Content of the Growth Factors bFGF, IGF-1, VEGF, and PDGF-BB in Freshly Harvested Lipoaspirate after Centrifugation and Incubation:

Cell-assisted lipotransfer in treating uncontrollable sepsis associated perianal fistula: a pilot study

PURPOSE

Surgeons can treat debilitating conditions of uncontrollable complex anorectal fistulas with sepsis, even after repeated fistula surgeries, for curative intention. Adipose-derived stem cells have shown good outcomes for refractory Crohn fistula. Unfortunately, cell therapy has some limitations, including high costs. We have therefore attempted immediate cell-assisted lipotransfer (CAL) in treating refractory complex anal fistulas and observed its outcomes.

METHODS

In a retrospective study, CAL, using a mixture of freshly extracted autologous stromal vascular fraction (SVF) and fat tissues, was used to treat 22 patients of refractory complex anal fistula from March 2018 to May 2021. Preoperative and postoperative assessments were performed with direct visual inspection, digital palpation, and endoanal ultrasonography. A fistula was considered completely healed if (1) the patient had no symptoms of discharge or inflammation; (2) there were no visible secondary openings of fistula tract inside and outside of the anorectal unit and even in the perineum; and (3) there was no primary opening in the anus. The endpoint of complete remission was wound healing without signs of inflammation 3 months after CAL treatment.

RESULTS

In a total of 22 patients who received CAL treatment, 19 patients showed complete remission, 1 patient showed partial improvement, and 2 patients showed no improvement. One of the 2 patients without improvement at primary endpoint showed complete remission 9 months after CAL. There were no significant adverse effects of the procedure.

CONCLUSION

We found that the immediately-collected CAL procedure for refractory complex anal fistula showed good outcomes without adverse side effects. It can be strongly recommended as an alternative surgical option for the treatment of complex anal fistula that is uncontrollable even after repeated surgical procedures. However, considering the unpredictable characteristics of SVF, long-term follow-up is necessary.

Sublesional fat grafting leads to a temporary improvement of wound healing in chronic leg ulcers: A prospective, randomised clinical trial

Chronic wounds remain a therapeutic and financial challenge for physicians and the health care systems. Innovative, inexpensive and effective treatment methods would be of immense value. The sublesional fat grafting could be such treatment, although effectiveness and safety have only been assessed in a few randomised clinical trials. The fat graft was obtained by liposuction, washed with the Coleman method and then injected sublesional and into the wound margins after surgical debridement. For the control group, saline solution was used instead of fat. The primary endpoint was to determine the wound size reduction in both groups. The wounds were measured preoperatively, intraoperatively and 3, 7, 21 and 60 days after the intervention. A p-value of <0.05 was considered significant. Furthermore, histology and microbiology of the wounds and pain were assessed. A temporary effect of the treatment was observed after 14 and 21 days. The wound size reduction was significantly larger in the intervention group, whereas after 60 days, no significant difference was detected between both groups. No adverse events could be reported and the pain level was almost equal in the control and intervention group. Sublesional fat grafting temporarily enhanced healing of chronic wounds. The procedure was safe and the pain level was low. Repeated interventions could lead to complete wound closure, which should be determined in future studies.

Strategies to Improve AFT Volume Retention After Fat Grafting

BACKGROUND

Autologous fat grafting has gained increasing popularity used in plastic surgery as a strategy to improve functional and aesthetic outcome. However, variable augmentation results have concerned surgeons in that volume loss of grafted fat reported fluctuates unsteadily.

AIM

An optimal technique that clinically maximizes the long-term survival rate of transplantation is in urgent need to be identified.

METHOD

The PubMed/MEDLINE database was queried to search for animal and human studies published through March of 2022 with search terms related to adipose grafting encompassing liposuction, adipose graft viability, processing technique, adipose-derived stem cell, SVF and others.

RESULTS

45 in vivo studies met inclusion criteria. The principal of ideal processing technique is effective purification of fat and protection of tissue viability, such as gauze rolling and washing-filtration devices. Cell-assisted lipotransfer including SVF, SVF-gel and ADSCs significantly promotes graft retention via differentiation potential and paracrine manner. ADSCs induce polarization of macrophages to regulate inflammatory response, mediate extracellular matrix remodeling and promote endothelial cell migration and sprouting, and differentiate into adipocytes to replace necrotic cells, providing powerful evidence for the benefits and efficacy of cell-assisted lipotransfer.

CONCLUSION

Based on the current evidence, the best strategy can not be decided. Cell-assisted lipotransfer has great potential for use in regenerative medicine. But so far mechanically prepared SVF-gel is conducive to clinical promotion. PRP as endogenous growth factor sustained-release material shows great feasibility.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effect of Hyperbaric Oxygen Therapy on the Survival Rate of Autologous Fat Transplantation

OBJECTIVE

To investigate whether hyperbaric oxygen therapy can improve the survival rate of fat transplantation and analyze the possible mechanisms.

METHODS

Ninety SD rats were randomly divided into 3 groups. All the rats were cut into pieces with about 5 mL of fat from the abdominal cavity, rinsed with normal saline for 3 times, and cleaned with cotton pad adsorption method. Then, 3 ml was removed, divided into 3 parts, and injected into three adjacent but not touching parts of the back. Group A received 1h/d hyperbaric oxygen therapy, group B received 2 h/d hyperbaric oxygen therapy, and group C received no hyperbaric oxygen therapy. The hyperbaric oxygen therapy lasted for 10 consecutive days. Fat grafts from one site were randomly removed at 2, 4, and 6 weeks after surgery, respectively. ① the survival rate of fat transplantation in three groups was compared. ② observe the pathological section; ③ immunohistochemistry was used to detect and compare the expression of vascular endothelial growth factor.

RESULTS

The survival rate of fat transplantation in group A was the highest. After subcutaneous transplantation of 1 ml of fat and 1 hour/day of continuous hyperbaric oxygen treatment for 10 days, the fat survival rates were 0.796 ± 0.071 ml, 0.644 ± 0.151 ml, and 0.473 ± 0.127 ml at the second, fourth, and sixth weeks, respectively. The survival rate of fat transplantation in group B was the second. After subcutaneous transplantation of 1 ml of fat and 2 hour/day of continuous hyperbaric oxygen treatment for 10 days, the survival rate of fat was 0.624 ± 0.220 ml, 0.494 ± 0.125 ml, and 0.329 ± 0.153 ml at the second, fourth, and sixth weeks, respectively. The survival rate of fat transplantation in group C was the lowest. After subcutaneous transplantation of 1 ml of fat and no hyperbaric oxygen treatment for 10 days, the fat survival rates were 0.461 ± 0.132 ml, 0.290 ± 0.112 ml and 0.169 ± 0.091 ml at the second, fourth, and sixth weeks, respectively. We have made changes in the abstract of the article and marked in red color.

CONCLUSION

Hyperbaric oxygen therapy is conducive to the survival of transplanted fat. Importantly, a short period of hyperbaric oxygen therapy (1 h/d) can promote the survival of transplanted fat.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Fat Juice: A Novel Approach on the Usage and Preparation of Adipose Tissue By-Products

BACKGROUND

Adipose tissue is considered to be naturally rich in a range of bioactive substances that may be extracted directly for therapeutic use without the need for cell isolation or culture.

OBJECTIVES

The aim of this study was to introduce a novel approach that utilizes stromal vascular fraction in conjunction with fat extract, termed "fat juice," and to perform a comprehensive biochemical analysis in relation to the potential clinical relevance of this new combination.

METHODS

A total of 11 samples of fat juice from the abdominal lipoaspirate were extracted from 11 healthy patients and analyzed in terms of the quantity and viability of stem cells, the presence and quantification of connective tissue fibers on histopathologic examination, and the levels of interleukin-6, mannose receptor C type 1, and vascular endothelial growth factor measured by enzyme-linked immunosorbent assay.

RESULTS

Total stem cell amounts ranged from 0.14 × 105 to 1.31 × 105, and cell viability rates varied between 20% and 67.9%. Interleukin-6 protein and vascular endothelial growth factor expressions were highest in Sample 3, while staining intensity was highest in Sample 4. For collagen I, collagen III, and elastin, the highest expressions were observed in Samples 4 and 8, in Sample 3, and in Samples 2 and 4, respectively.

CONCLUSIONS

Fat juice provides an easy-to-inject concentration of adipocyte/preadipocytes, red blood cells, adipose-derived stem cells, endothelial-derived cells, and cell residues. Prepared through an easy isolation process enabling abundant availability, fat juice seems to be an effective skin quality enhancer with potential for widespread use in the fields of plastic surgery, dermatology, and aesthetic/regenerative medicine.

The Effects of Shear Force-Based Processing of Lipoaspirates on White Adipose Tissue and the Differentiation Potential of Adipose Derived Stem Cells

Autologous lipotransfer is a promising method for tissue regeneration, because white adipose tissue contains a heterogeneous cell population, including mesenchymal stem cells, endothelial cells, immune cells, and adipocytes. In order to improve the outcome, adipose tissue can be processed before application. In this study, we investigated changes caused by mechanical processing. Lipoaspirates were processed using sedimentation, first-time centrifugation, shear-force homogenization, and second-time centrifugation. The average adipocyte size, stromal vascular cell count, and adipocyte depot size were examined histologically at every processing step. In addition, the adipose derived stem cells (ADSCs) were isolated and differentiated osteogenically and adipogenically. While homogenization causes a disruption of adipocyte depots, the shape of the remaining adipocytes is not changed. On average, these adipocytes are smaller than the depot adipocytes, they are surrounded by the ECM, and therefore mechanically more stable. The volume loss of adipocyte depots leads to a significant enrichment of stromal vascular cells such as ADSCs. However, the mechanical processing does not change the potential of the ADSCs to differentiate adipogenically or osteogenically. It thus appears that mechanically processed lipoaspirates are promising for the reparation of even mechanically stressed tissue as that found in nasolabial folds. The changes resulting from the processing correspond more to a filtration of mechanically less stable components than to a manipulation of the tissue.

In Vivo Evaluation of Mechanically Processed Stromal Vascular Fraction in a Chamber Vascularized by an Arteriovenous Shunt

Mechanically processed stromal vascular fraction (mSVF) is a promising source for regenerative purposes. To study the in vivo fate of the mSVF, we herein used a vascularized tissue engineering chamber that insulates the target mSVF from the surrounding environment. In contrast to previous models, we propose an arteriovenous (AV) shunt between saphenous vessels in rats without a venous graft. Mechanical SVF was processed from the fat pads of male Sprague Dawley rats, mixed with a fibrin hydrogel and implanted into an inguinal tissue engineering chamber. An arteriovenous shunt was established between saphenous artery and vein. On the contralateral side, an mSVF-fibrin hydrogel mix without vascular axis served as a non-vascularized control. After two and six weeks, rats were sacrificed for further analysis. Mechanical SVF showed significant numbers of mesenchymal stromal cells. Vascularized mSVF explants gained weight over time. Perilipin and CD31 expression were significantly higher in the mSVF explants after six weeks while no difference in DAPI positive cells, collagen deposition and FABP4 expression was observed. Morphologically, no differentiated adipocytes but a dense cell-rich tissue with perilipin-positive cells was found after six weeks. The phosphorylation of ERK1/2 was significantly enhanced after six weeks while Akt activation remained unaltered. Finally, mSVF explants stably expressed and released VEGF, bFGF and TGFb. Vascularized mSVF is able to proliferate and express adipocyte-specific markers. The AV shunt model is a valuable refinement of currently existing AV loop models in the rat which contributes to the fundamental 3R principles of animal research.

An Evaluation of the Effect of Activation Methods on the Release of Growth Factors from Platelet-Rich Plasma

BACKGROUND

Activation of platelets in platelet-rich plasma may improve growth factor release, thus enhancing regenerative properties. The authors investigated whether different methods of platelet-rich plasma activation affected growth factor release kinetics over time.

METHODS

Platelet-rich plasma from 20 healthy volunteers was processed by six different methods: (1) control (nonactivated); (2) activation with calcium chloride; (3) activation with calcium chloride and ethanol; (4) activation with calcium chloride and ethanol at 4°C; (5) activation with calcium chloride and ethanol with vitamin C; (6) activation with calcium chloride and ethanol with vitamin C at 4°C. Concentration of secreted vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and insulin-like growth factor over 24 hours was measured by immunoassay.

RESULTS

Calcium chloride-activated platelet-rich plasma produced significantly more insulin-like growth factor at 1 hour compared to cold and vitamin C platelet-rich plasma, and calcium chloride plus ethanol produced significantly more at 24 hours compared to vitamin C platelet-rich plasma. The addition of vitamin C reduced release of PDGF over time. Activation with calcium chloride and ethanol with or without cold temperature produced a gradual PDGF release as opposed to calcium chloride alone, which caused higher PDGF within 4 hours. There were no significant differences between groups for VEGF, although calcium chloride and cooled platelet-rich plasma approached significance for producing more than vitamin C platelet-rich plasma.

CONCLUSIONS

Activation of platelet-rich plasma does not significantly improve growth factor secretion, which is made worse by the addition of vitamin C, a platelet inhibitor. Ethanol does not negatively impact growth factor production and may offer a more gradual release.

CLINICAL RELEVANCE STATEMENT

These findings will help guide platelet-rich plasma preparation methods where therapeutic growth factors are used.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Adipokines in dental pulp: physiological, pathological, and potential therapeutic roles

BACKGROUND

Hundreds of adipokines have been identified, and their extensive range of endocrine functions-regulating distant organs such as oral tissues-and local autocrine/paracrine roles have been studied. In dentistry, however, adipokines are poorly known proteins in the dental pulp; few of them have been studied despite their large number. This study reviews recent advances in the investigation of dental-pulp adipokines, with an emphasis on their roles in inflammatory processes and their potential therapeutic applications.

HIGHLIGHTS

The most recently identified adipokines in dental pulp include leptin, adiponectin, resistin, ghrelin, oncostatin, chemerin, and visfatin. They have numerous physiological and pathological functions in the pulp tissue: they are closely related to pulp inflammatory mechanisms and actively participate in cell differentiation, mineralization, angiogenesis, and immune-system modulation.

CONCLUSION

Adipokines have potential clinical applications in regenerative endodontics and as biomarkers or targets for the pharmacological management of inflammatory and degenerative processes in dental pulp. A promising direction for the development of new therapies may be the use of agonists/antagonists to modulate the expression of the most studied adipokines.

The Role of Macrophage Migration Inhibitory Factor in Adipose-Derived Stem Cells Under Hypoxia

Background: Adipose-derived stem cells (ASCs) are multipotent mesenchymal stem cells characterized by their strong regenerative potential and low oxygen consumption. Macrophage migration inhibitory factor (MIF) is a multifunctional chemokine-like cytokine that is involved in tissue hypoxia. MIF is not only a major immunomodulator but also is highly expressed in adipose tissue such as subcutaneous adipose tissue of chronic non-healing wounds. In the present study, we investigated the effect of hypoxia on MIF in ASCs isolated from healthy versus inflamed adipose tissue. Methods: Human ASCs were harvested from 17 patients (11 healthy adipose tissue samples, six specimens from chronic non-healing wounds). ASCs were treated in a hypoxia chamber at <1% oxygen. ASC viability, MIF secretion as well as expression levels of MIF, its receptor CD74, hypoxia-inducible transcription factor-1α (HIF-1α) and activation of the AKT and ERK signaling pathways were analyzed. The effect of recombinant MIF on the viability of ASCs was determined. Finally, the effect of MIF on the viability and production capacity of ASCs to produce the inflammatory cytokines tumor necrosis factor (TNF), interleukin (IL)-6, and IL-1β was determined upon treatment with recombinant MIF and/or a blocking MIF antibody. Results: Hypoxic treatment inhibited proliferation of ASCs derived from healthy or chronic non-healing wounds. ASCs from healthy adipose tissue samples were characterized by a low degree of MIF secretion during hypoxic challenge. In contrast, in ASCs from adipose tissue samples of chronic non-healing wounds, secretion and expression of MIF and CD74 expression were significantly elevated under hypoxia. This was accompanied by enhanced ERK signaling, while AKT signaling was not altered. Recombinant MIF did stimulate HIF-1α expression under hypoxia as well as AKT and ERK phosphorylation, while no effect on ASC viability was observed. Recombinant MIF significantly reduced the secretion of IL-1β under hypoxia and normoxia, and neutralizing MIF-antibodies diminished TNF-α and IL-1β release in hypoxic ASCs. Conclusions: Collectively, MIF did not affect the viability of ASCs from neither healthy donor site nor chronic wounds. Our results, however, suggest that MIF has an impact on the wound environment by modulating inflammatory factors such as IL-1β.

Regenerative Strategy for Persistent Periprosthetic Leakage around Tracheoesophageal Puncture: Is It an Effective Long-Term Solution?

Autologous tissue-assisted regenerative procedures have been considered effective to close different types of fistula, including the leakage around tracheoesophageal puncture. The aim of this study was to retrospectively review 10 years of lipotransfer for persistent periprosthetic leakage in laryngectomized patients with voice prosthesis. Clinical records of patients who experienced periprosthetic leakage from December 2009 to December 2019 were reviewed. Patients receiving fat grafting were included. The leakage around the prosthesis was assessed with a methylene blue test. Twenty patients experiencing tracheoesophageal fistula enlargement were treated with fat grafting. At the one-month follow-up, all patients were considered improved with no leakage observed. At six months, a single injection was sufficient to solve 75% of cases (n 15), whereas 25% (n 5) required a second procedure. The overall success rate was 80% (n 16). Results remained stable for a follow-up of 5.54 ± 3.97 years. Fat grafting performed around the voice prosthesis, thanks to its volumetric and regenerative properties, is a valid and lasting option to solve persistent periprosthetic leakage.

Standardization and characterization of adipose-derived stromal vascular fraction from New Zealand white rabbits for bone tissue engineering

Background and Aim:

Adipose tissue-derived stromal vascular fraction (SVF) contains a heterogeneous cell population comprising multipotent adipose-derived stem cells. Regenerative therapy using adipose-derived SVF has broad applications in bone tissue engineering due to the superior osteogenic potential of SVF. This study was designed to standardize and characterize adipose-derived SVF obtained from New Zealand white rabbits for bone tissue engineering and other potential applications.

Materials and Methods:

Ten skeletally mature and clinically healthy adult New Zealand white rabbits were used in this study. The SVF was prepared using surgically resected interscapular adipose tissue following enzymatic digestion with 0.1% collagenase type I solution. The SVF pellet obtained after the final centrifugation step was suspended in a 0.5 mL control solution to obtain ready-to-use adipose-derived SVF. The freshly prepared SVF was characterized based on the total SVF cell count and cell yield per gram of adipose tissue. The SVF cells were enumerated using a hemocytometer.

Results:

Interscapular adipose tissue depots are ideal for preparing autologous adipose-derived SVF due to the ease of access. The interscapular adipose-derived SVF prepared by enzymatic digestion had an average cell yield of 3.15±0.09×10⁶ cells/g adipose tissue. Freshly prepared SVF had a total cell count of 3.15±0.09×10⁴ cells/μL.

Conclusion:

The enzymatic digestion of adipose tissue using 0.1% collagenase resulted in better cell yield per gram than methods previously reported in rabbits. The use of adipose-derived SVF can preclude the requirement for an additional culture period. In addition, it may also reduce the risk of extensive cell contamination, which makes it a safe and cost-effective strategy for bone tissue engineering applications.

Physical, Biochemical, and Biologic Properties of Fat Graft Processed via Different Methods

Clinical use of autologous fat for correction of soft-tissue defects in cosmetic and reconstructive procedures has grown in popularity. Graft processing is implicated as one of the variable factors affecting quality, viability, and subsequent graft survival. This study analyzed the in vitro physical and biologic characteristics of lipoaspirate processed using different techniques.

Methods

Fresh lipoaspirates from patients with informed consent were processed by 4 methods: decantation, centrifugation, the REVOLVE System, and PureGraft. Processed fat grafts were analyzed for yield, composition, tissue particle size and morphology, and viability and function of adipocytes and stem cells. Fat tissue harvested from waste containers of REVOLVE and PureGraft and trapped on REVOLVE paddles was also evaluated.

Results

Grafts produced by the filtration systems contained the highest percentage of fat tissue, whereas those from decantation contained the lowest percentage, although they have the highest volume yield. In addition, grafts from REVOLVE and PureGraft showed more large-sized particles (>1000 μm) than those from decantation or centrifugation. REVOLVE also preserved significantly higher populations of viable and functional adipocytes and stromal vascular fraction cells when compared with other processing methods. Tissue particles in waste containers of REVOLVE and PureGraft were mostly (>85%) <300 μm and demonstrated a minimal number of viable adipocytes and stem cells. Fat tissues trapped on REVOLVE paddles contained a higher percentage of noninjectable and fibrous collagen bundles.

Conclusion

Different processing methods result in fat grafts with varying physical and biologic properties, which may contribute to fat graft viability and retention in vivo.

The Importance of Breast Adipose Tissue in Breast Cancer

Adipose tissue is a complex endocrine organ, with a role in obesity and cancer. Adipose tissue is generally linked to excessive body fat, and it is well known that the female breast is rich in adipose tissue. Hence, one can wonder: what is the role of adipose tissue in the breast and why is it required? Adipose tissue as an organ consists of adipocytes, an extracellular matrix (ECM) and immune cells, with a significant role in the dynamics of breast changes throughout the life span of a female breast from puberty, pregnancy, lactation and involution. In this review, we will discuss the importance of breast adipose tissue in breast development and its involvement in breast changes happening during pregnancy, lactation and involution. We will focus on understanding the biology of breast adipose tissue, with an overview on its involvement in the various steps of breast cancer development and progression. The interaction between the breast adipose tissue surrounding cancer cells and vice-versa modifies the tumor microenvironment in favor of cancer. Understanding this mutual interaction and the role of breast adipose tissue in the tumor microenvironment could potentially raise the possibility of overcoming breast adipose tissue mediated resistance to therapies and finding novel candidates to target breast cancer.

Fat graft for reducing pain in chronic wounds

BACKGROUND

Chronic wounds are one of the most important challenge for regenerative surgery. Plastic surgeon can use fat graft to increase wound healing because its growth factors can enhance tissue regeneration. In a recent study, the authors evaluated a reduction of pain in a cohort of patients submitted to breast reconstruction with breast implant and lipofilling, putting into evidence that growth factors in fat graft can reduce post-surgical pain. The aim of this work is to evaluate ultra-filtered fat graft potential in reducing pain in chronic wounds.

PATIENTS AND METHODS

Fifty new patients with chronic wounds of different etiology were recruited for this study and divided into two groups: A, treatment and B, control. Twenty-five patients per group. Negative pressure therapy dressing was applied after surgical debridement. Three days later patients in group A received ultrafiltered fat graft. Pain was evaluated with preoperative Visual Analogic Scale, repeated twice a day for 14 days and finally 21 days from procedures.

RESULTS

In group A (treated patients), pain was lower. These data were confirmed even after 7 days. The overall statistical analysis of the average of all values (SD 1.72) confirmed that the differences were significant at the 95% with the Chi-square test and analysis of variance (P value < .05).

CONCLUSIONS

The ultra-filtered fat graft placed on the wound bed and edges was effective in reducing pain in chronic wounds. The reduction of pain was statistically significant.

How Fat Grafting Works

Fat grafting has been shown to improve diseased soft issue. Although the mechanism behind fat grafting’s regenerative properties is currently debated, published studies agree that there is an associated vasculogenic effect. A systematic literature review was conducted to elucidate the biochemical pathways responsible for establishing neo-vasculature to grafted fat.

Impact of growth factor content on proliferation of mesenchymal stromal cells derived from adipose tissue

Autologous adipose tissue (AT) transfer has gained widespread acceptance and is used for a broad variety of regenerative clinical indications. It is assumed that the successful outcome of AT transfer essentially depends on the amount of autocrine-generated growth factors (GF). It is supposed that several GF enhance and improve the anatomic and functional integration of the transplanted AT grafts at the site of implantation. In the present study we have investigated for the first time the correlation between the concentration of GF of freshly isolated AT and the proliferation and migration capacity of mesenchymal stroma cells (MSCs) derived from the respective AT sample. We here show that the proliferation and migration capacity of MSCs strongly depends on the GF content of the AT the cells were isolated from but in an inversely proportional manner. The lower the GF content of an AT sample was, the higher was the proliferation and migration capacity of the respective MSC population contained in the AT and vice versa. Furthermore, we found that supplementation with recombinant GFs only in the case of AT samples with low but not with higher growth factor contents led to a significant enhancement of proliferation and migration of the AT-resident MSCs. As we further show, this inefficiency of GFs to enhance MSC proliferation and migration in AT samples with high GF contents indicates a GF-mediated negative feedback mechanism leading to an impaired GF signaling in MSC obtained from those AT samples. Our results might explain why the successful use of AT grafting is frequently limited by low and unpredictable survival rates, and we suggest to use the knowledge of GF content of harvested AT as a predictive clinical parameter for risk assessment of the therapeutic outcome of autologous AT transfer.

Human Adipose Tissue Derivatives as a Potent Native Biomaterial for Tissue Regenerative Therapies

BACKGROUND

Human adipose tissue is a great source of translatable biomaterials owing to its ease of availability and simple processing. Reusing discardable adipose tissue for tissue regeneration helps in mimicking the exact native microenvironment of tissue. Over the past 10 years, extraction, processing, tuning and fabrication of adipose tissue have grabbed the attention owing to their native therapeutic and regenerative potential. The present work gives the overview of next generation biomaterials derived from human adipose tissue and their development with clinical relevance.

METHODS

Around 300 articles have been reviewed to widen the knowledge on the isolation, characterization techniques and medical applications of human adipose tissue and its derivatives from bench to bedside. The prospective applications of adipose tissue derivatives like autologous fat graft, stromal vascular fraction, stem cells, preadipocyte, adipokines and extracellular matrix, their behavioural mechanism, rational property of providing native bioenvironment, circumventing their translational abilities, recent advances in featuring them clinically have been reviewed extensively to reveal the dormant side of human adipose tissue.

RESULTS

Basic understanding about the molecular and structural aspect of human adipose tissue is necessary to employ it constructively. This review has nailed the productive usage of human adipose tissue, in a stepwise manner from exploring the methods of extracting derivatives, concerns during processing and its formulations to turning them into functional biomaterials. Their performance as functional biomaterials for skin regeneration, wound healing, soft tissue defects, stem cell and other regenerative therapies under in vitro and in vivo conditions emphasizes the translational efficiency of adipose tissue derivatives.

CONCLUSION

In the recent years, research interest has inclination towards constructive tissue engineering and regenerative therapies. Unravelling the maximum utilization of human adipose tissue derivatives paves a way for improving existing tissue regeneration and cellular based therapies and other biomedical applications.

Fat Therapeutics: The Clinical Capacity of Adipose-Derived Stem Cells and Exosomes for Human Disease and Tissue Regeneration

Fat grafting is a well-established surgical technique used in plastic surgery to restore deficient tissue, and more recently, for its putative regenerative properties. Despite more frequent use of fat grafting, however, a scientific understanding of the mechanisms underlying either survival or remedial benefits of grafted fat remain lacking. Clinical use of fat grafts for breast reconstruction in tissues damaged by radiotherapy first provided clues regarding the clinical potential of stem cells to drive tissue regeneration. Healthy fat introduced into irradiated tissues appeared to reverse radiation injury (fibrosis, scarring, contracture and pain) clinically; a phenomenon since validated in several animal studies. In the quest to explain and enhance these therapeutic effects, adipose-derived stem cells (ADSCs) were suggested as playing a key role and techniques to enrich ADSCs in fat, in turn, followed. Stem cells - the body's rapid response 'road repair crew' - are on standby to combat tissue insults. ADSCs may exert influences either by releasing paracrine-signalling factors alone or as cell-free extracellular vesicles (EVs, exosomes). Alternatively, ADSCs may augment vital immune/inflammatory processes; or themselves differentiate into mature adipose cells to provide the 'building-blocks' for engineered tissue. Regardless, adipose tissue constitutes an ideal source for mesenchymal stem cells for therapeutic application, due to ease of harvest and processing; and a relative abundance of adipose tissue in most patients. Here, we review the clinical applications of fat grafting, ADSC-enhanced fat graft, fat stem cell therapy; and the latest evolution of EVs and nanoparticles in healing, cancer and neurodegenerative and multiorgan disease.

Fat Grafting for Facial Rejuvenation: My Preferred Approach

The author provides his preferred approach to fat grafting for facial rejuvenation. The preferred donor sites include low abdomen and inner thigh. Fat grafts should be harvested with low negative pressure to ensure the integrity and viability of adipocytes. Fat grafts can be processed with proper centrifugation that can reliably produce purified fat with concentrated growth factors and adipose-derived stem cells, all of which are beneficial to improve graft survival. The approach described in this article is supported by the most scientific studies and thus may provide a more predictable long-lasting result if performed properly.

Microfat and Lipoconcentrate for the Treatment of Facial Scars

Fat grafting is as a unique regenerative filler with soluble factors and progenitor cells that may remodel scar tissue in an easy yet effective way. A combination of microfat grafting, lipococoncentrate injection, scar subcision, and platelet-rich plasma supplementation may be used to treat the majority of facial scars. The lipoconcentrate technique condenses the lipoaspirate to a progenitor cell-rich fluid of low volume by a combination of centrifugation and emulsification steps. In this article, the authors' methods for scar treatment by fat grafting are discussed. Choice of technique for facial scars, precise indications, and contraindications are introduced.

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.

Injectable Tissue Replacement and Regeneration: Anatomic Fat Grafting to Restore Decayed Facial Tissues

Aging is a dynamic process that can be modeled and understood tissue by tissue and cell by cell. Numerous authors have helped us understand the anatomy of facial fat compartments and the effects of aging on our facial tissues such as skin, fat, bone and fibrous ligaments. Injectable tissue replacement and regeneration (ITR2) is a method to replace decayed tissues of the face using “like tissues” in an effort to delay or slow the rate of tissue decay seen in facial aging. Facial topography and proportion analysis are performed to diagnose individual-specific losses of facial fat. The degree of sun damage and skin thinning is noted as is the degree of loss in the superficial fat compartment. Deep compartment fat loss is evaluated as is pyriform aperture, orbital, mandibular ramus, mandibular body, and chin resorption. From this analysis, a detailed treatment plan is formulated. Using a mechanical device, 3 different fat grafts are created: 2 mm (millifat), 1 mm (microfat), and 500 microns (cell optimized, matrix rich nanofat); anatomic replacement of all areas of tissue loss is carried out. Millifat is used for deep compartment and bone losses, microfat for superficial fat losses above the facial musculature and nanofat is used intradermally and as a biological cream for topical application. The rationale behind this standardized approach is explained and the scientific foundations for the idea are presented. Reduction in tissue decay appears to be a valid observation, but awaits others confirmation.

Adipokine concentrations in lipoaspirates may have a role in wound healing

OBJECTIVES

In addition to its use as a volume filler, fat grafting may have a potential role in wound healing based on the concentration of growth factors in the lipoaspirate. In this study, we compare the quantitative and qualitative concentration of the various growth factors and adipokines using the Shippert or the Coleman techniques to prepare the lipoaspirate.

METHODS

We measured leptin, adiponectin and the growth factors, i.e., acidic fibroblast growth factor (aFGF), basic FGF (bFGF), keratinocyte growth factor (KGF), bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) by ELISA in solid and liquid fractions obtained with both techniques in human fat obtained with Coleman technique and Shippert technique.

RESULTS

All of these peptides, except BMP-2, were detected in relevant quantities in the solid fraction. The Coleman but not the Shippert technique resulted in statistically higher adiponectin concentrations in the solid tissue fraction. The other four growth factors occurred in significantly higher concentrations in the solid fractions compared to the liquid fractions, independent of the processing technique.

CONCLUSION

In summary, we demonstrated that KGF, aFGF, bFGF and VEGF, as well as leptin and adiponectin, are contained in fat suspensions obtained by liposuction and in the supernatant. Only the concentration of adiponectin was in the range reported to contribute to wound healing.

[Research progress in adipose tissue promoted wound healing]

Objective

To summarize recent progress in adipose tissue acting as a more efficient and ideal therapy to facilitate wound repair and evaluate the therapeutic values of adipose tissue.

Methods

The related literature about adipose tissue for wound healing in recent years was reviewed and analyzed.

Results

Enormous studies focus on the capacity of adipose tissue to accelerate wound healing including cellular components, extracellular matrix, and paracrine signaling have been investigated.

Conclusion

Adipose tissue has generated great interest in recent years because of unique advantages such as abundant and accessible source, thriven potential to enhance the regeneration and repair of damaged tissue. However, there is still a need to explore the mechanism that adipose tissue regulates cellular function and tissue regeneration in order to facilitate clinical application of adipose tissue in wound healing.

Concentration of Chondrogenic Soluble Factors in Freshly Harvested Lipoaspirate

BACKGROUND

Cartilage tissue has a limited capacity for healing with the consequence that patients are often treated symptomatically until they become candidates for osteotomy or total joint replacement. Alternative biological therapies, for example, application of platelet-rich plasma and implantation of chondrocytes and mesenchymal stem cells, have emerged as a new treatment modality to repair articular cartilage. In addition, autologous fat transfer is performed for treatment of cartilage defects, example given, in osteoarthrosis, but several questions regarding basic biochemical properties of the transplant remain unanswered. Bone morphogenetic protein 4 (BMP4), matrix metalloproteinase (MMP)-8, cartilage oligomeric matrix protein (COMP), and chitinase-3-like protein 1 (CHI3L1) have been shown to be involved in chondrogenic regeneration and represent potential therapeutic agents for cartilage repair. However, no study regarding naturally occurring levels of these soluble factors in transplanted adipose tissue has yet been performed.

METHODS

To investigate the influence of age, body mass index, donor site, and sex on the concentration of BMP4, MMP-8, COMP, and CHI3L1 in freshly aspirated adipose tissue, their content was measured by means of enzyme-linked immunosorbent assay readings.

RESULTS

There were significant quantities of BMP4, MMP-8, COMP, and CHI3L1 (23.6, 249.9, 298.0, and 540.6 pg/mg, respectively) in the lipoaspirate harvested for transplantation. There was no correlation between the content of soluble factors and the patients' age or body mass index. Furthermore, the sex did not affect the amount of the investigated factors. However, there were significantly lower contents of BMP4, COMP, and CHI3L1 found in lipoaspirates harvested from the abdomen compared with nonabdominal donor sites.

CONCLUSIONS

Naturally occurring differences in the concentrations of the investigated soluble factors will favor certain donor sites for autologous fat transfer in the field of cartilage repair. Thus, increasing knowledge will enable researchers and clinicians to make autologous fat transfer procedures more reliable and efficient for treatment of articular cartilage defects.

Increased Angiogenic and Adipogenic Differentiation Potentials in Adipose-Derived Stromal Cells from Thigh Subcutaneous Adipose Depots Compared with Cells from the Abdomen

BACKGROUND

Adipose-derived stromal cells (ADSCs) may play a pivotal role by differentiating into multilineage cells or by secreting growth factors or cytokines in cell-assisted lipotransfer, which participates in adipose tissue regeneration. The angiogenic potential of various ADSCs from different anatomical regions remains uncertain.

OBJECTIVES

The authors sought to offer appropriate choices of sources of adipose-derived stromal cells for cell-assisted lipotransfer and tissue engineering.

METHODS

ADSCs were harvested from subcutaneous adipose depots in the abdomen and thighs. The expression of adipocyte-specific markers was evaluated, and Oil Red O staining was performed to assess the capacity for adipogenic differentiation. Angiogenic differentiation potential was evaluated by detecting the expression of vascular endothelial growth factor, vascular endothelial growth factor 2, and CD31. A tube formation assay was also performed to analyze the angiogenic differentiation capacity.

RESULTS

ADSCs from the thigh showed more significant angiogenic and adipogenic potential. More lipogenesis was identified in ADSCs from the thigh, and this was accompanied by the enhancement of adipocyte markers. Angiogenesis was more vigorous in the thigh-derived stromal cells, and ADSCs from the thigh depot showed more junctions and longer tubule formation on Matrigel in vitro.

CONCLUSIONS

Thigh-derived ADSCs exhibited greater capacity for adipogenic and angiogenic differentiation and would be a better option for cell-assisted lipotransfer and tissue engineering.

Unfiltered Nanofat Injections Rejuvenate Postburn Scars of Face

The aim of this study was to compare the quality of postburn facial scars before and after injection of unfiltered nanofat. The study was performed in the Plastic Surgery Department of Mayo Hospital, Lahore, Pakistan, from January 2015 to December 2016. Forty-eight patients with postburn facial scars were included; age range was 4 to 32 years with Fitzpatrick skin types between 3 and 4. Patients with hypertrophic scars, contractures, or keloids were excluded. Scars were assessed by a senior plastic surgeon and the patient on the POSAS (Patient Observer Scar Assessment Scale). Fat was harvested from the abdomen and/or thighs with a 3-mm multiport liposuction cannula (containing several sharp side holes of 1 mm) using Coleman technique. The harvested fat was emulsified and transferred into 1-mL Luer-Lock syringes for injection into the subdermal or intradermal plane. Final follow-up was scheduled at 6 months, and scar was rated by the patient and the same surgeon on the POSAS. Preoperative and postoperative scar scores were compared, and P values were calculated. Results indicated that after nanofat grafting, there was a statistically significant improvement in scar quality. The most significant improvements on the observer scale were seen in pigmentation and pliability (P < 0.0001). Thickness and relief were the least improved variables (P = of 0.785 and 0.99, respectively). ImageJ scanning also showed pigmentation change (P = 0.076). A statistically significant improvement was seen in all parameters of the patient section of the POSAS (P < 0.0001). In conclusion, unfiltered nanofat grafting seems to be a promising and effective therapeutic approach in postburn facial scars, showing significant improvement in scar quality. The trial was registered on www.clinicaltrials.gov with following ID NCT03352297.

Enhancement of Progenitor Cells by Two-Step Centrifugation of Emulsified Lipoaspirates

BACKGROUND

Adipose-derived stem cells, endothelial progenitor cells, and soluble factors jointly contribute to the regenerative effect of fat grafts. Nanofat grafting emulsifies the lipoaspirate and increases the progenitor cell yield. In the present study, the authors evaluated their extended nanofat grafting method that includes two additional centrifugation steps and results in a lipoaspirate of low volume that they termed "lipoconcentrate." Furthermore, the authors investigated the oily fractions after centrifugation for their regenerative potential.

METHODS

Lipoaspirates of 20 healthy patients were processed by emulsification and/or centrifugation. Six groups were created: native (not emulsified) fat, 1× centrifuged native fat, 2× centrifuged native fat, nanofat (emulsified), 1× centrifuged nanofat, and lipoconcentrate (i.e., 2× centrifuged nanofat). The oily phases after the centrifugation steps were collected. Progenitor cells and basic fibroblast growth factor, insulin-like growth factor 1, matrix metalloproteinase-9, platelet-derived growth factor-BB, and vascular endothelial growth factor-A levels were measured by flow cytometry and immunoassays.

RESULTS

Lipoconcentrate contained significantly higher numbers of adipose-derived stem cells and endothelial progenitor cells per gram compared with all other fractions. No difference of all five soluble factors between groups was found. The oily phases after centrifugation showed no or very few adipose-derived stem cells and endothelial progenitor cells, and no or very low levels of soluble factors.

CONCLUSIONS

Centrifugation of emulsified lipoaspirates increases the progenitor cell count in the lipoaspirate. The oily phase after centrifugation of lipoaspirates may be disposable because of the minuscule content of progenitor cells and soluble factors.

The use of fat grafting and platelet-rich plasma for wound healing: A review of the current evidence

Fat grafting is becoming a common procedure in regenerative medicine because of its high content of growth factors and adipose derived stem cells (ADSCs) and the ease of harvest, safety, and low cost. The high concentration of ADSCs found in fat has the potential to differentiate into a wide range of wound-healing cells including fibroblasts and keratinocytes as well as demonstrating proangiogenic qualities. This suggests that fat could play an important role in wound healing. However retention rates of fat grafts are highly variable due in part to inconsistent vascularisation of the transplanted fat. Furthermore, conditions such as diabetes, which have a high prevalence of chronic wounds, reduce the potency and regenerative potential of ADSCs. Platelet-rich plasma (PRP) is an autologous blood product rich in growth factors, cell adhesion molecules, and cytokines. It has been hypothesised that PRP may have a positive effect on the survival and retention of fat grafts because of improved proliferation and differentiations of ADSCs, reduced inflammation, and improved vascularisation. There is also increasing interest in a possible synergistic effect that PRP may have on the healing potential of fat, although the evidence for this is very limited. In this review, we evaluate the evidence in both in vitro and animal studies on the mechanistic relationship between fat and PRP and how this translates to a benefit in wound healing. We also discuss future directions for both research and clinical practice on how to enhance the regenerative potential of the combination of PRP and fat.

Fat extract promotes angiogenesis in a murine model of limb ischemia: a novel cell-free therapeutic strategy

Background

The proangiogenic capacity of adipose tissue and its derivatives has been demonstrated in a variety of studies. The paracrine mechanism of the cellular component is considered to play a critical role in the regenerative properties of these tissues. However, cell-based therapy for clinical application has been hindered by limitations such as safety, immunogenicity issues, and difficulties in cell preservation, transportation, and phenotype control. In the current study, we aimed to produce a cell-free extract directly from human fat tissue and evaluate its potential therapeutic efficacy.

Methods

We developed a novel physical approach to produce a cell-free aqueous extract from human fat tissue (fat extract (FE)). The therapeutic potential of FE was investigated in the ischemic hindlimb model of nude mice. After establishment of hindlimb ischemia with ligation of the left femoral artery and intramuscular injection of FE, blood perfusion was monitored at days 0, 7, 14, 21, and 28. Tissue necrosis and capillary density were evaluated. Enzyme-linked immunosorbent assay was used to analyze the growth factors contained in FE. Moreover, the proliferation, migration, and tube formation ability were tested on human umbilical vein endothelial cells (HUVECs) in vitro when treated with FE. The proangiogenic ability of FE was further assessed in an in-vivo Matrigel plug assay.

Results

FE was prepared and characterized. The intramuscular injection of FE into the ischemic hindlimb of mice attenuated severe limb loss and increased blood flow and capillary density of the ischemic tissue. Enzyme-linked immunosorbent assay showed that FE contained high levels of various growth factors. When added as a cell culture supplement, FE promoted HUVEC proliferation, migration, and tube formation ability in a dose-dependent manner. The subcutaneous injection of Matrigel infused with FE enhanced vascular formation.

Conclusions

We developed a novel cell-free therapeutic agent, FE, produced from human adipose tissue. FE was able to attenuate ischemic injury and stimulate angiogenesis in ischemic tissues. This study indicates that FE may represent a novel cell-free therapeutic agent in the treatment of ischemic disorders.

Percutaneous Autologous Fat Injection Following 2-Layer Flap Lower Blepharoplasty for the Correction of Tear Trough Deformity

Tear trough deformity has been an area that has received much attention in terms of esthetic improvements. Fat transposition has been commonly used for the treatment of tear trough deformity. As some patients have had minimal improvement by that method, we propose the use of fat grafting combined with open blepharoplasty to complement the sunken area, including some of anterior maxilla region, and evaluate and precisely remove the excessive tissue.Lower blepharoplasty was performed by separating the skin and muscle flap. The excessive or laxed tissue was evaluated during the procedure and resected in each flap. Fat grafting was performed after completing a lower blepharoplasty, to ensure accurate placement on the spot where the surgeon originally intended. Overcorrection is not recommended.No serious complications were reported during a period of 10 years. Only 4 patients required a secondary fat injection.Patients who require structural correction of the lower eyelid area (eg, aggressive herniated fat, excessive skin laxity, or bulky orbicularis oculi muscle) and who need complementary material to fill the lower lid area (eg, deep, wide sunken area or relative exophthalmos) are good candidates for blepharoplasty with a fat grafting procedure.

From the "Fat Capsule" to the "Fat Belt": Limiting Protective Lipofilling on Irradiated Expanders for Breast Reconstruction to Selective Key Areas

BACKGROUND

The number of patients undergoing mastectomy and immediate breast reconstruction with tissue expanders followed by post-mastectomy radiotherapy (PMRT) is exponentially increasing. To reduce the rate of complications, in 2011, the senior author of this manuscript described the use of protective lipofilling in patients undergoing unplanned PMRT to the expander with a specific protocol aiming to decrease the rate of complications.

OBJECTIVES

A study was performed to evaluate the thickness of the breast irradiated tissue to create a standard pattern of "protective" lipofilling infiltration on limited key areas that could re-establish a thickness similar to non-radiotreated tissues.

METHODS

We studied 15 patients who had modified radical mastectomy (MRM) with immediate breast reconstruction with tissue expanders and PMRT (Group 1) before expansion (Time1), before PMRT (Time2), after PMRT (Time3), 3 months after "protective" lipofilling (Time4), and 6 months after "protective" lipofilling (Time5). As a control group, we studied 15 patients who had MRM and immediate breast reconstruction with tissue expanders that would not undergo PMRT (Group 2) at the same time points of GROUP 1 (Time1,2,3). Tissue thickness was studied in specific areas using ultrasounds (US) and magnetic resonance imaging (MRI).

RESULTS

US and MRI measurements obtained 6 weeks after PMRT and 3 months after lipofilling showed an initial decrease and then an average increase in tissue thickness reaching values even higher than the non-radiotreated control group.

CONCLUSIONS

This preliminary report shows how a one-step "fat belt" surgical pattern of lipofilling delivered to central "selected" areas of the breast can achieve adequate tissue thickness in patients who underwent breast reconstruction with PMRT reaching a thickness similar (and in most cases higher) to non-radiotreated tissues. Further follow-up studies are needed to analyze long-term complications of tissue thinning such as ulceration and implant exposure, in comparison with the "fat capsule" pattern.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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.

A Systematic Review of Autologous Platelet-Rich Plasma and Fat Graft Preparation Methods

BACKGROUND

The addition of platelet-rich plasma (PRP) to adipose tissue may improve fat graft survival, although graft retention rates vary markedly between studies. To what extent this outcome heterogeneity reflects differing methodological factors remains unknown. This systematic review aims to synthesize and critically review methodological approaches to autologous PRP and fat cotransplantation in both human and animal studies.

METHODS

In accordance with PRISMA guidelines, Ovid MEDLINE, Scopus, and Cochrane Library databases were searched from inception to April 2017. Data were extracted from all in vivo studies involving autologous PRP and fat cotransplantation. A secondary aim was to assess reporting of technical detail; authors were not contacted to provide missing data.

RESULTS

From 335 articles, 23 studies were included in the qualitative synthesis. Some 21 were performed in humans and 2 in rabbits. Six studies were randomized control trials; the remainder reported on observational data. Methods of PRP extraction and activation varied markedly between studies. Fat graft preparation was comparatively more consistent. Methods of PRP and fat mixing differed significantly, especially with regards to relative volume/volume ratios.

CONCLUSIONS

Our study represents the first systematic review of methodological factors in autologous PRP and fat cotransplantation. It demonstrates that technical factors in graft preparation and administration vary significantly between in vivo studies. Such methodological heterogeneity may explain observed differences in experimental and clinical outcomes. Reporting of key procedural information is inconsistent and often inadequate. These issues make meaningful evaluation of the PRP-enhanced fat grafting literature difficult and may limit its translation into clinical practice.

Fat grafting for resurfacing an exposed implant in lower extremity: A case report

RATIONALE

Although numerous reconstruction protocols have been reported for lower leg trauma, those for distal leg trauma remain few. We present the case of a woman with an implant exposure wound, who was successfully treated through fat grafting, without major flap surgery.

PATIENT CONCERNS

An 83-year-old woman with an exposed implant in lower extremity received reconstruction surgery once and the surgery failed. She refused additional major surgery and negative pressure wound therapy.

DIAGNOSES

The diagnosis of a tibia and fibula shaft open fracture (type IIIA) complicated with an exposed implant was made.

INTERVENTIONS

The procedure was performed by deploying purified and emulsified fat with a Micro-Autologous Fat Transplantation gun. The required lipoaspirate amount was grossly estimated using a standard formula: 0.5 cc of a lipoaspirate per square centimeter of wound. We prepared the lipoaspirate simply through centrifugation followed by physical emulsification. The endpoint of fat grafting was when lipoaspirate began to flow out of the wound. The initial dressing after the procedure included the topical usage of biomycin ointment with AQUACEL Foam (ConvaTec Inc., NC, USA) coverage, which was later changed to INTRASITE gel (Smith & Nephew, London, UK) with a gauze dressing for 4 weeks. After 4 weeks, dressing components were changed to Mepilex (Mölnlycke Health Care, Gothenburg, Sweden) alone.

OUTCOMES

The wound healed completely without requiring major flap surgery by 18 weeks after surgery.

LESSONS

Fat grafting is one kind of cell therapy and potentially has regenerative effects during wound healing. Fat grafting is critical in the healing processes of complicated wounds and might be considered a step in reconstruction surgery.

Structural Fat Grafting to Improve Outcomes of Vocal Folds’ Fat Augmentation: Long-term Results

Objective

Evaluating the long-term outcomes of vocal fold structural fat grafting.

Study Design

Case series with chart review.

Setting

University hospital.

Subjects and Methods

Seventy-nine dysphonic patients (16-82 years; 55 with unilateral laryngeal paralysis and 24 with vocal fold scarring) underwent vocal fold fat injection. Fat was harvested by low-pressure liposuction and then processed by centrifugation. Refined fat aliquots were placed in the vocal fold and paraglottic space in multiple tunnels to enhance graft neovascularization. All patients were followed for 12 months, 15 for 3 years, and 5 for 10 years with videolaryngostroboscopy, maximal phonation time (MPT) measurement, Voice Handicap Index (VHI) questionnaire, and GRBAS (grade, roughness, breathiness, asthenia, strain) perceptual evaluation. Laryngeal computed tomography (CT) and/or magnetic resonance imaging (MRI) studies were performed in 16 patients 3 to 28 months postoperatively; MRI was repeated in 5 cases 12 to 18 months after the first radiological study.

Results

The voice quality of all patients improved after surgery, and long-term stability was confirmed by MPT, GRBAS, and VHI ( P ranging between .004 and <.001). The results achieved 1 year postoperatively remained stable at 3 and 10 years. Videolaryn-gostroboscopy showed improved glottic closure in all patients despite a limited amount of fat resorption. CT and MRI demonstrated survival of the fat grafts in all of the 16 examined cases. Serial MRI scans showed no change in graft size over time.

Conclusions

The reported clinical and radiological data demonstrate that fat is an effective filler for permanent vocal fold augmentation if the refined micro-aliquots are placed in multiple tunnels.

Mechanical Supplementation With the Stromal Vascular Fraction Yields Improved Volume Retention in Facial Lipotransfer: A 1-Year Comparative Study

Background

Unpredictable volume maintenance in the long term is a major limitation of autologous fat grafting.

Objectives

The authors compared results of autologous lipotransfer to the face with or without enrichment of fat with the stromal vascular fraction (SVF).

Methods

Thirty patients with asymmetric depletion of facial volume were included in a prospective study. Patients were randomly assigned to undergo a single session of autologous fat transfer with washed adipose tissue (control group) or with washed adipose tissue combined with the pellet of centrifuged lipoaspirate, which contained the SVF (enriched group). Patients were evaluated clinically and from photographs. A subset of 5 patients in each group underwent computed tomography (CT) preoperatively and 12-months postoperatively for quantitative assessment of graft retention. Washed and fractionated lipoaspirates were evaluated histochemically and with flow cytometry to determine relative abundances of viable cells.

Results

No major complications occurred. CT findings 12 months postoperatively indicated that patients who received SVF-enriched fat had significantly better volume retention (9.6% volume loss vs 24% in the control group; P = 0.013). Independent surgeons more frequently rated long-term aesthetic outcomes as "excellent" for patients in the enriched group (82.5% vs 47.6% for control group). Laboratory results indicated that each pellet contained approximately 16,000 intact adipose-derived stem cells.

Conclusions

Lipotransfer with SVF-enriched adipose tissue is safe and associated with improved volume retention, compared with transplantation of unenriched fat. The SVF can be dissociated from lipoaspirate by centrifugation to yield a large quantity of viable regenerative cells, without enzymatic digestion.

Level of Evidence

2.