Function-preserving fat grafting in the breast: Results based on 18 years of experience

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.

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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.

[Cytosteatonecrosis after breast reconstruction by fat flap with or without ischemic preconditioning]

INTRODUCTION

Cytosteatonecrosis (CTN) is a frequent postoperative complication after breast autologous reconstruction using DIEP (deep inferior epigastric perforator) flap. CTN radiological diagnostic reveals different types of lesions, as nodes or extended fat necrosis, which become in some cases infected, or pass for tumor recurrence after breast cancer treatment. CTN is caused by intraoperative ischemia of the flap, and no current method can prevent postoperative CTN development after DIEP breast reconstruction. Mechanical ischemic preconditioning, consisting in intraoperative briefs consecutive cycles of ischemia reperfusion using vascular clamp upon the graft pedicle, is used in transplantation surgery. This procedure improves the graft tolerance towards ischemic surgical lesions. The aim of this retrospective observational study was to assess PCIM effects on CTN development after DIEP surgery, comparing CTN occurrence after breast reconstruction using DIEP flap with or without intraoperative PCIM.

MATERIAL AND METHODS

All patients breats reconstructed using DIEP flap between novembre 2020 and may 2022, presenting 6 months postoperative breast echography were retrospectively included. Primary outcome was the ultrasonic existence of CTN, according to the Wagner classification. Clinical data, postoperative outcomes such as infection, hematoma or surgical revision, and length of stay in hospital were also recorded.

RESULTS

Twenty nine patients among which 8 PCIM were included. CTN occurrence rate after PCIM (25%) was quite lower than CTN rate without PCIM (71,4%), although the difference was not significant (P=0,088). Other postoperative complications rates were not significantly different with or without PCIM.

CONCLUSION

PCIM seems to improve CTN occurrence after DIEP breast reconstruction, improving fat flap tolerance to ischemic perioperative lesions. Those preliminary results need to be confirmed with clinical prospective study.

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.