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

The potential of mesenchymal stem cells to induce immune tolerance to allogeneic transplants

Organ allograft transplantation is an effective treatment plan for patients with organ failure. Although the application of continuous immunosuppressants makes successful allograft survival possible, the patients' long-term survival rate and quality of life are not ideal. Therefore, it is necessary to find a new strategy to alleviate transplant rejection by developing therapies for permanent allograft acceptance. One promising approach is the application of tolerogenic mesenchymal stem cells (MSCs). Extensive research on MSCs has revealed that MSCs have potent differentiation potential and immunomodulatory properties. This review describes the molecular markers and functional properties of MSCs as well as the immunomodulatory mechanisms of MSCs in transplantation, focuses on the research progress in clinical trials of MSCs, and expounds on the future development prospects and possible limitations.

White adipose tissue-derived small extracellular vesicles: A new potential therapeutic reagent for accelerating diabetic wound healing

Small extracellular vesicles (sEVs) from adipose-derived stem cells (ADSCs) have gained great attention and have been widely used in cell-free therapies for treating diabetic non-healing wounds in recent years. However, further clinical application of ADSC-sEVs have been limited due to their unsolvable defects, including cumbersome extraction procedure, high cost, low yield, etc. Thus, we urgently need to find one therapeutic reagent that could not only accelerate diabetic wound healing as ADSC-sEVs but also overcome these shortcomings. As the extraction process of adipose tissue-derived sEVs (AT-sEVs) is quite simple and labor saving, we put our focus on the efficiencies of white adipose tissue-derived sEVs (WAT-sEVs) and brown adipose tissue-derived sEVs (BAT-sEVs) in diabetic wound repair. After successfully isolating WAT-sEVs and BAT-sEVs by ultracentrifugation, we thoroughly characterized them and compared their diabetic wound healing capabilities both in vitro and in vivo. According to our study, AT-sEVs possess similar competence in diabetic wound healing as compared with ADSC-sEVs. While the effect of BAT-sEVs is not as stable as WAT-sEVs and ADSC-sEVs, the repair efficiency is also slightly lower than the other two sEVs in some cases. In summary, we are the first to discover that WAT-sEVs show great potential in diabetic wound repair. With advantages that are specific to tissue-derived sEVs (Ti-sEVs) such as time- and cost-saving, high-yield, and simple isolation procedure, we believe WAT-sEVs could serve as a novel reliable cell-free therapy for clinical diabetic wound treatment.

Transplantation of adipose derived stem cells in diabetes mellitus; limitations and achievements

Objectives

Diabetes mellitus (DM) is a complex metabolic disease that results from impaired insulin secreting pancreatic β-cells or insulin resistance. Although available medications help control the disease, patients suffer from its complications. Therefore, finding effective therapeutic approaches to treat DM is a priority. Adipose Derived Stem Cells (ADSCs) based therapy is a promising strategy in various regenerative medicine applications, but its systematic translational use is still somewhat out of reach. This review is aimed at clarifying achievements as well as challenges facing the application of ADSCs for the treatment of DM, with a special focus on the mechanisms involved.

Methods

Literature searches were carried out on "Scopus", "PubMed" and "Google Scholar" up to September 2022 to find relevant articles in the English language for the scope of this review.

Results

Recent evidence showed a significant role of ADSC therapies in DM by ameliorating insulin resistance and hyperglycemia, regulating hepatic glucose metabolism, promoting β cell function and regeneration, and functioning as a gene delivery tool. In addition, ADSCs could improve diabetic wound healing by promoting collagen deposition, inhibiting inflammation, and enhancing angiogenesis.

Conclusion

Overall, this literature review revealed the great clinical implications of ADSCs for translating into the clinical setting for the treatment of diabetes. However, further large-scale and controlled studies are needed to overcome challenges and confirm the safety and optimal therapeutic scheme before daily clinical application.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01280-8.

Adipose stem cells in tissue regeneration and repair: From bench to bedside

ADSCs are a large number of mesenchymal stem cells in Adipose tissue, which can be applied to tissue engineering. ADSCs have the potential of multi-directional differentiation, and can differentiate into bone tissue, cardiac tissue, urothelial cells, skin tissue, etc. Compared with other mesenchymal stem cells, ADSCs have a multitude of promising advantages, such as abundant number, accessibility in cell culture, stable function, and less immune rejection. There are two main methods to use ADSCs for tissue repair and regeneration. One is to implant the "ADSCs-scaffold composite" into the injured site to promote tissue regeneration. The other is cell-free therapy: using ADSC-exos or ADSC-CM alone to release a large number of miRNAs, cytokines and other bioactive substances to promote tissue regeneration. The tissue regeneration potential of ADSCs is regulated by a variety of cytokines, signaling molecules, and external environment. The differentiation of ADSCs into different tissues is also induced by growth factors, ions, hormones, scaffold materials, physical stimulation, and other factors. The specific mechanisms are complex, and most of the signaling pathways need to be further explored. This article reviews and summarizes the mechanism and clinical application of ADSCs in tissue injury repair so far, and puts forward further problems that need to be solved in this field, hoping to provide directions for further research in this field.

Regeneration and anti-inflammatory effects of stem cells and their extracellular vesicles in gynecological diseases

There are many gynecological diseases, among which breast cancer (BC), cervical cancer (CC), endometriosis (EMs), and polycystic ovary syndrome (PCOS) are common and difficult to cure. Stem cells (SCs) are a focus of regenerative medicine. They are commonly used to treat organ damage and difficult diseases because of their potential for self-renewal and multidirectional differentiation. SCs are also commonly used for difficult-to-treat gynecological diseases because of their strong directional differentiation ability with unlimited possibilities, their tendency to adhere to the diseased tissue site, and their use as carriers for drug delivery. SCs can produce exosomes in a paracrine manner. Exosomes can be produced in large quantities and have the advantage of easy storage. Their safety and efficacy are superior to those of SCs, which have considerable potential in gynecological treatment, such as inhibiting endometrial senescence, promoting vascular reconstruction, and improving anti-inflammatory and immune functions. In this paper, we review the mechanisms of the regenerative and anti-inflammatory capacity of SCs and exosomes in incurable gynecological diseases and the current progress in their application in genetic engineering to provide a foundation for further research.

Aptamer-functionalized hydrogels promote bone healing by selectively recruiting endogenous bone marrow mesenchymal stem cells

Bone regeneration heavily relies on bone marrow mesenchymal stem cells (BMSCs). However, recruiting endogenous BMSCs for in situ bone regeneration remains challenging. In this study, we developed a novel BMSC-aptamer (BMSC-apt) functionalized hydrogel (BMSC-aptgel) and evaluated its functions in recruiting BMSCs and promoting bone regeneration. The functional hydrogels were synthesized between maleimide-terminated 4-arm polyethylene glycols (PEG) and thiol-flanked PEG crosslinker, allowing rapid in situ gel formation. The aldehyde group-modified BMSC-apt was covalently bonded to a thiol-flanked PEG crosslinker to produce high-density aptamer coverage on the hydrogel surface. In vitro and in vivo studies demonstrated that the BMSC-aptgel significantly increased BMSC recruitment, migration, osteogenic differentiation, and biocompatibility. In vivo fluorescence tomography imaging demonstrated that functionalized hydrogels effectively recruited DiR-labeled BMSCs at the fracture site. Consequently, a mouse femur fracture model significantly enhanced new bone formation and mineralization. The aggregated BMSCs stimulated bone regeneration by balancing osteogenic and osteoclastic activities and reduced the local inflammatory response via paracrine effects. This study's findings suggest that the BMSC-aptgel can be a promising and effective strategy for promoting in situ bone regeneration.

Preconditioning with Substance P Restores Therapeutic Efficacy of Aged ADSC by Elevating TNFR2 and Paracrine Potential

Aging leads to a decline in stem cell activity by reducing the repopulation rate and paracrine potential, ultimately diminishing efficacy in vivo. TNF-α can exert inflammatory and cell death actions via Erk by binding to TNFR-1, and survival and tissue repair actions via Akt by binding to TNFR-2. Aged cells are reported to have insufficient expression of TNFR-2, indicating that aged adipose-derived stem cells (ADSCs-E) lack the ability for cell survival and immune control compared to young ADSCs (ADSCs-Y). This study aims to assess the preconditioning effect of SP on the response of ADSCs-E to inflammation. ADSCs-E were treated with SP and then exposed to a high dose of TNF-α for 24 h. Consequently, ADSC-E exhibited weaker viability and lower TNFR2 levels compared to ADSC-Y. In response to TNF-α, the difference in TNFR2 expression became more pronounced in ADSC-E and ADSC-Y. Moreover, ADSC-E showed a severe deficiency in proliferation and paracrine activity. However, preconditioning with SP significantly enhanced the viability of ADSCs-E and also restored TNFR2 expression and paracrine potential, similar to ADSC-Y under inflammatory conditions. Our findings support the idea that preconditioning with SP has the potential to restore the cellular function of senescent stem cells before transplantation.

Single-cell analysis of human dermal fibroblasts isolated from a single male donor over 35 years

The aim of this study is to examine the effects of ageing on dermal fibroblast heterogeneity based on samples obtained from the same donor. We used a dermal fibroblast lineage (named ASF-4 cell lines) isolated from the inner side of the upper arm of a healthy male donor over a 35-year period, beginning at 36 years of age. Because clonal analysis of ASF-4 cell lines demonstrated a donor age-dependent loss of proliferative capacity and acquisition of senescent traits at the single-cell level, cultured cells frozen at passage 10 at ages 36 and 72 years were subjected to single-cell RNA sequencing. Transcriptome analysis revealed an increase in senescent fibroblasts and downregulation of genes associated with extracellular matrix remodelling with ageing. In addition, two putative differentiation pathways, with one endpoint consisting of senescent fibroblasts and the other without, were speculated using a pseudo-time analysis. Knockdown of the characteristic gene of the non-senescent fibroblast cluster endpoint, EFEMP2, accelerated cellular senescence. This was also confirmed in two other normal human dermal fibroblast cell lines. The detection of a common cellular senescence-related gene from single-donor analysis is notable. This study provides new insights into the behaviour of dermal fibroblasts during skin ageing.

Application of mesenchymal stem cells in regenerative medicine: A new approach in modern medical science

Mesenchymal Stem Cells (MSCs) are non-hematopoietic and multipotent stem cells, which have been considered in regenerative medicine. These cells are easily separated from different sources, such as bone marrow (BM), umbilical cord (UC), adipose tissue (AT), and etc. MSCs have the differentiation capability into chondrocytes, osteocytes, and adipocytes; This differentiation potential along with the paracrine properties have made them a key choice for tissue repair. MSCs also have various advantages over other stem cells, which is why they have been extensively studied in recent years. The effectiveness of MSCs-based therapies depend on several factors, including differentiation status at the time of use, concentration per injection, delivery method, the used vehicle, and the nature and extent of the damage. Although, MSCs have emerged promising sources for regenerative medicine, there are potential risks regarding their safety in their clinical use, including tumorigenesis, lack of availability, aging, and sensitivity to toxic environments. In this study, we aimed to discuss how MSCs may be useful in treating defects and diseases. To this aim, we will review recent advances of MSCs action mechanisms in regenerative medicine, as well as the most recent clinical trials. We will also have a brief overview of MSCs resources, differences between their sources, culture conditions, extraction methods, and clinical application of MSCs in various fields of regenerative medicine.

Comprehensive Analysis of Local Anesthetics Affecting Adipose Stem Cells In Vitro

BACKGROUND

Adipose stem cells (ASCs) hold a great regenerative capacity because of their differentiation capability and their secretory activity. Thus, ASC survival is of great significance during perioperative harvesting. Various local anesthetics are commonly applied during fat grafting procedures. These substances are known to impair cellular viability, which would affect graft survival and final outcomes, but the exact extent of their impact on ASC biology is unknown.

METHODS

The authors analyzed the short- and long-term effects of lidocaine, mepivacaine, ropivacaine, and bupivacaine at increasing concentrations (0.1 to 10 mM) on primary human ASC proliferation and metabolic activity. Trilinear differentiation was assessed by oil red O stain (adipogenesis), safranin O (chondrogenesis), and cresolphthalein (osteogenesis) labeling. In supernatants, cytokine [interleukin (IL)-6/IL-8, vascular endothelial growth factor, hepatocyte growth factor] secretion was analyzed by enzyme-linked immunosorbent assay.

RESULTS

Bupivacaine at greater than 100 µM demonstrated the strongest anti proliferative effects, whereas lidocaine and ropivacaine did not affect cell numbers. Mepivacaine evoked reciprocal results regarding cell count at greater than 1 mM. Each compound impaired trilinear differentiation. Secretion of hepatocyte growth factor and IL-8 was reduced significantly by local anesthetic exposure; levels were restored after substances were washed out.

CONCLUSIONS

In vitro data show that lidocaine, mepivacaine, and ropivacaine could be applied at concentrations of 1 to 10 mM without affecting ASC survival. In contrast, bupivacaine at concentrations greater than 100 µM should be administered with great caution. The differentiation of ASCs and the ASC's secretome might already be decreased by each local anesthetic at 1 mM.

CLINICAL RELEVANCE STATEMENT

The authors' experimental data can be of great significance to the clinical practice, as local anesthetics are routinely administered during liposuction as a tumescent anesthesia adjunct.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Application of 3D- printed hydrogels in wound healing and regenerative medicine

Hydrogels are three-dimensional polymer networks with hydrophilic properties. The modifiable properties of hydrogels and the structure resembling living tissue allow their versatile application. Therefore, increasing attention is focused on the use of hydrogels as bioinks for three-dimensional (3D) printing in tissue engineering. Bioprinting involves the fabrication of complex structures from several types of materials, cells, and bioactive compounds. Stem cells (SC), such as mesenchymal stromal cells (MSCs) are frequently employed in 3D constructs. SCs have desirable biological properties such as the ability to differentiate into various types of tissue and high proliferative capacity. Encapsulating SCs in 3D hydrogel constructs enhances their reparative abilities and improves the likelihood of reaching target tissues. In addition, created constructs can simulate the tissue environment and mimic biological signals. Importantly, the immunogenicity of scaffolds is minimized through the use of patient-specific cells and the biocompatibility and biodegradability of the employed biopolymers. Regenerative medicine is taking advantage of the aforementioned capabilities in regenerating various tissues- muscle, bones, nerves, heart, skin, and cartilage.

Transglutaminase 2 Prevents Premature Senescence and Promotes Osteoblastic Differentiation of Mesenchymal Stem Cells through NRF2 Activation

Transglutaminase 2 (TG2) is a multifunctional enzyme that exhibits transamidase, GTPase, kinase, and protein disulfide isomerase (PDI) activities. Of these, transamidase-mediated modification of proteins regulates apoptosis, differentiation, inflammation, and fibrosis. TG2 is highly expressed in mesenchymal stem cells (MSCs) compared with differentiated cells, suggesting a role of TG2 specific for MSC characteristics. In this study, we report a new function of TG2 in the regulation of MSC redox homeostasis. During in vitro MSC expansion, TG2 is required for cell proliferation and self-renewal by preventing premature senescence but has no effect on the expression of surface antigens and oxidative stress-induced cell death. Moreover, induction of differentiation upregulates TG2 that promotes osteoblastic differentiation. Molecular analyses revealed that TG2 mediates tert-butylhydroquinone, but not sulforaphane, -induced nuclear factor erythroid 2-related factor 2 (NRF2) activation in a transamidase activity-independent manner. Differences in the mechanism of action between two NRF2 activators suggest that PDI activity of TG2 may be implicated in the stabilization of NRF2. The role of TG2 in the regulation of antioxidant response was further supported by transcriptomic analysis of MSC. These results indicate that TG2 is a critical enzyme in eliciting antioxidant response in MSC through NRF2 activation, providing a target for optimizing MSC manufacturing processes to prevent premature senescence.

The HIFIA/LINC02913/IGF1R axis promotes the cell function of adipose-derived mesenchymal stem cells under hypoxia via activating the PI3K/AKT pathway

OBJECTIVE

Promoting angiogenesis is crucial for tissue repair. Adipose-derived mesenchymal stem cells (ADSCs) are endowed with the ability of paracrine secretion of various angiogenic cytokines and the differentiation potential into endothelium-like cells to directly participate in angiogenesis. ADSCs are key seed cells for promoting angiogenesis in regenerative medicine and tissue engineering. This study aimed to explore the role and mechanism of C9orf106 (LINC02913) in the angiogenesis of ADSCs.

METHODS

The microarray dataset GSE12884 was analyzed to identify the differentially expressed lncRNAs in ADSCs under normoxia and hypoxia. The expression of the key genes was detected using qRT-PCR, western blot assay (western blot), and immunofluorescence (IF) staining. The adipogenic ability and tube formation ability of ADSCs was detected using oil red O staining and tube formation assay, respectively. The regulatory relationship between hypoxia-inducible factor-1alpha (HIF1A) and LINC02913 was verified using chromatin immunoprecipitation (ChIP) assay and dual-luciferase reporter gene assay. A skin wound healing nude mice model was established. Hematoxylin and eosin (H&E) staining was applied to detect pathological skin damage. Immunohistochemistry (IHC) staining was used to determine the level of CD31 in skin tissues.

RESULTS

LINC02913 expression was decreased in ADSCs under hypoxia; LINC02913 overexpression inhibited the proliferation, adipogenic ability, endothelial differentiation ability, and tube formation ability of ADSCs. ChIP assay and dual-luciferase reporter gene assay results showed that HIF1A could directly bind to the LINC02913 promoter region to inhibit its transcription. Through RNAact prediction and analysis of the correlation with LINC02913 expression, it was found that IGF1R may directly interact with LINCO02913. The HIF1A/LINC02913/IGF1R axis could activate the PI3K/AKT pathway to promote the biological function of ADSCs. Hypoxia-ADSCs significantly promoted vascularization in the wounded skin. The regulatory effect of LINC02913/IGF1R axis on hypoxia-ADSCs treated skin wound healing were verified.

CONCLUSION

The HIF1A/LINC02913/IGF1R axis promoted the proliferation, adipogenic ability, and tube formation ability of ADSCs under hypoxia via activating the PI3K/AKT pathway.

Exosomal MicroRNAs: An Emerging Important Regulator in Acute Lung Injury

Acute lung injury (ALI) is a clinically life-threatening form of respiratory failure with a mortality of 30%-40%. Acute respiratory distress syndrome is the aggravated form of ALI. Exosomes are extracellular lipid vesicles ubiquitous in human biofluids with a diameter of 30-150 nm. They can serve as carriers to convey their internal cargo, particularly microRNA (miRNA), to the target cells involved in cellular communication. In disease states, the quantities of exosomes and the cargo generated by cells are altered. These exosomes subsequently function as autocrine or paracrine signals to nearby or distant cells, regulating various pathogenic processes. Moreover, exosomal miRNAs from multiple stem cells can provide therapeutic value for ALI by regulating different signaling pathways. In addition, changes in exosomal miRNAs of biofluids can serve as biomarkers for the early diagnosis of ALI. This study aimed to review the role of exosomal miRNAs produced by different sources participating in various pathological processes of ALI and explore their potential significance in the treatment and diagnosis.

Microneedle-based cell delivery and cell sampling for biomedical applications

Cell-based therapeutics are novel therapeutic strategies that can potentially treat many presently incurable diseases through novel mechanisms of action. Cell therapies may benefit from the ease, safety, and efficacy of administering therapeutic cells. Despite considerable recent technological and biological advances, several barriers remain to the clinical translation and commercialization of cell-based therapies, including low patient compliance, personal handling inconvenience, poor biosafety, and limited biocompatibility. Microneedles (MNs) are emerging as a promising biomedical device option for improved cell delivery with little invasion, pain-free administration, and simplicity of disposal. MNs have shown considerable promise in treating a wide range of diseases and present the potential to improve cell-based therapies. In this review, we first summarized the latest advances in the various types of MNs developed for cell delivery and cell sampling. Emphasis was given to the design and fabrication of various types of MNs based on their structures and materials. Then we focus on the recent biomedical applications status of MNs-mediated cell delivery and sampling, including tissue repair (wound healing, heart repair, and endothelial repair), cancer treatment, diabetes therapy, cell sampling, and other applications. Finally, the current status of clinical application, potential perspectives, and the challenges for clinical translation are also highlighted.

Adipose-Derived Mesenchymal Stem Cell-Derived Exosomes Biopotentiated Extracellular Matrix Hydrogels Accelerate Diabetic Wound Healing and Skin Regeneration

Wound healing is an urgent clinical challenge, particularly in the case of chronic wounds. Traditional approaches to wound healing have limited therapeutic efficacy due to lengthy healing times, risk of immune rejection, and susceptibility to infection. Recently, adipose-derived mesenchymal stem cell-derived exosomes (ADSC-exos) have emerged as a promising modality for tissue regeneration and wound repair. In this study, the development of a novel extracellular matrix hydrogel@exosomes (ECM@exo) is reported, which entails incorporation of ADSC-exos into an extracellular matrix hydrogel (ECM hydrogel). This solution forms a hydrogel at physiological temperature (≈37 °C) upon local injection into the wound site. ECM@exo enables sustained release of ADSC-exos from the ECM hydrogel, which maintains high local concentrations at the wound site. The ECM hydrogel displays good biocompatibility and biodegradability. The in vivo and in vitro results demonstrate that ECM@exo treatment effectively reduces inflammation and promotes angiogenesis, collagen deposition, cell proliferation, and migration, thereby accelerating the wound healing process. Overall, this innovative therapeutic approach offers a new avenue for wound healing via a biological hydrogel with controlled exosome release.

Advancements in mesenchymal stem cell therapy for liver cirrhosis: Unveiling origins, treatment mechanisms, and current research frontiers

Chronic liver disease inevitably progresses to liver cirrhosis, significantly compromising patients' overall survival and quality of life. However, a glimmer of hope emerges with the emergence of mesenchymal stem cells, possessing remarkable abilities for self-renewal, differentiation, and immunomodulation. Leveraging their potential, MSCs have become a focal point in both basic and clinical trials, offering a promising therapeutic avenue to impede fibrosis progression and enhance the life expectancy of individuals battling hepatic cirrhosis. This comprehensive review serves to shed light on the origin of MSCs, the intricate mechanisms underlying cirrhosis treatment, and the cutting-edge advancements in basic and clinical research surrounding MSC-based therapies for liver cirrhosis patients.

Hydrolytic hydrogels tune mesenchymal stem cell persistence and immunomodulation for enhanced diabetic cutaneous wound healing

Diabetes is associated with an altered global inflammatory state with impaired wound healing. Mesenchymal stem/stromal cells (MSC) are being explored for treatment of diabetic cutaneous wounds due to their regenerative properties. These cells are commonly delivered by injection, but the need to prolong the retention of MSC at sites of injury has spurred the development of biomaterial-based MSC delivery vehicles. However, controlling biomaterial degradation rates in vivo remains a therapeutic-limiting challenge. Here, we utilize hydrolytically degradable ester linkages to engineer synthetic hydrogels with tunable in vivo degradation kinetics for temporally controlled delivery of MSC. In vivo hydrogel degradation rate can be controlled by altering the ratio of ester to amide linkages in the hydrogel macromers. These hydrolytic hydrogels degrade at rates that enable unencumbered cutaneous wound healing, while enhancing the local persistence MSC compared to widely used protease-degradable hydrogels. Furthermore, hydrogel-based delivery of MSC modulates local immune responses and enhances cutaneous wound repair in diabetic mice. This study introduces a simple strategy for engineering tunable degradation modalities into synthetic biomaterials, overcoming a key barrier to their use as cell delivery vehicles.

Perspectives on the Current State of Bioprinted Skin Substitutes for Wound Healing

Human skin is particularly vulnerable to external damaging influences such as irradiation, extreme temperatures, chemical trauma, and certain systemic diseases, which reduce the skin's capacity for regeneration and restoration and can possibly lead to large-scale skin defects. To restore skin continuity in severe cases, surgical interventions such as the transplantation of autologous tissue are needed. Nevertheless, the coverage of larger skin defects caused by severe third-grade burns or extensive irradiation therapy is limited due to the depletion of uninjured autologous tissue. In such cases, many of the patient's epidermal cells can become available using biofabricated skin grafts, thereby restoring the skin's vital functions. Given the limited availability of autologous skin grafts for restoring integrity in large-scale defects, using bioprinted constructs as skin graft substitutes could offer an encouraging therapeutic alternative to conventional therapies for large-scale wounds, such as the transplantation of autologous tissue. Using layer-by-layer aggregation or volumetric bioprinting, inkjet bioprinting, laser-assisted bioprinting, or extrusion-based bioprinting, skin cells are deposited in a desired pattern. The resulting constructs may be used as skin graft substitutes to accelerate wound healing and reconstitute the physiological functions of the skin. In this review, we aimed to elucidate the current state of bioprinting within the context of skin tissue engineering and introduce and discuss different bioprinting techniques, possible approaches and materials, commonly used cell types, and strategies for graft vascularization for the production of bioprinted constructs for use as skin graft substitutes.

Cell-free therapy based on extracellular vesicles: a promising therapeutic strategy for peripheral nerve injury

Peripheral nerve injury (PNI) is one of the public health concerns that can result in a loss of sensory or motor function in the areas in which injured and non-injured nerves come together. Up until now, there has been no optimized therapy for complete nerve regeneration after PNI. Exosome-based therapies are an emerging and effective therapeutic strategy for promoting nerve regeneration and functional recovery. Exosomes, as natural extracellular vesicles, contain bioactive molecules for intracellular communications and nervous tissue function, which could overcome the challenges of cell-based therapies. Furthermore, the bioactivity and ability of exosomes to deliver various types of agents, such as proteins and microRNA, have made exosomes a potential approach for neurotherapeutics. However, the type of cell origin, dosage, and targeted delivery of exosomes still pose challenges for the clinical translation of exosome therapeutics. In this review, we have focused on Schwann cell and mesenchymal stem cell (MSC)-derived exosomes in nerve tissue regeneration. Also, we expressed the current understanding of MSC-derived exosomes related to nerve regeneration and provided insights for developing a cell-free MSC therapeutic strategy for nerve injury.

A Supportive Role of Mesenchymal Stem Cells on Insulin-Producing Langerhans Islets with a Specific Emphasis on The Secretome

Type 1 Diabetes (T1D) is a chronic autoimmune disease characterized by a gradual destruction of insulin-producing β-cells in the endocrine pancreas due to innate and specific immune responses, leading to impaired glucose homeostasis. T1D patients usually require regular insulin injections after meals to maintain normal serum glucose levels. In severe cases, pancreas or Langerhans islet transplantation can assist in reaching a sufficient β-mass to normalize glucose homeostasis. The latter procedure is limited because of low donor availability, high islet loss, and immune rejection. There is still a need to develop new technologies to improve islet survival and implantation and to keep the islets functional. Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells with high plasticity that can support human pancreatic islet function both in vitro and in vivo and islet co-transplantation with MSCs is more effective than islet transplantation alone in attenuating diabetes progression. The beneficial effect of MSCs on islet function is due to a combined effect on angiogenesis, suppression of immune responses, and secretion of growth factors essential for islet survival and function. In this review, various aspects of MSCs related to islet function and diabetes are described.

Looking into the Skin in Health and Disease: From Microscopy Imaging Techniques to Molecular Analysis

The skin is a complex organ that includes a wide variety of tissue types with different embryological origins [...].

Low-glucose culture environment can enhance the wound healing capability of diabetic adipose-derived stem cells

BACKGROUND

Application of autologous adipose-derived stem cells (ASC) for diabetic chronic wounds has become an emerging treatment option. However, ASCs from diabetic individuals showed impaired cell function and suboptimal wound healing effects. We proposed that adopting a low-glucose level in the culture medium for diabetic ASCs may restore their pro-healing capabilities.

METHODS

ASCs from diabetic humans and mice were retrieved and cultured in high-glucose (HG, 4.5 g/L) or low-glucose (LG, 1.0 g/L) conditions. Cell characteristics and functions were investigated in vitro. Moreover, we applied diabetic murine ASCs cultured in HG or LG condition to a wound healing model in diabetic mice to compare their healing capabilities in vivo.

RESULTS

Human ASCs exhibited decreased cell proliferation and migration with enhanced senescence when cultured in HG condition in vitro. Similar findings were noted in ASCs derived from diabetic mice. The inferior cellular functions could be partially recovered when they were cultured in LG condition. In the animal study, wounds healed faster when treated with HG- or LG-cultured diabetic ASCs relative to the control group. Moreover, higher collagen density, more angiogenesis and cellular retention of applied ASCs were found in wound tissues treated with diabetic ASCs cultured in LG condition.

CONCLUSIONS

In line with the literature, our study showed that a diabetic milieu exerts an adverse effect on ASCs. Adopting LG culture condition is a simple and effective approach to enhance the wound healing capabilities of diabetic ASCs, which is valuable for the clinical application of autologous ASCs from diabetic patients.

Chronic Wound Management: From Gauze to Homologous Cellular Matrix

BACKGROUND

Chronic wounds are a significant health problem with devastating consequences for patients' physical, social, and mental health, increasing healthcare systems' costs. Their prolonged healing times, economic burden, diminished quality of life, increased infection risk, and impact on patients' mobility and functionality make them a major concern for healthcare professionals.

PURPOSE

This review offers a multi-perspective analysis of the medical literature focusing on chronic wound management.

METHODS USED

We evaluated 48 articles from the last 21 years registered in the MEDLINE and Global Health databases. The articles included in our study had a minimum of 20 citations, patients > 18 years old, and focused on chronic, complex, and hard-to-heal wounds. Extracted data were summarized into a narrative synthesis using the same health-related quality of life instrument.

RESULTS

We evaluated the efficacy of existing wound care therapies from classical methods to modern concepts, and wound care products to regenerative medicine that uses a patient's pluripotent stem cells and growth factors. Regenerative medicine and stem cell therapies, biologic dressings and scaffolds, negative pressure wound therapy (NPWT), electrical stimulation, topical growth factors and cytokines, hyperbaric oxygen therapy (HBOT), advanced wound dressings, artificial intelligence (AI), and digital wound management are all part of the new arsenal of wound healing.

CONCLUSION

Periodic medical evaluation and proper use of modern wound care therapies, including the use of plasma-derived products [such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF)] combined with proper systemic support (adequate protein levels, blood sugar, vitamins involved in tissue regeneration, etc.) are the key to a faster wound healing, and, with the help of AI, can reach the fastest healing rate possible.

The Combination of Stromal Vascular Fraction Cells and Platelet-Rich Plasma Increases Fibroblast Growth Factor 7 and Promotes Angiogenesis in Full Thickness Burn Injury: Rat Experimental Study

Our previous study on how the combination of stromal vascular fraction cells (SVFs) and platelet-rich plasma (PRP) affect deep dermal burn healing showed promising results. In this study, we assessed the effect on full-thickness burns by evaluating FGF7 serum level and capillary count. Forty-eight Wistar rats were divided into four major groups: (1) locally injected with combined SVFs and PRP; (2) topically applied Vaseline; (3) locally injected with placebo; (4) and rats without burns. These groups were divided further into smaller groups based on the day of euthanasia (8th hour, 4th day, 7th day, 14th day, and 21st day). FGF7 serum level was measured using ELISA, and capillaries were counted using a microscope. A one-way ANOVA test, post hoc, and regression tests were used. On day 4, both FGF7 and capillary counts showed significant differences between groups (p=0.000 and 0.048, respectively). On day 7, only FGF7 result showed a significant difference (p=0.000). On day 14, FGF7 and capillary counts showed significant differences (p=0.000, 0.018 respectively). The SVFs and PRP-treated groups showed superior results compared to other groups. The injection of combined SVFs and PRP increased FGF7 and capillary counts.

Effect of stem cell secretome in skin rejuvenation: a narrative review

PURPOSE

Cutaneous aging is an inevitable biological process that develops over time due to cumulative cellular and molecular changes caused by exposure to intrinsic (chronological aging) and extrinsic (photo-aging) factors on the skin. Skin aging is characterized by a decline in the body's capability to sustain senescence, dermal cell apoptosis, and homeostasis. Stem cell secretions (secretome) are defined as the total set of dynamically overlapping paracrine soluble growth factors, cytokines, chemokines, angiogenic factors, extracellular matrix proteins, and antimicrobial peptides known to be responsible for tissue rejuvenation, regeneration, homeostasis, and immunomodulation.

METHODS

In this review, we summarized the molecular and regulatory mechanism of the secretome in preventing the skin aging process, as well as its capacity in inducing skin rejuvenation. Furthermore, we illustrated secretome efficiency as an anti-aging therapeutic strategy based on in vitro and in vivo published studies.

RESULTS

In all reviewed publications, the secretome has been proven to be the most effective treatment for aged skin, capable of reversing the aging process through the action of cytokines, growth factors, and collagen, which are its primary components. The reported mechanism of action involves modulating the signaling pathways of aging and replenishing the skin with collagen, fibronectin, and elastin, ultimately resulting in skin renewal and rejuvenation.

CONCLUSION

In conclusion, compared to available treatments, the secretome shows great promise as an anti-aging therapy.

The Effects of Tissue Healing Factors in Wound Repair Involving Absorbable Meshes: A Narrative Review

Wound healing is a complex and meticulously orchestrated process involving multiple phases and cellular interactions. This narrative review explores the intricate mechanisms behind wound healing, emphasizing the significance of cellular processes and molecular factors. The phases of wound healing are discussed, focusing on the roles of immune cells, growth factors, and extracellular matrix components. Cellular shape alterations driven by cytoskeletal modulation and the influence of the 'Formin' protein family are highlighted for their impact on wound healing processes. This review delves into the use of absorbable meshes in wound repair, discussing their categories and applications in different surgical scenarios. Interleukins (IL-2 and IL-6), CD31, CD34, platelet rich plasma (PRP), and adipose tissue-derived mesenchymal stem cells (ADSCs) are discussed in their respective roles in wound healing. The interactions between these factors and their potential synergies with absorbable meshes are explored, shedding light on how these combinations might enhance the healing process. Recent advances and challenges in the field are also presented, including insights into mesh integration, biocompatibility, infection prevention, and postoperative complications. This review underscores the importance of patient-specific factors and surgical techniques in optimizing mesh placement and healing outcomes. As wound healing remains a dynamic field, this narrative review provides a comprehensive overview of the current understanding and potential avenues for future research and clinical applications.

The stereological, immunohistological, and gene expression studies in an infected ischemic wound in diabetic rats treated by human adipose-derived stem cells and photobiomodulation

We investigated the impacts of photobiomodulation (PBM) and human allogeneic adipose-derived stem cells (ha-ADS) together and or alone applications on the stereological parameters, immunohistochemical characterizing of M1 and M2 macrophages, and mRNA levels of hypoxia-inducible factor (HIF-1α), basic fibroblast growth factor (bFGF), vascular endothelial growth factor-A (VEGF-A) and stromal cell-derived factor-1α (SDF-1α) on inflammation (day 4) and proliferation phases (day 8) of repairing tissues in an infected delayed healing and ischemic wound model (IDHIWM) in type 1 diabetic (DM1) rats. DM1 was created in 48 rats and an IDHIWM was made in all of them, and they were distributed into 4 groups. Group1 = control rats with no treatment. Group2 = rats received (10 × 100000 ha-ADS). Group3 = rats exposed to PBM (890 nm, 80 Hz, 3.46 J/cm2). Group4 = rats received both PBM and ha-ADS. On day 8, there were significantly higher neutrophils in the control group than in other groups (p < 0.01). There were substantially higher macrophages in the PBM + ha-ADS group than in other groups on days 4 and 8 (p < 0.001). Granulation tissue volume, on both days 4 and 8, was meaningfully greater in all treatment groups than in the control group (all, p = 0.000). Results of M1 and M2 macrophage counts of repairing tissue in the entire treatment groups were considered preferable to those in the control group (p < 0.05). Regarding stereological and macrophage phenotyping, the results of the PBM + ha-ADS group were better than the ha-ADS and PBM groups. Results of the tested gene expression of repairing tissue on inflammation and proliferation steps in PBM and PBM + ha-ADS groups were meaningfully better than the control and ha-ADS groups (p < 0.05). We showed that PBM, ha-ADS, and PBM plus ha-ADS, hastened the proliferation step of healing in an IDHIWM in rats with DM1 by regulation of the inflammatory reaction, macrophage phenotyping, and augmented granulation tissue formation. In addition PBM and PBM plus ha-ADS protocols hastened and increased mRNA levels of HIF-1α, bFGF, SDF-1α, and VEGF-A. Totally, in terms of stereological and immuno-histological tests, and also gene expression HIF-1α and VEGF-A, the results of PBM + ha-ADS were superior (additive) to PBM, and ha-ADS alone treatments.

Adipose-derived mesenchymal stem cells-sourced exosomal microRNA-7846-3p suppresses proliferation and pro-angiogenic role of keloid fibroblasts by suppressing neuropilin 2

BACKGROUND

Exosomes (Exos) and their contained microRNAs (miRNAs) have been emergingly recognized as key regulators in spanning biological processes, including proliferation and angiogenesis.

AIM OF THE STUDY

This work investigates the function of Exos derived from adipose-derived mesenchymal stem cells (adMSCs) in viability of keloid fibroblasts (KFs).

METHODS

Abnormally expressed miRNAs in keloid tissues were screened using the GEO dataset GSE113620. Meanwhile, miRNAs enriched in adMSC-Exos were predicted by bioinformatics system. Exos were extracted from acquired adMSCs and identified, which were co-incubated with KFs. Uptake of Exos by KFs was examined by fluorescence staining. Viability, proliferation, and apoptosis of KFs were analyzed by CCK-8, EdU labeling, and TUNEL assays. Conditioned medium of KFs was collected to stimulate angiogenesis of human umbilical vein endothelial cells (HUVECs). Binding between miR-7846-3p and neuropilin 2 (NRP2) was validated by luciferase assay. Protein levels of NRP2 and the Hedgehog pathway molecules were analyzed by western blot analysis.

RESULTS

miR-7846-3p was predicted as an exosomal miRNA aberrantly expressed in keloids. AdMSC-Exos reduced viability, proliferation, and apoptosis resistance of KFs, and they blocked the angiogenesis of HUVECs. miR-7846-3p targeted NRP2 mRNA. miR-7846-3p upregulation in KFs suppressed NRP2 expression and reduced the expression of Hedgehog pathway molecules SHH, SMO, and GLI1. Either miR-7846-3p inhibition in Exos or NRP2 overexpression in KFs blocked the effects of Exos and restored the viability, proliferation, and pro-angiogenic role of KFs.

CONCLUSION

This work unravels that adMSC-Exos-derived miR-7846-3p suppresses NRP2 and inactivates the Hedgehog signaling to reduce proliferation and pro-angiogenic role of KFs.

The adipose-derived stem cell peptide ADSCP2 alleviates hypertrophic scar fibrosis via binding with pyruvate carboxylase and remodeling the metabolic landscape

AIM

The purpose of this study was to investigate the function and mechanism of a novel peptide derived from adipose-derived stem cell-conditioned medium (ADSC-CM).

METHODS

Mass spectrometry was applied to identify expressed peptides in ADSC-CM obtained at different time points. The cell counting kit-8 assay and quantitative reverse transcription polymerase chain reactions were performed to screen the functional peptides contained within ADSC-CM. RNA-seq, western blot, a back skin excisional model of BALB/c mice, the peptide pull-down assay, rescue experiments, untargeted metabolomics, and mixOmics analysis were performed to thoroughly understand the functional mechanism of selected peptide.

RESULTS

A total of 93, 827, 1108, and 631 peptides were identified in ADSC-CM at 0, 24, 48, and 72 h of conditioning, respectively. A peptide named ADSCP2 (DENREKVNDQAKL) derived from ADSC-CM inhibited collagen and ACTA2 mRNAs in hypertrophic scar fibroblasts. Moreover, ADSCP2 facilitated wound healing and attenuated collagen deposition in a mouse model. ADSCP2 bound with the pyruvate carboxylase (PC) protein and inhibited PC protein expression. Overexpressing PC rescued the reduction in collagen and ACTA2 mRNAs caused by ADSCP2. Untargeted metabolomics identified 258 and 447 differential metabolites in the negative and positive mode, respectively, in the ADSCP2-treated group. The mixOmics analysis, which integrated RNA-seq and untargeted metabolomics data, provided a more holistic view of the functions of ADSCP2.

CONCLUSION

Overall, a novel peptide derived from ADSC-CM, named ADSCP2, attenuated hypertrophic scar fibrosis in vitro and in vivo, and the novel peptide ADSCP2 might be a promising drug candidate for clinical scar therapy.

Effect of Inflammatory Microenvironment on the Regenerative Capacity of Adipose-Derived Mesenchymal Stem Cells

Adipose-derived mesenchymal stem cells are increasingly being used in regenerative medicine as cell therapy targets, including in the treatment of burns and ulcers. The regenerative potential of AD-MSCs and some of their immunological properties are known from in vitro studies; however, in clinical applications, cells are used in non-ideal conditions and can behave differently in inflammatory environments, affecting the efficacy and outcome of therapy. Our aim was to investigate and map the pathways that the inflammatory microenvironment can induce in these cells. High-throughput gene expression assays were performed on AD-MSCs activated with LPS and TNFα. Analysis of RNA-Seq data showed that control, LPS-treated and TNFα-treated samples exhibited distinct gene expression patterns. LPS treatment increased the expression of 926 genes and decreased the expression of 770 genes involved in cell division, DNA repair, the cell cycle, and several metabolic processes. TNFα treatment increased the expression of 174 genes and decreased the expression of 383 genes, which are related to cell division, the immune response, cell proliferation, and differentiation. We also map the biological pathways by further investigating the most altered genes using the Gene Ontology and KEGG databases. Secreted cytokines, which are important in the immunological response, were also examined at the protein level, and a functional assay was performed to assess wound healing. Activated AD-MSC increased the secretion of IL-6, IL-8 and CXCL-10, and also the closure of wounds. AD-MSCs presented accelerated wound healing under inflammation conditions, suggesting that we could use this cell in clinical application.

Development of Hetero-Cell Type Spheroids Via Core-Shell Strategy for Enhanced Wound Healing Effect of Human Adipose-Derived Stem Cells

BACKGROUND

Stem cell-based therapies have been developed to treat various types of wounds. Human adipose-derived stem cells (hADSCs) are used to treat skin wounds owing to their outstanding angiogenic potential. Although recent studies have suggested that stem cell spheroids may help wound healing, their cell viability and retention rate in the wound area require improvement to enhance their therapeutic efficacy.

METHODS

We developed a core-shell structured spheroid with hADSCs in the core and human dermal fibroblasts (hDFs) in the outer part of the spheroid. The core-shell structure was formed by continuous centrifugation and spheroid incubation. After optimizing the method for inducing uniform-sized core-shell spheroids, cell viability, cell proliferation, migration, and therapeutic efficacy were evaluated and compared to those of conventional spheroids.

RESULTS

Cell proliferation, migration, and involucrin expression were evaluated in keratinocytes. Tubular assays in human umbilical vein endothelial cells were used to confirm the improved skin regeneration and angiogenic efficacy of core-shell spheroids. Core-shell spheroids exhibited exceptional cell viability under hypoxic cell culture conditions that mimicked the microenvironment of the wound area.

CONCLUSION

The improvement in retention rate, survival rate, and angiogenic growth factors secretion from core-shell spheroids may contribute to the increased therapeutic efficacy of stem cell treatment for skin wounds.

Hypoxia-treated umbilical mesenchymal stem cell alleviates spinal cord ischemia-reperfusion injury in SCI by circular RNA circOXNAD1/ miR-29a-3p/ FOXO3a axis

Spinal cord ischemia reperfusion (SCIR) injury leads to spinal cord function injury, neural dysfunction and sometimes paralysis or even paraplegia, which severely impair the physical and mental health of individuals. Mesenchymal stem cells (MSCs) are a group of stem cells that have been widely studied for treatment of various diseases. This work aimed to study the therapeutic potential of hypoxia-induced exosomal circular RNA OXNAD1 from human umbilical cord mesenchymal stem cells (HucMSCs) against SCIR. We established an in vivo rat spinal cord injury (SCI) model and conducted treatment with exosomes that isolated from hypoxia-HucMSCs. Hypoxia-HucMSCs-derived exosomal circOXNAD1 alleviated the spinal cord tissue injury in SCI, improved limb motor function, decreased production of inflammatory factors including the IL-1 β, IL-6, and TNF-α. The in vitro hypoxia and reoxygenation (H/R) model demonstrated that Hypoxia-HucMSCs-derived exosomal circOXNAD1 improved neuron proliferation and alleviated apoptosis. Mechanistically, circOXNAD1 directly interact with miR-29a-3p and miR-29a-3p targets the 3'UTR of FOXO3a in neurons. Inhibition of miR-29a-3p and overexpression of FOXO3a reversed the effects of circOXNAD1 depletion in PC12 cell phenotypes. In conclusion, Hypoxia elevated the level circOXNAD1 in exosomes that derived from HuMSCs. The exosomal circOXNAD1 alleviated SCI through sponging miR-29a-3p and consequently elevated the FOXO3a expression. Our findings provided novel evidence for MSC-derived exosomal circOXNAD1in the treatment of SCI.

Lipoaspirate fluid derived factors and extracellular vesicles accelerate wound healing in a rat burn model

Background: The regenerative capabilities of derivatives derived from the fat layer of lipoaspirate have been demonstrated. However, the large volume of lipoaspirate fluid has not attracted extensive attention in clinical applications. In this study, we aimed to isolate the factors and extracellular vesicles from human lipoaspirate fluid and evaluate their potential therapeutic efficacy. Methods: Lipoaspirate fluid derived factors and extracellular vesicles (LF-FVs) were prepared from human lipoaspirate and characterized by nanoparticle tracking analysis, size-exclusion chromatography and adipokine antibody arrays. The therapeutic potential of LF-FVs was evaluated on fibroblasts in vitro and rat burn model in vivo. Wound healing process was recorded on days 2, 4, 8, 10, 12 and 16 post-treatment. The scar formation was analyzed by histology, immunofluorescent staining and scar-related gene expression at day 35 post-treatment. Results: The results of nanoparticle tracking analysis and size-exclusion chromatography indicated that LF-FVs were enriched with proteins and extracellular vesicles. Specific adipokines (adiponectin and IGF-1) were detected in LF-FVs. In vitro, LF-FVs augmented the proliferation and migration of fibroblasts in a dose-dependent manner. In vivo, the results showed that LF-FVs significantly accelerated burn wound healing. Moreover, LF-FVs improved the quality of wound healing, including regenerating cutaneous appendages (hair follicles and sebaceous glands) and decreasing scar formation in the healed skin. Conclusion: LF-FVs were successfully prepared from lipoaspirate liquid, which were cell-free and enriched with extracellular vesicles. Additionally, they were found to improve wound healing in a rat burn model, suggesting that LF-FVs could be potentially used for wound regeneration in clinical settings.

Adipose-Derived Mesenchymal Stromal Cells: A Tool for Bone and Cartilage Repair

The osteogenic and chondrogenic differentiation ability of adipose-derived mesenchymal stromal cells (ASCs) and their potential therapeutic applications in bone and cartilage defects are reported in this review. This becomes particularly important when these disorders can only be poorly treated by conventional therapeutic approaches, and tissue engineering may represent a valuable alternative. Being of mesodermal origin, ASCs can be easily induced to differentiate into chondrocyte-like and osteocyte-like elements and used to repair damaged tissues. Moreover, they can be easily harvested and used for autologous implantation. A plethora of ASC-based strategies are being developed worldwide: they include the transplantation of freshly harvested cells, in vitro expanded cells or predifferentiated cells. Moreover, improving their positive effects, ASCs can be implanted in combination with several types of scaffolds that ensure the correct cell positioning; support cell viability, proliferation and migration; and may contribute to their osteogenic or chondrogenic differentiation. Examples of these strategies are described here, showing the enormous therapeutic potential of ASCs in this field. For safety and regulatory issues, most investigations are still at the experimental stage and carried out in vitro and in animal models. Clinical applications have, however, been reported with promising results and no serious adverse effects.

Use of Poly Lactic-co-glycolic Acid Nano and Micro Particles in the Delivery of Drugs Modulating Different Phases of Inflammation

Chronic inflammation contributes to the pathogenesis of many diseases, including apparently unrelated conditions such as metabolic disorders, cardiovascular diseases, neurodegenerative diseases, osteoporosis, and tumors, but the use of conventional anti-inflammatory drugs to treat these diseases is generally not very effective given their adverse effects. In addition, some alternative anti-inflammatory medications, such as many natural compounds, have scarce solubility and stability, which are associated with low bioavailability. Therefore, encapsulation within nanoparticles (NPs) may represent an effective strategy to enhance the pharmacological properties of these bioactive molecules, and poly lactic-co-glycolic acid (PLGA) NPs have been widely used because of their high biocompatibility and biodegradability and possibility to finely tune erosion time, hydrophilic/hydrophobic nature, and mechanical properties by acting on the polymer's composition and preparation technique. Many studies have been focused on the use of PLGA-NPs to deliver immunosuppressive treatments for autoimmune and allergic diseases or to elicit protective immune responses, such as in vaccination and cancer immunotherapy. By contrast, this review is focused on the use of PLGA NPs in preclinical in vivo models of other diseases in which a key role is played by chronic inflammation or unbalance between the protective and reparative phases of inflammation, with a particular focus on intestinal bowel disease; cardiovascular, neurodegenerative, osteoarticular, and ocular diseases; and wound healing.

Therapeutic Benefits of Stem Cells and Exosomes for Sulfur-Mustard-Induced Tissue Damage

Sulfur mustard (SM) is a highly toxic chemical agent that causes severe tissue damage, particularly to the eyes, lungs, and skin. Despite advances in treatment, there is a need for more effective therapies for SM-induced tissue injury. Stem cell and exosome therapies are emerging as promising approaches for tissue repair and regeneration. Stem cells can differentiate into multiple cell types and promote tissue regeneration, while exosomes are small vesicles that can deliver therapeutic cargo to target cells. Several preclinical studies demonstrated the potential of stem cell, exosome, or combination therapy for various tissue injury, showing improvements in tissue repairing, inflammation, and fibrosis. However, there are also challenges associated with these therapies, such as the requirement for standardized methods for exosome isolation and characterization, the long-term safety and efficacy and reduced SM-induced tissue injury of these therapies. Stem cell or exosome therapy was used for SM-induced eye and lung injury. Despite the limited data on the use for SM-induced skin injury, this therapy is a promising area of research and may offer new treatment options in the future. In this review, we focused on optimizing these therapies, evaluating their safety and efficacy, and comparing their efficacy to other emerging therapeutic approaches potentially for SM-induced tissue injury in the eye, lung, and skin.

Calcium silicate-stimulated adipose-derived stem cells promote angiogenesis and improve skin wound healing

Skin wound healing is a complicated process involving proliferation, inflammation, coagulation, and hemostasis, and scar tissue formation of wound repairing. Adipose-derived stem cells (ADSCs) have presented potential therapeutic effects in the non-healing and chronic wound. Calcium silicate (CS) ceramics have been identified as a new type of bioceramics for tissue construction and regeneration. Here, we aimed to explore the impact of CS on the regulation of ADSCs-mediated wound healing. Significantly, CS was able to dose-dependently enhance the proliferation of ADSCs. CS inhibited terminal deoxynucleotidyl transferase dUTP nick end labeling positive cells in the H₂O₂-treated ADSCs. Similarly, the Bcl-2 expression was elevated while Bax and cleaved caspase-3 expression were repressed by CS in the cells. CS could induce migration and reduce oxidative stress of ADSCs. Moreover, immunofluorescence analysis and Western blot analysis showed that CS could promote CXCR4 expression in ADSCs. Moreover, CS-stimulated ADSCs enhanced migration and angiogenic capacity of HUVEC. Importantly, CS-stimulated ADSCs improved wound healing in full-thickness skin defect mouse model. Thus, we conclude that CS improves ADSCs-attenuated wound healing in vivo and in vitro. Our finding presents novel insight in the scenario that CS regulates ADSCs and wound healing. CS may be applied as potential materials for the treatment of wound healing.

The Potential of MSC-Based Cell-Free Therapy in Wound Healing-A Thorough Literature Review

A wound is an interruption of the normal anatomic structure and function of the skin, which is critical in protecting against foreign pathogens, regulating body temperature and water balance. Wound healing is a complex process involving various phases, including coagulation, inflammation, angiogenesis, re-epithelialization, and re-modeling. Factors such as infection, ischemia, and chronic diseases such as diabetes can compromise wound healing, leading to chronic and refractory ulcers. Mesenchymal stem cells (MSCs) have been used to treat various wound models due to their paracrine activity (secretome) and extracellular vehicles (exosomes) that contain several molecules, including long non-coding RNAs (lncRNAs), micro-RNAs (miRNAs), proteins, and lipids. Studies have shown that MSCs-based cell-free therapy using secretome and exosomes has great potential in regenerative medicine compared to MSCs, as there are fewer safety concerns. This review provides an overview of the pathophysiology of cutaneous wounds and the potential of MSCs-based cell-free therapy in each phase of wound healing. It also discusses clinical studies of MSCs-based cell-free therapies.

Magnetic Nanostructures and Stem Cells for Regenerative Medicine, Application in Liver Diseases

The term "liver disease" refers to any hepatic condition that leads to tissue damage or altered hepatic function and can be induced by virus infections, autoimmunity, inherited genetic mutations, high consumption of alcohol or drugs, fat accumulation, and cancer. Some types of liver diseases are becoming more frequent worldwide. This can be related to increasing rates of obesity in developed countries, diet changes, higher alcohol intake, and even the coronavirus disease 2019 (COVID-19) pandemic was associated with increased liver disease-related deaths. Although the liver can regenerate, in cases of chronic damage or extensive fibrosis, the recovery of tissue mass is impossible, and a liver transplant is indicated. Because of reduced organ availability, it is necessary to search for alternative bioengineered solutions aiming for a cure or increased life expectancy while a transplant is not possible. Therefore, several groups were studying the possibility of stem cells transplantation as a therapeutic alternative since it is a promising strategy in regenerative medicine for treating various diseases. At the same time, nanotechnological advances can contribute to specifically targeting transplanted cells to injured sites using magnetic nanoparticles. In this review, we summarize multiple magnetic nanostructure-based strategies that are promising for treating liver diseases.

Modification of the small intestinal submucosa membrane with oligopeptides screened from intrinsically disordered regions to promote angiogenesis and accelerate wound healing

A slow vascularization rate is considered one of the major disadvantages of biomaterials used for accelerating wound healing. Several efforts, including cellular and acellular technologies, have been made to facilitate biomaterial-induced angiogenesis. However, no well-established techniques for promoting angiogenesis have been reported. In this study, a small intestinal submucosa (SIS) membrane modified by an angiogenesis-promoting oligopeptide (QSHGPS) screened from intrinsically disordered regions (IDRs) of MHC class II was used to promote angiogenesis and accelerate wound healing. Because the main component of SIS membranes is collagen, the collagen-binding peptide sequence TKKTLRT and the pro-angiogenic oligopeptide sequence QSHGPS were used to construct chimeric peptides to obtain specific oligopeptide-loaded SIS membranes. The resulting chimeric peptide-modified SIS membranes (SIS-L-CP) significantly promoted the expression of angiogenesis-related factors in umbilical vein endothelial cells. Furthermore, SIS-L-CP exhibited excellent angiogenic and wound-healing abilities in a mouse hindlimb ischaemia model and a rat dorsal skin defect model. The high biocompatibility and angiogenic capacity of the SIS-L-CP membrane make it promising in angiogenesis- and wound healing-related regenerative medicine.

Stem cell-derived exosomes: emerging therapeutic opportunities for wound healing

Wound healing is a dynamic and highly sequential process involving a series of overlapping spatial and temporal phases, including hemostasis, inflammation, proliferation, and tissue remodeling. Mesenchymal stem cells (MSCs) are multipotent stem cells with self-renewal, multidirectional differentiation potential, and paracrine regulation. Exosomes are subcellular vesicular components 30-150 nm in size and are novel carriers of intercellular communication in regulating the biological behaviors of skin cells. Compared to MSCs, MSC-derived exosomes (MSC-exos) possess lower immunogenicity, easy storage, and highly effective biological activity. MSC-exos, mainly derived from adipose-derived stem cells (ADSCs), bone marrow-derived MSCs (BMSCs), human umbilical cord MSCs (hUC-MSCs), and other stem cell types, play a role in shaping the activity of fibroblasts, keratinocytes, immune cells, and endothelial cells in diabetic wounds, inflammatory wound repair, and even wound-related keloid formation. Therefore, this study focuses on the specific roles and mechanisms of different MSC-exos in wound healing, as well as the current limitations and various perspectives. Deciphering the biological properties of MSC-exos is crucial to providing a promising cell-free therapeutic tool for wound healing and cutaneous regeneration.

Mesenchymal stem cells transplantation for perianal fistulas: a systematic review and meta-analysis of clinical trials

BACKGROUND

Perianal fistulas, characterised as granulomatous inflammation of fistulas around the anal canal, are associated with significant morbidity resulting in a negative impact on quality of life and a tremendous burden to the healthcare system. Treatment of anal fistulas usually consists of anal surgery; however, results of closure rates are not satisfactory especially with complex perianal fistulas, after which many patients may suffer from anal incontinence. Recently, the administration of mesenchymal stem cells (MSCs) has shown promising efficacy. Herein, we aim to explore whether MSCs are effective for complex perianal fistulas and if they have either short-term, medium-term, long-term or over-long-term efficacy. Additionally, we want to elucidate whether factors such as drug dosage, MSC source, cell type, and disease aetiology influence treatment efficacy. We searched four online databases and analysed data based on information within the clinical trials registry. The outcomes of eligible trials were analysed with Review Manager 5.4.1. Relative risk and related 95% confidence interval were calculated to compare the effect between the MSCs and control groups. In addition, the Cochrane risk of bias tool was applied to evaluate the bias risk of eligible studies. Meta-analyses showed that therapy with MSCs was superior to conventional treatment for complex perianal fistulas in short-, long- and over-long-term follow-up phases. However, there was no statistical difference in treatment efficacy in the medium term between the two methods. Subgroup meta-analyses showed factors including cell type, cell source and cell dosage were superior compared to the control, but there was no significant difference between different experimental groups of those factors. Besides, local MSCs therapy has shown more promising results for fistulas as a result of Crohn's Disease (CD). Although we tend to maintain that MSCs therapy is effective for cryptoglandular fistulas equally, more studies are needed to confirm this conclusion in the future.

SHORT CONCLUSION

MSCs Transplantation could be a new therapeutic method for complex perianal fistulas of both cryptoglandular and CD origin showing high efficacy in the short-term to over-long-term phases, as well as high efficacy in sustained healing. The difference in cell types, cell sources and cell dosages did not influence MSCs' efficacy.

Osteogenic Differentiation Effect of Human Periodontal Ligament Stem-Cell Initial Cell Density on Autologous Cells and Human Bone Marrow Stromal Cells

Stem cells have differentiation and regulation functions. Here, we discussed the impact of cell culture density on stem cell proliferation, osteoblastogenesis, and regulation. To discuss the effect of the initial culture density of human periodontal ligament stem cells (hPDLSCs) on the osteogenic differentiation of autologous cells, we found that the hPDLSC proliferation rate decreased with an increase in the initial plating density (0.5-8 × 10⁴ cells/cm²) for the 48 h culture cycle. After hPDLSCs induced osteogenic differentiation for 14 days with different initial cell culture densities, the expression of osteoprotegerin (OPG) and runt-related transcription factor 2(RUNX2) and the OPG/ Receptor Activator of Nuclear Factor-κ B Ligand (RANKL) ratio were the highest in the hPDLSCs initially plated at a density of 2 × 10⁴ cells/cm², and the average cell calcium concentration was also the highest. To study hPDLSCs regulating the osteoblastic differentiation of other cells, we used 50 μg/mL of secreted exosomes derived from hPDLSCs cultured using different initial cell densities to induce human bone marrow stromal cell (hBMSC) osteogenesis. After 14 days, the results indicated that the gene expression of OPG, Osteocalcin(OCN,)RUNX2, and osterix and the OPG/RANKL ratio were the highest in the 2 × 10⁴ cells/cm² initial cell density group, and the average calcium concentration was also the highest. This provides a new idea for the clinical application of stem cell osteogenesis.

Efficacy of mesenchymal stem cell therapy in rodent models of radiation-induced xerostomia and oral mucositis: a systematic review

BACKGROUND

Radiation-induced xerostomia and oral mucositis are serious complications of radiation therapy for head and neck cancers. Current treatment options have limited efficacy. Mesenchymal stem cell (MSC) therapy has shown promising results in supporting the restoration of glandular secretion function and the regeneration of damaged tissues. This study aim to (1) assess the quality of evidence for MSCs treatment in rodent models of radiation-induced oral complications and (2) determine whether MSCs can improve the therapeutic effect of radiation-induced oral mucositis.

METHODS

Intervention studies using MSCs in rodent models were comprehensively retrieved in the Pubmed, Medline, Embase, Web of Science, and Cochrane library databases on June 1, 2022. The quality of all in vivo experiments was assessed using SYRCLE, and this article is written following the PRISMA guidelines.

RESULTS

A total of 12 studies were included in this systematic review. The study found that in animal models of radiation-induced xerostomia, MSCs could increase salivary protein secretion, improve SFR, shorten the salivary lag time, anti-apoptosis, etc. In animal models of radiation-induced oral mucositis, MSCs improve the micromorphology and macromorphology of RIOM. Moreover, the effect of MSCs on the modification of ulcer duration and latency may be related to the time of MSCs transplantation but further studies are needed.

CONCLUSION

The results of our systematic review suggest that MSCs appeared to be effective in the treatment of radiation-induced xerostomia and oral mucositis.

Curcumin preconditioned mesenchymal stem cells derived exosomes transplantation ameliorate and protect against non- alcoholic steatohepatitis by regulation the expression of key genes of inflammation and oxidative stress

BACKGROUND

Mesenchymal stem cells (MSCs) derived exosomes (MSCs/Exo) is considered a new strategy in cell free regenerative therapy. Curcumin preconditioning of MSCs reported to improve the anti- inflammatory and immunomodulatory properties of MSCs. We investigated the efficacy of exosome (Exo) obtained from curcumin-preconditioned MSCs (MSCs/Exo-Cur) vs. MSC/Exo without curcumin to ameliorate and prevent recurrence of non-alcoholic fatty liver (NASH) disease.

METHODS AND RESULTS

In-vivo, methionine/choline-deficient diet (MCD) induced mice non-alcoholic fatty liver disease (NASH) were injected with MSCs/Exo without curcumin or MSCs/Exo-Cur with curcumin. We found that mice treated with MSCs/Exo-Cur had significantly ameliorated steatosis, inflammation, as evaluated by the reduced fibrosis in histopathological examination, decreased the serum level of liver enzymes (p < 0.001), liver triglycerides (TG) (p < 0.001) and cholesterol (Ch) (p < 0.001) and increased the lipid peroxidation (p < 0.001) compared to MSCs/Exo-treated mice. These effects remained for 3 months after treatment in MSCs/Exo-Cur-treated mice while features of NASH returned in MSCs/Exo-treated group. In vitro, HepG2 cells were cultured with palmitic acid (PA) and treated with MSCs/Exo or MSCs/Exo-Cur: the MSCs/Exo-Cur exposure reversed the lipotoxic effect from 4.5 to 1.7 fold vs 4.0 fold in MSCs/Exo and oxidative stress in PA-treated HepG2 cells (p < 0.001). We found that MSCs/Exo-Cur regulated the key markers of inflammatory and oxidative stress, genes responsible for fibrogenesis of the liver, key genes of lipid synthesis and transport . Interestingly, MSCs/Exo-Cur significantly down regulated the ASK-JNK-BAX genes involved in mitochondrial stress and apoptosis compared to MSCs/Exo (p < 0.001).

CONCLUSION

Our study indicated that exosomes derived from curcumin preconditioned MSCs were able to ameliorate and protect against recurrence of NASH and regulated inflammatory, oxidative stress and mitochondrial-dependent apoptosis ASK-JNK-BAX genes.

Cell-based wound dressing: Bilayered PCL/gelatin nanofibers-alginate/collagen hydrogel scaffold loaded with mesenchymal stem cells

Wound dressing is applied to promote the healing process, wound protection, and additionally regeneration of injured skin. In this study, a bilayer scaffold composed of a hydrogel and nanofibers was fabricated to improve the regeneration of injured skin. To this end, polycaprolactone/gelatin (PCL/Gel) nanofibers were electrospun directly on the prepared collagen/alginate (Col/Alg) hydrogel. The bilayer scaffold was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), mechanical properties, and swelling/degradation time. Cytotoxicity assays were evaluated using MTT assay. Then, the nanofiber and bilayer scaffolds were seeded with Adipose-derived stem cells (ADSCs). ADSCs were isolated from rat adipose tissue and analyzed using flow cytometry, in advance. Full-thickness wounds on the backs of rats were dressed with ADSCs-seeded bilayer scaffolds and nanofibers. Histopathological evaluations were performed after 14 and 21 days using H&E (hematoxylin and eosin) staining. The results indicated that re-epithelialization, angiogenesis, and collagen remodeling were enhanced in ADSCs-seeded bilayer scaffolds and nanofibers in comparison with the control group. In conclusion, the best re-epithelialization, collagen organization, neovascularization, and low presence of inflammation in the wound area were observed in the ADSCs-seeded bilayer scaffolds.

Function and mechanism of mesenchymal stem cells in the healing of diabetic foot wounds

Diabetes has become a global public health problem. Diabetic foot is one of the most severe complications of diabetes, which often places a heavy economic burden on patients and seriously affects their quality of life. The current conventional treatment for the diabetic foot can only relieve the symptoms or delay the progression of the disease but cannot repair damaged blood vessels and nerves. An increasing number of studies have shown that mesenchymal stem cells (MSCs) can promote angiogenesis and re-epithelialization, participate in immune regulation, reduce inflammation, and finally repair diabetic foot ulcer (DFU), rendering it an effective means of treating diabetic foot disease. Currently, stem cells used in the treatment of diabetic foot are divided into two categories: autologous and allogeneic. They are mainly derived from the bone marrow, umbilical cord, adipose tissue, and placenta. MSCs from different sources have similar characteristics and subtle differences. Mastering their features to better select and use MSCs is the premise of improving the therapeutic effect of DFU. This article reviews the types and characteristics of MSCs and their molecular mechanisms and functions in treating DFU to provide innovative ideas for using MSCs to treat diabetic foot and promote wound healing.

Recent Advances in Nano-Drug Delivery Systems for the Treatment of Diabetic Wound Healing

Diabetes mellitus (DM) induced wound healing impairment remains a serious health problem and burden on the clinical obligation for high amputation rates. Based on the features of wound microenvironment, biomaterials loading specific drugs can benefit diabetic wound treatment. Drug delivery systems (DDSs) can carry diverse functional substances to the wound site. Nano-drug delivery systems (NDDSs), benefiting from their features related to nano size, overcome limitations of conventional DDSs application and are considered as a developing process in the wound treatment field. Recently, a number of finely designed nanocarriers efficiently loading various substances (bioactive and non-bioactive factors) have emerged to circumvent constraints faced by traditional DDSs. This review describes various recent advances of nano-drug delivery systems involved in mitigating diabetes mellitus-based non-healing wounds.

Adipose-derived mesenchymal stem cells promote salivary duct regeneration via a paracrine effect

OBJECTIVES

The self-regeneration of exocrine tissues, including salivary glands, is limited and their regeneration mechanism has not yet been fully elucidated. Here we identify the role of adipose-derived mesenchymal stem cells (AMSCs) in salivary gland regeneration.

METHODS

AMSCs expressing mesenchymal stem cell markers were applied to a submandibular gland injury model and the mechanism of salivary gland repair and regeneration was analyzed.

RESULTS

Transplanted green fluorescent protein (GFP)-labeled AMSCs grew tightly together and promoted ductal regeneration in the regenerative nodule, with slight infiltration of nonspecific immune cells. A comprehensive gene analysis through RNA-sequencing revealed increased expression of bone morphogenetic protein (BMP), transforming growth factor (TGF), and Wnt in AMSC-transplanted regenerative nodules. The factors released from AMSCs scavenge hydrogen peroxidase-induced reactive oxygen species (ROS) through Wnt promoter activity in vitro. Furthermore, AMSC-conditioned medium recovered the growth of the hydrogen peroxidase-damaged primordium of the submandibular gland culture ex vivo.

CONCLUSIONS

These results suggest that AMSC-released factors scavenge ROS and maintain salivary gland repair and regeneration via paracrine effects. Thus, AMSCs could be a practical and applicable tool for use in salivary gland regeneration.