Adipose-derived stem cells: Sources, potency, and implications for regenerative therapies

Advanced methods to mechanically isolate stromal vascular fraction: A concise review

Adipose tissue is a highly attractive reservoir of stem cells due to its accessibility and abundance, and the SVF within it holds great promise for stem cell-based therapies. The use of mechanical methods for SVF isolation from adipose tissue is preferred over enzymatic methods, as it can be readily applied in clinical settings without additional processing steps. However, there is a lack of consensus on the optimal approach for mechanically isolating SVF. This comprehensive review aims to present and compare the latest mechanical isolation methods for SVF from adipose tissue, including centrifugation, filtration/washing, emulsification, vibration, and mincing/adiponizing. Each of these methods possesses unique advantages and limitations, and yet, no conclusive evidence has emerged demonstrating the superiority of one approach over the others, primarily due to the dearth of well-controlled prospective studies in this field.

Exercise training-driven exosomal miRNA-323-5p activity suppresses adipogenic conversion of 3T3-L1 cells via the DUSP3/ERK pathway

Adipose-derived stem cell (ASC)-released exosomes (ASCexos) have multiple biological activities. We examined the effect of ASCexos derived from the inguinal adipose tissue of exercise-trained rats (EX-ASCexos) on adipogenic conversion of 3T3-L1 cells and analyzed their microRNA (miRNA) expression profiles. Differentiation of 3T3-L1 cells into adipocytes was performed for 9 d with EX-ASCexos or ASCexos from sedentary control rats (SED-ASCexos), and the expression of proteins and miRNA involved in adipogenic differentiation were determined. EX-ASCexos but not SED-ASCexos attenuated 3T3-L1 adipocyte differentiation with increased phosph-Ser112PPARγ expression, the inactive form of PPARγ. These differentiated adipocytes were also accompanied by increased phosph-Thr202/Tyr204ERK and decreased dual-specificity phosphatase 3 (DUSP3) levels. The exosomal miRNAs miR-323-5p, miR-433-3p, and miR-874-3p were identified specifically in EX-ASCexos. Of these, miR-323-5p mimic replicated the EX-ASCexo-induced suppression of 3T3-L1 adipocyte differentiation and altered adipogenesis-related factor expression. In conclusion, exercise training-driven exosomal miR-323-5p suppressed 3T3-L1 adipogenesis by increasing phosph-Ser112PPARγ expression, while phosph-Thr202/Tyr204ERK accumulation inhibited DUSP3 expression.

Isolation and Characterization of Canine Adipose-Derived Mesenchymal Stromal Cells: Considerations in Translation from Laboratory to Clinic

In allogeneic MSC implantation, the cells are isolated from a donor different from the recipient. When tested, allogeneic MSCs have several advantages over autologous ones: faster cell growth, sufficient cell concentration, and readily available cells for clinics. To ensure the safe and efficient use of allogeneic MSCs in clinics, the MSCs need to be first tested in vitro. With this study, we paved the way by addressing the in vitro aspects of canine adipose-derived MSCs, considering the limited studies on the clinical use of canine cells. We isolated cAD-MSCs from canine falciform ligament fat and evaluated their viability and proliferation using an MTS assay. Then, we characterized the MSC-specific antigens using immunophenotyping and immunofluorescence and demonstrated their potential for in vitro differentiation. Moreover, we established shipping and cryobanking procedures to lead the study to become an off-the-shelf therapy. During expansion, the cells demonstrated a linear increase in cell numbers, confirming their proliferation quantitatively. The cells showed viability before and after cryopreservation, demonstrating that cell viability can be preserved. From a clinical perspective, the established shipping conditions demonstrated that the cells retain their viability for up to 48 h. This study lays the groundwork for the potential use of allogeneic cAD-MSCs in clinical applications.

Impact of compression forces on different mesenchymal stem cell types regarding orthodontic indication

The potential of stem cells, for example upper periodontal ligament stem cells from the maxilla (u-PDLSC) and from the mandible (l-PDLSC), adipose-derived mesenchymal stem cells (AD-MSC), and bone marrow-derived mesenchymal stem cells (BM-MSC), with respect to periodontal remodeling and orthodontic treatment is of great importance. In this work, we focus on the comprehensive adaptability of different stem cell types to mechanical forces with the aim to better understanding cell behavior and to refine a new mechanistic approach to investigate periodontal remodeling. We comprehensively analyze stem cells and observe distinct morphological and proliferation changes under compression in dependence on stem cell type. The cell signaling of extracellular signal-regulated kinase (ERK) and protein kinase B, also called AKT, and their respective phosphorylation shows diverse responses to compression. Additionally, vascular endothelial growth factor and hepatocyte growth factor secretion were reduced under mechanical stress in all cell types, with cell-specific variations. Osteoprotegerin secretion was reduced under compression, particularly in u-PDLSC. At least, diverse soluble receptors of NF-kB-ligand secretion patterns among cell types under pressure were observed, providing crucial insights into bone metabolism. These findings offer a deeper understanding of the behavior of mesenchymal stem cells under mechanical stimuli, highlighting their roles in bone remodeling, wound healing, and tissue regeneration in orthodontic and regenerative medicine contexts. Our results underscore the potential of u-PDLSC, l-PDLSC, and AD-MSC in periodontal regeneration, with AD-MSC showing notable resilience under compression, indicating its promising role for further investigation for orthodontic research. While these findings are encouraging, further research is essential to fully comprehend the mechanism of stem cell-based periodontal therapies.

Development of magnesium hydroxide-doped nanofibrous spheres for repairing infected skin wounds

The healing of skin wounds is a continuous and coordinated process, typically accompanied by microbial colonization and growth. This may result in wound infection and subsequent delay in wound healing. Therefore, it is of particular importance to inhibit the growth of microorganisms in the wound environment. In this study, magnesium hydroxide-doped polycaprolactone (PCL/MH) nanofibrous spheres were fabricated by electrospinning and electrospray techniques to investigate their effects on infected wound healing. The prepared PCL/MH nanofibrous spheres had good porous structure and biocompatibility, providing a favorable environment for the delivery and proliferation of adipose stem cells. The incorporation of MH significantly enhanced the antimicrobial properties of the spheres, in particular, the inhibition of the growth of S. aureus and E. coli. We showed that such PCL/MH nanofibrous spheres had good antimicrobial properties and effectively promoted the regeneration of infected wound tissues, which provided a new idea for the clinical treatment of infected wounds.

Advancements in seawater immersion wound management: Current treatments and innovations

With advancements in naval warfare, the number and severity of seawater injuries have skyrocketed, necessitating effective seawater immersion (SWI) wound management. The unique marine pathogens, salinity, low temperature and alkalinity of seawater are the main environmental factors that can influence SWI wound healing. The current treatment strategy for SWI wounds follows a standard protocol based on terrestrial wound conditions, neglecting seawater conditions. The key requirements for ideal SWI treatment include good adhesion to the wound surface to minimize further exposure to seawater, enhanced wound healing properties to minimize wound healing time and antibacterial properties to prevent infections from marine pathogens. Current SWI wound-specific treatments range from elaborate techniques like vacuum-sealed drainage and vacuum-assisted closure for severe blast injuries to simple application of hydrogels or collagen dressings for minor injuries. This review discusses the current status and development of various treatment modalities for SWI wounds. The development of these treatment strategies and an understanding of their mechanisms of action make us better prepared to manage and treat SWI injuries.

Directed Differentiation of Adipose-Derived Stem Cells Using Imprinted Cell-Like Topographies as a Growth Factor-Free Approach

The influence of surface topography on stem cell behavior and differentiation has garnered significant attention in regenerative medicine and tissue engineering. The cell-imprinting method has been introduced as a promising approach to mimic the geometry and topography of cells. The cell-imprinted substrates are designed to replicate the topographies and dimensions of target cells, enabling tailored interactions that promote the differentiation of stem cells towards desired specialized cell types. In fact, by replicating the size and shape of cells, biomimetic substrates provide physical cues that profoundly impact stem cell differentiation. These cues play a pivotal role in directing cell morphology, cytoskeletal organization, and gene expression, ultimately influencing lineage commitment. The biomimetic substrates' ability to emulate the native cellular microenvironment supports the creation of platforms capable of steering stem cell fate with high precision. This review discusses the role of mechanical factors that impact stem cell fate. It also provides an overview of the design and fabrication principles of cell-imprinted substrates. Furthermore, the paper delves into the use of cell-imprinted polydimethylsiloxane (PDMS) substrates to direct adipose-derived stem cells (ADSCs) differentiation into a variety of specialized cells for tissue engineering and regenerative medicine applications. Additionally, the review discusses the limitations of cell-imprinted PDMS substrates and highlights the efforts made to overcome these limitations.

Meflin/ISLR is a marker of adipose stem and progenitor cells in mice and humans that suppresses white adipose tissue remodeling and fibrosis

Identifying specific markers of adipose stem and progenitor cells (ASPCs) in vivo is crucial for understanding the biology of white adipose tissues (WAT). PDGFRα-positive perivascular stromal cells represent the best candidates for ASPCs. This cell lineage differentiates into myofibroblasts that contribute to the impairment of WAT function. However, ASPC marker protein(s) that are functionally crucial for maintaining WAT homeostasis are unknown. We previously identified Meflin as a marker of mesenchymal stem cells (MSCs) in bone marrow and tissue-resident perivascular fibroblasts in various tissues. We also demonstrated that Meflin maintains the undifferentiated status of MSCs/fibroblasts. Here, we show that Meflin is expressed in WAT ASPCs. A lineage-tracing experiment showed that Meflin+ ASPCs proliferate in the WAT of obese mice induced by a high-fat diet (HFD), while some of them differentiate into myofibroblasts or mature adipocytes. Meflin knockout mice fed an HFD exhibited a significant fibrotic response as well as increases in adipocyte cell size and the number of crown-like structures in WAT, accompanied by impaired glucose tolerance. These data suggested that Meflin expressed by ASPCs may have a role in reducing disease progression associated with WAT dysfunction.

Single-cell RNA-seq in diabetic foot ulcer wound healing

Diabetic foot ulcer (DFU) is a chronic and serious complication of diabetes mellitus. It is mainly caused by hyperglycaemia, diabetic peripheral vasculopathy and diabetic peripheral neuropathy. These conditions result in ulceration of foot tissues and chronic wounds. If left untreated, DFU can lead to amputation or even endanger the patient's life. Single-cell RNA sequencing (scRNA-seq) is a technique used to identify and characterise transcriptional subpopulations at the single-cell level. It provides insight into cellular function and the molecular drivers of disease. The objective of this paper is to examine the subpopulations, genes and molecules of cells associated with chronic wounds of diabetic foot by using scRNA-seq. The paper aims to explore the wound-healing mechanism of DFU from three aspects: inflammation, angiogenesis and extracellular matrix remodelling. The goal is to gain a better understanding of the mechanism of DFU wound healing and identify possible DFU therapeutic targets, providing new insights for the application of DFU personalised therapy.

Subcutaneous adipose tissue: Implications in dermatological diseases and beyond

Subcutaneous adipose tissue (SAT) is the deepest component of the three-layered cutaneous integument. While mesenteric adipose tissue-based immune processes have gained recognition in the context of the metabolic syndrome, SAT has been traditionally considered primarily for energy storage, with less attention to its immune functions. SAT harbors a reservoir of immune and stromal cells that significantly impact metabolic and immunologic processes not only in the skin, but even on a systemic level. These processes include wound healing, cutaneous and systemic infections, immunometabolic, and autoimmune diseases, inflammatory skin diseases, as well as neoplastic conditions. A better understanding of SAT immune functions in different processes, could open avenues for novel therapeutic interventions. Targeting SAT may not only address SAT-specific diseases but also offer potential treatments for cutaneous or even systemic conditions. This review aims to provide a comprehensive overview on SAT's structure and functions, highlight recent advancements in understanding its role in both homeostatic and pathological conditions within and beyond the skin, and discuss the main questions for future research in the field.

The Myofibroblast Fate of Therapeutic Mesenchymal Stromal Cells: Regeneration, Repair, or Despair?

Mesenchymal stromal cells (MSCs) can be isolated from various tissues of healthy or patient donors to be retransplanted in cell therapies. Because the number of MSCs obtained from biopsies is typically too low for direct clinical application, MSC expansion in cell culture is required. However, ex vivo amplification often reduces the desired MSC regenerative potential and enhances undesired traits, such as activation into fibrogenic myofibroblasts. Transiently activated myofibroblasts restore tissue integrity after organ injury by producing and contracting extracellular matrix into scar tissue. In contrast, persistent myofibroblasts cause excessive scarring-called fibrosis-that destroys organ function. In this review, we focus on the relevance and molecular mechanisms of myofibroblast activation upon contact with stiff cell culture plastic or recipient scar tissue, such as hypertrophic scars of large skin burns. We discuss cell mechanoperception mechanisms such as integrins and stretch-activated channels, mechanotransduction through the contractile actin cytoskeleton, and conversion of mechanical signals into transcriptional programs via mechanosensitive co-transcription factors, such as YAP, TAZ, and MRTF. We further elaborate how prolonged mechanical stress can create persistent myofibroblast memory by direct mechanotransduction to the nucleus that can evoke lasting epigenetic modifications at the DNA level, such as histone methylation and acetylation. We conclude by projecting how cell culture mechanics can be modulated to generate MSCs, which epigenetically protected against myofibroblast activation and transport desired regeneration potential to the recipient tissue environment in clinical therapies.

Adipose-derived stem cells transplantation improves survival and alleviates contraction of skin grafts via promoting macrophages M2 polarization

BACKGROUND

Full-thickness skin grafts are widely used in plastic and reconstructive surgery. The main limitation of skin grafting is the poor textural durability and associated contracture, which often needs further corrective surgery. Excessive inflammation is the main reason for skin graft contractions, which involve overactivation of myofibroblasts. These problems have prompted the development of new therapeutic approaches, including macrophage polarization modulation and stem cell-based therapies. Currently, adipose-derived stem cells (ASCs) have shown promise in promoting skin grafts survival and regulating macrophage phenotypes. However, the roles of ASCs on macrophages in decreasing skin grafts contraction remain unknown.

MATERIALS AND METHODS

Rat adipose-derived stem cells (rASCs) were isolated from rat inguinal adipose tissues. Full-thickness skin graft model was constructed on male rats divided into control group and rASCs treatment group. Skin graft was assessed for concentration, elasticity modulus and stiffness. Rat bone marrow-derived macrophages (rBMDMs) were isolated from rat femurs, and subsequent RT-qPCR and coculture assays were carried out to explore the cellular mechanisms. Immunohistochemical and immunofluorescence staining were used to verify mechanisms in vivo.

RESULTS

In vivo results showed that after injection of ASCs, improved texture, increased survival and inhibited contraction of skin grafts were seen. Vascularization was also improved as illustrated by laser perfusion image and vascular endothelial growth factor (VEGF) concentration. Histological analysis revealed that ASCs injection significantly reduced expression of pro-inflammatory cytokines (TNF-a, IL-1β) and increased expression of anti-inflammatory (IL-10) and pro-healing cytokines (IGF-1). At cellular level, after co-culturing with rASCs, rat bone marrow derived macrophages (rBMDMs) favored M2 polarization even under inflammatory stimulus.

CONCLUSION

ASCs treatment enhanced vascularization via angiogenic cytokines secretion and alleviated inflammatory environment in skin grafts by driving M2 macrophages polarization, which improved survival and decreased skin grafts contraction. Our work showed that ASCs transplantation can be harnessed to enhance therapeutic efficacy of skin grafting in cutaneous defects treatment.

Hsa-miR-15b-5p/miR-195-5p Controls Osteogenic Differentiation of Human Adipose-Derived Mesenchymal Stem Cells Through Regulating Indian Hedgehog Expression

Osteoblastogenesis is regulated by several signaling pathways like hedgehog signaling. Of three types of mammalian Hedgehog genes, the Indian Hedgehog (Ihh) plays an important role in the formation of the skeleton. Mesenchymal stem cells (MSCs) isolated from adipose tissue have been considered a good source of osteoblast differentiation. Evidence also suggests that miRNAs play an important role in regulating key stages of osteoblast differentiation. In this study, two miRNAs targeting the Ihh were predicted by using bioinformatics analysis. ASCs were successfully derived, purified, and characterized from human adipose tissue. ASCs were chemically induced into osteoblast cells. Then, differentiation was confirmed by alkaline phosphatase (ALP) activity and Alizarin red staining. The relative expression of Ihh and related miRNAs was evaluated after 0, 7, 14, and 21 from the differentiation duration. The results of bioinformatics data showed that has-miR-195-5p and has-miR-15b-5p target the Ihh gene. The expression of Ihh significantly increased in a time-dependent manner in the differentiation process. In contrast, miR-195-5p and miR-15b-5p were significantly downregulated dependent on time duration (P < 0.01). Overall, the data indicate the antithetical regulation of Ihh versus has-miR-195-5p and has-miR-15b-5p during the differentiation process. These results support the hypothesis that these mi-RNAs could target the Ihh in the pathway of osteoblast differentiation derived from human ASCs.

Effect of conditioned media on the angiogenic activity of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are promising candidates for use in novel cell therapies, although such live cell products are highly complex compared with traditional drugs. For example, difficulties such as the control of manufacturing conditions hinder the manufacture of stable cell populations that maintain their therapeutic potency. Here, assuming that medium selection significantly affects cell potency, we focused on the culture media as a critical manufacturing factor influencing the therapeutic efficacy of MSCs. We therefore performed a tube formation assay to quantify the angiogenic activities of conditioned media used to culture human umbilical vein endothelial cells compared with unconditioned media. Comprehensive molecular genetic analysis using microarrays was applied to determine the effects of these media on signal transduction pathways. We found that activation of the vascular endothelial growth factor (VEGF) signaling pathway differed, and that VEGF concentration was dependent on the composition of the conditioned media. These results indicate that the activation level of cell signaling pathways which contribute to therapeutic efficacy may vary depending on the media components affecting MSCs during their cultivation. Moreover, they indicate that therapeutic efficacy will likely depend on how cells are handled during manufacture. These findings will enhance our understanding of the quality control measures required to ensure the efficacy and safety of cell therapy products.

Adipose Tissue-Derived Mesenchymal Stromal Cells Modulate Inflammatory Response and Improve Allograft Islet Transplant in Mice Model of Type 1 Diabetes

OBJECTIVE

Type 1 diabetes mellitus (T1DM) is an autoimmune disease where immune cells attack insulin-producing beta cells. Islet transplantation is a promising treatment for T1DM. This study aims to evaluate the effects of adipose tissue-derived mesenchymal stem cells (AT-MSCs) in combination with pancreatic islet transplantation using hydrogel.

METHODS

T1DM mouse model was established using streptozotocin (STZ). Islets and AT-MSCs were co-embedded in a hydrogel and transplanted into diabetic mice. Five groups with six animals in each (control, hydrogel alone, AT-MSCs embedded hydrogel, islet embedded in hydrogel, and islet + AT-MSCs co-imbedded into a hydrogel) were evaluated in terms of blood glucose, insulin levels and serum and lavage cytokine production.

RESULTS

During 32 days, blood glucose levels decreased from over 400 mg/dl to less than 150 mg/dl in the transplanted mice. Analysis showed increased transformation growth factor beta (TGF-β1) and IL-4 levels, while IL-17 and IFN-γ levels significantly decreased in the MSC-treated groups.

CONCLUSION

These findings suggest that using AT-MSCs with hydrogel could be a beneficial alternative for enhancing pancreatic islet engraftment and function.

Sustainable biofabrication: from bioprinting to AI-driven predictive methods

Biofabrication is potentially an inherently sustainable manufacturing process of bio-hybrid systems based on biomaterials embedded with cell communities. These bio-hybrids promise to augment the sustainability of various human activities, ranging from tissue engineering and robotics to civil engineering and ecology. However, as routine biofabrication practices are laborious and energetically disadvantageous, our society must refine production and validation processes in biomanufacturing. This opinion highlights the research trends in sustainable material selection and biofabrication techniques. By modeling complex biosystems, the computational prediction will allow biofabrication to shift from an error-trial method to an efficient, target-optimized approach with minimized resource and energy consumption. We envision that implementing bionomic rationality in biofabrication will render bio-hybrid products fruitful for greening human activities.

IL-10 Enhances the Inhibitory Effect of Adipose-Derived Stromal Cells on Insulin Resistance/Liver Gluconeogenesis by Treg Cell Induction

The modulation of cellular phenotypes within adipose tissue provides a potential means for therapeutic intervention for diabetes. Endogenous interleukin-10 (IL-10) protects against diet-induced insulin resistance. We examined the effects and mechanisms of action of IL-10-treated adipose-derived stromal cells on diabetes-induced insulin resistance and liver gluconeogenesis. We harvested stromal vascular fractions (SVFs) from the adipose tissue of diabetic (Leprdb/db) mice and treated them with IL-10 in vitro. SVFs treated with 10 or 100 ng of IL-10 were injected into the inguinal adipose tissue of Leprdb/db mice. IL-10 treatment suppressed the mRNA expression of IL-6, IL-33, CCL2, TNF-α, and IL-1β. Additionally, it suppressed the protein expression of IL-6, pmTOR, pJNK, and pNF-κB but enhanced Foxp3 mRNA expression in SVFs from diabetic mice. Meanwhile, IL-10 treatment repressed CCL2 and PDGFRα expression in adipose tissue macrophages (ATMs) and IL-6 expression in non-ATMs but increased the Foxp3 and IL-10 mRNA expression of ATMs from diabetic mice. Injection of IL-10-treated SVFs decreased the IL-6, IL-33, CCL2, IL-1β, and CCL2 but enhanced the Foxp3 and IL-10 mRNA expression of adipose tissue from Leprdb/db mice. Furthermore, injection of IL-10-treated SVFs increased CD4+ regulatory T cells (Tregs) in SVFs and adipose IL-10 levels and suppressed plasma adiponectin levels and DPP4 activity in diabetic mice. Injection of IL-10-treated SVFs decreased hepatic G6PC and PCK1 mRNA expression and increased Akt activation, STAT3 phosphorylation in the liver, and glucose tolerance in diabetic mice. Our data suggest that IL-10 treatment decreases inflammation in adipose SVFs of diabetic mice. Injection of IL-10-treated SVFs into the adipose tissue decreased diabetes-induced gluconeogenesis gene expression, DPP4 activity, and insulin resistance by enhancing Treg cells in diabetic mice. These data suggest that IL-10-treated adipose stromal vascular cells could be a promising therapeutic strategy for diabetes mellitus.

Aspirin Stimulates the Osteogenic Differentiation of Human Adipose Tissue-Derived Stem Cells In Vitro

This study investigates the impact of acetylsalicylic acid (ASA), also known as aspirin, on adipose tissue-derived stem cells (ASCs), aiming to elucidate its dose-dependent effects on morphology, viability, proliferation, and osteogenic differentiation. Isolated and characterized human ASCs were exposed to 0 µM, 100 µM, 200 µM, 400 µM, 800 µM, 1000 µM, 10,000 µM, and 16,000 µM of ASA in vitro. Cell morphology, viability, and proliferation were evaluated with fluorescent live/dead staining, alamarBlue viability reagent, and CyQUANT® cell proliferation assay, respectively. Osteogenic differentiation under stimulation with 400 µM or 1000 µM of ASA was assessed with alizarin red staining and qPCR of selected osteogenic differentiation markers (RUNX2, SPP1, ALPL, BGLAP) over a 3- and 21-day-period. ASA doses ≤ 1000 µM showed no significant impact on cell viability and proliferation. Live/dead staining revealed a visible reduction in viable cell confluency for ASA concentrations ≥ 1000 µM. Doses of 10,000 µM and 16,000 µM of ASA exhibited a strong cytotoxic and anti-proliferative effect in ASCs. Alizarin red staining revealed enhanced calcium accretion under the influence of ASA, which was macro- and microscopically visible and significant for 1000 µM of ASA (p = 0.0092) in quantification if compared to osteogenic differentiation without ASA addition over a 21-day-period. This enhancement correlated with a more pronounced upregulation of osteogenic markers under ASA exposure (ns). Our results indicate a stimulatory effect of 1000 µM of ASA on the osteogenic differentiation of ASCs. Further research is needed to elucidate the precise molecular mechanisms underlying this effect; however, this discovery suggests promising opportunities for enhancing bone tissue engineering with ASCs as cell source.

Adipose Tissue Derivatives in Peripheral Nerve Regeneration after Transection: A Systematic Review

INTRODUCTION

Peripheral nerve injury (PNI) is increasingly prevalent and challenging to treat despite advances in microsurgical techniques. In this context, adipose tissue derivatives, such as adipose-derived stem cells, nanofat, and stromal vascular fraction have been gaining attention as potential allies in peripheral nerve regeneration.

OBJECTIVES

This study aims to explore the use of adipose tissue derivatives in nerve regeneration following peripheral nerve transection in murine models. Thus, we assess and synthesize the key techniques and methods used for evaluating the obtained nerve regeneration to guide future experimental research and clinical interventions.

METHODOLOGY

A systematic review was conducted in February 2024, adhering to the Cochrane and PRISMA 2020 guidelines, using the PubMed, SciELO, and LILACS databases. The focus was on experimental studies involving adipose tissue derivatives in nerve regeneration in animal models post-transection. Only experimental trials reporting nerve regeneration outcomes were included; studies lacking a comparator group or evaluation methods were excluded.

RESULTS

Out of 273 studies initially identified from MEDLINE, 19 were selected for detailed analysis. The average study included 32.5 subjects, with about 10.2 subjects per intervention subgroup. The predominant model was the sciatic nerve injury with a 10 mm gap. The most common intervention involved unprocessed adipose-derived stem cells, utilized in 14 articles.

CONCLUSIONS

This review underscores the significant potential of current methodologies in peripheral nerve regeneration, particularly highlighting the use of murine models and thorough evaluation techniques.

Effect of ASC Injection in the Inflammatory Reaction in Silicone Implant Capsule: Animal Model

Background

Capsular contracture is a common complication affecting about 80% of patients who receive radiotherapy after breast reconstruction with silicone prostheses. This study examines the use of adipocyte stem cells (ASCs) to treat capsular contracture.

Methods

Thirty rats were operated on to implant a minisilicone prosthesis in the dorsal region. The rats were divided into three groups: control (saline solution injection), radiotherapy (RDT), and RDT + ASC. After 3 months, the capsules were collected and submitted to histological analysis for inflammatory cell presence, vascular density, and collagen fibers, and gene expression of Tnf, Il1rap, Il10, Cd68, Mmp3, and Mmp9 by qPCR.

Results

In macroscopic analysis, the RTGO score showed a two-point reduction in RDT + ASC compared with the RDT (P = 0.003). In histological analysis, ASC exhibited less than 50% of inflammatory cells compared with RDT (P = 0.004), which was similar to control. This study demonstrated that Il1rap gene expression was identical in both RDT and RTD + ASC. Compared with control, treatment with ASC reduced Il1rap expression by 30%. Cd68 and Mmp3 expression levels were similar in both the control and RTD + ASC.

Conclusion

This study suggests that ASC treatment decreases silicone prosthesis capsule inflammation.

Adipose Tissue Dysfunction and the Role of Adipocyte-Derived Extracellular Vesicles in Obesity and Metabolic Syndrome

Obesity is a major public health issue that is associated with metabolic diseases including diabetes mellitus type 2 and metabolic syndrome. This pathology leads to detrimental cardiovascular health and secondary effects, such as lipotoxicity, inflammation, and oxidative stress. Recently, extracellular vesicles (EVs) have been highlighted as novel players participating in human physiology and pathophysiology. In obesity, adipose tissue is related to the active shedding of adipocyte-derived extracellular vesicles (AdEVs). The current review explores and highlights the role of AdEVs and their cargo in obesity and metabolic syndrome. AdEVs are proposed to play an important role in obesity and its comorbidities. AdEVs are biological nanoparticles mainly shed by visceral and subcutaneous adipose tissue, acting in physiological and pathophysiological conditions, and also carrying different cargo biomolecules, such as RNA, microRNA (miRNA), proteins, and lipids, among others. RNA and miRNA have local and systemic effects affecting gene expression in target cell types via paracrine and endocrine actions. State of the art analyses identified some miRNAs, such as miR-222, miR-23b, miR-4429, miR-148b, and miR-4269, that could potentially affect cell pathways involved in obesity-related comorbidities, such as chronic inflammation and fibrosis. Similarly, AdEVs-proteins (RBP4, perilipin-A, FABP, mimecan, TGFBI) and AdEVs-lipids (sphingolipids) have been linked to the obesity pathophysiology. The current knowledge about AdEVs along with further research would support and reveal novel pathways, potential biomarkers, and therapeutic options in obesity.

Adipose-derived mesenchymal stem cells' adipogenesis chemistry analyzed by FTIR and Raman metrics

The full understanding of molecular mechanisms of cell differentiation requires a holistic view. Here we combine label-free FTIR and Raman hyperspectral imaging with data mining to detect the molecular cell composition enabling noninvasive monitoring of cell differentiation and identifying biochemical heterogeneity. Mouse adipose-derived mesenchymal stem cells (AD-MSCs) undergoing adipogenesis were followed by Raman and FT-IR imaging, Oil Red, and immunofluorescence. A workflow of the data analysis (IRRSmetrics4stem) was designed to identify spectral predictors of adipogenesis and test machine-learning (ML) methods (hierarchical clustering, PCA, PLSR) for the control of the AD-MSCs differentiation degree. IRRSmetrics4stem provided insights into the chemism of adipogenesis. With single-cell tracking, we established IRRS metrics for lipids, proteins, and DNA variations during AD-MSCs differentiation. The over 90% predictive efficiency of the selected ML methods proved the high sensitivity of the IRRS metrics. Importantly, the IRRS metrics unequivocally recognize a switch from proliferation to differentiation. This study introduced a new bioassay identifying molecular markers indicating molecular transformations and delivering rapid and machine learning-based monitoring of adipogenesis that can be relevant to other differentiation processes. Thus, we introduce a novel, rapid, machine learning-based bioassay to identify molecular markers of adipogenesis. It can be relevant to identification of differentiation-related molecular processes in other cell types, and beyond the cell differentiation including progression of different cellular pathophysiologies reconstituted in vitro.

Circulating plasma fibronectin affects tissue insulin sensitivity, adipocyte differentiation, and transcriptional landscape of adipose tissue in mice

Plasma fibronectin (pFN) is a hepatocyte-derived circulating extracellular matrix protein that affects cell morphology, adipogenesis, and insulin signaling of adipocytes in vitro. In this study, we show pFN accrual to adipose tissue and its contribution to tissue homeostasis in mice. Hepatocyte-specific conditional Fn1 knockout mice (Fn1-/-ALB) show a decrease in adipose tissue FN levels and enhanced insulin sensitivity of subcutaneous (inguinal), visceral (epididymal) adipose tissue on a normal diet. Diet-induced obesity model of the Fn1-/-ALB mouse showed normal weight gain and whole-body fat mass, and normal adipose tissue depot volumes and unaltered circulating leptin and adiponectin levels. However, Fn1-/-ALB adipose depots showed significant alterations in adipocyte size and gene expression profiles. The inguinal adipose tissue on a normal diet, which had alterations in fatty acid metabolism and thermogenesis suggesting browning. The presence of increased beige adipocyte markers Ucp1 and Prdm16 supported this. In the inguinal fat, the obesogenic diet resulted in downregulation of the browning markers and changes in gene expression reflecting development, morphogenesis, and mesenchymal stem cell maintenance. Epididymal adipose tissue showed alterations in developmental and stem cell gene expression on both diets. The data suggests a role for pFN in adipose tissue insulin sensitivity and cell profiles.

Surgical Management of Chronic Neuropathic Burn Pain

Burn-related chronic neuropathic pain can contribute to a decreased quality of life. When medical and pharmacologic therapies prove ineffective, patients should undergo evaluation for surgical intervention, consisting of a detailed physical examination and elective diagnostic nerve block, to identify an anatomic cause of pain. Based on symptoms and physical examination findings, particularly Tinel's sign, treatments can vary, including a trial of laser therapies, fat grafting, or nerve surgeries (nerve decompression, neuroma excision, targeted muscle reinnervation, regenerative peripheral nerve interfaces, and vascularized denervated muscle targets). It is essential to counsel patients to establish appropriate expectations prior to treatment with a multidisciplinary team.

Expert Consensus on the Application of Stem Cells in Psoriasis Research and Clinical Trials

Psoriasis is an immune-mediated, chronic, relapsing, inflammatory, systemic disease induced by individual-environmental interactions, and is often lifelong because of the difficulty of treatment. In recent years, a variety of targeted therapies, including biologics, have improved the lesions and quality of life of most psoriasis patients, but they still do not address the problem of relapse and may be associated with decreased efficacy or adverse events such as infections over time. Therefore, there is an urgent need for breakthroughs in psoriasis treatment and in relapse-delaying and non-pharmacologic strategies, and stem cell therapy for psoriasis has emerged. In recent years, research on stem cell therapy for psoriasis has received a lot of attention, however, there is no reference standard as well as consensus in this field of research. Therefore, according to the latest consensus and guidelines, combined with relevant literature reports, clinical practice experience and the results of discussions with experts, this consensus specifies the types of stem cells commonly used in the treatment of psoriasis, the methods, dosages, and routes of stem cell therapy for psoriasis, as well as the clinical evaluations (efficacy and safety) of stem cell therapy for psoriasis. In addition, this consensus also provides normative standards for the processes of collection, preparation, preservation and quality control of stem cells and their related products, as well as recommendations for the management of stem cells during infusion for the treatment of psoriasis. This consensus provides the latest specific reference standards and practice guidelines for the field of stem cell therapy for psoriasis.

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.

Non-enzymatic methods for isolation of stromal vascular fraction and adipose-derived stem cells: A systematic review

BACKGROUND

Adipose-derived stem cells (ADSCs) and the stromal vascular fraction (SVF) have garnered substantial interest in regenerative medicine due to their potential to treat a wide range of conditions. Traditional enzymatic methods for isolating these cells face challenges such as high costs, lengthy processing time, and regu-latory complexities.

AIM

This systematic review aimed to assess the efficacy and practicality of non-enzymatic, mechanical methods for isolating SVF and ADSCs, comparing these to conventional enzymatic approaches.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a comprehensive literature search was conducted across multiple databases. Studies were selected based on inclusion criteria focused on non-enzymatic isolation methods for SVF and ADSCs from adipose tissue. The risk of bias was assessed, and a qualitative synthesis of findings was performed due to the methodological heterogeneity of the included studies.

RESULTS

Nineteen studies met the inclusion criteria, highlighting various mechanical techniques such as centrifugation, vortexing, and ultrasonic cavitation. The review identified significant variability in cell yield and viability, and the integrity of isolated cells across different non-enzymatic methods compared to enzymatic procedures. Despite some advantages of mechanical methods, including reduced processing time and avoidance of enzymatic reagents, the evidence suggests a need for optimization to match the cell quality and therapeutic efficacy achievable with enzymatic isolation.

CONCLUSION

Non-enzymatic, mechanical methods offer a promising alternative to enzymatic isolation of SVF and ADSCs, potentially simplifying the isolation process and reducing regulatory hurdles. However, further research is necessary to standardize these techniques and ensure consistent, high-quality cell yields for clinical applications. The development of efficient, safe, and reproducible non-enzymatic isolation methods could significantly advance the field of regenerative medicine.

Donor Sites and Harvesting Techniques Affect miRNA Cargos of Extracellular Vesicles Released by Human Adipose-Derived Mesenchymal Stromal Cells

Osteoarthritis (OA) is a degenerative joint disorder characterized by the progressive deterioration of articular cartilage driven and sustained by catabolic and inflammatory processes that lead to pain and functional impairment. Adipose-derived stem cells (ASCs) have emerged as a promising therapeutic strategy for OA due to their regenerative potential, which mainly relies on the adaptive release of paracrine molecules that are soluble or encapsulated in extracellular vesicles (EVs). The biological effects of EVs specifically depend on their cargo; in particular, microRNAs (miRNAs) can specifically modulate target cell function through gene expression regulation. This study aimed to investigate the impact of collection site (abdominal vs. peri-trochanteric adipose tissue) and collection method (surgical excision vs. lipoaspiration) on the miRNAs profile in ASC-derived EVs and their potential implications for OA therapy. EV-miRNA cargo profiles from ASCs of different origins were compared. An extensive bioinformatics search through experimentally validated and OA-related targets, pathways, and tissues was conducted. Several miRNAs involved in the restoration of cartilage homeostasis and in immunomodulation were identified in all ASC types. However, EV-miRNA expression profiles were affected by both the tissue-harvesting site and procedure, leading to peculiar characteristics for each type. Our results suggest that adipose-tissue-harvesting techniques and the anatomical site of origin influence the therapeutic efficacy of ASC-EVs for tissue-specific regenerative therapies in OA, which warrants further investigation.

De novo regeneration of dentin pulp complex mediated by Adipose derived stem cells in an immunodeficient albino rat model (Histological, histochemical and scanning electron microscopic Study)

Background

Dental tissue engineering is an alternative procedure for restoring damaged dental tissues. Adipose-derived stem cells are a new source of cells for regenerative endodontics in combination with scaffold materials. The descriptive data about this regenerative process is still insufficient.

Objective

To evaluate the regenerative potential of Adipose-derived stem cells using a self-assembling polypeptide scaffold for the dentin-pulp complex in an emptied root canal space.

Material and Methods

40 root segments of human single-rooted teeth were transplanted into the albino rats' dorsal subcutaneous tissue. Root segments were divided into two groups: group I contained only a self-assembling polypeptide scaffold, and group II contained fluorescent-labeled Adipose-derived stem cells embedded in a self-assembling polypeptide scaffold. The newly formed tissues were assessed on the 60th and 90th days post-transplantation using routine histological examination, Masson trichrome staining, and scanning electron microscopy.

Results

Group I showed granulation tissue without any signs of predentin formation or odontoblast-like cells. Group II revealed the presence of predentin tissue along the dentin margin, with arranged odontoblast-like cells. An organized connective tissue with abundant vasculature and calcific masses was observed in the pulp space.

Conclusion

Adipose-derived stem cells can be considered as alternative stem cells for regenerating the dentin-pulp complex. Dentin pulp complex regeneration utilizing a self-assembling polypeptide scaffold alone would not yield successful results.

NPTX1 Mediates the Facilitating Effects of Hypoxia-Stimulated Human Adipocytes on Adipose-Derived Stem Cell Activation and Autologous Adipose Graft Survival Rate

BACKGROUND

Autologous adipose tissue is an ideal material for soft tissue filling and transplantation; however, high volumes of fat absorption over time lead to a relatively low overall survival percentage. The survival and differentiation of adipose-derived stem cells (ADSCs) in the transplanted microenvironment might improve adipose graft survival. Adipocytes have been reported to affect ADSC activation. However, its underlying mechanisms remain unclear.

METHODS

Human ADSCs were incubated in a culture medium supplemented with hypoxic or normoxic conditioned culture medium (CM) derived from human adipocytes. Neuronal Pentraxin 1 (NPTX1) was overexpressed or knocked down in human adipocytes using an overexpression vector (NPTX1 OE) or small interfering RNA (siRNA) transfection, respectively. ADSC differentiation and paracrine secretion were assessed. Nude mice were implanted with human adipocytes and ADSCs. The adipose tissue was subsequently evaluated by histological analysis.

RESULTS

CM from hypoxic-stimulated human adipocytes significantly facilitated the differentiation ability and paracrine levels of ADSCs. NPTX1 was significantly up-regulated in human adipocytes exposed to hypoxic conditions. In vitro, CM derived from hypoxia-stimulated human adipocytes or NPTX1-overexpressing human adipocytes exposed to normoxia promoted ADSC differentiation and paracrine; after silencing NPTX1, the facilitating effects of hypoxia-treated human adipocytes on ADSC activation were eliminated. Similarly, in vivo, the NPTX1 OE + normoxia-CM group saw improved histological morphology and fat integrity, less fibrosis and inflammation, and increased vessel numbers compared with the OE NC + normoxia-CM group; the adipocyte grafts of the si-NC + hypoxia-CM group yielded the most improved histological morphology, fat integrity, and the most vessel numbers. However, these enhancements of ADSC activation and adipose graft survival were partially abolished by NPTX1 knockdown in human adipocytes.

CONCLUSION

NPTX1 might mediate the facilitating effects of hypoxia-stimulated human adipocytes on ADSC activation, thereby improving adipose tissue survival rate after autologous fat transplantation and the effectiveness of autologous fat transplantation through promoting ADSC activation.

LEVEL OF EVIDENCE III

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 .

The tardigrade-derived mitochondrial abundant heat soluble protein improves adipose-derived stem cell survival against representative stressors

Human adipose-derived stem cell (ASC) grafts have emerged as a powerful tool in regenerative medicine. However, ASC therapeutic potential is hindered by stressors throughout their use. Here we demonstrate the transgenic expression of the tardigrade-derived mitochondrial abundant heat soluble (MAHS) protein for improved ASC resistance to metabolic, mitochondrial, and injection shear stress. In vitro, MAHS-expressing ASCs demonstrate up to 61% increased cell survival following 72 h of incubation in phosphate buffered saline containing 20% media. Following up to 3.5% DMSO exposure for up to 72 h, a 14-49% increase in MAHS-expressing ASC survival was observed. Further, MAHS expression in ASCs is associated with up to 39% improved cell viability following injection through clinically relevant 27-, 32-, and 34-gauge needles. Our results reveal that MAHS expression in ASCs supports survival in response to a variety of common stressors associated with regenerative therapies, thereby motivating further investigation into MAHS as an agent for stem cell stress resistance. However, differentiation capacity in MAHS-expressing ASCs appears to be skewed in favor of osteogenesis over adipogenesis. Specifically, activity of the early bone formation marker alkaline phosphatase is increased by 74% in MAHS-expressing ASCs following 14 days in osteogenic media. Conversely, positive area of the neutral lipid droplet marker BODIPY is decreased by up to 10% in MAHS-transgenic ASCs following 14 days in adipogenic media. Interestingly, media supplementation with up to 40 mM glucose is sufficient to restore adipogenic differentiation within 14 days, prompting further analysis of mechanisms underlying interference between MAHS and differentiation processes.

Efficacy of stromal vascular fraction for knee osteoarthritis: A prospective, single-centre, non-randomized study with 2 years follow-up

BACKGROUND

Current osteoarthritis (OA) treatments focus on symptom relief without addressing the underlying disease process. In regenerative medicine, current treatments have limitations. In regenerative medicine, more research is needed for intra-articular stromal vascular fraction (SVF) injections in OA, including dosage optimization, long-term efficacy, safety, comparisons with other treatments, and mechanism exploration.

AIM

To compare the efficacy of intra-articular SVF with corticosteroid (ICS) injections in patients with primary knee OA.

METHODS

The study included 50 patients with Kellgren-Lawrence grades II and III OA. Patients were randomly assigned (1:1) to receive either a single intra-articular SVF injection (group A) or a single intra-articular ICS (triamcinolone) (group B) injection. Patients were followed up at 1, 3, 6, 12, and 24 months. Visual analog score (VAS) and International Knee Documentation Committee (IKDC) scores were administered before the procedure and at all follow-ups. The safety of SVF in terms of adverse and severe adverse events was recorded. Statistical analysis was performed with SPSS Version 26.0, IBM Corp, Chicago, IL, United States.

RESULTS

Both groups had similar demographics and baseline clinical characteristics. Follow-up showed minor patient loss, resulting in 23 and 24 in groups A and B respectively. Group A experienced a notable reduction in pain, with VAS scores decreasing from 7.7 to 2.4 over 24 months, compared to a minor reduction from 7.8 to 6.2 in Group B. This difference in pain reduction in group A was statistically significant from the third month onwards. Additionally, Group A showed significant improvements in knee functionality, with IKDC scores rising from 33.4 to 83.10, whereas Group B saw a modest increase from 36.7 to 45.16. The improvement in Group A was statistically significant from 6 months and maintained through 24 months.

CONCLUSION

Our study demonstrated that intra-articular administration of SVF can lead to reduced pain and improved knee function in patients with primary knee OA. More adequately powered, multi-center, double-blinded, randomised clinical trials with longer follow-ups are needed to further establish safety and justify its clinical use.

Biomimetic gradient scaffolds for the tissue engineering and regeneration of rotator cuff enthesis

Rotator cuff tear is one of the most common musculoskeletal disorders, which often results in recurrent shoulder pain and limited movement. Enthesis is a structurally complex and functionally critical interface connecting tendon and bone that plays an essential role in maintaining integrity of the shoulder joint. Despite the availability of advanced surgical procedures for rotator cuff repair, there is a high rate of failure following surgery due to suboptimal enthesis healing and regeneration. Novel strategies based on tissue engineering are gaining popularity in improving tendon-bone interface (TBI) regeneration. Through incorporating physical and biochemical cues into scaffold design which mimics the structure and composition of native enthesis is advantageous to guide specific differentiation of seeding cells and facilitate the formation of functional tissues. In this review, we summarize the current state of research in enthesis tissue engineering highlighting the development and application of biomimetic scaffolds that replicate the gradient TBI. We also discuss the latest techniques for fabricating potential translatable scaffolds such as 3D bioprinting and microfluidic device. While preclinical studies have demonstrated encouraging results of biomimetic gradient scaffolds, the translation of these findings into clinical applications necessitates a comprehensive understanding of their safety and long-term efficacy.

Insights into the role of adipose-derived stem cells and secretome: potential biology and clinical applications in hypertrophic scarring

Scar tissue is the inevitable result of repairing human skin after it has been subjected to external destructive stimuli. It leads to localized damage to the appearance of the skin, accompanied by symptoms such as itching and pain, which reduces the quality of life of the patient and causes serious medical burdens. With the continuous development of economy and society, there is an increasing demand for beauty. People are looking forward to a safer and more effective method to eliminate pathological scarring. In recent years, adipose-derived stem cells (ADSCs) have received increasing attention from researchers. It can effectively improve pathological scarring by mediating inflammation, regulating fibroblast proliferation and activation, and vascular reconstruction. This review focuses on the pathophysiological mechanisms of hypertrophic scarring, summarizing the therapeutic effects of in vitro, in vivo, and clinical studies on the therapeutic effects of ADSCs in the field of hypertrophic scarring prevention and treatment, the latest application techniques, such as cell-free therapies utilizing ADSCs, and discussing the advantages and limitations of ADSCs. Through this review, we hope to further understand the characterization of ADSC and clarify the effectiveness of its application in hypertrophic scarring treatment, so as to provide clinical guidance.

Single-cell RNA sequencing reveals the heterogeneity of adipose tissue-derived mesenchymal stem cells under chondrogenic induction

This study investigated how adipose tissue-derived mesenchymal stem cells (AT-MSCs) respond to chondrogenic induction using droplet-based single-cell RNA sequencing (scRNA-seq). We analyzed 37,219 high-quality transcripts from control cells and cells induced for 1 week (1W) and 2 weeks (2W). Four distinct cell clusters (0-3), undetectable by bulk analysis, exhibited varying proportions. Cluster 1 dominated in control and 1W cells, whereas clusters (3, 2, and 0) exclusively dominated in control, 1W, and 2W cells, respectively. Furthermore, heterogeneous chondrogenic markers expression within clusters emerged. Gene ontology (GO) enrichment analysis of differentially expressed genes unveiled cluster-specific variations in key biological processes (BP): (1) Cluster 1 exhibited up-regulation of GO-BP terms related to ribosome biogenesis and translational control, crucial for maintaining stem cell properties and homeostasis; (2) Additionally, cluster 1 showed up-regulation of GO-BP terms associated with mitochondrial oxidative metabolism; (3) Cluster 3 displayed up-regulation of GO-BP terms related to cell proliferation; (4) Clusters 0 and 2 demonstrated similar up-regulation of GO-BP terms linked to collagen fibril organization and supramolecular fiber organization. However, only cluster 0 showed a significant decrease in GO-BP terms related to ribosome production, implying a potential correlation between ribosome regulation and the differentiation stages of AT-MSCs. Overall, our findings highlight heterogeneous cell clusters with varying balances between proliferation and differentiation before, and after, chondrogenic stimulation. This provides enhanced insights into the single-cell dynamics of AT-MSCs during chondrogenic differentiation. [BMB Reports 2024; 57(5): 232-237].

Cornea-Specific Human Adipose Stem Cell-Derived Extracellular Matrix for Corneal Stroma Tissue Engineering

Utilizing tissue-specific extracellular matrices (ECMs) is vital for replicating the composition of native tissues and developing biologically relevant biomaterials. Human- or animal-derived donor tissues and organs are the current gold standard for the source of these ECMs. To overcome the several limitations related to these ECM sources, including the highly limited availability of donor tissues, cell-derived ECM offers an alternative approach for engineering tissue-specific biomaterials, such as bioinks for three-dimensional (3D) bioprinting. 3D bioprinting is a state-of-the-art biofabrication technology that addresses the global need for donor tissues and organs. In fact, there is a vast global demand for human donor corneas that are used for treating corneal blindness, often resulting from damage in the corneal stromal microstructure. Human adipose tissue is one of the most abundant tissues and easy to access, and adipose tissue-derived stem cells (hASCs) are a highly advantageous cell type for tissue engineering. Furthermore, hASCs have already been studied in clinical trials for treating corneal stromal pathologies. In this study, a corneal stroma-specific ECM was engineered without the need for donor corneas by differentiating hASCs toward corneal stromal keratocytes (hASC-CSKs). Furthermore, this ECM was utilized as a component for corneal stroma-specific bioink where hASC-CSKs were printed to produce corneal stroma structures. This cost-effective approach combined with a clinically relevant cell type provides valuable information on developing more sustainable tissue-specific solutions and advances the field of corneal tissue engineering.

Development of a Composite Hydrogel Containing Statistically Optimized PDGF-Loaded Polymeric Nanospheres for Skin Regeneration: In Vitro Evaluation and Stem Cell Differentiation Studies

Platelet-derived growth factor-BB (PDGF-BB) is a polypeptide growth factor generated by platelet granules faced to cytokines. It plays a role in forming and remodeling various tissue types, including epithelial tissue, through interaction with cell-surface receptors on most mesenchymal origin cells. However, it breaks down quickly in biological fluids, emphasizing the importance of preserving them from biodegradation. To address this challenge, we formulated and evaluated PDGF-encapsulated nanospheres (PD@PCEC) using polycaprolactone-polyethylene glycol-polycaprolactone. PD@PCECs were fabricated through the triple emulsion methodology and optimized by using the Box-Behnken design. The encapsulation efficiency (EE) of nanoencapsulated PDGF-BB was investigated concerning four variables: stirring rate (X1), stirring duration (X2), poly(vinyl alcohol) concentration (X3), and PDGF-BB concentration (X4). The selected optimized nanospheres were integrated into a gelatin-collagen scaffold (PD@PCEC@GC) and assessed for morphology, biocompatibility, in vitro release, and differentiation-inducing activity in human adipose-derived stem cells (hADSCs). The optimized PD@PCEC nanospheres exhibited a particle size of 177.9 ± 91 nm, a zeta potential of 5.2 mV, and an EE of 87.7 ± 0.44%. The release profile demonstrated approximately 85% of loaded PDGF-BB released during the first 360 h, with a sustained release over the entire 504 h period, maintaining bioactivity of 87.3%. The study also included an evaluation of the physicochemical properties of the scaffolds and an assessment of hADSC adhesion to the scaffold's surface. Additionally, hADSCs cultivated within the scaffold effectively differentiated into keratinocyte-like cells (KLCs) over 21 days, evidenced by morphological changes and upregulation of keratinocyte-specific genes, including cytokeratin 18, cytokeratin 19, and involucrin, at both transcriptional and protein levels.

Ushering in the era of regenerative surgery

Tissue loss, irrespective of etiology, often requires extensive reconstruction. In many instances, the need exceeds what current treatments and technologies modern medicine can offer. Tissue engineering has made immense strides within the past few decades due to advances in biologics, biomaterials, and manufacturing. The convergence of these three domains has created limitless potential for future surgical care. Unfortunately, there still exists a disconnect on how to best implant these 'replacement parts' and care for the patient. It is therefore vital to develop paradigms for the integration of advanced surgical and tissue engineering technologies. This paper explores the convergence between tissue engineering and reconstructive surgery. We will describe the clinical problem of tissue loss, discuss currently available solutions, address limitations, and propose processes for integrating surgery and tissue engineering, thereby ushering in the era of regenerative surgery.

Adipose tissue-derived stem cells, in vivo and in vitro models for metabolic diseases

The primary role of adipose tissue stem cells (ADSCs) is to support the function and homeostasis of adipose tissue in physiological and pathophysiological conditions. However, when ADSCs become dysfunctional in diseases such as obesity and cancer, they become impaired, undergo signalling changes, and their epigenome is altered, which can have a dramatic effect on human health. In more recent years, the therapeutic potential of ADSCs in regenerative medicine, wound healing, and for treating conditions such as cancer and metabolic diseases has been extensively investigated with very promising results. ADSCs have also been used to generate two-dimensional (2D) and three-dimensional (3D) cellular and in vivo models to study adipose tissue biology and function as well as intracellular communication. Characterising the biology and function of ADSCs, how it is altered in health and disease, and its therapeutic potential and uses in cellular models is key for designing intervention strategies for complex metabolic diseases and cancer.

Characterization of 3D Organotypic Culture of Mouse Adipose-Derived Stem Cells

Although stem cells are a promising avenue for harnessing the potential of adipose tissue, conventional two-dimensional (2D) culture methods have limitations. This study explored the use of three-dimensional (3D) cultures to preserve the regenerative potential of adipose-derived stem cells (ADSCs) and investigated their cellular properties. Flow cytometric analysis revealed significant variations in surface marker expressions between the two culture conditions. While 2D cultures showed robust surface marker expressions, 3D cultures exhibited reduced levels of CD44, CD90.2, and CD105. Adipogenic differentiation in 3D organotypic ADSCs faced challenges, with decreased organoid size and limited activation of adipogenesis-related genes. Key adipocyte markers, such as lipoprotein lipase (LPL) and adipoQ, were undetectable in 3D-cultured ADSCs, unlike positive controls in 2D-cultured mesenchymal stem cells (MSCs). Surprisingly, 3D-cultured ADSCs underwent mesenchymal-epithelial transition (MET), evidenced by increased E-cadherin and EpCAM expression and decreased mesenchymal markers. This study highlights successful ADSC organoid formation, notable MSC phenotype changes in 3D culture, adipogenic differentiation challenges, and a distinctive shift toward an epithelial-like state. These findings offer insights into the potential applications of 3D-cultured ADSCs in regenerative medicine, emphasizing the need for further exploration of underlying molecular mechanisms.

Unlocking Potential: Low Bovine Serum Albumin Enhances the Chondrogenicity of Human Adipose-Derived Stromal Cells in Pellet Cultures

Bovine serum albumin (BSA) plays a crucial role in cell culture media, influencing cellular processes such as proliferation and differentiation. Although it is commonly included in chondrogenic differentiation media, its specific function remains unclear. This study explores the effect of different BSA concentrations on the chondrogenic differentiation of human adipose-derived stromal/stem cells (hASCs). hASC pellets from six donors were cultured under chondrogenic conditions with three BSA concentrations. Surprisingly, a lower BSA concentration led to enhanced chondrogenesis. The degree of this effect was donor-dependent, classifying them into two groups: (1) high responders, forming at least 35% larger, differentiated pellets with low BSA in comparison to high BSA; (2) low responders, which benefitted only slightly from low BSA doses with a decrease in pellet size and marginal differentiation, indicative of low intrinsic differentiation potential. In all cases, increased chondrogenesis was accompanied by hypertrophy under low BSA concentrations. To the best of our knowledge, this is the first study showing improved chondrogenicity and the tendency for hypertrophy with low BSA concentration compared to standard levels. Once the tendency for hypertrophy is understood, the determination of BSA concentration might be used to tune hASC chondrogenic or osteogenic differentiation.

In vitro aging alters the gene expression and secretome composition of canine adipose-derived mesenchymal stem cells

Introduction

Canine adipose-derived mesenchymal stem cells (cAD-MSCs) hold therapeutic promise due to their regenerative potential, particularly within their secretome. However, concerns arise regarding the impact of in vitro cultivation necessitated for storing therapeutic doses, prompting this study to comprehensively explore the impact of in vitro aging on gene expression and secretome composition.

Methods

The study involved collecting abdominal adipose tissue samples from nine healthy female dogs, from which cAD-MSCs were extracted and cultured. Stem cells were validated through trilineage differentiation assays and flow cytometry immunophenotyping. Gene expression profiling using RT-qPCR array, and cAD-MSCs secretome LC-MS/MS analysis, were conducted at passages 3 and 6 to reveal gene expression and protein composition alterations during in vitro culture.

Results and Discussion

The results demonstrate that the gene expression and secretome composition of cAD-MSCs were impacted by in vitro aging. Among many alterations in gene expression between two passages, two significant downregulations were noted in the MSC-associated PTPRC and IL10 genes. While the majority of proteins and their functional characteristics were shared between passages, the influence of cell aging on secretome composition is highlighted by 10% of proteins being distinctively expressed in each passage, along with 21 significant up- and downregulations. The functional attributes of proteins detected in passage 3 demonstrated a greater inclination towards supporting the regenerative capacity of cAD-MSCs. Moreover, proteins in passage 6 exhibited a noteworthy correlation with the blood coagulation pathway, suggesting an elevated likelihood of coagulation events. To the best of our knowledge, this study presents the first original perspective on the changes in secretome composition that occur when cAD-MSCs age in vitro. Furthermore, it contributes to broadening the currently restricted knowledge base concerning the secretome of cAD-MSCs. In conclusion, our findings show that the regenerative potential of cAD-MSCs, as well as their secretome, may be compromised by in vitro aging. Therefore, our study suggests a preference for earlier passages when considering these cells for therapeutic applications.

Differentiation of Adipose Tissue Mesenchymal Stem Cells into Endothelial Cells Depends on Fat Depot Conditions: Regulation by miRNA

The development of obesity is associated with substantial modulation of adipose tissue (AT) structure. The plasticity of the AT is reflected by its remarkable ability to expand or reduce in size throughout the adult lifespan, which is linked to the development of its vasculature. This increase in AT vasculature could be mediated by the differentiation of adipose tissue-derived stem cells (ASCs) into endothelial cells (ECs) and form new microvasculature. We have already shown that microRNA (miRNA)-145 regulates the differentiation of ASCs into EC-like (ECL) cells. Here, we investigated whether ASCs-differentiation into ECs is governed by a miRNAs signature that depends on fat depot location and /or the metabolic condition produced by obesity. Human ASCs, which were obtained from white AT by surgical procedures from lean and obese patients, were induced to differentiate into ECL cells. We have identified that miRNA-29b-3p in both subcutaneous (s)ASCs and visceral ASCs and miRNA-424-5p and miRNA-378a-3p in subcutaneous (s)ASCs are involved in differentiation into EC-like cells. These miRNAs modulate their pro-angiogenic effects on ASCs by targeting FGFR1, NRP2, MAPK1, and TGF-β2, and the MAPK signaling pathway. We show for the first time that miRNA-29b-3p upregulation contributes to ASCs' differentiation into ECL cells by directly targeting TGFB2 in both sASCs and visceral ASCs. Moreover, our results reveal that, independent of sASCs' origin (obese/lean), the upregulation of miRNA-378a-3p and the downregulation of miRNA-424-5p inhibit MAPK1 and overexpress FGFR1 and NRP2, respectively. In summary, both the adipose depot location and obesity affect the differentiation of resident ASCs through the expression of specific miRNAs.

The Efficacy of Stem Cells in Wound Healing: A Systematic Review

Wound healing is an intricate process involving coordinated interactions among inflammatory cells, skin fibroblasts, keratinocytes, and endothelial cells. Successful tissue repair hinges on controlled inflammation, angiogenesis, and remodeling facilitated by the exchange of cytokines and growth factors. Comorbid conditions can disrupt this process, leading to significant morbidity and mortality. Stem cell therapy has emerged as a promising strategy for enhancing wound healing, utilizing cells from diverse sources such as endothelial progenitor cells, bone marrow, adipose tissue, dermal, and inducible pluripotent stem cells. In this systematic review, we comprehensively investigated stem cell therapies in chronic wounds, summarizing the clinical, translational, and primary literature. A systematic search across PubMed, Embase, Web of Science, Google Scholar, and Cochrane Library yielded 22,454 articles, reduced to 44 studies after rigorous screening. Notably, adipose tissue-derived mesenchymal stem cells (AD-MSCs) emerged as an optimal choice due to their abundant supply, easy isolation, ex vivo proliferative capacities, and pro-angiogenic factor secretion. AD-MSCs have shown efficacy in various conditions, including peripheral arterial disease, diabetic wounds, hypertensive ulcers, bullous diabeticorum, venous ulcers, and post-Mohs micrographic surgery wounds. Delivery methods varied, encompassing topical application, scaffold incorporation, combination with plasma-rich proteins, and atelocollagen administration. Integration with local wound care practices resulted in reduced pain, shorter healing times, and improved cosmesis. Stem cell transplantation represents a potential therapeutic avenue, as transplanted stem cells not only differentiate into diverse skin cell types but also release essential cytokines and growth factors, fostering increased angiogenesis. This approach holds promise for intractable wounds, particularly chronic lower-leg wounds, and as a post-Mohs micrographic surgery intervention for healing defects through secondary intention. The potential reduction in healthcare costs and enhancement of patient quality of life further underscore the attractiveness of stem cell applications in wound care. This systematic review explores the clinical utilization of stem cells and stem cell products, providing valuable insights into their role as ancillary methods in treating chronic wounds.

Use of brown adipose tissue transplantation and engineering as a thermogenic therapy in obesity and metabolic disease

The induction of thermogenesis in brown adipose tissue is emerging as an attractive therapy for obesity and metabolic syndrome. However, the long-term efficacy and safety of clinical pharmaceutical agents have yet to be fully characterized. The transplantation of brown adipose tissue represents an alternative approach that might have a therapeutic effect by inducing a long-term increase in energy expenditure. However, limited tissue resources hinder the development of transplantation. Stem cell-based therapy and brown adipose tissue engineering, in addition to transplantation, represent alternative approaches that might resolve this problem. In this article, we discuss recent advances in understanding the mechanisms and applications of brown adipose tissue transplantation in the treatment of obesity and related metabolic disorders. Specifically, the induction of brown adipocytes and the fabrication of engineered brown adipose tissue as novel transplantation resources have long-term effects on ameliorating metabolic defects in rodent models. Additionally, we explore future prospects regarding the development of three-dimensional engineered brown adipose tissue and the associated challenges.

Isolation methods, proliferation, and adipogenic differentiation of adipose-derived stem cells from different fat depots in bovines

The adipose-derived stem cells (ASCs) are a valuable resource for regenerative medicine and essential materials for research in fat deposition. However, the isolation procedure of ASCs has not been standardized and needs to be harmonized; differences in proliferation and adipogenic differentiation of ASCs obtained from different fat depots have not been well characterized. In the present study, we compared the efficiency of ASCs isolation by enzymatic treatment and explant culture methods and the proliferation ability and adipogenic differentiation potential of ASCs isolated from subcutaneous and visceral fat depots. The explant culture method was simple and with no need for expensive enzymes while the enzymatic treatment method was complex, time consuming and costly. By the explant culture method, a larger number of ASCs were isolated from subcutaneous and visceral fat depots. By contrast, fewer ASCs were obtained by the enzymatic treatment method, especially from visceral adipose. ASCs isolated by the explant culture method performed well in cell proliferation and adipogenic differentiation, though they were slightly lower than those by the enzymatic treatment method. ASCs isolated from visceral depot demonstrated higher proliferation ability and adipogenic differentiation potential. In total, the explant culture method is simpler, more efficient, and lower cost than the enzymatic treatment method for ASCs isolation; compared with visceral adipose, subcutaneous adipose is easier to isolate ASCs; however, the visceral ASCs are superior to subcutaneous ASCs in proliferation and adipogenic differentiation.

Isolation and characterization of feline endometrial mesenchymal stem cells

BACKGROUND

Recently, there has been a growing interest in stem cells for human medicine. Limited feline endometrial mesenchymal stem cell (fEM-MSC) research in veterinary medicine necessitates reporting for future feline disease research and therapy.

OBJECTIVES

This study aimed to isolate fEM-MSCs from feline endometrial tissues and evaluate their morphology, proliferative ability, differentiation ability, and immunophenotype.

METHODS

Feline endometrial tissues were obtained from the ovariohysterectomies of healthy cats and isolated using an enzymatic method. The morphology and proliferative ability of the isolated cells were assessed using a doubling time (DT) assay from passages 3 to 6 (P3 - P6). We measured pluripotency gene expressions of cells in P2 using quantitative real-time polymerase chain reaction (qRT-PCR). To investigate MSC characteristics, a trilineage differentiation assay was conducted in P4, and cells in P4 were immunophenotyped using flow cytometry.

RESULTS

fEM-MSCs showed a typical spindle-shaped morphology under a microscope, and the DT was maintained from P3 to P6. fEM-MSCs could differentiate into adipocytes, osteoblasts, and chondrocytes, and expressed three pluripotency markers (OCT4, SOX2, and NANOG) by qRT-PCR. Immunophenotypic analysis showed that the fEM-MSCs were CD14 -, CD34 -, CD45 -, CD9+, and CD44+.

CONCLUSIONS

In this study, the feline endometrium was a novel source of MSCs, and to the best of our knowledge, this is the first report on the isolation method and characteristics of fEM-MSCs.

Adipose-Derived Stem Cells: Angiogenetic Potential and Utility in Tissue Engineering

Adipose tissue (AT) is a large and important energy storage organ as well as an endocrine organ with a critical role in many processes. Additionally, AT is an enormous and easily accessible source of multipotent cell types used in our day for all types of tissue regeneration. The ability of adipose-derived stem cells (ADSCs) to differentiate into other types of cells, such as endothelial cells (ECs), vascular smooth muscle cells, or cardiomyocytes, is used in tissue engineering in order to promote/stimulate the process of angiogenesis. Being a key for future successful clinical applications, functional vascular networks in engineered tissue are targeted by numerous in vivo and ex vivo studies. The article reviews the angiogenic potential of ADSCs and explores their capacity in the field of tissue engineering (TE).

Highly Concentrated Stabilized Hybrid Complexes of Hyaluronic Acid: Rheological and Biological Assessment of Compatibility with Adipose Tissue and Derived Stromal Cells towards Regenerative Medicine

Cells and extracts derived from adipose tissue are gaining increasing attention not only in plastic surgery and for aesthetic purposes but also in regenerative medicine. The ability of hyaluronan (HA) to support human adipose stromal cell (hASC) viability and differentiation has been investigated. However, the compatibility of adipose tissue with HA-based formulation in terms of biophysical and rheological properties has not been fully addressed, although it is a key feature for tissue integration and in vivo performance. In this study, the biophysical and biochemical properties of highly concentrated (45 mg/mL) high/low-molecular-weight HA hybrid cooperative complex were assessed with a further focus on the potential application in adipose tissue augmentation/regeneration. Specifically, HA hybrid complex rheological behavior was observed in combination with different adipose tissue ratios, and hyaluronidase-catalyzed degradation was compared to that of a high-molecular-weight HA (HHA). Moreover, the HA hybrid complex's ability to induce in vitro hASCs differentiation towards adipose phenotype was evaluated in comparison to HHA, performing Oil Red O staining and analyzing gene/protein expression of PPAR-γ, adiponectin, and leptin. Both treatments supported hASCs differentiation, with the HA hybrid complex showing better results. These outcomes may open new frontiers in regenerative medicine, supporting the injection of highly concentrated hybrid formulations in fat compartments, eventually enhancing residing staminal cell differentiation and improving cell/growth factor persistence towards tissue regeneration districts.

Encapsulation of pristine and silica-coated human adipose-derived mesenchymal stem cells in gelatin colloidal hydrogels for tissue engineering and bioprinting applications

Colloidal gels assembled from gelatin nanoparticles (GNPs) as particulate building blocks show strong promise to solve challenges in cell delivery and biofabrication, such as low cell survival and limited spatial retention. These gels offer evident advantages to facilitate cell encapsulation, but research on this topic is still limited, which hampers our understanding of the relationship between the physicochemical and biological properties of cell-laden colloidal gels. Human adipose-derived mesenchymal stem cells were successfully encapsulated in gelatin colloidal gels and evaluated their mechanical and biological performance over 7 days. The cells dispersed well within the gels without compromising gel cohesiveness, remained viable, and spread throughout the gels. Cells partially coated with silica were introduced into these gels, which increased their storage moduli and decreased their self-healing capacity after 7 days. This finding demonstrates the ability to modulate gel stiffness by incorporating cells partially coated with silica, without altering the solid content or introducing additional particles. Our work presents an efficient method for cell encapsulation while preserving gel integrity, expanding the applicability of colloidal hydrogels for tissue engineering and bioprinting. Overall, our study contributes to the design of improved cell delivery systems and biofabrication techniques.