Fat Grafting for Thermal Injury: Current State and Future Directions

Fat Grafting: Basic Science, Techniques, and Patient Management

In this review, a summary of the rich history of autologous fat grafting is provided, and a comprehensive summary of the science and theory behind autologous adipocyte transplantation, as well as the techniques commonly used is described. These include recipient site preparation, harvesting, processing, and engraftment. In addition, important considerations for preoperative and postoperative management are discussed to maximize graft retention. Special considerations in grafting to the breast, face, and buttocks are also summarized.

Burn scar regeneration with the "SUFA" (Subcision and Fat Grafting) technique. A prospective clinical study

Background

Treatment of burn scars with traditional surgical techniques is challenging due to recurrent contractures. Fat grafting has been previously used in small clinical series and results are often biased by lack of scientific validating methods. Fat grafting in clinical practice is often evaluated for its filler properties and rarely scientifically validated for its potential in dermal regeneration. Animal studies have shown dermal regeneration with new deposition and reorientation of the collagen fiber. Our study aims to apply the validity of in vitro studies to clinical practice.

Methods

Our study prospectively evaluated outcomes in 12 patients treated with the “SUFA” technique (Subcision and Fat Grafting) for debilitating contracted burns scars limiting range of motion. Results were evaluated clinically with the Vancouver scale and by range of motion at 1, 3, 6 and 12 months. Dermal regeneration was evaluated by looking at dermis thickening using high definition ultrasound and scar remodeling looking at reorientation and new deposition of collagen fibers with hematoxylin-eosin histology and monoclonal antibodies against collagen type 1 and 3.

Results

Statistically significant clinical improvements in range of motion of the affected joints was observed (P<0.05). Fat reabsorption occurred with a mean of 40%. Thickening of dermis and redistribution and reorientation of the collagen fibers within the dermis was also demonstrated.

Conclusions

Our results present the first clinical scientific evidence of dermal regeneration in fat grafting. Using monoclonal antibodies and high definition ultrasounds, we demonstrate the first evidence of dermis regeneration in a clinical scenario.

Autologous breast reconstruction using the immediately lipofilled extended latissimus dorsi flap

BACKGROUND

The latissimus dorsi flap is a popular choice for autologous breast reconstruction. To dramatically improve volume, we report our experience of using the immediately lipofilled extended latissimus dorsi (ELD) flap and show it as a valid option for autologous breast reconstruction.

METHODS

Patients undergoing the procedure between December 2013 and June 2016 were included. Demographic, clinical and operative factors were analysed, together with in-hospital morbidity and duration of postoperative hospital stay.

RESULTS

A total of 71 ELD flaps with immediate lipofilling were performed. Forty-five reconstructions were immediate and the remaining 26 delayed. Median (range) volume of autologous fat injected immediately was 171 ml (40-630 ml). Contralateral reductions were performed in 25 patients with the median reduction volume 185 g (89-683 g). Median duration of admission was 6.5 (3-18) days and patients were followed up for 12 months (1-37). Three total flap failures occurred and had to be excised (4%). One haematoma occurred requiring drainage (1%). Signs of infection requiring intravenous antibiotics occurred in five patients (7%). In 5 patients wound dehiscence occurred, and only two of these required resuturing (3%). In total, 7 patients developed a seroma requiring repeated drainage (10%). Three reconstructions experienced mild mastectomy flap necrosis with no needing reoperation (4%).

CONCLUSIONS

Our experience represents the largest series to date and shows that in carefully selected patients the technique is safe, can avoid the requirement for implants, and has the potential to streamline the reconstructive journey.

Fat Grafting for Burn, Traumatic, and Surgical Scars

Fat grafting provides a reliable modality with expanding usefulness in reconstructive plastic surgery. Owing to its mechanical and theorized regenerative properties, adipose tissue can improve scar qualities and scar related symptoms when grafted adjacent to or within a scar. In this article, the literature describing the effect of fat grafting on various types of scars, current scientific understanding of fat grafting for scars, and our current approach to the management of problematic burn scars are reviewed.

Peripheral Neuropathy and Nerve Compression Syndromes in Burns

Peripheral neuropathy and nerve compression syndromes lead to substantial morbidity following burn injury. Patients present with pain, paresthesias, or weakness along a specific nerve distribution or experience generalized peripheral neuropathy. The symptoms manifest at various times from within one week of hospitalization to many months after wound closure. Peripheral neuropathy may be caused by vascular occlusion of vasa nervorum, inflammation, neurotoxin production leading to apoptosis, and direct destruction of nerves from the burn injury. This article discusses the natural history, diagnosis, current treatments, and future directions for potential interventions for peripheral neuropathy and nerve compression syndromes related to burn injury.

Modern trends in lipomodeling

Lipomodeling is the process of relocating autologous fat to change the shape, volume, consistency, and profile of tissues, with the aim of reconstructing, rejuvenating, and regenerating body features. There have been several important advancements in lipomodeling procedures during the last thirty years. Four clinical steps are important for the success of engraftment: fat harvesting, fat processing, fat reinjection, and preconditioning of the recipient site. With the discovery of adipose derived stem cells and dedifferentiated cells, fat cells become a major tool of regenerative medicine. This article reviews recent trends in lipomodeling trying to understand most of the issues in this field.

The Current State of Fat Grafting: A Review of Harvesting, Processing, and Injection Techniques

BACKGROUND

Interest in and acceptance of autologous fat grafting for use in contour abnormalities, breast reconstruction, and cosmetic procedures have increased. However, there are many procedural variations that alter the effectiveness of the procedure and may account for the unpredictable resorption rates observed.

METHODS

The authors highlighted studies investigating the effects of harvesting procedures, processing techniques, and reinjection methods on the survival of fat grafts. This review focused on the impact different techniques have on outcomes observed in the following: in vitro analyses, in vivo animal experiments, and human studies.

RESULTS

This systemic review revealed the current state of the literature. There was no significant difference in the outcomes of grafted fat obtained from different donor sites, different donor-site preparations, harvest technique, fat harvesting cannula size, or centrifugation speed, when tumescent solution was used. Gauze rolling was found to enhance the volume of grafted fat, and no significant difference in retention was observed following centrifugation, filtration, or sedimentation in animal experiments. In contrast, clinical studies in patients found more favorable outcomes with fat processed by centrifugation compared with sedimentation. In addition, higher retention was observed with slower reinjection speed and when introduced into less mobile areas.

CONCLUSIONS

There has been a substantial increase in research interest to identify methodologies for optimizing fat graft survival. Despite some differences in harvest and implantation technique in the laboratory, these findings have not translated into a universal protocol for fat grafting. Therefore, additional human studies are necessary to aid in the development of a universal protocol for clinical practice.

Wound healing after thermal injury is improved by fat and adipose-derived stem cell isografts

Patients with severe burns suffer functional, structural, and esthetic complications. It is important to explore reconstructive options given that no ideal treatment exists. Transfer of adipose and adipose-derived stem cells (ASCs) has been shown to improve healing in various models. The authors hypothesize that use of fat isografts and/or ASCs will improve healing in a mouse model of burn injury. Twenty 6 to 8 week old C57BL/6 male mice received a 30% surface area partial-thickness scald burn. Adipose tissue and ASCs from inguinal fat pads were harvested from a second group of C57BL/6 mice. Burned mice received 500 μl subcutaneous injection at burn site of 1) processed adipose, 2) ASCs, 3) mixed adipose (adipose and ASCs), or 4) sham (saline) injection (n = 5/group) on the first day postinjury. Mice were followed by serial photography until being killed at days 5 and 14. Wounds were assessed for burn depth and healing by hematoxylin and eosin (H&E) and immunohistochemistry. All treated groups showed improved healing over controls defined by decreased wound depth, area, and apoptotic activity. After 5 days, mice receiving ASCs or mixed adipose displayed a non-significant improvement in vascularization. No significant changes in proliferation were noted at 5 days. Adipose isografts improve some early markers of healing postburn injury. The authors demonstrate that addition of these grafts improves specific structural markers of healing. This improvement may be because of an increase in early wound vascularity postgraft. Further studies are needed to optimize use of fat or ASC grafts in acute and reconstructive surgery.

Studies in fat grafting: Part III. Fat grafting irradiated tissue--improved skin quality and decreased fat graft retention

BACKGROUND

Following radiation therapy, skin becomes fibrotic and can present a difficult problem for reconstructive surgeons. There is an increasing belief that fat grafting under irradiated skin can reverse the damage caused by radiation. The present study evaluated the effect of fat grafting on irradiated skin, along with fat graft quality and retention rates in irradiated tissue.

METHODS

Nine adult Crl:NU-Foxn1 CD-1 mice underwent 30-Gy external beam irradiation of the scalp. Four weeks after irradiation, scalp skin from irradiated and nonirradiated mice was harvested and compared histologically for dermal thickness, collagen content, and vascular density. Human fat grafts were then injected in the subcutaneous plane of the scalp. Skin assessment was performed in the irradiated group at 2 and 8 weeks after grafting, and fat graft retention was measured at baseline and every 2 weeks up to 8 weeks after grafting using micro-computed tomography. Finally, fat graft samples were explanted at 8 weeks, and quality scoring was performed.

RESULTS

Fat grafting resulted in decreased dermal thickness, decreased collagen content, and increased vascular density in irradiated skin. Computed tomographic analysis revealed significantly decreased fat graft survival in the irradiated group compared with the nonirradiated group. Histologic scoring of explanted fat grafts demonstrated no difference in quality between the irradiated and nonirradiated groups.

CONCLUSIONS

Fat grafting attenuates dermal collagen deposition and vessel depletion characteristic of radiation fibrosis. Although fat graft retention rates are significantly lower in irradiated than in nonirradiated tissue, the quality of retained fat between the groups is similar.

Xenotransplantation of human fetal adipose tissue: a model of in vivo adipose tissue expansion and adipogenesis

Obesity during childhood and beyond may have its origins during fetal or early postnatal life. At present, there are no suitable in vivo experimental models to study factors that modulate or perturb human fetal white adipose tissue (WAT) expansion, remodeling, development, adipogenesis, angiogenesis, or epigenetics. We have developed such a model. It involves the xenotransplantation of midgestation human WAT into the renal subcapsular space of immunocompromised SCID-beige mice. After an initial latency period of approximately 2 weeks, the tissue begins expanding. The xenografts are healthy and show robust expansion and angiogenesis for at least 2 months following transplantation. Data and cell size and gene expression are consistent with active angiogenesis. The xenografts maintain the expression of genes associated with differentiated adipocyte function. In contrast to the fetal tissue, adult human WAT does not engraft. The long-term viability and phenotypic maintenance of fetal adipose tissue following xenotransplantation may be a function of its autonomous high rates of adipogenesis and angiogenesis. Through the manipulation of the host mice, this model system offers the opportunity to study the mechanisms by which nutrients and other environmental factors affect human adipose tissue development and biology.

Processing technique for lipofilling influences adipose-derived stem cell concentration and cell viability in lipoaspirate

BACKGROUND

Autologous fat grafting is a highly used technique in plastic and reconstructive surgery. Several fat-processing techniques have been described, with centrifugation frequently touted as the optimal method. Processing is one factor important for maximizing cell viability and adipose-derived mesenchymal stem cell (ADSC) concentrations. This study compared two methods of fat preparation (centrifugation vs Telfa-rolling) to determine which technique results in the greatest degree of cell viability and ADSC concentration.

METHODS

Abdominal fat was harvested from five patients. Equal aliquots were divided and processed by both centrifugation and Telfa-rolling. Samples were analyzed for ADSC proportions via flow cytometry and cell viability using methylene blue-based cell counting. Paired t tests were performed on all samples, and a P value lower than 0.05 was considered statistically significant.

RESULTS

Telfa-rolling processing resulted in a higher percentage of isolated ADSCs (P < 0.5 for 3 of 4 parameters) and a significantly higher number of viable cells (P < 0.05).

CONCLUSION

Telfa-rolling results in a higher proportion of ADSCs and greater cell viability than centrifugation for donor adipose graft preparation. Further studies are necessary to confirm whether optimal preparation translates to improved augmentation and cell take at the recipient site.

LEVEL OF EVIDENCE IV

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