Fat Graft Enrichment Strategies: A Systematic Review

Disulfiram Improves Fat Graft Retention by Modulating Macrophage Polarization With Inhibition of NLRP3 Inflammasome-Mediated Pyroptosis

BACKGROUND

Macrophage-mediated inflammatory response in the early post-grafting period restricts fat graft retention. Pyroptosis is a novel type of programmed cell death that extensively participates in inflammatory pathologies.

OBJECTIVES

This study sought to determine whether macrophage pyroptosis was activated during the inflammatory phase after fat grafting and to investigate the efficacy of a pyroptosis inhibitor, disulfiram (DSF), in fat graft retention.

METHODS

We established a C57BL/6 mice fat grafting model and then analyzed macrophage pyroptosis. DSF (50 mg/kg, every other day) was intraperitoneally injected starting 1 hour before fat grafting and continued for 14 days. An in vitro co-culture system was established in which mouse RAW264.7 macrophages were co-cultured with apoptotic adipocytes to further validate the findings of the in vivo studies and to explore the underlying mechanisms.

RESULTS

Here we reported that macrophage pyroptosis was activated in both fat grafts and in vitro co-culture models. DSF was found to be a potent pyroptosis inhibitor, promoting M2 macrophage polarization. In addition, DSF was demonstrated to enhance vascularization and graft retention.

CONCLUSIONS

Our results suggested that pyroptosis plays a crucial role in the inflammatory cascade within fat grafts. DSF, being a clinically available drug, could be translated into a clinically effective drug for improving fat graft survival by inhibiting macrophage pyroptosis, therefore inducing M2 macrophage polarization and promoting neovascularization.

Increased Total Antioxidant Capacity Value Improves Survival of Fat Grafts in Rat Model

BACKGROUND

Although studies aiming to increase fat graft survival continue, in this study, the authors aimed to investigate the effects of different antioxidants on total antioxidant capacity (TAC) and their effect on graft survival.

METHODS

Thirty-two male Wistar rats were divided into four equally sized groups, including a control group and three antioxidant groups receiving either melatonin (10 mg/kg), zinc (2 mg/kg), or vitamins E and C (100 mg/kg). Autologous fat grafts (1.7 ± 0.4 g) were transferred to the dorsal subcutaneous region, and total antioxidant capacity was measured on days 0 and 1, week 1, and monthly until the third month. Transferred graft volume and mass (1.3 ± 0.4 g) were measured using the liquid overflow method and precision scales at the end of the study. Routine hematoxylin and eosin staining and immunohistochemistry against perilipin were performed for semiqualitative analysis and H-score for viable adipose cells, respectively.

RESULTS

Collected fat grafts measured significantly less in weight and volume and the survival rate was lower in the control group ( P < 0.01). The control group exhibited a reduction in TAC, whereas all groups receiving antioxidants had an increase in TAC during the first week ( P = 0.02, P = 0.008, and P = 0.004 for melatonin, zinc, and vitamins, respectively). Immunohistochemistry of the antioxidant group demonstrated a statistically significant excess and reactivity of cells staining with perilipin antibodies.

CONCLUSION

In this animal study, the beneficial effect of antioxidants on fat graft survival can be related to the significant increase in TAC following the first week of their administration.

CLINICAL RELEVANCE STATEMENT

Antioxidants improve fat graft survival and quality in this rat model, by increasing total antioxidant capacity in the first week of administration.

Facial cosmetic injection: A bibliometric analysis of research status and hotspots

BACKGROUND

The increasing popularity of cosmetic injections using various fillers and neuromodulators for facial rejuvenation has brought both new opportunities and challenges to this field.

AIM

Our study was designed to employ bibliometric and visual analysis for a qualitative and quantitative evaluation of facial cosmetic injections, as well as to identify research trends and hotspots in this field.

METHODS

All publications covering facial cosmetic injection during 2002-2023 were retrieved and extracted from the Web of Science database. The VOSviewer 1.6.18 software and the online tool (http://bibliometric.com/) were applied to analyze the publication trend.

RESULTS

A total of 3797 articles related to facial cosmetic injection were identified during the period 2002-2023. The United States had the largest volume of publications (1520, 40.0%), followed by China (333, 8.8%) and Germany (282, 7.3%). Among the institutions and journals, the University of California system and Plastic and Reconstructive Surgery accounted for the most papers related to facial cosmetic injection, respectively. Facial anatomy and injection techniques, prevention and management of complications, regenerative medicine, efficacy and safety of various soft-tissue fillers, as well as botulinum toxin injections for facial rejuvenation were identified as hotspots for facial cosmetic injections.

CONCLUSIONS

Facial cosmetic injections are showing an increasing trend in terms of both the number of published papers and operations performed. Despite the notable advancements in this field, numerous challenges persist, including safety concerns and the level of research evidence. With the emergence of novel technologies and materials, scholars from diverse countries and institutions should engage in more extensive collaboration, thereby directly expediting the progress of this field.

Contemporary Prophylactic Antibiotic Practices and Adjunct Therapies in Autologous Fat Grafting Procedures: A Survey of The Aesthetic Society Members

Background

Autologous fat grafting (AFG) is a widely used surgical technique that involves extracting a patient's own adipose tissue and transferring it to different areas of the body. This practice is still evolving. Guidelines for antibiotic prophylaxis and use of adjuncts in plastic surgery are currently limited, with a notable absence of standardized guidelines for AFG.

Objectives

In this survey, we assess contemporary antibiotic practices and adjuncts in AFG procedures.

Methods

A 52-question survey was emailed to 3106 active members of The Aesthetic Society. Two hundred and ninety-three responses were recorded, representing a 9% response rate.

Results

We analyzed 288 responses. The most common AFG procedures were facial (38%), gluteal (34%), and breast (27%) augmentation. Preoperative antibiotics were used by 84.0% overall, with rates of 74.3%, 88.0%, and 92.7% in face, breast, and gluteal AFG, respectively. Lipoaspirate-antibiotic mixing was reported by 19.8%, mainly during gluteal AFG (46.9%), and less so in face (2.8%) and breast (8%) AFG. Notably, 46.9% of surgeons administered prolonged prophylaxis for 72 h or more. Tranexamic acid was utilized by 39.9% of the surveyed surgeons. Platelet-rich plasma was used by 5.6%. Doppler ultrasound was incorporated by 16.7% in AFG, with 21.5% in gluteal AFG, 14% in the face, and 19% in breast procedures.

Conclusions

In this survey, we offer insights into antibiotic practices and adjunct therapies in AFG, especially intraoperative antibiotic mixing. Practices among members of The Aesthetic Society vary from guidelines. It is crucial to standardize practices and conduct further research to pave the way for evidence-based guidelines in AFG.

Level of Evidence 5

Effects of Age on the Biological Properties of Cryopreserved Adipose-Derived Stem Cells and ASC-Enriched Fat Grafts

BACKGROUND

Donor age is an important factor affecting the biological characteristics of human adipose-derived stem cells. The aim of this study was to compare the effects of age on the biological properties of cryopreserved adipose-derived stem cells and fat survival of cell-assisted lipotransfer.

METHODS

Human lipoaspirates were obtained from 60 healthy female patients (aged 18-65 years) who underwent abdominal liposuction. Samples were divided into three groups according to donor age: group A, 18-29 years; group B, 30-49 years; and group C, 50-65 years. Adipose-derived stem cells were obtained by in vitro culture at the second passage and cryopreserved for 4 weeks. The cryopreserved ASCs were examined for biological characteristics, including cell proliferation, wound healing and adipogenic differentiation. Then, the fat survival of cryopreserved ASC-assisted fat transplantation was compared at different ages.

RESULTS

SVF viability decreased with increasing age. Moreover, there was a decline in cell proliferation and migration of ASCs with increasing age. A significant difference was found in the adipogenic differentiation of ASCs in the three groups. There were significant differences in graft retention in different age groups. ASC-assisted fat grafting was more effective in young people than in elderly people.

CONCLUSIONS

Honor age affects the proliferation and migration of adipose-derived stem cells but not the adipogenic differentiation potential of ASCs. Cryopreserved ASCs from younger people more effectively improved the fat survival of grafts.

LEVEL OF EVIDENCE V

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 .

Positive effects of hypoxic preconditioning of the extracellular matrix and stromal vascular fraction from adipose tissue

Background

Numerous approaches have been developed to decelerate the aging process of facial skin. Synthetic fillers and cell-enriched fat grafts are the main procedures employed to fill wrinkles.

Objective

The aim of this study was to evaluate the in vitro and in vivo safety and efficiency of a new process developed by SYMBIOKEN: the AmeaCell, which facilitates the extraction of the stromal vascular fraction (SVF) and the associated hypoxia pre-conditioned matrix to promote fat graft survival.

Methods

The AmeaCell device allows the extraction from adipose tissue of SVF and pre-conditioned MatriCS and promotes a hypoxic environment. Experiments were carried out on human cells and then in mice.

Results

Characterization of cells and MatriCS showed that after their extraction using the new process developed by SYMBIOKEN, the extracted cells expressed stem-cell markers. The presence of characteristic proteins and lipid fractions found in the adipose matrix were confirmed in MatriCS. Cobalt chloride treatment of the matrix using the AmeaCell device induced modifications in the matrix composition with a decrease in laminin and without collagen modification, both of which promote adhesion and differentiation of SVF or adipose-derived stromal cells. The combination of MatriCS and SVF (1 × 106 and 5 × 106, respectively) is safe and efficient to fill winkles induced by UVB irradiation. The cross-talk between MatriCS and SVF can act a durable filler compared to the filling performed using cells or matrix or fat alone, which need to be replaced frequently.

Conclusion

These results indicate that the combination of MatriCS and SVF is safe and effective as a biological filler for achieving skin rejuvenation and wrinkle filling.

Evaluating the quality of studies reporting on clinical applications of stromal vascular fraction: A systematic review and proposed reporting guidelines (CLINIC-STRA-SVF)

Background

The stromal vascular fraction (SVF) has been widely explored in a number of therapeutic applications in several specialties. Its therapeutic potential is being increasingly demonstrated, although its mechanism of action is still unclear.

Objective

To evaluate the quality of studies reporting on clinical applications of SVF.

Method

This is a systematic literature review that followed the PRISMA guidelines with the search of the studies from December 1, 2012, to December 1, 2022, in the following databases: MEDLINE, LILACS and EMBASE. The level of evidence of the studies was assessed using the GRADE system, and the rigor used in the publication of the results was assessed in relation to adherence to the guidelines indicated by the EQUATOR Network Group. The CLINIC - STRA-SVF reporting guideline was developed after the completion of this systematic review.

Results

A total of 538 articles were found, and 77 articles were selected after reading the titles and abstracts and removing duplicates. Then, 15 studies were removed for not meeting the inclusion criteria, leaving 62 studies. The CLINIC - STRA-SVF was developed and consists of 33 items and two tables.

Conclusion

There is scientific evidence, although mostly with a low level of evidence, that the use of SVF in clinical applications is safe and effective. The information published in these studies should be standardized, and the CLINIC - STRA-SVF reporting guideline proposed in this study may assist in the design, conduct, recording and reporting of clinical trials and others clinical studies involving the SVF.

Exosomes Derived from Human Adipose-Derived Stem Cells Cannot Distinctively Promote Graft Survival in Cryopreservation Fat Grafting

BACKGROUND

Cryopreserved fat has limited clinical applications due to its rapid absorption, high degree of fibrosis, and risk of complications after grafting. Many studies have verified that Adipose-derived mesenchymal stem cell-derived exosomes (ADSC-Exos) can improve fresh fat graft survival. This study assessed whether ADSC-Exos could improve the survival of cryopreserved fat grafts.

METHODS

Exosomes were isolated from human ADSCs were subcutaneously engrafted with adipose tissues stored under different conditions (fresh; cryopreserved for 1 month) into the backs of BALB/c nude mice (n = 24), and exosomes or PBS were administered weekly. Grafts were harvested at 1, 2, 4, and 8 weeks, and fat retention rate, histologic, and immunohistochemical analyses were conducted.

RESULTS

At 1, 2, and 4 weeks after the transfer, cryopreserved fat grafts in groups of exosome-treated showed better fat integrity, fewer oil cysts, and reduced fibrosis. Further investigations of macrophage infiltration and neovascularization revealed that those exosomes increased the number of M2 macrophages at 2 and 4 weeks (p<0.05), but had limited impact on vascularization (p>0.05). It's important to note that no significant differences (p>0.05) were observed between the two groups in both histological and immunohistochemical evaluations at 8 weeks post-transplantation.

CONCLUSIONS

This study suggests that ADSC-Exos could improve the survival of cryopreserved fat grafts in the short term (within 4 weeks), but the overall improvement was poor (after 8 weeks). This suggests that the utility of using ADSC-Exos to treat cryopreserved adipose tissue grafts is limited.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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 .

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 .

Current Fat Grafting Practices and Preferences: A Survey from Members of ISPRES

Fat grafting has established its niche in a wide spectrum of aesthetic and reconstructive procedures. A consensus-based method of harvest, processing, enrichment, injection, and assessment is lacking, despite the rising trends in its application. We conducted a survey among plastic surgeons to evaluate and identify trends of fat grafting practices.

Oncologic Safety and Efficacy of Cell-Assisted Lipotransfer for Breast Reconstruction in a Murine Model of Residual Breast Cancer

BACKGROUND

Cell-assisted lipotransfer (CAL) is a novel technique for fat grafting that combines the grafting of autologous fat and adipose-derived stromal cells (ASCs) to enhance fat graft retention; however, its oncologic safety is controversial.

METHODS

Herein, we investigated the oncologic safety of CAL for breast reconstruction using a murine model of residual breast cancer. Various concentrations of 4T1 cells (murine breast cancer cells) were injected into female mastectomized BALB/c mice to determine the appropriate concentration for injection. One week after injection, mice were divided into control (100 μL fat), low CAL (2.5 × 10⁵ ASCs/100 μL fat), and high CAL (1.0 × 10⁶ ASCs/100 μL fat) groups, and fat grafting was performed. The injection of 5.0 × 10³ 4T1 cells was appropriate to produce a murine model of residual breast cancer.

RESULTS

The weight of the fat tumor mass was significantly higher in the high CAL group than in the other groups (p < 0.05). However, the estimated tumor weight was not significantly different between the groups. Additionally, the fat graft survival rate was significantly higher in the high CAL group than in the control and low CAL groups (p < 0.05). No significant difference was noted in the percentage of Ki-67-positive cells, suggesting that tumor proliferation was not significantly different between the groups.

CONCLUSION

In summary, CAL significantly improved fat graft survival without affecting tumor size and proliferation in a murine model of residual breast cancer. These results highlight the oncologic safety of CAL for breast reconstruction.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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 .

Adipose-derived stem cells exosome and its potential applications in autologous fat grafting

Recently, there has been renewed interest in autologous fat grafting both for its filler and regenerative traits. The universal application, however, has been impeded by the unstable survival rates and complications. There has been substantial research undertaken on the role of adipose-derived stem cells (ADSCs) involved in fat graft fates including angiogenesis, adipogenesis, and inflammatory regulation. As the effectors of their parental cells, ADSC-derived exosomes (ADSC-exos) encapsulating multiple bioactive cargoes mediate cell-to-cell communication in a paracrine manner. ADSC-exos have received much attention for their biocompatible and efficient therapeutic potentials as "cell-free therapy" in plastic surgery, including increasing fat grafting survival rates. In this review, we summarize the current knowledge about the biological basis of ADSC-exos, ADSC-related mechanisms of fat survival, research updates of ADSC-exos in autologous fat grafting, and discuss some challenges along with research prospects.

Supplementation of Facial Fat Grafting to Increase Volume Retention: A Systematic Review

BACKGROUND

For decades, facial fat grafting has been used in clinical practice for volume restoration. The main challenge of this technique is variable volume retention. The addition of supplements to augment fat grafts and increase volume retention has been reported in recent years.

OBJECTIVES

The aim of this systematic review was to investigate which supplements increase volume retention in facial fat grafting as assessed by volumetric outcomes and patient satisfaction.

METHODS

Embase, Medline, Ovid, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and Google Scholar were searched up to November 30, 2020. Only studies assessing volume after facial fat grafting with supplementation in human subjects were included. Outcomes of interest were volume or patient satisfaction. The quality of the studies was assessed with the Effective Public Health Practice Project tool.

RESULTS

After duplicates were removed 3724 studies were screened by title and abstract. After reading 95 full-text articles, 27 studies were eligible and included for comparison. Supplementation comprised of platelet-rich plasma, platelet-rich fibrin, adipose tissue-derived stromal cells or bone marrow-derived stromal cells, cellular or tissue stromal vascular fraction, or nanofat. In 13 out of 22 studies the supplemented group showed improved volumetric retention and 5 out of 16 studies showed greater satisfaction. The scientific quality of the studies was rated as weak for 20 of 27 studies, moderate for 6 of 27 studies, and strong for 1 study.

CONCLUSIONS

It remains unclear if additives contribute to facial fat graft retention and there is a need to standardize methodology.

LEVEL OF EVIDENCE: 4

Plasminogen-derived peptide promotes adipogenic differentiation of preadipocytes in vitro and in vivo

Soft tissue defects caused by adipose tissue loss can result in various conditions such as lipodystrophy in congenital diseases, trauma secondary to ageing, and mastectomy in breast cancer; fat grafting is commonly performed to restore these defects. Although various enrichment strategies have been studied, novel therapeutics that are cost-effective, safe, technologically easy to manufacture, and minimally invasive are required. In this study, we identified a novel peptide derived from plasminogen, named plasminogen-derived peptide-1 (PLP-1), which showed adipogenic differentiation potential and led to an increase in the expression levels of adiponectin, C1Q and collagen domain containing protein, fatty acid-binding protein 4, and CCAAT/enhancer-binding protein-alpha. In vivo experiments confirmed an increase in the rate of adipocyte differentiation and the expression levels of CD31 in the PLP-1-treated mice groups. These results suggested that PLP-1 plays an important role in promoting the differentiation of preadipocytes and may be useful for developing therapeutic approaches to treat adipose tissue defects.

Role of adipose tissue grafting and adipose-derived stem cells in peripheral nerve surgery

The application of autologous fat grafting in reconstructive surgery is commonly used to improve functional form. This review aims to provide an overview of the scientific evidence on the biology of adipose tissue, the role of adipose-derived stem cells, and the indications of adipose tissue grafting in peripheral nerve surgery. Adipose tissue is easily accessible through the lower abdomen and inner thighs. Non-vascularized adipose tissue grafting does not support oxidative and ischemic stress, resulting in variable survival of adipocytes within the first 24 hours. Enrichment of adipose tissue with a stromal vascular fraction is purported to increase the number of adipose-derived stem cells and is postulated to augment the long-term stability of adipose tissue grafts. Basic science nerve research suggests an increase in nerve regeneration and nerve revascularization, and a decrease in nerve fibrosis after the addition of adipose-derived stem cells or adipose tissue. In clinical studies, the use of autologous lipofilling is mostly applied to secondary carpal tunnel release revisions with promising results. Since the use of adipose-derived stem cells in peripheral nerve reconstruction is relatively new, more studies are needed to explore safety and long-term effects on peripheral nerve regeneration. The Food and Drug Administration stipulates that adipose-derived stem cell transplantation should be minimally manipulated, enzyme-free, and used in the same surgical procedure, e.g. adipose tissue grafts that contain native adipose-derived stem cells or stromal vascular fraction. Future research may be shifted towards the use of tissue-engineered adipose tissue to create a supportive microenvironment for autologous graft survival. Shelf-ready alternatives could be enhanced with adipose-derived stem cells or growth factors and eliminate the need for adipose tissue harvest.

The Effect of Human Umbilical Cord-Derived Lyophilized Stem Cells on Fat Graft Viability: An Experimental Study

OBJECTIVE

The extended use of autologous adipose tissue has increased the importance of the viability of fat graft cells. This experimental animal study assesses the effects of lyophilized mesenchymal stem cells on the viability and survival of autologous fat grafts.

METHODS

For this prospective treatment control study, 27 male Wistar albino rats were divided into three groups, each containing nine animals. In Group 1 (control), an incision was made in the right inguinal region, and the skin was closed with 4/0 prolene sutures. In Groups 2 and 3, fat pads collected from the right groin of the rats were lipoaspirated and placed on the sternum as a subcutaneous fat graft. The skin was then closed with 4/0 prolene sutures. Saline was added to the fat grafts of the Group 2 (sham) rats, and placenta-derived mesenchymal stem cell lyophilizate (MSC-L) was administered to the fat graft in the Group 3 (treatment) rats. After three months of treatment, the adipose tissue harvested from Group 1 and the fat grafts taken from Groups 2 and 3 were assessed histopathologically, stereologically and biochemically.

RESULTS

Adipose tissue volume was lower in Group 2 than in Groups 1 and 3, and the adipose tissue treated with MSC-L in Group 3 was better preserved than that in Group 1. Connective tissue and vascular volumes were greater in Group 3 than those in the other groups. The normal structures of adipocytes, fibrous tissues and vessels were better preserved in Group 3 than in Group 2, and a large number of new blood vessels were noted to have formed in Group 3. Damaged cystic cells, areas of calcification and degenerated adipocytes were noted in Group 2, while the G3PDH levels increased significantly more in Group 3 than in Group 2.

CONCLUSION

It was shown that MSC-L treatment plays an active role in maintaining the volume and survival of fat grafts by promoting neovascularization in this animal experimental study.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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.

Protein profiling of mechanically processed lipoaspirates: discovering wound healing and anti-fibrotic biomarkers in nanofat

BACKGROUND

Nanofat is an injectable oily emulsion, rich in adipose derived stem cells (ADSCs) and growth factors. It is prepared from lipoaspirates through mechanical emulsification and filtration. Despite being successfully used in several procedures in regenerative medicine such as scar attenuation, skin rejuvenation and treatment of chronic wounds, little is known about exactly how nanofat induces regeneration in treated skin at the molecular level.

METHODS

Microfat and nanofat samples were isolated from 18 healthy patients. Proteomic profiling was performed through untargeted mass spectrometry proteomics and multiplex antibody arrays. Pathway enrichment analysis of differentially expressed proteins between microfat and nanofat was performed using Gene Ontology, Reactome and KEGG as reference databases.

RESULTS

Untargeted proteomics showed that upregulated genes in nanofat are involved in innate immunity responses, coagulation and wound healing, while downregulated genes were linked to cellular migration and extracellular matrix (ECM) production. Secretome array screening of microfat and nanofat samples showed no significantly different expression, which strongly suggests that the mechanical emulsification step does not affect the concentration of tissue regeneration biomarkers. The identified proteins are involved in wound healing, cellular migration, extracellular matrix remodelling, angiogenesis, stress response and immune response.

CONCLUSIONS

Mechanical processing of lipoaspirates into nanofat significantly influences the proteome profile by enhancing inflammation, antimicrobial and wound healing pathways. Nanofat is extremely rich in tissue repair and tissue remodelling factors.

CLINICAL RELEVANCE STATEMENT

This study shows that the effects of Micro- and Nanofat treatment are based on upregulated inflammation, antimicrobial and wound healing pathways. Mechanical emulsification does not alter the concentration of tissue regeneration biomarkers.

The Importance of Protecting the Structure and Viability of Adipose Tissue for Fat Grafting

BACKGROUND

Fat grafting is widely used for soft-tissue augmentation; however, the related clinical outcome remains variable and technique-dependent. The mechanisms underlying fat graft survival are not fully understood, particularly regarding the contributions of different cell types, such as functional adipocytes. This study evaluated the importance of adipose tissue structure and viability in fat grafting and, to some extent, revealed the effect of adipocytes in fat grafting.

METHODS

Human lipoaspirate was harvested using suction-assisted liposuction and processed using three separate methods: cotton-pad filtration, soft centrifugation (400 g for 1 minute), and Coleman centrifugation (1200 g for 3 minutes). Then all samples were subjected to second cotton-pad concentration. Adipose tissue structure and viability, the numbers of adipose-derived stem cells, and their proliferation and multilineage differentiation abilities were compared in vitro. The volume retention rate and fat graft quality were evaluated in vivo.

RESULTS

Cell structure destruction and viability decline were more evident in the Coleman centrifugation group compared to the cotton-pad filtration group and the soft centrifugation group. However, no intergroup differences were observed in the numbers, proliferation, or multilineage differentiation abilities of adipose-derived stem cells. After transplantation, the volume retention rates were similar in the three groups. However, greater structural and functional damage was associated with poorer graft quality, including decreased levels of graft viability, vessel density, and vascular endothelial growth factor secretion and increased levels of vacuoles, necrotic areas, fibrosis, and inflammation.

CONCLUSIONS

Protecting adipose tissue structure and viability is crucial for improving fat grafting outcomes.

CLINICAL RELEVANCE STATEMENT

The protection of the structure and viability of adipose tissue should be ensured throughout the whole process of fat grafting to reduce complications and improve graft quality.

Cell-Assisted Lipotransfer in Breast Augmentation Surgery: Clinical Outcomes and Considerations for Future Research

Autologous fat transfer is a widely used surgical technique, chosen by numerous plastic surgeons for breast augmentation surgery. This technique is based on three steps: 1. harvesting of the lipoaspirate from the patient, 2. centrifugation and removal of the top, oily, layer, and 3. implantation in the patient’s breast(s). It has been associated with various complications, including post-surgical fat resorption, as measured quantitatively with MRI, CT, and other 3D-quantification systems.

Adipose-derived stem cells have been explored as a means of addressing fat resorption. They can be separated from the lipoaspirate following centrifugation, and enzymatically purified from unwanted debris, with collagenase, forming the stromal vascular fraction. The stromal vascular fraction is then recombined with the graft volume prior to implantation. This novel technique, referred to as “cell-assisted lipotransfer”, has shown promising results in terms of reducing fat resorption. These results are due to the pro-angiogenic and pro-adipogenic ability of the stem cells, which allow the graft to address the conditions of ischemia more effectively than autologous fat transfer.

The aim of this review is to explore the ways in which cell-assisted lipotransfer is different from the autologous fat transfer, as well as how and why adipose-derived stem cells may contribute towards limiting fat resorption. The immunological background of these cells is discussed in detail, while grounds for further development are discussed, by means of the administration of external growth factors, which could, potentially, maximize outcomes, while limiting complications.

The Influence of Low- and High-Negative-Pressure Liposuction and Different Harvesting Sites on the Viability and Yield of Adipocytes and Other Nucleated Cells

BACKGROUND

The volume effect of fat grafting is highly dependent on the presence of viable adipocytes and other nucleated cells within the lipoaspirate. We suspected that one of the crucial factors influencing cell viability is the negative pressure applied during the fat graft harvesting and the suitability of various harvest sites when compared to others. Despite much discussion, there is no consensus on the optimal negative pressure or the best site for harvesting so we designed an experiment to test this.

METHODS

Fat graft taken under low negative pressure (- 200 mmHg) or high negative pressure (- 700 mmHg) from the thigh or abdominal regions from 21 healthy human donors was evaluated. The principal variables studied were: a) total number and viability of nucleated cells, b) liposuction duration and c) blood admixture. Other variables studied were body mass index, the impact of age and enzymatic digestion.

RESULTS

The absolute number and viability of nucleated cells and the blood admixture did not differ significantly between lipoaspirates obtained under different vacuum conditions or from different regions. The time taken to acquire the same volume of lipoaspirate was significantly increased using low negative pressure. The time taken to collect cells in the thigh region significantly increased with increasing BMI but this correlation was not found when harvesting in the abdominal region. The BMI and age did not impact the results in any of the measured variables. The enzymatic digestion rate was independent of the negative pressure used to harvest.

CONCLUSION

Our results indicate that neither the negative pressure used nor the area chosen has any significant influence on the viability and yield of harvested cells. The time taken to obtain lipoaspirate using low pressure is significantly longer than when using high pressure. No significant difference was found in the value of blood admixture using different vacuum pressures, and no correlation exists between the body mass index and the cell viability or age of the patients and the time of liposuction.

LEVEL OF EVIDENCE III

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 Table of Contents or online Instructions to Authors www.springer.com/00266 .

Fractional Carbon Dioxide Laser or Erbium:Yttrium-Aluminum-Garnet Laser Assisted by Topical Application/Intradermal Injection of Platelet-Rich Plasma for Postacne Scars

BACKGROUND

Fractional carbon dioxide or erbium:yttrium-aluminum-garnet (YAG) laser combined with platelet-rich plasma has been used for postacne scars. Nevertheless, there is limited evidence on its use because of the small size of relevant studies. This study aims to evaluate the efficacy of platelet-rich plasma-assisted laser for postacne scars.

METHODS

Randomized controlled trials comparing carbon dioxide or erbium:YAG laser combined with platelet-rich plasma to laser alone were searched for using the PubMed, Embase, Web of Science, Cochrane Library, and Google Scholar databases.

RESULTS

In total, 13 studies involving 672 cases were included. The overall degree of clinical improvement favored platelet-rich plasma combined with carbon dioxide laser (mean difference, 0.55; 95 percent CI, 0.40 to 0.70) or erbium:YAG laser (mean difference, 0.63; 95 percent CI, 0.31 to 0.96). Notably, the use of carbon dioxide laser combined with platelet-rich plasma was more effective in both greater than 50 percent improvement of acne scars (OR, 1.63; 95 percent CI, 1.10 to 2.42) and greater than 75 percent improvement of acne scars (OR, 2.78; 95 percent CI, 1.75 to 4.42), compared with laser alone. Erbium:YAG laser combined with platelet-rich plasma was more effective in greater than 75 percent improvement of acne scars compared with laser alone (OR, 3.45; 95 percent CI, 1.31 to 9.05). Moreover, patient satisfaction was significantly higher with platelet-rich plasma combined with carbon dioxide laser (OR, 2.98; 95 percent CI, 1.72 to 5.16) or erbium:YAG laser (OR, 2.88; 95 percent CI, 1.33 to 6.21) compared to laser alone.

CONCLUSION

This meta-analysis provides reliable evidence that fractional carbon dioxide or erbium:YAG laser combined with platelet-rich plasma is an effective and safe combination therapy for postacne scars.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

"Fasting: An Effective Preconditioning Method to Increase Fat Graft Survival"

BACKGROUND

Most preconditioning techniques before fat grafting require external manipulation. Since nutrition is the main factor maintaining the balance of lipogenesis and lipolysis, we hypothesized that fasting before undergoing autologous fat grafting may increase lipolysis and reduce adipocyte size, thereby improving the fat graft survival rate.

METHODS

C57BL/6 mice were divided into 24 h starved or fed groups. Adipose tissue lipolysis, adipogenesis, and angiogenesis-related gene expression, in fat from both groups, were analyzed. The volume and weight of the grafted fat at 4-8 weeks postoperatively were measured using micro-computed tomography. Immunohistochemistry staining and mRNA expression analysis were also performed to evaluate the effect of fasting on fat graft survival.

RESULTS

Fasting decreased adipocyte size by inducing adipose tissue lipolysis. Adipogenesis-related genes were remarkably downregulated while lipolysis-related genes and angiogenesis inducer genes were significantly upregulated in the starved adipose tissue. The mice grafted with the fat from the 24 h starved group had approximately 20% larger volumes and considerably heavier weights than those from the fed group. Increased viable adipocytes and vessels, and reduced macrophages in the fat grafts obtained from the 24 h starved group were also observed.

CONCLUSIONS

Fasting for 24 h before harvesting fat increased the retention volume of fat graft by increasing angiogenesis via VEGF induction. Therefore, fasting would be a novel and reliable preconditioning strategy to improve graft survival in autologous fat grafting.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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.

UK Guidelines for Lipomodelling of the Breast on behalf of Plastic, Reconstructive and Aesthetic Surgery and Association of Breast Surgery Expert Advisory Group

Lipomodelling has become increasingly popular for reconstructive, aesthetic and therapeutic indications. The guidelines summarise available evidence for indications, training, technique, audit and outcomes in lipomodelling and also highlight areas for further research.

The Influence of High and Low Negative Pressure Liposuction and Various Harvesting Techniques on the Viability and Function of Harvested Cells-a Systematic Review of Animal and Human Studies

BACKGROUND

An understanding of fat grafting methodology, techniques and patient-related factors is crucial when considering fat grafting. Multiple factors can influence the success of a fat graft and consequently the outcome of the procedure. The aim of this systematic review is to elucidate the influence of negative pressure and various techniques of fat harvesting on the viability and function of cells, particularly adipocytes and adipose-derived stem cells.

METHODS

We conducted a literature search from 1975 to 2020 using the PubMed bibliography, ScienceDirect, SCOPUS and the Google Scholar databases which produced 168,628 articles on the first pass. After applying all the exclusion criteria by two independent reviewers, we were left with 21 articles (level IV of Oxford Centre for Evidence-Based Studies and Grade C of Grade Practice Recommendation from the American Society of Plastic Surgeons) on which this review is based.

RESULTS

From 11 studies focused on different negative pressures, no one found using high negative pressure advantageous. Summarising 13 studies focused on various harvesting techniques (excision, syringe, and pump-machine), most often equal results were reported, followed by excision being better than either syringe or liposuction.

CONCLUSION

From our systematic review, we can conclude that the low negative pressure seems to yield better results and that the excision seems to be the most sparing method for fat graft harvesting. However, we have to point out that this conclusion is based on a very limited number of statistically challengeable articles and we recommend well-conducted further research.

LEVEL OF EVIDENCE III

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 Effect of Lipoaspirate Processing Technique on Complications in Autologous Fat Grafting for Breast Reconstruction: A Propensity Score Analysis Study

BACKGROUND

The use of autologous fat grafting (AFG) is becoming increasingly common as an adjunct to breast reconstruction. However, there is a paucity of data comparing the varying processing devices.

OBJECTIVES

The goal of this study was to compare the outcomes of 2 commercially available AFG processing devices.

METHODS

A retrospective review was conducted of patients who underwent AFG with dual-filter (Puregraft) or single-filter (Revolve) processing systems between 2016 and 2019. Propensity score matching was utilized to adjust for confounding. A total of 38 breasts from the Puregraft group were matched with 38 breasts from the Revolve group.

RESULTS

Matching was successful in achieving a similar distribution of baseline characteristics between the 2 groups. The mean number of AFG sessions was comparable between the 2 groups (P = 0.37) with a similar median total volume (Puregraft, 159 mL vs Revolve, 130 mL; P = 0.23). Complication rates were similar between the 2 devices (Puregraft, 26%; Revolve, 18%; P = 0.47). Patients with at least 1 complication had higher overall AFG volume (median, 200 mL vs 130 mL; P = 0.03) and number of sessions (mean, 2.4 vs 1.8, P = 0.009) compared with those without any postoperative complication.

CONCLUSIONS

Overall complication rates were comparable between 2 commonly used, commercially available AFG processing systems, and therefore the choice of which to use should be based on surgeon preference. Future studies are underway to decipher whether either system offers superior graft retention, cosmetic, or patient-reported outcomes.

LEVEL OF EVIDENCE: 3

Update on the Basic Science Concepts and Applications of Adipose-Derived Stem Cells in Hand and Craniofacial Surgery

SUMMARY

Adipose-derived stem cell therapy offers plastic surgeons a novel treatment alternative for conditions with few therapeutic options. Adipose-derived stem cells are a promising treatment because of their broad differentiation potential, capacity for self-renewal, and ease of isolation. Over the past decade, plastic surgeons have attempted to harness adipose-derived stem cells' unique cellular characteristics to improve the survival of traditional fat grafting procedures, a process known as cell-assisted lipotransfer. However, the full implications of cell-assisted lipotransfer in clinical practice remain incompletely understood, stressing the urgent need to assess the scientific evidence supporting adipose-derived stem cell-based interventions. Furthermore, with the strict regulatory climate surrounding tissue explantation therapies, reviewing the safety and efficacy of these treatments will clarify their regulatory viability moving forward. In this report, the authors provide a comprehensive, up-to-date appraisal of best evidence-based practices supporting adipose-derived stem cell-derived therapies, highlighting the known mechanisms behind current clinical applications in tissue engineering and regenerative medicine specific to plastic and reconstructive surgery. The authors outline best practices for the harvest and isolation of adipose-derived stem cells and discuss why procedure standardization will elucidate the scientific bases for their broad use. Finally, the authors discuss challenges posed by U.S. Food and Drug Administration oversight of these cell-based therapies and examine the role of adipose-derived stem cell-based applications in the future of plastic surgery.

The Efficacy of Cell-Assisted Lipotransfer Versus Conventional Lipotransfer in Breast Augmentation: A Systematic Review and Meta-Analysis

BACKGROUND

Cell-assisted lipotransfer (CAL) is novel and controversial technique for breast augmentation.

OBJECTIVE

This review and meta-analysis aimed to assess the clinical efficacy of CAL as compared with conventional lipotransfer.

METHODS

PubMed databases were searched with no restrictions for randomized controlled trials (RCTs) and observational studies with control groups. Keywords included "fat graft," "lipotransfer," "lipofilling," "autologous fat," "fat transplantation," "stromal vascular fraction (SVF)," "stem cell," "adipose tissue-derived stromal cell (ADSC)," "adipose tissue-derived stromal cell (ASC)," "called adipose derived progenitor cells (ADRC)," "cell-assisted," "progenitor-enriched," "cell-enhanced" and "breast." Review Manager software (RevMan, version 5.3) was used to compute the pooled effect estimates for fat survival rate and complication rates. Outcomes were expressed as standard mean differences (SMDs) or odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses were performed based on different methods of cell-enhanced fat preparation.

RESULTS

Six studies were included (n_total = 353 adult patients). The fat survival rate was significantly higher in the CAL group than in the control group (SMD = 1.79, 95% CI = 0.28, 3.31; P = 0.02). There were no significant differences in complication rates between the CAL group and the control group (OR = 1.34, 95% CI = 0.65, 2.73; P = 0.43). Subgroup analyses found no significant differences between the SVF and control groups in fat survival rate (SMD = 1.52, 95% CI = -0.21, 3.24; P = 0.08) among both manual and automatic subgroups (P = 0.28 and P = 0.10, respectively). The data analysis showed a significant heterogeneity between manual and automatic subgroups (I² = 57.0%, P = 0.15).

CONCLUSION

This study suggests that cell-assisted lipotransfer is superior to conventional lipotransfer for improved fat survival rate in breast augmentation. However, analyses comparing the SVF-enhanced fat graft with the conventional fat graft noted no differences in fat survival rate. It is necessary to determine which protocol is most beneficial for patients, establish standardized methods of SVF isolation or adipose tissue-derived stromal cells (ADSCs) culture, and a constant percentage of injected cells in the graft. The long-term efficacy and safety of CAL should also be evaluated in further studies, and additional RCTs with larger sample sizes and better comparability are needed.

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.

Does Water-Jet Force Affect Cryopreserved Adipose-Derived Stem Cells? Evidence of Improved Cell Viability and Fat Graft Survival

BACKGROUND

Adipose tissue harvested by liposuctions is an available source of adipose-derived stem cells (ASCs). Water-jet-assisted liposuction is a favorable method for fat collection with little mechanical damage. This study aimed to investigate whether or not the water-jet-assisted liposuction made a difference in the biological characteristics of cryopreserved ASCs and fat graft survival in cell-assisted lipotransfer.

METHODS

Human lipoaspirates were obtained from the abdomen or thighs of 20 female participants for body contouring. A single surgeon randomly harvested 50 mL of adipose tissue by the water-jet-assisted liposuction and the conventional liposuction, respectively. Adipose-derived stem cells were isolated from lipoaspirates and then cryopreserved for 4 weeks. Cryopreserved ASCs were used to examine the surface markers, cell proliferation, migration, and adipogenic differentiation in vitro. The fat survival of ASCs-enriched grafts from different liposuctions was measured in animal models.

RESULTS

The cryopreserved ASCs with the water-jet assistance had better capacities of cell proliferation, migration, and adipogenic differentiation and achieved a better survival result of ASCs-enriched fat grafting.

CONCLUSIONS

Cryopreservation of ASCs with the water-jet force showed more excellent biological characteristics. The water-jet-assisted liposuction was superior to the conventional liposuction in obtaining ASCs and fat survival of coimplantation with grafts.

Photobiomodulation with polychromatic light (600-1200 nm) improves fat graft survival by increasing adipocyte viability, neovascularization, and reducing inflammation in a rat model

OBJECTIVES

Unpredictability with the final volume and viability of the graft are the major concerns in fat grafting. An experimental study was conducted to increase graft retention using photobiomodulation (PBM) with polychromatic light in near-infrared region (600-1200 nm) by utilizing its stimulatory effects on angiogenesis, neovascularization, adipocyte viability, and anti-inflammatory properties.

METHODS

A total of 24 rats were divided into four groups (n = 6) according to the applied polychromatic light protocol to the recipient site (none, before fat transfer, after fat transfer, and combined). In all groups, inguinal fat pad was excised, measured for volume and weight, and transferred to the dorsum of the rat. At the end of the experiment, fat grafts were harvested from the recipient site for volume and weight measurements, histological, and immunohistochemical evaluation.

RESULTS

Intergroup comparison revealed that fat graft retention regarding weight and volume, was significantly superior in Group IV (p = 0.049 and p = 0.043, respectively), which polychromatic light was applied both before and after transfer of the graft. Hematoxylin-eosin and Masson's trichrome stained sections showed absence of necrosis, fibrosis, inflammation, cyst formation, and increased vascularization of both inner and outer zones of the grafts in Group IV. Also, immunohistochemical staining scores for perilipin (indicator for adipocyte viability), CD31 and VEGF (indicators for angiogenesis and neovascularization) were significantly higher (p < 0.001). Ki67 scores were significantly lower in this group because of anti-inflammatory environment (p < 0.001).

CONCLUSIONS

Application of PBM to the recipient site before and after fat transfer improved outcomes in rats at 56 day after fat grafting by means of volume retention, increased neovascularization and adipocyte viability and reduced necrosis, fibrosis and inflammation.

Letter to the Editor: The Efficacy of Cell-Assisted Lipotransfer Versus Conventional Lipotransfer in Breast Augmentation: A Systematic Review and Meta-Analysis

This is a letter to the editor about a meta-analysis titled "The efficacy of cell-assisted lipotransfer versus conventional lipotransfer in breast augmentation: a systematic review and meta-analysis" by Li and Chen published in the year 2021. The most frequently performed aesthetic procedure is breast augmentation surgery. In breast augmentation, cell-assisted lipotransfer (CAL) has received high recognition due to its positive outcomes. There are controversies in the medical literature on the use of CAL for breast augmentation. This meta-analysis by Li and Chen has concluded that CAL using ASC was superior to other methods as it improved fat survival rate in breast augmentation. We have written this letter to the editor of the Aesthetic Plastic Surgery journal about this meta-analysis because of its impactful information provided by this study to the medical literature for breast augmentation surgery using cell-assisted lipotransfer. Level of Evidence V 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.

Long-Term Effects of Platelet-Rich Fibrin on Fat Graft Survival and Their Optimal Mixing Ratio

BACKGROUND

Platelet-rich fibrin (PRF) can promote fat graft survival, but the reported mixing ratio of PRF to fat ranges from 1:25 to 1:2, lacking a clear standard for clinical application.

OBJECTIVES

The authors sought to explore the long-term effects of PRF on grafted fat and their optimal mixing ratio.

METHODS

Nude mice were randomly divided into a control group (receiving subcutaneous injection of fat granules) and 4 PRF groups (receiving subcutaneous injection of PRF and fat granules at volume ratios of 1:5, 1:10, 1:15, and 1:20, respectively). The graft samples (n = 12) were obtained in weeks 4, 8, and 12 to (1) calculate retention rates; (2) evaluate gene and protein expression of vascular endothelial growth factor A (VEGF-A), peroxisome proliferator-activated receptor-γ (PPAR-γ), type I collagen A1 (COL1-A1), and B-cell lymphoma-2 associated X protein (BAX); (3) perform hematoxylin and eosin, Masson's trichrome, α-smooth muscle action, and periplipin-1 stainings; and (4) count the microvessels and viable adipocytes.

RESULTS

Compared with the control group, PRF groups had higher retention rates, a higher gene/protein expression of VEGF-A, a lower gene/protein expression of COL1-A1 and BAX, less fibrosis, and more microvessels and viable adipocytes. Group 1:10 was superior to other groups in terms of retention rates and other evaluation indexes. The expression of PPAR-γ did not significantly differ among groups.

CONCLUSIONS

PRF may not play a long-term effect on adipogenesis, but it can still promote fat graft survival through facilitating vascularization, regulating collagen production, and inhibiting apoptosis. PRF can achieve the best promoting effect when the mixing ratio of PRF to fat is 1:10, which is recommended as the optimal ratio for clinical application.

Comparison of Conventional and Platelet-Rich Plasma-Assisted Fat Grafting: A Systematic Review and Meta-analysis

BACKGROUND

Autologous fat grafting (FG) is a popular technique for soft-tissue augmentation, but the fat survival rate is unpredictable. Platelet-rich plasma (PRP) has emerged as an adjuvant to enhance fat graft survival.

OBJECTIVES

This literature review and meta-analysis aimed to investigate the effect of PRP on the survival rate of fat grafting.

METHODS

A comprehensive systematic literature search was done to identify clinical studies on PRP and fat cotransplantation in PubMed, Cochrane Library, Web of Science, and EMBASE databases up to May 2020. The reference lists of selected articles were reviewed to identify any additional related articles. A meta-analysis was conducted to compare PRP + FG and conventional FG in terms of fat graft survival rate, patient satisfaction rate, and recovery time after surgery.

RESULTS

Eleven studies consisting of 1125 patients were analyzed. Patients were followed up from 3 to 24 months post-FG. The fat survival rate varied from 20.5% to 54.8% in FG alone and from 24.1% to 89.2% in the PRP + FG groups. The survival rate was significantly higher and recovery time was significantly lower in the PRP + FG group than in the FG alone group. However, there was no significant difference in the patient satisfaction rate between the groups.

CONCLUSIONS

This study demonstrates that PRP-enhanced fat transplantation has better efficacy than conventional fat grafting. Further studies are required to provide the optimum concentration of PRP and the long-term efficacy of the technique. There is not enough evidence to compare the rate of complications with PRP and fat cotransplantation and conventional fat grafting.

The Future of Fat Grafting

One of the earliest reported cases of autologous fat grafting (AFG) was by Neuber in 1893 and consisted of the transfer of small lobules of fat from the upper arm for cicatrical depression of the face. He advocated the use of smaller grafts, noting that pieces larger than the size of a bean would form cysts. In 1895, Czerny excised a lumbar lipoma and transplanted it to the chest for breast reconstruction. Since these early reports, the knowledge base around AFG has expanded exponentially, as illustrated by the other papers within this special topic. As we embark on the next phase of AFG in the clinical setting, there are several directions which are near-clinical translation. This paper discusses future directions in fat grafting that build on optimization of our current techniques as clinical indications expand, such as supplementing purified lipoaspirate and the associated regulatory burden, or deconstructing adipose tissue to selectively use adipose graft components for a variety of regenerative indications.

Comparison of the Effects of Repeated Applications of Platelet-Rich Plasma versus Platelet-Poor Plasma on Fat Graft Survival in Nude Mice

Autologous fat grafting has been widely used for soft tissue filling in plastic surgery. Platelet-rich plasma (PRP) could play a wide role in health and disease because of containing a variety of growth factors and cytokines. Although previous studies have described the positive effect of autologous PRP mixed with fat grafts, only minimal improvements in fat graft survival have been reported. The present study is aimed at comparing the effects of PRP and platelet-poor plasma (PPP) on the survival and quality of fat grafting. We built a 180-day nude mouse model implanted with a fat graft supplemented with PRP, PPP, or saline, respectively. The above reagents (PRP, PPP, or saline) were injected two additional times after the initial engraftment. The survival ratio of the fat grafts and the capillary density in the PRP group were significantly higher than those in the PPP group and the saline group (control group) at 15, 30, 90, and 180 days posttransplantation (P < 0.05). The survival ratio of the PPP group was higher than that of the saline group (P < 0.05), but the capillary density in the PPP group was not significantly different from that in the saline group at any time point (P > 0.05). We hence conclude that the repeated application of PRP or PPP three times can enhance the survival of fat grafts within 180 days. Moreover, the effect of PRP is superior to that of PPP.

Superparamagnetic Iron Oxide Particles (VSOPs) Show Genotoxic Effects but No Functional Impact on Human Adipose Tissue-Derived Stromal Cells (ASCs)

Adipose tissue-derived stromal cells (ASCs) represent a capable source for cell-based therapeutic approaches. For monitoring a cell-based application in vivo, magnetic resonance imaging (MRI) of cells labeled with iron oxide particles is a common method. It is the aim of the present study to analyze potential DNA damage, cytotoxicity and impairment of functional properties of human (h)ASCs after labeling with citrate-coated very small superparamagnetic iron oxide particles (VSOPs). Cytotoxic as well as genotoxic effects of the labeling procedure were measured in labeled and unlabeled hASCs using the MTT assay, comet assay and chromosomal aberration test. Trilineage differentiation was performed to evaluate an impairment of the differentiation potential due to the particles. Proliferation as well as migration capability were analyzed after the labeling procedure. Furthermore, the labeling of the hASCs was confirmed by Prussian blue staining, transmission electron microscopy (TEM) and high-resolution MRI. Below the concentration of 0.6 mM, which was used for the procedure, no evidence of genotoxic effects was found. At 0.6 mM, 1 mM as well as 1.5 mM, an increase in the number of chromosomal aberrations was determined. Cytotoxic effects were not observed at any concentration. Proliferation, migration capability and differentiation potential were also not affected by the procedure. Labeling with VSOPs is a useful labeling method for hASCs that does not affect their proliferation, migration and differentiation potential. Despite the absence of cytotoxicity, however, indications of genotoxic effects have been demonstrated.

Effects of Harvest Sites on Cryopreserved Adipose-Derived Stem Cells and ASC-Enriched Fat Grafts

BACKGROUND

Enrichment of adipose-derived stem cells (ASCs) with fat grafts has demonstrated benefit for graft retention and histologic appearance. There is no consensus on the optimal harvest site for adipose-derived stem cells. This study aimed to investigate the effects of harvest sites on the characteristics of cryopreserved adipose-derived stem cells and the graft retention of cell-assisted lipotransfer.

METHODS

Lipoaspirates were harvested from 18 healthy volunteers who underwent liposuctions for body contouring. Twenty milliliters of lipoaspirates was, respectively, obtained from four sites, including the upper limb, abdomen, waist, and thighs, by the Coleman technique. Adipose-derived stem cells were ex vivo cultured and cryopreserved for four weeks. The biological characteristics of ASCs from four harvest sites were analyzed: MSC surface markers, cell proliferation, migration ability, and multipotential differentiation. The fat grafts were co-implanted with ASCs from four harvest sites and injected subcutaneously in mice. The ASC-enriched fat grafts were analyzed three months after transplantation.

RESULTS

Cryopreserved ASCs from the abdomen and thighs maintained more significant cell proliferation, migration ability, and differentiation potential, compared with cells from the upper limb and waist. Moreover, we achieved better graft retention of cell-assisted fat grafts with cryopreserved ASC from the abdomen and thighs.

CONCLUSIONS

The harvest site of adipose tissue affects the cellular activity and differentiation potential of cryopreserved ASCs. Improved understanding of harvest sites for ASCs can optimize the outcomes of cell-assisted fat grafts. Fat grafts enriched with cryopreserved ASCs from the abdomen or thighs are the optimal choices.

LEVEL OF EVIDENCE V

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 .

Regenerative medicine approaches for the management of respiratory tract fistulas

Respiratory tract fistulas (or fistulae) are abnormal communications between the respiratory system and the digestive tract or the adjacent organs. The origin can be congenital or, more frequently, iatrogenic and the clinical presentation is heterogeneous. Respiratory tract fistulas can lead to severely reduced health-related quality of life and short survival. Therapy mainly relies on endoscopic surgical interventions but patients often require prolonged hospitalization and may develop complications. Therefore, more conservative regenerative medicine approaches, mainly based on lipotransfer, have also been investigated. Adipose tissue can be delivered either as unprocessed tissue, or after enzymatic treatment to derive the cellular stromal vascular fraction. In the current narrative review, we provide an overview of the main tissue/cell-based clinical studies for the management of various types of respiratory tract fistulas or injuries. Clinical experience is limited, as most of the studies were performed on a small number of patients. Albeit a conclusive proof of efficacy cannot be drawn, the reviewed studies suggest that grafting of adipose tissue-derived material may represent a minimally invasive and conservative treatment option, alternative to more aggressive surgical procedures. Knowledge on safety and tolerability acquired in prior studies can lead to the design of future, larger trials that may exploit innovative procedures for tissue processing to further improve the clinical outcome.

Autologous Fat Grafting for the Oral and Digital Complications of Systemic Sclerosis: Results of a Prospective Study

BACKGROUND

Systemic sclerosis is a connective tissue disease. Skin involvement of the mouth and hand may compromise function and quality of life. Autologous fat grafting has been described as a specific treatment of these clinical features. We report the results of our prospective study designed to treat and prevent skin complications in systemic sclerosis.

MATERIALS AND METHODS

We treated 25 patients with mouth and/or hand involvement (microstomia, xerostomia, skin sclerosis, Raynaud's phenomenon and long-lasting digital ulcers) with autologous fat grafting, according to the Coleman's technique, around the mouth and/or at the base of each finger. The surgical procedures were repeated in each patient every 6 months for a total of two or three times. Clinical data were collected before the first surgery and again 6 months after each surgical procedure. Pain, skin thickness, saliva production and disability were assessed with validated tests.

RESULTS

Overall we performed 63 autologous fat grafting sessions (either on the mouth, on the hands or on both anatomical areas). Results at 6 moths after the last session included improvement of xerostomia evaluated with a sialogram, reduction of the skin tension around the mouth and, in the hands, reduction of the Raynaud phenomenon as well as skin thickness. Pain was reduced while the perception of disability improved. Digital ulcers healed completely in 8/9 patients.

CONCLUSIONS

Our results confirm the efficacy and safety of autologous fat grafting for the treatment of skin complications and digital ulcers due to systemic sclerosis. In addition, the patients' subjective well-being improved. Level of evidence V 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 .

Ischemia-Like Stress Conditions Stimulate Trophic Activities of Adipose-Derived Stromal/Stem Cells

Adipose-derived stromal/stem cells (ASCs) have been shown to exert regenerative functions, which are mainly attributed to the secretion of trophic factors. Upon transplantation, ASCs are facing an ischemic environment characterized by oxygen and nutrient deprivation. However, current knowledge on the secretion capacity of ASCs under such conditions is limited. Thus, the present study focused on the secretory function of ASCs under glucose and oxygen deprivation as major components of ischemia. After exposure to glucose/oxygen deprivation, ASCs maintained distinct viability, but the metabolic activity was greatly reduced by glucose limitation. ASCs were able to secrete a broad panel of factors under glucose/oxygen deprivation as revealed by a cytokine antibody array. Quantification of selected factors by ELISA demonstrated that glucose deprivation in combination with hypoxia led to markedly higher secretion levels of the angiogenic and anti-apoptotic factors IL-6, VEGF, and stanniocalcin-1 as compared to the hypoxic condition alone. A conditioned medium of glucose/oxygen-deprived ASCs promoted the viability and tube formation of endothelial cells, and the proliferation and migration of fibroblasts. These findings indicate that ASCs are stimulated by ischemia-like stress conditions to secrete trophic factors and would be able to exert their beneficial function in an ischemic environment.

The application of platelet-rich plasma for skin graft enrichment: A meta-analysis

Existing evidence demonstrated that the role of platelet-rich plasma (PRP) in skin graft enrichment is uncertain. The aim of this study was to evaluate the efficacy and safety of PRP for skin graft. PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched for randomised controlled trials that compared outcomes of skin graft treated with PRP versus those treated with blank controls. The outcomes mainly included the rate of skin graft take, number of skin graft loss and haematoma formation, and complications. There were 11 studies involving a total of 910 cases of skin grafts. Compared with the control group, PRP group had a significantly higher rate of skin graft take (mean difference = 5.47%; 95% confidence interval [CI], 2.80%-8.14%; P < .0001), fewer number of skin graft loss (risk ratio [RR] = 0.26; 95% CI, 0.13-0.55; P = .0004) and fewer cases of haematoma formation (RR = 0.24; 95% CI, 0.11-0.54; P = .0006). There was no significant difference in the incidence of complications between two groups. This meta-analysis summarises current evidence and indicates that PRP is a safe and effective adjuvant for skin graft enrichment.