Dedifferentiation of Human Adipocytes After Fat Transplantation

Adipogenic dedifferentiation enhances survival of human umbilical cord-derived mesenchymal stem cells under oxidative stress

Mesenchymal stem cells (MSCs) serve as ideal candidates for a broad range of cell-based therapies. However, cell ageing caused by long-term in vitro expansion and poor survival after in vivo delivery greatly limits their success in preclinical and clinical applications. Dedifferentiation represents a potential strategy for enhancing the retention and function of MSCs in hostile environments. In this study, we evaluated the cell phenotype, proliferation, and differentiation potential, as well as the anti-oxidative stress ability of human umbilical cord-derived MSCs (hMSCs) manipulated with adipogenic priming and subsequent dedifferentiation. After an in vitro differentiation and dedifferentiation procedure, the resultant dedifferentiated hMSCs (De-hMSCs) displayed properties similar to their original counterparts, including immunophenotype and mesodermal potential. Upon re-induction, De-hMSCs exhibited a significantly higher adipogenic differentiation capability than unmanipulated hMSCs. Importantly, De-hMSCs showed a significantly enhanced ability to resist tert-butyl hydroperoxide (t-BHP) induced apoptosis compared to undifferentiated hMSCs. Mechanisms involving bcl-2 family proteins and autophagy may contribute to the demonstrated advantages of dedifferentiation-reprogrammed hMSCs. These results indicate that adipogenic dedifferentiation promotes adipogenesis and cell persistence, as well as preserves the stemness of human umbilical cord-derived MSCs that have been committed to the adipocytic lineage. As a unique stem cell population, dedifferentiated MSCs may represent an attractive and promising candidate for MSC-based therapy.

Enrichment of Fat Graft with Association of ASC and Nanofat in an Animal Model

INTRODUCTION

Fat graft (FG) absorption rate varies from 20 to 80% in two years. Recently, several bioengineering techniques were applied to improve FG retention rate. Numerous studies investigated the use of adipocyte-derived stem cells (ASC) as FG enrichment. However, ASC production is costly, complex, and time-consuming. In contrast, Nanofat, a combination of lipids, stem cells and growth factors, offers a faster, simpler, and more cost-effective alternative for FG enrichment.

OBJECTIVE

This study aims to compare the effects of ASC with those of Nanofat, as a viable option in FG enrichment.

MATERIAL AND METHODS

Animals were allocated in three groups: Control group (1 mL fat), ASC group (1 mL fat +1x106 ASC), and NnF group (1 mL of fat + 0.3mL NnF). These groups were subdivided in three subgroups (4, 8, and 12 weeks, n = 6/group). We performed ultrasound and macroscopic measurements for FG volume, histology and expression of healing and inflammation genes.

RESULTS

At week 12, ASC and NnF groups showed a higher retention of FG when compared to the Control group (51%, 46%, 12% respectively, p < 0.01). Fibrosis was similar in ASC and Nanofat groups. The Nanofat group showed a higher vascular density then the Control group (p < 0.05). Il-10 gene expression was higher, and Mmp9 was lower in the Nanofat group when compared to the ASC and Control groups.

CONCLUSION

This study indicates that enriching FG with both ASC and Nanofat led to an increased retention rate of the FG, suggesting that Nanofat might be a promising alternative for FG enrichment.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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 .

Biomechanics of Negative-Pressure-Assisted Liposuction and Their Influence on Fat Regeneration

Autologous fat grafting has been widely adopted in cosmetic and reconstructive procedures recently. With the emerging of negative-pressure-assisted liposuction system, the harvesting process of fat grafting is more standardized, controllable, and efficient. Each component in the system could influence the biomechanical environment of lipoaspirate. Several reviews have studied the impact of negative pressure on fat regeneration. As the initial part of the harvesting system, cannulas possess their unique mechanical parameters and their influence on lipoaspirate biomechanical characters, biological behaviors, and regeneration patterns remains unclear. Basic in vivo and in vitro studies have been performed to determine the possible mechanisms. Instant in vivo studies focus on adipocytes, stromal vascular fraction cells, fat particles, and growth factors, while in vivo grafting experiments analyze the graft retention rate and histology. Understanding the different regeneration patterns of lipoaspirate and the mechanisms behind may facilitate the choice of harvesting cannulas in clinical practice.

Conditioned Extracellular Vesicles Derived from Dedifferentiated Fat Cells Promote Bone Regeneration by Altering MicroRNAs

Background: Extracellular vesicles (EVs) derived from stem cells demonstrate significant potential in bone regeneration. Adipose tissue is regarded as a stem cell reservoir with abundant reserves and easy accessibility. Compared to adipose-derived stem cells (ASCs), dedifferentiated fat cells (DFATs) possess similar stem cell characteristics but exhibit greater proliferative capacity, higher homogeneity, and an enhanced osteogenic differentiation potential. This study is the first to examine the effect of DFATs-derived EVs on bone regeneration and elucidate their potential mechanisms of action. Methods: Primary DFATs were cultured using the "ceiling culture" method and EVs were isolated by ultracentrifugation and characterized. Experiments were performed to assess the impact of the EVs on the proliferation, migration, and osteogenesis of bone marrow mesenchymal stem cells (BMSCs). Subsequently, high-throughput miRNA sequencing was conducted on the EVs derived from DFATs that had undergone 0 days (0d-EVs) and 14 days (14d-EVs) of osteogenic differentiation. Results: The results indicated that the EVs derived from DFATs which experienced 14 days of osteogenic induction significantly promoted the proliferation, migration, and osteogenic differentiation of BMSCs. High-throughput sequencing results revealed that up-regulated miRNAs in the 14d-EVs were primarily involved in biological processes such as the Notch signaling pathway and the positive regulation of cell movement and migration. The target genes of these differently expressed miRNAs were enriched in osteogenesis-related signaling pathways. Conclusion: This study innovatively demonstrated that conditioned EVs (14d-EVs) derived from DFATs promoted the osteogenic differentiation of BMSCs via miRNAs, offering a promising cell-free therapeutic option for bone defect.

Insights into the molecular changes of adipocyte dedifferentiation and its future research opportunities

Recent studies have challenged the traditional belief that mature fat cells are irreversibly differentiated and revealed they can dedifferentiate into fibroblast-like cells known as dedifferentiated fat (DFAT) cells. Resembling pluripotent stem cells, DFAT cells hold great potential as a cell source for stem cell therapy. However, there is limited understanding of the specific changes that occur following adipocyte dedifferentiation and the detailed regulation of this process. This review explores the epigenetic, genetic, and phenotypic alterations associated with DFAT cell dedifferentiation, identifies potential targets for clinical regulation and discusses the current applications and challenges in the field of DFAT cell research.

Survival Mechanisms and Retention Strategies in Large-Volume Fat Grafting: A Comprehensive Review and Future Perspectives

INTRODUCTION

Large-volume fat grafting is emerging as a promising technique in plastic and reconstructive surgery. However, the unpredictable graft volume retention rate remains a critical challenge. To address this issue, we need a profound understanding of the survival mechanisms following large-volume fat transplantation. This review summarizes known survival mechanisms and strategies to enhance graft retention.

METHODS

This review comprehensively examines the current literature on the survival mechanisms and retention strategies in large-volume fat grafting. A thorough literature search was conducted using PubMed, Medline and Google Scholar databases, focusing on studies published from 2009 to 2023.

CONCLUSION

In the current research on fat survival mechanisms, few have focused on large-volume fat grafting. This review provides an overview of the survival mechanisms specific to large-volume fat grafting and identifies a survival pattern distinct from that of small-volume fat grafting. Additionally, we have summarized existing strategies to improve graft retention across five stages (harvesting, processing, enrichment, grafting and post-graft care), analyzed their advantages and disadvantages and identified some of the most promising strategies.

LEVEL OF EVIDENCE IV

This 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.

Enhancing Fat Graft Survival via Upregulating Autophagy of Adipocytes

BACKGROUND

Autophagy is a cellular self-protection mechanism. The upregulation of adipose-derived stem cells' (ADSCs) autophagy can promote fat graft survival. However, the effect of interfering with adipocyte autophagy on graft survival is still unknown. In addition, autophagy is involved in adipocyte dedifferentiation. We investigated the effect of autophagy on adipocyte dedifferentiation and fat graft survival.

METHODS

The classic autophagy regulatory drugs rapamycin (100 nM) and 3-methyladenine (3-MA; 10 mM) were used to treat adipocytes, adipocyte dedifferentiation was observed, and their effects on ADSCs were detected. In our experiments, 100 nM rapamycin, 10 mM 3-MA and saline were mixed with human adipose tissue and transplanted into nude mice. At 2, 4, 8 and 12 weeks postoperatively, the grafts were harvested for histological and immunohistochemical analysis.

RESULTS

Rapamycin and 3-MA can promote and inhibit adipocyte dedifferentiation by regulating autophagy. Both drugs can inhibit ADSC proliferation, and 10 mM 3-MA can inhibit ADSC adipogenesis. At weeks 8 and 12, the volume retention rate of the rapamycin group (8 weeks, 64.77% ± 6.36%; 12 weeks, 56.13% ± 4.73%) was higher than the control group (8 weeks, 52.62% ± 4.04%; P < 0.05; 12 weeks, 43.17% ± 6.02%; P < 0.05) and the rapamycin group had more viable adipocytes and better vascularization. Compared with the control group, the volume retention rate, viable adipocytes and vascularization of the 3-MA group decreased.

CONCLUSIONS

Rapamycin can promote adipocyte dedifferentiation by upregulating autophagy to promote fat graft survival. 3-MA can inhibit graft survival, but its mechanism includes the inhibition of adipocyte dedifferentiation and ADSC proliferation and adipogenesis.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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 .

Evaluating the Efficacy of Dedifferentiated Fat Cells (DFATs) vs Adipose-Derived Stem Cells (ASCs) in Enhancing the Viability of Fat Grafts

BACKGROUND

Enhancing graft fat survival remains a paramount challenge in autologous fat transplantation surgeries. Dedifferentiated fat cells (DFATs) and adipose-derived stem cells (ASCs) represent 2 pivotal cells with potential to improve fat graft survival rates.

OBJECTIVES

In this study we aimed to compare the effectiveness of DFATs and ASCs in promoting fat graft survival, emphasizing their adipogenic and angiogenic capabilities.

METHODS

Both in vitro and in vivo experiments were conducted. In vitro assessments compared adipogenesis, angiogenesis, osteogenesis, chondrogenesis, cell migration abilities, and surface markers. For in vivo evaluation, a cell-assisted lipotransfer animal model was employed to gauge graft volume retention and histological morphology. Analysis techniques included hematoxylin and eosin staining, Western blotting, and real-time polymerase chain reaction.

RESULTS

In vitro findings suggested a slight superiority of DFATs in adipogenesis and angiogenesis compared to ASCs. In vivo tests demonstrated both cell types surpassed the control in terms of graft volume retention, with the DFATs group marginally outperforming in retention rates and the ASC group presenting a slightly enhanced graft tissue structure.

CONCLUSIONS

Our study underscores the distinct advantages of DFATs and ASCs in bolstering fat graft survival, offering potentially novel insights for plastic surgeons aiming to elevate fat graft survival rates.

The Evolving Function of Vasculature and Pro-angiogenic Therapy in Fat Grafting

Autologous fat grating is a widely-accepted method to correct soft tissue deficiency. Although fat transplantation shows excellent biocompatibility and simple applicability, the relatively low retention rate caused by fat necrosis is still a challenge. The vasculature is integral after fat grafting, serving multiple crucial functions. Rapid and effective angiogenesis within grafts is essential for supplying oxygen necessary for adipocytes' survival. It facilitates the influx of inflammatory cells to remove necrotic adipocytes and aids in the delivery of regenerative cells for adipose tissue regeneration in fat grafts. The vasculature also provides a niche for interaction between adipose progenitor cells and vascular progenitor cells, enhancing angiogenesis and adipogenesis in grafts. Various methods, such as enriching grafts with diverse pro-angiogenic cells or utilizing cell-free approaches, have been employed to enhance angiogenesis. Beige and dedifferentiated adipocytes in grafts could increase vessel density. This review aims to outline the function of vasculature in fat grafting and discuss different cell or cell-free approaches that can enhance angiogenesis following fat grafting.

Increased Fat Graft Survival by Promoting Adipocyte Dedifferentiation

BACKGROUND

Some adipocytes undergo dedifferentiation after fat transplantation, and this may affect the survival of fat grafts. However, this effect has not been adequately studied.

OBJECTIVES

This study aimed to clarify the effect of promoting the dedifferentiation of mature adipocytes on the survival of fat grafts.

METHODS

Mature adipocytes and adipose stem cells (ASCs) were treated with OSI-906 (a specific inhibitor of insulin receptor and insulin-like growth factor-1 receptor) in vitro, and then the dedifferentiation of mature adipocytes and the proliferation of ASCs were evaluated. In the in vivo experiment, human lipoaspirates mixed with phosphate-buffered saline (Group A) or OSI-906 (Group B) were compared in nude mice. Grafts were harvested at 2, 8, and 12 weeks, and volume retention rate, histologic, and immunohistochemical analyses were conducted.

RESULTS

OSI-906 can promote the dedifferentiation of mature adipocytes and inhibit the proliferation of ASCs. At 12 weeks, Group B showed a better volume retention rate (mean [standard deviation, SD], 62.3% [7.61%]) than group A (47.75% [6.11%]) (P < .05). Moreover, viable adipocytes and vascularization showed greater improvement in Group B than in Group A.

CONCLUSIONS

This study suggests that promoting the dedifferentiation of mature adipocytes can improve the survival rate and quality of fat grafts.

Screening for genes, miRNAs and transcription factors of adipogenic differentiation and dedifferentiation of mesenchymal stem cells

BACKGROUND

The purpose of present study was to reveal the molecular mechanisms responsible for both adipogenic differentiation and dedifferentiation of mesenchymal stem cells (MSCs).

METHODS

Microarray data GSE36923 were obtained from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) between adipogenically differentiated cells vs undifferentiated bone marrow-derived MSCs, adipogenically differentiated cells vs dedifferentiated cells samples at day 7 and adipogenically differentiated cells vs dedifferentiated cells samples at day 35 were screened, and overlapped DEGs across the three groups were analyzed. The underlying functions of the upregulated and downregulated DEGs were investigated by Gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis. The protein-protein interaction network was constructed, and hub genes were obtained subsequently. Hub genes were verified with GSE113253 dataset, and then miRNA-gene network and TF-gene network were constructed.

RESULTS

A total of 284 upregulated DEGs and 376 downregulated DEGs overlapped across the three groups. PPAR signaling pathway, AMPK signaling pathway, insulin signaling pathway, carbon metabolism, pyruvate metabolism, fatty acid metabolism, regulation of lipolysis in adipocytes, biosynthesis of amino acids, citrate cycle (TCA cycle) and 2-Oxocarboxylic acid metabolism were the top 10 pathways involving in the upregulated DEGs, and graft-versus-host disease, allograft rejection, viral myocarditis, cell adhesion molecules, phagosome, type I diabetes mellitus, antigen processing and presentation, autoimmune thyroid disease, intestinal immune network for IgA production and rheumatoid arthritis were the top 10 pathways in downregulated DEGs. After validation, the 8 hub genes were IL6, PPARG, CCL2, FASN, CEBPA, ADIPOQ, FABP4 and LIPE. Ten key miRNAs were hsa-mir-27a-3p, hsa-mir-182-5p, hsa-mir-7-5p, hsa-mir-16-5p, hsa-mir-1-3p, hsa-mir-155-5p, hsa-mir-21-3p, hsa-mir-34a-5p, hsa-mir-27a-5p and hsa-mir-30c-5p, and 10 key TFs were TFDP1, GTF2A2, ZNF584, NRF1, ZNF512, NFRKB, CEBPG, KLF16, GLIS2 and MXD4.

CONCLUSION

Our study constructed miRNA-gene network and TF-gene network involved in both adipogenic differentiation and dedifferentiation of MSCs, contributing to enhancing the efficiency of MSCs transplantation in soft tissue defect repair and developing more potent remedies for adipogenesis-related skeletal disorders.

The Application and Efficacy Evaluation of Autologous Fat Transplantation in Antiaging of the Face: Systematic Review and Meta-Analysis

Objective

To evaluate the therapy of autologous fat fine-grain transplantation in the application of antiaging facial by metaelaboration method.

Methods

In Chinese and English databases, such as Wanfang, Weipu, CNKI, PubMed, Cochrane Library, and EMBASE, the literature on the use of autologous fat fines graft in antiaging facial was collected, covering randomized comparative trials, nonrandomized comparative studies, comparative case studies, cohort studies, case reports, and so forth. Meta-analyses were also conducted on complication rates, beauty seeker satisfaction, and one-shot success rates.

Results

This study included 23 studies that held metaelaborations, including a total of 2852 beauty seekers. According to metaelaboration, the complication rate was 0.02 (95% CI: 0.01, 0.04), the satisfaction rate of beauty seekers was 0.95 (95% CI: 0.91, 0.97), and the success rate of one injection is 0.79 (95% CI: 0.73, 0.84).

Conclusion

Autologous fat fine-grain transplantation is obvious and stable in the use of antiaging facial, and it is necessary to popularize the use in clinical practice.