Human Bone Marrow Mesenchymal Stem Cell Conditioned Medium Promotes Wound Healing in Deep Second-Degree Burns in Male Rats

Mesenchymal stem cells biological and biotechnological advances: Implications for clinical applications

BACKGROUND

Mesenchymal stem cells (MSCs) are multipotent stem cells that are able to differentiate into multiple lineages including bone, cartilage, muscle and fat. They hold immunomodulatory properties and therapeutic ability to treat multiple diseases, including autoimmune and chronic degenerative diseases. In this article, we reviewed the different biological properties, applications and clinical trials of MSCs. Also, we discussed the basics of manufacturing conditions, quality control, and challenges facing MSCs in the clinical setting.

METHODS

Extensive review of the literature was conducted through the databases PubMed, Google Scholar, and Cochrane. Papers published since 2015 and covering the clinical applications and research of MSC therapy were considered. Furthermore, older papers were considered when referring to pioneering studies in the field.

RESULTS

The most widely studied stem cells in cell therapy and tissue repair are bone marrow-derived mesenchymal stem cells. Adipose tissue-derived stem cells became more common and to a lesser extent other stem cell sources e.g., foreskin derived MSCs. MSCs therapy were also studied in the setting of COVID-19 infections, ischemic strokes, autoimmune diseases, tumor development and graft rejection. Multiple obstacles, still face the standardization and optimization of MSC therapy such as the survival and the immunophenotype and the efficiency of transplanted cells. MSCs used in clinical settings displayed heterogeneity in their function despite their extraction from healthy donors and expression of similar surface markers.

CONCLUSION

Mesenchymal stem cells offer a rising therapeutic promise in various diseases. However, their potential use in clinical applications requires further investigation.

Bacterial cellulose as an ideal potential treatment for burn wounds: A comprehensive review

Burn wound regeneration is a complex process, which has many serious challenges such as slow wound healing, secondary infection, and inflammation. Therefore, it is essential to utilise appropriate biomaterials to accelerate and guide the wound healing process. Bacterial cellulose (BC), a natural polymer synthesised by some bacteria, has attracted much attention for wound healing applications due to its unique properties including excellent physicochemical and mechanical properties, simple purification process, three-dimensional (3D) network structure similar to extracellular matrix, high purity, high water holding capacity and significant permeability to gas and liquid. BC's lack of antibacterial activity significantly limits its biomedical and tissue engineering application, but adding antimicrobial agents to it remarkably improves its performance in tissue regeneration applications. Burn wound healing is a complex long-lasting process. Using biomaterials in wound treatment has shown that they can satisfactorily accelerate wound healing. The purpose of this review is to elaborate on the importance of BC-based structures as one of the most widely used modern wound dressings in the treatment of burn wounds. In addition, the combination of various drugs, agents, cells and biomolecules with BC to expand its application in burn injury regeneration is discussed. Finally, the main challenges and future development direction of BC-based structures for burn wound repair are considered. The four most popular search engines PubMed/MEDLINE, Science Direct, Scopus and Google Scholar were used to help us find relevant papers. The most frequently used keywords were bacterial cellulose, BC-based biocomposite, wound healing, burn wound and vascular graft.

Single dose human perinatal stem cells accelerate healing of cold-induced rat burn wound

Temporal phases of wound healing and their corresponding healing factors are essential in wound regeneration. Mesenchymal stem cells (MSCs) accelerate wound healing via their paracrine secretions by enhancing cell migration, angiogenesis, and reducing inflammation. This study evaluated the local therapeutic effect of human umbilical cord MSCs (hUCMSCs) in the healing of cold-induced burn wounds. An in vitro wound (scratch) was developed in rat skin fibroblasts. The culture was maintained in the conditioned medium (CM) which was prepared by inducing an artificial wound in hUCMSCs in a separate experiment. Treated fibroblasts were analyzed for the gene expression profile of healing mediators involved in wound closure. Findings revealed enhanced cell migration and increased levels of healing mediators in the treated fibroblasts relative to the untreated group. Cold-induced burn wounds were developed in Wistar rats, followed by a single injection of hUCMSCs. Wound healing pattern was examined based on the healing phases: hemostasis/inflammation (Days 1, 3), cell proliferation (Day 7), and remodeling (Day 14). Findings exhibited enhanced wound closure in the treated wound. Gene expression, histological, and immunohistochemical analyses further confirmed enhanced wound regeneration after hUCMSC transplantation. Temporal gene expression profile revealed that the level of corresponding cytokines was substantially increased in the treated wound as compared with the control, indicating improvement in the processes of angiogenesis and remodeling, and a substantial reduction in inflammation. Histology revealed significant collagen formation along with regenerated skin layers and appendages, whereas immunohistochemistry exhibited increased neovascularization during remodeling. Leukocyte infiltration was also suppressed in the treated group. Overall findings demonstrate that a single dose of hUCMSCs enhances wound healing in vivo, and their secreted growth factors accelerate cell migration in vitro.

Mesenchymal stem cell transplantation in burn wound healing: uncovering the mechanisms of local regeneration and tissue repair

Burn injuries pose a significant healthcare burden worldwide, often leading to long-term disabilities and reduced quality of life. To explore the impacts of the transplantation of mesenchymal stem cells (MSCs) on the healing of burns and the levels of serum cytokines, 60 fully grown Sprague-Dawley rats were randomly divided into three groups (n = 20 each): group I (control), group II (burn induction), and group III (burn induction + bone marrow (BM)-MSC transplantation). Groups II and III were further divided into four subgroups (n = 5 each) based on euthanasia duration (7, 14, 21, and 28 days post transplant). The experiment concluded with an anesthesia overdose for rat death. After 7, 14, 21, and 28 days, the rats were assessed by clinical, laboratory, and histopathology investigations. The results revealed significant improvements in burn healing potentiality in the group treated with MSC. Furthermore, cytokine levels were measured, with significant increases in interleukin (IL)-6 and interferon alpha (IFN) observed, while IL-10 and transforming growth factor beta (TGF-β) decreased at 7 days and increased until 28 days post burn. Also, the group that underwent the experiment exhibited increased levels of pro-inflammatory cytokines and the anti-inflammatory cytokine IL-10 when compared to the control group. Histological assessments showed better re-epithelialization, neovascularization, and collagen deposition in the experimental group, suggesting that MSC transplantation in burn wounds may promote burn healing by modulating the immune response and promoting tissue regeneration.

Indirect co-culture of islet cells in 3D biocompatible collagen/laminin scaffold with angiomiRs transfected mesenchymal stem cells

Diabetes is an autoimmune disease in which the pancreatic islets produce insufficient insulin. One of the treatment strategies is islet isolation, which may damage these cells as they lack vasculature. Biocompatible scaffolds are one of the efficient techniques for dealing with this issue. The current study is aimed to determine the effect of transfected BM-MSCS with angiomiR-126 and -210 on the survival and functionality of islets loaded into a 3D scaffold via laminin (LMN). AngiomiRs/Poly Ethylenimine polyplexes were transfected into bone marrow-mesenchymal stem cells (BM-MSCs), followed by 3-day indirect co-culturing with islets laden in collagen (Col)-based hydrogel scaffolds containing LMN. Islet proliferation and viability were significantly increased in LMN-containing scaffolds, particularly in the miRNA-126 treated group. Insulin gene expression was superior in Col scaffolds, especially, in the BM-MSCs/miRNA-126 treated group. VEGF was upregulated in the LMN-containing scaffolds in both miRNA-treated groups, specifically in the miRNA-210, leading to VEGF secretion. MiRNAs' target genes showed no downregulation in LMN-free scaffolds; while a drastic downregulation was seen in the LMN-containing scaffolds. The highest insulin secretion was recorded in the Oxidized dextran (Odex)/Col^LMN+ group with miRNA-126. LMN-containing biocompatible scaffolds, once combined with angiomiRs and their downstream effectors, promote islets survival and restore function, leading to enhanced angiogenesis and glycemic status.

Effect of stem cell treatment on burn wounds: A systemic review and a meta-analysis

A meta-analysis was performed to evaluate the effect of stem cells treatment in managing burn wounds. A systematic literature search up to March 2022 incorporated 24 studies reported between 2013 and 2021 including 400 animals with burn wounds at the beginning of the study; 211 were using stem cells treatment, and 189 controlled. Statistical tools like the contentious method were used within a random or fixed-influence model to establish the mean difference (MD) with 95% confidence intervals (CIs) to evaluate the influence of stem cells treatment in managing burn wounds. Stem cells treatment had a significantly higher burn wound healing rate (MD, 15.18; 95% CI, 11.29-19.07, P < .001), higher blood vessel number (MD, 12.28; 95% CI, 10.06-14.51, P < .001), higher vascular endothelial growth factor (MD, 10.24; 95% CI, 7.19-13.29, P < .001), lower interleukin-1 level (MD, -98.48; 95% CI, -155.33 to -41.63, P < .001), and lower tumour necrosis factor α level (MD, -28.71; 95% CI, -46.65 to -10.76, P < .002) compared with control in animals' models with burn wounds. Stem cells treatment had a significantly higher burn wound healing rate, higher blood vessel number, higher vascular endothelial growth factor, lower interleukin-1 level, and lower tumour necrosis factor α level compared with control in animals' models with burn wounds. Further studies are required to validate these findings.

Engineered stem cell exosomes for oral and maxillofacial wound healing

Wound healing of the oral and maxillofacial area affects the quality of life and mental health of the patient; therefore, effective therapies are required to promote wound healing. However, traditional treatment methods have limited efficacy. Exosomes secreted by stem cells used for oral and maxillofacial wound healing have shown outstanding results. Stem cell-derived exosomes possess the regenerative and repair ability of stem cells. Moreover, they are nontumorigenic and have good biosafety. However, the application of natural stem cell exosomes is limited owing to their low yield, impurity, lack of targeting, and low drug delivery rate. Many modification methods have been developed to engineered stem cell exosomes with beneficial properties, such as modifying parent cells and directly processing stem cell exosomes. These methods include coincubation, genetic engineering, electroporation, ultrasound, and artificial synthesis of engineered stem cell exosomes. These engineered stem cell exosomes can cargo nucleic acids, proteins, and small molecules. This gives them anti-inflammatory and cell proliferation regulatory abilities and enables the targeted promotion of efficient soft tissue repair after trauma. Engineered stem cell exosomes can decrease inflammation, promote fibroblast proliferation, and angiogenesis, and decrease scar formation to promote oral and maxillofacial wound healing, including diabetic and burn wounds. Thus, engineered stem cell exosomes are an effective treatment that has the potential for oral and maxillofacial wound healing.

Increasing angiogenic efficacy of conditioned medium using light stimulation of human adipose-derived stem cells

Conditioned medium (CM) contains various therapeutic molecules produced by cells. However, the low concentration of therapeutic molecules in CM is a major challenge for successful tissue regeneration. Here, we aim to develop a CM enriched in angiogenic paracrine factors for the treatment of ischemic diseases. Combining spheroidal culture and light irradiation significantly upregulates the angiogenic factor expression in human adipose-derived stem cells (hADSCs). Spheroids of light-irradiated hADSCs (SR group) show significantly enhanced expression of angiogenic paracrine factors compared with spheroids without light stimulation. Enhanced viability, migration, and angiogenesis are observed in cells treated with CM derived from the SR group. Furthermore, we performed in vivo experiments using a mouse hindlimb ischemia model; the results demonstrate that CM derived from densely cultured spheroids of light-irradiated hADSCs induced increased angiogenesis in vivo. In conclusion, our proposed approach of using light to stimulate stem cells may overcome the major drawbacks of CM-based therapies.

Combining spheroidal culture of human adipose-derived stem cells with light irradiation enhances angiogenic growth factor secretion in conditioned media, which can improve angiogenesis in a mouse hindlimb ischemia model.

SDF-1α loaded bioengineered human amniotic membrane-derived scaffold transplantation in combination with hyperbaric oxygen improved diabetic wound healing

Based on its multifactorial nature, successful treatment of diabetic wounds requires combinatorial approach. In this regard, we hypothesized that engraftment of a bioengineered micro-porous three-dimensional human amniotic membrane-scaffold (HAMS) loaded by SDF-1α (SHAMS) in combination with hyperbaric oxygen (HBO), throughout mobilization and recruitment of endothelial progenitor cells (EPCs), could accelerate wound healing in rats with type 1 diabetes mellitus. To test this hypothesis, 30 days after inducting diabetes, an ischemic wound was created in rat skin and treatments were performed for 21 days. In addition to wounded non-diabetic (ND) group, diabetic animals were randomly divided into non-treated (NT-D), HBO-treated (HBO-D), HBO-treated plus HAMS transplantation (HBO+HAMS-D) or HBO-treated in combination with SHAMS transplantation (HBO+SHAMS-D) groups. Our results on post-wounding days 7, 14 and 21 showed that the wound closure, volume of new dermis and epidermis, numerical density of basal cells of epidermis, fibroblasts and blood vessels, number of proliferating cells, deposition of collagen and biomechanical properties of healed wound were considerably higher in both HBO+HAMS-D and HBO+SHAMS-D groups in comparison to those of the NT-D and HBO-D groups, and were the highest in HBO+SHAMS-D ones. The transcripts for Vegf, bFgf, and Tgf-β genes were significantly upregulated in all treatment regimens compared to NT-D group and were the highest for HBO+SHAMS-D group. This is while expression of Tnf-α and Il-1β as well as cell density of neutrophil and macrophage decreased more significantly in HBO+SHAMS-D group as compared with NT-D or HBO-D groups. Overall, it was found that using both HAMS transplantation and HBO treatment has more impact on diabetic wound healing. Moreover, SDF-1α loading on HAMS could transiently improve the wound healing process, as compared with the HBO+HAMS-D group on day 7 only.

Secretomes as an emerging class of bioactive ingredients for enhanced cosmeceutical applications

Skin aging is predominantly caused by either intrinsic or extrinsic factors, leading to undesirable skin features. Advancements in both molecular and cellular fields have created possibilities in developing novel stem cell-derived active ingredients for cosmeceutical applications and the beauty industry. Mesenchymal stromal cell (MSC)-derived secretomes or conditioned media hold great promise for advancing skin repair and regeneration due to the presence of varying cytokines. These cytokines signal our cells and trigger biological mechanisms associated with anti-inflammatory, antioxidant, anti-aging, proliferative, and immunomodulatory effects. In this review, we discuss the potential of MSC secretomes as novel biomaterials for skincare and rejuvenation by illustrating their mechanism of action related to wound healing, anti-aging, and whitening properties. The advantages and disadvantages of secretomes are compared to both plant-based and animal-derived extracts. In addition, this paper reviews the current safety standards, regulations, market products and research work related to the cosmeceutical applications of secretomes along with strategies to maintain and improve the therapeutic efficacy and production of secretomes. The future outlook of beauty industry is also presented. Lastly, we highlight significant challenges to be addressed for the clinical realization of MSC secretomes-based skin therapies as well as providing perspectives for the future direction of secretomes.

Effect of Thymosin β4 on Deep Second-Degree Scald Wound Healing in Rats via Wnt/β-Catenin Pathway

<sec> <title>Objective:</title> The purpose of this research is to explore the influences of thymosin β4 (Tβ4) in deepsecond-degree scald wound healing of rat skin and its relationship with Wnt/β-catenin pathway. </sec> <sec> <title>Methods:</title> Deep second-degree scalded model rats were prepared and divided into normal saline (NS) treatment group, Tβ4 treatment group and FH535 inhibitor group. Then, the concentrations of inflammatory factors in the rats were monitored via adopting the correlated TNF-α and IL-1β ELISA kits. In the meantime, the wound healing rate was analyzed via photography. Subsequently, the qRTPCR procedure was wielded to determine Wnt1 and β-catenin expression in wound tissues, and the degree of wound tissue injury was examined via hematoxylin and eosin (HE) staining. Finally, Western blotting (WB) was adopted to assess Wnt/β-catenin pathway-associated protein levels. </sec> <sec> <title>Results:</title> Releasing amount of TNF-α and IL-1β were conspicuously up-regulated after scalding (p <0.01), and Wnt1 and β-catenin expression at molecular transcription level was also significantly raised (p < 0.01). Besides, treatment with 18 μg of Tβ4 significantly increased the wound healing rate of scalded rats (p < 0.01). In addition, Tβ4 treatment significantly promoted wound healing (p < 0.01) and increased the Wnt1 and β-catenin expression levels (p < 0.01). Moreover, FH535 significantly restrained the Wnt/β-catenin pathway-correlated protein levels (p < 0.01) and wound healing. </sec> <sec> <title>Conclusion:</title> Tβ4 can promote scald wound healing in rats and may play a role via evoking Wnt/β-catenin pathway activation. </sec>

Antimicrobial and Regenerative Effects of Placental Multipotent Mesenchymal Stromal Cell Secretome-Based Chitosan Gel on Infected Burns in Rats

Background: There is a need for better strategies to promote burn wound healing and prevent infection. The aim of our study was to develop an easy-to-use placental multipotent mesenchymal stromal cell (MMSC) secretome-based chitosan hydrogel (MSC-Ch-gel) and estimate its antimicrobial and regenerative activity in Staphylococcus aureus-infected burn wounds in rats. Methods: Proteomic studies of the MMSC secretome revealed proteins involved in regeneration, angiogenesis, and defence responses. The MMSC secretome was collected from cultured cells and mixed with water-soluble chitosan to prepare the placental MSC-Ch-gel, which was stored in liquid phase at 4 °C. The wounds of rats with established II-IIIa-degree burns were then infected with S. aureus and externally covered with the MSC-Ch-gel. Three additional rat groups were treated with medical Vaseline oil, the antiseptic drug Miramistin®, or the drug Bepanthen® Plus. Skin wound samples were collected 4 and 8 days after burning for further microbiological and histological analysis. Blood samples were also collected for biochemical analysis. Results: Application of the MSC-Ch-gel cleared the wound of microorganisms (S. aureus wasn’t detected in the washings from the burned areas), decreased inflammation, enhanced re-epithelialisation, and promoted the formation of well-vascularised granulation tissue. Conclusions: MSC-Ch-gel effectively promotes infected wound healing in rats with third-degree burns. Gel preparation can be easily implemented into clinical practice.

Assessing the effect of human dental pulp mesenchymal stem cell secretome on human oral, breast, and melanoma cancer cell lines

Background

The secretome of the dental pulp mesenchymal stem cells (DPMSCS-S) have an array of regenerative potential and could aid in the rehabilitation of cancer patients post-therapeutic interventions, although caution is required as DPMSC-S have shown to augment prostate cancer cells. Thus, it is vital to assess if these pro-carcinogenic effects extend to other cancer types.

Objective

To assess if DPMSC-S has any pro-carcinogenic effect on oral cancer, breast cancer, and melanoma cell lines.

Materials and methods

Conditioned media obtained from the isolated and characterized DPMSC (DPMSC-CM) were profiled using bead-based multiplex assay. AW13515 (oral cancer), MDA-MB-231 (breast cancer), and A-375 (melanoma) cell lines were exposed to 20%, 50%, and 100% DPMSC-CM for 24, 48, and 72 h. DPMSC-CM effect on the cancer cell properties and secretome were assessed.

Results

DPMSC-CM augmented invasion, adhesion, multi-drug resistance, DNA repair, and mitochondrial repair in AW13516 through upregulation of growth factors Ang-2, EGF, M−CSF, PDGF-AA, PDGF-BB, pro-inflammatory cytokines TNF-α, IL-2, downregulation of anti-inflammatory cytokine TGF-β1, and pro-inflammatory cytokine IL-4. In MDA-MB-231, invasion, and multi-drug resistance were augmented through upregulation of growth factors EGF, EPO, G-CSF, HGF, M−CSF, PDGF-AA, and pro-inflammatory cytokine TNF-α, CXCL10, IL-12p70. EMT, invasion, migration, and adhesion were augmented in A-375 through upregulation of growth factors Ang-2, EGF, PDGF-BB, TGF-α, pro-inflammatory cytokines TNF-α, and IL-17A.

Conclusion

DPMSC-CM can augment the carcinogenic properties of oral cancer, breast cancer, and melanoma cells, further animal model studies are required to validate our in-vitro findings.

Protective effect of conditioned media of human fetal dermal mesenchymal stem cells can inhibit burn-induced microvascular hyperpermeability

Burns often cause loss of skin barrier protection, fluid exudation, and local tissue edema, which hinder functional recovery. Effectively improving the quality of deep burn wound healing, shortening the wound healing time, and reducing tissue fluid leakage are urgent problems in the medical field. Human mesenchymal stem cells (MSCs) can effectively stabilize vascular endothelial injury. Fetal dermal MSCs (FDMSCs) are a newly discovered source of MSCs derived from the skin of accidentally aborted fetuses. However, the effect of FDMSCs on vascular permeability remains poorly understood. In this study, conditioned media from FDMSCs (F-CM) extracted from fetal skin tissue was prepared. The effect of F-CM on vascular permeability was evaluated using the internal circulation method FITC-dextran in vivo, and several in vitro assays, including cell viability assay, transwell permeability test, immunofluorescence, and western blotting. Altogether, our results demonstrate that F-CM could inhibit burn-induced microvascular hyperpermeability by increasing the protein expression levels of occludin and VE-cadherin, while restoring the expression of endothelial F-actin, and providing the foundation of a novel therapy for the treatment of burns with F-CM.

Mesenchymal Stem Cell Secretome for Dermatology Application: A Review

Secretome, also known as conditioned medium, is a secreted molecule from mesenchymal stem cells (MSCs) that has a variety of biological activities that can be used in various therapies, especially on the skin applications. A lack of conventional therapies makes secretome as a promising alternative therapy. The presence of growth factors, cytokines, and extracellular vesicles including microvesicles and exosomes in secretome has been widely reported, which serves in improving the proliferation and migration of cells to help in skin regeneration. Therefore, we were able to optimize the use of this secretome in a well-needed special review related to its work in addressing various skin problems. So, in this article, we discussed the benefits and biological activity of secretome on the skin application. This review was compiled based on the approval of several sites, such as Scopus, PubMed, Science Direct, and Google Scholar with the terms "MSC secretome for skin," "secretome for skin," "secretome dermatology," "secretome conditioned medium for skin," "secretome conditioned medium for skin wound," "secretome conditioned medium for aging," "secretome conditioned medium for hair growth," and "secretome conditioned medium for psoriasis." A total of 215 articles were collected for selection, of which 90 articles were used. Based on the results, it was concluded that secretome has a variety of useful activities to regenerate and repair tissue damage that have not been used on the skin, such as for wound healing, photoprotection, promotion of hair growth, psoriasis treatment, and other application as antimicrobial.

The Growth Factors and Cytokines of Dental Pulp Mesenchymal Stem Cell Secretome May Potentially Aid in Oral Cancer Proliferation

BACKGROUND

Growth factors and cytokines responsible for the regenerative potential of the dental pulp mesenchymal stem cell secretome (DPMSC-S) are implicated in oral carcinogenesis. The impact and effects of these secretory factors on cancer cells must be understood in order to ensure their safe application in cancer patients.

OBJECTIVE

We aimed to quantify the growth factors and cytokines in DPMSC-S and assess their effect on oral cancer cell proliferation.

MATERIALS AND METHODS

DPMSCs were isolated from patients with healthy teeth (n = 5) that were indicated for extraction for orthodontic reasons. The cells were characterized using flow cytometry and conditioned medium (DPMSC-CM) was prepared. DPMSC-CM was subjected to a bead-based array to quantify the growth factors and cytokines that may affect oral carcinogenesis. The effect of DPMSC-CM (20%, 50%, 100%) on the proliferation of oral cancer cells (AW123516) was evaluated using a Ki-67-based assay at 48 h. AW13516 cultured in the standard growth medium acted as the control.

RESULTS

VEGF, HCF, Ang-2, TGF-α, EPO, SCF, FGF, and PDGF-BB were the growth factors with the highest levels in the DPMSC-CM. The highest measured pro-inflammatory cytokine was TNF-α, followed by CXCL8. The most prevalent anti-inflammatory cytokine in the DPMSC-CM was IL-10, followed by TGF-β1 and IL-4. Concentrations of 50% and 100% DPMSC-CM inhibited Ki-67 expression in AW13516, although the effect was non-significant. Moreover, 20% DPMSC-CM significantly increased Ki-67 expression compared to the control.

CONCLUSIONS

The increased Ki-67 expression of oral cancer cells in response to 20% DPMSC-CM indicates the potential for cancer progression. Further research is needed to identify their effects on other carcinogenic properties, including apoptosis, stemness, migration, invasion, adhesion, and therapeutic resistance.

Stem Cell Therapy for Burns: Story so Far

Burn injuries affect approximately 11 million people annually, with fatalities amounting up to 180,000. Burn injuries constitute a global health issue associated with high morbidity and mortality. Recent years have seen advancements in regenerative medicine for burn wound healing encompassing stem cells and stem cell-derived products such as exosomes and conditioned media with promising results compared to current treatment approaches. Sources of stem cells used for treatment vary ranging from hair follicle stem cells, embryonic stem cells, umbilical cord stem cells, to mesenchymal stem cells, such as adipose-derived mesenchymal stem cells, bone marrow-derived mesenchymal stem cells, and even stem cells harvested from discarded burn tissue. Stem cells utilize various pathways for wound healing, such as PI3/AKT pathway, WNT-β catenin pathway, TGF-β pathway, Notch and Hedgehog signaling pathway. Due to the paracrine signaling mechanism of stem cells, exosomes and conditioned media derived from stem cells have also been utilized in burn wound therapy. As exosomes and conditioned media are cell-free therapy and contain various biomolecules that facilitate wound healing, they are gaining popularity as an alternative treatment strategy with significant improvement in outcomes. The treatment is provided either as direct injections or embedded in a natural/artificial scaffold. This paper reviews in detail the different sources of stem cells, stem cell-derived products, their efficacy in burn wound repair, associated signaling pathways and modes of delivery for wound healing.

Mesenchymal Stromal Cell-Conditioned Medium for Skin Diseases: A Systematic Review

The skin is the largest organ of the human body, and its dysfunction is related to many diseases. There is a need to find new potential effective therapies for some skin conditions such as inflammatory diseases, wound healing, or hair restoration. Mesenchymal stromal cell (MSC)-conditioned medium (CM) provides a potential opportunity in the treatment of skin disease. Thus, the objective of this review is to evaluate the uses of MSC-CM for treating skin diseases in both animal and human models. A systematic review was conducted regarding the use of MSC-CM for treating skin conditions. One hundred one studies were analyzed. MSC-CM was evaluated in wound healing (55), hypertrophic scars (9), flap reperfusion (4), hair restoration (15), skin rejuvenation (15), and inflammatory skin diseases (3). MSC-CM was obtained from different MSC sources, mainly adipose tissue, bone marrow, and umbilical cord blood. MSC-CM was tested intravenously, intraperitoneally, subcutaneously, intradermally or intralesionally injected or topically applied. MSC-CM was used in both animals and humans. MSC-CM improved wound healing, hair restoration, skin rejuvenation, atopic dermatitis, and psoriasis in both animals and humans. MSC-CM also decreased hypertrophic scars and flap ischemia in animal models. In conclusion, MSC-CM is a promising therapy for skin conditions. Further studies are needed to corroborate safety and effectiveness and to standardize CM manufacturing.

Development of plasma functionalized polypropylene wound dressing for betaine hydrochloride controlled drug delivery on diabetic wounds

Diabetes Mellitus is one of the most worrying issues among illnesses, and its chronic subsequences almost refer to inflammations and infections. The loading and local release of antioxidants to wounds may decrease inflammations. However, the low wettability of PolyPropylene (PP) restricts the drug from loading. So, to increase the adhesion of PP for loading an optimum amount of Betaine Hydrochloride (BET), plasma has been applied in two steps of functionalization and polymerization, which has been confirmed with FE-SEM, ATR-FTIR, and EDX. The new chemistry of the surface led to almost 80% of BET loaded. The drug-releasing ratio studied by HPLC approved the presence of a PEG-like layer, which was coated by polymerization of tetraglyme. To evaluate the wound healing potential of the application of PP meshes treated by plasma, 72 Wistar rats were subdivided into four groups. The skin injury site was removed and underwent biomechanical tests, stereological analysis, and RNA extraction. The results showed a significant improvement in the polymerized scaffold containing BET for skin injury. The present study suggests that the use of a modified PP mesh can induce tissue regeneration and accelerate wound healing at the skin injury site.

Membrane Particles Derived From Adipose Tissue Mesenchymal Stromal Cells Improve Endothelial Cell Barrier Integrity

Proinflammatory stimuli lead to endothelial injury, which results in pathologies such as cardiovascular diseases, autoimmune diseases, and contributes to alloimmune responses after organ transplantation. Both mesenchymal stromal cells (MSC) and the extracellular vesicles (EV) released by them are widely studied as regenerative therapy for the endothelium. However, for therapeutic application, the manipulation of living MSC and large-scale production of EV are major challenges. Membrane particles (MP) generated from MSC may be an alternative to the use of whole MSC or EV. MP are nanovesicles artificially generated from the membranes of MSC and possess some of the therapeutic properties of MSC. In the present study we investigated whether MP conserve the beneficial MSC effects on endothelial cell repair processes under inflammatory conditions. MP were generated by hypotonic shock and extrusion of MSC membranes. The average size of MP was 120 nm, and they showed a spherical shape. The effects of two ratios of MP (50,000; 100,000 MP per target cell) on human umbilical vein endothelial cells (HUVEC) were tested in a model of inflammation induced by TNFα. Confocal microscopy and flow cytometry showed that within 24 hours >90% of HUVEC had taken up MP. Moreover, MP ended up in the lysosomes of the HUVEC. In a co-culture system of monocytes and TNFα activated HUVEC, MP did not affect monocyte adherence to HUVEC, but reduced the transmigration of monocytes across the endothelial layer from 138 ± 61 monocytes per microscopic field in TNFα activated HUVEC to 61 ± 45 monocytes. TNFα stimulation induced a 2-fold increase in the permeability of the HUVEC monolayer measured by the translocation of FITC-dextran to the lower compartment of a transwell system. At a dose of 1:100,000 MP significantly decreased endothelial permeability (1.5-fold) respect to TNFα Stimulated HUVEC. Finally, MP enhanced the angiogenic potential of HUVEC in an in vitro Matrigel assay by stimulating the formation of angiogenic structures, such as percentage of covered area, total tube length, total branching points, total loops. In conclusion, MP show regenerative effects on endothelial cells, opening a new avenue for treatment of vascular diseases where inflammatory processes damage the endothelium.

Current Advanced Therapies Based on Human Mesenchymal Stem Cells for Skin Diseases

Skin disease may be related with immunological disorders, external aggressions, or genetic conditions. Injuries or cutaneous diseases such as wounds, burns, psoriasis, and scleroderma among others are common pathologies in dermatology, and in some cases, conventional treatments are ineffective. In recent years, advanced therapies using human mesenchymal stem cells (hMSCs) from different sources has emerged as a promising strategy for the treatment of many pathologies. Due to their properties; regenerative, immunomodulatory and differentiation capacities, they could be applied for the treatment of cutaneous diseases. In this review, a total of thirteen types of hMSCs used as advanced therapy have been analyzed, considering the last 5 years (2015-2020). The most investigated types were those isolated from umbilical cord blood (hUCB-MSCs), adipose tissue (hAT-MSCs) and bone marrow (hBM-MSCs). The most studied diseases were wounds and ulcers, burns and psoriasis. At preclinical level, in vivo studies with mice and rats were the main animal models used, and a wide range of types of hMSCs were used. Clinical studies analyzed revealed that cell therapy by intravenous administration was the advanced therapy preferred except in the case of wounds and burns where tissue engineering was also reported. Although in most of the clinical trials reviewed results have not been posted yet, safety was high and only local slight adverse events (mild nausea or abdominal pain) were reported. In terms of effectiveness, it was difficult to compare the results due to the different doses administered and variables measured, but in general, percentage of wound's size reduction was higher than 80% in wounds, Psoriasis Area and Severity Index and Severity Scoring for Atopic Dermatitis were significantly reduced, for scleroderma, parameters such as Modified Rodnan skin score (MRSC) or European Scleroderma Study Group activity index reported an improvement of the disease and for hypertrophic scars, Vancouver Scar Scale (VSS) score was decreased after applying these therapies. On balance, hMSCs used for the treatment of cutaneous diseases is a promising strategy, however, the different experimental designs and endpoints stablished in each study, makes necessary more research to find the best way to treat each patient and disease.

Antioxidative Capacity of Liver- and Adipose-Derived Mesenchymal Stem Cell-Conditioned Media and Their Applicability in Treatment of Type 2 Diabetic Rats

Type 2 diabetes mellitus (T2DM) is mainly characterized by insulin resistance and impaired insulin secretion, which cannot be reversed with existing therapeutic strategies. Using mesenchymal stem cells (MSCs), cell-based therapy has been demonstrated in displaying therapeutic effects in T2DM for their self-renewable, differentiation potential, and immunosuppressive properties and higher levels of angiogenic factors. Stem cell therapies are complicated and have a serious adverse effect including tumor formation and immunogenicity, while using mesenchymal stem cell-conditioned media (MSC-CM) significantly reduces stem cell risk, maintaining efficacy and showing significantly higher levels of growth factors, cytokines, and angiogenic factors that stimulate angiogenesis and promote fracture healing in diabetes. In the present study, we investigated the therapeutic potential of the liver and adipose MSC-CM in diabetic endothelial dysfunction compared with standard insulin therapy. Fifty adult male Sprague Dawley rats were divided equally into 5 groups as follows: control, diabetic, diabetic+insulin, diabetic+liver MSC-CM, and diabetic+adipose MSC-CM; all treatments continued for 4 weeks. Finally, we observed that liver MSC-CM therapy had the most apparent improvement in levels of blood glucose; HbA1c; AGEs; lipid panel (cholesterol, TG, LDL, HDL, and total lipids); renal function (urea, uric acid, creatinine, and total protein); liver function (AST, ALT, ALP, bilirubin, and albumin); CPK; C-peptide; HO-1; inflammatory markers including IL-6, TNF-α, and CRP; growth factors (liver and serum IGF-1); amylase; histopathological changes; pancreatic cell oxidative stress; and antioxidant markers (MDA, GSH, ROS, CAT, SOD, HO-1, and XO) toward the normal levels compared with insulin and adipose MSCs-CM. Moreover, both the liver and adipose MSC-CM relieved the hyperglycemic status by improving pancreatic islet β cell regeneration, promoting the conversion of alpha cells to beta cells, reducing insulin resistance, and protecting pancreatic tissues against oxidative stress-induced injury as well as possessing the ability to modulate immunity and angiogenesis. These results indicated that MSC-CM infusion has therapeutic effects in T2DM rats and may be a promising novel therapeutic target.

Progress of Mesenchymal Stem Cell-Derived Exosomes in Tissue Repair

Mesenchymal stem cells (MSCs) are a kind of adult stem cells with self-replication and multidirectional differentiation, which can differentiate into tissue-specific cells under physiological conditions, maintaining tissue self-renewal and physiological functions. They play a role in the pathological condition by lateral differentiation into tissue-specific cells, replacing damaged tissue cells by playing the role of a regenerative medicine , or repairing damaged tissues through angiogenesis, thereby, regulating immune responses, inflammatory responses, and inhibiting apoptosis. It has become an important seed cell for tissue repair and organ reconstruction, and cell therapy based on MSCs has been widely used clinically. The study found that the probability of stem cells migrating to the damaged area after transplantation or differentiating into damaged cells is very low, so the researchers believe the leading role of stem cell transplantation for tissue repair is paracrine secretion, secreting growth factors, cytokines or other components. Exosomes are biologically active small vesicles secreted by MSCs. Recent studies have shown that they can transfer functional proteins, RNA, microRNAs, and lncRNAs between cells, and greatly reduce the immune response. Under the premise of promoting proliferation and inhibition of apoptosis, they play a repair role in tissue damage, which is caused by a variety of diseases. In this paper, the biological characteristics of exosomes (MSCs-exosomes) derived from mesenchymal stem cells, intercellular transport mechanisms, and their research progress in the field of stem cell therapy are reviewed.

Harnessing the Secretome of Mesenchymal Stromal Cells for Traumatic Spinal Cord Injury: Multicell Comparison and Assessment of In Vivo Efficacy

Cell therapy offers significant promise for traumatic spinal cord injury (SCI), which despite many medical advances, has limited treatment strategies. Able to address the multifactorial and dynamic pathophysiology of SCI, cells present various advantages over standard pharmacological approaches. However, the use of live cells is also severely hampered by logistical and practical considerations. These include specialized equipment and expertise, standardization of cell stocks, sustained cell viability post-thawing, and cryopreservation-induced delayed-onset cell death. For this reason, we suggest a novel and clinically translatable alternative to live-cell systemic infusion, which retains the efficacy of the latter while overcoming many of its limitations. This strategy involves the administration of concentrated cell secretome and exploits the trophic mechanism by which stromal cells function. In this study, we compare the efficacy of intravenously delivered concentrated conditioned media (CM) from human umbilical cord matrix cells (HUCMCs), bone marrow mesenchymal stromal cells, as well as newborn and adult fibroblasts in a rat model of moderately severe cervical clip compression/contusion injury (C7--T1, 35 g). This is further paired with a thorough profile of the CM cytokines, chemokines, and angiogenic factors. The HUCMC-derived CM was most effective at limiting acute (48 h post-SCI) vascular pathology, specifically lesion volume, and functional vascularity. Principle component analysis (PCA), hierarchical clustering, and interaction analysis of proteins highly expressed in the HUCMC secretome suggest involvement of the MAPK/ERK, JAK/STAT, and immune cell migratory pathways. This "secretotherapeutic" strategy represents a novel and minimally invasive method to target multiple organ systems and several pathologies shortly after traumatic SCI.

Mesenchymal Stem Cell Secretome as an Emerging Cell-Free Alternative for Improving Wound Repair

The use of mesenchymal stem cells (MSC) for the treatment of cutaneous wounds is currently of enormous interest. However, the broad translation of cell therapies into clinical use is hampered by their efficacy, safety, manufacturing and cost. MSCs release a broad repertoire of trophic factors and immunomodulatory cytokines, referred to as the MSC secretome, that has considerable potential for the treatment of cutaneous wounds as a cell-free therapy. In this review, we outline the current status of MSCs as a treatment for cutaneous wounds and introduce the potential of the MSC secretome as a cell-free alternative for wound repair. We discuss the challenges and provide insights and perspectives for the future development of the MSC secretome as well as identify its potential clinical translation into a therapeutic treatment.

Engraftment of bioengineered three-dimensional scaffold from human amniotic membrane-derived extracellular matrix accelerates ischemic diabetic wound healing

Human amniotic membrane (HAM) is traditionally used for the treatment of non-healing wounds. However, high density of HAM-matrix (HAM-M) diminishes cellular contribution for successful tissue regeneration. Herein we investigated whether a bioengineered micro-porous three-dimensional (3D) HAM-scaffold (HAM-S) could promote healing in ischemic wounds in diabetic type 1 rat. HAM-S was prepared from freshly decellularized HAM. Then, 30 days after inducing diabetes, an ischemic circular excision was generated on rats' skin. The diabetic animals were randomly divided into untreated (Diabetic group), engrafted with HAM-M (D-HAM-M group) and HAM-S (D-HAM-S group). Also, non-diabeticuntreated rats (Healthy group) were considered as control. Stereological, molecular, and tensiometrical assessments were performed on post-surgical days 7, 14, and 21. We found that the volumes of new epidermis and dermis, the numerical density of epidermal basal cells and fibroblasts, the length density of blood vessels, the numbers of proliferating cells and collagen deposition as well as biomechanical properties of healed wound were significantly higher in D-HAM-S group in most cases compared those of the diabetic group, or even in some cases compared to D-HAM-M group. Furthermore, in D-HAM-S group, the transcripts for genes contributing to regeneration (Tgf-β, bFgf and Vegf) upregulated more than those of D-HAM-M group, when compared to diabetic ones. Overall, the HAM-S had more impact on delayed wound healing process compared to traditional use of intact HAM. It is therefore suggested that the bioengineered three dimensional micro-porous HAM-S is more suitable for cells adhesion, penetration, and migration for contributing to wounded tissue regeneration.

Efficacy of stem cell therapy for burn wounds: a systematic review and meta-analysis of preclinical studies

BACKGROUND

Burns remain a serious public health problem with high morbidity and mortality rates worldwide. Although there are various treatment options available, there is no consensus on the best treatment for severe burns as of yet. Stem cell therapy has a bright prospect in many preclinical studies of burn wounds. The systematic review was performed for these preclinical studies to assess the efficacy and possible mechanisms of stem cells in treating burn wounds.

METHODS

Twenty-two studies with 595 animals were identified by searching PubMed, EMBASE, Web of Science, and Cochrane Library databases from inception to 13 May 2020. In addition, a manual search of references of studies was performed to obtain potential studies. No language or time restrictions were enforced. RevMan 5.3 was used for all data analysis.

RESULTS

The overall meta-analysis showed that stem cell therapy significantly improved burn healing rate (SMD 3.06, 95% CI 1.98 to 4.14), irrespective of transplant type, burn area, and treatment method in the control group. Subgroup analyses indicated that hair follicle stem cells seemed to exert more beneficial effects on animals with burn wounds (SMD 7.53, 95% CI 3.11 to 11.95) compared with other stem cells. Furthermore, stem cell therapy seemed to exert more beneficial effects on burn wounds with second-degree (SMD 7.53, 95% CI 3.11 to 11.95) compared with third-degree (SMD 2.65, 95% CI 1.31 to 4.00).

CONCLUSIONS

Meta-analysis showed that stem cell therapy exerts a healing function for burn wounds, mainly through angiogenesis and anti-inflammatory actions. These findings also demonstrate the need for considering variations in future clinical studies using stem cells to treat a burn wound in order to maximize the effectiveness. In general, stem cells can potentially become a novel therapy candidate for burn wounds.

The Potential of a Hair Follicle Mesenchymal Stem Cell-Conditioned Medium for Wound Healing and Hair Follicle Regeneration

The study elucidated the wound healing and hair regeneration properties of a conditioned medium prepared from the culture of human hair follicle mesenchymal stem cells (HFMSCs). The wound-healing effects of mesenchymal stem cell-conditioned medium (MSC-CM) were tested in vitro using scratch assays co-cultured with HaCaT keratinocyte and monitored through optical microscopy. The cell proliferation of HFMSCs and the HaCaT keratinocyte were observed in the presence of different kinds of drugs including UK5099, sodium L-lactate, lactate dehydrogenase-A, MSC-CM, caffeine, and caffeic acid. The hair regeneration properties were investigated in vivo by administrating the MSC-CM solutions to adult B6 mouse models. For quantification, hematoxylin and eosin staining were performed following euthanasia. In vitro results revealed that MSC-CM promotes dermal cell migrations and enhances proliferation of HFMSCs and HaCaT keratinocytes, demonstrating wound-healing properties. Moreover, when the MSC-CM solutions were applied to the shaved mouse skin, a dark area that expanded overtime was seen. Although no hair growth was found, histological analysis proved that a fat layer thickness increment was found under the mouse’s skin, ultimately projecting the formation of new hair growth. MSC-CM promotes the migration and proliferation of dermal keratinocytes that are beneficial for wound healing and hair growth. It is believed that MSC-CM can potentially serve as the basis of alternative therapeutic applications for wound closure and skin regeneration as well as hair growth stimulation and hair loss prevention in alopecia.