Adipose Stromal Vascular Fraction Gel Grafting: A New Method for Tissue Volumization and Rejuvenation

Advanced methods to mechanically isolate stromal vascular fraction: A concise review

Adipose tissue is a highly attractive reservoir of stem cells due to its accessibility and abundance, and the SVF within it holds great promise for stem cell-based therapies. The use of mechanical methods for SVF isolation from adipose tissue is preferred over enzymatic methods, as it can be readily applied in clinical settings without additional processing steps. However, there is a lack of consensus on the optimal approach for mechanically isolating SVF. This comprehensive review aims to present and compare the latest mechanical isolation methods for SVF from adipose tissue, including centrifugation, filtration/washing, emulsification, vibration, and mincing/adiponizing. Each of these methods possesses unique advantages and limitations, and yet, no conclusive evidence has emerged demonstrating the superiority of one approach over the others, primarily due to the dearth of well-controlled prospective studies in this field.

Comparison of stromal vascular fraction cell composition between Coleman fat and extracellular matrix/stromal vascular fraction gel

As a mechanically condensed product of Coleman fat, extracellular matrix/stromal vascular fraction gel (ECM/SVF-gel) eliminates adipocytes, concentrates SVF cells, and improves fat graft retention. This study aims to compare SVF cell composition between Coleman fat and ECM/SVF-gel. Matched Coleman fat and ECM/SVF-gel of 28 healthy women were subjected to RNA-seq, followed by functional enrichment and cell-type-specific enrichment analyses, and deconvolution of SVF cell subsets, reconstructing SVF cell composition in the transcriptome level. ECM/SVF-gels had 9 upregulated and 73 downregulated differentially expressed genes (DEGs). Downregulated DEGs were mainly associated with inflammatory and immune responses, and enriched in fat macrophages. M2 macrophages, resting CD4+ memory T cells, M1 macrophages, resting mast cells, and M0 macrophages ranked in the top five most prevalent immune cells in the two groups. The proportions of the principal non-immune cells (e.g., adipose-derived stem cells, pericytes, preadipocytes, microvascular endothelial cells) had no statistical differences between the two groups. Our findings reveal ECM/SVF-gels share the same dominant immune cells beneficial to fat graft survival with Coleman fat, but exhibiting obvious losses of immune cells (especially macrophages), while non-immune cells necessary for adipose regeneration might have no significant loss in ECM/SVF-gels and their biological effects could be markedly enhanced by the ECM/SVF-gel's condensed nature.

Nasolabial Transfer Flap with Auricular Cartilage Graft after Fat Grafting for Nasal Ala Reconstruction in Parry-Romberg Syndrome

BACKGROUND

Alar atrophy associated with Parry-Romberg syndrome (PRS) can lead to significant nasal contour deformities. The primary objective of this study was to address nasal alar deformities in PRS patients through the application of a nasolabial transfer flap combined with an auricular cartilage graft after sequential fat grafting.

METHODS

All PRS patients with alar deformities who underwent our reconstructive surgery were included in this case series. Sequential fat grafting was performed on the affected nasolabial area, followed by a nasolabial transfer flap combined with an auricular cartilage graft. Surgical outcome and complications were recorded during postoperative follow-up.

RESULTS

From September 2021 to November 2023, a total of 14 PRS patients presenting nasal alar defects underwent nasolabial transfer flap combined with an auricular cartilage graft after sequential fat grafting. Complications at 1 month postoperatively included partial flap necrosis (21%), hyperplastic scarring (14%), undercorrection (14%), overcorrection (7%), and pain (7%). The surgery significantly improved the patient's nasal symmetry. FACE-Q questionnaire indicated the overall aesthetic outcome and quality of life were deemed satisfactory for all patients.

CONCLUSIONS

After sequential fat grafting, the nasolabial fold transfer flap with an auricular cartilage graft is effective to address alar deformities associated with PRS.

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.

Autologous fat grafting for cosmetic temporal augmentation: a systematic review

Background

Autologous fat grafting for temporal augmentation is increasingly popular in aesthetic surgery. However, its high absorption rate, unpredictable volume retention rate, and potential safety risks are significant drawbacks. Evaluation methods for the fat graft survival rate, especially volume retention in the temporal area, vary widely and tend to be more subjective than objective. Therefore, this systematic review aims to analyze the unpredictable volume retention rate, associated safety concerns, and the various assessment strategies following autologous fat grafting for cosmetic temporal augmentation.

Methods

We conducted a systematic review of manuscripts listed in the MEDLINE/PubMed database on autologous fat grafting for cosmetic temporal augmentation. Articles had to be available in full text and written in English. Studies not presenting human data or not discussing cosmetic indications were excluded. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Results

Eight articles were included. The average fat volume injected into each temporal region was 10.69 ml (range 6-17.5) on the right and 10.64 ml (range 5.9-17.4) on the left side. All included articles utilized photographic documentation before and after treatment, along with various questionnaires and scales (37.5% Likert Scale, 12.5% Hollowness Severity Rating Scale, 12.5% Visual Analogue Scale, 12.5% Allergan Temple Hollowing Scale). For objective assessment, one article (12.5%) used computed tomography, and another (12.5%) employed a three-dimensional scanning system to objectively evaluate fat graft survival.

Conclusion

Autologous fat grafting effectively addresses temporal hollowness, with high patient satisfaction and a favorable safety profile. However, the variability in fat retention rates highlights the need for more controlled studies to establish reliable, validated methods for evaluating fat graft survival in the temporal area, and to further assess the safety of this procedure.

Does Secondary Mechanical Manipulation of Lipoaspirate Enhance the Vasculogenic Potential of Fat Grafts? A Systematic Review

BACKGROUND

Fat grafting is a highly versatile option in the reconstructive armamentarium but with unpredictable retention rates and outcomes. The primary outcome of this systematic review was to assess whether secondary mechanically processed lipoaspirate favorably enhances the vasculogenic potential of fat grafts when compared to unprocessed lipoaspirate or fat grafts prepared using centrifugation alone. The secondary outcome was to assess the evidence around graft retention and improved outcomes when comparing the aforementioned groups.

METHODS

A search on MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials was conducted up to February 2022. All human and animal research, which provided a cross-comparison between unprocessed, centrifuged, secondary mechanically fragmented (SMF) or secondary mechanically disrupted (SMD) fat grafts, was included.

RESULTS

Thirty-one full texts were included. Vasculogenic potential was assessed by quantification of angiogenic growth factors and cellular composition. Cellular composition of mesenchymal stem cells, perivascular stem cells, and endothelial progenitor cells was quantified by fluorescence activated cell sorting (FACS) analysis. Fat graft volume retention rates and fat grafting to aid wound healing were assessed. Although the presence of industry-funded studies and inadequate reporting of methodological data in some studies were sources of bias, data showed SMF grafts contain an enriched pericyte population with increased vascular endothelial growth factor (VEGF) secretion. Animal studies indicate that SMD grafts may increase rates of fat graft retention and wound closure compared to centrifuged grafts; however, clinical studies are yet to show similar results.

CONCLUSIONS

In this systematic review, we were able to conclude that the existing literature suggests mechanically processing fat, whether it be through fragmentation or disruption, improves vasculogenic potential by enhancing angiogenic growth factor and relevant vascular progenitor cell levels. Whilst in vivo animal studies are scarce, the review findings suggest that secondary mechanically processed fat enhances fat graft retention and can aid with wound healing. Further clinical studies are required to assess potential differences in human studies.

Immediate SVF-Gel Injection Reduced Incision Scar Formation: A Prospective, Double-Blind, Randomized, Self-control Trial

BACKGROUND

Skin incision scars are cosmetically displeasing; the effects of current treatments are limited, and new methods to reduce scar formation need to be found.

OBJECTIVE

We sought to determine whether immediate postoperative injection of stromal vascular fraction gel (SVF-gel) could reduce scar formation at skin incision sites.

METHODS

A prospective, randomized, double-blind, self-controlled trial was conducted in patients who underwent breast reduction. SVF-gel was intradermally injected into the surgical incision on one randomly selected side, with the other side receiving saline as a control. At the 6-month follow-up, the incision scars were evaluated using the Vancouver scar scale (VSS) and visual analog scale (VAS). Antera 3D camera was used for objective evaluation.

RESULTS

The VSS score and VAS score were significantly different between the SVF-gel-treated side (3.80 ± 1.37, 3.37±1.25) and the control side (5.25 ± 1.18, 4.94 ± 1.28). Moreover, the SVF-gel-treated side showed statistically significant improvements in scar appearance, based on evidences from Antera 3D camera.

LIMITATIONS

This was a single-center, single-race, and single-gender study. Furthermore, the results were available only for the 6-month interim follow-up period.

CONCLUSION

Postoperative immediate SVF-gel injection in surgical incisions can reduce scar formation, and exert a preventive effect on scars.

LEVEL OF EVIDENCE I

Evidence obtained from at least one properly designed randomized controlled trial. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors   www.springer.com/00266 .

Fat or fillers: The dilemma in eyelid surgery

The aging of the periocular region has always aroused great interest. A fresh, young, and attractive sight determined an ever-greater attention to surgical and non-surgical techniques to obtain this result. In particular, the change in the concept of a young look, considered then "full", led to the increasing use of surgical (fat grafting) or medical (hyaluronic acid) filling techniques. Eyelid rejuvenation became increasingly popular in the field of cosmetic treatments, with a focus on achieving a youthful and refreshed appearance. Among the various techniques available, the choice between using fat grafting or fillers presented a clinical dilemma. In particular, what surgery considered of fundamental importance was a long-lasting result over time. On the other hand, aesthetic medicine considered it fundamental not to have to resort to invasive treatments. But what was the reality? Was there one path better than the other, and above all, was there a better path for patients? The minireview aims to explore the physiopathology, diagnosis, treatment options, prognosis, and future studies regarding this dilemma. We analyzed the literature produced in the last 20 years comparing the two techniques. Current literature reveals advancements in biomaterials, stem cell research and tissue engineering held promise for further enhancing the field of eyelid rejuvenation. The choice between fat grafting and fillers in eyelid cosmetic treatments presented a clinical dilemma. Understanding physiopathology, accurately diagnosing eyelid aging, exploring treatment options, assessing prognosis, and conducting future studies were essential for providing optimal care to patients seeking eyelid rejuvenation.

Exploring Preclinical Experiments with Different Fat Types for Autologous Fat Grafting

BACKGROUND

Autologous fat transplantation has been a cornerstone of tissue regeneration for decades. However, there is no standardized selection system or criteria for fat graft selection, often relying heavily on the surgeon's experience.

OBJECTIVES

This study aimed to investigate various types of fat derivatives, both in vitro and in vivo at the same condition.

METHODS

We collected traditional fat granules of different sizes and SVF-gel, evaluating the viability of ADSCs isolated from them and their performance after grafting into mice.

RESULTS

Large fat granules exhibited more complete adipocyte structures, and the isolated ADSCs demonstrated superior differentiation, proliferation, and secretion capacities. They also showed excellent volume retention after 12 weeks. In contrast, ADSCs isolated from SVF-gel displayed lower vitality. However, grafts from SVF-gel exhibited the highest volume maintenance rate among the four groups after 12 weeks, closely resembling normal adipose tissue and displaying significant vascularization. Compared to large fat granule and SVF-gel group, medium and small fat granule grafts exhibited lower volume retention and less angiogenesis.

CONCLUSIONS

Through preclinical studies, the flexible clinical use of different fat grafts can be tailored to their unique characteristics.

LEVEL OF EVIDENCE I

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 .

Comparative Efficacy and Safety of Cell-Assisted and Conventional Lipotransfer in Facial Filling: A Systematic Review and Meta-Analysis

PURPOSE

We aim to compare the efficacy and safety of cell-assisted lipotransfer (CAL) and conventional lipotransfer (CLT) in facial filling.

METHODS

The PubMed and Embase databases were searched for relevant publications until February 2023. All studies evaluating the efficacy and safety of cell-assisted and conventional lipotransfer in facial filling were included. We calculated pooled standardized mean difference (SMD) and 95% CIs for continuous outcomes and pooled risk ratio (RR) with 95% CIs for binary outcomes. The Cochrane's Risk of Bias Tool and the Newcastle-Ottawa Scale (NOS) were used to evaluate the quality of studies.

RESULTS

A total of 15 studies with 737 patients were included in this analysis. The fat survival rate and patient satisfaction rate were significantly higher in the CAL group compared to the CLT group (SMD: 3.04, 95% CI 2.09-3.99; RR: 1.34, 95% CI 1.08-1.67). However, no significant difference in complication rates (RR: 0.95, 95% CI 0.50-1.81) and a lower secondary operation rate in the CAL group (RR: 0.52, 95% CI 0.03-0.82) were observed. No obvious publication bias was observed in the funnel plot (Egger's P values = 0.084 and 0.403).

CONCLUSIONS

Based on the pooled results, we tentatively conclude that CAL may have superior fat survival rate and satisfaction rate compared to CLT in facial filling, without compromising patient safety. However, the majority of the included studies were observational studies with small sample sizes. Future research should focus on investigating the long-term efficacy and safety of these techniques.

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 Component Transplantation: An Advanced Fat-Grafting Strategy for Facial Rejuvenation

BACKGROUND

Autologous fat grafting is frequently used for volume augmentation and tissue regeneration. The uniform physical and biological characteristics of fat grafts, however, limit their optimal effects in various situations. Subjecting fat tissue to different mechanical processes results in adipose-derived products with distinct biological components and physical features. The present study describes a novel facial fat-grafting strategy, adipose component transplantation (ACT), that yields different adipose products that can be applied to specific injection sites.

METHODS

All patients who underwent ACT were evaluated retrospectively. Fat tissue samples were fractionated into high-density fat, adipose matrix complex, stromal vascular fraction gel, and adipose collagen fragment, as described. Each of these fractions was processed and injected into indicated recipient sites. Additional SVF gel was cryopreserved and, if necessary, injected during the following 3 months. Patients were followed up after 1, 2, 3, and 6 months, and annually thereafter.

RESULTS

From March of 2020 to September of 2021, 78 patients underwent whole face fat grafting using the ACT strategy. All operations and secondary injections of cryopreserved SVF gel were uneventful. There were no major complications, and final aesthetic results were satisfactory in 91% of patients.

CONCLUSIONS

The ACT strategy allows specific adipose products to be applied to specific injection sites, as warranted. Adipose matrix complex is indicated for sufficient rigid support, high-density fat when large volumes are required, SVF gel for precise injection and cryopreservation, and ACF as mesotherapy for skin rejuvenation. The ACT strategy optimizes the biological functions and physical features of different adipose-derived products.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Analyzing the Clinical Potential of Stromal Vascular Fraction: A Comprehensive Literature Review

Background: Regenerative medicine is evolving with discoveries like the stromal vascular fraction (SVF), a diverse cell group from adipose tissue with therapeutic promise. Originating from fat cell metabolism studies in the 1960s, SVF's versatility was recognized after demonstrating multipotency. Comprising of cells like pericytes, smooth muscle cells, and, notably, adipose-derived stem cells (ADSCs), SVF offers tissue regeneration and repair through the differentiation and secretion of growth factors. Its therapeutic efficacy is due to these cells' synergistic action, prompting extensive research. Methods: This review analyzed the relevant literature on SVF, covering its composition, action mechanisms, clinical applications, and future directions. An extensive literature search from January 2018 to June 2023 was conducted across databases like PubMed, Embase, etc., using specific keywords. Results: The systematic literature search yielded a total of 473 articles. Sixteen articles met the inclusion criteria and were included in the review. This rigorous methodology provides a framework for a thorough and systematic analysis of the existing literature on SVF, offering robust insights into the potential of this important cell population in regenerative medicine. Conclusions: Our review reveals the potential of SVF, a heterogeneous cell mixture, as a powerful tool in regenerative medicine. SVF has demonstrated therapeutic efficacy and safety across disciplines, improving pain, tissue regeneration, graft survival, and wound healing while exhibiting immunomodulatory and anti-inflammatory properties.

A New Minimally Invasive Procedure for Treating Plantar Heel Pain: Stromal Vascular Fraction Gel Grafting

METHODS

Fourteen patients who experienced plantar heel pain and underwent plantar heel SVF-gel grafting between January 2019 and June 2020 were included in this retrospective study. Foot pain and disability were measured at the screening visit and at the 3-, 6-, and 12-month follow-up visits. The volume of the heel fat pad was measured by magnetic resonance imaging.

RESULTS

Four of the patients had bilateral plantar heel pain, and 10 patients had unilateral plantar heel pain. All patients showed significant improvements in pain and foot function at 3 months after SVF-gel grafting compared with the baseline, with the greatest improvement at 6 months and the effect lasting 1 year or more. In addition, the thickness of the heel fat pad was significantly greater than at baseline at 3 months, and the effect lasted for 1 year or more.

CONCLUSION

Stromal vascular fraction gel grafting is a safe, minimally invasive, and effective approach to treat plantar heel pain.

Therapeutic potential of adipose tissue derivatives in skin photoaging

Photoaging, the primary cause of exogenous skin aging and predominantly caused by ultraviolet radiation, is an essential type of skin aging characterized by chronic skin inflammation. Recent studies have shown that oxidative stress, inflammation, skin barrier homeostasis, collagen denaturation and pigmentation are the main contributors to it. As a composite tissue rich in matrix and vascular components, adipose tissue derivatives have been recently gaining attention as potential therapeutic agents for various human diseases with fat-processing technology upgrades. This review analyzes both 'minimally treated' and 'nonminimally treated' fat derivatives to give an overview of the preclinical and clinical relevance of adipose tissue derivatives for antiphotoaging application, highlighting their good clinical prospects as well as discussing their safety and potential risks.

Mechanical Fractionation of Adipose Tissue-A Scoping Review of Procedures to Obtain Stromal Vascular Fraction

Clinical indications for adipose tissue therapy are expanding towards a regenerative-based approach. Adipose-derived stromal vascular fraction consists of extracellular matrix and all nonadipocyte cells such as connective tissue cells including fibroblasts, adipose-derived stromal cells (ASCs) and vascular cells. Tissue stromal vascular fraction (tSVF) is obtained by mechanical fractionation, forcing adipose tissue through a device with one or more small hole(s) or cutting blades between syringes. The aim of this scoping review was to assess the efficacy of mechanical fractionation procedures to obtain tSVF. In addition, we provide an overview of the clinical, that is, therapeutic, efficacy of tSVF isolated by mechanical fraction on skin rejuvenation, wound healing and osteoarthritis. Procedures to obtain tissue stromal vascular fraction using mechanical fractionation and their associated validation data were included for comparison. For clinical outcome comparison, both animal and human studies that reported results after tSVF injection were included. We categorized mechanical fractionation procedures into filtration (n = 4), centrifugation (n = 8), both filtration and centrifugation (n = 3) and other methods (n = 3). In total, 1465 patients and 410 animals were described in the included clinical studies. tSVF seems to have a more positive clinical outcome in diseases with a high proinflammatory character such as osteoarthritis or (disturbed) wound healing, in comparison with skin rejuvenation of aging skin. Isolation of tSVF is obtained by disruption of adipocytes and therefore volume is reduced. Procedures consisting of centrifugation prior to mechanical fractionation seem to be most effective in volume reduction and thus isolation of tSVF. tSVF injection seems to be especially beneficial in clinical applications such as osteoarthritis or wound healing. Clinical application of tSVF appeared to be independent of the preparation procedure, which indicates that current methods are highly versatile.

Ultra-condensed Fat: A Novel Fat Product for Volume Augmentation

BACKGROUND

Fat transplantation retention rate is individualized and unpredictable. The presence of blood components and oil droplets in the injected lipoaspirate increases inflammation and fibrosis in a dose-dependent manner, and is probably the key factor associated with poor retention.

OBJECTIVES

This study describes a volumetric fat grafting strategy based on optimization of grafts via screening intact fat particles and absorbing free oil droplets and impurities.

METHODS

Centrifuged fat components were analyzed by n-hexane leaching. A special device was applied to de-oil intact fat components and obtain ultra-condensed fat (UCF). UCF was evaluated by scanning electron microscopy, particle size analysis, and flow cytometric analysis. Histological and immunohistochemical changes were investigated in a nude mouse fat graft model over 90 days.

RESULTS

The lower 50% of centrifuged fat was concentrated to 40% of the original volume to obtain UCF. In UCF, the free oil droplet content was less than 10%, more than 80% of particles were larger than 1000 µm, and architecturally important fat components were present. The retention rate of UCF was significantly higher than that of Coleman fat on day 90 (57.5 ± 2.7% vs. 32.8 ± 2.5%, p < 0.001). Histological analysis detected small preadipocytes with multiple intracellular lipid droplets on day 3 in UCF grafts, indicative of early adipogenesis. Angiogenesis and macrophage infiltration were observed in UCF grafts soon after transplantation.

CONCLUSION

Adipose regeneration with UCF involves rapid macrophage infiltration and exit, resulting in angiogenesis and adipogenesis. UCF may serve as a lipofiller which is beneficial for fat regeneration.

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 http://www.springer.com/00266 .

Concentrated ultrasound-processed fat (CUPF): More than a mechanically emulsified graft

INTRODUCTION

Autologous fat grafting is still an evolving technique. Researchers have attempted to increase the survival rate of grafts by concentrating adipose-derived stem cells (ASCs). In this study, we investigate a novel method that combines ultrasonic processing and centrifugation to generate small fat particles termed concentrated ultrasound-processed fat (CUPF) for grafting.

METHODS

The standard approach for obtaining CUPF is described. The properties of processed fat, including CUPF, microfat, centrifuged fat, and nanofat, were investigated using histological observation. Comparative analyses were conducted on the cell number, viability, and immunophenotypic profile of stromal vascular fraction cells (SVFs). Cultured ASCs were evaluated for cell proliferation and adipogenic, osteogenic, and chondrogenic potential. The processed fats were transplanted and evaluated using in vivo and histological studies.

RESULTS

Compared with microfat, centrifuged fat, and nanofat, CUPF had a condensed tissue content and higher concentration of viable cells in a small tissue structure and could smoothly pass through a 27-gauge cannula. In the CUPF group, SVFs were isolated in great numbers, with high viability and a high proportion of CD29- and CD105-positive cells. ASCs from the CUPF group exhibited high proliferation and multilineage differentiation potential. The grafts from the CUPF group were well preserved, and histological quantification revealed an increase in the abundance of Ki67- and CD31-positive cells in the tissue.

CONCLUSIONS

Our study established a new fat processing strategy that combines ultrasonic processing and centrifugation to harvest small particle grafts named CUPF. CUPF concentrated a large number of ASCs and has great potential for regenerative therapy.

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 .

Pyramidal multiple-theory (multi-type, multi-method and multi-layer) for facial fat grafting

BACKGROUND

Age-related changes to the face pertinent anatomy and important aspects of autologous fat grafting have been widely applied in facial rejuvenation. Various types of autologous fat products (Macrofat, Microfat, SEFF, nanofat, and SVF-gel) with different properties and applicabilities have been introduced and available for surgeons.

METHODS

Key differences between common techniques for fat processing and infiltration. Develop a plan for patients based on site-specific facial anatomical zones, we suggested a pyramidal multiple-theory (multi-type, multi-method and multi-layer) for facial fat grafting. Based on the complicated mechanism of the face decrepitude in different layers of facial soft tissue, autologous fat products with various particle sizes and components into different layers.

RESULTS

Fifty-eight patients underwent this facial fat grafting strategy from June 2020 to Jan 2022. All achieved cosmetic improvements, with higher patients' satisfaction, and minor complications. Our facial fat grafting strategy takes advantage of different fat products and is able to address the physiological tissue changes during aging, more properly and targetedly, than the traditional facial fat grafting.

CONCLUSIONS

Fat grafting to the face aids in volume restoration and rejuvenation, thereby addressing soft-tissue atrophy associated with the aging face, acquired conditions, or congenital malformations. The technique described as "lipo-tumescence" has been successfully used in the breast and other regions of the body that have radiation damage and is discussed in this article specifically for the face and neck.

Correction of Mild-to-Moderate Sunken Upper Eyelids of Asians with Stromal Vascular Fraction Gel

INTRODUCTION

Fat grafting is an efficient and safe procedure for the correction of upper eyelid sulcus deepening. Stromal vascular fraction (SVF) gel has been proven to be an ideal fat derivative and can be widely used for facial augmentation. We aimed to determine the efficacy of SVF gel for the correction of a mild-to-moderate sunken superior sulcus among Asian patients.

METHODS

Patients with a mild-to-moderate sunken superior sulcus underwent SVF gel grafting of the sunken upper periorbital area. The primary result was the quantitative volume difference in the superior sulcus region before and after grafting. This was evaluated through three-dimensional VECTRA^® imaging. The secondary results included the aesthetic quantitative evaluation results (upper lid area and pretarsal space ratio), global aesthetic improvement scale (GAIS) score, and complications.

RESULTS

Thirty-one patients with mild-to-moderate sunken upper eyelids were included in this study. The average unilateral injected amount was 1.235 mL (± 0.171 mL). The 1-year delta volume was 0.801 ± 0.086 mL, and the effective survival volume was 65.3% (± 6.1%). The median preoperative pretarsal space and upper lid area ratio was 1.010 (± 0.150). The median postoperative pretarsal space and upper lid area ratio at 1 year was 0.159 (± 0.031) (n = 62; P < 0.0001), indicating a significantly reduced sunken appearance. The average GAIS score was 2.174 (± 0.391). All patients were satisfied with their surgical outcomes. The reoperation rate was 12.9%.

CONCLUSIONS

SVF gel is safe and effective for the treatment of a mild-to-moderate sunken superior sulcus and is associated with satisfactory clinical outcomes and short recovery times.

Engineered nanovesicles from stromal vascular fraction promote angiogenesis and adipogenesis inside decellularized adipose tissue through encapsulating growth factors

Acellular matrix is a commonly used biomaterial in the field of biomedical engineering and revascularization is the key process to affect the effect of acellular matrix on tissue regeneration. The application of bioactive factors related to angiogenesis has been popular in the regulation of revascularization, but the immune system clearance, uncontrollable systemic reactions, and other factors make this method face challenges. Recent reports showed that engineered cells into nanovesicles can reorganize cell membranes and encapsulate cellular active factors, extending the in vitro preservation of cytokines. However, the problems of exogenous biological contamination and tumorigenicity restricted the clinical transformation and wide application of this method. Here, we for the first time engineer stromal vascular fraction (SVF) which is extracted from fat into nanovesicles (SVF-EVs) for angiogenesis in the acellular matrix. SVF-EVs not only promote the migration of vascular endothelial cells in vitro, but also facilitate the lipogenic differentiation of mesenchymal stem cells. In vivo, SVF-EVs enhanced the retention of decellularized adipose tissue after transplanting to the subcutaneous area of nude mice. Immunofluorescence staining further showed that SVF-EVs promoted the formation of vascular networks with large lumen diameter in the grafted acellular matrix, accompanied by adipocyte regeneration peripherally. These findings reveal that SVF-EVs can be a viable method for accelerating revascularization in acellular matrix, and this process of squeezing tissue into nanovesicles shows the potential for rapid clinical transformation.

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

SVF-GEL Cryopreserved for Different Times Exhibits Varied Preservation and Regeneration Potential After Transplantation in a Mouse Model

BACKGROUND

Matrix vascular component (SVF) gels derived from fat preserve tissue integrity and cell viability under cryopreserved conditions, making them easy to inject again for later use. Here, we compared the preservation power and regeneration potential of SVF-gel under different cryopreservation times.

METHODS

The SVF-gel stored under - 20 °C, without cryoprotectant cryopreservation for 5, 15, and 45 days, with fresh SVF-gel as control. We evaluated the rate of volume retention after thawing the SVF-gel and the apoptosis rate of adipose-derived stem cells. Next, we analyzed retention rated, adipogenesis, angiogenesis, and connective tissue hyperplasia of the grafts, one month after subcutaneously transplanting the specimen into immunodeficient mice.

RESULTS

SVF-gel cryopreserved for 5 and 15 days exhibited no significant different in apoptosis rates relative to the control group. Extending the cryopreservation time to 45 days resulted in significantly increased and decreased apoptosis and volume retention rates of SVF-gel, respectively. SVF-gel grafts cryopreserved for 5 and 15 days exhibited no significant differences from those in the control group, although their weights and volumes still fluctuated. Extending the cryopreservation time to 45 days resulted in significantly decreased retention rates of the grafts. Histologically, extending freezing time resulted in a gradual decline in the graft's health adipose tissue, as well as decreased angiogenesis, and connective tissue hyperplasia.

CONCLUSION

Simple freezing of SVF-gel at - 20 °C conferred them with sufficient cell viability. Notably, short-term cryopreservation did not significantly increase the apoptosis rate, and it still had a certain regeneration after transplantation. However, prolonging freezing time to 45 days resulted in increased apoptosis rate and worsened transplantation effect.

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 .

Contouring and augmentation of the temple using stromal vascular fraction gel grafting

Background

Hollowing temples are common in aging Asians. Stromal vascular fraction (SVF) gel is a novel, mechanically processed adipose-derived product containing condensed adipose-derived stem cells and native extracellular matrix, allowing improved fat grafting. The present study evaluated the effectiveness of SVF-gel treatment on temple hollowing.

Methods

This prospective, single-center study included an SVF-gel grafting group (n = 34) and a Coleman's fat grafting group (n = 29). Temple contour was assessed using preoperative and postoperative photographs. Temple augmentation was quantified using three-dimensional (3D) technology and an MVS-600 3D scanner system. Patient satisfaction was assessed postoperatively.

Results

At 12 months follow-up, the minimal forehead width/forehead width ratio and the width of the temporal peak were increased in both groups (p < 0.05).; and the retention rate (41.2% ± 8.4%) of the SVF-gel group was significantly higher than that of Coleman's fat group (32.6% ± 8.8%; p < 0.05). Moreover, patients in the SVF-gel group reported higher satisfaction scores than those in Coleman's fat group.

Conclusions

SVF-gel is effective for temple contouring and augmentation., with increased efficacy compared with Coleman's fat.

Sequential Grafting of Fresh and Cryopreserved Fat After Mechanical Processing is a Safe and Effective Facial Rejuvenation Strategy

BACKGROUND

The survival rate of fat transplants is variable and consequently multiple operations are often required to achieve satisfactory results. Fat cryopreservation technology is a good solution to this problem. At present, cryopreservation of fats needs to be added with cryopreservation agents, which brings unsafety and operational complexity to clinical applications. An efficient and safe strategy for fat cryopreservation must be developed.

METHODS

A retrospective study was performed of all patients who underwent facial fat grafting and agreed to have their fat tissue cryopreserved from January 2018 to May 2021. Fat samples were physically processed to obtain SVF-gel, which was cryopreserved at - 20 °C for up to 3 months and injected after thawing. Images acquired by pre- and post-operative 3D scanning of the temporal region were compared to evaluate the retention rate of transplanted cryopreserved SVF-gel.

RESULTS

No patients experienced serious complications after receiving cryopreserved fat transplantation. The retention rate of cryopreserved SVF-gel was 46.3 ± 7.7% at 3 months and 43.1 ± 7.2% at 6 months after transplantation. The swelling duration was significantly shorter after cryopreserved SVF-gel transplantation (5.5 ± 0.8 days) than after fresh fat transplantation (7.5 ± 0.7 days) (p < .031).

CONCLUSION

Injection of cryopreserved SVF-gel achieves good retention rate for facial rejuvenation and has few side effects. Cryopreservation of SVF-gel is a safe and effective strategy for serial fat grafting for facial rejuvenation.

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 .

Adipose-Derived Stem Cells for Facial Rejuvenation

The interest in regenerative medicine is increasing, and it is a dynamically developing branch of aesthetic surgery. Biocompatible and autologous-derived products such as platelet-rich plasma or adult mesenchymal stem cells are often used for aesthetic purposes. Their application originates from wound healing and orthopaedics. Adipose-derived stem cells are a powerful agent in skin rejuvenation. They secrete growth factors and anti-inflammatory cytokines, stimulate tissue regeneration by promoting the secretion of extracellular proteins and secrete antioxidants that neutralize free radicals. In an office procedure, without cell incubation and counting, the obtained product is stromal vascular fraction, which consists of not only stem cells but also other numerous active cells such as pericytes, preadipocytes, immune cells, and extra-cellular matrix. Adipose-derived stem cells, when injected into dermis, improved skin density and overall skin appearance, and increased skin hydration and number of capillary vessels. The main limitation of mesenchymal stem cell transfers is the survival of the graft. The final outcomes are dependent on many factors, including the age of the patient, technique of fat tissue harvesting, technique of lipoaspirate preparation, and technique of fat graft injection. It is very difficult to compare available studies because of the differences and multitude of techniques used. Fat harvesting is associated with potentially life-threatening complications, such as massive bleeding, embolism, or clots. However, most of the side effects are mild and transient: primarily hematomas, oedema, and mild pain. Mesenchymal stem cells that do not proliferate when injected into dermis promote neoangiogenesis, that is why respectful caution should be taken in the case of oncologic patients. A longer clinical observation on a higher number of participants should be performed to develop reliable indications and guidelines for transferring ADSCs.

Indication-based protocols with different solutions for mechanical stromal-cell transfer

Background

Regenerative medicine is the fastest developing branch of plastic surgery in recent times. Adipose tissue is one of the largest and most important sources in the body for stromal cells. Although mechanical isolation methods are both very popular and have many advantages, they still have no accepted protocols.

Objective

We developed new protocols called indication-based protocols (IPs) for standardization and new techniques called mechanical stromal-cell transfer (MEST) by using ultra-sharp blades and dilution of adipose tissue with different solutions (saline, Ringer and 5% Dextrose)

Methods & material: In order to obtain the desired physical structure (liquid, gel, solid) and the desired volume, four different types of IPs have been defined. Adipose tissue was prediluted with different solutions using 10 or 20 cc injectors in IPs 1 and 2, while condensed adipose tissue was used directly in IPs 3 and 4.

Results

In MEST, stromal cells were obtained from 100 mL of condensed fat using different IPs with 92% mean viability and cell counts of 26.80–91.90 × 10⁶. Stromal cells can be obtained in the desired form and number of cells by using four different IPs.

Conclusion

Isolation of stromal cells by cutting fat with sharp blades will prevent the death of fat tissue and stromal cells and will allow high viability and cell count with our new technique. Predilution with different solutions: Diluting the condensed adipose tissue with the desired solutions (saline, Ringer or 5% Dextrose) before the adinizing process will provide even more stromal cells.

Lay Summary

Obtaining regenerative stromal cells from adipose tissue can be done by two methods: Enzymatic and mechanical. Mechanical methods have many advantages. Although mechanical stromal cell extraction from adipose tissue is very popular and many techniques have been described, there are still no accepted protocols, definition for the end product, and no consensus on the status of the stromal cells. In this study, stromal cells were obtained mechanically by using ultra-sharp blade systems, without exposing adipose tissue to blunt trauma. Thus, a higher number of cells and higher viability could be obtained. An “Indication based” protocol has been defined for the first time in order to obtain the desired number and status (solid, semi-solid, liquid)

end product. Diluting the condensed adipose tissue with the desired solutions (saline, Ringer or 5% Dextrose) before the adinizing process will provide even more stromal cells. This will provide an opportunity for clinicians to obtain and apply a stromal cell solution for different indications in different anatomical regions.

Improving Low-Density Fat by Condensing Cellular and Collagen Content through a Mechanical Process: Basic Research and Clinical Applications

BACKGROUND

Large-volume fat grafting results in high absorption and complication rates. Low-density fat includes small numbers of viable cells and considerable oil, resulting in nodules and oil cysts. This study evaluated a strategy for large-volume fat grafting using a mechanical process to condense low-density fat and transplanting it with high-density fat.

METHODS

Low-density fat, defined as the upper half of centrifuged lipoaspirates, was emulsified by intersyringe shifting and centrifuged to obtain condensed low-density fat. Fresh condensed low-density fat was analyzed by counting cells in the stromal vascular fraction, and by electron scanning and Western blotting. The retention rate and histologic changes of the product were analyzed using a fat grafting model in nude mice. Transplantation with a combination of condensed low-density fat and high-density fat was tested in patients undergoing breast reconstruction and breast augmentation.

RESULTS

The condensed low-density fat derived from low-density fat contained a large number of stromal vascular fraction cells and collagens, comparable to that of high-density fat and much higher than in low-density fat and Coleman fat. Retention rates 12 weeks after transplantation were higher for condensed low-density fat (55.0 ± 7.5 percent) than for low-density fat (31.1 ± 5.7 percent) and Coleman fat (41.1 ± 6.8 percent), with condensed low-density fat having fewer oil cysts and lower macrophage infiltration. Patients grafted with combined condensed low-density fat and high-density fat showed good long-term volume retention.

CONCLUSIONS

Using mechanical methods to condense low-density fat to a level comparable to that of high-density fat is a practical method of improving fat graft retention and avoiding severe complications. This new strategy may improve the quality of lipoaspirates for patients requiring large-volume augmentation.

Comparison of the Rheological Properties and Structure of Fat Derivatives Generated via Different Mechanical Processing Techniques: Coleman Fat, Nanofat, and Stromal Vascular Fraction-Gel

Importance: Coleman fat, nanofat, and stromal vascular fraction-gel (SVF-gel) are three widely used fat derivatives. However, their rheological properties and structure remain unknown. Objectives: To disclose the rheological properties and structure of three different fat derivatives. Design, Settings, and Participants: Fat tissues obtained from eight different donors were processed into three separate groups: Coleman fat, nanofat, and SVF-gel (n = 8); their viscoelastic properties and structure were determined. Intervention: Oscillation measurements were performed in the context of serrated 25-mm parallel-plate geometry with a 1.2-mm gap at 25°C. In addition, fat samples were fixed using a patented protocol and observed under scanning electron microscopy. Main Outcomes and Measures: Comparison of the viscoelastic properties, microstructure, and particle size. Results: At 0.77 Hz, the elastic modulus of SVF-gel, Coleman fat, and nanofat was 201.6 ± 0.74, 69.94 ± 15.61, and 34.89 ± 3.484 Pa, respectively; their viscosity was 44.06 ± 3.038, 15.37 ± 2.0380, and 7.516 ± 0.7250 mPa, respectively. The particle size of SVF-gel, Coleman fat, and nanofat was 106.0 ± 4.796, 86.93 ± 3.597, and 12.61 ± 7.603 μm, respectively. Conclusion and Relevance: Mechanical processing may impact graft efficacy. The characterization of the rheological properties and structure of different fat derivatives in this study may help surgeons select the better type of tissue for a given intervention; however, further studies are still required.

Comparison of Microfat, Nanofat, and Extracellular Matrix/Stromal Vascular Fraction Gel for Skin Rejuvenation: Basic Research and Clinical Applications

BACKGROUND

Over the past 2 decades, fat grafting has been extensively applied in the field of tissue regeneration.

OBJECTIVES

The aim of this study was to investigate the therapeutic potential of microfat, nanofat, and extracellular matrix/stromal vascular fraction gel (SVF-gel) in skin rejuvenation.

METHODS

Microfat was harvested by a cannula with multiple 0.8-mm smooth side holes and processed with a fat stirrer to remove fibers. Nanofat and SVF-gel were prepared according to previously reported methods, and their structure and viability were evaluated. Then, SVF cells from the 3 types of samples were isolated and characterized, and the cell viability was compared.

RESULTS

The microstructure of the 3 samples showed distinct differences. The microfat group showed a diameter of 100 to 120.0 μm under the microscope and presented a botryoid shape under calcein acetoxymethyl (calcein-AM)/propidium iodide staining. Scanning electron microscopy analysis showed that the microfat maintained an integral histologic structure. In the nanofat group, no viable adipocytes and no normal histologic structure were observed, but high levels of free lipids were noted. The SVF-gel group showed uniform dispersion of cells with different sizes and parts of the adipose histologic structure. Cell count and culture revealed that the number of viable SVF cells decreased distinctly in the nanofat group compared with the microfat group. In contrast, the number of viable SVF cells in the SVF-gel group increased moderately. Clinical applications with microfat showed marked improvements in skin wrinkles.

CONCLUSIONS

Microfat can preserve the integrity of the histologic structure and presents the advantages of subcutaneous volumetric restoration and improvement of skin quality in skin rejuvenation compared with the nanofat and SVF-gel.

LEVEL OF EVIDENCE: 5

High-Density Fat Grafting Assisted Stromal Vascular Fraction Gel in Facial Deformities

Autologous fat grafting is commonly used for soft tissue augmentation and reconstruction, this technique is limited by a high rate of graft absorption. The stromal vascular fraction gel (SVF-gel) grafting for facial volume augmentation can exert a positive effect on skin rejuvenation, but its major limitation is the low rate of conversion of Coleman fat. The purpose of our study was to investigate a novel surgery using performing high-density fat in combination with SVF-gel in the treatment of hemifacial atrophy, or Romberg diseases. From October 2017 to October 2019, 13 patients with hemifacial atrophy underwent high-density fat transfer with SVF-gel injection. The outcome was determined by the difference in presurgery and postsurgery FACE-Q modules (FACE-Q conceptual framework: 1, Satisfaction with Facial Appearance; 2, Health-Related Quality of Life; 3, Negative Sequelae; 4, Satisfaction with Process of Care), which were designed as patient-reported outcome instrument to evaluate the unique outcomes of patients undergoing facial cosmetic procedures.

The excellent cosmetic results were observed during follow-up periods, with no adverse events was seen in the treatment group. All patients showed improvements in facial augmentation and contour. In patients with facial volume loss, high-density fat transfer with SVF-gel facial injection resulted in significantly higher improvement scores and better patient satisfaction. The patient-reported FACE-Q modules presurgery and postsurgery results showed statistically significant improvement (P < 0.05). This high-density fat in combination with SVF-gel is an effective method of correcting the facial volume loss that leave no complications during follow-up, having a satisfactory volumization effect. This could largely facilitate the clinical utilization of fat.

Regenerative and stem cell-based techniques for facial rejuvenation

This review discusses the most novel ideas and modalities being incorporated into facial rejuvenation. Recent innovative techniques include the use of regenerative stem cell techniques and regeneration supportive modalities such as nano-technology or gene therapies. This review aims to investigate approaches that are less well known and lacking established evidence in order to proactively study these techniques prior to them becoming popularized. These applications and relevant research were reviewed in the context of both surgical and non-surgical modalities in clinical practice. Future directions include the concept of "precision cosmetic medicine" utilizing gene editing and cellular therapies to tailor rejuvenation techniques based on each individual's genetic make-up and therefore needs.

Effect of Co-transplanting Stromal Vascular Fraction-Gelatin and Platelet-Rich Fibrin on the Long-Term Maintenance of Fat Volume

OBJECTIVE

In the present study, we aimed to investigate the survival of stromal vascular fraction-gelatin (SVF-gel) grafts and determine whether co-transplantation of SVF-gel and platelet-rich fibrin (PRF) improves long-term maintenance of fat volume (Wei et al. in Oncotarget 8:68542-68556, 2017) in a rabbit model.

METHODS

SVF-gel was transplanted into the ears of 12 rabbits with (experimental group) or without PRF (control group). Transplantation retention was evaluated based on weight, histology, and immunohistochemistry.

RESULTS

In the 2nd and 4th weeks, the volume of fat was larger in the experimental group than in the control group. In the 6th week, the absorption of fat was noticeable in both groups, and there was no significant difference in the fat survival rate between the two groups (experimental group: 1.051 ± 0.144 and control group: 0.789 ± 0.232, P > 0.05). HE staining results: At week 2, adipocytes were observed in the experimental group and tended to mature over time. These adipocytes also exhibited an ordered arrangement. Adipocytes with abnormal morphology appeared in the control group in the 4th week. At different weeks, there were more inflammatory cells and fibroblasts in the experimental group than in the control group, and they were arranged in an ordered fashion. Immunohistochemical results: More brown areas were observed in the experimental group than in the control group, and the morphology and distribution of adipocytes in the experimental group were better than those in the control group. The distribution of fibrocytes was also more regular in the experimental group than in the control group.

CONCLUSION

SVF-gel cannot maintain long-term filling in rabbit ears. The addition of PRF has no influence, although PRF can induce SVF-gel to transform into adipocytes, and the anti-inflammatory effect is noticeable in the early period following the procedure. Co-transplantation also helped to ensure orderly arrangement of fibrin. There were no "volume preservation differences in this experimental model" perhaps there are differences if other models/methodology are employed. No Level Assigned This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine Ratings, please refer to Table of Contents or online Instructions to Authors - www.springer.com/00266 .

Stromal vascular fraction and emulsified fat as regenerative tools in rejuvenation of the lower eyelid area

In the lower eyelid area, dermal melanocytosis, fine lines, skin atrophy, dryness, and loss of subcutaneous fat tissue represent the initial signs of aging. Beside the addition of volume, adipose tissue injections can also improve pigmentation and skin texture. Clinical studies of simultaneous stromal vascular fraction (SVF) and emulsified fat transfers have not been reported so far. Our aim was to investigate the clinical results of transferring SVF and emulsified fat into the lower eyelid area. A total of 16 patients underwent tumescent liposuction and injection of SVF and emulsified fat into the lower eyelid area. For preparation of SVF and emulsified fat, ACP double syringes with 2.4, 1.4, and 1.2 mm connectors, and a swing-out rotor centrifuge, were used. At follow-up, improvements on before and after pictures were rated by the treating physician and two independent physicians, using the global aesthetic improvement scale (GAIS). Clinical outcomes were rated as exceptional, very improved, or improved in all patients, with an average GAIS score of 1.6. No serious adverse events occurred. Our initial results suggest that SVF and emulsified fat are safe and effective tools for skin rejuvenation and correction of volume deficiencies in the lower eyelid area. More studies need to be conducted to corroborate these encouraging findings.

Not Stromal Vascular Fraction (SVF) or Nanofat, but Total Stromal-Cells (TOST): A New Definition. Systemic Review of Mechanical Stromal-Cell Extraction Techniques

The most important and greatest source in the body for regenerative cells is fat tissue. Obtaining regenerative cells from adipose tissue can be done in two ways: Enzymatic and mechanical. The regenerative cell cocktail obtained by the enzymatic method, including stem cells, is called Stromal vascular fracture (SVF). In the literature, there is no clear definition of regenerative cells obtained by mechanical method. We systematically searched the techniques and definitions for stromal cells obtained from adipose tissue by scanning different databases. To evaluate the mechanical stromal-cell isolation techniques and end products from adipose tissue. Systematic review of English and non-English articles using Embase, PubMed, Web of Science and Google scholar databases. Search terms included Nanofat, fragmented fat, mechanical stromal / stem cell, mechanical SVF, SVF gel. We screened all peer-reviewed articles related with mechanical stromal-cell isolation. Author performed a literature query with the aforementioned key words and databases. A total of 276 publications containing the keywords we searched were reached. In these publications, there are 46 different definitions used to obtain mechanical stromal cells. The term SVF is only suitable for enzymatic methods. A different definition is required for mechanical. The most used term nanofat is also not suitable because the product is not in both "fat" and in "nanoscale". We think that the term total stromal-cells would be the most appropriate definition since both extracellular matrix and all stromal cells are protected in mechanical methods.

Anatomic Characteristics and Treatment of the Midcheek Groove by Deep Filling

BACKGROUND

Because the anatomic mechanisms underlying the formation of the midcheek groove are unclear, treatments to date have resulted in unsatisfactory outcomes.

OBJECTIVE

This study investigated the anatomical foundation of the midcheek groove and evaluated appropriate treatment methods.

MATERIALS AND METHODS

Six cadaver hemifacial specimens were subjected to gross anatomic dissection and 6 to P45 sheet plastination. Based on the anatomic results, the area under the orbicularis oculi muscle (OOM) was selected for deep filling. Patients were evaluated by measuring 3D depth, regrading, and self-assessment.

RESULTS

The medial band was observed to be an important structure of the OOM, with the facial projection overlapping the midcheek groove trace. Two of the 6 P45 specimens were found to have compact fibroelastic bundles (CFBs) between the medial band and the dermis. Deep filling of the area under the OOM significantly reduced the depth of each section in all 34 patients (p < .001). Grades 3 and 4 midcheek grooves were downgraded distinctively. Most subjects expressed satisfaction with outcomes.

CONCLUSION

Formation of the midcheek groove is associated with the passage of CFBs. Deep filling of the area under the OOM effectively improves the midcheek grooves.

Correction of the Tear Trough Deformity and Concomitant Infraorbital Hollows With Extracellular Matrix/Stromal Vascular Fraction Gel

BACKGROUND

The tear trough deformity is a sign of eye aging. Filling is an ideal choice for the tear trough accompanied by infraorbital hollows.

OBJECTIVE

To evaluate the efficacy and safety of stromal vascular fraction gel (SVF-gel) as a filler for the tear trough deformity which is combined with infraorbital hollows.

MATERIALS AND METHODS

From July 2017 to June 2018, 33 patients underwent autologous fat aspiration and were followed up successfully. Stromal vascular fraction gel was used to correct patients with bilateral Barton I/II; tear trough deformity and infraorbital hollows. Improvement was evaluated by measuring skin-periosteal depth, 3D volume, global aesthetic improvement scale (GAIS), and patient self-assessment.

RESULTS

Skin-periosteal depth improved significantly (p < .001). The volumetric increment of the tear trough and infraorbital regions increased 2.132 ± 0.671 mL, and the retention rate was excellent (72.87 ± 10.23%). The GAIS showed a high score (2.5 ± 0.5 points), with patient self-assessment showing satisfactory results for all 7 questions on the questionnaire.

CONCLUSION

The high retention rate of SVF-gel suggests that it can provide an effective solution to tear trough deformity accompanied by infraorbital hollows.

Update on Nonfacial Fat Transplantation

BACKGROUND

Fat transplantation is becoming increasingly popular for off-face rejuvenation.

OBJECTIVE

To provide an update in the literature of current knowledge and emerging concepts in the use of fat transplantation for nonfacial applications.

MATERIALS AND METHODS

This update includes the potential benefits and risks of using fat transfer techniques on the body.

RESULTS

The current literature and author experiences are provided to help understand this growing field of aesthetic procedures.

CONCLUSIONS

The use of nonfacial fat transplantation is increasing and will become a larger part of aesthetic practices.

[Research progress of adipose-derived stem cells in promoting the repair of peripheral nerve injury]

OBJECTIVE

To summarize the research progress of adipose-derived stem cells (ADSCs) in promoting the repair of peripheral nerve injury.

METHODS

The related literature at home and abroad in recent years was widely reviewed, the mechanism of ADSCs promoting the repair of peripheral nerve injury was introduced, and its basic research progress was analyzed and summarized. Finally, the clinical transformation application of ADSCs in the treatment of peripheral nerve injury was introduced, the existing problems were pointed out, and the new treatment regimen was prospected.

RESULTS

ADSCs have the function of differentiation and paracrine, and their secreted neurotrophic factors, antiapoptosis, and antioxidant factors can promote the repair of peripheral nerve injury.

CONCLUSION

ADSCs are rich in content and easy to obtain, which has a definite effectiveness on the repair of peripheral nerve injury with potential clinical prospect.

The rise of stem cells in skin rejuvenation: A new frontier

Stem cells have recently garnered increased attention, especially pertaining to their use in cutaneous rejuvenation. Their popularity has continued to grow with patients and consumers alike, which has followed the substantial marketing bolstering them. Although limited, studies have begun to demonstrate promise in the field of esthetics. We review the prominent studies in the literature to shed more light on the use of stem cells for cosmetic practitioners.

The Effects of Facial Lipografting on Skin Quality: A Systematic Review

BACKGROUND

Autologous lipografting for improvement of facial skin quality was first described by Coleman in 2006. The current dogma dictates that adipose tissue-derived stromal cells that reside in the stromal vascular fraction of lipograft contribute to skin rejuvenation (e.g., increased skin elasticity), a more homogenous skin color, and softening of skin texture. Nowadays, many studies have been reported on this "skin rejuvenation" effect of autologous fat grafting. This systematic review was undertaken to assess the efficacy of autologous lipografting on skin quality.

METHODS

The MEDLINE, Embase, Cochrane Central, Web of Science, and Google Scholar databases were searched for studies evaluating the effect of autologous lipografting on facial skin quality (May 11, 2018). Outcomes of interest were skin texture, color, and elasticity in addition to histologic outcomes and number of complications.

RESULTS

Nine studies were included, with 301 patients treated in total. No meta-analysis could be performed because of heterogeneity of the metrics and outcomes. Eight studies reported increased skin elasticity; improvement in skin texture; and a more homogeneous skin color after treatment with lipografting, cellular stromal vascular fraction, or nanofat. One study reported no increased skin elasticity after lipografting. Histologic improvement was seen after lipografting and adipose tissue-derived stromal cell injections. However, in general, the level of evidence of the included studies was low. No serious complications were reported.

CONCLUSION

Autologous facial lipografting and cellular stromal vascular fraction and adipose tissue-derived stromal cell injections hardly seem to improve facial skin quality but can be considered a safe procedure.

Mechanical Micronization of Lipoaspirates for the Treatment of Horizontal Neck Lines

BACKGROUND

Horizontal neck wrinkles develop as a result of the aging process. Stromal vascular fraction (SVF) gel, which is rich in extracellular matrix and functional cells, can be produced by a series of simple mechanical processes, including intersyringe shifting and centrifugation. This study aimed to assess stromal vascular fraction gel in the treatment of horizontal neck wrinkles.

METHODS

This single-center study included female patients with horizontal neck wrinkles (Fitzpatrick types II to IV) treated with either SVF gel or botulinum toxin type A (BTX A) injection. SVF gel was first diffusely distributed subcutaneously along the neck line and then injected in a diluted way intracutaneously at points 0.5 cm apart along the horizontal lines. BTX A was injected at points 1.5 cm apart (2 U in each injection site). Satisfaction and improvement scores were compared between the two groups, and the collagen content of the neck wrinkle was compared by histologic evaluation before and after treatment.

RESULTS

Twenty-eight patients received SVF gel and 22 received BTX A. In patients with type II neck wrinkles, BTX A and SVF gel treatment resulted in similar improvement scores and patient satisfaction in the first 3 months. In patients with type III and IV neck wrinkles, SVF gel resulted in significantly higher improvement scores and better patient satisfaction. A longer duration of adverse events was seen in the SVF gel treatment group. Histologic assessment suggested that SVF gel increased the collagen density of neck wrinkles.

CONCLUSION

SVF gel is an effective treatment for horizontal neck wrinkles, particularly in patients with type III and IV wrinkles.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Fat Grafting for Facial Rejuvenation Using Stromal Vascular Fraction Gel Injection

This study used stromal vascular fraction gel (SVF-gel), a mechanically processed fat-derived product, to treat eye bag and tear trough deformity. SVF-gel is prepared by a process of centrifugation and intersyringe shifting and is particularly rich in SVF cells and native adipose extracellular matrix. SVF-gel injection is used alone or combined with transconjunctival eye bag removal. High satisfaction was noted among patients treated with SVF-gel injection for periorbital rejuvenation with fairly low complication rates. SVF-gel injection is a good alternative to assist transconjunctival lower eyelid blepharoplasty and correct the palpebromalar groove, tear trough deformity, and supraorbital hollow.

An Overview of Principles and New Techniques for Facial Fat Grafting

Facial fat grafting is a small-volume procedure and is primarily performed for facial rejuvenation, contouring, or regenerative surgery. The unsatisfying retention rate after fat grafting, however, led to unpredictable outcomes, subsequent multiple procedures, and even some complications. A variety of methods have been proposed to enhance the results of facial fat grafting, including several established surgical principles and many possible new techniques. Adding stem cells, fat preparations, and platelet concentrates may improve the survival after fat grafting but randomized controlled clinical studies are needed to determine their safety and efficacy as well as clinical indications for each technique.

Mechanical process prior to cryopreservation of lipoaspirates maintains extracellular matrix integrity and cell viability: evaluation of the retention and regenerative potential of cryopreserved fat-derived product after fat grafting

Background

Cryopreservation of fat grafts facilitates reinjection for later use. However, low temperature and thawing can disrupt tissues and cause lipid leakage, which raises safety concerns. Here, we compared the cryopreservation potential of stromal vascular fraction (SVF) gel processed from lipoaspirate with that of fat.

Methods

Human SVF gel and fat were cryopreserved at − 20 °C without cryoprotectant for 1 month. Fresh SVF gel and fat were used as controls. Tissue viability, adipose-derived stem cell (ASC) function, and the extracellular content were evaluated. At 3 months after transplanting the specimens to immunocompromised mice subcutaneously, the grafts were examined for retention, tissue engraftment, and inflammatory levels. The regenerative effect of cryopreserved SVF gel was evaluated in a murine ischemic wound healing model.

Results

At 1 month, the cell death rate in the SVF gel group was 36 ± 2%. The survived ASCs not only could be isolated via explant culture but also preserved colony-forming and differentiation. However, prolonged cryopreservation exacerbated apoptosis. Assessment of recovered tissues showed that the morphology, cell viability, and extracellular protein enrichment were better in SVF gel-preserved tissues than in frozen fat. At 3 months after lipotransfer, the retention ability of 1-month cryopreserved fat was 41.1 ± 9% compared to that of 1-month cryopreserved SVF gel. Immunostaining results showed that adipose tissue regeneration and integrity in the 1-month cryopreserved SVF gel group were superior to those of the cryopreserved fat group. The cryopreserved SVF gel also accelerated healing of the ischemic wound, compared with cryopreserved fat.

Conclusion

Cryopreserved SVF gel maintained tissue integrity and cell viability and resulted in a better long-term retention rate than that of cryopreserved fat. Cryopreserved SVF gel also showed superior regenerative potential and improved ischemic wound healing.

Human adipose liquid extract induces angiogenesis and adipogenesis: a novel cell-free therapeutic agent

BACKGROUND

Taking advantage of cellular paracrine mechanisms, the secretome of adipose-derived stem cells (ADSCs) and adipose tissue has been demonstrated to induce tissue repair and regeneration in various ischemic and impaired conditions. However, these cell-based therapies have been hindered by issues, such as inherent safety and cost-efficiency for clinical applications. In this study, we prepared a liquid cell-free extract from human adipose tissue [adipose liquid extract (ALE)] and evaluated its potential therapeutic efficacy.

METHODS

ALE was prepared from human subcutaneous adipose tissue using a rapid and physical approach, and the protein components in ALE were identified using mass spectrometry analysis. In vivo, the therapeutic effect of this agent was investigated on wound healing in C57BL/6 mice, and wound healing rate, vessel density, and neo-adipocyte formation in wounded skins were measured at days 3, 7, 11, and 14. In vitro, the effect of ALE on the viability of human ADSCs, tube formation of human umbilical vein endothelial cells (HUVECs), and adipogenic differentiation of ADSCs were tested.

RESULTS

The results demonstrated that ALE contained a variety of growth factors and did not affect cell viability. ALE-treated wounds exhibited accelerated wound healing with increased vessel density and formation of neo-adipocytes compared to that of control wounds. Moreover, when added as a cell culture supplement, ALE effectively induced tube formation of HUVECs and lipid accumulation in ADSCs. ALE-treated ADSCs also exhibited elevated levels of adipogenic gene expression.

CONCLUSIONS

ALE is a novel growth-rich therapeutic agent that is cell-free and easy to produce. Besides, it is also able to induce angiogenesis and adipogenesis both in vitro and in vivo, thus indicating that it could be used for wound repair and soft tissue regeneration.