Effect of age and body mass index on the yield of stromal vascular fraction

Understanding and controlling the variables for stromal vascular fraction therapy

In regenerative medicine, the isolation of mesenchymal stromal cells (MSCs) from the adipose tissue’s stromal vascular fraction (SVF) is a critical area of study. Our review meticulously examines the isolation process of MSCs, starting with the extraction of adipose tissue. The choice of liposuction technique, anatomical site, and immediate processing are essential to maintain cell functionality. We delve into the intricacies of enzymatic digestion, emphasizing the fine-tuning of enzyme concentrations to maximize cell yield while preventing harm. The review then outlines the filtration and centrifugation techniques necessary for isolating a purified SVF, alongside cell viability assessments like flow cytometry, which are vital for confirming the efficacy of the isolated MSCs. We discuss the advantages and drawbacks of using autologous vs allogeneic SVF sources, touching upon immunocompatibility and logistical considerations, as well as the variability inherent in donor-derived cells. Anesthesia choices, the selection between hypodermic needles vs liposuction cannulas, and the role of adipose tissue lysers in achieving cellular dissociation are evaluated for their impact on SVF isolation. Centrifugation protocols are also analyzed for their part in ensuring the integrity of the SVF. The necessity for standardized MSC isolation protocols is highlighted, promoting reproducibility and successful clinical application. We encourage ongoing research to deepen the understanding of MSC biology and therapeutic action, aiming to further the field of regenerative medicine. The review concludes with a call for rigorous research, interdisciplinary collaboration, and strict adherence to ethical and regulatory standards to safeguard patient safety and optimize treatment outcomes with MSCs.

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.

Medium- and Long-Term Outcomes of Autologous Fat Grafting to Hands and Feet for Patients With Raynaud Phenomenon

BACKGROUND

Autologous fat grafting (AFG) has emerged as a promising treatment option for Raynaud phenomenon. However, existing studies are limited by short follow-up, and there is little evidence regarding predictive factors for successful outcomes.

METHODS

A retrospective chart review and standardized phone interviews were performed for all patients (n = 17, 65% response rate) treated with AFG to the hands or feet at our institution for primary or secondary Raynaud from 2010 to 2021. Each occurrence of AFG was defined as a separate surgery (n = 23), with an average follow-up of 3.7 years.

RESULTS

At follow-up, patients reported a 31% reduction in cold attack frequency, a 45% reduction in the intensity of individual attacks, a 29% reduction in the duration of attacks, and a 40% improvement in overall Raynaud Condition Score (P < 0.01). Although initial AFG to an extremity significantly improved symptoms, subsequent attempts were not shown to statistically improve outcomes. Digital ulcers were present in 65% of cases, and AFG resulted in ulcer healing in 87% of those cases. Median duration of maximum symptom relief was 1 year postoperatively, with 74% of patients reporting diminishing symptom relief by 4 years postoperatively. Those with a BMI ≥25, with primary Raynaud phenomenon or without preoperative ulcers experienced significantly longer symptom relief (P < 0.05). Average patient satisfaction was 7.7 of 10, and 91% would recommend the procedure to others.

CONCLUSIONS

Autologous fat grafting is an effective, albeit sometimes temporary, treatment for Raynaud and digital ulcers. Certain patients may be more likely to experience lasting symptom relief beyond 1 year.

Cartilage lesion size and number of stromal vascular fraction (SVF) cells strongly influenced the SVF implantation outcomes in patients with knee osteoarthritis

PURPOSE

This study evaluated outcomes in patients with knee osteoarthritis following stromal vascular fraction implantation and assessed the associated prognostic factors.

METHODS

We retrospectively evaluated 43 patients who underwent follow-up magnetic resonance imaging 12 months after stromal vascular fraction implantation for knee osteoarthritis. Pain was assessed using the visual analogue scale and measured at baseline and 1-, 3-, 6-, and 12-month follow-up appointments. In addition, cartilage repair was evaluated based on the Magnetic Resonance Observation of Cartilage Repair Tissue scoring system using the magnetic resonance imaging from the 12-month follow-up. Finally, we evaluated the effects of various factors on outcomes following stromal vascular fraction implantation.

RESULTS

Compared to the baseline value, the mean visual analogue scale score significantly and progressively decreased until 12 months post-treatment (P < 0.05 for all, except n.s. between the 1 and 3-month follow-ups). The mean Magnetic Resonance Observation of Cartilage Repair Tissue score was 70.5 ± 11.1. Furthermore, the mean visual analogue scale and Magnetic Resonance Observation of Cartilage Repair Tissue scores significantly correlated 12 months postoperatively (P = 0.002). Additionally, the cartilage lesion size and the number of stromal vascular fraction cells significantly correlated with the 12-month visual analogue scale scores and the Magnetic Resonance Observation of Cartilage Repair Tissue score. Multivariate analyses determined that the cartilage lesion size and the number of stromal vascular fraction cells had a high prognostic significance for unsatisfactory outcomes.

CONCLUSION

Stromal vascular fraction implantation improved pain and cartilage regeneration for patients with knee osteoarthritis. The cartilage lesion size and the number of stromal vascular fraction cells significantly influenced the postoperative outcomes. Thus, these findings may serve as a basis for preoperative surgical decisions.

LEVEL OF EVIDENCE

IV.

Adipose Tissue-Derived Components: From Cells to Tissue Glue to Treat Dermal Damage

In recent decades, adipose tissue transplantation has become an essential treatment modality for tissue (volume) restoration and regeneration. The regenerative application of adipose tissue has only recently proven its usefulness; for example, the method is useful in reducing dermal scarring and accelerating skin-wound healing. The therapeutic effect is ascribed to the tissue stromal vascular fraction (tSVF) in adipose tissue. This consists of stromal cells, the trophic factors they secrete and the extracellular matrix (ECM), which have immune-modulating, pro-angiogenic and anti-fibrotic properties. This concise review focused on dermal regeneration using the following adipose-tissue components: adipose-tissue-derived stromal cells (ASCs), their secreted trophic factors (ASCs secretome), and the ECM. The opportunities of using a therapeutically functional scaffold, composed of a decellularized ECM hydrogel loaded with trophic factors of ASCs, to enhance wound healing are explored as well. An ECM-based hydrogel loaded with trophic factors combines all regenerative components of adipose tissue, while averting the possible disadvantages of the therapeutic use of adipose tissue, e.g., the necessity of liposuction procedures with a (small) risk of complications, the impossibility of interpatient use, and the limited storage options.

Stromal Vascular Fraction Obtained From Subcutaneous Adipose Tissue: Ex-Obese and Older Population as Main Clinical Targets

INTRODUCTION

Human adipose tissue contains a heterogeneous and synergistic mixture of cells called stromal vascular fraction (SVF) with highly proliferative and angiogenic properties, conferring promising applicability in the field of regenerative medicine. This study aims to investigate if age, body mass index (BMI), history of obesity and massive weight loss, and harvest site are related to SVF cell marker expression.

METHODS

A total of 26 samples of subcutaneous adipose tissue were harvested from patients admitted to the Plastic and Reconstructive department in University Hospital Center of São João, Porto, Portugal, for body contouring surgery. The percentage of cells expressing CD31, CD34, CD45, CD73, CD90, and CD105 was assessed and compared with patient's age, BMI, history of obesity and massive weight loss (ex-obese group), and harvest site.

RESULTS

In the ex-obese group, a significantly higher number of cells expressing CD90 (P = 0.002) was found. BMI, harvest site, and age appear to have no association with SVF subpopulations.

CONCLUSIONS

This study suggests that ex-obese patients have a higher percentage of SVF cells expressing CD90, which correlates with higher proliferative and angiogenic rates. The effect of former obesity and massive weight loss on the expression of CD90 is a new and relevant finding because it makes this population a suitable candidate for reconstructive and aesthetic surgery and other fields of regenerative medicine. The use of SVF appears also promising in older patients because no negative correlation between increasing age and different cell markers expression was found.

Adipose-Derived Stem Cells, Obesity, and Inflammation: A Systematic Review and Implications for Osteoarthritis Treatment

ABSTRACT

Adipose is a known source of mesenchymal stem cells that can be used to treat musculoskeletal disorders, such as osteoarthritis. Because obesity often coexists with osteoarthritis, excess adiposity may be a useful source of mesenchymal stem cells. However, obesity is associated with systemic inflammation, which may influence the quality of adipose-derived stem cells. We performed a systematic review of the literature examining adipose-derived stem cell behavior, cytokine, and growth factor profiles from obese and nonobese patients. Two independent reviewers applied the inclusion/exclusion criteria and independently extracted data including mesenchymal stem cell count/viability/behavior, growth factor, and/or cytokine expression. Twenty-two articles met criteria for inclusion. Samples from obese patients had increased mesenchymal stem cell content (n = 6), but decreased proliferative ability (n = 3), and increased expression of interleukin 1 (n = 3), interleukin 6 (n = 3), and tumor necrosis factor α (n = 6). There was also greater macrophage content (n = 4). Weight loss normalized cellular function. In vitro behavior and quality of adipose-derived stem cell are significantly different between obese and nonobese patients. Samples from obese patients had greater adipose-derived stem cell content, lower proliferative ability, increased senescence, and increased proinflammatory cytokine expression. Differences in cellular function should be considered when using adipose to treat musculoskeletal pathology in obese and nonobese patients.

Factors affecting cell viability and the yield of adipose-derived stromal vascular fraction

The stromal vascular fraction (SVF) is isolated from adipose tissue and has tremendous regenerative potential for proliferation and differentiation. This study aimed to investigate the factors affecting the cell yield and viability of the SVF to improve the outcomes of its clinical applications and enhance its clinical usage. We performed a retrospective analysis with 121 patients who underwent liposuction to harvest adipose-derived SVF. We recorded patient demographic and clinical characteristics, including age, sex, body mass index (BMI), blood type, medical comorbidities, and smoking and alcohol consumption. As for operative variables, we noted the amount of lipoaspirate and the donor areas, including the lower and entire abdomen. The viability and the cell count of SVF were documented. Sex was a statistically significant factor for viability rate (p < 0.015) and cell count (p < 0.009). Men had higher viability, while women had higher cell counts. We found a statistically significant difference in the presence of hypertension (p = 0.024) and alcohol consumption (p = 0.024). There was a statistically significant relationship between cell count and age (p < 0.001), BMI (p = 0.006), and amount of lipoaspirate (p < 0.001). Sex had significant associations with cell count and viability, while age, BMI, and lipoaspirate amount were significantly associated with cell count. Hypertension and alcohol consumption significantly affected cell count, which is the first such report of this association. Surgeons could apply this knowledge to patient selection for optimal treatment outcomes. Additionally, understanding these factors can help manage patient expectations.

Research update of adipose tissue-based therapies in regenerative dermatology

Mesenchymal stromal/stem cells (MSCs) have a spontaneous propensity to support tissue homeostasis and regeneration. Among the several sources of MSCs, adipose-derived tissue stem cells (ADSCs) have received major interest due to the higher mesenchymal stem cells concentration, ease, and safety of access. However, since a significant part of the natural capacity of ADSCs to repair damaged tissue is ascribable to their secretory activity that combines mitogenic factors, cytokines, chemokines, lipids, and extracellular matrix components, several studies focused on cell-free strategies. Furthermore, adipose cell-free derivatives are becoming more attractive especially for non-volumizing purposes, such as most dermatological conditions. However, when keratinocytes, fibroblasts, melanocytes, adipocytes, and hair follicle cells might not be locally sourced, graft of materials containing concentrated ADSCs is preferred. The usage of extracellular elements of adipose tissue aims to promote a self-autonomous regenerative microenvironment in the receiving area restoring physiological homeostasis. Hence, ADSCs or their paracrine activity are currently being studied in several dermatological settings including wound healing, skin fibrosis, burn, and aging.The present work analyzing both preclinical and clinical experiences gives an overview of the efficacy of adipose tissue-derivatives like autologous fat, the stromal vascular fraction (SVF), purified ADSCs, secretome and extracellular matrix graft in the field of regenerative medicine for the skin.

Smoking and Physical Activity Significantly Influence Stromal Vascular Fraction Cell Yield and Viability

BACKGROUND

Subcutaneous tissue is an abundant source of adipose-derived regenerative cells. It is readily available and easy to extract by means of liposuction, making it one of the most popular sources for tissue engineering and regenerative medical applications.

METHODS

The stromal vascular fraction (SVF) cell yield and viability of the lipoaspirate obtained from 43 patients undergoing elective liposuction were examined in correlation with their age, gender, body mass index, smoking status, and physical activity. The lipoaspirate was processed with the Celution^® 800/CRS system to isolate the SVF and a few drops of the obtained pellet were used for cell counting with NecleoCounter^® NC-100^TM.

RESULTS

Twenty-eight (65.1%) were men and 15 (34.9%) were women with an average age of 40.7 ± 10.4 years (women) and 38.9 ± 11.8 years (men). Viable SVF cells/g fat was significantly correlated with smoking level (negative correlation, ρ=  - 0.312, P < 0.05) and with marginal significance with female gender. Cell viability showed a significant negative correlation with physical activity level (ρ =   - 0.432, P < 0.01); borderline significance for correlation of this parameter with smoking level should not be neglected. Other parameters did not influence the cell yield nor the viability of the stromal vascular fraction.

CONCLUSION

Many factors may influence SVF cell yield and viability. Our findings indicate that age and smoking significantly influenced SVF cell yield, age positively while smoking negatively. Increased physical activity had a negative correlation with SVF cell viability.

LEVEL OF EVIDENCE N/A

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

[Current review of factors in the stem cell donor that influence the regenerative potential of adipose tissue-derived stem cells]

BACKGROUND

Regenerative therapies like cell-assisted lipotransfer or preclinical experimental studies use adipose tissue-derived stem cells (ASCs) as the main therapeutic agent. But there are also factors depending on the clinical donor that influence the cell yield and regenerative potential of human ASCs and stromal vascular fraction (SVF). Therefore, the aim of this review was to identify and evaluate these factors according to current literature.

METHODS

For this purpose, a systematic literature review was performed with focus on factors affecting the regenerative potential of ASCs and SVF using the National Library of Medicine.

RESULTS

Currently, there is an abundance of studies regarding clinical donor factors influencing ASCs properties. But there is some contradiction and need for further investigation. Nevertheless, we identified several recurrent factors: age, sex, weight, diabetes, lipoedema, use of antidepressants, anti-hormonal therapy and chemotherapy.

CONCLUSION

We recommend characterisation of the ASC donor cohort in all publications, regardless of whether they are experimental studies or clinical trials. By these means, donor factors that influence experimental or clinical findings can be made transparent and results are more comparable. Moreover, this knowledge can be used for study design to form a homogenous donor cohort by precise clinical history and physical examination.

The Impact of Lidocaine on Adipose-Derived Stem Cells in Human Adipose Tissue Harvested by Liposuction and Used for Lipotransfer

The local anesthetic lidocaine, which has been used extensively during liposuction, has been reported to have cytotoxic effects and therefore would be unsuitable for use in autologous lipotransfer. We evaluated the effect of lidocaine on the distribution, number, and viability of adipose-derived stem cells (ASCs), preadipocytes, mature adipocytes, and leukocytes in the fatty and fluid portion of the lipoaspirate using antibody staining and flow cytometry analyses. Adipose tissue was harvested from 11 female patients who underwent liposuction. Abdominal subcutaneous fat tissue was infiltrated with tumescent local anesthesia, containing lidocaine on the left and lacking lidocaine on the right side of the abdomen, and harvested subsequently. Lidocaine had no influence on the relative distribution, cell number, or viability of ASCs, preadipocytes, mature adipocytes, or leukocytes in the stromal-vascular fraction. Assessing the fatty and fluid portions of the lipoaspirate, the fatty portions contained significantly more ASCs (p < 0.05), stem cells expressing the preadipocyte marker Pref-1 (p < 0.01 w/lidocaine, p < 0.05 w/o lidocaine), and mature adipocytes (p < 0.05 w/lidocaine, p < 0.01 w/o lidocaine) than the fluid portions. Only the fatty portion should be used for transplantation. This study found no evidence that would contraindicate the use of lidocaine in lipotransfer. Limitations of the study include the small sample size and the inclusion of only female patients.