The Future of Fat Grafting

The effect of exogenous mitochondria in enhancing the survival and volume retention of transplanted fat tissue in a nude mice model

BACKGROUND

Despite the pivotal role of fat grafting in plastic, reconstructive, and aesthetic surgery, inconsistent survival rates of transplanted adipose tissue, primarily due to early ischemic and hypoxic insults, remain a significant challenge. The infusion of healthy mitochondria has emerged as a promising intervention to support tissue recovery from ischemic, hypoxic, and other types of damages across various organ systems.

OBJECTIVES

This study aims to evaluate the impact of supplementing human adipose tissue grafts with healthy exogenous mitochondria on their volume and mass retention rates when transplanted into the subcutaneous layers of nude mice. This approach seeks to improve and optimize fat grafting techniques.

METHODS

Human adipose tissues were preconditioned with exogenous mitochondria (10 µg/mL), a combination of exogenous mitochondria and the inhibitor Dyngo-4a, Dyngo-4a alone, or PBS, and then transplanted into the subcutaneous tissue of 24 nude mice. Samples were harvested at 1 and 3 months post-transplantation for analysis of mass and volume retention. The structural morphology and integrity of the adipose tissues were assessed using Hematoxylin and Eosin (H&E) staining.

RESULTS

Mitochondrial preconditioning significantly enhanced the retention of mass and volume in fat grafts, demonstrating superior structural morphology and integrity compared to the control group.

CONCLUSIONS

This study highlights the potential of exogenous mitochondrial augmentation in fat transplantation to significantly improve fat graft survival, thereby optimizing the success of fat grafting procedures.

Differential Secretomes of Processed Adipose Grafts, the Stromal Vascular Fraction, and Adipose-Derived Stem Cells

There are multiple methods to prepare lipoaspirate for autologous fat transfer; however, graft retention remains unpredictable. The purpose of this study was to compare the cellular and protein composition of adipose grafts and the stromal vascular fraction (SVF) resulting from three common techniques to prepare adipose grafts. Adipose grafts were harvested from healthy donors and processed via three techniques: centrifugation (C), a single-filter (SF) device, and a double-filtration (DF) system. Part of each graft was analyzed or further processed to isolate the SVF. Cell viability, surface markers, cytokine, and growth factors were compared between the graft and SVF as well as adipose-derived stem cells (ASCs). Overall, we found variations across the three processing techniques and among the graft components (ASCs, SVF, and fat). Cell viability within the grafts was similar (94.6%, 92.3%, and 93.6%; P = 0.93). The trend was a greater percentage of ASCs from SF versus DF or centrifugation (6.95%, 4.63%, and 1.93%, respectively, P = 0.06). Adipogenic markers (adiponectin and leptin) were similar among all three grafts (P = 0.45). Markers of tissue remodeling were greatest in the SVF compared with fat and ASCs, regardless of processing technique. There was higher relative expression of MMP-9 (2×), Extracellular matrix metalloproteinase inducer (EMMPRIN) (2.5×), endoglin (5×), and IL-8 (1.5×) in the SVF (P < 0.005). Our study identified differences in cytokine expression in adipose grafts and the SVF, particularly in cytokines important in inflammation and wound healing. These secretomes may impact graft retention and fat necrosis and have the potential implications in cell-assisted lipotransfer. There were no significant differences between the final products of any of the processing techniques.

Autologous Fat Grafting-A Panacea for Scar Tissue Therapy?

Scars may represent more than a cosmetic concern for patients; they may impose functional limitations and are frequently associated with the sensation of itching or pain, thus impacting both psychological and physical well-being. From an aesthetic perspective, scars display variances in color, thickness, texture, contour, and their homogeneity, while the functional aspect encompasses considerations of functionality, pliability, and sensory perception. Scars located in critical anatomic areas have the potential to induce profound impairments, including contracture-related mobility restrictions, thereby significantly impacting daily functioning and the quality of life. Conventional approaches to scar management may suffice to a certain extent, yet there are cases where tailored interventions are warranted. Autologous fat grafting emerges as a promising therapeutic avenue in such instances. Fundamental mechanisms underlying scar formation include chronic inflammation, fibrogenesis and dysregulated wound healing, among other contributing factors. These mechanisms can potentially be alleviated through the application of adipose-derived stem cells, which represent the principal cellular component utilized in the process of lipofilling. Adipose-derived stem cells possess the capacity to secrete proangiogenic factors such as fibroblast growth factor, vascular endothelial growth factor and hepatocyte growth factor, as well as neurotrophic factors, such as brain-derived neurotrophic factors. Moreover, they exhibit multipotency, remodel the extracellular matrix, act in a paracrine manner, and exert immunomodulatory effects through cytokine secretion. These molecular processes contribute to neoangiogenesis, the alleviation of chronic inflammation, and the promotion of a conducive milieu for wound healing. Beyond the obvious benefit in restoring volume, the adipose-derived stem cells and their regenerative capacities facilitate a reduction in pain, pruritus, and fibrosis. This review elucidates the regenerative potential of autologous fat grafting and its beneficial and promising effects on both functional and aesthetic outcomes when applied to scar tissue.

Role of Autologous Fat Transplantation Combined with Negative-Pressure Wound Therapy in Treating Rat Diabetic Wounds

BACKGROUND

Negative-pressure wound therapy (NPWT) and autologous fat transplantation (AFT) are two clinical modalities for plastic and reconstructive surgery. At present, there are few reports on the combination of these two methods in treating diabetic wounds. This study aimed to explore the effect of this combined therapy on diabetic wound healing.

METHODS

Full-thickness dorsal cutaneous wounds in rats with streptozotocin-induced diabetes were treated with either NPWT, AFT, or combined therapy. Rats covered with commercial dressings served as the control group. Macroscopic healing kinetics were examined. The levels of inflammation-related factors, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), monocyte chemoattractant protein-1, arginase-1, and inducible nitric oxide synthase (iNOS) and angiogenesis-related factors such as vascular endothelial growth factor, were measured in the wound tissues on days 3, 7, and 14; immunohistochemical staining for arginase-1, iNOS, and CD31 was performed on days 3, 7, and 14. The length of reepithelialization was investigated on day 14.

RESULTS

The combined therapy promoted faster wound healing than the other treatments. The expression levels of the proinflammatory factors IL-1β, IL-6, monocyte chemoattractant protein-1 (MCP-1), and iNOS were reduced, and arginase-1 expression was increased compared with those in the other groups. The expression levels of vascular endothelial growth factor and CD31 in the NPWT-combined-with-AFT group were significantly higher than those in the other groups. Reepithelialization was faster in the NPWT-combined-with-AFT group (by day 14) than in the other groups.

CONCLUSION

Combining NPWT and AFT can enhance diabetic wound healing by improving wound inflammation and increasing wound vascularization.

CLINICAL RELEVANCE STATEMENT

The authors designed a randomized controlled trial of diabetic rats to confirm that NPWT can enhance the vascularization and improve inflammation of the diabetic wound after the autologous fat transplantation treatment. This article may provide a new idea for treating diabetic wounds.

Deconstructing Fat to Reverse Radiation Induced Soft Tissue Fibrosis

Adipose tissue is composed of a collection of cells with valuable structural and regenerative function. Taken as an autologous graft, these cells can be used to address soft tissue defects and irregularities, while also providing a reparative effect on the surrounding tissues. Adipose-derived stem or stromal cells are primarily responsible for this regenerative effect through direct differentiation into native cells and via secretion of numerous growth factors and cytokines that stimulate angiogenesis and disrupt pro-inflammatory pathways. Separating adipose tissue into its component parts, i.e., cells, scaffolds and proteins, has provided new regenerative therapies for skin and soft tissue pathology, including that resulting from radiation. Recent studies in both animal models and clinical trials have demonstrated the ability of autologous fat grafting to reverse radiation induced skin fibrosis. An improved understanding of the complex pathologic mechanism of RIF has allowed researchers to harness the specific function of the ASCs to engineer enriched fat graft constructs to improve the therapeutic effect of AFG.

Effects of Melatonin on Fat Graft Retention Through Browning of Adipose Tissue and Alternative Macrophage Polarization

BACKGROUND

Melatonin is a widely used drug that can affect adipocyte inflammation, resulting in adipose tissue browning. Inducing the browning of white fat and changing the inflammatory microenvironment of early transplanted fat have positive effects on the retention rate of fat grafts. This study aimed to evaluate the effects of melatonin on fat graft retention, determine whether it is related to adipose tissue browning and the inflammatory microenvironment, and explore the underlying mechanisms.

METHODS

A C57BL/6 mice fat transplantation model was established. The mice were divided into a control group (ethanol), a high-dose group (40 mg/kg/day melatonin), a medium-dose group (20 mg/kg/day melatonin), and a low-dose group (10 mg/kg/day melatonin). They were also given oral gavage treatment for 2 weeks. The grafted fat was collected 2, 4, and 12 weeks after treatment.

RESULTS

The medium-dose and high-dose melatonin groups had significantly higher fat graft retention rates than the control group at 12 weeks. The medium-dose melatonin group had smaller multilocular adipocytes, which enhanced the expression of uncoupling protein 1 and increased neovascularization in the grafted fat. The medium-dose group also had a higher distribution of M2 macrophages.

CONCLUSIONS

These findings suggest that melatonin administration can improve the retention of fat grafts through polarization of macrophages toward the anti-inflammatory type and induction of adipose tissue browning.

NO LEVEL ASSIGNED

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A Preliminary Exploratory Study of Autologous Fat Transplantation in Breast Augmentation With Different Fat Transplantation Planes

Background

Autologous fat transfer is common in breast augmentationor reconstruction. However, AFG recipient site in the breast for fat grafting has not been carefully investigated.

Methods

Forty female patients requiring breast augmentation with fat grafting were randomly assigned into two groups. The retromammary group received 2/3 fat into the retromammary space and the other 1/3 into the subcutaneous and retropectoral planes. The retropectoral group received 2/3 fat into the retropectoral plane and the other 1/3 into the subcutaneous and retromammary planes. The fat grafting result at 6 months was assessed by 3D laser surface scanning and then ultrasound. Any complications were recorded during follow-up. Samples from a patient who underwent fat grafting for 6 months was obtained and histological examination was conducted.

Results

No significant difference in the retention rate after 6 months was observed between the two groups (retromammary group: 35.9% ± 6.6; retropectoral group: 39.3% ± 5.1, p = 0.1076). The retromammary grouphad a higher incidence of oil cyst formation than the retropectoral group. Histological examination showed that there were more oil cysts and mac2 positive macrophage infiltration in the fat cells in retromammary group, while retropectoral group had more small-size adipocytes.

Conclusion

Although fat grafting into the retropectoral plane did not provide a superior fat graft retention rate, it did lower the incidence of complications. The retropectoral space show great potential to become a favorable recipient site.