Adipose Stem Cell Translational Applications: From Bench-to-Bedside

Application and Mechanism of Adipose Tissue-Derived Microvascular Fragments in Tissue Repair and Regeneration

One of the long-standing challenges in the field of tissue repair and regeneration is the rapid establishment of local microvascular circulation and restoration of perfusion at the site of defects or injuries. Recently, adipose tissue-derived microvascular fragments (ad-MVFs) have attracted increasing attention from researchers. Adipose tissue is rich in blood vessels, and significant progress has been made in the extraction and preservation techniques for microvascular fragments within it. Ad-MVFs promote tissue and organ repair and regeneration through three main mechanisms. First, they accelerate rapid and efficient vascularization at the injury site, enabling early vessel perfusion. Second, the stem cell components within ad-MVFs provide a rich source of cells for tissue and organ regeneration. Third, they play a role in immune regulation, facilitating integration with host tissues after implantation. The application methods of ad-MVFs are diverse. They can be directly implanted or pre-cultivated, facilitating their combination with various scaffolds and broadening their application scope. These properties have led to the wide use of ad-MVFs in tissue engineering, with promising prospects. This review demonstrates that ad-MVFs can serve as a reliable and highly feasible unit for tissue regeneration.

Advanced progress of adipose-derived stem cells-related biomaterials in maxillofacial regeneration

The tissue injury in maxillofacial region affects patients' physical function and specific mental health. This decade, utilizing regenerative medicine to achieve tissue regeneration has been proved a hopeful direction. Seed cells play a vital role in regeneration strategy. Among various kinds of stem cells that effectively to regenerate the soft and hard tissue of maxillofacial region, adipose-derived stem cells (ADSCs) have gained increasing interests of researchers due to their abundant sources, easy availability and multi-differentiation potentials in recent decades. Thus, this review focuses on the advances of ADSCs-based biomaterial in maxillofacial regeneration from the progress and strategies perspective. It is structured as introducing the properties of ADSCs, biomaterials (polymers, ceramics and metals) within ADSCs and the latest applications of ADSCs in maxillofacial regeneration, including temporomandibular joint (TMJ), bone, periodontal tissue, tooth, nerve as well as cosmetic field. In order to further facilitate ADSCs-based therapies as an emerging platform for regenerative medicine, this review also emphasized current challenges in translating ADSC-based therapies into clinical application and dissussed the strategies to solve these obstacles.

Non-Drug and Non-Invasive Therapeutic Options in Alzheimer's Disease

Despite the massive efforts of modern medicine to stop the evolution of Alzheimer's disease (AD), it affects an increasing number of people, changing individual lives and imposing itself as a burden on families and the health systems. Considering that the vast majority of conventional drug therapies did not lead to the expected results, this review will discuss the newly developing therapies as an alternative in the effort to stop or slow AD. Focused Ultrasound (FUS) and its derived Transcranial Pulse Stimulation (TPS) are non-invasive therapeutic approaches. Singly or as an applied technique to change the permeability of the blood-brain-barrier (BBB), FUS and TPS have demonstrated the benefits of use in treating AD in animal and human studies. Adipose-derived stem Cells (ADSCs), gene therapy, and many other alternative methods (diet, sleep pattern, physical exercise, nanoparticle delivery) are also new potential treatments since multimodal approaches represent the modern trend in this disorder research therapies.

Influence of Physical Exercise on the Rehabilitation of Volumetric Muscle Loss Injury Reconstructed with Autologous Adipose Tissue

BACKGROUND

In volumetric muscle loss (VML) injuries, spontaneous muscle regeneration capacity is limited. The implantation of autologous adipose tissue in the affected area is an option to treat these lesions; however, the effectiveness of this therapy alone is insufficient for a complete recovery of the damaged muscle. This study examined the influence of treadmill exercise on the rehabilitation of VML injuries reconstructed with autologous adipose tissue, as a strategy to counteract the limitations of spontaneous regeneration observed in these injuries.

METHODS

Forty adult male Wistar rats were divided into eight groups of five individuals each: normal control (NC), regenerative control (RC), VML control (VML), VML injury reconstructed with fresh autologous adipose tissue (FAT), exercise-rehabilitated control (RNC), exercise-rehabilitated regenerative control (RRC), exercise-rehabilitated VML injury (RVML), and exercise-rehabilitated VML injury reconstructed with fresh autologous adipose tissue (RFAT). Histological and histochemical staining techniques were used for the analysis of structural features and histomorphometric parameters of the tibialis anterior muscle. Grip strength tests were conducted to assess muscle force.

RESULTS

Exercise rehabilitation decreased the proportion of disoriented fibers in RFAT vs. FAT group. The percentage of fibrosis was significantly higher in FAT and RFAT groups versus NC and RNC groups but did not vary significantly between FAT and RFAT groups. Overall, muscle grip strength and fiber size increased significantly in the exercise-rehabilitated groups compared to control groups.

CONCLUSIONS

To conclude, rehabilitation with physical exercise tended to normalize the process of muscle repair in a model of VML injury reconstructed with fresh autologous adipose tissue, but it did not reduce the intense fibrosis associated with these injuries.

Urinary bladder matrix scaffold improves the impact of adipose-mesenchymal stem cells on the function and structure of transplanted rat ovaries

Ovarian transplantation presents significant advantages for the preservation of female fertility. Nonetheless, a substantial number of follicles are apoptosis during the process of ovarian tissue transplantation as a result of ischemic conditions. This study aimed to assess whether adipose-derived mesenchymal stem cells combined with urinary bladder matrix (ADSC/UBM) confer a greater therapeutic benefit compared to ADSCs alone. To achieve this, ADSC/UBM was applied during the autotransplantation of rat ovaries. Thirty rats were divided into five sets of six: the untreated control group (Normal), the oophorectomy group, the autograft group, the autograft + ADSCs group (ADSC), and the autograft + ADSC/UBM group (ADSC/UBM). After transplantation, the number of follicles in the ADSC/UBM group was significantly higher than that in the autograft group. Angiogenesis was enhanced following ADSC/UBM transplantation. Follicle-stimulating hormone (FSH) levels were significantly lower, and Anti-Müllerian hormone (AMH) levels were significantly higher in rats in the ADSC/UBM group than in the Autograft group. The apoptosis rate in the ADSC/UBM group decreased. The estrous cycle in the ADSC/UBM group recovered more quickly than the ADSC group. The data indicate that UBM improves ADSC retention in graft ovaries and aids in permanently restoring ovarian function, making ADSC/UBM a promising option for ovarian transplantation.

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.

Autologous Fat Transfer in Craniofacial Surgery

Over the past two decades, autologous fat transfer has garnered significant recognition and widespread adoption within esthetic and reconstructive surgical domains. In craniofacial surgery, fat transplantation is frequently employed to address soft tissue volumetric deficiencies and asymmetries that influence facial contours. While adipose tissue (AT) is widely regarded as an optimal choice for augmentation due to its abundant availability and biocompatibility, the unpredictability and heightened resorption rates observed with traditional lipofilling techniques present a challenge for clinicians. Adipose-derived stem cells (ASCs) housed within the grafted tissue play a pivotal role in graft survival and offer avenues for tissue repair due to their angiogenic, anti-inflammatory, and immunosuppressive properties. Micro Fragmentation of Adipose Tissue (MFAT), utilized in several FDA-approved processing devices, has demonstrated promising outcomes in treating osteoarthritic joints, with success primarily attributed to enhanced paracrine function of ASCs via preservation of the perivascular niche. Currently, its application for treating bone or articular defects in the craniofacial region, including abnormalities of the temporomandibular joint, remains limited. This scarcity underscores the need for further investigation prior to its widespread integration into clinical practice.

The influence of xeno-free culture conditions on the angiogenic and adipogenic differentiation properties of adipose tissue-derived stem cells

Introduction

Before performing cell therapy clinical trials, it is important to understand how cells are influenced by different growth conditions and to find optimal xeno-free medium formulations. In this study we have investigated the properties of adipose tissue-derived stem cells (ASCs) cultured under xeno-free conditions.

Methods

Human lipoaspirate samples were digested to yield the stromal vascular fraction cells which were then seeded in i) Minimum Essential Medium-α (MEM-α) supplemented with 10 % (v/v) fetal bovine serum (FBS), ii) MEM-α supplemented with 2 % (v/v) human platelet lysate (PLT) or iii) PRIME-XV MSC expansion XSFM xeno-free, serum free medium (XV). Flow cytometry for ASCs markers CD73, CD90 and CD105 together with the putative pericyte marker CD146 was performed. Growth rates were monitored over multiple passages and adipogenic differentiation performed at early and expanded passage culture. Growth factor gene expression was analyzed and an in vitro angiogenesis assay performed.

Results

Cells in FBS and PLT grew at similar rates whereas the cells cultured in XV medium proliferated significantly faster up to 60 days in culture. All cultures were >98 % positive for CD73, CD90 and CD105, whereas CD146 expression was significantly higher in XV cells. Adipogenic differentiation was most pronounced in cells which had been cultured in XV medium whilst cells grown in PLT were inferior compared with cells from the FBS cultures. IGF1 gene expression was highest in cells cultured in PLT whilst cells grown in XV medium showed 10-fold lower expression compared with FBS cells. In contrast, HGF gene expression was 90-fold greater in cells cultured in XV medium compared with those cultured in FBS. Conditioned medium from XV cultured cells showed the most angiogenic activity, inducing the greatest endothelial cell network formation and maturation.

Conclusion

Culture under different conditions alters the ASCs characteristics. Since cells cultured in XV medium showed the best adipogenic and angiogenic profile this might be a preferred medium formulation for preparing cells required for reconstructive surgical applications such as cell-assisted fat grafting.

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.

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.

Engineered phalangeal grafts for children with symbrachydactyly: A proof of concept

Tissue engineering approaches hold great promise in the field of regenerative medicine, especially in the context of pediatric applications, where ideal grafts need to restore the function of the targeted tissue and consider growth. In the present study, we aimed to develop a protocol to engineer autologous phalangeal grafts of relevant size for children suffering from symbrachydactyly. This condition results in hands with short fingers and missing bones. A previously-described, developmentally-inspired strategy based on endochondral ossification (ECO)-the main pathway leading to bone and bone marrow development-and adipose derived-stromal cells (ASCs) as the source of chondroprogenitor was used. First, we demonstrated that pediatric ASCs associated with collagen sponges can generate hypertrophic cartilage tissues (HCTs) in vitro that remodel into bone tissue in vivo via ECO. Second, we developed and optimized an in vitro protocol to generate HCTs in the shape of small phalangeal bones (108-390 mm3) using freshly isolated adult cells from the stromal vascular fraction (SVF) of adipose tissue, associated with two commercially available large collagen scaffolds (Zimmer Plug® and Optimaix 3D®). We showed that after 12 weeks of in vivo implantation in an immunocompromised mouse model such upscaled grafts remodeled into bone organs (including bone marrow tissues) retaining the defined shape and size. Finally, we replicated similar outcome (albeit with a slight reduction in cartilage and bone formation) by using minimally expanded pediatric ASCs (3 × 106 cells per grafts) in the same in vitro and in vivo settings, thereby validating the compatibility of our pediatric phalanx engineering strategy with a clinically relevant scenario. Taken together, these results represent a proof of concept of an autologous approach to generate osteogenic phalangeal grafts of pertinent clinical size, using ASCs in children born with symbrachydactyly, despite a limited amount of tissue available from pediatric patients.

Harnessing human adipose-derived stromal cell chondrogenesis in vitro for enhanced endochondral ossification

Endochondral ossification (ECO), the major ossification process during embryogenesis and bone repair, involves the formation of a cartilaginous template remodelled into a functional bone organ. Adipose-derived stromal cells (ASC), non-skeletal multipotent progenitors from the stromal vascular fraction (SVF) of human adipose tissue, were shown to recapitulate ECO and generate bone organs in vivo when primed into a hypertrophic cartilage tissue (HCT) in vitro. However, the reproducibility of ECO was limited and the major triggers remain unknown. We studied the effect of the expansion of cells and maturation of HCT on the induction of the ECO process. SVF cells or expanded ASC were seeded onto collagen sponges, cultured in chondrogenic medium for 3-6 weeks and implanted ectopically in nude mice to evaluate their bone-forming capacities. SVF cells from all tested donors formed mature HCT in 3 weeks whereas ASC needed 4-5 weeks. A longer induction increased the degree of maturation of the HCT, with a gradually denser cartilaginous matrix and increased mineralization. This degree of maturation was highly predictive of their bone-forming capacity in vivo, with ECO achieved only for an intermediate maturation degree. In parallel, expanding ASC also resulted in an enrichment of the stromal fraction characterized by a rapid change of their proteomic profile from a quiescent to a proliferative state. Inducing quiescence rescued their chondrogenic potential. Our findings emphasize the role of monolayer expansion and chondrogenic maturation degree of ASC on ECO and provides a simple, yet reproducible and effective approach for bone formation to be tested in specific clinical models.

The effect of chemotherapy and radiotherapy on stem cells and wound healing. Current perspectives and challenges for cell-based therapies

Cancers are part of the group of diseases that carry a high mortality rate. According to World Health Organization in 2020 reported 10 million deaths due to cancers. Treatment of oncological patients is focused on chemotherapeutic agents, radiology, or immunology. Surgical interventions are also an important aspect of treatment. The above methods contribute to saving the patients' health and lives. However, cancer treatment possesses side effects. Commonly observed complications are hair loss, mucositis, nausea, diarrhea, or various skin damage. To improve the quality of medical care for cancer patients, new methods of reducing side effects are sought. Strategies include the use of stem cells (SCs). Due to unlimited proliferation potential and differentiating abilities, SCs are used in the treatment of many disease entities, including wounds. One of the most used types of stem cells supposed adipose-derived mesenchymal stromal cells (AD-MSCs). Clinical trials confirm the application of AD-MSCs in wound healing. Furthermore, in vivo studies considered the utilization of AD-MSCs in radiation injury. The use of stem cells in cancer treatment still involves many questions, such as the impact of treatment on SCs' condition and oncological safety. However, development in regenerative medicine research may contribute to the use of stem cells in personalized medicine, customized for the patient. This could represent a breakthrough step in preventing the side effects of cancer therapies, including chronic wounds.

An Update on Adipose-Derived Stem Cells for Regenerative Medicine: Where Challenge Meets Opportunity

Over the last decade, adipose-derived stem cells (ADSCs) have attracted increasing attention in the field of regenerative medicine. ADSCs appear to be the most advantageous cell type for regenerative therapies owing to their easy accessibility, multipotency, and active paracrine activity. This review highlights current challenges in translating ADSC-based therapies into clinical settings and discusses novel strategies to overcome the limitations of ADSCs. To further establish ADSC-based therapies as an emerging platform for regenerative medicine, this review also provides an update on the advancements in this field, including fat grafting, wound healing, bone regeneration, skeletal muscle repair, tendon reconstruction, cartilage regeneration, cardiac repair, and nerve regeneration. ADSC-based therapies are expected to be more tissue-specific and increasingly important in regenerative medicine.

Tight Regulation of Mechanotransducer Proteins Distinguishes the Response of Adult Multipotent Mesenchymal Cells on PBCE-Derivative Polymer Films with Different Hydrophilicity and Stiffness

Mechanotransduction is a molecular process by which cells translate physical stimuli exerted by the external environment into biochemical pathways to orchestrate the cellular shape and function. Even with the advancements in the field, the molecular events leading to the signal cascade are still unclear. The current biotechnology of tissue engineering offers the opportunity to study in vitro the effect of the physical stimuli exerted by biomaterial on stem cells and the mechanotransduction pathway involved in the process. Here, we cultured multipotent human mesenchymal/stromal cells (hMSCs) isolated from bone marrow (hBM-MSCs) and adipose tissue (hASCs) on films of poly(butylene 1,4-cyclohexane dicarboxylate) (PBCE) and a PBCE-based copolymer containing 50 mol% of butylene diglycolate co-units (BDG50), to intentionally tune the surface hydrophilicity and the stiffness (PBCE = 560 Mpa; BDG50 = 94 MPa). We demonstrated the activated distinctive mechanotransduction pathways, resulting in the acquisition of an elongated shape in hBM-MSCs on the BDG50 film and in maintaining the canonical morphology on the PBCE film. Notably, hASCs acquired a new, elongated morphology on both the PBCE and BDG50 films. We found that these events were mainly due to the differences in the expression of Cofilin1, Vimentin, Filamin A, and Talin, which established highly sensitive machinery by which, rather than hASCs, hBM-MSCs distinguished PBCE from BDG50 films.

Pituitary Adenylate Cyclase-activating Polypeptide (PACAP) -derived Peptide MPAPO Stimulates Adipogenic Differentiation by Regulating the Early Stage of Adipogenesis and ERK Signaling Pathway

Regenerative medicine and tissue engineering have delivered new healing possibilities to the treatment of soft tissue defects, but the selection of seed cells is critical for treatment. Adipose-derived stem cells have perpetually been a preferred candidate for seed cells due to their wealthy sources, simple access, high plasticity, and powerful value-added capabilities. How to improve the efficiency of adipogenic differentiation is the key to the treatment. Pituitary adenylate cyclase-activating peptide, as a biologically active peptide secreted by the pituitary, is widely involved in regulating the body's sugar metabolism and lipid metabolism. However, the effects of MPAPO in ADSCs adipogenic differentiation remain unknown. Our results reveal that MPAPO treatment improves the adipogenic differentiation efficiency of ADSCs, including promoting the accumulation of lipid droplets and triglycerides, and the expression of adipocyte protein biomarkers PPARγ and C/EBPa. Additionally, the mechanism studies showed that the effective window of MPAPO-induced adipogenesis was the first 3 days during ADSCs differentiation. MPAPO selectively binds to the PAC1 receptor and promotes adipogenic differentiation of ADSCs by activating the ERK signaling pathway and elevating cell proliferation during postconfluent mitosis stage. Altogether, we demonstrate that MPAPO plays a crucial role in ADSCs adipogenesis, providing experimental basis and data for exploring therapeutic options in tissue defect repair.

Thermal treatment of magnesium particles in polylactic acid polymer films elicits the expression of osteogenic differentiation markers and lipidome profile remodeling in human adipose stem cells

The efficacy of polylactic acid (PLA)/Magnesium (Mg)-based materials for driving stem cells toward bone tissue engineering applications requires specific Mg surface properties to modulate the interface of stem cells with the film. Here, we have developed novel PLA/Mg-based composites and explored their osteogenic differentiation potential on human adipose stem cells (hASCs). Mg-particles/polymer interface was improved by two treatments: heating in oxidative atmosphere (TT) and surface modification with a compatibilizer (PEI). Different contents of Mg particles were dispersed in PLA and composite surface and bulk properties, protein adsorption, stem cell-PLA/Mg interactions, osteogenic markers expressions, and lipids composition profile were evaluated. Mg particles were uniformly distributed on the surface and in the bulk PLA polymer. Improved and modulated particle-polymer adhesion was observed in Mg particle-treated composites. After 21 days in canonical growth culture conditions, hASCs on PLA/MgTT displayed the highest expression of the general osteogenic markers, RUNX2, SSP1, and BGLAP genes, Alkaline Phosphatase, type I Collagen, Osteopontin, and Calcium deposits. Moreover, by LC/MS QTOF mass-spectrophotometry lipidomic analysis, we found in PLA/MgTT-cells, for the first time, a remodeling of the lipid classes composition associated with the osteogenic differentiation. We ascribed these results to MgTT characteristics, which improve Mg availability and composite osteoinductive performance.

MiR-181a-5p Delivered by Adipose-Derived Mesenchymal Stem Cell Exosomes Alleviates Klebsiella pneumonia Infection-Induced Lung Injury by Targeting STAT3 Signaling

Background

Klebsiella pneumoniae (K. pneu) is a leading cause of gram-negative pneumonia, which requires effective treatment. Adipose-derived mesenchymal stem cell- (ADSC-) derived exosomal microRNAs (miRNAs) have presented the inhibitory effect of multiple diseases. However, the function of ADSC-derived exosomal miRNAs in K. pneu remains unclear.

Aim

In this study, we aimed to explore the effect of ADSC-derived exosomal miR-181-5p on K. pneu infection-induced lung injury.

Methods

C57BL/6 mouse model was established by infection of K. pneu. ADSCs and exosomes were extracted and characterized in vitro. The translocation of ADSC-derived exosomes to bone marrow-derived macrophages (BMDMs) was detected. The level of miR-181a-5p was detected by real-time PCR. The secretion of inflammatory factors was determined by ELISA. The interaction between miR-181a-5p with STAT3 was identified.

Results

We successfully isolated the ADSCs that express positive markers CD90 and CD105 rather than CD31 and CD45. The exosomal miR-181a-5p secreted by ADSCs were internalized by BMDM and K. pneu infection stimulated the miR-181a-5p level in bronchoalveolar lavage fluid (BALF) and BMDM. ADSC-derived exosomal miR-181a-5p repressed pulmonary outgrowth and dissemination of K. pneu infection in mice, repressed cellular infiltration in lung tissue, and attenuated the inflammasome activity and the levels of IL-1β and IL-18 in the lung. Mechanically, miR-181a-5p was able to inhibit STAT3 expression at posttranscriptional levels and repressed Nlrp3 and Asc expression in BMDM.

Conclusion

Consequently, we concluded that ADSC-derived exosomal miR-181a-5p alleviated Klebsiella pneumonia infection-induced lung injury by targeting STAT3 signaling. ADSC-derived exosomal miR-181a-5p may serve as a potential candidate for the treatment of Klebsiella pneumonia infection-induced lung injury.

Volumetric mass density measurements of mesenchymal stem cells in suspension using a density meter

To use regeneratively active cells for cell therapeutic applications, the cells must be isolated from their resident tissues. Different isolation procedures subject these cells to varying degrees of mechanical strain, which can affect the yield of cell number and viability. Knowledge of cell volumetric mass density is important for experimental and numerical optimization of these procedures. Although methods for measuring cell volumetric mass density already exist, they either consume much time and cell material or require a special setup. Therefore, we developed a user-friendly method that is based on the use of readily available instrumentation. The newly developed method is predicated on the linear relationship between the volumetric mass density of the cell suspension and the volumetric mass density, number, and diameter of the cells in the suspension. We used this method to determine the volumetric mass density of mesenchymal stem cells (MSCs) and compared it to results from the established density centrifugation.

Mesenchymal Stem Cells in Burn Wound Management

Mesenchymal stem cells have a known regenerative potential and are used in many indications. They secrete many growth factors, including for fibroblasts (FGF), endothelium (VEGF), as well as 14 anti-inflammatory cytokines, and they stimulate tissue regeneration, promoting the secretion of proteins and glycosaminoglycans of extracellular matrices, such as collagen I, II, III, and V, elastin, and also metalloproteinases. They secrete exosomes that contain proteins, nucleic acids, lipids, and enzymes. In addition, they show the activity of inactivating free radicals. The aim of this study was an attempt to collect the existing literature on the use of stem cells in the treatment of a burn wound. There were 81 studies included in the analysis. The studies differed in terms of the design, burn wound model, source of stem cells, and methods of cellular therapy application. No major side effects were reported, and cellular therapy reduced the healing time of the burn wound. Few case reports on human models did not report any serious adverse events. However, due to the heterogeneity of the evidence, cellular therapy in burn wound treatment remains an experimental method.

In vitro testing and efficacy of poly-lactic acid coating incorporating antibiotic loaded coralline bioceramic on Ti6Al4V implant against Staphylococcus aureus

Biofilm formation on an implant surface is most commonly caused by the human pathogenic bacteria Staphylococcus aureus, which can lead to implant related infections and failure. It is a major problem for both implantable orthopedic and maxillofacial devices. The current antibiotic treatments are typically delivered orally or in an injectable form. They are not highly effective in preventing or removing biofilms, and they increase the risk of antibiotic resistance of bacteria and have a dose-dependent negative biological effect on human cells. Our aim was to improve current treatments via a localized and controlled antibiotic delivery-based implant coating system to deliver the antibiotic, gentamicin (Gm). The coating contains coral skeleton derived hydroxyapatite powders (HAp) that act as antibiotic carrier particles and have a biodegradable poly-lactic acid (PLA) thin film matrix. The system is designed to prevent implant related infections while avoiding the deleterious effects of high concentration antibiotics in implants on local cells including primary human adipose derived stem cells (ADSCs). Testing undertaken in this study measured the rate of S. aureus biofilm formation and determined the growth rate and proliferation of ADSCs. After 24 h, S. aureus biofilm formation and the percentage of live cells found on the surfaces of all 5%-30% (w/w) PLA-Gm-(HAp-Gm) coated Ti6Al4V implants was lower than the control samples. Furthermore, Ti6Al4V implants coated with up to 10% (w/w) PLA-Gm-(HAp-Gm) did not have noticeable Gm related adverse effect on ADSCs, as assessed by morphological and surface attachment analyses. These results support the use and application of the antibacterial PLA-Gm-(HAp-Gm) thin film coating design for implants, as an antibiotic release control mechanism to prevent implant-related infections.

The role of BMP4 in adipose-derived stem cell differentiation: A minireview

Bone morphogenetic protein 4 (BMP4) is a member of the transforming growth factor beta (TGF-β) superfamily of cytokines responsible for stem cells’ commitment to differentiation, proliferation, and maturation. To date, various studies have utilized BMP4 as a chemical inducer for in vitro differentiation of human mesenchymal stem cells (MSCs) based on its potential. BMP4 drives in vitro differentiation of ADSC via TGF-β signaling pathway by interactions with BMP receptors leading to the activation of smad-dependent and smad-independent pathways. The BMP4 signaling pathways are regulated by intracellular and extracellular BMP4 antagonists. Extracellular BMP4 antagonist prevents interaction between BMP4 ligand to its receptors, while intracellular BMP4 antagonist shutdowns the smad-dependent pathways through multiple mechanisms. BMP4 proved as one of the popular differentiation factors to induce ADSC differentiation into cell from mesodermal origin. However, addition of all-trans retinoic acid is also needed in trans-differentiation of ADSC into ectodermal lineage cells. Suggesting that both BMP4 and RA signaling pathways may be necessary to be activated for in vitro trans-differentiation of ADSC.

Itaconic Acid as A Differential Transcription Regulator of Apoptosis and Autophagy Pathways Genes: A Rat Adipose Mesenchymal Stem Cells Model

OBJECTIVE

Itaconate, a novel regulatory immunometabolite, is synthesized by inflammatory macrophage. It acts as an anti-inflammatory mediator and regulates several metabolic and signaling pathways particularly Nrf2 pathway. The immunometabolites can affect the stemness potency, differentiation ability and viability of stem cells, but little is known about the critical function of Itaconate on the stem cell fate. The objective of the present study was to determine the regulatory effects of Itaconic acid on the cell viability and transcription of apoptosis and autophagy pathways genes in the rat adipose derived mesenchymal stem cells (ADMSCs).

MATERIALS AND METHODS

In this experimental study, the ADMSCs were incubated with 125 μM and 250 μM dimethyl itaconate (DMI) for 24 hours or 48 hours. The expression of apoptosis pathway genes (Bax, Bcl2, Caspase 3, Fas, Fadd and Caspase 8) and autophagy pathway genes (Atg12, Atg5, Beclin, Lc3b and P62) were determined using real time polymerase chain reaction (PCR) assay. Using the ELISA method, cellular level of phospho-NRF2 protein was measured.

RESULTS

The results indicated that DMI increased the expression of NRF2 protein, altered the expression of some apoptosis genes (Fadd, Bax and Bcl2), and changed the expression of some autophagy related genes (Lc3b, Becline and P62) in ADMSCs. DMI had no obvious effect on the transcription of caspases enzymes.

CONCLUSION

Because autophagy activation and apoptosis suppression can protect stem cells against environmental stress, it seems Itaconate can affect the functions and viability of ADMSCs via converse regulation of these pathways.

Inhibitory effect of saffron, crocin, crocetin, and safranal against adipocyte differentiation in human adipose-derived stem cells

ETHNOPHARMACOLOGICAL RELEVANCE

Saffron (Crocus sativus L.) has been introduced as a potential promising natural antioxidant with anti-obesity properties. In Persian Medicine, saffron has been used to control appetite and obesity.

AIM OF THE STUDY

The present study aims to investigate the effect of saffron and its bioactive compounds on adipocyte differentiation in human adipose-derived stem cells (ADSCs).

MATERIALS AND METHODS

Flow-Cytometric analysis was performed to quantify the cell surface markers. The extracts cytotoxicity on hASCs was measured using alamarBlue® assay whereas their activities against adipocyte differentiation were studied using Oil Red O staining. The level of Peroxisome proliferator-activated receptor-γ (PPARγ), Fatty Acid Synthetase (FAS), and Glyceraldehyde-3-phosphate dehydrogenase (GAPHD) which are key proteins in cell differentiation was investigated by western blot analysis.

RESULTS

Flow-cytometry revealed the mesenchymal stem cells markers, CD44 and CD90, on ADSCs surface. The saffron, crocin, and crocetin significantly inhibited adipocyte differentiation while saffron up to 20 μg/mL and crocin, crocetin and safranal up to 20 μM did not exhibit cytotoxicity. The western blotting analysis revealed a remarkable reduction in the level of PPARγ, GAPDH, and FAS proteins by 10 and 20 μM of crocin and 2.5 and 5 μM of crocetin.

CONCLUSION

It seems that saffron, crocin, and crocetin could efficiently inhibit the differentiation of hASCs with benefits for the treatment and prevention of obesity.

Adipose‑derived mesenchymal stem cell‑derived HCAR1 regulates immune response in the attenuation of sepsis

Sepsis serves as a leading cause of admission to and death of patients in the intensive care unit (ICU) and is described as a systemic inflammatory response syndrome caused by abnormal host response to infection. Adipose‑derived mesenchymal stem cells (ADSCs) have exhibited reliable and promising clinical application potential in multiple disorders. However, the function and the mechanism of ADSCs in sepsis remain elusive. In the present study, the crucial inhibitory effect of ADSC‑derived hydroxy‑carboxylic acid receptor 1 (HCAR1) on sepsis was identified. Reverse transcription quantitative‑PCR determined that the mRNA expression of HCAR1 was reduced while the mRNA expression of Toll‑like receptor 4 (TLR4), major histocompatibility complex class II (MHC II), NOD‑like receptor family pyrin domain containing 3 (NLRP3), and the levels of interleukin‑1β (IL‑1β), tumor necrosis factor‑α (TNF‑α), interleukin‑10 (IL‑10), and interleukin‑18 (IL‑18) were enhanced in the peripheral blood of patients with sepsis. The expression of HCAR1 was negatively correlated with TLR4 (r=‑0.666), MHC II (r=‑0.587), and NLRP3 (r=‑0.621) expression and the expression of TLR4 was positively correlated with NLRP3 (r=0.641), IL‑1β (r=0.666), TNF‑α (r=0.606), and IL‑18 (r=0.624) levels in the samples. Receiver operating characteristic (ROC) curve analysis revealed that the area under the ROC curve (AUC) of HCAR1, TLR4, MHC II and NLRP3 mRNA expression was 0.830, 0.853, 0.735 and 0.945, respectively, in which NLRP3 exhibited the highest diagnostic value, and the AUC values of IL‑1β, IL‑18, TNF‑α, and IL‑10 were 0.751, 0.841, 0.924 and 0.729, respectively, in which TNF‑α exhibited the highest diagnostic value. A sepsis rat model was established by injecting lipopolysaccharide (LPS) and the rats were randomly divided into 5 groups, including a normal control group (NC group; n=6), a sepsis model group (LPS group; n=6), an ADSC transplantation group (L + M group; n=6), a combined HCAR1 receptor agonist group [L + HCAR1 inducer (Gi) + M group; n=6], and a combined HCAR1 receptor inhibitor group [L + HCAR1 blocker (Gk) + M group; n=6]. Hematoxylin and eosin staining determined that ADSCs attenuated the lung injury of septic rats and ADSC‑derived HCAR1 enhanced the effect of ADSCs. The expression of HCAR1, TLR4, MHC II, NLRP3, IL‑1β, IL‑18 and TNF‑α levels were suppressed by ADSCs and the effect was further induced by ADSC‑derived HCAR1. However, ADSC‑derived HCAR1 induced the levels of anti‑inflammatory factor IL‑10. The negative correlation of HCAR1 expression with TLR4, MHC II, and NLRP3 expression in the peripheral blood and lung tissues of the rats was then identified. It is thus concluded that ADSC‑derived HCAR1 regulates immune response in the attenuation of sepsis. ADSC‑derived HCAR1 may be a promising therapeutic strategy for sepsis.

The Emerging Use of ASC/Scaffold Composites for the Regeneration of Osteochondral Defects

Articular cartilage is composed of chondrocytes surrounded by a porous permeable extracellular matrix. It has a limited spontaneous healing capability post-injury which, if left untreated, can result in severe osteochondral disease. Currently, osteochondral (OC) defects are treated by bone marrow stimulation, artificial joint replacement, or transplantation of bone, cartilage, and periosteum, while autologous osteochondral transplantation is also an option; it carries the risk of donor site damage and is limited only to the treatment of small defects. Allografts may be used for larger defects; however, they have the potential to elicit an immune response. A possible alternative solution to treat osteochondral diseases involves the use of stromal/stem cells. Human adipose-derived stromal/stem cells (ASCs) can differentiate into cartilage and bone cells. The ASC can be combined with both natural and synthetic scaffolds to support cell delivery, growth, proliferation, migration, and differentiation. Combinations of both types of scaffolds along with ASCs and/or growth factors have shown promising results for the treatment of OC defects based on in vitro and in vivo experiments. Indeed, these findings have translated to several active clinical trials testing the use of ASC-scaffold composites on human subjects. The current review critically examines the literature describing ASC-scaffold composites as a potential alternative to conventional therapies for OC tissue regeneration.

AD-MSCs and BM-MSCs Ameliorating Effects on The Metabolic and Hepato-renal Abnormalities in Type 1 Diabetic Rats

Diabetes mellitus (DM) is one of the most serious threats in the 21th century throughout the human population that needs to be addressed cautiously. Nowadays, stem cell injection is considered among the most promising protocols for DM therapy; owing to its marked tissues and organs repair capability. Therefore, our 4 weeks study was undertaken to elucidate the probable beneficial effects of two types of adult mesenchymal stem cells (MSCs) on metabolism disturbance and some tissue function defects in diabetic rats. Animals were classified into 4 groups; the control group, the diabetic group, the diabetic group received a single dose of adipose tissue-derived MSCs and the diabetic group received a single dose of bone marrow-derived MSCs. Herein, both MSCs treated groups markedly reduced hyperglycemia resulting from diabetes induction via lowering serum glucose and rising insulin and C-peptide levels, compared to the diabetic group. Moreover, the increased lipid fractions levels were reverted back to near normal values as a consequence to MSCs injection compared to the diabetic untreated rats. Furthermore, both MSCs types were found to have hepato-renal protective effects indicated through the decreased serum levels of both liver and kidney functions markers in the treated diabetic rats. Taken together, our results highlighted the therapeutic benefits of both MSCs types in alleviating metabolic anomalies and hepato-renal diabetic complications.

Sequential growth factor exposure of human Ad-MSCs improves chondrogenic differentiation in an osteochondral biphasic implant

Joint cartilage damage affects 10-12% of the world's population. Medical treatments improve the short-term quality of life of affected individuals but lack a long-term effect due to injury progression into fibrocartilage. The use of mesenchymal stem cells (MSCs) is one of the most promising strategies for tissue regeneration due to their ability to be isolated, expanded and differentiated into metabolically active chondrocytes to achieve long-term restoration. For this purpose, human adipose-derived MSCs (Ad-MSCs) were isolated from lipectomy and grown in xeno-free conditions. To establish the best differentiation potential towards a stable chondrocyte phenotype, isolated Ad-MSCs were sequentially exposed to five differentiation schemes of growth factors in previously designed three-dimensional biphasic scaffolds with incorporation of a decellularized cartilage matrix as a bioactive ingredient, silk fibroin and bone matrix, to generate a system capable of being loaded with pre-differentiated Ad-MSCs, to be used as a clinical implant in cartilage lesions for tissue regeneration. Chondrogenic and osteogenic markers were analyzed by reverse transcription-quantitative PCR and cartilage matrix generation by histology techniques at different time points over 40 days. All groups had an increased expression of chondrogenic markers; however, the use of fibroblast growth factor 2 (10 ng/ml) followed by a combination of insulin-like growth factor 1 (100 ng/ml)/TGFβ1 (10 ng/ml) and a final step of exposure to TGFβ1 alone (10 ng/ml) resulted in the most optimal chondrogenic signature towards chondrocyte differentiation and the lowest levels of osteogenic expression, while maintaining stable collagen matrix deposition until day 33. This encourages their possible use in osteochondral lesions, with appropriate properties for use in clinical patients.

Interfacial Compatibilization into PLA/Mg Composites for Improved In Vitro Bioactivity and Stem Cell Adhesion

The present work highlights the crucial role of the interfacial compatibilization on the design of polylactic acid (PLA)/Magnesium (Mg) composites for bone regeneration applications. In this regard, an amphiphilic poly(ethylene oxide-b-L,L-lactide) diblock copolymer with predefined composition was synthesised and used as a new interface to provide physical interactions between the metallic filler and the biopolymer matrix. This strategy allowed (i) overcoming the PLA/Mg interfacial adhesion weakness and (ii) modulating the composite hydrophilicity, bioactivity and biological behaviour. First, a full study of the influence of the copolymer incorporation on the morphological, wettability, thermal, thermo-mechanical and mechanical properties of PLA/Mg was investigated. Subsequently, the bioactivity was assessed during an in vitro degradation in simulated body fluid (SBF). Finally, biological studies with stem cells were carried out. The results showed an increase of the interfacial adhesion by the formation of a new interphase between the hydrophobic PLA matrix and the hydrophilic Mg filler. This interface stabilization was confirmed by a decrease in the damping factor (tanδ) following the copolymer addition. The latter also proves the beneficial effect of the composite hydrophilicity by selective surface localization of the hydrophilic PEO leading to a significant increase in the protein adsorption. Furthermore, hydroxyapatite was formed in bulk after 8 weeks of immersion in the SBF, suggesting that the bioactivity will be noticeably improved by the addition of the diblock copolymer. This ceramic could react as a natural bonding junction between the designed implant and the fractured bone during osteoregeneration. On the other hand, a slight decrease of the composite mechanical performances was noted.

Stem Cell-Derived Exosomes Potential Therapeutic Roles in Cardiovascular Diseases

Owing to myocardial abnormalities, cardiac ailments are considered to be the major cause of morbidity and mortality worldwide. According to a recent study, membranous vesicles that are produced naturally, termed as "exosomes", have emerged as the potential candidate in the field of cardiac regenerative medicine. A wide spectrum of stem cells has also been investigated in the treatment of cardiovascular diseases (CVD). Exosomes obtained from the stem cells are found to be cardioprotective and offer great hope in the treatment of CVD. The basic nature of exosomes is to deal with the intracellular delivery of both proteins and nucleic acids. This activity of exosomes helps us to rely on them as the attractive pharmaceutical delivery agents. Most importantly, exosomes derived from microRNAs (miRNAs) hold great promise in assessing the risk of CVD, as they serve as notable biomarkers of the disease. Exosomes are small, less immunogenic, and lack toxicity. These nanovesicles harbor immense potential as a therapeutic entity and would provide fruitful benefits if consequential research were focused on their upbringing and development as a useful diagnostic and therapeutic tool in the field of medicine.

Induction of the CD24 Surface Antigen in Primary Undifferentiated Human Adipose Progenitor Cells by the Hedgehog Signaling Pathway

In the murine model system of adipogenesis, the CD24 cell surface protein represents a valuable marker to label undifferentiated adipose progenitor cells. Indeed, when injected into the residual fat pads of lipodystrophic mice, these CD24 positive cells reconstitute a normal white adipose tissue (WAT) depot. Unluckily, similar studies in humans are rare and incomplete. This is because it is impossible to obtain large numbers of primary CD24 positive human adipose stem cells (hASCs). This study shows that primary hASCs start to express the glycosylphosphatidylinositol (GPI)-anchored CD24 protein when cultured with a chemically defined medium supplemented with molecules that activate the Hedgehog (Hh) signaling pathway. Therefore, this in vitro system may help understand the biology and role in adipogenesis of the CD24-positive hASCs. The induced cells’ phenotype was studied by flow cytometry, Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR) techniques, and their secretion profile. The results show that CD24 positive cells are early undifferentiated progenitors expressing molecules related to the angiogenic pathway.

Adipose Tissue: Understanding the Heterogeneity of Stem Cells for Regenerative Medicine

Adipose-derived stem cells (ASCs) have been increasingly used as a versatile source of mesenchymal stem cells (MSCs) for diverse clinical investigations. However, their applications often become complicated due to heterogeneity arising from various factors. Cellular heterogeneity can occur due to: (i) nomenclature and criteria for definition; (ii) adipose tissue depots (e.g., subcutaneous fat, visceral fat) from which ASCs are isolated; (iii) donor and inter-subject variation (age, body mass index, gender, and disease state); (iv) species difference; and (v) study design (in vivo versus in vitro) and tools used (e.g., antibody isolation and culture conditions). There are also actual differences in resident cell types that exhibit ASC/MSC characteristics. Multilineage-differentiating stress-enduring (Muse) cells and dedifferentiated fat (DFAT) cells have been reported as an alternative or derivative source of ASCs for application in regenerative medicine. In this review, we discuss these factors that contribute to the heterogeneity of human ASCs in detail, and what should be taken into consideration for overcoming challenges associated with such heterogeneity in the clinical use of ASCs. Attempts to understand, define, and standardize cellular heterogeneity are important in supporting therapeutic strategies and regulatory considerations for the use of ASCs.

The role of physical cues in the development of stem cell-derived organoids

Organoids are a novel three-dimensional stem cells’ culture system that allows the in vitro recapitulation of organs/tissues structure complexity. Pluripotent and adult stem cells are included in a peculiar microenvironment consisting of a supporting structure (an extracellular matrix (ECM)-like component) and a cocktail of soluble bioactive molecules that, together, mimic the stem cell niche organization. It is noteworthy that the balance of all microenvironmental components is the most critical step for obtaining the successful development of an accurate organoid instead of an organoid with heterogeneous morphology, size, and cellular composition. Within this system, mechanical forces exerted on stem cells are collected by cellular proteins and transduced via mechanosensing—mechanotransduction mechanisms in biochemical signaling that dictate the stem cell specification process toward the formation of organoids. This review discusses the role of the environment in organoids formation and focuses on the effect of physical components on the developmental system. The work starts with a biological description of organoids and continues with the relevance of physical forces in the organoid environment formation. In this context, the methods used to generate organoids and some relevant published reports are discussed as examples showing the key role of mechanosensing–mechanotransduction mechanisms in stem cell-derived organoids.

Extracellular vesicle activities regulating macrophage- and tissue-mediated injury and repair responses

Macrophages are typically identified as classically activated (M1) macrophages and alternatively activated (M2) macrophages, which respectively exhibit pro- and anti-inflammatory phenotypes, and the balance between these two subtypes plays a critical role in the regulation of tissue inflammation, injury, and repair processes. Recent studies indicate that tissue cells and macrophages interact via the release of small extracellular vesicles (EVs) in processes where EVs released by stressed tissue cells can promote the activation and polarization of adjacent macrophages which can in turn release EVs and factors that can promote cell stress and tissue inflammation and injury, and vice versa. This review discusses the roles of such EVs in regulating such interactions to influence tissue inflammation and injury in a number of acute and chronic inflammatory disease conditions, and the potential applications, advantage and concerns for using EV-based therapeutic approaches to treat such conditions, including their potential role of drug carriers for the treatment of infectious diseases.

Therapeutic potential of small extracellular vesicles derived from lipoma tissue in adipose tissue regeneration-an in vitro and in vivo study

OBJECTIVE

To explore the adipogenic effects of the small extracellular vesicles derived from the lipoma tissues (sEV-LT), and to find a new cell-free therapeutic approach for adipose tissue regeneration.

METHODS

Adipose tissue-derived stem cells (ADSCs) and small extracellular vesicles derived from the adipose tissues (sEV-AT) were isolated from human adipose tissue, while sEV-LT were isolated from human lipomatous tissue. ADSCs were characterized by using flow cytometric analysis and adipogenic and osteogenic differentiation assays. sEV was identified by electron microscopy, nanoparticle tracking, and western blotting. ADSCs were treated with sEV-LT and sEV-AT, respectively. Fluorescence confocal microscopy was used to investigate whether sEV-LT and sEV-AT could be taken by ADSCs. The proliferation and migration abilities and adipogenic differentiation assay of ADSCs were evaluated by CCK-8 assays, scratch test, and oil red O staining test, and the expression levels of adipogenic-related genes C/EBP-δ, PPARγ2, and Adiponectin in ADSCs were assessed by real-time quantitative PCR (RT-PCR). The sEV-LT and sEV-AT transplantation tubes were implanted subcutaneously in SD rats, and the neotissues were qualitatively and histologically evaluated at 2, 4, 8, and 12 weeks after transplantation. Hematoxylin and eosin (H&E) staining was subsequently used to observe and compare the adipogenesis and angiogenesis in neotissues, while immunohistochemistry was used to examine the expression and the distribution of C/EBP-α, PPARγ, Adiponectin, and CD31 at the 4th week.

RESULTS

The in vitro experiments showed that both sEV-LT and sEV-AT could be taken up by ADSCs via endocytosis. The scratch experiment and CCK-8 experiment showed that the migration area and proliferation number of ADSCs in sEV-LT group and sEV-AT group were significantly higher than those in the non-sEV group (p < 0.05). Compared with sEV-AT group, sEV-LT group had larger migration area and proliferation number of ADSCs (p < 0.05). Oil red O staining and RT-PCR experiments showed that, compared with the non-sEVs group, the lipid droplets and the mRNA expression levels of adipogenesis-related genes PPARγ2 and Adiponectin of ADSCs in sEV-LT group and sEV-AT group were significantly upregulated (p < 0.05); however, there was no statistical significance in the expression level of C/EBP-δ (p > 0.05). In addition, no significant difference in the amount of lipid droplets and adipogenesis-related genes between the sEV-LT groups and sEV-AT was seen (p > 0.05). At 2, 4, 8, and 12 weeks, the adipocyte area and the number of capillaries in neotissues in the sEV-LT groups and sEV-AT groups were significantly increased compared with the Matrigel group (p < 0.05); however, there was no dramatic difference between sEV-LT groups and sEV-AT groups (p > 0.05). At the 4th week, neotissues in the sEV-LT groups and sEV-AT groups all showed upregulated expression of C/EBP-α, PPARγ, Adiponectin, and CD31 protein, while neotissues in the Matrigel group only showed positive expression of CD31 protein.

CONCLUSIONS

This study demonstrated that sEV-LT exerted promotion effects on adipose tissue regeneration by accelerating the proliferation, migration, and adipogenic differentiation of ADSCs in vitro and recruiting adipocytes and promoting angiogenesis in vivo. The sEV-LT could serve as an alternative cell-free therapeutic strategy for generating adipose tissue, thus providing a promising application prospect in tissue engineering.

Functionalized Silica Star-Shaped Nanoparticles and Human Mesenchymal Stem Cells: An In Vitro Model

The biomedical translational applications of functionalized nanoparticles require comprehensive studies on their effect on human stem cells. Here, we have tested neat star-shaped mesoporous silica nanoparticles (s-MSN) and their chemically functionalized derivates; we examined nanoparticles (NPs) with similar dimensions but different surface chemistry, due to the amino groups grafted on silica nanoparticles (s-MSN-NH2), and gold nanoseeds chemically adsorbed on silica nanoparticles (s-MSN-Au). The different samples were dropped on glass coverslips to obtain a homogeneous deposition differing only for NPs' chemical functionalization and suitable for long-term culture of human Bone Marrow-Mesenchymal stem cells (hBM-MSCs) and Adipose stem cells (hASCs). Our model allowed us to demonstrate that hBM-MSCs and hASCs have comparable growth curves, viability, and canonical Vinculin Focal adhesion spots on functionalized s-MSN-NH2 and s-MSN-Au as on neat s-MSN and control systems, but also to show morphological changes on all NP types compared to the control counterparts. The new shape was stem-cell-specific and was maintained on all types of NPs. Compared to the other NPs, s-MSN-Au exerted a small genotoxic effect on both stem cell types, which, however, did not affect the stem cell behavior, likely due to a peculiar stem cell metabolic restoration response.

Chemically Defined Xeno- and Serum-Free Cell Culture Medium to Grow Human Adipose Stem Cells

Adipose tissue is an abundant source of stem cells. However, liposuction cannot yield cell quantities sufficient for direct applications in regenerative medicine. Therefore, the development of GMP-compliant ex vivo expansion protocols is required to ensure the production of a "cell drug" that is safe, reproducible, and cost-effective. Thus, we developed our own basal defined xeno- and serum-free cell culture medium (UrSuppe), specifically formulated to grow human adipose stem cells (hASCs). With this medium, we can directly culture the stromal vascular fraction (SVF) cells in defined cell culture conditions to obtain hASCs. Cells proliferate while remaining undifferentiated, as shown by Flow Cytometry (FACS), Quantitative Reverse Transcription PCR (RT-qPCR) assays, and their secretion products. Using the UrSuppe cell culture medium, maximum cell densities between 0.51 and 0.80 × 10⁵ cells/cm² (=2.55-4.00 × 10⁵ cells/mL) were obtained. As the expansion of hASCs represents only the first step in a cell therapeutic protocol or further basic research studies, we formulated two chemically defined media to differentiate the expanded hASCs in white or beige/brown adipocytes. These new media could help translate research projects into the clinical application of hASCs and study ex vivo the biology in healthy and dysfunctional states of adipocytes and their precursors. Following the cell culture system developers' practice and obvious reasons related to the formulas' patentability, the defined media's composition will not be disclosed in this study.

Development of a Biodegradable Microcarrier for the Cultivation of Human Adipose Stem Cells (hASCs) with a Defined Xeno- and Serum-Free Medium

Stirred single-use bioreactors in combination with microcarriers (MCs) have established themselves as a technology that has the potential to meet the demands of current and future cell therapeutic markets. However, most of the published processes have been performed using fetal bovine serum (FBS) containing cell culture medium and non-biocompatible MCs. This approach has two significant drawbacks: firstly, the inevitable potential risks associated with the use of FBS for clinical applications; secondly, non-biocompatible MCs have to be removed from the cell suspension before implantation, requiring a step that causes loss of viable cells and adds further costs and complications. This study aimed to develop a new platform based on a chemically defined xeno- and serum-free cell culture medium and biodegradable MC that can support the growth of human adipose stem cells (hASCs) while still preserving their undifferentiated status. A specific combination of components and manufacturing parameters resulted in a MC prototype, called “BR44”, which delivered the desired functionality. MC BR44 allows the hASCs to stick to its surface and grow in a chemically defined xeno- and serum-free medium (UrSuppe). Although the cells’ expansion rate was not as high as with a commercial non-biodegradable standard MC, those cultured on BR44 maintained a better undifferentiated status in both static and dynamic conditions than those cultured on traditional 2D surfaces.

The Crosstalk of Adipose-Derived Stem Cells (ADSC), Oxidative Stress, and Inflammation in Protective and Adaptive Responses

The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs is a major goal in repair medicine. Stem cells are classified by their potential to differentiate into functional cells. Compared with other sources, adipose-derived stem cells (ADSCs) have the advantage of being abundant and easy to obtain. ADSCs are considered to be tools for replacing, repairing, and regenerating dead or damaged cells. The capacity of ADSCs to maintain their properties depends on the balance of complex signals in their microenvironment. Their properties and the associated outcomes are in part regulated by reactive oxygen species, which mediate the oxidation-reduction state of cells as a secondary messenger. ADSC therapy has demonstrated beneficial effects, suggesting that secreted factors may provide protection. There is evidence that ADSCs secrete a number of cytokines, growth factors, and antioxidant factors into their microenvironment, thus regulating intracellular signaling pathways in neighboring cells. In this review, we introduce the roles of ADSCs in the protection of cells by modulating inflammation and immunity, and we develop their potential therapeutic properties.

Novel Nanocomposite PLA Films with Lignin/Zinc Oxide Hybrids: Design, Characterization, Interaction with Mesenchymal Stem Cells

Herein we present the production of novel nanocomposite films consisting of polylactic acid (PLA) polymer and the inclusion of nanoparticles of lignin (LNP), ZnO and hybrid ZnO@LNP (ZnO, 3.5% wt, ICP), characterized by similar regular shapes and different diameter distribution (30-70 nm and 100-150 nm, respectively). The obtained set of binary, ternary and quaternary systems were similar in surface wettability and morphology but different in the tensile performance: while the presence of LNP and ZnO in PLA caused a reduction of elastic modulus, stress and deformation at break, the inclusion of ZnO@LNP increased the stiffness and tensile strength (σb = 65.9 MPa and EYoung = 3030 MPa) with respect to neat PLA (σb = 37.4 MPa and EYoung = 2280 MPa). Neat and nanocomposite PLA-derived films were suitable for adult human bone marrow-mesenchymal stem cells and adipose stem cell cultures, as showed by their viability and behavior comparable to control conditions. Both stem cell types adhered to the films' surface by vinculin focal adhesion spots and responded to the films' mechanical properties by orchestrating the F-actin-filamin A interaction. Collectively, our results support the biomedical application of neat- and nanocomposite-PLA films and, based on the absence of toxicity in seeded stem cells, provide a proof of principle of their safety for food packaging purposes.

The Other Side of Alzheimer's Disease: Influence of Metabolic Disorder Features for Novel Diagnostic Biomarkers

Nowadays, the amyloid cascade hypothesis is the dominant model to explain Alzheimer's disease (AD) pathogenesis. By this hypothesis, the inherited genetic form of AD is discriminated from the sporadic form of AD (SAD) that accounts for 85-90% of total patients. The cause of SAD is still unclear, but several studies have shed light on the involvement of environmental factors and multiple susceptibility genes, such as Apolipoprotein E and other genetic risk factors, which are key mediators in different metabolic pathways (e.g., glucose metabolism, lipid metabolism, energetic metabolism, and inflammation). Furthermore, growing clinical evidence in AD patients highlighted the presence of affected systemic organs and blood similarly to the brain. Collectively, these findings revise the canonical understating of AD pathogenesis and suggest that AD has metabolic disorder features. This review will focus on AD as a metabolic disorder and highlight the contribution of this novel understanding on the identification of new biomarkers for improving an early AD diagnosis.

Histology of skeletal muscle reconstructed by means of the implantation of autologous adipose tissue: an experimental study

The purpose of this study was to determine the histological characteristics of a skeletal muscle reconstructed by means of the implantation of autologous adipose tissue following an experimentally-induced volumetric muscle loss. A cylindrical piece in the belly of the rat anterior tibial muscle was removed. In the hole, inguinal subcutaneous adipose tissue of the same rat was grafted. Animals were sacrificed 7, 14, 21, 28 and 60 days posttransplantation. Histological, histochemical, immunohistochemical and morphometric techniques were used. At all times analyzed, the regenerative muscle fibers formed from the edges of the muscle tissue showed histological, histochemical and immunohistochemical differences in comparison with the control group. These differences are related to delays in the maturation process and are related to problems in reinnervation and disorientation of muscle fibers. The stains for MyoD and desmin showed that some myoblasts and myotubes seem to derive from the transplanted adipose tissue. After 60 days, the transplant area was 20% occupied by fibrosis and by 80% skeletal muscle. However, the neo-muscle was chaotically organized showing muscle fiber disorientation and centronucleated fibers with irregular shape and size. Our results support the hypothesis that, at least from a morphological point of view, autologous adipose tissue transplantation favors reconstruction following a volumetric loss of skeletal muscle by combining the inherent regenerative response of the organ itself and the myogenic differentiation of the stem cells present in the adipose tissue. However, in our study, the formed neo-muscle exhibited histological differences in comparison with the normal skeletal muscle.

Stem cell therapy: old challenges and new solutions

Stem cell therapy (SCT), born as therapeutic revolution to replace pharmacological treatments, remains a hope and not yet an effective solution. Accordingly, stem cells cannot be conceivable as a "canonical" drug, because of their unique biological properties. A new reorientation in this field is emerging, based on a better understanding of stem cell biology and use of cutting-edge technologies and innovative disciplines. This will permit to solve the gaps, failures, and long-term needs, such as the retention, survival and integration of stem cells, by employing pharmacology, genetic manipulation, biological or material incorporation. Consequently, the clinical applicability of SCT for chronic human diseases will be extended, as well as its effectiveness and success, leading to long-awaited medical revolution. Here, some of these aspects are summarized, reviewing and discussing recent advances in this rapidly developing research field.

Hopes and Limits of Adipose-Derived Stem Cells (ADSCs) and Mesenchymal Stem Cells (MSCs) in Wound Healing

Adipose tissue derived stem cells (ADSCs) are mesenchymal stem cells identified within subcutaneous tissue at the base of the hair follicle (dermal papilla cells), in the dermal sheets (dermal sheet cells), in interfollicular dermis, and in the hypodermis tissue. These cells are expected to play a major role in regulating skin regeneration and aging-associated morphologic disgraces and structural deficits. ADSCs are known to proliferate and differentiate into skin cells to repair damaged or dead cells, but also act by an autocrine and paracrine pathway to activate cell regeneration and the healing process. During wound healing, ADSCs have a great ability in migration to be recruited rapidly into wounded sites added to their differentiation towards dermal fibroblasts (DF), endothelial cells, and keratinocytes. Additionally, ADSCs and DFs are the major sources of the extracellular matrix (ECM) proteins involved in maintaining skin structure and function. Their interactions with skin cells are involved in regulating skin homeostasis and during healing. The evidence suggests that their secretomes ensure: (i) The change in macrophages inflammatory phenotype implicated in the inflammatory phase, (ii) the formation of new blood vessels, thus promoting angiogenesis by increasing endothelial cell differentiation and cell migration, and (iii) the formation of granulation tissues, skin cells, and ECM production, whereby proliferation and remodeling phases occur. These characteristics would be beneficial to therapeutic strategies in wound healing and skin aging and have driven more insights in many clinical investigations. Additionally, it was recently presented as the tool key in the new free-cell therapy in regenerative medicine. Nevertheless, ADSCs fulfill the general accepted criteria for cell-based therapies, but still need further investigations into their efficiency, taking into consideration the host-environment and patient-associated factors.

Heart Failure and Adipose Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are considered a promising cell type for the treatment of heart failure (HF). In particular, MSCs in adipose tissue are being evaluated as an effective therapeutic tool. However, adipose MSCs are a major source of adipocyte generation and linked to obesity, which is an independent risk factor for HF. MSCs express all of the components of the renin-angiotensin system (RAS), which plays a pivotal role in the pathophysiology of HF. The local RAS also regulates MSC adipogenesis, indicating a connection between MSC-adipogenesis-obesity and HF. This review examines evidence of the complex relationship between HF and adipose MSCs and discusses how to explore this association for favorable therapeutic outcomes for HF.

Harnessing the Potential of Stem Cells for Disease Modeling: Progress and Promises

Ex vivo cell/tissue-based models are an essential step in the workflow of pathophysiology studies, assay development, disease modeling, drug discovery, and development of personalized therapeutic strategies. For these purposes, both scientific and pharmaceutical research have adopted ex vivo stem cell models because of their better predictive power. As matter of a fact, the advancing in isolation and in vitro expansion protocols for culturing autologous human stem cells, and the standardization of methods for generating patient-derived induced pluripotent stem cells has made feasible to generate and investigate human cellular disease models with even greater speed and efficiency. Furthermore, the potential of stem cells on generating more complex systems, such as scaffold-cell models, organoids, or organ-on-a-chip, allowed to overcome the limitations of the two-dimensional culture systems as well as to better mimic tissues structures and functions. Finally, the advent of genome-editing/gene therapy technologies had a great impact on the generation of more proficient stem cell-disease models and on establishing an effective therapeutic treatment. In this review, we discuss important breakthroughs of stem cell-based models highlighting current directions, advantages, and limitations and point out the need to combine experimental biology with computational tools able to describe complex biological systems and deliver results or predictions in the context of personalized medicine.

Pyridoxal-5'-Phosphate Promotes Immunomodulatory Function of Adipose-Derived Mesenchymal Stem Cells through Indoleamine 2,3-Dioxygenase-1 and TLR4/NF-κB Pathway

Adipose-derived mesenchymal stem cells (A-MSCs) are promising cellular therapies for the treatment of immune-mediated diseases. Non-gene editing technologies can improve the immune regulatory function of A-MSCs. Our preliminary experiments revealed that an active form of vitamin B6-pyridoxal-5'-phosphate (PLP)-plays an important role in regulating gene expression and cytokine secretion in A-MSCs in vivo. To further clarify the effect of PLP on receptors and cytokines related to the immune regulatory function of A-MSCs, a series of experiments were designed to verify the relationships between PLP and A-MSCs in vitro. Initially, A-MSCs were obtained, and cytokine secretion and the expression of IDO1, NF-κB, and Toll-like receptors in PLP-stimulated A-MSCs were evaluated. In addition, coculture was used to detect A-MSCs-mediated apoptosis of CD3⁺CD8⁺ T lymphocytes. These results showed that A-MSCs stimulated with PLP were highly proliferative, consistent with their pluripotent capacity. Further, the surface receptors TLR3, TLR4, IDO1, and NF-κB were upregulated, while TLR6 was downregulated. Concurrently, A-MSCs preconditioned with PLP had the greatest inhibitory effect on CD3⁺CD8⁺ T lymphocyte proliferation, indicating that PLP altered the immune regulatory function of A-MSCs through the regulation of TLRs and IDO1 expression.

Neurospheres Induced from Human Adipose-Derived Stem Cells as a New Source of Neural Progenitor Cells

Human adipose-derived stem cells are used in regenerative medicine for treating various diseases including osteoarthritis, degenerative arthritis, cartilage or tendon injury, etc. However, their use in neurological disorders is limited, probably due to the lack of a quick and efficient induction method of transforming these cells into neural stem or progenitor cells. In this study, we reported a highly efficient and simple method to induce adipose-derived stem cells into neural progenitor cells within 12 hours, using serum-free culture combined with a well-defined induction medium (epidermal growth factor 20 ng/ml and basic fibroblast growth factor, both at 20 ng/ml, with N2 and B27 supplements). These adipose-derived stem cell-derived neural progenitor cells grow as neurospheres, can self-renew to form secondary neurospheres, and can be induced to become neurons and glial cells. Real-time polymerase chain reaction showed significantly upregulated expression of neurogenic genes Sox2 and Nestin with a moderate increase in stemness gene expression. Raybio human growth factor analysis showed a significantly upregulated expression of multiple neurogenic and angiogenic cytokines such as brain-derived neurotrophic factor, glial cell line-derived neurotrophic growth factor, nerve growth factor, basic fibroblast growth factor and vascular endothelial growth factor etc. Therefore, adipose-derived stem cell-derived neurospheres can be a new source of neural progenitor cells and hold great potential for future cell replacement therapy for treatment of various refractory neurological diseases.