Supplementation of fat grafts with adipose-derived regenerative cells improves long-term graft retention. Ann Plast Surg. 2010;64:222-228. [PMID: 20098110 DOI: 10.1097/sap.0b013e31819ae05c]

Cool Fat, Hot Topic: A Systematic Review on Cryopreservation of Adipose Tissue

Autologous fat grafting is increasingly used in plastic, reconstructive, and esthetic surgery. Cryopreservation offers a promising solution for the long-term storage of adipose tissue, enabling multiple grafting sessions while minimizing patient discomfort associated with repeated liposuction for fat harvesting. This systematic review aims to analyze the current literature focusing on factors that influence the outcome of cryopreservation, including the use of cryoprotectants, the cooling and warming rate, the storage temperature, and the enrichment of cryopreserved fat grafts. A systematic search of the PubMed/MEDLINE database up to November 2024 was performed, including original preclinical and clinical studies written in English describing the cryopreservation of unprocessed or mechanically processed adipose tissue (macrofat, microfat, or nanofat). Eligible articles needed to describe the applied cryopreservation protocol, at least the storage temperature. Studies on cryopreservation of adipose-derived stem cells (ASCs), stromal vascular fraction, microvascular fragments, and other isolated components of adipose tissue were excluded. Data on cryoprotectants, cooling and warming rates, storage temperature, and eventual supplementation or enrichment of frozen fat were collected. Of the 679 records identified, 59 met the inclusion criteria. Adipose tissue cryopreservation at -80°C with a cryoprotectant, controlled slow cooling, and fast warming represented the most often applied protocol with encouraging outcomes in maintaining tissue survival and histological structure. Several studies indicated that the supplementation of frozen adipose tissue with ASCs improves tissue survival. Taken together, existing studies present diverse, and to some extent, conflicting results regarding cryopreservation protocols and their effects on adipose tissue viability. Hence, the ideal cryopreservation protocol for autologous fat remains to be established. Moreover, tailored protocols may be necessary for the cryopreservation of fat derivatives, such as nanofat.

Vascular Endothelial Growth Factor Expression of Adipose-Derived Stromal Cells and Adipocytes Initiated from Fat Aspirations

BACKGROUND

Fat grafting is frequently employed in aesthetic and reconstructive plastic surgery with a low complication rate. However, fat necrosis may occur in dependence of the mode of fat aspiration, processing of the tissue and graft size. Graft survival is critically dependent on the contained adipose-derived stromal cells (ADSCs), adipocyte precursors and their potential for vascular supply. This work investigated the potential role of the expression of vascular endothelial growth factor A (VEGF) and various cytokines by ADSCs and differentiated adipocytes as key factors of fat grafting.

METHODS

Adipokine expression of ADSCs and differentiated adipocytes were assessed using Proteome Profiler Arrays that detect 58 relevant proteins.

RESULTS

Collected fat grafts could be categorized according to their adipokine expression into VEGFhigh and VEGFlow ADSCs groups, the former exhibiting higher content of VEGF-related angiopoietin-like 2, nidogen-1/entactin, CCL2/MCP-1 and elevated expression of IGFBPs in association with a fourfold higher VEGF expression. Differentiation of ADSCs into adipocytes increased VEGF concentrations in VEGFlow ADSCs but not in ADSCs exhibiting initial high VEGF concentrations. The adipocytes revealed high expression of HGF, leptin, CCL2/MCP-1, nidogen-1/entactin, M-CSF but lower induction of angiopoietin-like 2.

CONCLUSION

Half of the ADSCs from fat grafts express high concentrations of VEGF and other adipokines that support angiogenesis and survival of this tissues following transfer. Differentiation of ADSClow cells to adipocytes may make up for the initially low VEGF expression, but this activation is 7-10 days delayed compared to the VEGFhigh ADSC cells and may fail to support angiogenesis from the beginning.

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 .

Autologous fat grafting auxiliary methods in craniofacial deformities: A systematic review and network meta-analysis

BACKGROUND

To increase autologous fat grafting (AFG) volume retention, current advancements focus on adding an auxiliary method to the process. This review aimed to address which auxiliary methods prove to be the best in terms of volume retention outcome.

METHODS

A comprehensive literature search was performed in five medical databases, including PubMed, Proquest, Scopus, CENTRAL, and ScienceDirect, until March 2024, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines.

RESULTS

Twenty-six studies were included in this review, and seven studies were included in the network meta-analysis. Reported auxiliary methods include stromal vascular fractions (SVFs) [12.20, 95% confidence intervals (CI) 0.04 to 24.35], adipose tissue-derived stem cells (ADSCs) (24.20, 95% CI 4.14 to 44.26), and platelet-rich plasma (PRP) [24.10, 95% CI -2.68 to 50.88]. When compared with the standard AFG approach, SVFs (p = 0.049) and ADSCs (p = 0.018) were more successful in retaining volume. However, PRP (p = 0.077) was not as effective. The comparison between auxiliary approaches, ADSCs vs PRP (p = 0.994), ADSCs vs SVFs (p = 0.271), and PRP vs SVF (p = 0.383), did not show any significant differences. Subgroup analysis revealed that the use of volumetric measuring methods has a substantial impact on the reported volume retention (p < 0.0001).

CONCLUSION

Enhanced volume retention can be attained with the utilization of SVF and ADSCs auxiliary methods in comparison to AFG, with or without PRP. Given the insignificant differences between SVF and ADSC, along with the greater complexity of the ADSC process, we recommend for the preferable use of SVF.

"SAVE"-Shock-Assisted Viable Extraction: A Minimally Manipulative Method of Processing Regenerative Cells for Clinical Use

Background

Extraction of adipose-derived stem cells (ASCs) from the stromal vascular fraction (SVF) has gained significant attention lately in the realm of regenerative medicine. However, finding highly efficient methods of extraction that also comply with the US regulations has prevented widespread clinical use.

Objectives

The objective of this study was to evaluate a novel ASC extraction device to quantify viable ASC extraction and processing efficiency.

Methods

SVF extracted from abdominal fat samples and processed using a novel shock-assisted viable extraction (SAVE) device was tested for stem-cell count and viability. Additionally, time required for processing was recorded.

Results

Twelve adipose samples were utilized for this study. After a mean time of 3 min, cell count yield ranged of 47,400 to 189,400 of viable regenerative cells per cc, with an average of 122,464 viable regenerative cells per cc.

Conclusions

SAVE is a novel fat-processing technique with high stem-cell extraction that shows promise from a regulatory, yield, time efficiency, and cost perspective.

Level of Evidence 5 Therapeutic

Effects of nanographene oxide on adipose-derived stem cell cryopreservation

Cryoinjury mitigation is key in cell cryopreservation. Here, we aimed to assess the effectiveness of nanographene oxide (nano-GO) for improving cryoprotectant agents (CPAs) in human adipose stem cell (hADSC) cryopreservation. For in vitro experiments, nano-GO (5 μg/mL) was added to the CPAs in the control, and passage (P) 2 hADSCs were collected and cryopreserved for around two weeks. We compared cytotoxicity, cell viability, immunophenotypes, proliferation, cell apoptosis, and tri-lineage differentiation. In vivo, studies used lipoaspirate to create non-enriched or hADSC-enriched fat tissues by combining it with PBS or hADSCs cryopreserved with the aforementioned CPAs. Each nude mouse received a 0.3 mL subcutaneous injection of the graft. At 12 weeks, the grafts were harvested. Histology, adipocyte-associated genes and protein, vascular density and angiogenic cytokines, macrophage infiltration, and inflammatory cytokines were analyzed. Nano-GO CPA contributed to increased cell viability, improved cell recovery, and lowered levels of early apoptosis. Nano GO at concentrations of 0.01-100 μg/mL caused no cytotoxicity to hADSCs. The absence of nano GOs in the intracellular compartments of the cells was confirmed by transmission electron microscopy. The fat grafts from the CPA-GO group showed more viable adipocytes and significantly increased angiogenesis compared to the PBS and CPA-C groups. Adding hADSCs from the CPA-GO group to the graft reduced macrophage infiltration and MCP-1 expression. Nano-GO plays an anti-apoptotic role in the cryopreservation of hADSCs, which could improve the survival of transplanted fat tissues, possibly via improved angiogenesis and lower inflammatory response in the transplanted adipose tissue.

An Evaluation of Autologous Fat Injection as a Treatment for Velopharyngeal Insufficiency: A Review and Integrated Data Analysis

BACKGROUND

Velopharyngeal insufficiency (VPI) is a condition characterized by incomplete separation of the oral and nasal cavities during speech production, thereby leading to speech abnormalities and audible nasal emissions. Subsequently, this adversely impacts communication and potentially interpersonal social interactions. Autologous fat grafting (AFG) to the velopharynx, a minimally invasive technique, aims to improve oronasal separation by providing bulk and advancing the posterior pharyngeal wall toward the soft palate. Despite its potential, the relative novelty of AFG in treating VPI has resulted in reporting of inconsistent indications, varied surgical techniques, and mixed outcomes across existing literature.

METHODS

This systemic review examined the evidence of AFG for VPI treatment over the past decade (2013-2023). A thorough search across five electronic databases yielded 233 studies, with 20 meeting the inclusion criteria (e.g., utilized fat injection as their selected VPI treatment, conducted study in human subjects, did not perform additional surgical procedure at time of fat injection). Selected studies encompassed patient and surgical intervention characteristics, perceptual speech assessment (PSA) scores, gap sizes, nasalance measurements, and complications.

RESULTS

The majority of patients had a prior cleft palate diagnosis (78.2%), in which nasoendoscopy was the prevalent method for visualizing the velopharyngeal port defect. Fat harvesting predominantly occurred from the abdomen (64.3%), with an average injection volume of 6.3 mL across studies. PSA and subjective gap size scores were consistently higher preoperatively than postoperatively. PSA score analysis from seven studies revealed significant and sustained improvements postoperatively. Gap size score analysis from four studies demonstrated similar preoperative and postoperative differences. Complications were reported in 17 studies, yielding a 2.7% summative complication rate among 594 cases.

CONCLUSIONS

Autologous fat grafting has emerged as a minimally invasive, safe, and effective treatment for mild to moderate VPI. However, challenges remain because of variability in patient selection criteria, diagnostic modalities, and outcome measurements. This review underscores the need for randomized control trials to directly compare AFG with standard-of-care surgical interventions, providing more conclusive evidence of its clinical efficacy.

Stem Cell Enriched Fat Grafts versus Autologous Fat Grafts in Reconstructive Surgery: Systematic Review and Meta-Analysis

OBJECTIVE

To compare the outcomes of stem cell-enrichment fat grafting (SCEFG) versus autologous fat grafting (AFG) for reconstructive purposes.

METHODS

A systematic review and meta-analysis was performed as per the preferred reporting items for systematic reviews and meta-analyses. Guidelines and a search of electronic information was conducted to identify all Randomised Controlled Trials (RCTs), case-control studies and cohort studies comparing the outcomes of SCEFG versus AFG. Volume retention, fat necrosis, cancer recurrence, redness and swelling, infection, and cysts were primary outcome measures. Secondary outcome measures included patient satisfaction post-surgery, scar assessment, operation time and number of fat grafting sessions. Fixed and random effects modelling were used for the analysis.

RESULTS

16 studies enrolling 686 subjects were selected. Significant differences between the SCEFG and AFG groups were seen in mean volume retention (standardised mean difference = 3.00, P < 0.0001) and the incidence of redness and swelling (Odds Ratio [OR] = 441, P = 0.003). No significant difference between the two groups in terms of fat necrosis (OR = 2.23, P = 0.26), cancer recurrence (OR = 1.39, P = 0.58), infection (OR = 0.30, P = 0.48) and cysts (OR = 0.88, P = 0.91). For secondary outcomes, both cohorts had similar results in patient satisfaction, scar assessment and number of fat grafting sessions. Operation time was longer for the intervention group.

CONCLUSIONS

SCEFG offers better outcomes when compared to AFG for reconstructive surgery as it improves the mean volume retention and does not worsen patient satisfaction and surgical complications except for self-limiting redness and swelling. Further clinical trials are recommended to support this argument and validate the use of SCEFG in clinical practice.

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 .

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 .

Injectable and Self-Adaptive Gel Scaffold Based on Heparin Microspheres for Adipogenesis of Human Adipose-Derived Stem Cells

An injectable and self-adaptive heparin microsphere-based cell scaffold was developed to achieve adipose regeneration. Simultaneously, the cell scaffold exhibited a dynamic architecture, self-regulated glucose levels, sustained insulin delivery, and steady viscoelastic properties for adipogenesis. The dynamic cell scaffold is cross-linked by the boronate-diol interaction among heparin-based microspheres, which have boronate and maltose groups. Because of the boronate-maltose ester bonds, the gelatinous complex would be partially dismantled and readily display glucose-sensitive performance by free glucose via competitive displacement. The dynamic cross-linking heparin microsphere scaffold can deliver the lipogenic drug insulin to enhance lipid filling, which has an impact on fat tissue enhancement. A 4-week in vitro cell culture demonstrated that the dynamic heparin microsphere-based cell scaffold, through loading with insulin, showed significantly higher efficiency in promoting ASC differentiation compared with traditional 3D culture methods. In vivo histological results further demonstrated that there was a significant increase in adipose in the proposed cell scaffold, which proved to be statistically significant compared with traditional biomaterials. Notable stain expression of the FABP4 and PPAR-γ genes was also observed in the dynamic cell scaffold containing insulin, which was more similar to natural fat.

Heterogeneous Cells as well as Adipose-Derived Stromal Cells in Stromal Vascular Fraction Contribute to Enhance Anabolic and Inhibit Catabolic Factors in Osteoarthritis

The stromal-vascular fraction (SVF), comprising heterogeneous cell populations and adipose-derived stromal cells (ADSCs), has therapeutic potential against osteoarthritis (OA); however, the underlying mechanism remains elusive. This study aimed to investigate the therapeutic effects of heterogeneous cells in rabbit SVF on rabbit chondrocytes. Rabbit SVF and ADSCs were autografted into knees at OA onset. The SVF (1 × 105) and low-dose ADSCs (lADSC; 1 × 104) groups adjusted for their stromal cell content were compared. Animals were euthanized 8 and 12 weeks after OA onset for macroscopic and histological analyses of OA progression and synovitis. Immunohistochemical and real-time polymerase chain reaction assessments were conducted. In vitro, immune-fluorescent double staining was performed for SVF to stain macrophages with F4/80, CD86(M1), and CD163(M2). OA progression was markedly suppressed, and synovitis was reduced in the SVF groups (OARSI histological score 8 W: 6.8 ± 0.75 vs. 3.8 ± 0.75, p = 0.001; 12 W: 8.8 ± 0.4 vs. 5.4 ± 0.49, p = 0.0002). The SVF groups had higher expression of collagen II and SOX9 in cartilage and TGF-β and IL-10 in the synovium, lower expression of MMP-13, and lower macrophage M1/M2 ratio than the lADSC groups. Immunofluorescent double staining revealed a markedly higher number of M2 than that of M1 macrophages in the SVF. The therapeutic effects of SVF on chondrocytes were superior than those of lADSCs, with enhanced anabolic and inhibited catabolic factors. Heterogeneous cells, mainly M2 macrophages in the SVF, enhanced growth factor secretion and chondrocyte-protective cytokines, thus benefiting chondrocytes and knee joint homeostasis. Overall, the SVF is a safe, relatively simple, and a useful treatment option for OA.

Self-assembled adipose-derived mesenchymal stem cells as an extracellular matrix component- and growth factor-enriched filler

The clinical application of mesenchymal stem cells (MSCs) is attracting attention due to their excellent safety, convenient acquisition, multipotency, and trophic activity. The clinical effectiveness of transplanted MSCs is well-known in regenerative and immunomodulatory medicine, but there is a demand for their improved viability and regenerative function after transplantation. In this study, we isolated MSCs from adipose tissue from three human donors and generated uniformly sized MSC spheroids (∼100 µm in diameter) called microblocks (MiBs) for dermal reconstitution. The viability and MSC marker expression of MSCs in MiBs were similar to those of monolayer MSCs. Compared with monolayer MSCs, MiBs produced more extracellular matrix (ECM) components, including type I collagen, fibronectin, and hyaluronic acid, and growth factors such as vascular endothelial growth factor and hepatocyte growth factor. Subcutaneously injected MiBs showed skin volume retaining capacity in mice. These results indicate that MiBs could be applied as regenerative medicine for skin conditions such as atrophic scar by having high ECM and bioactive factor expression.

Stem Cell-Enriched Hybrid Breast Reconstruction Reduces Risk for Capsular Contracture in a Hybrid Breast Model

BACKGROUND

Hybrid breast reconstruction (HBR) combines silicone implants with fat grafting to improve implant coverage, treating local tissue deficiencies and leading to a more natural breast appearance. Recent data also indicated less capsular contracture after HBR. The authors developed a novel technique and animal model of cell-assisted (CA) HBR to illuminate its effects on capsular contracture.

METHODS

Animals received silicone implants in a dorsal submuscular pocket. Although animals of the HBR group received fat grafting around the implant without stem cell enrichment, rats of the CA-HBR1 and the CA-HBR2 groups received stem cell-enriched fat grafting with 2 × 10 6 and 4 × 10 6 adipose-derived stem cells immediately after implant insertion. On day 60, animals underwent sonography and elastography imaging and were euthanized, and outcome analysis was performed by means of histology, immunohistochemistry, chemical collagen quantification, and gene expression analysis.

RESULTS

With this novel technique, long-term survival of adipose-derived stem cells within the implant pocket was demonstrated after 60 days after implant insertion. CA-HBR led to significantly reduced thickness and collagen density of capsular contractures. In addition, CA-HBR resulted in reduced fibrotic responses with less occurrence of collagen type I and transforming growth factor-β in capsule tissue. Moreover, the addition of stem cells suppressed fibrotic and inflammatory responses on a genetic level with significant underexpression of collagen type I and transforming growth factor-β1.

CONCLUSIONS

With this new technique and animal model, the authors observed a preventive effect on capsular contracture substantiating the basis of clinical outcomes of HBR. The authors propose that the addition of stem cells to HBR might booster its beneficial results.

CLINICAL RELEVANCE STATEMENT

Stem cell-enriched fat grafting around silicone implants may reduce the risk for capsular contracture after silicone breast implantation. While fat grafting alone already shows beneficial effects, the addition of stem cells to the fat graft can potentiate this effect.

Autologous fat transfer for orbital volume augmentation in sockets with small nonseeing eyes

OBJECTIVE

End-stage ocular diseases usually end up with atrophic bulbi or phthisis bulbi leading to orbital volume loss which needs to be addressed. We studied the use of autologous fat for volume augmentation of the orbit because it is minimally invasive and allows early rehabilitation with the use of an artificial eye.

DESIGN

It was a prospective, interventional study.

METHODS

A total of 14 eyes of 14 patients with atrophic bulbi with shrinkage or phthisis bulbi with no perception of light (PL) and aged older than 18 years were included for the study purpose. Painful or inflamed eyes or suspected intraocular tumors were excluded. An autologous fat graft was obtained from the lower abdomen or buttocks and injected into the retrobulbar space using a 20-gauge cannula after adequate peribulbar anesthesia. Outcomes measures were patient satisfaction, change in Hertel's exophthalmometry, vertical and horizontal palpebral aperture, and socket volume.

RESULTS

Hertel exophthalmometry showed a significant improvement both with and without an artificial eye from 14.92 ± 2.3 mm to 16.71 ± 1.94 mm (p-value 0.003 without an artificial eye). The vertical palpebral aperture also showed a significant improvement from 5 ± 1.70 mm to 6.71 ± 1.58 mm (p-value < 0.001). There was a significant reduction in the socket volume from 1.22 ml to 0.39 ml (p-value < 0.001). No local or donor site complications were seen.

CONCLUSIONS

Autologous fat transfer is a minimally invasive, safe, and effective procedure for orbital volume augmentation in small, nonseeing eyes. The short-term outcome of our study was good in most patients and can be considered for such patients.

Fat Graft Retention: Adipose Tissue, Adipose-Derived Stem Cells, and Aging

SUMMARY

Over the past 30 years, there has been a dramatic increase in the use of autologous fat grafting for soft-tissue augmentation and to improve facial skin quality. Several studies have highlighted the impact of aging on adipose tissue, leading to a decrease of adipose tissue volume and preadipocyte proliferation and increase of fibrosis. Recently, there has been a rising interest in adipose tissue components, including adipose-derived stem/stromal cells (ASCs) because of their regenerative potential, including inflammation, fibrosis, and vascularization modulation. Because of their differentiation potential and paracrine function, ASCs have been largely used for fat grafting procedures, as they are described to be a key component in fat graft survival. However, many parameters as surgical procedures or adipose tissue biology could change clinical outcomes. Variation on fat grafting methods have led to numerous inconsistent clinical outcomes. Donor-to-donor variation could also be imputed to ASCs, tissue inflammatory state, or tissue origin. In this review, the authors aim to analyze (1) the parameters involved in graft survival, and (2) the effect of aging on adipose tissue components, especially ASCs, that could lead to a decrease of skin regeneration and fat graft retention.

CLINICAL RELEVANCE STATEMENT

This review aims to enlighten surgeons about known parameters that could play a role in fat graft survival. ASCs and their potential mechanism of action in regenerative medicine are more specifically described.

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.

MiRNA regulated therapeutic potential of the stromal vascular fraction: Current clinical applications - A systematic review

Introduction

The stromal vascular fraction (SVF) is a heterogeneous population of cells that, interacting with each other, can affect the processes of regeneration, angiogenesis, and immunomodulation. Over the past 20 years, there has been a trend towards an increase in the number of clinical studies on the therapeutic use of SVF. MicroRNAs (miRNAs) are also important regulators of cellular function and they have been shown to be involved in SVF cellular component function. The purpose of this study was to analyze existing clinical studies on the therapeutic use of SVF including the role of miRNAs in the regulation of the function of the cellular component of SVF as an anti-inflammatory, pro-angiogenic and cell differentiation activity.

Methods

The search strategy was to use material from the clinicaltrials.gov website, which focused on the key term "Stromal vascular fraction", and the inclusion and exclusion criteria were divided into two stages.

Results

By August 2022, there were 149 registered clinical trials. Most studies belong to either Phase 1-2 (49.37%), Phase 1 (25.32%) or Phase 2 (22.78%). Most of them focused in the fields of traumatology, neurology/neurosurgery, endocrinology, vascular surgery, and immunology. However, only 8 clinical trials had published results. All of clinical trials have similar preparation methods and 8 clinical trials have positive results with no serious adverse effects.

Conclusions

There appears to be a wide potential for the clinical use of SVF without reports of serious side effects. Many preclinical and clinical studies are currently underway on the use of SVF, and their future results will help to further explore their therapeutic potential. Nevertheless, there are not many studies on the role of miRNAs in the SVF microenvironment; however, this topic is very important for further study of the clinical application of SVF, including safety, in various human diseases.

Bcl-2 modified adipose-derived stem cells improve the retention of fat graft

In cell-assisted lipotransfer, adipose-derived stem cells play a crucial role in enhancing fat graft retention. In vitro, human adipose-derived stem cells were modified with Bcl-2 gene. In vivo, aspirated fat was mixed with the Bcl-2-modified adipose-derived stem cells and then transplanted subcutaneously into nude mice. The retention of fat graft was evaluated. The surviving Bcl-2-modified adipose-derived stem cells were tracked after transplantation. Capillary density was quantified after transplantation. Transplantation with Bcl-2-modified adipose-derived stem cells enhanced fat graft retention by 49% and 114% at 6 weeks compared with the Fat + vector-modified adipose-derived stem cell group and Fat-only group, respectively. Transplants from the Fat + Bcl-2-modified adipose-derived stem cell group had significantly more intact adipocytes and lower levels of fat necrosis and fibrosis at 6 weeks. The survival of Bcl-2-modified adipose-derived stem cells increased by 33% at 3 weeks and 54% at 6 weeks, respectively, compared with vector-modified adipose-derived stem cells. The capillary density was 24% higher in Fat + Bcl-2-modified adipose-derived stem cell group than in Fat + vector-modified adipose-derived stem cell group or 60% higher than in Fat-only group at 3 weeks.

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.

Mechanical Stress Improves Fat Graft Survival by Promoting Adipose-Derived Stem Cells Proliferation

Cell-assisted lipotransfer (CAL), defined as co-transplantation of aspirated fat with enrichment of adipose-derived stem cells (ASCs), is a novel technique for cosmetic and reconstructive surgery to overcome the low survival rate of traditional fat grafting. However, clinically approved techniques for increasing the potency of ASCs in CAL have not been developed yet. As a more clinically applicable method, we used mechanical stress to reinforce the potency of ASCs. Mechanical stress was applied to the inguinal fat pad by needling. Morphological and cellular changes in adipose tissues were examined by flow cytometric analysis 1, 3, 5, and 7 days after the procedure. The proliferation and adipogenesis potencies of ASCs were evaluated. CAL with ASCs treated with mechanical stress or sham control were performed, and engraftment was determined at 4 weeks post-operation. Flow cytometry analysis revealed that mechanical stress significantly increased the number as well as the frequency of ASC proliferation in fat. Proliferation assays and adipocyte-specific marker gene analysis revealed that mechanical stress promoted proliferation potential but did not affect the differentiation capacity of ASCs. Moreover, CAL with cells derived from mechanical stress-treated fat increased the engraftment. Our results indicate that mechanical stress may be a simple method for improving the efficacy of CAL by enhancing the proliferation potency of ASCs.

Human Adipose Mesenchymal Stromal/Stem Cells Improve Fat Transplantation Performance

The resorption rate of autologous fat transfer (AFT) is 40–60% of the implanted tissue, requiring new surgical strategies for tissue reconstruction. We previously demonstrated in a rabbit model that AFT may be empowered by adipose-derived mesenchymal stromal/stem cells (AD-MSCs), which improve graft persistence by exerting proangiogenic/anti-inflammatory effects. However, their fate after implantation requires more investigation. We report a xenograft model of adipose tissue engineering in which NOD/SCID mice underwent AFT with/without human autologous AD-MSCs and were monitored for 180 days (d). The effect of AD-MSCs on AFT grafting was also monitored by evaluating the expression of CD31 and F4/80 markers. Green fluorescent protein-positive AD-MSCs (AD-MSC-GFP) were detected in fibroblastoid cells 7 days after transplantation and in mature adipocytes at 60 days, indicating both persistence and differentiation of the implanted cells. This evidence also correlated with the persistence of a higher graft weight in AFT-AD-MSC compared to AFT alone treated mice. An observation up to 180 d revealed a lower resorption rate and reduced lipidic cyst formation in the AFT-AD-MSC group, suggesting a long-term action of AD-MSCs in support of AFT performance and an anti-inflammatory/proangiogenic activity. Together, these data indicate the protective role of adipose progenitors in autologous AFT tissue resorption.

In Vitro Study on the Biological Characteristics of Adipose-Derived Stem Cells from Liposuction Area in Patients with Progressive Hemifacial Atrophy

OBJECTIVE

In this study, we investigate the biological characteristics of ADSCs from the liposuction area in patients with hemifacial atrophy in vitro.

METHODS

ADSCs were respectively extracted from the donor site of patients with hemifacial atrophy and healthy ones. ADSCs of two groups were respectively tested for proliferation ability, phenotype, multipotency, migration ability, self-repair ability, apoptosis, and autophagy. Exosomes extracted from the supernatant of two groups were detected by NTA particle size, electron microscopy (TEM), and WB for CD63 and TSG10, respectively.

RESULTS

CCK-8 showed a statistically less increase in cell proliferation in PHA-ADSCs after the sixth day. ADSCs in both groups had typical phenotypes and multidirectional abilities. PHA-ADSCs exhibited weaker droplet formation. The cell migration ability in PHA-ADSCs was weaker tested by Transwell assay. The live/dead proportion calculated by ImageJ following calcein-AM/PI double staining revealed live cells in PHA-ADSCs was 46.11% compared with 54.21% in NORM-ADSCs after OGD treatment. A significant down-regulation of ATG7 and ATG12 and a higher percentage of apoptosis were found in PHA-ADSCs. A significant up-regulation of BAX occurred in PHA-ADSCs.ARPC5 expression in the PHA group was extremely distinct down-regulated.CDKN1A and CDKN2A expression in the PHA group was significantly up-regulated.WB analyses confirmed that both groups' ADSCs-Exosomes surface markers CD63 and TSG101 were positively expressed but varied significantly.

CONCLUSIONS

PHA-ADSCs exhibited a poorer proliferation ability, higher apoptosis percentage, weaker lipid droplets formation, weaker cell migration, poorer intolerance to OGD, aging earlier, and weaker self-renewal and repairability.PHA-ADSCs-Exosomes showed low expressions of CD63 and TSG101.This study provides strong evidence that the addition of exosomes with specific cytokines can improve the fat survival rate after fat filling in patients with hemifacial atrophy.

NO LEVEL ASSIGNED

This journal requires that authors 42 assign a level of evidence to each submission to which 43 Evidence-Based Medicine rankings are applicable. This 44 excludes Review Articles, Book Reviews, and manuscripts 45 that concern Basic Science, Animal Studies, Cadaver 46 Studies, and Experimental Studies. For a full description of 47 these Evidence-Based Medicine ratings, please refer to the 48 Table of Contents or the online Instructions to Authors 49 https://www.springer.com/00266 .

Hormone Therapy: A Potential Risk Factor Affecting Survival and Functional Restoration of Transplanted Lymph Nodes

Background: Transplantation of lymph nodes (LNs) is an increasingly popular option for treating lymphedema. Increasing evidence indicates an intrinsic correlation between estrogen signaling and the lymphatic system. We explored the effects of 17β estradiol and antiestrogen treatment (tamoxifen) on the survival and functional restoration of transplanted popliteal lymph nodes (PLNs).

Methods: A total of forty-eight ovariectomized mice were divided into three groups of 16: OVX + E2 (treated with 17β-estradiol), OVX + TMX (treated with tamoxifen), and OVX (control; treated with olive oil as a solvent). After 2 weeks, PLNs were transplanted. Then, reconnections of lymphatic vessels were observed, and the morphology and survival of transplanted PLNs were evaluated 4 weeks after transplantation. T cells, B cells, lymphatic vessels, and high endothelial venules (HEVs) were subjected to immunofluorescence staining or immunohistochemical staining and quantified.

Results: The percentage of lymphatic reconnections was 93.75% in the OVX + E2 group, 68.75% in the OVX + TMX group, and 75% in the OVX group. Surviving PLNs were observed in 16 of 16 in the OVX + E2 group, seven of 16 in the OVX + TMX group, and 13 of 16 in the OVX group. The mean size of PLNs in the largest cross section of the OVX + TMX group was significantly lower than that in the other groups. The distributions of B cells and T cells in surviving PLNs were similar to those in normal LNs. The ratio of dilated HEVs/total HEVs and density of lymphatic vessels in the OVX + E2 group were the highest among the three groups, whereas the lowest ratio and density were observed in the OVX + TMX group.

Conclusion: Tamoxifen treatment might lead to cellular loss of transplanted LNs and interfere with the structural reconstruction and functional restoration, thereby inhibiting the survival of transplanted PLNs. Estrogen treatment facilitated the maintenance and regeneration of functional HEVs as well as lymphangiogenesis.

LRG-1 promotes fat graft survival through the RAB31-mediated inhibition of hypoxia-induced apoptosis

Autologous adipose tissue is an ideal soft tissue filling material, and its biocompatibility is better than that of artificial tissue substitutes, foreign bodies and heterogeneous materials. Although autologous fat transplantation has many advantages, the low retention rate of adipose tissue limits its clinical application. Here, we identified a secretory glycoprotein, leucine‐rich‐alpha‐2‐glycoprotein 1 (LRG‐1), that could promote fat graft survival through RAB31‐mediated inhibition of hypoxia‐induced apoptosis. We showed that LRG‐1 injection significantly increased the maintenance of fat volume and weight compared with the control. In addition, higher fat integrity, more viable adipocytes and fewer apoptotic cells were observed in the LRG‐1‐treated groups. Furthermore, we discovered that LRG‐1 could reduce the ADSC apoptosis induced by hypoxic conditions. The mechanism underlying the LRG‐1‐mediated suppression of the ADSC apoptosis induced by hypoxia was mediated by the upregulation of RAB31 expression. Using LRG‐1 for fat grafts may prove to be clinically successful for increasing the retention rate of transplanted fat.

Adipose-derived stem cell spheroids are superior to single-cell suspensions to improve fat autograft long-term survival

Autologous fat transplantation is a widely used procedure for surgical reconstruction of tissues. The resorption rate of this transplantation remains high and unpredictable, reinforcing the need of adjuvant treatments that increase the long‐term stability of grafts. Adipose‐derived stem cells (ASC) introduced as single cells in fat has been shown clinically to reduce the resorption of fat grafts. On the other hand, the formulation of ASC into cell spheroids results in the enhancement of their regenerative potential. In this study, we developed a novel method to produce highly homogeneous ASC spheroids and characterized their features and efficacy on fat transplantation. Spheroids conserved ASC markers and multipotency. A regenerative gene expression profile was maintained, and genes linked to autophagy were upregulated whereas proliferation was decreased. Their secreted proteome was enriched in comparison with single‐cell ASC suspension. Addition of spheroids to fat graft in an animal model of transplantation resulted in a better graft long‐term stability when compared to single ASC suspension. In conclusion, we provide a novel method to manufacture homogenous ASC spheroids. These ASC spheroids are superior to ASC in single‐cell suspension to improve the stability of fat transplants, reinforcing their potential in reconstructive surgery.

Autologous Fat Grafting - A Step Forward in Wound Management

Autologous fat grafting (AFG) is an emerging therapeutic option for wounds that are not ready for grafting. The regenerative potential of autologous fat lies in the adipose derived stem cells (ADSCs) contained within the stromal vascular fraction (SVF), which are capable of differentiating into multiple cell lineages. However to date, there has been no comprehensive evaluation of its efficacy in acute complicated wounds. This study aims to critically evaluate the efficacy and safety of AFG in cutaneous wound healing. Materials and Methods: This prospective, quasi experimental study was conducted in the Department Of Plastic Surgery, SIMS, Lahore, between June 2020 and June 2021. Thirty patients with pale granulation, not ready for grafting with no vital structure exposed were included in the study after detailed history, examination and were photographed pre and postoperatively. The procedure was performed under local anaesthesia. 40 to 80 ml fat was harvested from lower abdomen and after emulsification, placed over the wound wrapped in sufra tulle dressing. The dressing was changed on third postoperative day and outcome was assessed on clinical grounds. Results: Thirty patients (M:F Ratio 1.75:1) with mean age 30 years (Range 13-45 years) were included in this study with post traumatic (n = 23) and post infective (n = 7). Of 27 patients who completed their follow up, all had healthy granulation tissue which was later on grafted. Mean number of fat dressing sessions were 2 (Range 1-3). Conclusion: Autologous fat grafting has shown promising results for cutaneous wounds without any unacceptably high complication rates reported so far. Randomised controlled trials should be done on a larger scale to prove its efficacy in the management of complicated wounds.

Chondrogenic Characteristics of Auricular Chondrocytes Cocultured With Adipose-Derived Stem Cells are Superior to Stromal Vascular Fraction of Adipose Tissue

ABSTRACT

Reconstruction of craniofacial cartilage defects is among the most challenging operations in facial plastic surgery. The co-culture system of partial replacement of chondrocytes by stem cells has been confirmed effective in the repair of cartilaginous defects. The aim of this study is to compare chondrogenic properties of expanded adipose-derived stem cells (ADSCs) and stromal vascular fraction (SVF), including ADSCs/SVF monoculture and coculture with rabbit auricular chondrocytes (ACs). Analysis of morphology, histology, real-time polymerase chain reaction and glycosaminoglycans (GAG) quantification were performed to characterize the chondrogenesis of pellets. The triple differentiation potential of ADSCs had been confirmed. Further, using flow cytometry, the authors demonstrated that ADSCs and SVF have different characteristics in cell surface markers, and ADSCs are more enriched in cells from the mesenchymal lineage than SVF. GAG production of ADSCs is significantly higher than that of SVF in pellet monoculture, and pellet coculture of ADSCs and ACs are better in depositing cartilage matrix than the mixture of SVF and ACs. Our study suggests that ADSCs may be more suitable seed cells for craniofacial cartilage defect or deformity repair.

Facilitatory effects of artificial nerve filled with adipose-derived stem cell sheets on peripheral nerve regeneration: An experimental study

BACKGROUND

We evaluated how artificial nerves filled with adipose-derived stem cell (ADSC) sheets could facilitate peripheral nerve regeneration.

METHODS

We prepared ADSC sheets following previously described protocols. We transected the sciatic nerve in 12-week-old Wistar rats, fixed the nerve ends to the artificial conduit, and prepared three groups: (1) conduits alone (control group); (2) conduits filled with ADSCs (ADSCs group), and (3) conduits filled with ADSC sheets (ADSC sheet group). We assessed the subjects 4 and 12 weeks post-transplantation (n = 24). We investigated βIII-tubulin and anti-S100 expression at 4 and 12 weeks post-transplantation, in longitudinal- and cross-sections of the central portion in the regenerated tissues. The vascular endothelial growth factor A (VEGFA) and neuregulin-1 expressions were analyzed using real-time reverse-transcription polymerase chain reaction (real-time RT-PCR). We evaluated the tibialis anterior muscle wet weight (affected/healthy sides, %) and sciatic function index (SFI) 12 weeks post-transplantation.

RESULTS

The ADSC sheet group comprised more S100-positive cells than the other groups. The regenerated axon length in the ADSC sheet group was markedly the longest among the studied groups. The immunostaining revealed a positive area in the regenerated tissue center in all groups, tending to be the largest in the ADSC sheet group. The muscle wet weight indicated that the ADSC sheet group exhibited significantly higher weight than the control. The mean SFI showed that the ADSC sheet group exhibited significantly better results than the control. The VEGFA expression was higher both in the ADSC and the ADSC sheet group than in the control. The neuregulin-1 expression was higher both in the ADSC and the ADSC sheet group than in the control.

CONCLUSIONS

The ADSC sheets could potentially support transplanting an adequate number of ADSCs at the target site. Compared with the conventional method of attaching ADSCs, the use of ADSC sheets promotes accelerated nerve regeneration.

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.

Hybrid Implant and Grafted Fat Breast Augmentation: Designing the Pathway to a Future With Breasts Free of Silicone Breast Implants

BACKGROUND

Fat grafting in breast augmentation surgery is becoming increasingly popular, allowing surgeons to fill the gaps that implant augmentation alone cannot. However, one of the current issues surrounding fat grafting is the lack of standardization.

OBJECTIVES

The objective of this study was to validate and summarize expert-based advice to help plastic surgeons better understand the benefits of utilizing fat grating to reduce implant size in their surgical planning.

METHODS

This was a prospective study of fat grafting in 56 patients who underwent fat transfer together with silicone breast implants. A 3-dimensional planning system was used to plan the procedure and also to analyze the fat retention and resorption rates. Pictures served as a basis for a questionnaire in which both patients and physicians were asked to rate their satisfaction.

RESULTS

Patients reported a satisfaction rate of "excellent" in 83.3% of cases and "good" in 16.7%. Physician satisfaction was rated as "excellent" in 84.5% of cases, "good" in 13.3%, and "fair" in 4.2% of cases. The mean fat volume grafted per breast was 113.63 mL. The mean absorption rate was 4.53%.

CONCLUSIONS

The procedure presented consistent and reproducible results. Hybrid breast augmentation can help design a pathway for a future with breasts free of silicone. This information is particularly relevant for women who have their first breast augmentation at an early age and will probably have 2 to 5 additional surgeries in their lifetime due to the nature of current silicone breast technology.

LEVEL OF EVIDENCE: 4

ADSC-Based Cell Therapies for Musculoskeletal Disorders: A Review of Recent Clinical Trials

Recently published clinical trials involving the use of adipose-derived stem cells (ADSCs) indicated that approximately one-third of the studies were conducted on musculoskeletal disorders (MSD). MSD refers to a wide range of degenerative conditions of joints, bones, and muscles, and these conditions are the most common causes of chronic disability worldwide, being a major burden to the society. Conventional treatment modalities for MSD are not sufficient to correct the underlying structural abnormalities. Hence, ADSC-based cell therapies are being tested as a form of alternative, yet more effective, therapies in the management of MSDs. Therefore, in this review, MSDs subjected to the ADSC-based therapy were further categorized as arthritis, craniomaxillofacial defects, tendon/ligament related disorders, and spine disorders, and their brief characterization as well as the corresponding conventional therapeutic approaches with possible mechanisms with which ADSCs produce regenerative effects in disease-specific microenvironments were discussed to provide an overview of under which circumstances and on what bases the ADSC-based cell therapy was implemented. Providing an overview of the current status of ADSC-based cell therapy on MSDs can help to develop better and optimized strategies of ADSC-based therapeutics for MSDs as well as help to find novel clinical applications of ADSCs in the near future.

The Effects of Lipoaspirate-Derived Fibrous Tissue on Survival Quality and Mechanical Property of Fat Grafts

BACKGROUND

Fibrous connective tissue (referred to as fiber) in lipoaspirates would be discarded before lipotransfer in case of cannula blockage. However, the fiber contains extracellular matrix which provide structure support and is rich in stromal vascular fractions (SVFs). Removal of the fiber might theoretically affect the survival quality and mechanical properties of fat grafts. But there is few evidence in vivo and vitro about how the fiber affects the fat grafts.

OBJECTIVE

To assess the effect of fibers on the survival quality and mechanical property of fat grafts.

METHODS

The SVFs in both fat and fiber were obtained by collagenase digestion for cells counting and comparison. Three groups were designed according to the different proportions of fat and fiber: the fat group (100% fat), the mixed group (50% fat, 50% fiber in volume ratio), and the fiber group (100% fiber). Three groups of grafts were transplanted in vivo to evaluate the differences in volume retention rate, histological characteristics and mechanical properties.

RESULTS

The amount of SVF cells in fibers (3.47 ± 1.49 × 104 cells/mL) was significantly lower than that in fat (12.3 ± 4.95 × 104 cells/mL) (P < 0.05). Grafts in the mixed group and the fiber group showed an increase of volume retention at week 4, but the fiber content showed no significant effects on the volume retention of grafts in three groups at week 12. Elasticity modulus of grafts in the fat group was higher than that in the fiber group and the mixed group at week 4 and 8, the fiber content showed no significant effects on the elasticity modulus of grafts in three groups at week 12. The addition of the fiber reduced the inflammation, cysts, fibrosis, and capillaries density of the grafts.

CONCLUSIONS

There were few SVF cells in the fiber. When it was mixed with fat in different proportions and transplanted in vivo, the content of fiber showed no significantly different effects on the long-term volume retention and mechanical property of fat grafts. Due to the risk of blockage, it is recommended to discard the fiber in lipoaspirates.

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.

Innovative method of alopecia treatment by autologous adipose-derived SVF

Background

Alopecia refers to a condition developed by gradual reduction of hair loss by various abnormal causes such as endocrine system, genetic factors, and stress. Stromal vascular fraction (SVF) isolated from the fat is one of the latest innovative solutions in the field of regeneration therapy. We focused on presenting effectiveness of clinical cases to improve AGA through transplantation of autologous SVF into the scalp.

Objective

To confirm the efficacy of the autologous SVF usage to the patients with AGA.

Methods

Nine patients (age range 43–64 years; 4 men, grade IV to V and 5 women, grade I to III), who are suffering from androgenic alopecia (AGA), were treated with single transplantation of autologous SVF in the upper scalp. Autologous SVF was isolated and characterized prior to the injection of live 7–9 × 10⁶ cells into the patients’ treatment site. The hair loss improvement effect was assessed by three test criteria: hair skin quality, hair thickness and hair density 3 and 6 months after post-injection compared to pre-injection status.

Results

Hair density of SVF-treated side was significantly increased after 3 and 6 months of transplantation compared to non-treated side (P = 0.01 and P = 0.009 per each). And significant improvement in the score of the keratin on the scalp was seen in the injected area as compared to the non-injected area 6 months after transplantation (P = 0.032). Although thickness increase was observed at 3 and 6 months after transplantation, there was no statistical significance (P = 0.142 and 0.155, respectively).

Conclusions

One transplantation of autologous SVF for the AGA patients, hair density and score for the keratin were significantly increased within 6 months. This study shows that SVF is a very effective way to treat hair loss and most of subjects are satisfied with the result after treatment.

Effects of radiation and chemotherapy on adipose stem cells: Implications for use in fat grafting in cancer patients

Autologous fat transplantation is a versatile tool in reconstructive surgery. Adipose-derived stem cells (ASCs) increase survival of fat grafts and thus are increasingly used for breast reconstruction in breast cancer patients. However, radiation and/or chemotherapy have been proposed to inhibit soft tissue regeneration in wound healing thus suggesting alteration in stem cell pathways. Therefore, elucidating effects of radiation and chemotherapy on ASCs is critical if one desires to enhance the survival of fat grafts in patients. This review outlines our work evaluating the function and recoverability of ASCs from radiation or chemotherapy patients, focusing specifically on their availability as a source of autologous stem cells for fat grafting and breast reconstruction in cancer patients. Even though evidence suggests radiation and chemotherapy negatively influence ASCs at the cellular level, the efficiency of the isolation and differentiation capacity did not appear influenced in patients after receiving chemotherapy treatment, although fat from radiated patients exhibited significantly altered ASC differentiation into endothelial-like cells. Further, the in vitro growth rates of patient’s ASCs do not differ significantly before or after treatment. Taken together, these studies suggest ASCs as an important new tool for grafting and reconstruction even when radiation and chemotherapy treatment are involved.

Plasma rich in growth factors (PRGF -ENDORET®) to rescue necrotized orbital dermis-fat grafts

PURPOSE

We report on the clinical course of three patients treated with topical plasma rich in growth factors (PRGF) to rescue dermal-fat grafts (DFG) with graft ulceration (GU).

MATERIALS AND METHODS

A retrospective, case-series study of three patients diagnosed with GU in DFG and treated with PRGF. Drops were applied four times per day and treatment was maintained until the GU resolved. Data were collected from medical records and anterior segment photos.

RESULTS

All patients showed a favorable response to topical PRGF having accomplished full resolution of the GU within a mean of 30 days of treatment (range: 21-35 days). During the full extent of follow-up, no side-effects, signs of rejection or necrosis were reported and every patient was pleased with the final aesthetic result.

CONCLUSION

Our results suggest that PRGF could be an effective treatment for dermal graft ulceration in patients who underwent DFG surgery/implantation, mainly due to its low morbidity when compared to traditional procedures.

A Novel Fat Making Strategy With Adipose-Derived Progenitor Cell-Enriched Fat Improves Fat Graft Survival

BACKGROUND

A low survival rate is one of the main challenges in fat grafting.

OBJECTIVES

This study aimed to evaluate whether microfat obtained by a novel strategy promoted the survival and retention of fat grafts.

METHODS

A 5-mm-diameter blunt tip cannula with large side holes (~30 mm2/hole) was used to obtain macrofat. A novel strategy based on a newly invented extracorporeal cutting device was then used to cut the macrofat into microfat, which was named adipose-derived progenitor cell enrichment fat (AER fat); Coleman fat was used as the control. Aliquots (0.5 mL) of both types of fat were transplanted into 10 nude mice and analyzed 10 weeks later. Western blotting, flow cytometry, and immunofluorescence were performed to assess the AER fat characteristics and underlying mechanisms.

RESULTS

The retention rate of fat grafts in AER fat-treated animals was significantly higher than that in the Coleman group (mean [standard deviation] 54.6% [13%] vs 34.8% [9%]; P < 0.05) after 10 weeks. AER fat contained more dipeptidyl peptidase-4-expressing progenitor cells (3.3 [0.61] × 103 vs 2.0 [0.46] × 103 cells/mL; P < 0.05), adipose-derived plastic-adherent cells (6.0 [1.10] × 104 vs 2.6 [0.17] × 104 cells/mL; P < 0.001), and viable adipocytes than Coleman fat. Moreover, histologic analysis showed that AER fat grafts had better histologic structure and higher capillary density.

CONCLUSIONS

AER fat transplantation is a potential strategy to improve the survival and long-term retention of fat grafts. AER fat contained more dipeptidyl peptidase-4-expressing progenitor cells.

miR-26b-5p/TCF-4 Controls the Adipogenic Differentiation of Human Adipose-derived Mesenchymal Stem Cells

In this study, we assessed the ability of miR-26b-5p to regulate T cell factor 4 (TCF-4) expression and thereby control human adipose-derived mesenchymal stem cell (hADMSC) adipogenic differentiation. Adipogenic medium was used to induce hADMSC differentiation over a 6-d period. The ability of miR-26b-5p to interact with the TCF-4 mRNA was confirmed through both predictive bioinformatics analyses and luciferase reporter assays. Immunofluorescent staining was used to visualize the impact of miR-26b-5p inhibition or overexpression on TCF-4 and β-catenin levels in hADMSCs. Further functional analyses were conducted by transfecting these cells with siRNAs specific for TCF-4 and β-catenin. Adipogenic marker and Wnt/β-catenin pathway gene expression levels were assessed via real-time polymerase chain reaction and western blotting. β-catenin localization was assessed via immunofluorescent staining. As expected, our adipogenic media induced the adipocytic differentiation of hADMSCs. In addition, we confirmed that TCF-4 is an miR-26b-5p target gene in these cells, and that protein levels of both TCF-4 and β-catenin were reduced when these cells were transfected with miR-26b-5p mimics. Overexpression of this microRNA also enhanced hADMSC adipogenesis, whereas TCF-4 and β-catenin overexpression inhibited this process. The enhanced hADMSC adipogenic differentiation that was observed following TCF-4 or β-catenin knockdown was partially reversed when miR-26b-5p expression was inhibited. We found that miR-26b-5p serves as a direct negative regulator of TCF-4 expression within hADMSCs, leading to inactivation of the Wnt/β-catenin pathway and thereby promoting the adipogenic differentiation of these cells in vitro.

Lipofilling in Breast Oncological Surgery: A Safe Opportunity or Risk for Cancer Recurrence?

Lipofilling (LF) is a largely employed technique in reconstructive and esthetic breast surgery. Over the years, it has demonstrated to be extremely useful for treatment of soft tissue defects after demolitive or conservative breast cancer surgery and different procedures have been developed to improve the survival of transplanted fat graft. The regenerative potential of LF is attributed to the multipotent stem cells found in large quantity in adipose tissue. However, a growing body of pre-clinical evidence shows that adipocytes and adipose-derived stromal cells may have pro-tumorigenic potential. Despite no clear indication from clinical studies has demonstrated an increased risk of cancer recurrence upon LF, these observations challenge the oncologic safety of the procedure. This review aims to provide an updated overview of both the clinical and the pre-clinical indications to the suitability and safety of LF in breast oncological surgery. Cellular and molecular players in the crosstalk between adipose tissue and cancer are described, and heterogeneous contradictory results are discussed, highlighting that important issues still remain to be solved to get a clear understanding of LF safety in breast cancer patients.

Cannula Size Effect on Stromal Vascular Fraction Content of Fat Grafts

Background

Fat is an active and dynamic tissue composed of adipocytes supported by a structural framework known as the stromal vascular fraction (SVF). SVF is traditionally isolated by enzymatic processing, but new methods are being investigated to isolate it mechanically. Recent studies propose that fat harvested with larger cannulas has a higher survival rate, most likely due to a higher concentration of SVF.

Methods

Lipoaspirates were obtained from 10 patients who underwent elective liposuction using a 5-mm and a 1-mm cannula attached to a syringe using standard pressure. The fat was aspirated from the same area at adjacent sites. An estimated 5-mm fat particles were also cut down to 1-mm using a micronizer (Marina Medical). A 5-cm³ volume of each sample was compressed through a 0.5-mm opening strainer and rinsed with normal saline to extrude the oil. The resultant SVF left on the strainer was then measured in a 1-cm³ syringe.

Results

The volume extracted from a 5-mm cannula (mean, 0.23 cm³; SD, 0.10) versus a 1-mm cannula (mean, 0.11 cm³; SD, 0.06) was statistically significant (P = 0.009). An H&E-stained slide from the SVF was obtained for confirmation. Finally, 5-mm fat particles cut down to 1-mm particles using the micronizer resulted in an average volume of 0.20 cm³, which was higher than the average volume harvested with a 1-mm cannula.

Conclusions

Harvesting with a 5-mm cannula resulted in significantly more SVF than harvesting with a 1-mm cannula. Resizing fat particles harvested with a larger cannula down to 1-mm resulted in higher SVF than SVF obtained with a 1-mm cannula directly.

Human ESC-derived MSCs enhance fat engraftment by promoting adipocyte reaggregation, secreting CCL2 and mobilizing macrophages

Mesenchymal stem cells (MSCs) derived from somatic tissues have been used to promote lipotransfer, a common practice in cosmetic surgery. However, the effect of lipotransfer varies, and the mechanism of action remains vague. To address these questions, we differentiated human embryonic stem cells, a stable and unlimited source, into MSCs (EMSCs). Then we subcutaneously transplanted human fat aspirates together with EMSCs or PBS as a control into the back of nude mice. Within 24 h of transplantation, EMSCs promoted aggregation and encapsulation of injected fat tissues. Afterward, all grafts gradually shrank. However, EMSC-containing grafts were larger, heavier and had fewer dark areas on the surface than the control grafts. Histologically, more live adipocytes, vascular cells, and macrophages and less fibrosis were observed in EMSC-containing grafts than in the controls. Some EMSCs differentiated into vascular cells and adipocytes in the EMSC-containing grafts. RNA sequencing revealed that human RNA was shown to decline rapidly, while mouse RNA increased in the grafts; further, human genes related to extracellular matrix remodeling, adipogenesis, and chemokine (including CCL2) signaling were expressed at higher levels in the EMSC-containing grafts than they were in the controls. CCL2 knockout reduced macrophage migration towards EMSCs in vitro and early macrophage recruitment to the grafts and the pro-engraftment effect of EMSCs in vivo. Treating mice with a macrophage inhibitor abolished the EMSC effects and converted the grafts to heavy masses of cell debris. Together, these data demonstrate that EMSCs promote fat engraftment via enhanced tissue reconstitution and encapsulation of implanted tissues, which was followed by increased angiogenesis and adipocyte survival and reduced fibrosis, in which stimulated CCL2 signaling and mobilized macrophages play pivotal roles.

Tetramethylpyrazine/Ligustrazine Can Improve the Survival Rate of Adipose-Derived Stem Cell Transplantation

BACKGROUND

We aimed to study the effect of tetramethylpyrazine/ligustrazine (TMP) on the survival rate of adipose-derived stem cell (ADSC) transplantation.

METHODS

Human ADSCs were cultured and subcultured. Detection of cell growth was performed using CCK8 kit. A total of 12 BALB/c nude mice including 4 groups (group 1: ADSC-hyaluronic acid [HA] + phosphate-buffered saline [PBS]; group 2: ADSC-HA + TMP injection; group 3: ADSC-HA + TMP soaking; group 4: ADSC-HA + TMP injection + TMP soaking) were used for the animal experiments. Furthermore, hematoxylin-eosin staining and oil red O staining were conducted for the frozen section from the animal tissues. Besides, RNA was extracted from the samples, and reverse transcriptase-polymerase chain reaction experiment was performed. At last, samples were detected using transmission electron microscope.

RESULTS

Tetramethylpyrazine/ligustrazine resulted in significant increase for cell proliferation on the seventh day. It was easier to promote the growth of adipose cell after injection and soaking of TMP. Hematoxylin-eosin staining and oil red O stain showed that injection and soaking of TMP could significantly increase the size of fat. The relative expression of peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein α, and Alu in group 4 was significantly higher than that in other groups.

CONCLUSIONS

Tetramethylpyrazine/ligustrazine can improve the survival rate of ADSC transplantation. The possible mechanisms of it may be that TMP induces the expression of transcription factor associated with fat formation including peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein α, and Alu and then promotes the growth of adipose cell.

Adipose-Derived Mesenchymal Stromal Cells in Regenerative Medicine: State of Play, Current Clinical Trials, and Future Prospects

Significance: Wound healing is a complex process involving pain and inflammation, where innervation plays a central role. Managing wound healing and pain remains an important issue, especially in pathologies such as excessive scarring (often leading to fibrosis) or deficient healing, leading to chronic wounds. Recent Advances: Advances in therapies using mesenchymal stromal cells offer new insights for treating indications that previously lacked options. Adipose-derived mesenchymal stromal cells (AD-MSCs) are now being used to a much greater extent in clinical trials for regenerative medicine. However, to be really valid, these randomized trials must imperatively follow strict guidelines such as consolidated standards of reporting trials (CONSORT) statement. Indeed, AD-MSCs, because of their paracrine activities and multipotency, have potential to cure degenerative and/or inflammatory diseases. Combined with their relatively easy access (from adipose tissue) and proliferation capacity, AD-MSCs represent an excellent candidate for allogeneic treatments. Critical Issues: The success of AD-MSC therapy may depend on the robustness of the biological functions of AD-MSCs, which requires controlling source heterogeneity and production processes, and development of biomarkers that predict desired responses. Several studies have investigated the effect of AD-MSCs on innervation, wound repair, or pain management separately, but systematic evaluation of how those effects could be combined is lacking. Future Directions: Future studies that explore how AD-MSC therapy can be used to treat difficult-to-heal wounds, underlining the need to thoroughly characterize the cells used, and standardization of preparation processes are needed. Finally, how this a priori easy-to-use cell therapy treatment fits into clinical management of pain, improvement of tissue healing, and patient quality of life, all need to be explored.

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

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A Systematic Review of Autologous Fat Grafting in the Treatment of Acute and Chronic Cutaneous Wounds

There is a growing interest in the regenerative potential of autologous fat. Adipose-derived stem cells, within the stromal vascular fraction of lipoaspirate samples, demonstrate anti-inflammatory, immunomodulatory, and angiogenic properties. This systematic review aimed to determine the efficacy and safety of autologous fat therapies for wound healing, with an evaluation of the quality of evidence provided by the literature.

Mechanical emulsification of lipoaspirate by different Luer-Lok connector changes the viability of adipose derived stem cells in Nanofat

Nanofat grafting is a fat transfer procedure that uses a thin needle to smooth out wrinkles, thereby achieving the goal of skin rejuvenation. The Luer-Lok connector is one of the most common methods for obtaining Nanofat. In the present study, we compared three different Luer-Lok connectors (2.0 mm, 1.5 mm and 1.1 mm in diameter) in terms of their impact on the viability of adipose-derived stem cells (ADSCs) to determine the optimal size of the connector for efficient Nanofat grafting. We observed that a smaller diameter of the Luer-Lok connector created a higher mechanical shear force, which broke more fat cells during the emulsifying procedure, thereby reducing the viability of ADSCs from the stromal vascular fraction (SVF). Nanofat obtained from the 2-mm Luer-Lok connector had a better effect on skin rejuvenation than the 1.5-mm and 1.1-mm connectors. Therefore, this study presents an advance in the simple procedure of preparing Nanofat based on a previous technique and provides evidence that a procedure associated with less trauma may be a better choice.