Isolation of Stromal Vascular Fraction by Fractionation of Adipose Tissue

Stromal vascular fraction: Mechanisms and application in reproductive disorders

Stromal vascular fraction (SVF) is a complex mixture derived from adipose tissue, consisting of a variety of cells. Due to its potential for tissue repair, immunomodulation, and support of angiogenesis, SVF represents a promising frontier in regenerative medicine and offers potential therapy for a range of disease conditions. In this article, we delve into the mechanisms through which SVF exerts its effects and explore its potential applications in treating both male and female reproductive disorders, including erectile dysfunction, testicular injury, stress urinary incontinence and intrauterine adhesion.

GMP Compliant Production of Therapeutic Components of Autologous Adipose Tissue

Adipose tissue is a popular source of tissue for cellular therapy in the field of regenerative medicine. The regenerative potential is often ascribed to the presence of stromal vascular fraction (SVF) containing extracellular matrix and multipotent stromal cells secreting a plethora of growth factors to create a regenerative environment. SVF can be isolated by means of enzymatic or mechanical isolation procedures and expanded in culture or directly used intraoperatively. Depending on the clinical use of SVF, specific regulatory requirements are demanded and might classify SVF as an advanced therapy medicinal product (ATMP). As an ATMP, SVF must be manufactured, processed, and controlled according to good manufacturing practice (GMP) guidelines to ensure safety and quality. Subsequently, the GMP standards require extensive validation, process control, and characterization of SVF. Here we report a GMP-compliant production of clinical grade tissue (tSVF) by means of fractionation of adipose tissue (FAT) procedure. Previous validation studies demonstrated tSVF to be safe and feasible for clinical use intraoperatively according to GMP standards with the appropriate release criteria. The presented procedures can be used as a template for the development of an investigational medicinal product dossier to be enclosed in future clinical trials (Fig. 1).

A Versatile Skin-Derived Extracellular Matrix Hydrogel-Based Platform to Investigate the Function of a Mechanically Isolated Adipose Tissue Stromal Vascular Fraction

Introduction: To accelerate cutaneous wound healing and prevent scarring, regenerative approaches such as injecting a mechanically derived tissue stromal vascular fraction (tSVF) are currently under clinical and laboratory investigations. The aim of our study was to investigate a platform to assess the interaction between skin-derived extracellular matrix (ECM) hydrogels and tSVF and their effects on their microenvironment in the first ten days of culture. Material and Methods: A tSVF mixed with ECM hydrogel was cultured for ten days. After 0, 3, 5, and 10 days of culture viability, histology, immunohistochemistry, gene expression, and collagen alignment and organization were assessed. Results: The viability analysis showed that tSVF remained viable during 10 days of culture and seemed to remain within their constitutive ECM. The fiber analysis demonstrated that collagen alignment and organization were not altered. No outgrowth of capillaries was observed in (immuno)histochemical staining. The gene expression analysis revealed that paracrine factors TGFB1 and VEGFA did not change and yet were constitutively expressed. Pro-inflammatory factors IL1B and IL6 were downregulated. Matrix remodeling gene MMP1 was upregulated from day three on, while MMP14 was upregulated at day three and ten. Interestingly, MMP14 was downregulated at day five compared to day three while MMP2 was downregulated after day zero. Conclusions: Skin-derived ECM hydrogels appear to be a versatile platform for investigating the function of a mechanically isolated adipose tissue stromal vascular fraction. In vitro tSVF remained viable for 10 days and sustained the expression of pro-regenerative factors, but is in need of additional triggers to induce vascularization or show signs of remodeling of the surrounding ECM. In the future, ECM-encapsulated tSVF may show promise for clinical administration to improve wound healing.

Comparing mechanical and enzymatic isolation procedures to isolate adipose-derived stromal vascular fraction: A systematic review

The stromal vascular fraction of adipose tissue has gained popularity as regenerative therapy for tissue repair. Both enzymatic and mechanical intraoperative SVF isolation procedures exist. To date, the quest for the preferred isolation procedure persists, due to the absence of standardised yield measurements and a defined clinical threshold. This systematic review is an update of the systematic review published in 2018, where guidelines were proposed to improve and standardise SVF isolation procedures. An elaborate data search in MEDLINE (PubMed), EMBASE (Ovid) and the Cochrane Central Register of Controlled Trials was conducted from September 2016 to date. A total of 26 full-text articles met inclusion criteria, evaluating 33 isolation procedures (11 enzymatic and 22 mechanical). In general, enzymatic and mechanical SVF isolation procedures yield comparable outcomes concerning cell yield (2.3-18.0 × 105 resp. 0.03-26.7 × 105 cells/ml), and cell viability (70%-99% resp. 46%-97.5%), while mechanical procedures are less time consuming (8-20 min vs. 50-210 min) and cost-efficient. However, as most studies used poorly validated outcome measures on SVF characterisation, it still remains unclear which intraoperative SVF isolation method is preferred. Future studies are recommended to implement standardised guidelines to standardise methods and improve comparability between studies.

Beneficial effects of adipose-derived stromal vascular fraction on testicular injury caused by busulfan

The use of stem cells can attenuate testicular injury and promote sperm production. The adipose-derived stromal vascular fraction (SVF) has become an attractive cell source for cell-based therapies. In this study, we aimed to investigate the therapeutic efficacy of SVF on busulfan-induced testicular damage in rats. Twenty-four male rats were randomly divided into control, busulfan, SVF, and busulfan + SVF groups. Testicular damage was induced by intraperitoneal administration of busulfan (35 mg/kg). SVF obtained from human adipose tissue using Lipocube SVF™ was injected into rats 5 weeks after busulfan administration. At the end of the 8th week, rats were sacrificed, and histopathological, biochemical, and western blotting analyses were performed. No harmful effects of SVF on healthy testis tissue and sperm parameters were detected. SVF improved busulfan-induced oxidative stress in both testis tissue and serum. SVF injection to damaged testicular tissue resulted in increases in the healthy spermatozoon numbers and decreases in the abnormal tail numbers. Additionally, SVF increased bax/Bcl, DAZL, and TGF-β1 levels whereas decreased ATG5 and NF-kB levels. According to the results we obtained in this study, we suggest that SVF is beneficial in restoring damaged tissue by primarily being a multipotent cell source, by inhibiting oxidative stress and converting necrotic cell death to apoptotic cell death. In the future, clinical applications should bring higher benefits. Since SVF is the patient's own tissue, being harmless, it will offer an advantageous supportive treatment option for patients already weakened by cancer and anticancer therapy.

Retrospective evaluation of the short-term effectiveness of non-enzymatically isolated stromal vascular fraction cells in patients with knee osteoarthritis

Background

Knee osteoarthritis (KOA) is the most common degenerative joint disease. Adipose-derived stromal vascular fraction cell therapy slows the progression of knee osteoarthritis and prevents hyaline cartilage degeneration without serious side effects. This study aims to present retrospectively the effectiveness of stromal vascular fraction cells isolated from adipose tissue by the non-enzymatic method applied to 55 osteoarthritis patients of different age groups and Kellgren-Lawrence grades on the recovery of the disease.

Material and Methods

Fifty-five patients with knee osteoarthritis, treated with stromal vascular fraction cells at the International Medical Centre (Azerbaijan) between 2020 and 2021, were included in the study to be evaluated retrospectively. Patients aged 32–67 years, Grades I–IV according to Kellgren-Lawrence classification, were included in this study. Pain and functional limitations were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires before treatment, at the 5th month, and 12th month after stromal vascular fraction injection.

Results

At the fifth and 12th months post-treatment, it was observed that the WOMAC scores were significantly improved compared with pre-treatment scores. It was also observed that stromal vascular fraction therapy was effective for Kellgren-Lawrence Grades I and II at 12 months. The most significant decrease in the WOMAC score after stromal vascular fraction treatment was observed in patients aged 45–60 years, and it was also found that there was no meaningful relationship between stromal vascular fraction efficiency and gender.

Conclusion

According to our results, non-enzymatically stromal vascular fraction treatment is more effective for longer in osteoarthritis patients with early age and low Kellgren-Lawrence grades (I and II). Moreover, our finding is that the stromal vascular fraction cells could be used safely in osteoarthritis treatments and significantly benefit patients’ quality of life.

Therapeutic application of adipose-derived stromal vascular fraction in myocardial infarction

The insufficiency of natural regeneration processes in higher organisms, including humans, underlies myocardial infarction (MI), which is one of the main causes of disability and mortality in the population of developed countries. The solution to this problem lies in the field of revealing the mechanisms of regeneration and creating on this basis new technologies for stimulating endogenous regenerative processes or replacing lost parts of tissues and organs with transplanted cells. Of great interest is the use of the so-called stromal vascular fraction (SVF), derived from autologous adipose tissue. It is known that the main functions of SVF are angiogenetic, antiapoptotic, antifibrotic, immune regulation, anti-inflammatory, and trophic. This study presents data on the possibility of using SVF, targeted regulation of its properties and reparative potential, as well as the results of research studies on its use for the restoration of damaged ischemic tissue after MI.

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.

Clinical Outcome of Minimally Manipulated, Mechanically Isolated Autologous Adipose Tissue-Derived Stromal Vascular Fraction (Sahaj Therapy®) in Knee Osteoarthritis-Randomized Controlled Trial

Introduction

Regenerative therapy has shown promising results in the treatment of osteoarthritis (OA) knee with Kellgren-Lawrence (KL) Grades I-III. We compared the safety, efficacy, functional, and clinical outcomes of intra-articular implantation of autologous adipose tissue-derived stromal vascular fraction (SVF) isolated using direct ultrasonic cavitation (Sahaj therapy-Cell Innovation Patented Technology) and saline injection in knee osteoarthritis.

Materials and Methods

The present prospective observational study was conducted over 3 years. We enrolled 120 patients in our study, where four patients got excluded as they did not meet the inclusion criteria. The remaining 116 patients were randomized into two groups, one with autologous adipose tissue-derived SVF and the other group with saline injection. A comparison of mean KOOS and VAS scores at different follow-ups was done using Paired 't' test. A p value of < 0.05 was considered significant.

Results

The results show that the SVF group had significantly higher KOOS scores (78.49 ± 6.54 in the SVF group vs 59.19 ± 5.14 in the saline group), respectively (p < 0.001). Similarly, the SVF group had significantly lesser VAS scores (3.17 ± 0.94 in the SVF group vs 3.89 ± 1.04 in the saline group), respectively (p < 0.001).

Conclusions

Autologous adipose tissue-derived SVF is a better choice for treating knee osteoarthritis. For individuals with degenerative osteoarthritis, autologous SVF grafting in the same surgical procedure is an innovative and promising treatment modality. Even after 3 years of follow-up, the study participants with OA knee have shown a good clinical and functional outcome.

Platelet-Rich stroma from Crohn's disease patients for treatment of perianal fistula shows a higher myeloid cell profile compared to non-IBD controls

BACKGROUND

New cell-based therapies are under investigation to improve perianal fistulizing Crohn's disease (pCD) healing. Autologous stromal vascular fraction combined with platelet-rich plasma (referred to as platelet-rich stroma [PRS]) is a new adipose-derived stromal therapy. The effect of Crohn's disease (CD) on adipose tissue, and adipose-derived therapies, is largely unknown. We characterized the cellular composition of subcutaneous lipoaspirate and PRS of pCD patients and non-Inflammatory Bowel Disease (IBD) controls.

METHODS

Consecutive pCD patients (≥18 years) and non-IBD controls, who underwent liposuction for the purpose of autologous PRS therapy, were included (October 2020 and March 2021). Mechanically fractionated lipoaspirate and the combined PRS product were analyzed for cell surface marker expression using fluorescence-activated cell sorting analysis.

RESULTS

Twenty-three patients (37.8 [IQR 30.7-45.0] years; 9 [39.1 %] male; 11CD patients) were included. Similar total number of cells were found in CD and non-IBD lipoaspirate (CD 8.23 ± 1.62*10⁵ cells/mL versus non-IBD 12.20 ± 3.39*10⁵). Presence of stromal cells, endothelial like cells, immune cells, T-cells, myeloid cells and M2/M1 macrophage ratio were similar in CD and non-IBD lipoaspirate. In PRS samples, more cells/mL were seen in CD patients (P = 0.030). Myeloid cells were more abundant in CD PRS samples (P = 0.007), and appeared to have a higher regulatory M2/M1 ratio. Interdonor variation was observed between lipoaspirate and PRS samples.

CONCLUSIONS

The composition of CD and non-IBD lipoaspirate were found to be similar and interdonor variation was observed. However, PRS from CD patients showed more myeloid cells with a regulatory phenotype. Crohn's disease does not appear to alter the immunological composition of adipose-derived products.

Autologous Adipose-Derived Tissue Stromal Vascular Fraction (AD-tSVF) for Knee Osteoarthritis

Adipose tissue contains adult mesenchymal stem cells that may modulate the metabolism when applied to other tissues. Stromal vascular fraction (SVF) can be isolated from adipose tissue mechanically and/or enzymatically. SVF was recently used to decrease the pain and improve the function of knee osteoarthritis (OA) patients. Primary and/or secondary OA causes inflammation and degeneration in joints, and regenerative approaches that may modify the natural course of the disease are limited. SVF may modulate inflammation and initiate regeneration in joint tissues by initiating a paracrine effect. Chemokines released from SVF may slow down degeneration and stimulate regeneration in joints. In this review, we overviewed articular joint cartilage structures and functions, OA, and macro-, micro-, and nano-fat isolation techniques. Mechanic and enzymatic SVF processing techniques were summarized. Clinical outcomes of adipose tissue derived tissue SVF (AD-tSVF) were evaluated. Medical devices that can mechanically isolate AD-tSVF were listed, and publications referring to such devices were summarized. Recent review manuscripts were also systematically evaluated and included. Transferring adipose tissues and cells has its roots in plastic, reconstructive, and aesthetic surgery. Micro- and nano-fat is also transferred to other organs and tissues to stimulate regeneration as it contains regenerative cells. Minimal manipulation of the adipose tissue is recently preferred to isolate the regenerative cells without disrupting them from their natural environment. The number of patients in the follow-up studies are recently increasing. The duration of follow up is also increasing with favorable outcomes from the short- to mid-term. There are however variations for mean age and the severity of knee OA patients between studies. Positive outcomes are related to the higher number of cells in the AD-tSVF. Repetition of injections and concomitant treatments such as combining the AD-tSVF with platelet rich plasma or hyaluronan are not solidified. Good results were obtained when combined with arthroscopic debridement and micro- or nano-fracture techniques for small-sized cartilage defects. The optimum pressure applied to the tissues and cells during filtration and purification of the AD-tSVF is not specified yet. Quantitative monitoring of articular joint cartilage regeneration by ultrasound, MR, and synovial fluid analysis as well as with second-look arthroscopy could improve our current knowledge on AD-tSVF treatment in knee OA. AD-tSVF isolation techniques and technologies have the potential to improve knee OA treatment. The duration of centrifugation, filtration, washing, and purification should however be standardized. Using gravity-only for isolation and filtration could be a reasonable approach to avoid possible complications of other methodologies.

Viewing stromal vascular fraction de novo vessel formation and association with host microvasculature using the rat mesentery culture model

OBJECTIVE

The objective of the study is to demonstrate the innovation and utility of mesenteric tissue culture for discovering the microvascular growth dynamics associated with adipose-derived stromal vascular fraction (SVF) transplantation. Understanding how SVF cells contribute to de novo vessel growth (i.e., neovascularization) and host network angiogenesis motivates the need to make observations at single-cell and network levels within a tissue.

METHODS

Stromal vascular fraction was isolated from the inguinal adipose of adult male Wistar rats, labeled with DiI, and seeded onto adult Wistar rat mesentery tissues. Tissues were then cultured in MEM + 10% FBS for 3 days and labeled for BSI-lectin to identify vessels. Alternatively, SVF and tissues from green fluorescent-positive (GFP) Sprague Dawley rats were used to track SVF derived versus host vasculature.

RESULTS

Stromal vascular fraction-treated tissues displayed a dramatically increased vascularized area compared to untreated tissues. DiI and GFP+ tracking of SVF identified neovascularization involving initial segment formation, radial outgrowth from central hub-like structures, and connection of segments. Neovascularization was also supported by the formation of segments in previously avascular areas. New segments characteristic of SVF neovessels contained endothelial cells and pericytes. Additionally, a subset of SVF cells displayed the ability to associate with host vessels and the presence of SVF increased host network angiogenesis.

CONCLUSIONS

The results showcase the use of the rat mesentery culture model as a novel tool for elucidating SVF cell transplant dynamics and highlight the impact of model selection for visualization.

Clinical applications of adipose-derived stromal vascular fraction in veterinary practice

Adipose tissue-derived stromal vascular fraction (AdSVF) comprises a heterogeneous cell population, including the multipotent mesenchymal stem cells, hematopoietic stem cells, immune cells, endothelial cells, fibroblasts, and pericytes. As such, multipotent adipose tissue-derived mesenchymal stem cells (AdMSCs), are one of the important components of AdSVF. Commonly used techniques to harvest AdSVF involve enzymatic or non-enzymatic methods. The enzymatic method is considered to be the gold standard technique due to its higher yield. The cellular components of AdSVF can be resuspended in normal saline, platelet-rich plasma, or phosphate-buffered saline to produce a ready-to-use solution. Freshly isolated AdSVF has exhibited promising osteogenic and vasculogenic capacity. AdSVF has already been proven to possess therapeutic potential for osteoarthritis management. It is also an attractive therapeutic option for enhancing wound healing. In addition, the combined use of AdSVF and platelet-rich plasma has an additive stimulatory effect in accelerating wound healing and can be considered an alternative to AdMSC treatment. It is also widely used for managing various orthopaedic conditions in clinical settings and has the potential for regenerating bone, cartilage, and tendons. Autologous AdSVF cells are used along with bone substitutes and other biological factors as an alternative to conventional bone grafting techniques owing to their promising osteogenic and vasculogenic capacity. It can also be used for treating osteonecrosis, meniscus tear, chondromalacia, and tendon injuries in veterinary practice. It has several advantages over in vitro expanded AdMSC, including precluding the need for culturing, reduced risk of cell contamination, and cost-effectiveness, making it ideal for clinical use.

Osteogenic Induction with Silicon Hydroxyapatite Using Modified Autologous Adipose Tissue-Derived Stromal Vascular Fraction: In Vitro and Qualitative Histomorphometric Analysis

Large bone defects requiring invasive surgical procedures have long been a problem for orthopedic surgeons. Despite the use of autologous bone grafting, satisfactory results are often not achieved due to associated limitations. Biomaterials are viable alternatives and have lately been used in association with Stromal Vascular Fraction (SVF), stem cells, and signaling factors for bone tissue engineering (BTE). The objective of the current study was to assess the biocompatibility of Silicon Hydroxyapatite (Si-HA) and to improve osteogenic potential by using autologous adipose-derived SVF with Si-HA in a rabbit bone defect model. Si-HA granules synthesized using a wet precipitation method were used. They were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). A hemolysis assay was used to assess the hemolytic effects of Si-HA, while cell viability was assessed through Alamar Blue assay using MC3T3 mouse osteoblasts. The osteogenic potential of Si-HA both alone and with enzymatically/non-enzymatically-derived SVF (modified) was performed by implantation in a rabbit tibia model followed by histomorphometric analysis and SEM of dissected bone after six weeks. The results showed that Si-HA granules were microporous and phase pure and that the addition of Silicon did not influence Si-HA phase composition. Si-HA granules were found to be non-hemolytic on the hemolysis assay and non-toxic to MC3T3 mouse osteoblasts on the Alamar Blue assay. Six weeks following implantation Si-HA showed high biocompatibility, with increased bone formation in all groups compared to control. Histologically more mature bone was formed in the Si-HA implanted along with non-enzymatically-derived modified SVF. Bone formation was observed on and around Si-HA, reflecting osseointegration. In conclusion, Si-HA is osteoconductive and promotes osteogenesis, and its use with SVF enhances osteogenesis.

Translational products of adipose tissue-derived mesenchymal stem cells: Bench to bedside applications

With developments in the field of tissue engineering and regenerative medicine, the use of biological products for the treatment of various disorders has come into the limelight among researchers and clinicians. Among all the available biological tissues, research and exploration of adipose tissue have become more robust. Adipose tissue engineering aims to develop by-products and their substitutes for their regenerative and immunomodulatory potential. The use of biodegradable scaffolds along with adipose tissue products has a major role in cellular growth, proliferation, and differentiation. Adipose tissue, apart from being the powerhouse of energy storage, also functions as the largest endocrine organ, with the release of various adipokines. The progenitor cells among the heterogeneous population in the adipose tissue are of paramount importance as they determine the capacity of regeneration of these tissues. The results of adipose-derived stem-cell assisted fat grafting to provide numerous growth factors and adipokines that improve vasculogenesis, fat graft integration, and survival within the recipient tissue and promote the regeneration of tissue are promising. Adipose tissue gives rise to various by-products upon processing. This article highlights the significance and the usage of various adipose tissue by-products, their individual characteristics, and their clinical applications.

Efficacy and safety of autologous adipose-derived stromal vascular fraction enriched with platelet-rich plasma in flap repair of transsphincteric cryptoglandular fistulas

Background

Transanal advancement flap repair of transsphincteric fistulas is a sphincter-preserving procedure, which frequently fails, probably due to ongoing inflammation in the remaining fistula tract. Adipose-derived stromal vascular fraction (SVF) has immunomodulatory properties promoting wound healing and suppressing inflammation. Platelet-rich plasma (PRP) reinforces this biological effect. The aim of this study was to evaluate the efficacy and safety of autologous adipose-derived SVF enriched with PRP in flap repair of transsphincteric cryptoglandular fistulas.

Methods

A prospective cohort study was conducted including consecutive patients with transsphincteric cryptoglandular fistula in a tertiary referral center. During flap repair, SVF was obtained by lipoharvesting and mechanical fractionation of adipose tissue and combined with PRP was injected around the internal opening and into the fistulous wall. Endpoints were fistula healing at clinical examination and fistula closure on postoperative magnetic resonance imaging (MRI). Adverse events were documented.

Results

Forty-five patients with transsphincteric cryptoglandular fistula were included (29 males, median age 44 years [range 36–53 years]). In the total study population, primary fistula healing was observed in 38 patients (84%). Among the 42 patients with intestinal continuity at time of surgery, primary fistula healing was observed in 35 patients (84%). In one patient, the fistula recurred, resulting in a long-term healing rate of 82%. MRI, performed in 37 patients, revealed complete closure of the fistula tract in 33 (89.2%). In the other patients, the tract was almost completely obliterated by scar tissue. During follow-up, none of these patients showed clinical signs of recurrence. The postoperative course was uneventful, except for three cases; venous thromboembolism in one patient and bleeding under the flap, necessitating intervention in two patients.

Conclusions

Addition of autologous SVF enriched with PRP during flap repair is feasible, safe and might improve outcomes in patients with a transsphincteric cryptoglandular fistula.

Trial registration

Dutch Trial Register, Trial Number: NL8416, https://www.trialregister.nl/

A systematic review of autologous adipose-derived stromal vascular fraction (SVF) for the treatment of acute cutaneous wounds

BACKGROUND

Stromal vascular fraction (SVF), derived enzymatically or mechanically from adipose tissue, contains a heterogenous population of cells and stroma, including multipotent stem cells. The regenerative capacity of SVF may potentially be adapted for a broad range of clinical applications, including the healing of acute cutaneous wounds.

OBJECTIVE

To evaluate the available literature on the efficacy and safety of autologous adipose-derived stromal vascular fraction (SVF) for the treatment of acute cutaneous wounds in humans.

METHODS

A systematic review of the literature utilizing MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials was performed to identify published clinical trials of autologous adipose-derived SVF or similar ADSC-containing derivatives for patients with acute cutaneous wounds. This was supplemented by searches for ongoing clinical trials through ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform.

RESULTS

872 records were initially retrieved. Application of inclusion and exclusion criteria yielded 10 relevant studies: two completed non-randomized controlled trials and eight ongoing clinical trials. Both completed studies reported a statistically significant benefit in percentage re-epithelialization and time to healing for the SVF treatment arms. Safety information for SVF was not provided. Ongoing clinical trials were assessing outcomes such as safety, patient and observer reported scar appearance, wound healing rate, and wound epithelization.

CONCLUSION

In the context of substantial limitations in the quantity and quality of available evidence, the existing literature suggests that SVF may be a useful treatment for acute cutaneous wounds in humans. More clinical trials with improved outcome measures and safety assessment are needed.

Mechanical Vibration-Extracted Stromal Vascular Fraction Improves Volume Retention after Autologous Fat Grafting

BACKGROUND

The stromal vascular fraction can improve volume retention after fat grafting, but the optimal stromal vascular fraction extraction method remains controversial. This study investigated the effect of mechanical vibration on stromal vascular fraction activity and explored the efficacy of vibration as a new extraction method compared to centrifugation, enzyme digestion, and nanoemulsion methods.

METHODS

Twenty-four rabbits were divided into three groups, and adipose tissue was harvested from the scapular region of each rabbit. In the first group, stromal vascular fraction was extracted from adipose tissue by vibration with different frequencies and durations. Cell counts and colony formation were assessed to determine the optimal vibration parameters. In the second group, stromal vascular fraction was extracted by the four methods, and the cell counts, proliferation, and adipogenic capabilities were observed in vitro. In the third group, adipose tissue mixed with stromal vascular fraction extracted by means of the four methods was grafted into rabbit ears. Volume retention and histologic changes were evaluated over 24 weeks.

RESULTS

Stromal vascular fraction activity was not influenced by low-frequency (≤45 Hz) and short-duration (≤20 minutes) vibrations. Vibration at 30 Hz for 15 minutes was most efficient for stromal vascular fraction extraction. In vitro, stromal vascular fraction extracted by vibration showed advantages for cell viability. In vivo, the vibration group showed a more normal tissue morphology and a higher retention rate (60.68 ± 7.07 percent) than the enzyme digestion (31.88 ± 4.99 percent), centrifugation (43.76 ± 4.32 percent), and nanoemulsion groups (21.79 ± 3.57 percent) (p < 0.05).

CONCLUSION

Vibration at 30 Hz for 15 minutes is recommended as a novel nonenzymatic method to extract stromal vascular fraction with high activity.

A clinical perspective on adipose-derived cell therapy for enhancing microvascular health and function: Implications and applications for reconstructive surgery

Restoration of form and function requires apposition of tissues in the form of flaps to reconstitute local perfusion. Successful reconstruction relies on flap survival and its integration with the recipient bed. The flap's precariously perfused hypoxic areas undergo adaptive microvascular changes both internally and in connection with the recipient bed. A cell-mediated, coordinated response to hypoxia drives these adaptive processes, restoring a tissue's normoxic homeostasis via de novo vasculogenesis, sprouting angiogenesis, and stabilizing arterialization. As cells exert prolonged and coordinated effects on site, their use as biological agents merit translational consideration of sourcing angio-competent cells and delivering them to territories enduring microcirculatory acclimatization. Angio-competent cells abound in adipose tissue: a reliable, accessible, and expendable source of adipose-derived cells (ADC). When subject to enzymatic digestion and centrifugation, adipose tissue separates its various ADC: A subset of buoyant oil-dense adipocytes (the tissue's parenchymal component) accumulates on a supra-natant layer, whereas the mesenchymal component remains in the infra-natant sediment, containing the tissue's stromal vascular fraction (SVF), where angio-component cells abound. The SVF can be further manipulated, selected, or culture expanded into more specific stromal subsets (herein defined as adipose stromal cells, ASC). While promising clinical applications for ADC await clinical proof and regulatory authorization, basic science investigation is needed to elucidate the specific ADC mechanisms that influence microvascular growth, remodeling, and function following flap surgery. The objective of this article is to share the clinical perspectives of reconstructive plastic surgeons regarding the use of ADC-based therapies to help with flap tissue integration, revascularization, and wound healing. Specifically, the focus will be on considering the potential for ADC as therapeutic agents and how their clinical application motivates basic science opportunities.