Fat Grafting and Adipose-Derived Regenerative Cells in Burn Wound Healing and Scarring: A Systematic Review of the Literature

New Frontiers in Skin Rejuvenation, Including Stem Cells and Autologous Therapies

One of the greatest challenges in the progression of aesthetic medicine lies in providing treatments with long-term results that are also minimally invasive and safe. Keeping up with this demand are developments in autologous therapies such as adipose-derived stem cells, stromal vascular fraction, microfat, nanofat, and platelet therapies, which are being shown to deliver satisfactory results. Innovations in more traditional cosmetic therapies, such as botulinum toxin, fillers, and thread lifts, are even more at the forefront of the advancement in aesthetics. Combining autologous therapies with traditional noninvasive methods can ultimately provide patients with more effective rejuvenation options.

Use of Condensed Nanofat Combined With Fat Grafts to Treat Atrophic Scars

Importance

In addition to the physical deformity, there is often great psychological burden of facial scars for patients. In this study, we use condensed nanofat combined with fat grafts in a novel technique to improve atrophic facial scars by raising both the surface and the bottom of the affected area.

Objective

To assess whether the use of condensed nanofat combined with fat grafting can be effective in treating atrophic facial scars from both an aesthetic and a functional perspective.

Design, Setting, and Participants

In this prospective case series of 20 patients with 25 atrophic facial scars, each scar was treated with condensed nanofat combined with fat grafts at the Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou, Zhejiang, China. Postoperative results were evaluated by the patients themselves and by 3 senior plastic surgeon observers.

Main Outcomes and Measures

Multiple preoperative and postoperative examinations included the use of the Patient and Observer Scar Assessment Scale (POSAS) to evaluate both the functional and aesthetic aspects of the atrophic facial scars. Punch biopsy specimens were stained for the presence of melanin, elastic fibers, and cytokeratin (CK) 14 and CK19. Images were analyzed using ImageJ software, and the data were analyzed by paired sample t test.

Results

Twenty patients (6 men and 14 women; mean age, 38.25 years; age range, 21-62 years) with a total of 25 atrophic facial scars were treated between March 2014 and December 2016. The patients' mean (SD) scar assessment scores were significantly decreased postoperatively in the final examination for color, 6.40 (0.51) vs 2.40 (0.24) (P < .001); stiffness, 7.20 (0.37) vs 3.20 (0.20) (P < .001); thickness, 5.80 (0.73) vs 1.80 (0.37) (P = .001); and irregularity, 5.20 (0.49) vs 2.20 (0.37) (P = .003); and the observers' scores were also significantly decreased for pigmentation, 4.40 (0.51) vs 2.00 (0.32) (P = .004); thickness, 3.00 (0.32) vs 1.80 (0.20) (P = .03); relief, 4.40 (0.51) vs 2.40 (0.24) (P = .003); and pliability, 4.20 (0.37) vs 1.40 (0.24) (P < .001). In the final follow-up examinations, a significantly improved overall POSAS score was found among both patients, 28.80 (1.02) vs 12.20 (0.80) (P < .001), and observers, 18.00 (0.71) vs 9.20 (0.37) (P = .001). Enhancement of Fontana-Masson staining of melanin in the basal cell layer was observed postoperatively, and a significant postoperative change was detected for the mean (SD) values of average optical density from the preoperative measurement, 0.671 (0.083) vs 0.844 (0.110) (P = .01). The sebaceous glands and sweat glands that were not found in the preoperative images were seen postoperatively by immunohistochemical staining with CK14 and CK19.

Conclusions and Relevance

Our preliminary clinical and pathological results indicate that the use of condensed nanofat combined with fat grafts may be an effective approach to treating atrophic facial scars from both an aesthetic and a functional perspective.

Level of Evidence

4.

Adipose-derived stem cells-induced burn wound healing and regeneration of skin appendages in a novel skin island rat model

BACKGROUND

The study of effectiveness of adipose-derived stem cells (ASCs) in treating burn wounds is still a developing field. The process of wound contraction in areas of loose skin is a major confounding factor in the evaluation and study of burn wound healing in animal models.

METHODS

To evaluate the effect of local ASCs administration, deep partial thickness burn wounds were induced by 30 s application of hot copper plates in a novel skin island burn wound rat model to avoid interference from primary wound contraction. Skin islands were divided into two treatment groups-control group (n = 9) injected with PBS and ASCs-treated group (n = 9) injected with 5 × 10 ASCs intradermally. Progress in wound healing was checked at regular intervals after injury (on 1st, 2nd, 3rd, and 4th week) by measuring the mean wound area and analyzing the wound histologically and immunohistochemically, after unstitching the overlaying skin to expose the skin island.

RESULTS

It was found that local intradermal injection of ASCs improved burn wound healing at all given time points when compared with control groups, especially in the first 2 weeks (p < 0.05). The percentage of live follicles increased gradually in the ASCs-treated groups compared with control groups between the 3rd and 4th weeks (p < 0.05). The vascular density and proliferating cell nuclear antigen index were also significantly increased in the ASCs-treated groups.

CONCLUSION

Thus, in this study, a novel burn wound rat model with reduced interference from wound contraction has been put forth to investigate the therapeutic effects of local administration of ASCs on burn wound healing. Local injection of ASCs not only improved burn wound recovery but also enhanced angiogenesis and skin appendage regeneration.

Wound healing and fibrosis: current stem cell therapies

Scarring is a result of the wound healing response and causes tissue dysfunction after injury. This process is readily evident in the skin, but also occurs internally across organ systems in the form of fibrosis. Stem cells are crucial to the innate tissue healing response and, as such, present a possible modality to therapeutically promote regenerative healing while minimizing scaring. In this review, the cellular basis of scaring and fibrosis is examined. Current stem cell therapies under exploration for skin wound healing and internal organ fibrosis are discussed. While most therapeutic approaches rely on the direct application of progenitor-type cells to injured tissue to promote healing, novel strategies to manipulate the scarring response are also presented. As our understanding of developmental and stem cell biology continues to increase, therapies to encourage regeneration of healthy functional tissue after damage secondary to injury or disease will continue to expand.

The Preparation of the Recipient Site in Fat Grafting: A Comprehensive Review of the Preclinical Evidence

BACKGROUND

Several methods to prepare the recipient site in fat grafting have been proposed in recent decades. However, to date, these procedures have never been reviewed exhaustively. The purpose of the present study is to provide a comprehensive overview of the different techniques to prepare the recipient site for fat grafting as they were investigated in preclinical studies, with resulting outcomes and underlying mechanisms of action.

METHODS

The PubMed/MEDLINE database was queried to search for preclinical investigations on the preparation of the recipient site in fat grafting using the following algorithm: ((recipient site) AND (fat grafting) OR (lipofilling) OR (lipograft)). A priori criteria were applied to review the resulting articles.

RESULTS

Thirteen animal studies met inclusion criteria. Overall, five techniques were identified: external volume expansion, implantation of alloplastic material (silicone sheets), administration of cell-proliferation factors (i.e., vascular endothelial growth factor, adipose tissue-derived stromal vascular fraction, and interleukin-8), ischemia, and microneedling. A positive effect on cellular activity (cell proliferation and angiogenesis) was demonstrated by all studies and achieved with all techniques. Seven of the eight authors who examined this aspect reported enhancement of fat graft survival.

CONCLUSIONS

Improvement of fat grafting surgical outcomes is documented preclinically using different recipient-site preparation techniques, particularly through enhancement of vascularization and soft-tissue expansion. This understanding will lead to further clinical research, especially for those cases where improvement of the recipient site is recommended, such as contracted scars or preirradiated tissues.

Skin tissue regeneration for burn injury

The skin is the largest organ of the body, which meets the environment most directly. Thus, the skin is vulnerable to various damages, particularly burn injury. Skin wound healing is a serious interaction between cell types, cytokines, mediators, the neurovascular system, and matrix remodeling. Tissue regeneration technology remarkably enhances skin repair via re-epidermalization, epidermal-stromal cell interactions, angiogenesis, and inhabitation of hypertrophic scars and keloids. The success rates of skin healing for burn injuries have significantly increased with the use of various skin substitutes. In this review, we discuss skin replacement with cells, growth factors, scaffolds, or cell-seeded scaffolds for skin tissue reconstruction and also compare the high efficacy and cost-effectiveness of each therapy. We describe the essentials, achievements, and challenges of cell-based therapy in reducing scar formation and improving burn injury treatment.

Combined Non-Ablative Laser and Microfat Grafting for Burn Scar Treatment

BACKGROUND

Burn scar treatment persists as an unsolved problem, involving thousands of affected patients disfigured for life.

OBJECTIVES

We sought to present our experience with the use of combined treatments for patients with burn scars.

METHODS

This was a case series report of the senior author's experience during 8 years utilizing the combined treatments of Fraxel Restore (fractional laser) and microfat graft injection for 288 patients with burn scars.

RESULTS

Laser treatment reduced scar intensity and attenuated skin irregularities and hyperpigmentation. All patients demonstrated marked improvement of skin texture and an increase in scar softness after 3 sessions of microfat grafting. However, the degree of improvement varied between patients and was related to the severity of the scar and the type of tissue. Overall, a 40% to 80% improvement was noted in our patients. All patients and their families expressed satisfaction with the results.

CONCLUSIONS

The combined treatment of Fraxel and microfat grafting is an effective technique for improving the appearance of a hypertrophic scar or keloid on burn patients. Fat tissue stem cells may have helped to repair the damaged skin.

LEVEL OF EVIDENCE: 4

The Influence of Fat Grafting on Skin Quality in Cosmetic Foot Grafting: A Randomized, Cross-Over Clinical Trial

BACKGROUND

Pedal fat grafting is a cosmetic procedure to treat the functional and aesthetic sequelae of pedal fat pad atrophy. Fat grafting has been found to mitigate these symptoms, but the exact mechanism is unknown.

OBJECTIVES

The authors hypothesized that pedal fat grafting may improve skin quality, accounting for prolonged symptomatic improvement despite loss of grafted fat.

METHODS

Patients with pedal atrophy were enrolled in a randomized crossover clinical trial. Group 1 underwent fat grafting upon enrollment with 2-year follow-up. Group 2 was managed conservatively for 1 year then placed into the fat grafting group with 1-year follow-up. Patients underwent pedal ultrasounds to determine thicknesses of the fat pad and dermis, and photographs were taken to assess skin quality.

RESULTS

Three men and 20 women with an average age of 63 ± 6 years and an average BMI of 26.0 ± 4.6 kg/m2 were enrolled in the study. Twenty-six feet were injected in Group 1 and 17 were injected in Group 2. Group 1 dermal thickness increased at 6 months post-injection (P < 0.05). This increase persisted through 24 months. Group 2 dermal thickness decreased prior to injection (P < 0.05) but returned to baseline after injection and through 12-month follow-up (P < 0.05). Fat pad thickness returned to baseline by study completion in both groups (P < 0.05).

CONCLUSIONS

Pedal fat grafting yielded a significant, sustained increase in dermal thickness, though grafted fat was not retained. Fat grafting may improve skin quality, which could contribute to improved clinical outcomes despite loss of grafted fat.

LEVEL OF EVIDENCE: 2

Influence of Adipose Tissue-Derived Stem Cells on the Burn Wound Healing Process

Burns are lesions in which the thermal energy of the causative agent transfers heat to the surface of the body, causing superficial or deep damage to the skin with protein denaturation in cells and biochemical maladjustments, which delay and disrupt the cicatricial process, increasing the chances of functional and aesthetic sequelae. This study evaluates the influence of adipose tissue-derived stem cells (ADSCs) on burn healing in terms of the size of the cicatricial space and quantified measures of collagen deposition, inflammatory infiltrate, blood vessels, and lymphatic vessels. Initially, intra-abdominal adipose tissue was resected from a single donor Wistar rat that was not part of any of the subsequent groups to obtain ADSCs by isolation and cell culture. Burns were made in the left lateral abdominal region of Wistar rats by contact with a square ceramic paper with a 484 mm² area heated to 100°C for 30 seconds. Intradermal ADSC transplantation was performed in two stages. The first was on the same day of the burn, when 3.2 × 10⁶ ADSCs were transplanted shortly after the burned region cooled, while the second stage occurred four days later with the same number of ADSCs. The progress was evaluated by immunohistochemical methods and H&E, Masson's trichrome, Picrosirius red, and Lyve-1 immunofluorescence staining. Despite the quantitative similarity of blood vessels and the inflammatory infiltrate observed by H&E, there were statistically significant differences between the groups on the fourteenth day of evolution. The group that received ADSCs showed a reduction in the scar tissue area, increased collagen type III deposition, and a quantifiable reduction in lymphatic vessels, so we conclude that ADSCs influence the healing of total thickness burns in rats.

Novel pharmacotherapy for burn wounds: what are the advancements

INTRODUCTION

The prognosis for severe burns has improved significantly over the past 50 years. Meanwhile, burns have become an affliction mainly affecting the less well-developed regions of the world. Early excision and skin grafting has led to major improvements in therapeutic outcomes.

AREAS COVERED

The purpose of this article is to survey the use of pharmacotherapy to treat different pathophysiological complications of burn injury. The author, herein, discusses the use of drug treatments for a number of systemic metabolic disturbances including hyperglycemia, elevated catabolism, and gluconeogenesis.

EXPERT OPINION

Advancements in personalized and molecular medicine will make an impact on burn therapy. Similarities between severe burns and other critically ill patients will lead to cross-fertilization between different medical specialties. Furthermore, advances in stem cells and tissue regeneration will lead to improved healing and less lifelong disability. Indeed, research in new drug therapy for burns is actively progressing for many different complications.

Exosomes from hypoxia-treated human adipose-derived mesenchymal stem cells enhance angiogenesis through VEGF/VEGF-R

BACKGROUND

We previously reported that co-transplantation of exosomes from hypoxia-preconditioned adipose mesenchymal stem cells (ADSCs) improves the neoangiogenesis and survival of the grafted tissue. This study aimed to investigate the molecular mechanism of this protective effect.

METHODS

Exosomes were collected from normoxia-treated (nADSC-Exo) or hypoxia--treated (hypADSC-Exo) human ADSCs, and their pro-angiogenic capacity was evaluated in human umbilical vein endothelial cells (HUVECs) and a nude mouse model of subcutaneous fat grafting. Protein array was used to compare the exosome-derived proteins between nADSC-Exo and hypADSC-Exo.

RESULTS

Compared with the nADSC-Exo group and untreated control, hypADSC-Exo treatment significantly promoted proliferation, migration and tube-formation capability of HUVECs. Protein array revealed that the levels of vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), fibroblast growth factor (FGF) and their receptors (VEGF-R2, VEGF-R3), and monocyte chemoattractant protein 2 (MCP-2), monocyte chemoattractant protein 4 (MCP-4) were significantly higher in the hypADSC-Exo than in the nADSC-Exo. In the nude mice model of fat grafting, immunofluorescence of CD31 showed that hypADSC-Exo dramatically improved neovascularization around the graft. Furthermore, compared with nADSC-Exo and control groups, cotransplantation of hypADSC-Exo significantly increased the protein expression of EGF, FGF, VEGF/VEGF-R, angiopoietin-1(Ang-1) and tyrosine kinase with immunoglobulin-like and EGF-like domains 1(Tie-1, an angiopoietin receptor) in the grafted tissue at 30 days after transplantation. Immunohistochemical analysis demonstrated that hypADSC-Exo treatment significantly increased VEGF-R expression in the grafted tissue.

CONCLUSIONS

Exosomes from hypoxia-treated human ADSCs possess a higher capacity to enhance angiogenesis in fat grafting, at least partially, via regulating VEGF/VEGF-R signaling.

Mechanical micronization of lipoaspirates for the treatment of hypertrophic scars

Background

Hypertrophic scars cause cosmetic and functional problems for patients, and their treatment remains challenging. Mechanical micronization of adipose tissue can remove adipocytes and concentrate functional cells. Stromal vascular fraction (SVF)-gel is obtained by a series of simple mechanical processes, including shifting between syringes and centrifugation. This study aimed to assess the therapeutic effect of SVF-gel on hypertrophic scars.

Methods

A model of hypertrophic scars was established in rabbit ears. SVF-gel and SVF cells were obtained from rabbit inguinal fat pads and injected into scars. Phosphate-buffered saline (PBS) was used as a control. Scars were structurally characterized by histologic and immunohistochemical analyses. Expression of inflammatory and fibrogenic genes was evaluated.

Results

Hypertrophic scars became less visible and softer following injection of SVF-gel or SVF cells. Dermal thickness was significantly lower in the groups treated with SVF-gel and SVF cells than in the PBS-treated group. Treatment with SVF-gel restored subcutaneous fat tissue in scars, while treatment with SVF cells and PBS did not. Injection of SVF-gel and SVF cells reduced macrophage infiltration in the dermal layer and decreased mRNA expression of interleukin-6 and monocyte chemoattractant protein-1. In addition, the level of myofibroblasts and collagen deposition were reduced in the groups treated with SVF-gel and SVF cells.

Conclusions

SVF-gel has therapeutic effects on hypertrophic scars. Injection of SVF-gel into hypertrophic scars restores subcutaneous fat tissue and reduces the levels of macrophages and myofibroblasts; thus, it decreased the dermal thickness of the scar.

Isolation of Stromal Vascular Fraction by Fractionation of Adipose Tissue

Adipose tissue-derived stromal cells (ASCs) are a promising candidates for cellular therapy in the field of regenerative medicine. ASCs are multipotent mesenchymal stem cell-like and reside in the stromal vascular fraction (SVF) of adipose tissue with the capacity to secrete a plethora of pro-regenerative growth factors. Future applications of ASCs may be restricted through (trans)national governmental policies that do not allow for use of nonhuman-derived (non-autologous) enzymes to isolate ASC. Besides, enzymatic isolation procedures are also time consuming. To overcome this issue, nonenzymatic isolation procedures to isolate ASCs or the SVF are being developed, such as the fractionation of adipose tissue procedure (FAT). This standardized procedure to isolate the stromal vascular fraction can be performed within 10-12 min. The short procedure time allows for intraoperative isolation of 1 mL of stromal vascular fraction derived from 10 mL of centrifuged adipose tissue. The stromal vascular fraction mostly contains blood vessels, extracellular matrix, and ASCs. However, based on the histological stainings an interdonor variation exists which might result in different therapeutic effects. The existing interdonor variations can be addressed by histological stainings and flow cytometry.

Autologous fat grafting: Latest insights

A recent rise in the use of autologous fat transfer for soft tissue augmentation has paralleled the increasing popularity of liposuction body contouring. This creates a readily available and inexpensive product for lipografting, which is the application of lipoaspirated material. Consistent scientific proof about the long-term viability of the transferred fat is not available. Clinically, there is a reabsorption rate which has been reported to range from 20 to 90%. Results can be unpredictable with overcorrection and regular need for additional interventions. In this review, adipogenesis physiology and the adipogenic cascade from adipose-derived stem cells to adult adipocytes is extensively described to determine various procedures involved in the fat grafting technique. Variables in structure and physiology, adipose tissue harvesting- and processing techniques, and the preservation of fat grafts are taken into account to collect reproducible scientific data to establish standard in vitro and in vivo models for experimental fat grafting. Adequate histological staining for fat tissue, immunohistochemistry and viability assays should be universally used in experiments to be able to produce comparative results. By analysis of the applied methods and comparison to similar experiments, a conclusion concerning the ideal technique to improve clinical outcome is proposed.

•

Adipogenic physiology is described to determine various procedures involved in the fat grafting technique.

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Clinical studies on fat grafting have confirmed an unpredictable result.

•

After analysis of the literature and despite attempts to eliminate confounding factors, on every step of the fat transfer technique a number of studies with conflicting results exist.

•

Adequate histological staining for fat tissue, immunohistochemistry and viability assays should be universally used in experiments to be able to produce comparative results.

Protocol for a systematic review of autologous fat grafting for wound healing

BACKGROUND

Autologous fat grafting is an emerging therapeutic option for cutaneous wounds. The regenerative potential of autologous fat relates to the presence of adipose-derived stem cells (ADSCs) within the stromal vascular fraction (SVF). ADSCs are capable of differentiating into fibroblasts and keratinocytes, as well as secreting soluble mediators with angiogenic and anti-inflammatory properties. However, to date, there has been no comprehensive assessment of the wound healing literature in humans. This systematic review aims to critically evaluate the efficacy and safety of autologous fat grafting in acute and chronic cutaneous wounds with an appraisal of the quality of evidence available.

METHODS

Following PRISMA guidelines, MEDLINE, Embase and Cochrane Library databases will be searched from inception to December 2017. All primary clinical studies in which wounds are treated with lipotransfer, cell-assisted lipotransfer (CAL), SVF products or isolated ADSCs will be eligible for inclusion. Study screening and data extraction will be conducted by two authors in duplicate. Our primary outcome measure will be the proportion of completely healed wounds at 12 weeks. Secondary outcome measures will include the proportion of partially healed wounds at 12 weeks; the mean wound surface area reduction at 12 weeks; the mean time to wound healing; and adverse event rates. The quality of evidence for each summary outcome measure will be assessed using the GRADE approach.

DISCUSSION

In light of the growing popularity of autologous fat grafting for wound healing, a systematic appraisal of the available evidence is timely. If autologous fat grafting is associated with a positive treatment effect, we will compare these outcomes to those achieved using alternative wound management strategies. This review also aims to determine if one or more autologous fat grafting techniques are superior and whether this varies according to patient- and wound-specific factors. We anticipate that these results will guide future research and inform clinical practice.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017081499.

Fat Grafting Can Induce Browning of White Adipose Tissue

Background

Fat grafting is commonly used when treating soft-tissue defects. However, much of the basic biology behind fat transfer is still uncovered. Adipocytes can be divided into energy storing white and energy burning brown adipose cells. It is now well known, that also adult humans have metabolically active brown adipose tissue (BAT) within white adipose tissue (WAT). Previously our group showed that transfer of metabolically inactive WAT into a new environment increased the metabolic activity of the fat grafts to resemble the activity in the recipient site and that different WAT depots have variation in the metabolic activity. This led us to speculate, whether the metabolic increase of the graft is a result of "browning" of the transferred WAT toward beige adipose tissue.

Methods

We investigated the metabolic and histological characteristics and BAT marker Ucp1 gene expression in different types of WAT grafts placed either in subcutaneous or muscle tissue in mice. Metabolic activity of the grafts was investigated by FDG-PET/CT at 4- and 12-week time-points.

Results

The glucose uptake of all transferred fat types was increased when compared with respective control WAT regardless of transfer location. Ucp1 gene and protein expression was increased in 4 of 15 intramuscularly placed fat graft samples and showed histological resemblance to BAT with multilocular cells.

Conclusions

Grafting of metabolically inactive fat intramuscularly may induce browning of fat grafts toward more active beige adipose tissue. This opens up new research areas in exploiting fat grafting in metabolic diseases.

Autologous and not allogeneic adipose-derived stem cells improve acute burn wound healing

Adipose-derived stem cells (ADSCs) transplant has been reported to be a potential treatment for burn wounds. However, the effects of autogenicity and allogenicity of ADSCs on burn wound healing have not been investigated and the method for using ADSCs still needs to be established. This study compared the healing effects of autologous and allogenic ADSCs and determined an optimal method of using ADSCs to treat acute burn wounds. Experiments were performed in 20 male Wistar rats (weight, 176-250 g; age, 6-7 weeks). Two identical full-thickness burn wounds (radius, 4 mm) were created in each rat. ADSCs harvested from inguinal area and characterized by their high multipotency were injected into burn wounds in the original donor rats (autologous ADSCs group) or in other rats (allogenic ADSCs group). The injection site was either the wound center or the four corners 0.5 cm from the wound edge. The reduction of burn surface areas in the two experimental groups and in control group were evaluated with Image J software for 15 days post-wounding to determine the wound healing rates. Wound healing was significantly faster in the autologous ADSCs group compared to both the allogenic ADSCs group (p<0.05) and control group (p<0.05). Wound healing in the allogenic ADSC group did not significantly differ from that in control group. Notably, ADSC injections 0.5cm from the wound edge showed significantly improved healing compared to ADSCs injections in the wound center (p<0.05). This study demonstrated the therapeutic efficacy of ADSCs in treating acute burn wounds in rats. However, only autologous ADSCs improved healing in acute burn wounds; allogenic ADSCs did not. This study further determined a superior location of using ADSCs injections to treat burn wounds including the injection site. Future studies will replicate the experiment in a larger and long-term scale burn wounds in higher mammalian models to facilitate ADSCs therapy in burn wound clinical practice.

Adipose tissue stem cells in regenerative medicine

Adipose tissue-derived stem cells (ADSCs) are mesenchymal cells with the capacity for self-renewal and multipotential differentiation. This multipotentiality allows them to become adipocytes, chondrocytes, myocytes, osteoblasts and neurocytes among other cell lineages. Stem cells and, in particular, adipose tissue-derived cells, play a key role in reconstructive or tissue engineering medicine as they have already proven effective in developing new treatments. The purpose of this work is to review the applications of ADSCs in various areas of regenerative medicine, as well as some of the risks associated with treatment with ADSCs in neoplastic disease.

Extracellular matrix/stromal vascular fraction gel conditioned medium accelerates wound healing in a murine model

Conditioned medium (CM) is a new treatment modality in regenerative medicine and has shown a successful outcome in wound healing. We recently introduced extracellular matrix/stromal vascular fraction gel (ECM/SVF-gel), an adipose-derived stem cell and adipose native extracellular matrix-enriched product for cytotherapy. This study aimed to evaluate the effect of CM from ECM/SVF-gel (Gel-CM) on wound healing compared with the conventional CM from adipose tissue (Adi-CM) and stem cell (SVF-CM). In vitro wound healing effect of three CMs on keratinocytes and fibroblasts was evaluated in terms of proliferation property, migratory property, and extracellular matrix production. In vivo, two full-thickness wounds were created on the back of each mice. The wounds were randomly divided to receive Gel-CM, Adi-CM, SVF-CM, and PBS injection. Histologic observations and collagen content of wound skin were made. Growth factors concentration in three CMs was further quantified. In vitro, Gel-CM promoted the proliferation and migration of keratinocytes and fibroblasts and enhanced collagen I synthesis in fibroblasts compared to Adi-CM and SVF-CM. In vivo, wound closure was faster, and dermal and epidermal regeneration was improved in the Gel-CM-treated mice compared to that in Adi-CM and SVF-CM-treated mice. Moreover, The growth factors concentration (i.e., vascular endothelial growth factor, basic fibroblast growth factor, hepatocyte growth factor, and transforming growth factor-β) in Gel-CM were significantly higher than those in Adi-CM and SVF-CM. Gel-CM generated under serum free conditions significantly enhanced wound healing effect compared to Adi-CM and SVF-CM by accelerating cell proliferation, migration, and production of ECM. This improved trophic effect may be attributed to the higher growth factors concentration in Gel-CM. Gel-CM shows potential as a novel and promising alternative to skin wound healing treatment. But limitations include the safety and immunogenicity studies of Gel-CM still remain to be clearly clarified and more data on mechanism study are needed.

The Impact of Recipient Site External Expansion in Fat Grafting Surgical Outcomes

BACKGROUND

The fat grafting process includes the 4 phases of tissue harvesting, processing, recipient-site preparation, and reinjection. Among them, the preparation of the recipient site has never been exhaustively reviewed. We aim to provide a comprehensive overview of the methods to prepare the recipient site through external expansion with the resulting outcomes.

METHODS

PubMed/Medline database was searched for studies on fat grafting recipient site preparation by applying the following algorithm: ((fat grafting) OR (lipofilling) OR (lipograft) AND (recipient site)). A priori criteria were used to review the resulting articles and identify those dealing with external expansion.

RESULTS

Fourteen studies published from 2008 through 2016 met inclusion criteria (4 case reports, 6 retrospective, and 4 prospective studies), representing 1,274 treated patients. Two devices for preexpansion were used with different protocols: BRAVA system and Kiwi VAC-6000M with a PalmPump. The 13 studies that applied the BRAVA system reported large fat volume transplantation to the breast (average > 200 cc). The most common complications were localized edema (14.2%), temporary bruising, and superficial skin blisters (11.3%), while the most serious was pneumothorax (0.5%). The majority of the studies reported enhancement of fat graft survival, which ranged between 53% and 82% at 6 months to 1 year follow-up, and high satisfaction of patients and surgeon.

CONCLUSIONS

External expansion and fat grafting is a promising technique for breast reconstruction and augmentation. However, due to the overall low level of evidence of the available studies, further research is needed to validate the procedure.

Burn injury: Challenges and advances in burn wound healing, infection, pain and scarring

Severe burn injuries are the most traumatic and physically debilitating injuries affecting nearly every organ system and leading to significant morbidity and mortality. Early burn wound excision and skin grafting are common clinical practices that have significantly improved the outcomes for severe burn injured patients by reducing mortality rate and days of hospital stay. However, slow wound healing, infection, pain, and hypertrophic scarring continue to remain a major challenge in burn research and management. In the present article, we review and discuss issues in the current treatment of burn injuries; the advances and novel strategies developed in the past decade that have improved burn management; and also, pioneer ideas and studies in burn research which aims to enhance burn wound care with a focus on burn wound infection, pain management, treatments for scarring and skin tissue engineering.

Autologous Adipose-Derived Stem Cells Reduce Burn-Induced Neuropathic Pain in a Rat Model

Background: Burn scar pain is considered as neuropathic pain. The anti-inflammation and anti-neuroinflammation effects of adipose-derived stem cells (ASCs) were observed in several studies. We designed a study using a murine model involving the transplantation of autologous ASCs in rats subjected to burn injuries. The aim was to detect the anti-neuroinflammation effect of ASC transplantation and clarify the relationships between ASCs, scar pain, apoptosis and autophagy. Methods: We randomized 24 rats into 4 groups as followings: Group A and B, received saline injections and autologous transplantation of ASCs 4 weeks after sham burn, respectively; Group C and D, received saline injections and autologous transplantation 4 weeks after burn injuries. A designed behavior test was applied for pain evaluation. Skin tissues and dorsal horn of lumbar spinal cords were removed for biochemical analysis. Results: ASC transplantation significantly restored the mechanical threshold reduced by burn injury. It also attenuated local inflammation and central neuroinflammation and ameliorated apoptosis and autophagy in the spinal cord after the burn injury. Conclusion: In a rat model, autologous ASC subcutaneous transplantation in post-burn scars elicited anti-neuroinflammation effects locally and in the spinal cord that might be related to the relief of post-burn neuropathic pain and attenuated cell apoptosis. Thus, ASC transplantation post-burn scars shows the potential promising clinical benefits.

The science behind autologous fat grafting

INTRODUCTION

Adipose grafting has undergone significant changes over time. Many different techniques have been followed by trying to improve the quality of the lipoaspirate and the survival of the fat graft after implantation.

MATERIAL AND METHODS

The purpose of this review is to analyse the historical evolution of the surgical harvesting and implant technique, describing the changes that have brought significant improvements, revolutionizing the aesthetic and functional results obtainable.

RESULTS

A standard fat grafting technique is commonly performed in three stages: harvesting of adipose tissue from a suitable donor site; processing of the lipoaspirate to eliminate cellular debris, acellular oil and excess of infiltrated solution, reinjection of the purified adipose tissue. The most widely used surgical technique was described by Coleman. He modified and corrected the methods and results of his predecessors and proposed an atraumatic protocol for the treatment of adipose tissue.He reported that the key to successful fat grafting lies in the technique. In addition, he noticed that adipose tissue was not only a good filler, but improved the quality of the skin. In fact, fat grafts demonstrated to have not only dermal filler properties but also regenerative potential owing to the presence of stem cells in fat tissue.

CONCLUSION

Adipose tissue, actually, is the closest to the ideal filler because it is readily available; easily obtainable, with low donor-site morbidity; repeatable; inexpensive; versatile; and biocompatible. There is an abundance of literature supporting the efficacy of fat grafting in both aesthetic and reconstructive cases. Recent studies have shown the utility of adipose-derived stem cells in the improvement of wound healing, describing their ability to regenerate soft tissues and their remodelling capacity provided by their unique cytokine and growth factor profiles.Despite ongoing concerns about survival and longevity of fat grafts after implantation and unpredictability of long-term outcome, fat has been successfully used as a filler in many differ clinic situation.

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.

Can regenerative medicine and nanotechnology combine to heal wounds? The search for the ideal wound dressing

Skin is the outermost covering of the human body and at the same time the largest organ comprising 15% of body weight and 2 m2 surface area. Skin plays a key role as a barrier against the outer environment depending on its thickness, color and structure, which differ from one site to another. The four major types of problematic wounds include ulcers (diabetic, venous, pressure) and burn wounds. Developing novel dressings helps us to improve the wound healing process in difficult patients. Recent advances in regenerative medicine and nanotechnology are revolutionizing the field of wound healing. Antimicrobial activity, exogenous cell therapy, growth factor delivery, biodegradable and biocompatible matrix construction, all play a role in hi-tech dressing design. In the present review, we discuss how the principles of regenerative medicine and nanotechnology can be combined in innovative wound dressings.

Adipose Extracellular Matrix/Stromal Vascular Fraction Gel Secretes Angiogenic Factors and Enhances Skin Wound Healing in a Murine Model

Mesenchymal stem cells are an attractive cell type for cytotherapy in wound healing. The authors recently developed a novel, adipose-tissue-derived, injectable extracellular matrix/stromal vascular fraction gel (ECM/SVF-gel) for stem cell therapy. This study was designed to assess the therapeutic effects of ECM/SVF-gel on wound healing and potential mechanisms. ECM/SVF-gel was prepared for use in nude mouse excisional wound healing model. An SVF cell suspension and phosphate-buffered saline injection served as the control. The expression levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and monocyte chemotactic protein-1 (MCP-1) in ECM/SVF-gel were analyzed at different time points. Angiogenesis (tube formation) assays of ECM/SVF-gel extracts were evaluated, and vessels density in skin was determined. The ECM/SVF-gel extract promoted tube formation in vitro and increased the expression of the angiogenic factors VEGF and bFGF compared with those in the control. The expression of the inflammatory chemoattractant MCP-1 was high in ECM/SVF-gel at the early stage and decreased sharply during the late stage of wound healing. The potent angiogenic effects exerted by ECM/SVF-gel may contribute to the improvement of wound healing, and these effects could be related to the enhanced inflammatory response in ECM/SVF-gel during the early stage of wound healing.

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.

Autologous fat grafting in keloids and hypertrophic scars: a review

Keloid and hypertrophic scars are unique human dermal fibroproliferative disorders of the injured skin and are associated with pain, itch and can cause functional limitations. A number of genetic, systemic and local factors have been identified in the formation of keloids and hypertrophic scars. Studies have shown that adipose-derived stem cells have angiogenic and antiapoptotic properties which has effects on wound healing, soft-tissue restoration and scar remodelling, and thus may have a role in managing keloid scaring. However, this role is not well described in the literature. A systemic review of available literature was thus undertaken, regarding the use of fat grafting in treatment of keloids and hypertrophic scarring. In total, 858 articles were identified, with ten studies ultimately fulfilling inclusion criteria. There were no studies specifically isolating the keloids and hypertrophic group of patients, and thus quantitative data were completely lacking from the literature. There were, however, individual cases described, and qualitatively encouraging clinical results were reported for the use of fat grafting on keloids and hypertrophic scars. Combined with the current theoretical and immunohistochemical understanding through other laboratory and animal studies, fat grafting may play a role in the treatment of keloids and hypertrophic scaring; however, specific evidence is currently lacking. The role for further research is clear.

Keloid and hypertrophic scars are difficult to treat conditions. Some studies have suggested that fat cells may have a role in managing these scars although this role is not well described in the literature. We perform a systematic review of available literature, examining the evidence for this.

Skin Tissue Engineering: Application of Adipose-Derived Stem Cells

Perception of the adipose tissue has changed dramatically over the last few decades. Identification of adipose-derived stem cells (ASCs) ultimately transformed paradigm of this tissue from a passive energy depot into a promising stem cell source with properties of self-renewal and multipotential differentiation. As compared to bone marrow-derived stem cells (BMSCs), ASCs are more easily accessible and their isolation yields higher amount of stem cells. Therefore, the ASCs are of high interest for stem cell-based therapies and skin tissue engineering. Currently, freshly isolated stromal vascular fraction (SVF), which may be used directly without any expansion, was also assessed to be highly effective in treating skin radiation injuries, burns, or nonhealing wounds such as diabetic ulcers. In this paper, we review the characteristics of SVF and ASCs and the efficacy of their treatment for skin injuries and disorders.

The power of fat and its adipose-derived stromal cells: emerging concepts for fibrotic scar treatment

Lipofilling or lipografting is a novel and promising treatment method for reduction or prevention of dermal scars after injury. Ample anecdotal evidence from case reports supports the scar‐reducing properties of adipose tissue grafts. However, only a few properly controlled and designed clinical trials have been conducted thus far on this topic. Also, the underlying mechanism by which lipofilling improves scar aspect and reduces neuropathic scar pain remains largely undiscovered. Adipose‐derived stromal or stem cells (ADSC) are often described to be responsible for this therapeutic effect of lipofilling. We review the recent literature and discuss anticipated mechanisms that govern anti‐scarring capacity of adipose tissue and its ADSC. Both clinical and animal studies clearly demonstrated that lipofilling and ADSC influence processes associated with wound healing, including extracellular matrix remodelling, angiogenesis and modulation of inflammation in dermal scars. However, randomized clinical trials, providing sufficient level of evidence for lipofilling and/or ADSC as an anti‐scarring treatment, are lacking yet warranted in the near future. © 2017 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd

Mesenchymal Stem Cells from Adipose Tissue in Clinical Applications for Dermatological Indications and Skin Aging

Operating at multiple levels of control, mesenchymal stem cells from adipose tissue (ADSCs) communicate with organ systems to adjust immune response, provide signals for differentiation, migration, enzymatic reactions, and to equilibrate the regenerative demands of balanced tissue homeostasis. The identification of the mechanisms by which ADSCs accomplish these functions for dermatological rejuvenation and wound healing has great potential to identify novel targets for the treatment of disorders and combat aging. Herein, we review new insights into the role of adipose-derived stem cells in the maintenance of dermal and epidermal homeostasis, and recent advances in clinical applications of ADSCs related to dermatology.

Autologous fat grafting for scars, healing and pain: a review

INTRODUCTION

Current guidelines suggest a multimodal approach to treating scars but there is no gold standard for treatment; however, there is exciting therapeutic potential for the use of autologous fat grafting (AFG). Functional and aesthetic improvements have been reported, including pain relief and scar quality improvement.

AIMS

To explore the current evidence regarding the use of AFG in hypertrophic and painful scars.

METHODS

A systematic review of the literature was conducted using 11 MeSH terms in PubMed, Medline and EMBASE. English studies that used AFG to treat scars in human participants were included.

RESULTS

A total of 746 studies were found and 23 studies (from 2008 to 2016) were included: five studies were evidence level V; nine studies were evidence level IV; eight were evidence level III; and one study was evidence level II. A total of 1158 patients were assessed for improvement in scar characteristics including colour, thickness, volume, pain and restoration of function at affected sites, following treatment. Positive outcomes were noted for all parameters and a significant improvement in AFG's analgesic effect was recorded in 567 out of 966 patients, P < 0.05.

DISCUSSION

AFG is a minimally invasive and safe approach to treating scars, a promising alternative to surgical excision. The technique of blunt cannula insertion optimises the release of scar retraction, which contributes to the analgesic effect of this treatment method. The evidence supports current theories of mesenchymal stem cell's regenerative and anti-inflammatory properties responsible for scar healing. There are limited high quality studies to support its use and future randomised controlled trials should be conducted.

Shift toward Mechanical Isolation of Adipose-derived Stromal Vascular Fraction: Review of Upcoming Techniques

Standard isolation of adipose stromal vascular fraction (SVF) requires the use of collagenase and is considered more than “minimally manipulated” by current good manufacturing practice requirements. Alternatively, nonenzymatic isolation methods have surfaced using physical forces to separate cells from the adipose matrix. The purpose of this study was to review the literature on the use of mechanical isolation protocols and compare the results. The implication for use as a standard procedure in practice is discussed.

Multidisciplinary approaches to stimulate wound healing

New civil wars and waves of terrorism are causing crucial social changes, with consequences in all fields, including health care. In particular, skin injuries are evolving as an epidemic issue. From a physiological standpoint, although wound repair takes place more rapidly in the skin than in other tissues, it is still a complex organ to reconstruct. Genetic and clinical variables, such as diabetes, smoking, and inflammatory/immunological pathologies, are also important risk factors limiting the regenerative potential of many therapeutic applications. Therefore, optimization of current clinical strategies is critical. Here, we summarize the current state of the field by focusing on stem cell therapy applications in wound healing, with an emphasis on current clinical approaches being developed. These involve protocols for the ex vivo expansion of adipose tissue-derived mesenchymal stem cells by means of a patented Good Manufacturing Practice-compliant platelet lysate. Combinations of multiple strategies, including genetic modifications and stem cells, biomimetic scaffolds, and novel vehicles, such as nanoparticles, are also discussed as future approaches.

Fat grafting for alleviating persistent pain after breast cancer treatment: A randomized controlled trial

BACKGROUND

Persistent pain is a common side effect of breast cancer treatment, affecting 24-52% of women after mastectomy. Recent studies have described analgesic effects of fat grafting in various settings. We aimed to investigate whether fat grafting had an analgesic effect on persistent pain after mastectomy and whether fat grafting had a remodeling effect on the mastectomy scar.

METHODS

This study was conducted as a randomized controlled trial. Patients were randomized to either receive fat grafting to the pain-afflicted area around the missing breast or a control group without any intervention. A total of 18 unilaterally mastectomized women with persistent pain ≥3 on the numerical rating scale were enrolled. Patients were examined at the baseline and at 3 and 6 months by using the DoloTest(®), visual analog scale (VAS) pain score, neuropathic pain symptom inventory, and patient and observer scar assessment scale.

RESULTS

A total of 15 patients were analyzed (fat grafted n = 8, control n = 7). The average amount of grafted fat was 71 ± 24.6 mL. Fat grafting showed a significant improvement in the pain as measured on the VAS pain scale (p = 0.001) with an average reduction of 54.9% and as measured on the neuropathic pain symptom inventory (p = 0.002). Furthermore, a significant improvement was observed in health-related quality of life (p = 0.007) and the quality of the scar (p < 0.001).

CONCLUSION

This is the first randomized controlled trial evaluating the analgesic effect of fat grafting. Fat grafting is a safe and effective technique for alleviating persistent pain after mastectomy.

An Overview of Fat Grafting

The use of autologous fat grafting for a wide variety of clinical applications has increased dramatically over the past few decades. The article provides an overview of the technique, a historic background, and briefly explores some of the current ways in which fat grafting is being used in plastic surgery.

A Comparison of Conventional Collagen Sponge and Collagen-Gelatin Sponge in Wound Healing

The objective of this study was to compare the effectiveness of the collagen-gelatin sponge (CGS) with that of the collagen sponge (CS) in dermis-like tissue regeneration. CGS, which achieves the sustained release of basic fibroblast growth factor (bFGF), is a promising material in wound healing. In the present study, we evaluated and compared CGSs and conventional CSs. We prepared 8 mm full-thickness skin defects on the backs of rats. Either CGSs or CSs were impregnated with normal saline solution (NSS) or 7 μg/cm(2) of bFGF solution and implanted into the defects. At 1 and 2 weeks after implantation, tissue specimens were obtained from the rats of each group (n = 3, total n = 24). The wound area, neoepithelial length, dermis-like tissue area, and the number and area of capillaries were evaluated at 1 and 2 weeks after implantation. There were no significant differences in the CGS without bFGF and CS groups. Significant improvements were observed in the neoepithelial length, the dermis-like tissue area, and the number of newly formed capillaries in the group of rats that received CGSs impregnated with bFGF. The effects on epithelialization, granulation, and vascularization of wound healing demonstrated that, as a scaffold, CGSs are equal or superior to conventional CSs.