Morphological features of cell death and tissue remolding of fat grafts

Histological Properties of Adipose Tissue as an Autologous Tissue Filler Harvested from Different Donor Areas and Impact of Centrifugation

Background

As a burgeoning technique in reconstructive and aesthetic surgery, lipofilling's success is hindered by the unpredictability of graft integrity and quality. This study addresses the critical need to enhance consistency and reproducibility by exploring the clinical utility of adipose tissue from specific body areas, considering the influence of patient-specific factors and mechanical processing on fat graft integrity and morphology.

Methods

In a prospective, randomized, single-blind study, 52 patients undergoing surgical reconstruction due to significant deformities were enrolled. Lipoaspiration from four areas was performed. Adipose tissue was compared using five parameters of tissue damage and 10 parameters of graft integrity, assessed immediately postcollection and after centrifugation. The study aimed to evaluate the structural integrity and clinical applicability of adipocytes.

Results

Morphological assessment revealed no significant differences in adipose tissue quality across donor sites, suggesting consistent graft quality regardless of the harvesting location. Centrifugation induced more morphological damage than noncentrifuged samples, but the overall graft integrity was maintained due to increased cell density. Higher graft acceptance parameters were noted in noncentrifuged samples compared with centrifuged ones.

Conclusions

Despite centrifugation-induced morphological changes, adipose tissue integrity remains relatively unaffected, supporting a flexible approach to donor site selection. The consistent quality of adipose tissue underscores the potential for autologous fat transplantation across various clinical scenarios. Optimizing graft processing techniques is crucial for enhancing the predictability and efficacy of lipofilling.

Glutathione supplementation improves fat graft survival by inhibiting ferroptosis via the SLC7A11/GPX4 axis

BACKGROUND

Autologous fat grafting is hampered by unpredictable graft survival, which is potentially regulated by ferroptosis. Glutathione (GSH), a powerful antioxidant used in tissue preservation, has ferroptosis-regulating activity; however, its effects on fat grafts are unclear. This study investigated the effects and mechanisms of GSH in fat graft survival.

METHODS

Human lipoaspirates were transplanted subcutaneously into the backs of normal saline-treated (control) or GSH-treated nude mice. Graft survival was evaluated by magnetic resonance imaging and histology. RNA sequencing was performed to identify differentially expressed genes and enriched pathways. GSH activity was evaluated in vitro using an oxygen and glucose deprivation (OGD) model of adipose-derived stem cells.

RESULTS

Compared with control group, GSH induced better outcomes, including superior graft retention, appearance, and histological structures. RNA sequencing suggested enhanced negative regulation of ferroptosis in the GSH-treated grafts, which showed reduced lipid peroxides, better mitochondrial ultrastructure, and SLC7A11/GPX4 axis activation. In vitro, OGD-induced ferroptosis was ameliorated by GSH, which restored cell proliferation, reduced oxidative stress, and upregulated ferroptosis defense factors.

CONCLUSIONS

Our study confirms that ferroptosis participates in regulating fat graft survival and that GSH exerts a protective effect by inhibiting ferroptosis. GSH-assisted lipotransfer is a promising therapeutic strategy for future clinical application.

Research progress of mechanisms of fat necrosis after autologous fat grafting: A review

Currently, autologous fat grafting is the common surgery employed in the department of plastic and cosmetic surgery. Complications after fat grafting (such as fat necrosis, calcification, and fat embolism) are the difficulties and hotspots of the current research. Fat necrosis is one of the most common complications after fat grafting, which directly affects the survival rate and surgical effect. In recent years, researchers in various countries have achieved great results on the mechanism of fat necrosis through further clinical and basic studies. We summarize recent research progress on fat necrosis in order to provide theoretical basis for diminishing it.

Clinical Study Demonstrates that Electromagnetic Muscle Stimulation Does Not Cause Injury to Fat Cells

Background and Objectives

A previous pre‐clinical study on electromagnetic muscle stimulation (EMMS) suggested that fat cell apoptosis occurs following treatment in a porcine model. While EMMS can induce changes in muscle, the effect on fat tissue is not established. This clinical study sought to assess adipose tissue response to EMMS in comparison to cryolipolysis treatment.

Study Design/Materials and Methods

Study subjects were recruited prior to abdominoplasty to receive body contouring treatments and subsequently to obtain tissue for histological analysis. Non‐invasive abdominal treatments were delivered using a commercially available (n = 6) or prototype (n = 3) EMMS system or a cryolipolysis system (n = 2). Subjects received a single EMMS treatment (100% intensity for 30 minutes) or a single cryolipolysis treatment (−11°C for 35 minutes) to the abdomen. Superficial and deep (i.e., adjacent to muscle layer) subcutaneous adipose tissue was harvested at set timepoints post‐treatment. The presence or absence of an inflammatory response was evaluated using standard hematoxylin and eosin (H&E) staining. As adipocytes that are destined to become apoptotic cannot be distinguished by traditional H&E staining during the early phases of injury, irreversible fat cell injury was assessed using perilipin immunofluorescence.

Results

Following H&E histological analysis at 3, 10, 11, and 17 days post‐treatment, no EMMS‐treated samples showed an inflammatory response in either the superficial or deep subcutaneous adipose tissue. For the cryolipolysis‐treated adipose tissue, however, the H&E staining revealed a marked inflammatory response with an influx of neutrophils, lymphocytes, and macrophages at timepoints consistent with previous histological studies. Further, loss of perilipin staining provided clear visual evidence of irreversible fat cell injury in the cryolipolysis‐treated adipose tissue. In contrast, the electromagnetic muscle stimulation‐treated samples showed persistence of perilipin staining of adipose tissue indicating that all fat cells were viable.

Conclusion

This study failed to demonstrate either fat cell injury or inflammatory response following EMMS treatment. While electromagnetic muscle stimulation may non‐invasively induce muscle changes, this clinical study found no evidence of an impact injurious or otherwise on subcutaneous fat. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC

Molecular Mechanisms of Adipose Tissue Survival during Severe Hypoxia: Implications for Autologous Fat Graft Performance

Background:

Variable retention outcomes remain a significant issue in autologous fat grafting procedures. Among seemingly similar patients, using identical harvesting procedures, variability in graft retention is noted. Recent data suggest that the inherent characteristics of donor adipose tissue dictate graft healing outcomes. The goal of this study was to elucidate intrinsic qualities of human adipose tissue that confer resistance to ischemic stress to therapeutically target such mechanisms and improve overall results of fat grafts.

Methods:

Whole fat from 5 female patients was cultured in vitro under severe (1% O₂) and mild (8% O₂) hypoxic conditions. Microarray analysis of 44 hypoxia-related genes was performed. Perilipin was used to visualize viable adipocytes. Macrophage phenotypes were identified using PCR.

Results:

Analysis of adipocyte survival with perilipin suggested improved viability for tissue obtained from high BMI donors. Microarray data revealed a significant positive correlation for induced expression of ANGPTL4, a survival gene, and subject BMI (P = 0.0313) during hypoxic conditions whereas HIF1α and HIF2α genes were negatively correlated with donor BMI (P = 0.0003 and 0.0303). Interestingly, induced differentiation of proinflammatory M1 macrophages was negatively correlated with BMI under hypoxia (P = 0.0177).

Conclusions:

The innate resilience of adipocytes to hypoxia and relative macrophage activation play a crucial role in fat graft retention. This study suggests that adipose tissue from high BMI donors demonstrates greater resistance to hypoxia-induced apoptosis associated with an increased expression of ANGPTL4. Therefore, therapeutic interventions that target this factor may improve clinical adipose graft survival.

Application of Epineural Sheath as a Novel Approach for Fat Volume Maintenance

INTRODUCTION

Various methods have been suggested to improve fat graft survival and decrease graft loss. The exact mechanism of fat graft survival is still unclear, and new strategies are needed to further investigate it.

MATERIALS AND METHODS

The efficacy of epineural sheath in fat volume maintenance was tested in rat model. Five experimental groups were created: group 1, fat graft without any coverage; group 2, epineural sheath tube alone; group 3, epineural sheath tube filled with fat graft; group 4, fat graft mixed with minced epineural sheath without any coverage; and group 5, fat graft covered with the epineural sheath patch. All grafts were implanted into the dorsal subcutaneous region and were followed for up to 12 weeks, when samples were harvested for hematoxylin and eosin and immunostaining for vascular endothelial growth factor expression and perilipin evaluation of fat viability.

RESULTS

In groups 1 and 4, over 25% of graft loss was observed at first week, over 50% at third week, and 100% at sixth week postimplantation. The weight of fat graft within the epineural sheath tube and the weight of epineural tube (ET) alone were maintained up to 12 weeks postimplantation. The weight of fat graft within the epineural patch was maintained up to 6 weeks, but 50% of weight loss was observed between 6 and 12 weeks. Structure of the epineural sheath tubes and patches was intact, and no leakage of fat graft was observed. Based on hematoxylin and eosin staining, normal structure and integrity of the fat graft within the ET were preserved up to 12 weeks postimplantation. Characteristic adipocyte morphology was confirmed by perilipin staining, showing viable fat cells in groups 3 and 5 at 12 weeks. Increased vascular endothelial growth factor expression was observed in groups 2, 3, 4, and 5.

CONCLUSIONS

Both, the ETs and epineural patches maintained 100% and 50% of fat graft weight at 12 weeks postimplantation, respectively. These results were confirmed by histology and immunostaining showing viable adipocytes within the epineural patches (6 weeks) and tubes (12 weeks). These results are encouraging and justify further evaluation of fat volume maintenance in preclinical large animal model in preparation to clinical application.

Plasticity of adipose tissue in response to fasting and refeeding in male mice

Background

Fasting is the most widely prescribed and self-imposed strategy for treating excessive weight gain and obesity, and has been shown to exert a number of beneficial effects. The aim of the present study was to determine the exact role of fasting and subsequent refeeding on fat distribution in mice.

Methods

C57/BL6 mice fasted for 24 to 72 h and were then subjected to refeeding for 72 h. At 24, 48 and 72 h of fasting, and 12, 24, 48 and 72 h of refeeding, the mice were sacrificed, and serum and various adipose tissues were collected. Serum biochemical parameters, adipose tissue masses and histomorphological analysis of different depots were detected. MRNA was isolated from various adipose tissues, and the expressions of thermogenesis, visceral signature and lipid metabolism-related genes were examined. The phenotypes of adipose tissues between juvenile and adult mice subjected to fasting and refeeding were also compared.

Results

Fasting preferentially consumed mesenteric fat mass and decreased the cell size of mesenteric depots; however, refeeding recovered the mass and morphology of inguinal adipose tissues preferentially compared with visceral depots. Thermogenesis-related gene expression in the inguinal WAT and interscapular BAT were suppressed. Mitochondrial biogenesis was affected by fasting in a depot-specific manner. Furthermore, a short period of fasting led to an increase in visceral signature genes (Wt1, Tcf21) in subcutaneous adipose tissue, while the expression of these genes decreased sharply as the fasting time increased. Additionally, lipogenesis-related markers were enhanced to a greater extent greater in subcutaneous depots compared with those in visceral adipose tissues by refeeding. Although similar phenotypic changes in adipose tissue were observed between juvenile mice and adult mice subjected to fasting and refeeding, the alterations appeared earlier and more sensitively in juvenile mice.

Conclusions

Fasting preferentially consumes lipids in visceral adipose tissues, whereas refeeding recovers lipids predominantly in subcutaneous adipose tissues, which indicated the significance of plasticity of adipose organs for fat distribution when subject to food deprivation or refeeding.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-016-0159-x) contains supplementary material, which is available to authorized users.