Cellular Heterogeneity in Adipose Tissues.

Adipose tissue depots in distinct anatomical locations mediate key aspects of metabolism, including energy storage, nutrient release, and thermogenesis. Although adipocytes make up more than 90% of adipose tissue volume, they represent less than 50% of its cellular content. Here, I review recent advances in genetic lineage tracing and transcriptomics that reveal the identities of the heterogeneous cell populations constituting mouse and human adipose tissues. In addition to mature adipocytes and their progenitors, these include endothelial and various immune cell types that together orchestrate adipose tissue development and functions. One salient finding is the identification of progenitor subtypes that can modulate adipogenic capacity through paracrine mechanisms. Another is the description of fate trajectories of monocyte/macrophages, which can respond maladaptively to nutritional and thermogenic stimuli, leading to metabolic disease. These studies have generated an extraordinary source of publicly available data that can be leveraged to explore commonalities and differences among experimental models, providing new insights into adipose tissues and their role in metabolic disease.

Histone demethylase KDM3B mediates matrix stiffness-induced osteogenic differentiation of adipose-derived stem cells.

Biomechanical signals in the extracellular niche are considered promising for programming the lineage specification of stem cells. Recent studies have reported that biomechanics, such as the microstructure of nanomaterials, can induce adipose-derived stem cells (ASCs) to differentiate into osteoblasts, mediating gene regulation at the epigenetic level. Therefore, in this study, transcriptome expression levels of histone demethylases in ASCs were screened after treatment with different matrix stiffnesses, and histone lysine demethylase 3B (KDM3B) was found to promote osteogenic differentiation of ASCs in response to matrix stiffness, indicating a positive modulatory effect on this biological process. ASCs exhibited widespread and polygonal shapes with a distinct bundle-like expression of vinculin parallel to the axial cytoskeleton along the cell margins on the stiff matrix rather than round shapes with a smeared and shorter expression on the soft matrix. Comparatively rigid polydimethylsiloxane material directed ASCs into an osteogenic phenotype in inductive culture media via the upregulation of osteocalcin, alkaline phosphatase, and runt-related transcription factor 2. Treatment with KDM3B-siRNA decreased the expression of osteogenic differentiation markers and impaired mitochondrial dynamics and mitochondrial membrane potential. These results illustrate the critical role of KDM3B in the biomechanics-induced osteogenic commitment of ASCs and provide new avenues for the further application of stem cells as potential therapeutics for bone regeneration.

GDNF facilitates the differentiation of ADSCs to Schwann cells and enhances nerve regeneration through GDNF/MTA1/Hes1 axis.

Adipose tissue-derived stem cells (ADSCs) are a kind of stem cells with multi-directional differentiation potential, which mainly restore tissue repair function and promote cell regeneration. It can be directionally differentiated into Schwann-like cells to promote the repair of peripheral nerve injury. Glial cell line-derived neurotrophic factor (GDNF) plays an important role in the repair of nerve injury, but the underlying mechanism remains unclear, which seriously limits its further application.The study aimed to identify the molecular mechanism by which overexpression of glial cell line-derived neurotrophic factor (GDNF) facilitates the differentiation of ADSCs into Schwann cells, enhancing nerve regeneration after injury. In vitro, ADSCs overexpressing GDNF for 48 h exhibited changes in their morphology, with 80% of the cells having two or more prominences. Compared with that of ADSCs, GDNF-ADSCs exhibited increased expression of the Schwann cell marker S100, nerve damage repair-related factors.ADSC cells in normal culture and ADSC cells were overexpressing GDNF(GDNF-ADSCs) were analysed using TMT-Based Proteomic Analysis and revealed a significantly higher expression of MTA1 in GDNF-ADSCs than in control ADSCs. Hes1 expression was significantly higher in GDNF-ADSCs than in ADSCs and decreased by MTA1 silencing, along with a simultaneous decrease in the expression of S100 and nerve damage repair factors. These findings indicate that GDNF promotes the differentiation of ADSCs into Schwann cells and induces factors that accelerate peripheral nerve damage repair.

Convergent alteration of the mesenchymal stem cell heterogeneity in adipose tissue during aging.

Adipose-derived stem cells (ASCs) from distinct age groups possess different characteristics; however, the age-associated changes in ASCs heterogenicity remain largely unknown. In this study, several publicly available single-cell RNA sequencing (RNA-seq) data cohorts of inguinal adipose tissues, including young (2 weeks), adult (8 weeks), and old (18 months) C57BL/6 mice, were analyzed. Transcriptomic clustering of integrated single-cell RNA-seq data from different age groups revealed the existence of five ASCs subtypes. Interestingly, ASCs showed a loss of heterogeneity with aging, and ASCs subtype 4 (ASC-4) was the dominant subpopulation accounting for more than 98% of aged ASCs converging to the terminal differentiation state. The multidirectional differentiation potentials of different ASCs subtypes were largely distinct while the adipogenic ability of ASC-4 increased with age persistently. Regulon analysis of ASC subtypes further identified Cebpb as the ASC-4-specific transcription factor, which was known as one of the major adipogenic regulators. Analysis of ligand-receptor pairs between ASCs and other cell types in adipose tissue identified age-associated upregulation of inflammatory responses-associated factors including CCL2 and CCL7. Treatment with 100 ng/mL CCL2 in vitro could significantly promote the adipogenesis of ASCs through enhanced phosphorylation of AKT and decreased expression of ß-catenin. In addition, supplementation of 100 ng/mL CCL7 could significantly increase the expression of inflammatory genes and ASC-4-specific transcriptional factors in 2-week-old ASCs, potentially acting as a driver of ASCs convergence. Our findings help to delineate the complex biological processes of ASCs aging and shed light on better regenerative and therapeutic applications of ASCs.

Recent advances in the use of extracellular vesicles from adipose-derived stem cells for regenerative medical therapeutics.

Adipose-derived stem cells (ADSCs) are a subset of mesenchymal stem cells (MSCs) isolated from adipose tissue. They possess remarkable properties, including multipotency, self-renewal, and easy clinical availability. ADSCs are also capable of promoting tissue regeneration through the secretion of various cytokines, factors, and extracellular vesicles (EVs). ADSC-derived EVs (ADSC-EVs) act as intercellular signaling mediators that encapsulate a range of biomolecules. These EVs have been found to mediate the therapeutic activities of donor cells by promoting the proliferation and migration of effector cells, facilitating angiogenesis, modulating immunity, and performing other specific functions in different tissues. Compared to the donor cells themselves, ADSC-EVs offer advantages such as fewer safety concerns and more convenient transportation and storage for clinical application. As a result, these EVs have received significant attention as cell-free therapeutic agents with potential future application in regenerative medicine. In this review, we focus on recent research progress regarding regenerative medical use of ADSC-EVs across various medical conditions, including wound healing, chronic limb ischemia, angiogenesis, myocardial infarction, diabetic nephropathy, fat graft survival, bone regeneration, cartilage regeneration, tendinopathy and tendon healing, peripheral nerve regeneration, and acute lung injury, among others. We also discuss the underlying mechanisms responsible for inducing these therapeutic effects. We believe that deciphering the biological properties, therapeutic effects, and underlying mechanisms associated with ADSC-EVs will provide a foundation for developing a novel therapeutic approach in regenerative medicine.

Adipose-derived stem cell exosomes loaded with icariin alleviates rheumatoid arthritis by modulating macrophage polarization in rats.

Rheumatoid arthritis (RA) is a chronic autoimmune disease marked by synovitis and cartilage destruction. The active compound, icariin (ICA), derived from the herb Epimedium, exhibits potent anti-inflammatory properties. However, its clinical utility is limited by its water insolubility, poor permeability, and low bioavailability. To address these challenges, we developed a multifunctional drug delivery system-adipose-derived stem cells-exosomes (ADSCs-EXO)-ICA to target active macrophages in synovial tissue and modulate macrophage polarization from M1 to M2. High-performance liquid chromatography analysis confirmed a 92.4 ± 0.008% loading efficiency for ADSCs-EXO-ICA. In vitro studies utilizing cellular immunofluorescence (IF) and flow cytometry demonstrated significant inhibition of M1 macrophage proliferation by ADSCs-EXO-ICA. Enzyme-linked immunosorbent assay, cellular transcriptomics, and real-time quantitative PCR indicated that ADSCs-EXO-ICA promotes an M1-to-M2 phenotypic transition by reducing glycolysis through the inhibition of the ERK/HIF-1α/GLUT1 pathway. In vivo, ADSCs-EXO-ICA effectively accumulated in the joints. Pharmacodynamic assessments revealed that ADSCs-EXO-ICA decreased cytokine levels and mitigated arthritis symptoms in collagen-induced arthritis (CIA) rats. Histological analysis and micro computed tomography confirmed that ADSCs-EXO-ICA markedly ameliorated synovitis and preserved cartilage. Further in vivo studies indicated that ADSCs-EXO-ICA suppresses arthritis by promoting an M1-to-M2 switch and suppressing glycolysis. Western blotting supported the therapeutic efficacy of ADSCs-EXO-ICA in RA, confirming its role in modulating macrophage function through energy metabolism regulation. Thus, this study not only introduces a drug delivery system that significantly enhances the anti-RA efficacy of ADSCs-EXO-ICA but also elucidates its mechanism of action in macrophage function inhibition.

Efficacy of adipose-derived stem cells in preventing peripheral nerve adhesion and promoting nerve regeneration: A laboratory investigation in a rat model.

BACKGROUND: Neurolysis alone or administration of anti-adhesion products after neurolysis is performed to treat peripheral nerve adhesion; however, the recovery of nerve function is poor. This study aimed to investigate the efficacy of adipose-derived stem cells (ADSCs) for peripheral nerve adhesion in a rat model. METHODS: As a nerve adhesion procedure, the neural bed was coagulated, and the epineurium of the sciatic nerve was sutured to the coagulated neural bed using nylon. Neurolysis was performed 6 weeks after the nerve adhesion procedure, and saline (control group) or ADSCs (ADSC group) were administered around the nerve where neurolysis was performed. Evaluations were performed 6 weeks after the administration. RESULTS: The wet weight ratio of the tibialis anterior muscle and nerve conduction velocity, which are indicators of nerve regeneration, were significantly better, while tensile strength, which is an indicator of the severity of nerve adhesion, was significantly lower in the ADSC group than in the control group. In the nerve, the expression of interleukin-10 and transforming growth factor-ß in the nerve was significantly higher and that of tumor necrosis factor-α was significantly lower in the ADSC group than in the control group. Furthermore, significantly fewer M1 macrophages and significantly more M2 macrophages were observed in the ADSC group than in the control group. In the perineural scar, significantly fewer perineural collagen fibers and significantly more vascularization were observed in the ADSC group than in the control group. CONCLUSIONS: ADSCs prevented peripheral nerve adhesion by reducing perineural scarring and enhancing vascularization. Additionally, ADSCs promoted nerve regeneration by decreasing inflammatory cytokine levels and increasing anti-inflammatory cytokine levels, as ADSCs regulated macrophage polarization from M1 to M2 macrophages. These findings hold promise for using ADSCs to treat nerve adhesion.

In Vitro Study of Thymosin Beta 4 Promoting Transplanted Fat Survival by Regulating Adipose-Derived Stem Cells.

BACKGROUND: Autologous fat grafting (AFG) has emerged as a highly sought-after plastic surgery procedure, although its success has been hampered by the uncertain fat survival rate. Current evidence suggests that adipose-derived stem cells (ADSCs) may contribute to fat retention in AFG. In previous studies, it was confirmed that thymosin beta 4 (Tß4) could enhance fat survival in vivo, although the precise mechanism remains unclear. METHODS: ADSCs were isolated from patients undergoing liposuction and their proliferation, apoptosis, anti-apoptosis, and migration were analyzed under Tß4 stimulation using cell counting kit-8, flow cytometry, wound healing assay, and real-time quantitative PCR. The mRNA levels of genes relating to angiogenesis and Hippo signaling were also determined. RESULTS: Tß4 at 100 ng/mL (p-value = 0.0171) and 1000 ng/mL (p-value = 0.0054) significantly increased ADSC proliferation from day 1 compared to the control group (0 ng/mL). In addition, the mRNA levels of proliferation-associated genes were elevated in the Tß4 group. Furthermore, Tß4 enhanced the anti-apoptotic ability of ADSCs when stimulated with Tß4 and an apoptotic induction reagent (0 ng/mL vs. 1000 ng/mL, p-value = 0.011). Crucially, the mRNA expression levels of angiogenesis-related genes and critical genes in the Hippo pathway were affected by Tß4 in ADSCs. CONCLUSIONS: Tß4 enhances adipose viability in AFG via facilitating ADSC proliferation and reducing apoptosis, and acts as a crucial positive regulator of ADSC-associated angiogenesis. Additionally, Tß4 could be accountable for the phenotypic adjustment of ADSCs by regulating the Hippo pathway. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Exosomal IRF1-loaded rat adipose-derived stem cell sheet contributes to wound healing in the diabetic foot ulcers.

BACKGROUND: Cell-based therapy has been recognized as a novel technique for the management of diabetic foot ulcers, and cell-sheet engineering leads to improved efficacy in cell transplantation. This study aims to explore the possible molecular mechanism of the rat adipose-derived stem cell (ASC) sheet loaded with exosomal interferon regulatory factor 1 (IRF1) in foot wound healing. METHODS: Rats were rendered diabetic with streptozotocin, followed by measurement of miR-16-5p expression in wound tissues. Relationship between IRF1, microRNA (miR)-16-5p, and trans-acting transcription factor 5 (SP5) was analyzed using luciferase activity, RNA pull-down, and chromatin immunoprecipitation assays. IRF1 was overexpressed in rat ASCs (rASCs) or loaded onto the rASC sheet, and then exosomes were extracted from rASCs. Accordingly, we assessed the effects of IRF1-exosome or IRF1-rASC sheet on the proliferation and migration of the fibroblasts along with endothelial cell angiogenesis. RESULTS: miR-16-5p was poorly expressed in the wound tissues of diabetic rats. Overexpression of miR-16-5p promoted fibroblast proliferation and migration as well as endothelial cell angiogenesis, thus expediting wound healing. IRF1 was an upstream transcription factor that could bind to the miR-16-5p promoter and increase its expression. In addition, SP5 was a downstream target gene of miR-16-5p. IRF1-exosome from rASCs or the IRF1-rASC sheet facilitated the foot wound healing in diabetic rats through miR-16-5p-dependent inhibition of SP5. CONCLUSION: The present study demonstrates that exosomal IRF1-loaded rASC sheet regulates miR-16-5p/SP5 axis to facilitate wound healing in diabetic rats, which aids in development of stem cell-based therapeutic strategies for diabetic foot wounds.

Adipose-derived stem cells show hepatic differentiation potential and therapeutic effect in rats with acute liver failure.

Hepatocyte transplantation contributes to the repair of liver damage, but hepatocyte resources are limited, making it difficult for this to become a routine treatment. Previous studies have confirmed that mesenchymal stem cells (MSCs) can be induced to differentiate into hepatocyte-like cells (HLCs) by adding different cytokine combinations in vitro, and they then play some roles of hepatocytes. Our previous studies found that the differentiation ability of stem cells is closely related to the origin of the tissue. To identify the mesenchymal stem cells that are most suitable for hepatic differentiation and the treatment of liver failure, we use a three-phase induction process in which human adipose-derived stem cells (hADSCs) and umbilical cord mesenchymal stem cells (hUCMSCs) are induced to differentiate towards HLCs in vitro, and rats with acute liver failure (ALF) induced by D-gal are cured by MSCs and MSC-derived HLCs (MSCs-HLC), respectively. We find that hADSCs are stronger than hUCMSCs in hepatic differentiation ability, and they have a better curative effect when using hADSCs-HLC or jointly using hADSCs and hADSCs-HLC, which has positive significance for hepatocyte regeneration, recovery of liver function and reduction of systemic inflammatory reaction, finally improving the survival rate of rats with acute liver failure.

Current perspectives on cell-assisted lipotransfer for breast cancer patients after radiotherapy.

BACKGROUND: Cell-assisted lipotransfer (CAL), a technique of autologous adipose transplantation enriched with adipose-derived stem cells (ADSCs), has the potential to improve cosmetic outcomes at irradiated sites. However, many concerns have been raised about the possibility of ADSCs increasing oncological risk in cancer patients. With the increasing demand for CAL reconstruction, there is an urgent need to determine whether CAL treatment could compromise oncological safety after radiotherapy, as well as to evaluate its efficacy in guiding clinical decisions. METHODS: A PRISMA-compliant systematic review of the safety and efficacy of CAL in breast cancer patients after radiotherapy was conducted. The PubMed, Ovid, Cochrane Library, and ClinicalTrials.gov databases were comprehensively searched from inception to 31 December 2021. RESULTS: The search initially yielded 1185 unique studies. Ultimately, seven studies were eligible. Based on the limited outcome evidence, CAL did not increase recurrence risk in breast cancer patients but presented aesthetic improvement and higher volumetric persistence in a long-term follow-up. Although breast reconstruction with CAL also had oncological safety after radiotherapy, these patients needed more adipose tissue and had relatively lower fat graft retention than the non-irradiated patients (P < 0.05). CONCLUSIONS: CAL has oncological safety and does not increase recurrence risk in irradiated patients. Since CAL doubles the amount of adipose required without significantly improving volumetric persistence, clinical decisions for irradiated patients should be made more cautiously to account for the potential costs and aesthetic outcomes. There is limited evidence at present; thus, higher-quality, evidence-based studies are required to establish a consensus on breast reconstruction with CAL after radiotherapy.

An Atlas of Promoter Chromatin Modifications and HiChIP Regulatory Interactions in Human Subcutaneous Adipose-Derived Stem Cells.

The genome of human adipose-derived stem cells (ADSCs) from abdominal and gluteofemoral adipose tissue depots are maintained in depot-specific stable epigenetic conformations that influence cell-autonomous gene expression patterns and drive unique depot-specific functions. The traditional approach to explore tissue-specific transcriptional regulation has been to correlate differential gene expression to the nearest-neighbor linear-distance regulatory region defined by associated chromatin features including open chromatin status, histone modifications, and DNA methylation. This has provided important information; nonetheless, the approach is limited because of the known organization of eukaryotic chromatin into a topologically constrained three-dimensional network. This network positions distal regulatory elements in spatial proximity with gene promoters which are not predictable based on linear genomic distance. In this work, we capture long-range chromatin interactions using HiChIP to identify remote genomic regions that influence the differential regulation of depot-specific genes in ADSCs isolated from different adipose depots. By integrating these data with RNA-seq results and histone modifications identified by ChIP-seq, we uncovered distal regulatory elements that influence depot-specific gene expression in ADSCs. Interestingly, a subset of the HiChIP-defined chromatin loops also provide previously unknown connections between waist-to-hip ratio GWAS variants with genes that are known to significantly influence ADSC differentiation and adipocyte function.

Exosome derived from human adipose-derived stem cell improve wound healing quality: A systematic review and meta-analysis of preclinical animal studies.

Excellent capability of exosome derived from human adipose-derived stem cell (ADSC) manifested in improving the quality of wound healing with SMD (STD Mean Difference). However, it is still in the preclinical stage and its efficacy remains uncertain. Emphasised the need for a systematic review of preclinical studies to the validity of it in ameliorate wound healing quality which accelerate the clinical application translation. We performed a systematic literature review to identify all published controlled and intervention studies comparing exosome derived from human ADSC with placebo in animal models of wound closure during wound healing. PubMed, Embase and Cochrane were employed. Risk of bias assessed by the SYRCLE tool aimed at preclinical animal studies. Administration of exosome derived from human ADSC extremely improved wound closure compared with controls, which is primary outcome (SMD 1.423, 95% confidence interval (CI) 1.137-1.709 P < .001), the same effect as ADSC. The therapeutic effect is further enhanced by modified ADSC-EV. Other outcomes: density and the number of blood vessels: (SMD 1.593 95% CI 1.007-2.179 P < .001)；Fibrosis-related protein expression was highly expressed in the early term of wound healing, decreased in shaping period, which automatically regulates wound collagen deposition. Scar size, number of fibroblast and epithelial cell migration and proliferation expressed were ranked as follows: modified adipose stem cell exosomes > adipose stem cell exosomes > controls. Exosome derived from human ADSC, especially after enrichment for specific non-coding RNA, is a promising approach to improve healing efficiency.

3D-cultured small size adipose-derived stem cell spheroids promote bone regeneration in the critical-sized bone defect rat model.

Adipose-derived stem cells (ADSCs), due to their regenerative ability, have beneficial effects on bone and cartilage defects. In addition, spheroid formation of ADSCs obtained using three-dimensional (3D) culture accelerates the regenerative ability of ADSCs. The study investigated the regenerative effect of 3D-cultured small size ADSC spheroids without a scaffold in rats with defects in the critical-sized calvarial bone. ADSC-single cells, ADSC-spheroids, or PBS (as control) were implanted in rats, and radiological and histological assessment of bone regeneration was performed. Bone defects were significantly regenerated in the ADSC-spheroid group compared to that in the control group. ADSC-spheroids also showed the most significant bone regeneration in histological assessment. Immunohistochemistry assessment showed that ADSC-spheroids could survive 12 weeks after cell implantation. In vitro, cell apoptosis in ADSC-spheroids was significantly suppressed compared to that in ADSC-single cells. In addition, gene expression related to bone morphogenesis, angiogenesis, and stemness in ADSC-spheroids was elevated. The scaffold-free 3D-cultured small ADSC-spheroids survived in in vitro and in vivo conditions and promoted bone regeneration. Therefore, injectable small size ADSC-spheroids are a novel and less-invasive therapeutic option for treating bone defects.

Knee Loading Enhances the Migration of Adipose-Derived Stem Cells to the Osteoarthritic Sites Through the SDF-1/CXCR4 Regulatory Axis.

Osteoarthritis (OA) is a whole joint disorder that is characterized by cartilage damage and abnormal remodeling of subchondral bone. Injecting adipose-derived stem cells (ASCs) into the knee joint cavity can assist in repairing osteoarthritic joints, but their ability to migrate to the damaged site is limited. Our previous studies have shown that knee loading can improve the symptoms of OA, but the effect and mechanism of knee loading on the migration of ASCs in OA remain unclear. We employed a mouse model of OA in the knee and applied knee loading (1 N at 5 Hz for 6 min/day for 2 weeks) after the intra-articular injection of ASCs. The cartilage and subchondral bone repair were assessed by histopathological analysis. Immunofluorescence assays were also used to analyze the migration of ASCs. Using cell cultures, we evaluated the migration of ASCs using the transwell migration and wound healing assays. In vivo experiments showed that knee loading promoted the migration of ASCs, increased the local SDF-1 level, and accelerated the repair of the OA-damaged sites. Mechanistically, the observed effects were blocked by the SDF-1/CXCR4 inhibitor. The in vitro results further revealed that knee loading promoted the migration of ASCs and the inhibition of SDF-1/CXCR4 significantly suppressed the beneficial loading effect. The results herein suggested that the migration of ASCs was enhanced by knee loading through the SDF-1/CXCR4 regulatory axis, and mechanical loading promoted the joint-protective effect of ASCs.

The secretome obtained under hypoxic preconditioning from human adipose-derived stem cells exerts promoted anti-apoptotic potentials through upregulated autophagic process.

BACKGROUND: Hypoxic preconditioning (HP) is a stem cell preconditioning modality designed to augment the therapeutic effects of mesenchymal stem cells (MSCs). Although autophagy is expected to play a role in HP, very little is known regarding the relationship between HP and autophagy. METHODS AND RESULTS: The adipose-derived stem cell (ASC)-secretome obtained under normoxia (NCM) and ASC-secretome obtained under HP (HCM) were obtained by culturing ASCs for 24 h under normoxic (21% partial pressure of O2) and hypoxic (1% partial pressure of O2) conditions, respectively. Subsequently, to determine the in vivo effects of HCM, each secretome was injected into 70% partially hepatectomized mice, and liver specimens were obtained. HCM significantly reduced the apoptosis of thioacetamide-treated AML12 hepatocytes and promoted the autophagic processes of the cells (P < 0.05). Autophagy blockage by either bafilomycin A1 or ATG5 siRNA significantly abrogated the anti-apoptotic effect of HCM (P < 0.05), demonstrating that HCM exerts its anti-apoptotic effect by promoting autophagy. The effect of HCM - reduction of cell apoptosis and promotion of autophagic process - was also demonstrated in a mouse model. CONCLUSIONS: HP appears to induce ASCs to release a secretome with enhanced anti-apoptotic effects by promoting the autophagic process of ASCs.

Dose-dependent dominance: How cell densities design stromal cell functions during soft tissue healing.

Regular soft tissue healing relies on the well-organized interaction of different stromal cell types with endothelial cells. However, spatiotemporal conditions might provoke high densities of one special stromal cell type, potentially leading to impaired healing. Detailed knowledge of the functions of rivaling stromal cell types aiming for tissue contraction and stabilization as well as vascular support is mandatory. By the application of an in vitro approach comprising the evaluation of cell proliferation, cell morphology, myofibroblastoid differentiation, and cytokine release, we verified a density-dependent modulation of these functions among juvenile and adult fibroblasts, pericytes, and adipose-derived stem cells during their interaction with microvascular endothelial cells in cocultures. Results indicate that juvenile fibroblasts rather support angiogenesis via paracrine regulation at the early stage of healing, a role potentially compromised in adult fibroblasts. In contrast, pericytes showed a more versatile character aiming at angiogenesis, vessel stabilization, and tissue contraction. Such a universal character was even more pronounced among adipose-derived stem cells. The explicit knowledge of the characteristic functions of stromal cell types is a prerequisite for the development of new analytical and therapeutic approaches for impaired soft tissue healing. The present study delivers new considerations concerning the roles of rivaling stromal cell types within a granulation tissue, pointing to extraordinary properties of pericytes and adipose-derived stem cells.

Genetic and cytometric analyses of subcutaneous adipose tissue in patients with hemophilia and HIV-associated lipodystrophy.

BACKGROUND: The authors recently performed plastic surgeries for a small number of patients with hemophilia, HIV infection, and morphologic evidence of lipodystrophy. Because the pathophysiological mechanism of HIV-associated lipodystrophy remains to be elucidated, we analyzed subcutaneous adipose tissues from the patients. METHODS: All six patients had previously been treated with older nucleoside analogue reverse-transcriptase inhibitors (NRTIs; stavudine, didanosine or zidovudine). Abdominal and inguinal subcutaneous fat samples were obtained from the HIV+ patients with hemophilia and HIV- healthy volunteers (n = 6 per group), and analyzed via DNA microarray, real-time PCR, flow cytometry and immunohistochemistry. RESULTS: The time from initial NRTI treatment to collecting samples were 21.7 years in average. Cytometric analysis revealed infiltration of inflammatory M1 macrophages into HIV-infected adipose tissue and depletion of adipose-derived stem cells, possibly due to exhaustion following sustained adipocyte death. Genetic analysis revealed that adipose tissue from HIV+ group had increased immune activation, mitochondrial toxicity, chronic inflammation, progressive fibrosis and adipocyte dysfunction (e.g. insulin resistance, inhibited adipocyte differentiation and accelerated apoptosis). Of note, both triglyceride synthesis and lipolysis were inhibited in adipose tissue from patients with HIV. CONCLUSIONS: Our findings provide important insights into the pathogenesis of HIV-associated lipodystrophy, suggesting that fat redistribution may critically depend on adipocytes' sensitivity to drug-induced mitochondrial toxicity, which may lead either to atrophy or metabolic complications.

G protein-coupled estrogen receptor 1 mediates proliferation and adipogenic differentiation of goat adipose-derived stem cells through ERK1/2-NF-κB signaling pathway.

Adipose tissue formation and moderate fat deposition are important for the production performance and eating quality of livestock meats. The self-renewal and adipogenic differentiation of adipose-derived stem cells are responsible for the formation and development of adipose tissue. In addition, estrogen targeting G protein-coupled estrogen receptor 1 (GPER1) has been reported to modulate cell proliferation and differentiation during tissue and organ development. However, the potential correlation among estrogen, GPER1, proliferation, and adipogenic differentiation in goat adipose-derived stem cells (gADSCs) is still unclear. Herein, we demonstrated that 17ß-estradiol enhances the proliferative ability of gADSCs, indicated by the increased cell number and cell viability, accompanied by up-regulated expressions of cyclin D1 and PCNA. Meanwhile, the adipogenic differentiation is promoted by 17ß-estradiol, supported by higher ccumulation of intracellular lipids and increased expressions of PPARγ, ACC, and FABP4. Notably, these activities are all obviously reduced by administration with GPER1 antagonist G15, but GPER1 agonist G1 enhances cell proliferation and adipogenic differentiation. Moreover, GPER1 silencing diminishes cell proliferation and adipogenic differentiation. In parallel, 17ß-estradiol elevates the protein level of nuclear p-p65. Furthermore, the phosphorylation of p65 is enhanced by G1 but inhibited by G15 and GPER1 silencing. In addition, the phosphorylation of p65 is mediated by ERK1/2, suggesting that estrogen targeting GPER1 regulates cell proliferation and adipogenic differentiation of gADSCs through the ERK1/2-NF-κB signaling pathway. This study may provide a strong theoretical basis for improving meat quality, flavor, and cold resistance of livestock.

GABA-stimulated adipose-derived stem cells suppress subcutaneous adipose inflammation in obesity.

Accumulating evidence suggests that subcutaneous and visceral adipose tissues are differentially associated with metabolic disorders. In obesity, subcutaneous adipose tissue is beneficial for metabolic homeostasis because of repressed inflammation. However, the underlying mechanism remains unclear. Here, we demonstrate that γ-aminobutyric acid (GABA) sensitivity is crucial in determining fat depot-selective adipose tissue macrophage (ATM) infiltration in obesity. In diet-induced obesity, GABA reduced monocyte migration in subcutaneous inguinal adipose tissue (IAT), but not in visceral epididymal adipose tissue (EAT). Pharmacological modulation of the GABAB receptor affected the levels of ATM infiltration and adipose tissue inflammation in IAT, but not in EAT, and GABA administration ameliorated systemic insulin resistance and enhanced insulin-dependent glucose uptake in IAT, accompanied by lower inflammatory responses. Intriguingly, compared with adipose-derived stem cells (ADSCs) from EAT, IAT-ADSCs played key roles in mediating GABA responses that repressed ATM infiltration in high-fat diet-fed mice. These data suggest that selective GABA responses in IAT contribute to fat depot-selective suppression of inflammatory responses and protection from insulin resistance in obesity.