Insights into bone marrow-derived mesenchymal stem cells safety for cutaneous repair and regeneration

Skin wound repairing effects of adipose mesenchymal stem cells is promoted by the combined application of insulin-like growth factor 1: The key role of miR-21-5p-mediated signaling transduction

Mesenchymal stem cells (ADMSCs) have been applied to the treatment of skin injuries and the co-administration of cytokines can enhance the effects. In the current study, the promoting effects of insulin-like growth factor 1 (IGF-1) on the skin wound healing effects of adipose-derived MSCs (ADMSCs) were assessed and the associated mechanism was explored by focusing on miR-21-5p mediated pathways. ADMSCs were isolated from epididymis rats, and skin wounded rats were employed as the in vivo model for evaluating the effect of ADMCs on skin healing and secretion of cytokines. Then a microarray assay was employed to select potential miR target of IGF-1 on ADMSCs. The level of the selected miR was modulated in ADMSCs, and the effects on skin injuries were also assessed. Administration of ADMSCs promoted skin wound healing and induced the production of bFGF, IL-1β, PDGF, SDF-1, IGF-1, and TNF-α. The co-administration of IGF-1 and ADMSCs strengthened the effect of ADMSCs on skin wound by suppressing activity of matrix metalloproteinase-1 (MMP-1). At molecular level, the treatment of IGF-1 up-regulated miR-21-5p level in ADMSCs, which then suppressed the expression of KLF6 in injured skin tissues and promoted wound healing. The inhibition of miR-21-5p counteracted the promoting effects of IGF-1 on the skin healing effects of ADMSCs. Findings outlined in the current study indicated that IGF-1 could promote the wound healing effects of ADMSCs by up-regulating miR-21-5p level.

Decellularized Placental Sponge Seeded with Human Mesenchymal Stem Cells Improves Deep Skin Wound Healing in the Animal Model

Skin injuries lead to a large burden of morbidity. Although numerous clinical and scientific strategies have been investigated to repair injured skin, optimal regeneration therapy still poses a considerable obstacle. To address this challenge, decellularized extracellular matrix-based scaffolds recellularized with stem cells offer significant advancements in skin regeneration and wound healing. Herein, a decellularized human placental sponge (DPS) was fabricated using the decellularization and freeze-drying technique and then recellularized with human adipose-derived mesenchymal cells (MSCs). The biological and biomechanical properties and skin full-thickness wound healing capacity of the stem cells-DPS constructs were investigated in vitro and in vivo. The DPS exhibited a uniform 3D microstructure with an interconnected pore network, 89.21% porosity, a low degradation rate, and good mechanical properties. The DPS and MSCs-DPS constructs were implanted in skin full-thickness wound models in mice. An accelerated wound healing was observed in the wounds implanted with the MSCs-DPS construct when compared to DPS and control (wounds with no treatment) during 7 and 21 days postimplantation follow-up. In the MSCs-DPS group, the wound was completely re-epithelialized, the epidermis layer was properly organized, and the dermis and epidermis' bilayer structures were restored after 7 days. Our findings suggest that DPS is an excellent carrier for MSC culture and delivery to skin wounds and now promises to proceed with clinical evaluations.

Preparation and Application of Quaternized Chitosan- and AgNPs-Base Synergistic Antibacterial Hydrogel for Burn Wound Healing

Infection is the major reason that people die from burns; however, traditional medical dressings such as gauze cannot restrain bacterial growth and enhance the healing process. Herein, an organic- and inorganic-base hydrogel with antibacterial activities was designed and prepared to treat burn wounds. Oxidized dextran (ODex) and adipic dihydrazide grafted hyaluronic acid (HA-ADH) were prepared, mixed with quaternized chitosan (HACC) and silver nanoparticles to fabricate Ag@ODex/HA-ADH/HACC hydrogel. The hydrogel, composed of nature biomaterials, has a good cytocompatibility and biodegradability. Moreover, the hydrogel has an excellent antibacterial ability and presents fast healing for burn wounds compared with commercial Ag dressings. The Ag@ODex/HA-ADH/HACC hydrogel will be a promising wound dressing to repair burn wounds and will significantly decrease the possibility of bacterial infection.

Tumor cells derived-exosomes as angiogenenic agents: possible therapeutic implications

Angiogenesis is a multistep process and various molecules are involved in regulating it. Extracellular vesicles are cell-derived particles, secreted from several types of cells and are known to mediate cell-to-cell communication. These vesicles contain different bio-molecules including nucleic acids, proteins, and lipids, which are transported between cells and regulate physiological and pathological conditions in the recipient cell. Exosomes, 30–150 nm extracellular vesicles, and their key roles in tumorigenesis via promoting angiogenesis are of great recent interest. In solid tumors, the suitable blood supply is the hallmark of their progression, growth, and metastasis, so it can be supported by angiogenesis. Tumor cells abundantly release exosomes containing different kinds of biomolecules such as angiogenic molecules that contribute to inducing angiogenesis. These exosomes can be trafficked between tumor cells or between tumor cells and endothelial cells. The protein and nucleic acid cargo of tumor derived-exosomes can deliver to endothelial cells mostly by endocytosis, and then induce angiogenesis. Tumor derived-exosomes can be used as biomarker for cancer diagnosis. Targeting exosome-induced angiogenesis may serve as a promising tool for cancer therapy. Taken together, tumor derived-exosomes are the major contributors in tumor angiogenesis and a supposed target for antiangiogenic therapies. However, further scrutiny is essential to investigate the function of exosomes in tumor angiogenesis and clinical relevance of targeting exosomes for suppressing angiogenesis.

Ultrasmall CuS@BSA nanoparticles with mild photothermal conversion synergistically induce MSCs-differentiated fibroblast and improve skin regeneration

Mesenchymal stem cell (MSC)-based therapies have been used in skin regeneration due to their ability to differentiate into many cells, promote cytokine secretion and participate in collagen deposition. In this study, we concluded that a CuS@BSA nanoparticles exhibited similar potential in inducing MSCs differentiation to fibroblasts as Cu ions for wound healing.

Methods: First, we verified the photothermal efficiency of CuS@BSA in vivo and vitro and had no cytotoxicity for MSCs when the temperature was controlled at 42 °C by adjusting the power of irradiation at 980 nm. And then we detected the expression of vimentin in MSCs, which further directed the MSCs to fibroblasts through Western blotting and Immunofluorescence when treated with CuS@BSA or pre-heat at 42 °C. In addition, we implanted MSCs into the Matrigel or electrospun PLA nanofiber membrane in vitro to evaluating the effect of heating or CuS@BSA on the morphological change of MSCs by SEM. Finally, we evaluated improving skin regeneration by the combination of preheated-MSCs and CuS@BSA nanoparticles that were encapsulated in Matrigel.

Results: The CuS@BSA nanoparticles have good photothermal conversion efficiency. Not only CuS nanoparticles itself or after irradiation at 980 nm stimulated the expressioin of vimentin in MSCs. Besides, the CuS@BSA can promote cell proliferation as Cu ion through the expression of ERK. The combination of the CuS@BSA nanoparticles and thermal treatment synergistically improved the closure of an injured wound in an injured wound model.

Conclusions: MSCs combined with CuS@BSA are a promising wound dressing for the reconstruction of full-thickness skin injuries.

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

Burn wound treatment is difficult and one of the most challenging problems in the clinic. Researchers have examined the applications of mesenchymal stem cells as a cell-based therapy for skin regeneration. But the role of human bone marrow mesenchymal stem cell conditioned medium (hBM-MSC-CM) in the treatment of burn injury remains unclear. This research aims at detecting whether hBM-MSC-CM can increase the wound healing of deep second-degree burns in male rats. In this study, 32 adult male rats per each time point were randomly divided into four groups: (1) control group, (2) sham group (DMEM), (3) common treatment group (CT), and (4) conditioned media group (CM). A 3 × 3 cm circular burn was created on the back of the rats. On postsurgical days 7, 15, and 28, the wound closure area of each wound was measured and then the skin samples were removed and analyzed using stereological methods. Wound closure area was significantly increased in the CM and CT groups on the 15th and the 28th day after burn injury compared to the control and DMEM groups. The stereological parameters and immunohistochemistry analysis of the wounds revealed significantly improved healing in the CM group compared to the control and other groups. It is concluded that these findings indicate that hBM-MSC-CM promotes skin wound healing by increasing cell proliferation, regulating collagen synthesis and collagen composition, and inducing angiogenesis at the injury site.

Effect of mesenchymal stem cells-derived exosomes on tumor microenvironment: Tumor progression versus tumor suppression

Mesenchymal stem cells (MSCs) are multipotent cells with the potential to differentiate into different cell types. Owing to their immunosuppressive and anti-inflammatory properties, they are widely used in regenerative medicine, but they have a dual effect on cancer progression and exert both growth-stimulatory or -inhibitory effects on different cancer types. It has been proposed that these controversial effects of MSC in tumor microenvironment (TME) are mediated by their polarization to proinflammatory or anti-inflammatory phenotype. In addition, they can polarize the immune system cells that in turn influence tumor progression. One of the mechanisms involved in the TME communications is extracellular vesicles (EVs). MSCs, as one of cell populations in TME, produce a large amount of EVs that can influence tumor development. Similar to MSC, MSC-EVs can exert both anti- or protumorigenic effects. In the current study, we will investigate the current knowledge related to MSC role in cancer progression with a focus on the MSC-EV content in limiting tumor growth, angiogenesis, and metastasis. We suppose MSC-EVs can be used as safe vehicles for delivering antitumor agents to TME.

The Combined Effects of Bone Marrow-Derived Mesenchymal Stem Cells and Microporous Porcine Acellular Dermal Matrices on the Regeneration of Skin Accessory Cells In Vivo

We investigated the effects of microporous porcine acellular dermal matrices (MPADM)-containing bone marrow-derived mesenchymal stem cells (BMMSCs) on accessory skin cell regeneration in vivo. Two kinds of the porcine acellular dermal matrices were prepared: one with microsized pores (the MPADM) and another without pores (the PADM). BMMSC populations from a Sprague-Dawley (SD) rat were seeded on both PADMs and MPADMs and cultured in vitro for 5 days. These rats were randomly divided into four groups: BMMSCs on an MPADM and covered with a PADM layer (group A), MPADM without cells and covered with a split-thickness skin graft (SSG) (group B), BMMSCs on an MPADM and covered with an SSG (group C), and BMMSCs on a PADM and covered with an SSG (group D). On post-surgery day (PSD) 5, all groups survived, except for group D. On PSD 7, there was no significant difference in the functional vascularization between groups A, B, and C. On PSD 14, large quantities of new capillaries, a larger rough endoplasmic reticulum in fibroblasts, and de novo unmyelinated nerve endings could be observed at the junction between the skin graft and the dermal matrix in group C; however, these structures were absent in groups A and B. The experimental results showed that MPADM could induce exogenous differentiation of BMMSCs in vivo and promote reconstruction of skin accessory cells.

The role of bone marrow mononuclear cell-conditioned medium in the proliferation and migration of human dermal fibroblasts

Background

Several recent studies have demonstrated the great potential of bone marrow cells in regenerative medicine, not only for their ability to differentiate to match a damaged cell type, but also because they synthesize and release various growth factors and cytokines.

We examined the effect of bone marrow cell-conditioned medium in the healing process, especially in terms of fibroblast proliferation and migration.

Methods

These in vitro studies consisted of co-culture (without direct contact) of dermal fibroblasts with mononuclear bone marrow cells and the use of conditioned medium obtained from these cultures in a scratch wound model.

Results

Mononuclear cells were found to increase the proliferation of fibroblasts, and the conditioned medium showed a stimulatory effect on the migration of fibroblasts.

Conclusion

When considered together with the observed increase in growth factor levels in conditioned medium, it appears that these cells act through a paracrine mechanism.

Platelet-derived growth factor and stromal cell-derived factor-1 promote the skin wound repairing effect of bone mesenchymal stem cells: a key role of matrix metalloproteinase 1 and collagens

Bone marrow mesenchymal stem cells (BMSCs) have been applied to treatment of skin wounds. In the current study, the effect of BMSCs on secretion of several cytokines during skin wound healing was investigated. In addition, the mechanism underlying the promoting effect of platelet-derived growth factor (PDGF) and stromal cell-derived factor-1 (SDF-1) on BMSCs was also preliminarily explored. BMSCs were isolated from femur and tibia of rats and characterized by surface antibodies. Skin wounded rats was employed as the in vivo model for evaluating the effect of BMSCs on skin healing and secretion of basic fibroblast growth factor (bFGF), interleukin 1β (IL-1β), PDGF, SDF-1, and tumor necrosis factor α (TNF-α). The promoting effect of SDF-1 and PDGF on the function of BMSCs was also assessed by focusing on the activity of matrix metalloproteinase 1 (MMP-1) signaling and deposition of collagens. Administration of BMSCs promoted skin wound healing and induced the production of bFGF, IL-1β, PDGF, SDF-1, and TNF-α. Moreover, PDGF treatment recruited BSMCs to injured sites and strengthened the effect of BMSCs on skin wound by suppressing activity of MMP-1. Similarly, SDF-1 treatment also increased the treating effect of BMSCs on skin injury, which was through the deposition of collagen I and collagen III. Both indicators exerted their effect on BMSCs in a dose-dependent manner. Findings outlined in the current study indicated that administration of BMSCs accelerated wound healing and enhanced the production of PDGF and SDF-1, which would contribute to recruitment of BMSCs in injured area and deposition of collagens.

Insight into Reepithelialization: How Do Mesenchymal Stem Cells Perform?

Wound reepithelialization is a cooperative multifactorial process dominated by keratinocyte migration, proliferation, and differentiation that restores the intact epidermal barrier to prevent infection and excessive moisture loss. However, in wounds that exhibit impaired wound healing, such as chronic nonhealing wounds or hypertrophic scars, the reepithelialization process has failed. Thus, it is necessary to explore a suitable way to mitigate these abnormalities to promote reepithelialization and achieve wound healing. Mesenchymal stem cells (MSCs) have the capacity for self-renewal as well as potential multipotency. These cells play important roles in many biological processes, including anti-inflammation, cell migration, proliferation, and differentiation, and signal pathway activation or inhibition. The mechanism of the involvement of MSCs in reepithelialization is still not fully understood. An abundance of evidence has shown that MSCs participate in reepithelialization by inhibiting excessive inflammatory responses, secreting important factors, differentiating into multiple skin cell types, and recruiting other host cells. This review describes the evidence for the roles that MSCs appear to play in the reepithelialization process.

Bone marrow mesenchymal stem cell aggregate: an optimal cell therapy for full-layer cutaneous wound vascularization and regeneration

Cutaneous wounds are among the most common soft tissue injuries. Wounds involving dermis suffer more from outside influence and higher risk of chronic inflammation. Therefore the appearance and function restoration has become an imperative in tissue engineering research. In this study, cell-aggregates constructed with green fluorescent protein-expressing (GFP⁺) rat bone marrow mesenchymal stem cells (BMMSCs) were applied to rat acute full-layer cutaneous wound model to confirm its pro-regeneration ability and compare its regenerative efficacy with the currently thriving subcutaneous and intravenous stem cell administration strategy, with a view to sensing the advantages, disadvantages and the mechanism behind. According to results, cell-aggregates cultured in vitro enjoyed higher expression of several pro-healing genes than adherent cultured cells. Animal experiments showed better vascularization along with more regular dermal collagen deposition for cell-aggregate transplanted models. Immunofluorescence staining on inflammatory cells indicated a shorter inflammatory phase for cell-aggregate group, which was backed up by further RT-PCR. The in situ immunofluorescence staining manifested a higher GFP⁺-cell engraftment for cell-aggregate transplanted models versus cell administered ones. Thus it is safe to say the BMMSCs aggregate could bring superior cutaneous regeneration for full layer cutaneous wound to BMMSCs administration, both intravenous and subcutaneous.

The Effect of Mesenchymal Stem Cells and Chitosan Gel on Full Thickness Skin Wound Healing in Albino Rats: Histological, Immunohistochemical and Fluorescent Study

Background

Wound healing involves the integration of complex biological processes. Several studies examined numerous approaches to enhance wound healing and to minimize its related morbidity. Both chitosan and mesenchymal stem cells (MSCs) were used in treating skin wounds. The aim of the current work was to compare MSCs versus chitosan in wound healing, evaluate the most efficient route of administration of MSCs, either intradermal or systemic injection, and elicit the mechanisms inducing epidermal and dermal cell regeneration using histological, immunohistochemical and fluorescent techniques.

Material and Methods

Forty adult male Sprague Dawley albino rats were divided into four equal groups (ten rats in each group): control group (Group I); full thickness surgical skin wound model, Group II: Wound and chitosan gel. Group III: Wound treated with systemic injection of MSCs and Group IV: Wound treated with intradermal injection of MSCs. The healing ulcer was examined on day 3, 5, 10 and 15 for gross morphological evaluation and on day 10 and 15 for histological, immunohistochemical and fluorescent studies.

Results

Chitosan was proved to promote wound healing more than the control group but none of their wound reached complete closure. Better and faster healing of wounds in MSCs treated groups were manifested more than the control or chitosan treated groups. It was found that the intradermal route of administration of stem cells enhanced the rate of healing of skin wounds better than the systemic administration to the extent that, by the end of the fifteenth day of the experiment, the wounds were completely healed in all rats of this group. Histologically, the wound areas of group IV were hardly demarcated from the adjacent normal skin and showed complete regeneration of the epidermis, dermis, hypodermis and underlying muscle fibers. Collagen fibers were arranged in many directions, with significant increase in their area percent, surrounding fully regenerated hair follicles and sebaceous glands in the dermis of the healed areas more than in other groups.

Conclusion

MSCs enhanced the healing process of wound closure more than chitosan gel treatment. Furthermore, MSCs injected intradermally, were more efficient in accelerating wound healing than any other mode of treatment.

Challenges in the Treatment of Chronic Wounds

Significance: Chronic wounds include, but are not limited, to diabetic foot ulcers, venous leg ulcers, and pressure ulcers. They are a challenge to wound care professionals and consume a great deal of healthcare resources around the globe. This review discusses the pathophysiology of complex chronic wounds and the means and modalities currently available to achieve healing in such patients. Recent Advances: Although often difficult to treat, an understanding of the underlying pathophysiology and specific attention toward managing these perturbations can often lead to successful healing. Critical Issues: Overcoming the factors that contribute to delayed healing are key components of a comprehensive approach to wound care and present the primary challenges to the treatment of chronic wounds. When wounds fail to achieve sufficient healing after 4 weeks of standard care, reassessment of underlying pathology and consideration of the need for advanced therapeutic agents should be undertaken. However, selection of an appropriate therapy is often not evidence based. Future Directions: Basic tenets of care need to be routinely followed, and a systematic evaluation of patients and their wounds will also facilitate appropriate care. Underlying pathologies, which result in the failure of these wounds to heal, differ among various types of chronic wounds. A better understanding of the differences between various types of chronic wounds at the molecular and cellular levels should improve our treatment approaches, leading to better healing rates, and facilitate the development of new more effective therapies. More evidence for the efficacy of current and future advanced wound therapies is required for their appropriate use.

Mesenchymal Stem Cell Exosomes Induce Proliferation and Migration of Normal and Chronic Wound Fibroblasts, and Enhance Angiogenesis In Vitro

Although chronic wounds are common and continue to be a major cause of morbidity and mortality, treatments for these conditions are lacking and often ineffective. A large body of evidence exists demonstrating the therapeutic potential of mesenchymal stem cells (MSCs) for repair and regeneration of damaged tissue, including acceleration of cutaneous wound healing. However, the exact mechanisms of wound healing mediated by MSCs are unclear. In this study, we examined the role of MSC exosomes in wound healing. We found that MSC exosomes ranged from 30 to 100-nm in diameter and internalization of MSC exosomes resulted in a dose-dependent enhancement of proliferation and migration of fibroblasts derived from normal donors and chronic wound patients. Uptake of MSC exosomes by human umbilical vein endothelial cells also resulted in dose-dependent increases of tube formation by endothelial cells. MSC exosomes were found to activate several signaling pathways important in wound healing (Akt, ERK, and STAT3) and induce the expression of a number of growth factors [hepatocyte growth factor (HGF), insulin-like growth factor-1 (IGF1), nerve growth factor (NGF), and stromal-derived growth factor-1 (SDF1)]. These findings represent a promising opportunity to gain insight into how MSCs may mediate wound healing.

MSCs seeded on bioengineered scaffolds improve skin wound healing in rats

Growing evidence has shown the promise of mesenchymal stromal cells (MSCs) for the treatment of cutaneous wound healing. We have previously demonstrated that MSCs seeded on an artificial dermal matrix, Integra (Integra Lifesciences Corp., Plainsboro, NJ) enriched with platelet-rich plasma (Ematrix) have enhanced proliferative potential in vitro as compared with those cultured on the scaffold alone. In this study, we extended the experimentation by evaluating the efficacy of the MSCs seeded scaffolds in the healing of skin wounds in an animal model in vivo. It was found that the presence of MSCs within the scaffolds greatly ameliorated the quality of regenerated skin, reduced collagen deposition, enhanced reepithelization, increased neo-angiogenesis, and promoted a greater return of hair follicles and sebaceous glands. The mechanisms involved in these beneficial effects were likely related to the ability of MSCs to release paracrine factors modulating the wound healing response. MSC-seeded scaffolds, in fact, up-regulated matrix metalloproteinase 9 expression in the extracellular matrix and enhanced the recruitment of endogenous progenitors during tissue repair. In conclusion, the results of this study provide evidence that the treatment with MSC-seeded scaffolds of cutaneous wounds contributes to the recreation of a suitable microenvironment for promoting tissue repair/regeneration at the implantation sites.

Effect of bone marrow derived mesenchymal stem cells on healing of induced full-thickness skin wounds in albino rat

BACKGROUND AND OBJECTIVES

Mesenchymal stem cells have delivered new approaches to the management of wound healing in severe skin injuries. This work was planned to evaluate the effect of bone marrow-derived mesenchymal stem cells (BMSCs) on healing of induced full thickness skin wounds in albino rats using topical & systemic injections.

METHODS AND RESULTS

Forty adult male albino rats were classified into 2 groups after induction of full thickness skin wound; untreated group and stem cell-treated group. The latter was further subdivided into topically and systemically treated ones. BMSCs were isolated & labeled by PKH26 before injection. Healing of wounds was evaluated grossly. Skin biopsies were obtained one & three weeks after wound induction. Sections were stained with Hematoxylin & Eosin, Masson's trichrome and immunohistochemichal stain for vascular endothelial growth factor (VEGF). Epidermal thicknesses and mean area percent of both collagen fibers & VEGF immunopositive cells were measured using image analyzer & results were subjected to statistical analysis. PKH26 fluorescent-labeled cells were found in the regenerated epidermis, hair follicles and dermis in BMSCs-treated groups. By the end of the third week, the wounds of BMSCs-treated groups showed full regeneration of epidermis, re-organization of collagen and decrease in VEGF immunopositive cells. Delayed wound healing was seen in 20% of systemically treated rats. Significant increase in the mean area percent of collagen fibers was detected in topically treated group.

CONCLUSIONS

Both methods of BMSCs injection were effective in healing of full thickness skin wound but topical method was more effective.

The emerging use of bone marrow-derived mesenchymal stem cells in the treatment of human chronic wounds

INTRODUCTION

Close to 5 million people in the USA are affected by chronic wounds, and billions of dollars are spent annually for their treatment. Despite advances in chronic wound management over the past decades, many patients afflicted with chronic wounds fail to heal or their ulcers recur. There is emerging evidence that the use of bone marrow-derived mesenchymal stem cells (BM-MSCs) can offset this situation of impaired healing.

AREAS COVERED

This article provides a review of the use of BM-MSC for the treatment of chronic wounds, the current development of stem cell delivery to chronic wounds and related challenges are also described in this manuscript.

EXPERT OPINION

Numerous animal studies and a few pilot studies in human wounds have shown that BM-MSC can augment wound closure. Still, the primary contribution of mesenchymal stem cells (MSCs) to cutaneous regeneration and the long-term systemic effects of MSCs are yet to be established. In addition, we need to determine whether other types of stem/progenitor cells will be more effective. Therefore, more randomized controlled clinical trials need to be undertaken. It is of importance to remember that even with the most advanced and sophisticated therapeutic approaches, proper wound care and adherence to basic principles remain critical.