Shift toward Mechanical Isolation of Adipose-derived Stromal Vascular Fraction: Review of Upcoming Techniques

Engineered stromal vascular fraction for tissue regeneration

The treatment of various tissue injuries presents significant challenges, particularly in the reconstruction of large and severe tissue defects, with conventional clinical methods often yielding suboptimal results. However, advances in engineering materials have introduced new possibilities for tissue repair. Bioactive components are commonly integrated with synthetic materials to enhance tissue reconstruction. Stromal vascular fraction (SVF), an adipose-derived cell cluster, has shown considerable potential in tissue regeneration due to its simple and efficient way of obtaining and its richness in growth factors. Therefore, this review illustrated the preparation, characterization, mechanism of action, and applications of engineered SVF in various tissue repair processes, to provide some references for the option of better methods for tissue defect reconstruction.

Revisiting Fat Graft Harvesting and Processing Technique to Optimize Its Regenerative Potential

Background

The use of fat grafting has expanded to include cell and tissue regeneration, necessitating investigations to ensure the viability of stromal and adipose-derived mesenchymal stem cells (ASCs) within the transferred fat parcels. This study explored the impact of harvesting technique and centrifugation on the viability of stromal cells and ASCs in lipoaspirate.

Methods

Fat was harvested from patients undergoing fat grafting using 2 types of liposuction cannula: (A) a 3-mm blunt tip cannula with 3 smooth holes and (B) a 2.4-mm, sharp point port, multihole blunt tip cannula. Fat from cannula B underwent different processing methods: no centrifugation, 300g, 600g, and 900g centrifugation. Stromal cells were isolated, quantified, and evaluated for viability. ASCs were cultured from these samples to confirm survival.

Results

Lipoaspirates from 21 patients were analyzed. The mean stromal cell counts were 0.937 × 109 ± 0.346 × 109/mL for cannula A and 0.734 × 109 ± 0.266 × 109/mL for cannula B (P = 0.684), with viabilities of 98.79% and 98.22% (P = 0.631), respectively. ASCs isolated and after 2-passage culture were also higher for cannula A. Stromal cell quantification and viability were lowest in the noncentrifuged group (P < 0.05) and highest in the 600g centrifugation group.

Conclusions

Fat harvesting using cannulas A and B showed no significant difference in stromal cell yield or viability. Handheld syringe liposuction preserved stromal vascular fraction cell and ASC viability. Centrifugation at different speeds did not significantly affect stromal cell viability.

Current Non-Surgical Curative Regenerative Therapies for Knee Osteoarthritis

Osteoarthritis (OA) is a prevalent musculoskeletal disease affecting middle-aged and elderly individuals, with knee pain as a common complaint. Standard therapy approaches generally attempt to alleviate pain and inflammation, using various pharmacological and non-pharmacological options. However, the efficacy of these therapies in long-term tissue repair remains debated. As an alternative, regenerative medicine offers a promising strategy, with decreased adverse event rates and increasing evidence of safety and efficacy. This review will outline current advances in regenerative medicine for knee OA, emphasizing outpatient clinic-based therapies that use orthobiological and non-biological products. Different strategies based on orthobiologics are discussed as potential regenerative options for the management of knee OA. Cell-free therapies including platelet-rich plasma, autologous anti-inflammatories, exosomes, human placenta extract, and mitochondrial transplantation are discussed, focusing on their potential for cartilage regeneration. Additionally, cell-based therapies with regenerative properties including bone marrow aspirate concentrate, adipose stromal vascular fraction, microfat, nanofat, stem cell therapy, and genetically modified cells as part of orthobiologics, are being investigated. Also, this study is looking into non-biological approaches such as using gold-induced cytokines, extracorporeal shockwave therapy, and ozone therapy. The mechanisms of action, effectiveness, and clinical applications of each therapy are being explored, providing insights into their role in the management of knee OA.

Evaluating the Efficacy of Facial Scar Treatment Techniques Using Nanofat Grafting: A Case Series

Patient's psychological and aesthetic quality is affected by the appearance of scars since atrophic scars might be caused by infections or inflammations that resulted from preoperative procedures. Non-surgical methods have recently been developed to increase patient satisfaction and improve the appearance of scars. In our understanding, there has not been much published medical research assessing how well nanofat grafting techniques work in terms of treating facial scars. With a six-month follow-up after the intervention, this research intends to provide four cases where scars in the facial area were controlled utilizing these materials. Based on the cases shown, it can be seen that following the procedure, the scar's measurements were minimized, its color and texture improved, and there was no pain or itching. Given its safety and effectiveness, autologous nanofat grafting has become one of the most important and well-liked aesthetic procedures. It has been discussed how modifying injectable nanofat using fine needles has opened up new clinical applications for rejuvenating aesthetic medicine. Additionally, it was pointed out that injectable PRF has gained attention due to its high concentration of growth factors, which help to promote healing and improve the appearance of the skin. Furthermore, it can be efficiently shared with autogenous nanofat grafts, which support and enhance the efficacy of adipose-derived stem cells (ADSCs) and improve adipocyte blood circulation. The current use of modified nanofat in the treatment of facial scars is supported by the procedure's safety and low risk of injection-site problems. The consistent efficacy of modified-nanofat injection in the management of depression-related facial scars was validated by the outcomes of patient satisfaction surveys and physician evaluations.

Evaluating Stromal Vascular Fraction As a Treatment for Peripheral Nerve Regeneration: A Scoping Review

PURPOSE

This study aims to investigate the potential of stromal vascular fraction (SVF) for peripheral nerve regeneration.

METHODS

A scoping review of Scopus and PubMed databases was conducted. Inclusion criteria were human or animal studies exploring the use of SVF for peripheral nerve regeneration. Studies were categorized by assessed outcomes: pain assessment, neural integrity, muscle recovery, and functional recovery. Level of evidence and study quality were assessed.

RESULTS

Nine studies met the inclusion criteria. SVF injection in humans with trigeminal neuropathic pain reduced pain scores from 7.5 ± 1.58 to 4.3 ± 3.28. SVF injection improved sensation in humans with leprosy neuropathy. Repairing transected rat sciatic nerves with SVF-coated nerve autografts improved wet muscle weight ratios (0.65 ± 0.11 vs 0.55 ± 0.06) and sciatic functional index (SFI) scores (-68.2 ± 9.2 vs -72.5 ± 8.9). Repairing transected rat sciatic nerves with SVF-coated conduits increased the ratio of gastrocnemius muscle weights (RGMW) (7-10% improvement), myelinated fibers (1,605 ± 806.2 vs 543.6 ± 478.66), and myelin thickness (5-20% increase). Repairing transected rat facial nerves with SVF-coated conduits improved whisker motion (9.22° ± 0.65° vs 1.90° ± 0.84°) and myelin thickness (0.57 μm ± 0.17 vs 0.45 μm ± 0.14 μm). Repairing transected rat sciatic nerves with SVF-coated nerve allografts improved RGMW (85 vs 50%), SFI scores (-20 to -10 vs -40 to -30), and Basso, Beatie, and Bresnahan locomotor scores (18 vs 15). All metrics mentioned above were statistically significant. The human studies were level 4 evidence due to being case series, while animal studies were the lowest level of evidence.

CONCLUSION

Despite initial promising results, the low-level evidence from the included studies warrants further investigation.

Role of Adipose-Derived Mesenchymal Stem Cells in Bone Regeneration

Bone regeneration involves multiple factors such as tissue interactions, an inflammatory response, and vessel formation. In the event of diseases, old age, lifestyle, or trauma, bone regeneration can be impaired which could result in a prolonged healing duration or requiring an external intervention for repair. Currently, bone grafts hold the golden standard for bone regeneration. However, several limitations hinder its clinical applications, e.g., donor site morbidity, an insufficient tissue volume, and uncertain post-operative outcomes. Bone tissue engineering, involving stem cells seeded onto scaffolds, has thus been a promising treatment alternative for bone regeneration. Adipose-derived mesenchymal stem cells (AD-MSCs) are known to hold therapeutic value for the treatment of various clinical conditions and have displayed feasibility and significant effectiveness due to their ease of isolation, non-invasive, abundance in quantity, and osteogenic capacity. Notably, in vitro studies showed AD-MSCs holding a high proliferation capacity, multi-differentiation potential through the release of a variety of factors, and extracellular vesicles, allowing them to repair damaged tissues. In vivo and clinical studies showed AD-MSCs favoring better vascularization and the integration of the scaffolds, while the presence of scaffolds has enhanced the osteogenesis potential of AD-MSCs, thus yielding optimal bone formation outcomes. Effective bone regeneration requires the interplay of both AD-MSCs and scaffolds (material, pore size) to improve the osteogenic and vasculogenic capacity. This review presents the advances and applications of AD-MSCs for bone regeneration and bone tissue engineering, focusing on the in vitro, in vivo, and clinical studies involving AD-MSCs for bone tissue engineering.

A Simple and Effective Mechanical Method for Adipose-Derived Stromal Vascular Fraction Isolation

Over the last decades, there has been ongoing and evolving research concerning regenerative medicine, specifically, stem cells. The most common source of adult mesenchymal stem cells (MSCs) remains the adipose tissue and the easiest way to obtain such tissue is lipoaspirate. The fatty tissue obtained can be processed either in an enzymatic way, which is time-consuming and expensive and carries several dangers for the viability of the stem cells included, or with mechanical means which are fast, inexpensive, yield enough viable cells, and can be readily used for autologous transplantation in one-stage procedures. Herein, we demonstrate our non-enzymatic method for obtaining adipose-derived stromal vascular fraction comprising MSCs. The stromal vascular fraction was isolated via centrifugation, and the characteristics and numbers of the cells isolated have been tested with flow cytometry assay, cell culture, and differentiation. Over 91% of viable MSCs were isolated using the mechanical method. The cells retained the ability to differentiate into osteocytes, adipocytes, and chondrocytes. The method presented is simple, requiring no special equipment, and yields a viable population of stem cells in large numbers. These cells can be readily used in several operations (orthopedic, dentistry, fistulas, etc.) making feasible "one-stage" procedures, thus proving their benefits for the patient and the health care system.

Stromal vascular fraction in the treatment of myositis

Muscle regeneration is a physiological process that converts satellite cells into mature myotubes under the influence of an inflammatory environment progressively replaced by an anti-inflammatory environment, with precise crosstalk between immune and muscular cells. If the succession of these phases is disturbed, the immune system can sometimes become auto-reactive, leading to chronic muscular inflammatory diseases, such as myositis. The triggers of these autoimmune myopathies remain mostly unknown, but the main mechanisms of pathogenesis are partially understood. They involve chronic inflammation, which could be associated with an auto-reactive immune response, and gradually with a decrease in the regenerative capacities of the muscle, leading to its degeneration, fibrosis and vascular architecture deterioration. Immunosuppressive treatments can block the first part of the process, but sometimes muscle remains weakened, or even still deteriorates, due to the exhaustion of its capacities. For patients refractory to immunosuppressive therapies, mesenchymal stem cells have shown interesting effects but their use is limited by their availability. Stromal vascular fraction, which can easily be extracted from adipose tissue, has shown good tolerance and possible therapeutic benefits in several degenerative and autoimmune diseases. However, despite the increasing use of stromal vascular fraction, the therapeutically active components within this heterogeneous cellular product are ill-defined and the mechanisms by which this therapy might be active remain insufficiently understood. We review herein the current knowledge on the mechanisms of action of stromal vascular fraction and hypothesise on how it could potentially respond to some of the unmet treatment needs of refractory myositis.

Push-Through Filtration of Emulsified Adipose Tissue Over a 500-µm Mesh Significantly Reduces the Amount of Stromal Vascular Fraction and Mesenchymal Stem Cells

BACKGROUND

Mechanical isolation of the stromal vascular fraction (SVF) separates the stromal component from the parenchymal cells. Emulsification is currently the most commonly used disaggregation method and is effective in disrupting adipocytes and fragmenting the extracellular matrix (ECM). Subsequent push-through filtration of emulsified adipose tissue removes parts of the ECM that are not sufficiently micronized, thereby further liquifying the tissue.

OBJECTIVES

The aim of this study was to investigate whether filtration over a 500-µm mesh filter might affect the SVF and adipose-derived mesenchymal stem cell (MSC) quantity in emulsified lipoaspirate samples by removing ECM fragments.

METHODS

Eleven lipoaspirate samples from healthy nonobese women were harvested and emulsified in 30 passes. One-half of the sample was filtered through a 500-µm mesh filter and the other half was left unfiltered. Paired samples were processed and analyzed by flow cytometry to identify cellular viability, and SVF and MSC yield.

RESULTS

Push-through filtration reduced the number of SVF cells by a mean [standard deviation] of 39.65% [5.67%] (P < .01). It also significantly reduced MSC counts by 48.28% [6.72%] (P < .01). Filtration did not significantly affect viability (P = .118).

CONCLUSIONS

Retention of fibrous remnants by push-through filters removed ECM containing the SVF and MSCs from emulsified lipoaspirates. Processing methods should aim either to further micronize the lipoaspirate before filtering or not to filter the samples at all, to preserve both the cellular component carried within the ECM and the inductive properties of the ECM itself.

Alveolar Ridge Augmentation with a Novel Combination of 3D-Printed Scaffolds and Adipose-Derived Mesenchymal Stem Cells-A Pilot Study in Pigs

Alveolar ridge augmentation is an important dental procedure to increase the volume of bone tissue in the alveolar ridge before the installation of a dental implant. To meet the high demand for bone grafts for alveolar ridge augmentation and to overcome the limitations of autogenous bone, allografts, and xenografts, researchers are developing bone grafts from synthetic materials using novel fabrication techniques such as 3D printing. To improve the clinical performance of synthetic bone grafts, stem cells with osteogenic differentiation capability can be loaded into the grafts. In this pilot study, we propose a novel bone graft which combines a 3D-printed polycaprolactone-tricalcium phosphate (PCL-TCP) scaffold with adipose-derived mesenchymal stem cells (AD-MSCs) that can be harvested, processed and implanted within the alveolar ridge augmentation surgery. We evaluated the novel bone graft in a porcine lateral alveolar defect model. Radiographic analysis revealed that the addition of AD-MSCs to the PCL-TCP scaffold improved the bone volume in the defect from 18.6% to 28.7% after 3 months of healing. Histological analysis showed the presence of AD-MSCs in the PCL-TCP scaffold led to better formation of new bone and less likelihood of fibrous encapsulation of the scaffold. Our pilot study demonstrated that the loading of AD-MSCs improved the bone regeneration capability of PCL-TCP scaffolds, and our novel bone graft is suitable for alveolar ridge augmentation.

A Closed-system Technology for Mechanical Isolation of High Quantities of Stromal Vascular Fraction from Fat for Immediate Clinical Use

Adipose tissue stromal vascular fraction (SVF) is increasingly used in the clinic. SVF separation from fat by enzymatic disruption is currently the gold standard for SVF isolation. However, enzymatic SVF isolation is time-consuming (~1.5 h), costly and significantly increases the regulatory burden of SVF isolation. Mechanical fat disruption is rapid, cheaper, and less regulatory challenging. However, its reported efficacy is insufficient for clinical use. The current study evaluated the efficacy of a novel rotating blades (RBs) mechanical SVF isolation system.

Methods

SVF cells were isolated from the same lipoaspirate sample (n = 30) by enzymatic isolation, massive shaking (wash), or engine-induced RBs mechanical isolation. SVF cells were counted, characterized by flow cytometry and by their ability to form adipose-derived stromal cells (ASCs).

Results

The RBs mechanical approach yielded 2 × 10⁵ SVF nucleated cells/mL fat, inferior to enzymatic isolation (4.17 × 10⁵) but superior to cells isolating from fat by the "wash" technique (0.67 × 10⁵). Importantly, RBs SVF isolation yield was similar to reported yields achieved via clinical-grade enzymatic SVF isolation. RBs-isolated SVF cells were found to contain 22.7% CD45^-CD31^-CD34⁺ stem cell progenitor cells (n = 5) yielding quantities of multipotent ASCs similar to enzymatic controls.

Conclusions

The RBs isolation technology provided for rapid (<15 min) isolation of high-quality SVF cells in quantities similar to those obtained by enzymatic digestion. Based on the RBs platform, a closed-system medical device for SVF extraction in a rapid, simple, safe, sterile, reproducible, and cost-effective manner was designed.

Letter to the Editor: An Optimized Method for Adipose Stromal Vascular Fraction Isolation and its Application in Fat Grafting

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

Stromal vascular fraction with platelet-rich plasma injection during surgery is feasible and safe in treatment-refractory perianal fistulising Crohn's disease: A pilot study

BACKGROUND

An unmet need remains for improved management in perianal fistulising Crohn's disease (pCD). Recently, local administration of adipose-derived cells has shown promising results.

AIMS

To assess the safety and feasibility of injection of stromal vascular fraction (SVF) with platelet-rich plasma (PRP) in patients with pCD.

METHODS

Patients ≥ 18 years with pCD were included and underwent fistula curettage, SVF with PRP injection, and closure of the internal opening. The primary endpoint was safety at 12 months. The secondary outcomes were complete radiological healing at 3 months (absence of fluid-containing tracts on MRI) and partial and complete clinical response at 3 and 12 months (closure of ≥1, respectively, all treated external opening(s)).

RESULTS

Twenty-five patients were included (35 [IQR 25-40] years; 14 [56%] female); median CD duration 4 [IQR 2-8] years. Twenty-four (95%) patients had previously undergone fistula surgery. No adverse events were encountered at lipoharvesting sites. Two (8%) patients were readmitted to hospital and six (24%) underwent unplanned re-interventions. Post-operative MRI (n = 24) showed complete radiological healing in nine (37.5%) patients. Partial clinical response was present in 48% (12/25) at 3 months and in 68% (17/25) at 12 months, and complete clinical closure in five (20%) patients at 3 months and in 10 (40%) patients at 12 months.

CONCLUSION

Injection with autologous SVF with PRP is feasible and safe in patients with treatment-refractory pCD. Early complete radiological healing was observed in more than one-third of patients, and clinical response in two-thirds of patients at 12 months.

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.

Micro-fragmented and nanofat adipose tissue derivatives: In vitro qualitative and quantitative analysis

Introduction: Adipose tissue is widely exploited in regenerative medicine thanks to its trophic properties, mainly based on the presence of adipose-derived stromal cells. Numerous devices have been developed to promote its clinical use, leading to the introduction of one-step surgical procedures to obtain minimally manipulated adipose tissue derivatives. However, only a few studies compared their biological properties. This study aimed to characterize micro-fragmented (MAT) and nanofat adipose tissue (NAT) obtained with two different techniques. Methods: MAT, NAT and unprocessed lipoaspirate were collected from surgical specimens. RNA extraction and collagenase isolation of stromal vascular fraction (SVF) were performed. Tissue sections were analysed by histological and immunohistochemical (collagen type I, CD31, CD34 and PCNA) staining to assess tissue morphology and cell content. qPCR was performed to evaluate the expression of stemness-related (SOX2, NANOG and OCT3/4), extracellular matrix (COL1A1) and inflammatory genes (IL1β, IL6 and iNOS). Furthermore, multilineage differentiation was assessed following culture in adipogenic and osteogenic media and staining with Oil Red O and Alizarin red. ASC immunophenotype was assessed by flow cytometric analysis of CD90, CD105, CD73 and CD45. Results: Histological and immunohistochemical results showed an increased amount of stroma and a reduction of adipocytes in MAT and NAT, with the latter displaying the highest content of collagen type I, CD31, CD34 and PCNA. From LA to MAT and NAT, an increasing expression of NANOG, SOX2, OCT3/4, COL1A1 and IL6 was noted, while no significant differences in terms of IL1β and iNOS emerged. No statistically significant differences were noted between NAT and SVF in terms of stemness-related genes, while the latter demonstrated a significantly higher expression of stress-related markers. SVF cells derived from all three samples (LA, MAT, and NAT) showed a similar ASC immunoprofile as well as osteogenic and adipogenic differentiation. Discussion: Our results showed that both MAT and NAT techniques allowed the rapid isolation of ASC-rich grafts with a high anabolic and proliferative potential. However, NAT showed the highest levels of extracellular matrix content, replicating cells, and stemness gene expression. These results may provide precious clues for the use of adipose tissue derivatives in the clinical setting.

The Composition of Adipose-Derived Regenerative Cells Isolated from Lipoaspirate Using a Point of Care System Does Not Depend on the Subject's Individual Age, Sex, Body Mass Index and Ethnicity

Uncultured, unmodified, autologous, adipose-derived regenerative cells (UA-ADRCs) are a safe and effective treatment option for various musculoskeletal pathologies. However, it is unknown whether the composition of the final cell suspension systematically varies with the subject's individual age, sex, body mass index and ethnicity. UA-ADRCs were isolated from lipoaspirate from n = 232 subjects undergoing elective lipoplasty using the Transpose RT system (InGeneron, Inc.; Houston, TX, USA). The UA-ADRCs were assessed for the number of nucleated cells, cell viability and the number of viable nucleated cells per gram of adipose tissue harvested. Cells from n = 37 subjects were further characterized using four-channel flow cytometry. The present study shows, for the first time, that key characteristics of UA-ADRCs can be independent of the subject's age, sex, BMI and ethnicity. This result has important implications for the general applicability of UA-ADRCs in regeneration of musculoskeletal tissue. Future studies must determine whether the independence of key characteristics of UA-ADRCs of the subject's individual age, sex, BMI and ethnicity only applies to the system used in the present study, or also to others of the more than 25 different experimental methods and commercially available systems used to isolate UA-ADRCs from lipoaspirate that have been described in the literature.

High-Quality Lipoaspirate Following 1470-nm Radial Emitting Laser-Assisted Liposuction

BACKGROUND

Laser-assisted liposuction (LAL) has been used to maximize viable adipocyte yields in lipoaspirates, although optimizing tissue processing methods is still a challenge. A high-quality lipoaspirate has been a key factor for extended graft longevity.

OBJECTIVE

To assess the viability and potency of stromal vascular fraction (SVF) cells and adipose-derived stem cells (ASCs) in fat samples from lipoaspirates harvested with a novel 1470-nm diode, radial emitting LAL platform. Two processing methods, enzymatic and nonenzymatic, were compared.

METHODS

Laser-assisted liposuction lipoaspirates harvested from 10 subjects were examined for cell viability after processing by enzymatic or nonenzymatic methods. Isolated SVF cells were cultured with an ASC-permissive medium to assess their viability and proliferation capacity by cell proliferation assay. Flow cytometric analysis with ASC-specific markers, gene expression levels, and immunofluorescence for ASC transcription factors were also conducted.

RESULTS

Lipoaspirates showed high SVF cell viability of 97% ± 0.02% and 98% ± 0.01%, averaged SVF cell count of 8.7 × 10 6 ± 3.9 × 10 6 and 9.4 × 10 6 ± 4.2 × 10 6 cells per mL, and averaged ASC count of 1 × 10 6 ± 2.2 × 10 5 and 1.2 × 10 6 ± 5 × 10 5 cells per mL in nonenzymatic and enzymatic methods, respectively. The ASC-specific markers, gene expression levels, and immunofluorescence for ASC transcription factors confirmed the adipose origin of the cells.

CONCLUSIONS

The laser lipoaspirates provide a high yield of viable and potent SVF cells and ASCs through both nonenzymatic and enzymatic processes. Improved purity of the harvested lipoaspirate and high ASC content are expected to result in extended graft longevity. Furthermore, eliminating enzymatic digestion may provide advantages, such as reducing process time, cost, and regulatory constraints.

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

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

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.

Nanofat: A therapeutic paradigm in regenerative medicine

Adipose tissue is a compact and well-organized tissue containing a heterogeneous cellular population of progenitor cells, including mesenchymal stromal cells. Due to its availability and accessibility, adipose tissue is considered a “stem cell depot.” Adipose tissue products possess anti-inflammatory, anti-fibrotic, anti-apoptotic, and immunomodulatory effects. Nanofat, being a compact bundle of stem cells with regenerative and tissue remodeling potential, has potential in translational and regenerative medicine. Considering the wide range of applicability of its reconstructive and regenerative potential, the applications of nanofat can be used in various disciplines. Nanofat behaves on the line of adipose tissue-derived mesenchymal stromal cells. At the site of injury, these stromal cells initiate a site-specific reparative response comprised of remodeling of the extracellular matrix, enhanced and sustained angiogenesis, and immune system modulation. These properties of stromal cells provide a platform for the usage of regenerative medicine principles in curbing various diseases. Details about nanofat, including various preparation methods, characterization, delivery methods, evidence on practical applications, and ethical concerns are included in this review. However, appropriate guidelines and preparation protocols for its optimal use in a wide range of clinical applications have yet to be standardized.

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.

Stem Cells in Autologous Microfragmented Adipose Tissue: Current Perspectives in Osteoarthritis Disease

Osteoarthritis (OA) is a chronic debilitating disorder causing pain and gradual degeneration of weight-bearing joints with detrimental effects on cartilage volume as well as cartilage damage, generating inflammation in the joint structure. The etiology of OA is multifactorial. Currently, therapies are mainly addressing the physical and occupational aspects of osteoarthritis using pharmacologic pain treatment and/or surgery to manage the symptomatology of the disease with no specific regard to disease progression or prevention. Herein, we highlight alternative therapeutics for OA specifically considering innovative and encouraging translational methods with the use of adipose mesenchymal stem cells.

Stem Cell Therapy for Burns: Story so Far

Burn injuries affect approximately 11 million people annually, with fatalities amounting up to 180,000. Burn injuries constitute a global health issue associated with high morbidity and mortality. Recent years have seen advancements in regenerative medicine for burn wound healing encompassing stem cells and stem cell-derived products such as exosomes and conditioned media with promising results compared to current treatment approaches. Sources of stem cells used for treatment vary ranging from hair follicle stem cells, embryonic stem cells, umbilical cord stem cells, to mesenchymal stem cells, such as adipose-derived mesenchymal stem cells, bone marrow-derived mesenchymal stem cells, and even stem cells harvested from discarded burn tissue. Stem cells utilize various pathways for wound healing, such as PI3/AKT pathway, WNT-β catenin pathway, TGF-β pathway, Notch and Hedgehog signaling pathway. Due to the paracrine signaling mechanism of stem cells, exosomes and conditioned media derived from stem cells have also been utilized in burn wound therapy. As exosomes and conditioned media are cell-free therapy and contain various biomolecules that facilitate wound healing, they are gaining popularity as an alternative treatment strategy with significant improvement in outcomes. The treatment is provided either as direct injections or embedded in a natural/artificial scaffold. This paper reviews in detail the different sources of stem cells, stem cell-derived products, their efficacy in burn wound repair, associated signaling pathways and modes of delivery for wound healing.

Perspective: Why and How Ubiquitously Distributed, Vascular-Associated, Pluripotent Stem Cells in the Adult Body (vaPS Cells) Are the Next Generation of Medicine

A certain cell type can be isolated from different organs in the adult body that can differentiate into ectoderm, mesoderm, and endoderm, providing significant support for the existence of a certain type of small, vascular-associated, pluripotent stem cell ubiquitously distributed in all organs in the adult body (vaPS cells). These vaPS cells fundamentally differ from embryonic stem cells and induced pluripotent stem cells in that the latter possess the necessary genetic guidance that makes them intrinsically pluripotent. In contrast, vaPS cells do not have this intrinsic genetic guidance, but are able to differentiate into somatic cells of all three lineages under guidance of the microenvironment they are located in, independent from the original tissue or organ where they had resided. These vaPS cells are of high relevance for clinical application because they are contained in unmodified, autologous, adipose-derived regenerative cells (UA-ADRCs). The latter can be obtained from and re-applied to the same patient at the point of care, without the need for further processing, manipulation, and culturing. These findings as well as various clinical examples presented in this paper demonstrate the potential of UA-ADRCs for enabling an entirely new generation of medicine for the benefit of patients and healthcare systems.

Injections in the osteoarthritic knee: a review of current treatment options

Knee osteoarthritis is a degenerative condition characterized by progressive cartilage degradation, subchondral damage, and bone remodelling. Among the approaches implemented to achieve symptomatic and functional improvements, injection treatments have gained increasing attention due to the possibility of intra-articular delivery with reduced side effects compared to systemic therapies.

In addition to well-established treatment options such as hyaluronic acid (HA), cortico-steroids (CS) and oxygen-ozone therapy, many other promising products have been employed in the last decades such as polydeoxyribonucleotide (PDRN) and biologic agents such as platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs). Moreover, ultrasound-guided intra-meniscal injection and X-ray-guided subchondral injection techniques have been introduced into clinical practice.

Even when not supported by high evidence consensus, intra-articular CS and HA injections have gained precise indications for symptomatic relief and clinical improvement in OA. Biological products are strongly supported by in vitro evidence but there is still a lack of robust clinical evidence. PRP and MSCs seem to relieve OA symptoms through a regulation of the joint homeostasis, even if their capability to restore articular cartilage is still to be proved in vivo.

Due to increasing interest in the subchondral bone pathology, subchondral injections have been developed with promising results in delaying joint replacement. Nevertheless, due to their recent development and the heterogeneity of the injected products (biologic agents or calcium phosphate), this approach still lacks strong enough evidence to be fully endorsed.

Combined biological treatments, nano-molecular approaches, monoclonal antibodies and ‘personalized’ target therapies are currently under development or under investigation with the aim of expanding our armamentarium against knee OA.

Cite this article: EFORT Open Rev 2021;6:501-509. DOI: 10.1302/2058-5241.6.210026

Jaw Periosteum-Derived Mesenchymal Stem Cells Regulate THP-1-Derived Macrophage Polarization

Mesenchymal stem cells from bone marrow have powerful immunomodulatory capabilities. The interactions between jaw periosteal cells (JPCs) and macrophages are not only relevant for the application of JPCs in regenerative medicine, but this understanding could also help treating diseases like osteonecrosis of the jaw. In previous studies, we analyzed, for the first time, immunomodulatory features of 2D- and 3D-cultured JPCs. In the present work, the effects of JPCs on the polarization state of macrophages in contact coculture were analyzed. To improve the macrophage polarization study, different concentrations of PMA (5 nM, 25 nM, and 150 nM) or different medium supplementations (10% FBS, 10% hPL and 5% hPL) were compared. Further, in order to analyze the effects of JPCs on macrophage polarization, JPCs and PMA-stimulated THP-1 cells were cocultured under LPS/IFN-γ or IL-4/IL-13 stimulatory conditions. Surface marker expression of M1 and M2 macrophages were analyzed under the different culture supplementations in order to investigate the immunomodulatory properties of JPCs. Our results showed that 5 nM PMA can conduct an effective macrophage polarization. The analyses of morphological parameters and surface marker expression showed more distinct M1/M2 phenotypes over FBS supplementation when using 5% hPL during macrophage polarization. In the coculture, immunomodulatory properties of JPCs improved significantly under 5% hPL supplementation compared to other supplementations. We concluded that, under the culture condition with 5% hPL, JPCs were able to effectively induce THP-1-derived macrophage polarization.

Water jet-assisted lipoaspiration and Sepax cell separation system for the isolation of adipose stem cells with high adipogenic potential

INTRODUCTION

Water jet-assisted liposuction has gained popularity due to favourable fat grafting outcomes. In this study, we compared stem cells obtained from fat isolated with manual or the water jet-assisted procedure.

METHODS

Liposuction of abdominal fat was performed using the two methods on each donor (n = 10). Aspirate samples were collagenase digested and the isolated cells seeded in vitro prior to proliferation, adipogenic differentiation and angiogenic activity analyses.

RESULTS

Cells from either procedure proliferated at similar rates and exhibited a similar colony-forming ability. The cells expressed stem cell markers CD73, CD90 and CD105. In the water jet cell preparations, there were higher numbers of cells expressing CD146. Robust adipogenic differentiation was observed in cultures expanded from both manual and water jet lipoaspirates. Gene analysis showed higher expression of the adipocyte markers aP2 and GLUT4 in the adipocyte-differentiated water jet cell preparations, and ELISA indicated increased secretion of adiponectin from these cells. Both cell groups expressed vasculogenic factors and the water jet cells promoted the highest levels of in vitro angiogenesis. Given these positive results, we further characterised the water jet cells when prepared using an automated closed cell processing unit, the Sepax-2 system (Cytiva). The growth and stem cell properties of the Sepax-processed cells were similar to the standard centrifugation protocol, but there was evidence for greater adipogenic differentiation in the Sepax-processed cells.

CONCLUSIONS

Water jet lipoaspirates yield cells with high adipogenic potential and angiogenic activity, which may be beneficial for use in cell-assisted lipotransfers.

Human Platelet Lysate Acts Synergistically With Laminin to Improve the Neurotrophic Effect of Human Adipose-Derived Stem Cells on Primary Neurons in vitro

Background

Despite the advancements in microsurgical techniques and noteworthy research in the last decade, peripheral nerve lesions have still weak functional outcomes in current clinical practice. However, cell transplantation of human adipose-derived stem cells (hADSC) in a bioengineered conduit has shown promising results in animal studies. Human platelet lysate (hPL) has been adopted to avoid fetal bovine serum (FBS) in consideration of the biosafety concerns inherent with the use of animal-derived products in tissue processing and cell culture steps for translational purposes. In this work, we investigate how the interplay between hPL-expanded hADSC (hADSC^hPL) and extracellular matrix (ECM) proteins influences key elements of nerve regeneration.

Methods

hADSC were seeded on different ECM coatings (laminin, LN; fibronectin, FN) in hPL (or FBS)-supplemented medium and co-cultured with primary dorsal root ganglion (DRG) to establish the intrinsic effects of cell–ECM contact on neural outgrowth. Co-cultures were performed “direct,” where neural cells were seeded in contact with hADSC expanded on ECM-coated substrates (contact effect), or “indirect,” where DRG was treated with their conditioned medium (secretome effect). Brain-derived nerve factor (BDNF) levels were quantified. Tissue culture plastic (TCPS) was used as the control substrate in all the experiments.

Results

hPL as supplement alone did not promote higher neurite elongation than FBS when combined with DRG on ECM substrates. However, in the presence of hADSC, hPL could dramatically enhance the stem cell effect with increased DRG neurite outgrowth when compared with FBS conditions, regardless of the ECM coating (in both indirect and direct co-cultures). The role of ECM substrates in influencing neurite outgrowth was less evident in the FBS conditions, while it was significantly amplified in the presence of hPL, showing better neural elongation in LN conditions when compared with FN and TCPS. Concerning hADSC growth factor secretion, ELISA showed significantly higher concentrations of BDNF when cells were expanded in hPL compared with FBS-added medium, without significant differences between cells cultured on the different ECM substrates.

Conclusion

The data suggest how hADSC grown on LN and supplemented with hPL could be active and prone to support neuron–matrix interactions. hPL enhanced hADSC effects by increasing both proliferation and neurotrophic properties, including BDNF release.

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.

In-Vitro Comparative Examination of the Effect of Stromal Vascular Fraction Isolated by Mechanical and Enzymatic Methods on Wound Healing

BACKGROUND

Enzymatic digestion has been the gold standard for stromal vascular fraction (SVF) isolation but remains expensive and raises practical and legal concerns. Mechanical SVF isolation methods have been known to produce lower cell yields, but may potentially produce a more robust product by preserving the extracellular matrix niche.

OBJECTIVES

The aim of this study was to compare mechanically dissociated SVF (M-SVF) and enzymatically digested SVF (E-SVF) in terms of wound-healing efficacy.

METHODS

Lipoaspirate was partitioned into 2 equal groups and processed by either mechanical or enzymatic isolation methods. After SVF isolation, cell counts and viabilities were determined by flow cytometry and cell proliferation rates were measured by the WST-1 test. A wound-healing scratch assay test, which is commonly used to model in-vitro wound healing, was performed with both cell cocktails. Collagen type 1 (Col1A) gene expression level, which is known for its role in wound healing, was also measured for both groups.

RESULTS

As predicted, E-SVF isolated more cells (mean [standard deviation], 1.74 [3.63] × 106/mL, n = 10, P = 0.015) than M-SVF (0.94 [1.69] × 106/mL, n = 10, P = 0.015), but no significant difference was observed in cell viability. However, M-SVF expressed over 2-fold higher levels of stem cell surface markers and a 10% higher proliferation rate compared with E-SVF. In addition, the migration rate and level of Col1A gene expression of M-SVF were found to be significantly higher than those of E-SVF.

CONCLUSIONS

Although the cell yield of M-SVF was less than that of E-SVF, M-SVF appears to have superior wound-healing properties.

Human platelet lysate as a potential clinical-translatable supplement to support the neurotrophic properties of human adipose-derived stem cells

Background

The autologous nerve graft, despite its donor site morbidity and unpredictable functional recovery, continues to be the gold standard in peripheral nerve repair. Rodent research studies have shown promising results with cell transplantation of human adipose-derived stem cells (hADSC) in a bioengineered conduit, as an alternative strategy for nerve regeneration. To achieve meaningful clinical translation, cell therapy must comply with biosafety. Cell extraction and expansion methods that use animal-derived products, including enzymatic adipose tissue dissociation and the use of fetal bovine serum (FBS) as a culture medium supplement, have the potential for transmission of zoonotic infectious and immunogenicity. Human-platelet-lysate (hPL) serum has been used in recent years in human cell expansion, showing reliability in clinical applications.

Methods

We investigated whether hADSC can be routinely isolated and cultured in a completely xenogeneic-free way (using hPL culture medium supplement and avoiding collagenase digestion) without altering their physiology and stem properties. Outcomes in terms of stem marker expression (CD105, CD90, CD73) and the osteocyte/adipocyte differentiation capacity were compared with classical collagenase digestion and FBS-supplemented hADSC expansion.

Results

We found no significant differences between the two examined extraction and culture protocols in terms of cluster differentiation (CD) marker expression and stem cell plasticity, while hADSC in hPL showed a significantly higher proliferation rate when compared with the usual FBS-added medium. Considering the important key growth factors (particularly brain-derived growth factor (BDNF)) present in hPL, we investigated a possible neurogenic commitment of hADSC when cultured with hPL. Interestingly, hADSC cultured in hPL showed a statistically higher secretion of neurotrophic factors BDNF, glial cell-derived growth factor (GDNF), and nerve-derived growth factor (NFG) than FBS-cultured cells. When cocultured in the presence of primary neurons, hADSC which had been grown under hPL supplementation, showed significantly enhanced neurotrophic properties.

Conclusions

The hPL-supplement medium could improve cell proliferation and neurotropism while maintaining stable cell properties, showing effectiveness in clinical translation and significant potential in peripheral nerve research.

Fat grafts enriched with adipose-derived stem cells

Autologous fat grafts are widely used in soft-tissue augmentation and reconstruction. To reduce the unpredictability of fat grafts and to improve their long-term survival, cell-assisted lipotransfer (CAL) was introduced. In this alternative method, autologous fat is mixed and grafted with stromal vascular fraction cells or adipose-derived stem/stromal cells (ASCs). In regenerative medicine, ASCs exhibit excellent therapeutic potential and are also simple to harvest. Although the efficacy of CAL has been demonstrated in experimental and clinical research, studies on its safety in terms of oncologic risk have reported inconclusive results. In order to establish CAL as a viable stem cell therapeutic approach, it will be necessary to demonstrate its oncologic safety in basic and clinical studies. Doing so could transform the paradigm of clinical strategy and practice for the treatment of a wide variety of diseases.

New Mechanical Fat Separation Technique: Adjustable Regenerative Adipose-tissue Transfer (ARAT) and Mechanical Stromal Cell Transfer (MEST)

Background

Adipose tissue is not only a very important source of filler but also the body's greatest source of regenerative cells.

Objectives

In this study, adipose tissue was cut to the desired dimensions using ultra-sharp blade systems to avoid excessive blunt pressure and applied to various anatomical areas-a procedure known as adjustable regenerative adipose-tissue transfer (ARAT). Mechanical stromal cell transfer (MEST) of regenerative cells from fat tissue was also examined.

Methods

ARAT, MEST, or a combination of these was applied in the facial area of a total of 24 patients who were followed for at least 24 months. The integrity of the fat tissue cut with different diameter blades is shown histopathologically. The number and viability of the stromal cells obtained were evaluated and secretome analyses were performed. Patient and surgeon satisfaction were assessed with a visual analog scale.

Results

With the ARAT technique, the desired size fat grafts were obtained between 4000- and 200-micron diameters and applied at varying depths to different aesthetic units of the face, and a guide was developed. In MEST, stromal cells were obtained from 100 mL of condensed fat using different indication-based protocols with 93% mean viability and cell counts of 28.66 to 88.88 × 10⁶.

Conclusions

There are 2 main complications in fat grafting: visibility in thin skin and a low retention rate. The ARAT technique can be used to prevent these 2 complications. MEST, on the other hand, obtains a high rate of fat and viable stromal cells without applying excessive blunt pressure.

Level of Evidence 4

Towards a Comprehensive Understanding of UA-ADRCs (Uncultured, Autologous, Fresh, Unmodified, Adipose Derived Regenerative Cells, Isolated at Point of Care) in Regenerative Medicine

It has become practically impossible to survey the literature on cells derived from adipose tissue for regenerative medicine. The aim of this paper is to provide a comprehensive and translational understanding of the potential of UA-ADRCs (uncultured, unmodified, fresh, autologous adipose derived regenerative cells isolated at the point of care) and its application in regenerative medicine. We provide profound basic and clinical evidence demonstrating that tissue regeneration with UA-ADRCs is safe and effective. ADRCs are neither 'fat stem cells' nor could they exclusively be isolated from adipose tissue. ADRCs contain the same adult stem cells ubiquitously present in the walls of blood vessels that are able to differentiate into cells of all three germ layers. Of note, the specific isolation procedure used has a significant impact on the number and viability of cells and hence on safety and efficacy of UA-ADRCs. Furthermore, there is no need to specifically isolate and separate stem cells from the initial mixture of progenitor and stem cells found in ADRCs. Most importantly, UA-ADRCs have the physiological capacity to adequately regenerate tissue without need for more than minimally manipulating, stimulating and/or (genetically) reprogramming the cells for a broad range of clinical applications. Tissue regeneration with UA-ADRCs fulfills the criteria of homologous use as defined by the regulatory authorities.

The cell yields and biological characteristics of stromal/stem cells from lipoaspirate with different digestion loading ratio

Effective harvesting procedure for adipose tissue is demanded by the affordable Good Manufacturing Practice-Compliant Production of clinical-grade adipose tissue-derived stem cells (hADSCs). Enzymatic digestion using collagenase is the most reliable method of adipose tissue-derived stem cells (hADSCs) isolation, while the optimized loading volume ratios of digestion to container during the shaking process of adipose tissue and collagenase mixture are still lacking. This study was conducted to determine the optimized loading volume ratio (mixture to container) for enzymatic digestion of Stromal/Stem Cells from lipoaspirate. Lipoaspirates were obtained from twelve women immediately after liposuction. Then tissue from each patient was divided into four groups according to different loading volume ratios in 50 ml centrifugal tube: 0.2 group, 0.4 group, 0.6 group, 0.8 group. Stromal vascular fractions (SVF) were obtained from each group, then total cell counts, viability and viable cell count were performed. hADSCs were harvested at passage (P) 2, whose morphologies, immunophenotypes, proliferation, and tri-differentiation abilities were compared. 0.4 loading volume ratio provided the highest cell yield, favorable viability and viable cell yield. The proliferation and triple differentiation ability of hADSCs obtained by 0.4 group was not inferior to that of other groups. Therefore, 0.4 may be the optimal loading volume ratio for hADSCs isolation from lipoaspirate by enzymatic digestion in current setting.

A 3-step Mechanical Digestion Method to Harvest Adipose-derived Stromal Vascular Fraction

Supplemental Digital Content is available in the text.

Background:

Adipose stromal vascular fraction (SVF) isolation with enzymatic digestion is the gold standard, but is expensive, having practical and legal concerns. The alternative mechanical SVF isolation methods provide lower cell yields as they employ either centrifugation, emulsification, or digestion steps alone. We combined mechanical processing with buffer incubation and centrifugation steps into an isolation method called “mechanical digestion” and compared the cell yields with that of enzymatic digestion.

Methods:

A total of 40-mL lipoaspirate was harvested from 35 women undergoing liposuction and was submitted to conventional enzymatic digestion for SVF isolation or mechanical digestion using a closed unit harnessing 3 ports with blades, followed by buffer incubation and centrifugation. Culture of the SVFs and flow cytometry were performed.

Results:

The SVF cell yield obtained by enzymatic digestion was significantly higher 3.38 × 10⁶/mL (±3.63; n = 35) than that obtained by mechanical digestion 1.34 × 10⁶/mL (±1.69; n = 35), P = 0.015. The average cell viability was 82.86% ± 10.68 after enzymatic digestion versus 85.86% ± 5.74 after mechanical digestion, which was not significant. Mechanical digested SVF expressed 2-fold higher stem cell surface markers compared with enzymatically digested SVF. Mechanical digestion was less time consuming, cost effective, and did not require a specific laboratory environment.

Conclusions:

Mechanically digested SVF was comparable to enzymatically digested SVF in terms of stromal cell composition and viability. With mechanical digestion, we can isolate 30%–50% SVF cells of that isolated with enzymatic digestion. Further studies are warranted to determine the clinical outcomes.

Intraoperative Strategies for Minimal Manipulation of Autologous Adipose Tissue for Cell- and Tissue-Based Therapies: Concise Review

The stromal vascular fraction (SVF) is a heterogeneous population of stem/stromal cells isolated from perivascular and extracellular matrix (ECM) of adipose tissue complex (ATC). Administration of SVF holds a strong therapeutic potential for regenerative and wound healing medicine applications aimed at functional restoration of tissues damaged by injuries or chronic diseases. SVF is commonly divided into cellular stromal vascular fraction (cSVF) and tissue stromal vascular fraction (tSVF). Cellular SVF is obtained from ATC by collagenase digestion, incubation/isolation, and pelletized by centrifugation. Enzymatic disaggregation may alter the relevant biological characteristics of adipose tissue, while providing release of complex, multiattachment of cell-to-cell and cell-to-matrix, effectively eliminating the bioactive ECM and periadventitial attachments. In many countries, the isolation of cellular elements is considered as a "more than minimal" manipulation, and is most often limited to controlled clinical trials and subject to regulatory review. Several alternative, nonenzymatic methods of adipose tissue processing have been developed to obtain via minimal mechanical manipulation an autologous tSVF product intended for delivery, reducing the procedure duration, lowering production costs, decreasing regulatory burden, and shortening the translation into the clinical setting. Ideally, these procedures might allow for the integration of harvesting and processing of adipose tissue for ease of injection, in a single procedure utilizing a nonexpanded cellular product at the point of care, while permitting intraoperative autologous cellular and tissue-based therapies. Here, we review and discuss the options, advantages, and limitations of the major strategies alternative to enzymatic processing currently developed for minimal manipulation of adipose tissue. Stem Cells Translational Medicine 2019;8:1265&1271.

Long-term impact of lipofilling in hybrid breast reconstruction: retrospective analysis of two cohorts

Lipofilling has recently gained popularity as a tool in primary treatment of breast cancer, and its association with two-stage implant breast reconstruction is considered as standard treatment in many centers. However, no data are available about the long-term results of the association of lipofilling in combination with expander-implant reconstruction. A retrospective analysis was conducted on patients treated between January 2010 and December 2014. Two groups were compared. Group 1 had a standard expander-implant two-stage reconstruction. Group 2 underwent hybrid breast reconstruction (HBR). Patient characteristics, hospitalization, outcomes, reoperation details, outpatient visits, and evaluation questionnaires were taken into consideration. Intergroup comparison was performed using Wilcoxon Mann-Whitney U test and Pearson’s chi-square test or Fisher’s exact test for categorical variables. Two hundred fourteen patients were evaluated: 130 patients in group 1 and 84 patients in group 2. Group 2 showed significant benefits over group 1 in terms of capsular contracture rate, breast pain, and displacement/rotation of the implant (p = 0.005). The HBR protocol is associated with lower rate of capsular contracture, less breast pain at long follow-up times, and lower overall rates of revision surgery compared to standard expander-implant reconstruction. A specific cost analysis will help further clarify the advantages of this protocol over a standard procedure.

Level of Evidence: Level III, risk/prognostic, therapeutic study.

Stromal Vascular Fraction and its Role in the Management of Alopecia: A Review

Adipose cells organized in small clusters under the reticular dermis closely interact with hair follicular cells and regulate the hair cycle. Intradermal adipocyte progenitor cells are activated toward the end of the telogen phase to proliferate and differentiate into mature adipocytes. These cells, surrounding the hair follicles, secrete signaling molecules that control the progression of the hair cycle. Diseases associated with defects in adipocyte homeostasis, such as lipodystrophy and focal dermal hypoplasia, lead to alopecia. In this review, we discuss the potential influence of stromal vascular fraction from adipose tissue in the management of alopecia as well as its involvement in preclinical and clinical trials.

Risk factors and complications after body-contouring surgery and the amount of stromal vascular fraction cells found in subcutaneous tissue

Body contouring surgery following massive weight loss is often prone to complications. Subcutaneous adipose tissue is a rich source of stromal vascular fraction (SVF) cells, and moreover it plays an important role in the pathophysiology of obesity, metabolic syndrome, and wound healing. In this retrospective, single-centred appraisal, complications are examined and correlated with individual SVF numbers in abdominal subcutaneous fat tissue. We analysed whether the weight loss method affected complications. Eighty seven massive weight loss patients undergoing body contouring surgery between 2010 and 2017 were included in the study. In total, 57 cases with at least one complication were recorded (65.5%). Maximum lifetime weight was 109.6 kg (range 48-184 kg). Half of the complications (50.8%) were minor complications without the need for surgical revision. The mean number of SVF found in the resected tissue was 714 997.63 cells/g fat tissue. We found no statistical difference in complication rates dependent on cell numbers. Smoking (P = .049) and a high BMI at the time point of surgery (P = .031) led to significantly more complications. Also, a high resection weight (P = .057) showed a tendency for impaired wound healing. However, there was no difference in complication rates following body contouring procedures attributable to the method of weight loss in this study.

Cellular Optimization of Nanofat: Comparison of Two Nanofat Processing Devices in Terms of Cell Count and Viability

Background

Nanofat was introduced by Tonnard and Verpaele in 2013. Their initial observations in intradermal applications showed improvement in the appearance of the skin. Since then, a number of Nanofat devices have been introduced. The cellular content in the processing of Nanofat is not the same in every device, yet the cellular composition is responsible for the biologic action of Nanofat. The authors sought to find a different means to produce a matrix rich Nanofat to optimize the cellular content.

Objectives

The primary objective of this study was to compare cell counts, cultures, and cell viabilities produced by LipocubeNano (Lipocube, Inc., London, UK) in comparison to Tulip’s NanoTransfer (Tulip Medical, San Diego, CA) processing methods.

Methods

Twenty milliliters of fat were harvested from 10 patients in order to test two methods of Nanofat production. Ten milliliters of fat were used to assess each method and, after the final product was obtained, enzymatic digestion for stromal vascular fraction (SVF) isolation was performed. A Muse Flow-cytometer was used to measure cell counts and cell viabilities, cell cultures were performed, and cell images were taken with a florescent microscope.

Results

The LipocubeNano was shown to be superior to Tulip’s NanoTransfer system of progressive downsizing with final filtering, which appeared to trap more fibrous tissue leading to lower amounts of SVF. LipocubeNano resulted in higher cell counts (2.24 × 10⁶/cc), whereas Tulip’s NanoTransfer method resulted in a lower cell count at 1.44 × 10⁶/cc. Cell viability was the same (96.05%) in both groups.

Conclusions

Nanofat from LipocubeNano has a higher regenerative cell count and more SVF cells than the other common mechanical method of Nanofat processing. This new means of mechanical processing preserves more matrix, optimizing the cellular content of the Nanofat, thus having potentially a higher regenerative effect.

Level of Evidence: 5

Stromal vascular fraction technologies and clinical applications

Introduction: The heterogeneous pool of cells found in the stromal vascular fraction of adipose tissue (SVF) and the purified mesenchymal stromal/stem cells (ASCs) isolated from this pool have increasingly been used as therapeutic tools in regenerative medicine.Areas covered: As SVF and ASCs are different, and should be used in different manners according to various clinical and biological indications, we reviewed the current literature, and focused on the clinical use of SVF to appraise the main medical fields for development. Both enzymatic digestion and mechanical disruption have been used to obtain SVF for non-homologous use. The safety and/or benefits of SVF have been examined in 71 clinical studies in various contexts, mainly musculoskeletal conditions, wound healing, urogenital, and cardiovascular and respiratory diseases. The use of SVF as a therapy remains experimental, with few clinical trials.Expert opinion: SVF provides a cellular and molecular microenvironment for regulation of ASC' activities under different clinical conditions. SVF may enhance angiogenesis and neovascularization in wound healing, urogenital and cardiovascular diseases. In joint conditions, therapeutic benefits may rely on paracrine immune-modulatory and anti-inflammatory mechanisms. Novel point of care methods are emerging to refine SVF in ways that meet the regulatory requirements for minimal manipulation.

Isolation of adipose tissue derived regenerative cells from human subcutaneous tissue with or without the use of an enzymatic reagent

Freshly isolated, uncultured, autologous adipose derived regenerative cells (ADRCs) have emerged as a promising tool for regenerative cell therapy. The Transpose RT system (InGeneron, Inc., Houston, TX, USA) is a system for isolating ADRCs from adipose tissue, commercially available in Europe as a CE-marked medical device and under clinical evaluation in the United States. This system makes use of the proprietary, enzymatic Matrase Reagent for isolating cells. The present study addressed the question whether the use of Matrase Reagent influences cell yield, cell viability, live cell yield, biological characteristics, physiological functions or structural properties of the ADRCs in final cell suspension. Identical samples of subcutaneous adipose tissue from 12 subjects undergoing elective lipoplasty were processed either with or without the use of Matrase Reagent. Then, characteristics of the ADRCs in the respective final cell suspensions were evaluated. Compared to non-enzymatic isolation, enzymatic isolation resulted in approximately twelve times higher mean cell yield (i.e., numbers of viable cells/ml lipoaspirate) and approximately 16 times more colony forming units. Despite these differences, cells isolated from lipoaspirate both with and without the use of Matrase Reagent were independently able to differentiate into cells of all three germ layers. This indicates that biological characteristics, physiological functions or structural properties relevant for the intended use were not altered or induced using Matrase Reagent. A comprehensive literature review demonstrated that isolation of ADRCs from lipoaspirate using the Transpose RT system and the Matrase Reagent results in the highest viable cell yield among published data regarding isolation of ADRCs from lipoaspirate.

Intratunical injection of autologous adipose stromal vascular fraction reduces collagen III expression in a rat model of chronic penile fibrosis

Previous studies have shown that the injection of adipose stem cells and stromal vascular fraction(SVF) into the tunica albuginea (TA) during the inflammatory phase in a rat model of Peyronie's disease(PD) prevented the development of TA fibrosis. Our aim was to investigate whether local injection of SVF can reduce established fibrosis in a rat model of chronic phase of PD. Eighteen-male 12-wk-old Sprague-Dawley rats were divided in three equal groups: sham, PD without treatment (PD) and PD treated with SVF(PD-SVF). Sham rats underwent 2 injections of vehicle into the TA one month apart. PD rats underwent TGF-β1 injection and injection of vehicle one month later. PD-SVF rats underwent TGF-β1 injection followed by SVF (1-million cells) one month later. One month after the last treatment, the animals, n = 6 rats per group, underwent measurement of intracorporal and mean arterial pressure during electrostimulation of the cavernous nerve. Following euthanasia, penises were harvested for in-vitro study. Erectile function was not statistically significantly different between groups. PD animals developed subtunical areas of fibrosis and elastosis with upregulation of collagen III protein. These fibrotic changes were reversed after injection of SVF. We provide evidence that local injection of SVF reverses TA fibrosis in a rat model of chronic phase of PD.

Improved guided bone regeneration by combined application of unmodified, fresh autologous adipose derived regenerative cells and plasma rich in growth factors: A first-in-human case report and literature review

BACKGROUND

Novel strategies are needed for improving guided bone regeneration (GBR) in oral surgery prior to implant placement, particularly in maxillary sinus augmentation (GBR-MSA) and in lateral alveolar ridge augmentation (LRA). This study tested the hypothesis that the combination of freshly isolated, unmodified autologous adipose-derived regenerative cells (UA-ADRCs), fraction 2 of plasma rich in growth factors (PRGF-2) and an osteoinductive scaffold (OIS) (UA-ADRC/PRGF-2/OIS) is superior to the combination of PRGF-2 and the same OIS alone (PRGF-2/OIS) in GBR-MSA/LRA.

CASE SUMMARY

A 79-year-old patient was treated with a bilateral external sinus lift procedure as well as a bilateral lateral alveolar ridge augmentation. GBR-MSA/LRA was performed with UA-ADRC/PRGF-2/OIS on the right side, and with PRGF-2/OIS on the left side. Biopsies were collected at 6 wk and 34 wk after GBR-MSA/LRA. At the latter time point implants were placed. Radiographs (32 mo follow-up time) demonstrated excellent bone healing. No radiological or histological signs of inflammation were observed. Detailed histologic, histomorphometric, and immunohistochemical analysis of the biopsies evidenced that UA-ADRC/PRGF-2/OIS resulted in better and faster bone regeneration than PRGF-2/OIS.

CONCLUSION

GBR-MSA with UA-ADRCs, PRGF-2, and an OIS shows effectiveness without adverse effects.

Mesothelial Stem Cells and Stromal Vascular Fraction for Skin Rejuvenation

The use of stem cells in regenerative medicine and specifically facial rejuvenation is thought provoking and controversial. Today there is increased emphasis on tissue engineering and regenerative medicine, which translates into a need for a reliable source of stem cells in addition to biomaterial scaffolds and cytokine growth factors. Adipose tissue is currently recognized as an accessible and abundant source for adult stem cells. Cellular therapies and tissue engineering are still in their infancy, and additional basic science and preclinical studies are needed before cosmetic and reconstructive surgical applications can be routinely undertaken and satisfactory levels of patient safety achieved.