell-based therapy.

Objective To observe the effect of human adipose stromal vascular fraction (SVF) derived culture supernatant protecting kidney from acute ischemia/reperfusion injury (IRI). Methods SVF was isolated and was used for the preparation of SVF derived culture supernatant named SVF conditioned medium (SVF-CM). Hypoxia/reoxygenation (H/R) injury model of renal tubular epithelial cell (HK-2) was established for cell proliferation and apoptosis assay. Thirty-two SD rats were divided into four groups randomly: SVF-CM group, SVF group, control group, and sham group. Twenty-four hours after surgery, blood sample was collected for the detection of serum creatinine (SCr) and blood urea nitrogen (BUN). Kidney tissues were retrieved for hematoxylin and eosin (HE) and immunohistochemical staining. Results Both SVF-CM and SVF could significantly enhance the proliferative capability as well as attenuate the apoptosis of HK-2, while no significant difference could be found between the two groups for cell proliferation (P=0.781) and apoptosis (P=0.921, 0.280). At 24 h after surgery, serum levels of SCr and BUN in both SVF-CM and SVF groups were significantly lower than that in control group (P=0.000). However, there was no significant difference between the two groups (P=0.993, 0.985). Tubular damage score in both SVF-CM (1.9±0.8) and SVF (1.7±0.9) groups were significantly lower than that in control group (3.3±0.7) (P=0.000). Meanwhile, the numbers of proliferating cell nuclear antigen (PCNA) positive cells in both SVF-CM [(60.86±18.39) cells] and SVF [(62.51±20.03) cells] groups were significantly higher than that in control group [(33.61±6.91) cells] (P=0.000). Additionally, the numbers of terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) positive cells in both SVF-CM [(24.73±6.82) cells] and SVF [(22.11±5.68) cells] groups were significantly lower that in control group [(45.12±7.85) cells] (P=0.000). However, no significant difference on tubular damage score, number of proliferative cells and apoptotic cells could be found between SVF-CM and SVF groups (P=0.114, 0.875, 0.197). Conclusion Administration of SVF derived culture supernatant or SVF was equally effective in promoting the structural and functional recovery of damaged kidney. Key words: Adipose stromal vascular fraction; Culture supernatant; Acute kidney injury; Ischemia/reperfusion injury

Sir: We read with great interest the article by Mou et al. entitled “Extracellular Vesicles from Human Adipose-Derived Stem Cells for the Improvement of Angiogenesis and Fat-Grafting Application.”1,2 In this study, the authors evaluated whether adipose-derived mesenchymal stem cell–derived extracellular vesicles improved fat graft survival by angiogenesis and inflammation regulation. We admire the achievements the authors demonstrated, namely, that adipose-derived mesenchymal stem cell–derived extracellular vesicles promoted the migration and tube formation of human umbilical vein endothelial cells. In addition, this study showed the vesicles attenuated the inflammation response through polarizing M2 macrophages. However, we would like to advance a few questions and perspectives. First, the authors presented that adipose granules co-transplanted with 7 μg of extracellular vesicles had a better survival retention of fat grafts. Only one dose was chosen in the experimental group. However, the results may not be enough to prove the regenerative potential of the vesicles without comparing different dosages. We would appreciate it if the authors would provide the details on the basis of concentration used in this study. Thus, we suggest that researchers should incorporate various dosages of extracellular vesicles to confirm an effective physiologic range. Second, the lipoaspirates were obtained from five women, aged 20 to 40 years. However, the authors did not provide the range of body mass index of donors. As far as we know, obesity could extend to metabolic and endocrine dysfunction; these adipose-derived stem cells express higher mRNA levels of several proinflammatory cytokines compared with healthy adipose-derived stem cells.3 Therefore, the production and bioactivity of the exosomes for obesity adipose-derived stem cells would be negatively influenced. The recent advances in our understanding of adipose-derived stem cells have made it essential to identify the donor source of cells to ensure consistent therapeutic efficacy. Third, fat grafts were harvested and analyzed from four randomly selected mice of each group in this study. Nevertheless, Eto et al. revealed that adipocytes were most susceptible to death after fat grafting under ischemic conditions, whereas adipose-derived stromal cells can remain viable for 3 days and had regenerative activities.4 In addition, according to the research by Kato et al., CD34+ proliferating adipose stem/progenitor cells were seen at 1 to 4 weeks, but the majority of proliferating cells were M2 macrophages.5 Therefore, the timing of observation might not be accurate enough for us to see the dynamic remodeling impacted by extracellular vesicles after fat grafting. In conclusion, we are very grateful that the authors demonstrated that adipose-derived mesenchymal stem cell–derived extracellular vesicles had proangiogenic and antiinflammatory effects on nonvascularized fat grafting. This work laid a great foundation for further research and clinical application in this field. We expect further findings that the adipose-derived mesenchymal stem cell–derived extracellular vesicles may possess regenerative potential for innovative medical products in clinical translation. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication.

Chronic UVB exposure accelerates skin aging by inducing oxidative stress and inflammation, leading to dehydration, reduced collagen density, and impaired epidermal and dermal integrity. Stem cell-based therapies, including the use of the stromal vascular fraction (SVF) and adipose-derived stem cells (ASCs), have emerged as promising approaches for skin regeneration. This study evaluated the therapeutic effects of SVF and ASCs on UVB-induced skin damage. The mice were exposed to UVB irradiation (290-310 nm) for eight weeks to establish a photoaging model. Following UVB exposure, the SVF or ASCs were injected into the dorsal skin, and the skin samples were analyzed. UVB exposure significantly reduced skin hydration (-26%), decreased collagen density, and led to a decrease in the thickness of the epidermal and dermal layers. The SVF and ASC treatments improved skin hydration, enhanced extracellular matrix remodeling, and increased collagen density. Both treatments reduced oxidative stress by decreasing reactive oxygen species (ROS) levels, with SVF-treated samples exhibiting increased BMAL1 expression. SVF and ASCs also promoted angiogenesis and lymphangiogenesis. A reduction in macrophage infiltration and a shift in polarization from the proinflammatory M1 phenotype to the anti-inflammatory M2 phenotype were also observed in the SVF and ASC groups, with ASCs exhibiting stronger immunomodulatory effects. The SVF and ASCs each displayed distinct therapeutic advantages in skin tissue restoration. These findings highlight the potential of the SVF and ASCs as therapeutic strategies for UVB-induced skin aging, warranting further clinical investigation.