Improving Autologous Fat Grafting in Regenerative Surgery through Stem Cell-Assisted Lipotransfer

Optimal Strategies for Autologous Fat Grafting in Breast Augmentation and Reconstruction: A Systematic Review and Network Meta-Analysis

BACKGROUND

Cell-assisted lipotransfer (CAL) and platelet-rich plasma (PRP)-assisted lipotransfer have been used to overcome the low survival rate of conventional lipotransfer. However, there is still insufficient evidence to determine which technique is the best strategy for autologous fat grafting in breast cosmetic and reconstructive surgery. The present study aimed to compare the efficacy of traditional fat transplantation, CAL, and PRP-assisted lipotransfer.

METHODS

A systematic search was conducted in several databases, including PubMed, Web of Science, Cochrane, ClinicalTrials.gov, and Embase, concluding on January 21, 2024, to identify studies that met the inclusion criteria. Twelve studies were included after a rigorous selection process based on predefined criteria. Statistical analyses were conducted using R version 4.0.5 software with the netmeta and dmetar packages, utilizing a frequentist approach with a random-effects model. A network meta-analysis was performed to compare different fat graft procedures with regard to fat survival rate and complication events.

RESULTS

CAL and PRP-assisted lipotransfer were better than traditional fat grafting in terms of fat survival rate. In addition, there was no significant difference in the incidence of postoperative complications among the CAL, PRP, and traditional groups.

CONCLUSIONS

Given the results of network meta-analysis, it appears that both CAL and PRP-assisted lipotransfer have a higher fat survival rate for autologous fat grafting in breast augmentation and reconstruction. However, the transplantation strategy still needs to be analyzed based on actual conditions in clinical applications.

Cold-Induced Browning: A Novel Method to Improve the Retention Rate of Fat Graft

BACKGROUND

Autologous fat grafting is frequently used to heal soft-tissue defects. The key restriction that must be addressed is the poor transplant retention rate. Growing evidence has demonstrated that the browning of white adipose tissue enhances the survival of fat grafts. We hypothesized that cold-induced browning before transplantation may be a novel method to improve fat graft survival.

METHOD

Mice were kept in the 4 °C environment for 1 week, 2 weeks, and 3 weeks separately to detect whether different times of cold exposure could induce different numbers of beige adipocytes. Then, inguinal fat (roughly 150 mg) was collected and transferred. After post-graft weeks 4 and 12, the grafts were collected. The graft retention rate, histological morphology, vascularization, and browning were all assessed.

RESULTS

Mice inguinal fat showed enhanced beige adipose regeneration as the cold exposure (4 °C) time increased. Cold-induced browning resulted in greater retention, reduced fibrosis and necrosis, and improved angiogenesis at post-graft weeks 4 and 12. Simultaneously, few beige adipocytes were seen in grafts at post-graft weeks 4 and 12.

CONCLUSIONS

Cold-induced browning showed increased retention by promoting angiogenesis in a paracrine manner. Cold exposure of subcutaneous fat before transplantation may be a novel method to improve fat graft retention rate and retention quality.

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 .

Adipose mesenchymal stem cell conditioned medium and extract: A promising therapeutic option for regenerative breast cancer therapy

Introduction

Breast cancer is the second most common cancer and a leading cause of cancer death in U.S. women. The tumor microenvironment, especially nearby adipocytes, plays a crucial role in its progression. Therefore, this study aimed to investigate the effects of human adipose mesenchymal stem cells-derived conditioned medium (SUP) and extract (CE) from on breast cancer cells.

Methods

Human adipose-derived mesenchymal stem cells were isolated and characterized by flow cytometry using Cluster of Differentiation (CD) markers (CD34, CD45, CD90, and CD105). The differentiation potential was confirmed via adipogenic and osteogenic induction. MCF-7 and MDA-MB-231 cells were treated with SUP and CE, and cell viability was assessed using the 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay at 24, 48, and 72 h. Doubling time, colony formation, wound healing, and gene expression for key cancer-related genes (TIMP1, TIMP2, MMP2, PDL1, IDO, Bax, caspase 3, and caspase 9) were also evaluated.

Results

Both SUP and CE significantly inhibited the viability of MCF-7 and MDA-MB-231 cells, reduced their doubling time, and suppressed colony formation. In wound healing assays, cell migration was notably impaired in MDA-MB-231 cells but less so in MCF-7 cells. Real-time polymerase chain reaction revealed downregulation of TIMP1, MMP2, PDL1, and IDO in MDA-MB-231 cells after treatment, while CE increased certain gene expressions in MCF-7 cells. Bax, caspase 3, and caspase 9 expressions were significantly upregulated in MDA-MB-231 cells but not in MCF-7 cells after treatment.

Conclusion

Human adipose-derived mesenchymal stem cells-derived SUP and CE exhibit antitumor effects on breast cancer cells, suggesting a potential therapeutic strategy to suppress tumor progression. Mesenchymal stem cells-SUP and CE could be a safe and novel regenerative approach for breast reconstruction postmastectomy without tumor recurrence risk.

Analysis of Physiological Oxygen Concentrations in Different Abdominal Fat Layers by Body Mass Index

BACKGROUND

Physiological oxygen concentration in adipose tissue is closely linked to metabolic disorders such as chronic inflammation and insulin resistance. However, the nature of the variation in the oxygen levels of adipose tissue with body mass index (BMI) and depths of abdominal fat remain unclear. Therefore, this study aimed to elucidate the patterns of oxygen concentration in adipose tissue layers according to BMI.

METHODS

In this study, patients undergoing abdominal fat removal surgery were divided into the normal-weight (NW) or overweight-obese (OW) groups based on their BMI. Oxygen concentrations in abdominal superficial (sSAT) and deep subcutaneous adipose tissue (dSAT) were measured. The oxygen consumption rate, mean cell area, and capillary density in both tissue layers were compared between the two groups. Furthermore, the interaction between these three variables, BMI, and adipose tissue oxygen concentration, was analyzed using linear regression.

RESULTS

A total of 42 patients were recruited in this study and we observed that oxygen concentration in the sSAT was significantly lower than in the dSAT, irrespective of BMI. In terms of the oxygen concentration in the dSAT, OW's was significantly lower than that of NW's. Linear regression analysis revealed a significant correlation between dSAT oxygen concentration and BMI, mean adipocyte area, and vascular density.

CONCLUSION

Individuals who are obese have significantly lower oxygen levels in the deep abdominal adipose tissue, and this is influenced by BMI, adipocyte area, and capillary density.

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 .

Inhibition of Adipocyte Necroptosis Alleviates Fat Necrosis and Fibrosis After Grafting in a Murine Model

BACKGROUND

Because of the delicate structure of the adipose tissue, fat necrosis accounts for 43.7% of all complications after autologous fat grafting; however, its regulation remains unclear.

OBJECTIVES

The purpose of this study was to examine the role of necroptosis in fat graft remodeling after grafting.

METHODS

Clinical fat graft necrosis samples were collected, and the expression levels of the necroptosis marker phosphorylated(p)-MLKL were analyzed. Transcriptome analysis was performed on fat grafts before and 1 week after transplantation in C57BL/6 mouse fat grafting models. Additionally, the in vivo effects of RIPK1 inhibitor Nec-1s or RIPK3 inhibitor GSK'872 on the fat grafting complications, including fat necrosis and fibrosis, were investigated.

RESULTS

Necroptosis markers were observed and associated with higher occurrence of fibrosis in clinical fat graft necrosis samples compared to normal fat tissue. Amplification and RNA-Seq were conducted on RNA isolated from fat grafts before and after grafting. MLKL, RIPK1, and RIPK3's expression levels were significantly upregulated in comparison to controls. Higher expression levels of necroptotic RNAs were associated with higher levels of DAMPs, including Cxcl2, HMGB1, S100a8, S100a9, Nlrp3, and IL33, and activated proinflammatory signaling pathways, including the TNF, NF-kappa B, and chemokine signaling pathways. Necroptotic inhibitor Nec-1s and GSK'872 robustly suppressed the p-MLKL expression level and significantly inhibited necroptotic cell death, especially in adipocytes. Moreover, administration of Nec-1s and GSK'872 significantly alleviated fat necrosis and subsequent fibrosis in fat grafts.

CONCLUSIONS

Collectively, our study findings highlight the potential therapeutic applications of necroptosis inhibitors in preventing fat necrosis and fibrosis after grafting.

LEVEL OF EVIDENCE: 4

Improving the Retention of Low-Volume Autologous Fat Grafting: A Comparative Analysis of Lipoaspirate Processing Techniques for Facial Feminization

Background

Outcomes following autologous fat grafting have historically been unpredictable because of variability in fat retention rates. The novel poloxamer wash, absorption, mesh filtration system (PWAS) uses proprietary technology to stabilize and concentrate lipoaspirate. Its use in low-volume fat grafting has not been reported.

Objectives

The authors in this study aimed to compare PWAS technology with traditional lipoaspirate processing techniques in low-volume fat grafting procedures.

Methods

Medical charts were reviewed to determine a consecutive cohort of patients who underwent fat grafting for facial feminization. All patients had obtained preoperative and postoperative 3-dimensional facial imaging. Patients were grouped based on the method of lipoaspirate processing. The analysis software was used to measure changes in facial volume, and percent retention was calculated.

Results

Between September 2021 and February 2023, 11 facial fat grafting procedures were performed using the PWAS, and 5 performed using traditional lipoaspirate osmotic filtration with Telfa. Age and BMI were statistically similar between both the groups (P > .1). The average volume of lipoaspirate that was grafted was 23.4 mL (standard deviation [SD] 10.9 mL) and similar between both the groups (P > .1). The mean follow-up duration was 7.1 months (SD 3.1 months): 7.2 months, SD 3.5 months in the PWAS group vs 7.0 months, SD 2.2 months in the osmotic filtration group (P > .5). The average fat volume retention rate was 73.1% (SD 6.8%) in patients in whom the PWAS was used when compared with 46.1% (SD 5.2%) in patients in whom osmotic filtration was used (P > .01).

Conclusions

For patients undergoing low volume fat grafting, the PWAS technology may result in improved fat retention rates when compared with traditional lipoaspirate processing with Telfa.

Level of Evidence 4

Adipose-Derived Stem Cells: Angiogenetic Potential and Utility in Tissue Engineering

Adipose tissue (AT) is a large and important energy storage organ as well as an endocrine organ with a critical role in many processes. Additionally, AT is an enormous and easily accessible source of multipotent cell types used in our day for all types of tissue regeneration. The ability of adipose-derived stem cells (ADSCs) to differentiate into other types of cells, such as endothelial cells (ECs), vascular smooth muscle cells, or cardiomyocytes, is used in tissue engineering in order to promote/stimulate the process of angiogenesis. Being a key for future successful clinical applications, functional vascular networks in engineered tissue are targeted by numerous in vivo and ex vivo studies. The article reviews the angiogenic potential of ADSCs and explores their capacity in the field of tissue engineering (TE).

Delivery of microRNA-423-5p by exosome from adipose-derived stem/stromal cells inhibits DVL3 to potentiate autologous fat graft survival through adipogenesis and inflammatory response

Autologous fat grafting represents a reconstructive technique but is limited by unstable graft retention. Based on existing reports and bioinformatics prediction, we hypothesized that delivering exosomes from human adipose-derived stem/stromal cells (hADSC-Exo) would increase fat graft survival and further explore the mechanism. hADSC-Exo were extracted and identified. An autologous fat grafting model was established using donor and recipient mice, followed by hADSC-Exo treatment. hADSC-Exo promoted the retention of autologous fat grafts in mice, along with increased adipocyte activity, angiogenesis, and decreased inflammation in grafts. Moreover, hADSC-Exo potentiated the adipose differentiation of 3T3-L1 cells, enhanced the angiogenic and migratory capacity of human umbilical vein endothelial cells, and inhibited the inflammation and viability of RAW 264.7 cells. The therapeutic effect of hADSC-Exo on fat grafting was associated with the delivery of microRNA (miR)-423-5p. Deletion of miR-423-5p in Exo impaired the function of hADSC-Exo on fat retention. miR-423-5p bound to DVL3 to suppress DVL3 expression, and DVL3 deletion promoted adipose differentiation of 3T3-L1 cells. In conclusion, our findings further widen the theoretical basis of the clinical application of hADSC-Exo in autologous fat grafts.