The role of extracellular matrix hydrogels and adipose-derived stromal cells in soft tissue vascularization - A systematic review.

Decellularized extracellular matrix (dECM) hydrogels loaded with adipose-derived stromal cells (ASC) or their conditioned medium (ASC CM) present a promising and versatile treatment approach for tissue vascularization and regeneration. These hydrogels are easy to produce, store, personalize, manipulate, and deliver to the target tissue. This literature review aimed to investigate the applications of dECM hydrogels with ASC or ASC CM for in vivo tissue vascularization. Fourteen experimental studies have been reviewed using vessel density as the primary outcome parameter for in vivo vascularization. The studies consistently reported an increased efficacy in augmenting angiogenesis by the ASC or ASC CM-loaded hydrogels compared to untreated controls. However, this systematic review shows the need to standardize procedures and characterization, particularly of the final administered product(s). The findings from these experimental studies highlight the potential of dECM hydrogel with ASC or ASC CM in novel tissue regeneration and regenerative medicine applications.

Efficacy of stromal vascular fraction in the treatment of scars: A systematic review and meta-analysis.

OBJECTIVE: Our aim was to assess the effectiveness of stromal vascular fraction (SVF) in treating scars using the latest meta-analysis. METHODS: We used PubMed, Embase, Cochrane, and Web of Science to search the studies used to evaluate the efficacy of SVF in scar treatment. At least one of the following outcome measures were reported: vascularity, pigmentation, thickness, relief, pliability, surface area, pain, itching and color. RESULTS: A total of four eligible articles comprising 145 patients (64 SVF patients and 81 non-SVF patients) were included. The findings of this meta-analysis indicated that SVF had significant therapeutic effects in terms of vascularity (SMD/MD, 95% CI: -1.12, -0.02; p = 0.04), itching (SMD/MD, 95% CI: -0.61, -0.13; p = 0.002), POSAS (SMD/MD, 95% CI: -5.93, -1.47; p = 0.001), and thickness (SMD/MD, 95% CI: -1.04, -0.35; p < 0.001). In terms of OSAS (SMD/MD, 95% CI: -9.14, 0.59; p = 0.09), pigmentation (SMD/MD, 95% CI: -1.02, 0.06; p = 0.08), relief (SMD/MD, 95% CI: -1.14, 0.16; p = 0.14), surface area (SMD/MD, 95% CI: -0.91, 0.26; p = 0.27), PSAS (SMD/MD, 95% CI: -7.20, 0.49; p = 0.09), pain (SMD/MD, 95% CI: -0.87, 0.07; p = 0.10), pliability (SMD/MD, 95% CI: -0.57, 0.01; p = 0.06), and color (SMD/MD, 95% CI: -1.78, 0.48; p = 0.26), there were no significant statistical differences. CONCLUSION: In view of the heterogeneity and potential selective bias, further large-scale, prospective, and multicenter clinical trials are needed to confirm the efficacy and reliability of SVF in the treatment of scars.

The effects of testicular stromal stem cells on surgically injured testicular tissue in rats.

This study investigated the effects of transplanted testicular stromal stem cells (tSSCs) on surgically damaged testis tissue. Ten-week-old male Wistar albino rats were divided into three groups: control (n = 6), damage (DG) (n = 6) and testicular stromal stem cell (TSSC) (n = 6) groups. Surgically induced damage was inflicted on the left testes of both the DG and TSSC groups, with no intervention on the right testes. In the TSSC group, damaged testes were treated with transplanted tSSCs, followed by orchiectomy after 15 days. Testes tissues were stained with haematoxylin-eosin (H&E), and recovery rates of functional structures were assessed by modified Johnsen scoring. The effects of tSSCs on testicular tissue were demonstrated by immunohistochemistry using BAX, BCL-2 and caspase 3. Serum testosterone levels were analysed using the enzyme-linked immunosorbent assay (ELISA) method. Surgical damage caused germ cell degeneration in some seminiferous tubules and a decrease in interstitial areas. With tSSC treatment, improvements in testicular architecture were identified through spermatogenesis in the seminiferous tubules and normal histological structures in the interstitial areas. Correspondingly, in the modified Johnsen score, the DG group showed a significant difference compared to the other groups (p = 0.001). High expressions of BAX, BCL-2 and caspase-3 in the DG group revealed prominent features of apoptosis. With the injection of tSSCs, these expressions significantly normalized according to H score analysis (all p = 0.004). Although serum testosterone levels in the tSSC group were higher compared to the control and DG groups, this difference was not statistically significant (p = 0.119). This study suggests transplanting tSSCs could accelerate tissue healing after testicular sperm extraction (TESE) surgery for azoospermia patients, potentially paving the way for a new and important clinical treatment.

Restoration of functional endometrium in an intrauterine adhesion rat model with endometrial stromal cells transplantation.

BACKGROUND: Intrauterine adhesion (IUA) as a prevalent gynecological disease is developed from infection or trauma. However, therapeutic strategies to repair damaged endometrium are relatively limited. Emerging studies have shed light on the crucial role of endometrial stromal cells (EnSCs) in the process of uterine endometrial regeneration. EnSCs isolated from the uterine endometrium have similar characteristics to mesenchymal stem cells (MSCs). However, it is still unknown whether EnSCs could be used as donor cells to treat IUA. The aim of this study was to evaluate the potential efficacy of EnSCs in treating rat IUA. METHODS: Human EnSCs were isolated from the endometrial tissue of healthy female donors and subjected to extensive expansion and culture in vitro. Immunofluorescence, flow cytometry, cell proliferation assay, trilineage differentiation experiment, and decidualization assay were used to characterize the biological properties of EnSCs. We evaluated the immunoregulatory potential of EnSCs by analyzing their secreted cytokines and conducting bulk RNA sequencing after IFN-γ treatment. After EnSCs were transplanted into the uterine muscle layer in IUA rats, their therapeutic effects and underlying mechanisms were analyzed using histological analysis, Q-PCR, fertility and pregnancy outcome assay, and transcriptome analysis. RESULTS: We successfully isolated EnSCs from the endometrium of human donors and largely expanded in vitro. EnSCs exhibited characteristics of mesenchymal stem cells and retained responsiveness to sex hormones. Following IFN-γ stimulation, EnSCs upregulated the anti-inflammatory cytokines and activated immunosuppressive molecules. Xenogeneic transplantation of EnSCs successfully repaired injured endometrium and significantly restored the pregnancy rate in IUA rats. Mechanistically, the therapeutic effects of EnSCs on IUA endometrium functioned through anti-inflammation, anti-fibrosis and the secretion of regeneration factor. CONCLUSIONS: Due to their large expansion ability, immunoregulatory properties, and great potential in treating IUA, EnSCs, as a valuable source of donor cells, could offer a potential treatment avenue for injury-induced IUA.

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.

Spatial Growth Factor Delivery for 3D Bioprinting of Vascularized Bone with Adipose-Derived Stem/Stromal Cells as a Single Cell Source.

Encapsulating multiple growth factors within a scaffold enhances the regenerative capacity of engineered bone grafts through their localization and controls the spatiotemporal release profile. In this study, we bioprinted hybrid bone grafts with an inherent built-in controlled growth factor delivery system, which would contribute to vascularized bone formation using a single stem cell source, human adipose-derived stem/stromal cells (ASCs) in vitro. The strategy was to provide precise control over the ASC-derived osteogenesis and angiogenesis at certain regions of the graft through the activity of spatially positioned microencapsulated BMP-2 and VEGF within the osteogenic and angiogenic bioink during bioprinting. The 3D-bioprinted vascularized bone grafts were cultured in a perfusion bioreactor. Results proved localized expression of osteopontin and CD31 by the ASCs, which was made possible through the localized delivery activity of the built-in delivery system. In conclusion, this approach provided a methodology for generating off-the-shelf constructs for vascularized bone regeneration and has the potential to enable single-step, in situ bioprinting procedures for creating vascularized bone implants when applied to bone defects.

A Novel Method to Repair Thin Endometrium and Restore Fertility Based on Menstruation-Derived Stem Cell.

Thin endometrium (TE), which mainly occurs as a result of severe damage to the endometrial basalis, is one of the prominent etiologies of menstrual abnormalities, infertility, and recurrent miscarriage in women. Previous studies have demonstrated that mesenchymal stem cells (MSCs) are considered ideal cells with multipotency for regenerative medicine and exhibit therapeutic effects on TE through their cellular secretions. However, there is limited research on strategies to enhance MSC secretion to improve their therapeutic efficacy. Herein, we isolated menstrual blood-derived mesenchymal stem cells (MenSCs) from menstruation and transformed them into decidualized stromal cells (DSCs), which are specialized cells with enhanced secretory functions. To assess the therapeutic potential of DSCs compared to MenSCs, we conducted a series of experiments in cells and animals. The results demonstrated that DSCs exhibited changes in morphology compared to MenSCs, with a decrease in cell proliferation but a significant improvement in secretion function. Furthermore, DSCs facilitated the restoration of endometrial thickness and increased the number of glands and blood vessel formation. Most importantly, the pregnancy rates in rats were effectively restored, bringing them closer to normal levels. These findings greatly contribute to our understanding of stem cell therapy for TE and strongly suggest that DSCs could hold significant promise as a potential treatment option for TE.

Enhanced Effect of Secondary Administration of Adipose-Derived Stromal Cells Concurrent with Fat Grafting.

BACKGROUND: Cell-assisted lipotransfer, a fat graft mixed with adipose-derived stromal cells, is known to enhance fat graft retention. Previously, the authors showed that intravenous injection of adipose-derived stromal cells can improve the survival of grafted fat. In the present study, the authors investigated the effects of a secondary intravenous injection of adipose-derived stromal cells on fat grafting. METHODS: Wild-type C57BL/6J (B6) mice were used as donors for grafted fat and as recipients. Adipose-derived stromal cells were harvested from green fluorescent protein and DsRed B6 mice. The recipient mice were divided into three groups: SI ( n = 10), RI1 ( n = 10), and RI2 ( n = 11). All groups received intravenous injections of green fluorescent protein adipose-derived stromal cells immediately after fat grafting. The RI1 and RI2 groups received repeated intravenous injections of DsRed adipose-derived stromal cells at 1 and 2 weeks, respectively, after fat grafting. The grafted fat volume was measured using micro-computed tomography. RESULTS: Secondarily injected DsRed adipose-derived stromal cells were recruited to the grafted fat and resulted in a higher retention of graft volume and vascular density ( P < 0.05). The stromal-derived factor-1 and C-X-C chemokine receptor type 4 genes related to stem cell homing were highly expressed in the grafted fat and adipose-derived stromal cells ( P < 0.05). The RI2 group showed a higher graft volume and vascular density than the SI and RI1 groups ( P < 0.05). CONCLUSIONS: A secondary intravenous injection of adipose-derived stromal cells at a 2-week interval enhances the effect of adipose-derived stromal cell enrichment in fat grafting. These findings refine clinical protocols and enhance the therapeutic value of cell-assisted lipotransfer. CLINICAL RELEVANCE STATEMENT: In a modified animal model of cell-assisted lipotransfer, the authors demonstrated that secondary intravenous administration of adipose-derived stromal cells improved retention of grafted fat.

Improving Facial Fat Graft Survival Using Stromal Vascular Fraction-Enriched Lipotransfer: A Multicenter Randomized Controlled Study.

BACKGROUND: Although previous clinical studies have reported that cell-assisted lipotransfer increases the fat survival rate in facial fat transplants, most were case studies without quantitative evaluation. A multicenter randomized controlled study was performed to evaluate the safety and efficacy of the stromal vascular fraction (SVF) in facial fat grafts. METHODS: Twenty-three participants were enrolled for autologous fat transfer in the face, and assigned randomly to the experimental ( n = 11) or control ( n = 12) group. Fat survival was assessed using magnetic resonance imaging at 6 and 24 weeks postoperatively. Subjective evaluations were performed by the patients and surgeons. To address safety concerns, results of an SVF culture and the postoperative complications were recorded. RESULTS: The overall fat survival rate was significantly higher in the experimental group than in the control group (6 weeks, 74.5% ± 9.99% versus 66.55% ± 13.77%, P < 0.025; 24 weeks, 71.27% ± 10.43% versus 61.98% ± 13.46%, P < 0.012). Specifically, graft survival in the forehead was 12.82% higher in the experimental group when compared with that in the control group at 6 weeks ( P < 0.023). Furthermore, graft survival in the forehead ( P < 0.021) and cheeks ( P < 0.035) was superior in the experimental group at 24 weeks. At 24 weeks, the aesthetic scores given by the surgeons were higher in the experimental group than in the control group ( P < 0.03); however, no significant intergroup differences were noted in the patient-evaluated scores. Neither bacterial growth from SVF cultures nor postoperative complications were noted. CONCLUSION: SVF enrichment for autologous fat grafting can be a safe and effective technique for increasing the fat retention rate. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

A Study on Breast Augmentation Using Fat Grafting With Stromal Vascular Fraction.

BACKGROUND: Stromal vascular fraction (SVF) and fat grafting are emerging alternatives to implants for breast augmentation. However, the lack of controlled clinical data has led to conflicting results regarding the effectiveness of surgical treatments. This study aimed to identify the key factors affecting the outcomes of fat grafting with SVF and to recognize novel methods to improve the retention rate. PATIENTS AND METHODS: In total, 384 women underwent breast augmentation using fat grafting with SVF. The patients were preoperatively and postoperatively managed and recalled for follow-up at 3, 6, and 18 months. RESULTS: The average volume of the injection in the left breast was 162.35 mL (range, 50-260 mL). The postoperative retention rates were 78.65% in 384 patients at 3 months, 77.17% in 273 patients at 6 months, and 77.48% in 102 patients at 18 months. The retention rates were compared based on the number of SVF cells; patients with more than 60 million cells had a retention rate of 70.77%, and those with less than 60 million cells had a retention rate of 85.60% at 18 months. The retention rates at the 18-month follow-up were 65.62% and 85.09% in stiff and soft breasts, respectively. A higher number of cells in the SVF was associated with a greater retention volume, and the retention volume was greater in patients with soft breasts.Given the higher use of the right arm, after 18 months of the surgery, the retention rate of the right breast (60.35%) was lower than that of the left breast (77.48%) ( P < 0.05; t = -13.199). CONCLUSIONS: Limiting arm movement, increasing the number of cells in the SVF, and improving the skin tension might enhance the retention rate in patients undergoing breast augmentation.

Fat Grafting With Expanded Adipose-Derived Stromal Cells for Breast Augmentation: A Randomized Controlled Trial.

BACKGROUND: The main challenge with fat grafting is loss of some of the graft to postsurgery resorption. Previous studies suggest that adipose-derived stromal cells (ASCs) can improve the volume retention of fat grafts but there is a lack of randomized trials to support the use of ASCs in clinical practice. OBJECTIVES: This trial aimed to investigate whether ASCs improve fat graft volume retention in patients undergoing breast augmentation with lipofilling. METHODS: This was a double-blind, randomized controlled trial of breast augmentation with ASC-enriched fat grafting. Healthy women aged 30 to 45 years were enrolled. First, the participants underwent liposuction to obtain fat for culture expansion of ASCs. Then, the participants were randomly assigned to undergo a 300- to 350-mL breast augmentation with ASC-enriched fat grafting (10 × 106 ASCs/mL fat graft) to 1 of their breasts and placebo-enriched fat grafting of identical volume to the contralateral breast. The primary outcome was fat graft volume retention after a 1-year follow-up measured with MRI. The trial is registered at www.clinicaltrialsregister.eu (EudraCT-2014-000510-59). RESULTS: Ten participants were included in the trial; all completed the treatment and follow-up. No serious adverse events occurred. Fat graft volume retention after 1 year was 54.0% (95% CI, 30.4%-77.6%) in the breasts treated with ASC-enriched fat grafting (n = 10) and 55.9% (95% CI, 28.9%-82.9%) in the contralateral breasts treated with placebo-enriched fat grafting (n = 10) (P = 0.566). CONCLUSIONS: The findings of this trial do not support that ASC-enriched fat grafting is superior to standard fat grafting for breast augmentation.

Supplementation of Facial Fat Grafting to Increase Volume Retention: A Systematic Review.

BACKGROUND: For decades, facial fat grafting has been used in clinical practice for volume restoration. The main challenge of this technique is variable volume retention. The addition of supplements to augment fat grafts and increase volume retention has been reported in recent years. OBJECTIVES: The aim of this systematic review was to investigate which supplements increase volume retention in facial fat grafting as assessed by volumetric outcomes and patient satisfaction. METHODS: Embase, Medline, Ovid, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and Google Scholar were searched up to November 30, 2020. Only studies assessing volume after facial fat grafting with supplementation in human subjects were included. Outcomes of interest were volume or patient satisfaction. The quality of the studies was assessed with the Effective Public Health Practice Project tool. RESULTS: After duplicates were removed 3724 studies were screened by title and abstract. After reading 95 full-text articles, 27 studies were eligible and included for comparison. Supplementation comprised of platelet-rich plasma, platelet-rich fibrin, adipose tissue-derived stromal cells or bone marrow-derived stromal cells, cellular or tissue stromal vascular fraction, or nanofat. In 13 out of 22 studies the supplemented group showed improved volumetric retention and 5 out of 16 studies showed greater satisfaction. The scientific quality of the studies was rated as weak for 20 of 27 studies, moderate for 6 of 27 studies, and strong for 1 study. CONCLUSIONS: It remains unclear if additives contribute to facial fat graft retention and there is a need to standardize methodology.

Effects of adipose-derived stromal cells and endothelial progenitor cells on adipose transplant survival and angiogenesis.

BACKGROUND: A paracrine mechanism is thought to mediate the proangiogenic capacity of adipose-derived stromal/stem cells (ASCs). However, the precise mechanism by which ASCs promote the formation of blood vessels by endothelial progenitor cells (EPCs) is unclear. METHODS: The EPCs-ASCs cocultures prepared in different ratios were subjected to tube formations assay to verify whether ASCs could directly participate in the tube genesis. The supernatant from cultured ASCs was used to stimulate EPCs to evaluate the effects on the angiogenic property of EPCs, as well as capacity for migration and invasion. A coculture model with transwell chamber were used to explore the regulation of angiogenesis markers expression in EPCs by ASCs. We then mixed ASCs with EPCs and transplanted them with adipose tissue into nude mice to evaluate the effects on angiogenesis in adipose tissue grafts. RESULTS: In the EPCs-ASCs cocultures, the tube formation was significantly decreased as the relative abundance of ASCs increased, while the ASCs was found to migrate and integrated into the agglomerates formed by EPCs. The supernatant from ASCs cultures promoted the migration and invasion of EPCs and the ability to form capillary-like structures. The expression of multiple angiogenesis markers in EPCs were significantly increased when cocultured with ASCs. In vivo, ASCs combined with EPC promoted vascularization in the fat transplant. Immunofluorescence straining of Edu and CD31 indicated that the Edu labeled EPC did not directly participate in the vascularization inside the fat tissue. CONCLUSIONS: ADSC can participate in the tube formation of EPC although it cannot form canonical capillary structures. Meanwhile, Soluble factors secreted by ASCs promotes the angiogenic potential of EPCs. ASCs paracrine signaling appears to promote angiogenesis by increasing the migration and invasion of EPCs and simultaneously upregulating the expression of angiogenesis markers in EPCs. The results of in vivo experiments showed that ASCs combined with EPCs significantly promote the formation of blood vessels in the fat implant. Remarkably, EPCs may promote angiogenesis by paracrine regulation of endogenous endothelial cells (ECs) rather than direct participation in the formation of blood vessels.

Conquering the cytokine storm in COVID-19-induced ARDS using placenta-derived decidua stromal cells.

Acute respiratory distress syndrome (ARDS) is the most common cause of death in COVID-19 patients. The cytokine storm is the main driver of the severity and magnitude of ARDS. Placenta-derived decidua stromal cells (DSCs) have a stronger immunosuppressive effect than other sources of mesenchymal stromal cells. Safety and efficacy study included 10 patients with a median age of 50 (range 14-68) years with COVID-19-induced ARDS. DSCs were administered 1-2 times at a dose of 1 × 106 /kg. End points were safety and efficacy by survival, oxygenation and effects on levels of cytokines. Oxygenation levels increased from a median of 80.5% (range 69-88) to 95% (range 78-99) (p = 0.012), and pulmonary infiltrates disappeared in all patients. Levels of IL-6 decreased from a median of 69.3 (range 35.0-253.4) to 11 (range 4.0-38.3) pg/ml (p = 0.018), and CRP decreased from 69 (range 5-169) to 6 (range 2-31) mg/ml (p = 0.028). Two patients died, one of a myocardial infarction and the other of multiple organ failure, diagnosed before the DSC therapy. The other patients recovered and left the intensive care unit (ICU) within a median of 6 (range 3-12) days. DSC therapy is safe and capable of improving oxygenation, decreasing inflammatory cytokine level and clearing pulmonary infiltrates in patients with COVID-19.

Transplantation of adipose-derived stromal cells protects functional and morphological auditory nerve integrity in a model of cochlear implantation.

Cochlear implants are considered the gold standard therapy for subjects with severe hearing loss and deafness. Cochlear implants bypass the damaged hair cells and directly stimulate spiral ganglion neurons (SGNs) of the auditory nerve. Hence, the presence of functional SGNs is crucial for speech perception in electric hearing with a cochlear implant. In deaf individuals, SGNs progressively degenerate due to the lack of neurotrophic support, normally provided by sensory cells of the inner ear. Adipose-derived stromal cells (ASCs) are known to produce neurotrophic factors. In a guinea pig model of sensory hearing loss and cochlear implantation, ASCs were autologously transplanted into the scala tympani prior to insertion of a cochlear implant on one side. Electrically evoked auditory brain stem responses (eABR) were recorded 8 weeks after cochlear implantation. At conclusion of the experiment, the cochleae were histologically evaluated. Compared to untreated control animals, transplantation of ASCs resulted in an increased number of SGNs and their peripheral neurites. In ASC-transplanted animals, mean eABR thresholds were lower and suprathreshold amplitudes larger, suggesting a larger population of intact auditory nerve fibers. Moreover, when compared to controls, amplitude-level functions of eABRs in ASC transplanted animals demonstrated steeper slopes in response to increasing interphase gaps (IPGs), indicative of better functionality of the auditory nerve. In summary, results suggest that transplantation of autologous ASCs into the deaf inner ear may have protective effects on the survival of SGNs and their peripheral processes and may thus contribute to long-term benefits in speech discrimination performance in cochlear implant subjects.