Role of whole bone marrow, whole bone marrow cultured cells, and mesenchymal stem cells in chronic wound healing

Exosomes in nanomedicine: a promising cell-free therapeutic intervention in burn wounds

Burn injuries are serious injuries that have a big impact on a person's health and can even cause death. Incurring severe burns can incite an immune response and inflammation within the body, alongside metabolic changes. It is of utmost importance to grasp the fact that the effects of the burn injury extend beyond the body, affecting the mind and overall well-being. Burn injuries cause long-lasting changes that need to be taken care of in order to improve their quality of life. The intricate process of skin regeneration at the site of a burn wound involves a complex and dynamic interplay among diverse cells, growth factors, nerves, and blood vessels. Exciting opportunities have arisen in the field of stem cells and regenerative medicine, allowing us to explore the development of cell-free-based alternatives that can aid in the treatment of burn injuries. These cell-free-based therapies have emerged as a promising facet within regenerative medicine. Exosomes, also referred to as naturally occurring nanoparticles, are small endosome-derived vesicles that facilitate the delivery of molecular cargo between the cells, thus allowing intercellular communication. The knowledge gained in this field has continued to support their therapeutic potential, particularly in the domains of wound healing and tissue regeneration. Notably, exosomes derived from mesenchymal stem cells (MSCs) can be safely administered in the system, which is then adeptly uptaken and internalized by fibroblasts/epithelial cells, subsequently accelerating essential processes such as migration, proliferation, and collagen synthesis. Furthermore, exosomes released by immune cells, specifically macrophages, possess the capability to modulate inflammation and effectively diminish it in adjacent cells. Exosomes also act as carriers when integrated with a scaffold, leading to scarless healing of cutaneous wounds. This comprehensive review examines the role of exosomes in burn wound healing and their potential utility in regeneration and repair.

Evolution and Innovations in Bone Marrow Cellular Therapy for Musculoskeletal Disorders: Tracing the Historical Trajectory and Contemporary Advances

Bone marrow cellular therapy has undergone a remarkable evolution, significantly impacting the treatment of musculoskeletal disorders. This review traces the historical trajectory from early mythological references to contemporary scientific advancements. The groundbreaking work of Friedenstein in 1968, identifying fibroblast colony-forming cells in bone marrow, laid the foundation for future studies. Caplan's subsequent identification of mesenchymal stem cells (MSCs) in 1991 highlighted their differentiation potential and immunomodulatory properties, establishing them as key players in regenerative medicine. Contemporary research has focused on refining techniques for isolating and applying bone marrow-derived MSCs. These cells have shown promise in treating conditions like osteonecrosis, osteoarthritis, and tendon injuries thanks to their ability to promote tissue repair, modulate immune responses, and enhance angiogenesis. Clinical studies have demonstrated significant improvements in pain relief, functional recovery, and tissue regeneration. Innovations such as the ACH classification system and advancements in bone marrow aspiration methods have standardized practices, improving the consistency and efficacy of these therapies. Recent clinical trials have validated the therapeutic potential of bone marrow-derived products, highlighting their advantages in both surgical and non-surgical applications. Studies have shown that MSCs can reduce inflammation, support bone healing, and enhance cartilage repair. However, challenges remain, including the need for rigorous characterization of cell populations and standardized reporting in clinical trials. Addressing these issues is crucial for advancing the field and ensuring the reliable application of these therapies. Looking ahead, future research should focus on integrating bone marrow-derived products with other regenerative techniques and exploring non-surgical interventions. The continued innovation and refinement of these therapies hold promise for revolutionizing the treatment of musculoskeletal disorders, offering improved patient outcomes, and advancing the boundaries of medical science.

Phenotypic and Functional Outcomes in Macrophages Exposed to an Environmentally Relevant Mixture of Organophosphate Esters in Vitro

BACKGROUND

Organophosphate esters (OPEs) are flame retardants and plasticizers used in consumer products. OPEs are found ubiquitously throughout the environment with high concentrations in indoor house dust. Exposure to individual OPEs is associated with immune dysfunction, particularly in macrophages. However, OPEs exist as complex mixtures and the effects of environmentally relevant mixtures on the immune system have not been investigated.

OBJECTIVES

The objectives of this study were to evaluate the toxicity of an environmentally relevant mixture of OPEs that models Canadian house dust on macrophages using phenotypic and functional assessments in vitro.

METHODS

High-content live-cell fluorescent imaging for phenotypic biomarkers of toxicity in THP-1 macrophages treated with the OPE mixture was undertaken. We used confocal microscopy and cholesterol analysis to validate and expand on the observed OPE-induced lipid phenotype. Then, we used flow cytometry and live-cell imaging to conduct functional tests and uncover mechanisms of OPE-induced phagocytic suppression. Finally, we validated our THP-1 findings in human primary peripheral blood mononuclear cells (hPBMC) derived macrophages.

RESULTS

Exposure to non-cytotoxic dilutions of the OPE mixture resulted in higher oxidative stress and disrupted lysosome and lipid homeostasis in THP-1 and primary macrophages. We further observed that phagocytosis of apoptotic cells in THP-1 and primary macrophages was lower in OPE-exposed cells vs. controls. In THP-1 macrophages, phagocytosis of both Gram-positive and Gram-negative bacteria was also lower in OPE-exposed cells vs. controls. Additionally, the OPE mixture altered the expression of phagocytic receptors linked to the recognition of phosphatidylserine and pathogen-associated molecular patterns.

DISCUSSION

The results of this in vitro study suggested that exposure to an environmentally relevant mixture of OPEs resulted in higher lipid retention in macrophages and poor efferocytic response. These effects could translate to enhanced foam cell generation resulting in higher cardiovascular mortality. Furthermore, bacterial phagocytosis was lower in OPE-exposed macrophages in an in vitro setting, which may indicate the potential for reduced bacterial clearance in models of infections. Taken together, our data provide strong evidence that mixtures of OPEs can influence the biology of macrophages and offer new mechanistic insights into the impact of OPE mixtures on the immune system. https://doi.org/10.1289/EHP13869.

Orchestration of Macrophage Polarization Dynamics by Fibroblast-Secreted Exosomes during Skin Wound Healing

Macrophages undertake pivotal yet dichotomous functions during skin wound healing, mediating both early proinflammatory immune activation and late anti-inflammatory tissue remodeling processes. The timely phenotypic transition of macrophages from inflammatory M1 to proresolving M2 activation states is essential for efficient healing. However, the endogenous mechanisms calibrating macrophage polarization in accordance with the evolving tissue milieu remain undefined. In this study, we reveal an indispensable immunomodulatory role for fibroblast-secreted exosomes in directing macrophage activation dynamics. Fibroblast-derived exosomes permitted spatiotemporal coordination of macrophage phenotypes independent of direct intercellular contact. Exosomes enhanced macrophage sensitivity to both M1 and M2 polarizing stimuli, yet they also accelerated timely switching from M1 to M2 phenotypes. Exosome inhibition dysregulated macrophage responses, resulting in aberrant inflammation and impaired healing, whereas provision of exogenous fibroblast-derived exosomes corrected defects. Topical application of fibroblast-derived exosomes onto chronic diabetic wounds normalized dysregulated macrophage activation to resolve inflammation and restore productive healing. Our findings elucidate fibroblast-secreted exosomes as remote programmers of macrophage polarization that calibrate immunological transitions essential for tissue repair. Harnessing exosomes represents a previously unreported approach to steer productive macrophage activation states with immense therapeutic potential for promoting healing in chronic inflammatory disorders.

Transplantation of Bone Marrow Cells Preactivated With Sodium Nitroprusside Improves Acute Wound Healing in Rabbits

The development of wound healing impairment mainly represents challenging clinical problems. The less and high concentrations of nitric oxide can influence angiogenesis, remodeling, and proliferation of skin cells. Delayed acute wounds generally have failed to progress via the normal stages of healing. Such wounds usually enter a state of pathological inflammation due to a postponed, incomplete, and uncoordinated healing process. This study aimed to investigate the effect of normal bone marrow cells (BMCs) and preconditioning of BMCs with minimum concentrations of sodium nitroprusside (NaNP) solution for acute wound healing. For acute wound healing, full-thickness dorsal wounds were created on rabbits. The acute wound of rabbits was treated with BMCs and preactivated BMCs with NaNP. Histological results showed that BMCs preactivated with NaNP could improve collagen deposition, enhanced reepithelization, and decreased inflammatory infiltration. Overall, BMCs treated with NaNP can help to improve acute wound healing in rabbits. The result strongly confirmed the beneficial effect in augmenting the wound healing process. The combination of BMCs with NaNP was safe and convenient for acute wound healing.

Mesodermal Derivatives of Pluripotent Stem Cells Route to Scarless Healing

Scar formation during normal tissue regeneration in adults may result in noticeable cosmetic and functional defects and have a significant impact on the quality of life. In contrast, fetal tissues in the mid-gestation period are known to be capable of complete regeneration with the restitution of the initial architecture, organization, and functional activity. Successful treatments that are targeted to minimize scarring can be realized by understanding the cellular and molecular mechanisms of fetal wound regeneration. However, such experiments are limited by the inaccessibility of fetal material for comparable studies. For this reason, the molecular mechanisms of fetal regeneration remain unknown. Mesenchymal stromal cells (MSCs) are central to tissue repair because the molecules they secrete are involved in the regulation of inflammation, angiogenesis, and remodeling of the extracellular matrix. The mesodermal differentiation of human pluripotent stem cells (hPSCs) recapitulates the sequential steps of embryogenesis in vitro and provides the opportunity to generate the isogenic cell models of MSCs corresponding to different stages of human development. Further investigation of the functional activity of cells from stromal differon in a pro-inflammatory microenvironment will procure the molecular tools to better understand the fundamental mechanisms of fetal tissue regeneration. Herein, we review recent advances in the generation of clonal precursors of primitive mesoderm cells and MSCs from hPSCs and discuss critical factors that determine the functional activity of MSCs-like cells in a pro-inflammatory microenvironment in order to identify therapeutic targets for minimizing scarring.

Current research on fungi in chronic wounds

The occurrence of chronic wounds is a major global health issue. These wounds are difficult to heal as a result of disordered healing mechanisms. The most common types of chronic wounds are diabetic ulcers, pressure ulcers, arterial/venous ulcers and nonhealing surgical wounds. Although bacteria are an important cause of chronic nonhealing wounds, fungi also play a substantial role in them. The fungal infection rate varies with different chronic wound types, but overall, the prevalence of fungi is extremely underestimated in the clinical treatment and management of chronic wounds. Wounds and ulcers can be colonized by host cutaneous, commensal or environmental fungi and evolve into local infections, causing fungemia as well as invasive fungal disease. Furthermore, the fungi involved in nonhealing wound-related infections help commensal bacteria resist antibiotics and the host immune response, forcing wounds to become reservoirs for multiresistant species, which are considered a potential key factor in the microbial bioburden of wounds and ulcers. Fungi can be recalcitrant to the healing process. Biofilm establishment is the predominant mechanism of fungal resistance or tolerance to antimicrobials in chronic nonhealing wounds. Candida albicans yeast and Trichophyton rubrum filamentous fungi are the main fungi involved in chronic wound infection. Fungal species diversity and drug resistance phenotypes in different chronic nonhealing wound types will be emphasized. In this review, we outline the latest research on fungi in chronic wounds and discuss challenges and future perspectives related to diagnosing and managing chronic wounds.

Native and engineered extracellular vesicles for wound healing

Extracellular vesicles (EVs) that act as messengers mediate communication between parent and recipient cells through their contents, including nucleic acids, proteins, and lipids. These endogenous vesicles have emerged as a novel cell-free strategy for the treatment of diseases. EVs can be released by various types of cells with unique biological properties. Recent studies have shown that native EVs are used as therapeutic agents to promote tissue repair by delivering various growth factors and trophic factors including VEGF, EGF, TFN-α, IL-1β, and TGF-β to participate in all physiological processes of wound healing. Furthermore, to improve their specificity, safety, and efficiency for wound healing, the content and surface of EVs can be designed, modified, and engineered. The engineering strategies of EVs are divided into parent cell modification and indirect modification of EVs. The therapeutic potential of current EVs and engineered EVs for wound healing still requires the exploration of their large-scale clinical applications through innovative approaches. Herein, we provide an overview of the current biological knowledge about wound healing and EVs, as well as the application of native EVs in promoting wound healing. We also outline recent advances in engineering EV methodologies to achieve ideal therapeutic potential. Finally, the therapeutic applications of engineered EVs in wound healing are reviewed, and the challenges and prospects for the translation of engineered EVs to clinical applications are discussed.

Wound Healing and Antioxidant Properties of Launaea procumbens Supported by Metabolomic Profiling and Molecular Docking

Wounds adversely affect people’s quality of life and have psychological, social, and economic impacts. Herbal remedies of Launaea procumbens (LP) are used to treat wounds. In an excision wound model, topical application of LP significantly promoted wound closure (on day 14, LP-treated animals had the highest percentages of wound closure in comparison with the other groups, as the wound was entirely closed with a closure percentage of 100%, p < 0.05). Histological analysis revealed a considerable rise in the number of fibroblasts, the amount of collagen, and its cross-linking in LP-treated wounds. Gene expression patterns showed significant elevation of TGF-β levels (2.1-fold change after 7 days treatment and 2.7-fold change in 14 days treatment) and downregulation of the inflammatory TNF-α and IL-1β levels in LP-treated wounds. Regarding in vitro antioxidant activity, LP extract significantly diminished the formation of H2O2 radical (IC50 = 171.6 μg/mL) and scavenged the superoxide radical (IC50 of 286.7 µg/mL), indicating antioxidant potential in a dose-dependent manner. Dereplication of the secondary metabolites using LC-HRMS resulted in the annotation of 16 metabolites. The identified compounds were docked against important wound-healing targets, including vascular endothelial growth factor (VEGF), collagen α-1, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and transforming growth factor-β (TGF-β). Among dereplicated compounds, luteolin 8-C-glucoside (orientin) demonstrated binding potential to four investigated targets (VEGF, interleukin 1β, TNF-α, and collagen α-1). To conclude, Launaea procumbens extract could be regarded as a promising topical therapy to promote wound healing in excisional wounds, and luteolin 8-C-glucoside (orientin), one of its constituents, is a potential wound-healing drug lead.

The Potential of Corchorus olitorius Seeds Buccal Films for Treatment of Recurrent Minor Aphthous Ulcerations in Human Volunteers

Aphthous ulcers are very common disorders among different age groups and are very noxious and painful. The incidence of aphthous ulcer recurrence is very high and it may even last for a maximum of 6 days and usually, patients cannot stand its pain. This study aims to prepare a buccoadhesive fast dissolving film containing Corchorus olitorius seed extract to treat recurrent minor aphthous ulceration (RMAU) in addition to clinical experiments on human volunteers. An excision wound model was used to assess the in vivo wound healing potential of Corchorus olitorius L. seed extract, with a focus on wound healing molecular targets such as TGF-, TNF-, and IL-1. In addition, metabolomic profiling using HR-LCMS for the crude extract of Corchorus olitorius seeds was explored. Moreover, molecular docking experiments were performed to elucidate the binding confirmation of the isolated compounds with three molecular targets (TNF-α, IL-1β, and GSK3). Additionally, the in vitro antioxidant potential of C. olitorius seed extract using both H2O2 and superoxide radical scavenging activity was examined. Clinical experiments on human volunteers revealed the efficiency of the prepared C. olitorius seeds buccal fast dissolving film (CoBFDF) in relieving pain and wound healing of RMAU. Moreover, the wound healing results revealed that C. olitorius seed extract enhanced wound closure rates (p ≤ 0.001), elevated TGF-β levels and significantly downregulated TNF-α and IL-1β in comparison to the Mebo-treated group. The phenotypical results were supported by biochemical and histopathological findings, while metabolomic profiling using HR-LCMS for the crude extract of Corchorus olitorius seeds yielded a total of 21 compounds belonging to diverse chemical classes. Finally, this study highlights the potential of C. olitorius seed extract in wound repair uncovering the most probable mechanisms of action using in silico analysis.

Wound Healing and Antioxidant Capabilities of Zizyphus mauritiana Fruits: In-Vitro, In-Vivo, and Molecular Modeling Study

LC-HRMS-assisted chemical profiling of Zizyphus mauritiana fruit extract (ZFE) led to the dereplication of 28 metabolites. Furthermore, wound healing activity of ZFE in 24 adult male New Zealand Dutch strain albino rabbits was investigated in-vivo supported by histopathological investigation. Additionally, the molecular mechanism was studied through different in-vitro investigations as well as, studying both relative gene expression and relative protein expression patterns. Moreover, the antioxidant activity of ZFE extract was examined using two in-vitro assays including hydrogen peroxide and superoxide radical scavenging activities that showed promising antioxidant potential. Topical application of the extract on excision wounds showed a significant increase in the wound healing rate (p < 0.001) in comparison to the untreated and MEBO®-treated groups, enhancing TGF-β1, VEGF, Type I collagen expression, and suppressing inflammatory markers (TNF-α and IL-1β). Moreover, an in silico molecular docking against TNFα, TGFBR1, and IL-1β showed that some of the molecules identified in ZFE can bind to the three wound-healing related protein actives sites. Additionally, PASS computational calculation of antioxidant activity revealed potential activity of three phenolic compounds (Pa score > 0.5). Consequently, ZFE may be a potential alternative medication helping wound healing owing to its antioxidant and anti-inflammatory activities.

Antioxidant and Wound Healing Potential of Vitis vinifera Seeds Supported by Phytochemical Characterization and Docking Studies

This study explored the in vivo wound healing potential of Vitis vinifera seed extract using an excision wound model with focus on wound healing molecular targets including TGFBR1, VEGF, TNF-α, and IL-1β. The wound healing results revealed that V. vinifera seed extract enhanced wound closure rates (p < 0.001), elevated TGF-β and VEGF levels, and significantly downregulated TNF-α and IL-1β levels in comparison to the Mebo®-treated group. The phenotypical results were supported by biochemical and histopathological findings. Phytochemical investigation yielded a total of 36 compounds including twenty-seven compounds (1−27) identified from seed oil using GC-MS analysis, along with nine isolated compounds. Among the isolated compounds, one new benzofuran dimer (28) along with eight known ones (29−36) were identified. The structure of new compound was elucidated utilizing 1D/2D NMR, with HRESIMS analyses. Moreover, molecular docking experiments were performed to elucidate the molecular targets (TNF-α, TGFBR1, and IL-1β) of the observed wound healing activity. Additionally, the in vitro antioxidant activity of V. vinifera seed extract along with two isolated compounds (ursolic acid 34, and β-sitosterol-3-O-glucopyranoside 36) were explored. Our study highlights the potential of V. vinifera seed extract in wound repair uncovering the most probable mechanisms of action using in silico analysis.

Umbilical Cord-Derived Mesenchymal Stem Cells Improve TGF-β, α-SMA and Collagen on Erectile Dysfunction in Streptozotocin-Induced Diabetic Rats

Background

A Erectile dysfunction (ED) is one of the well-known comorbidities in males with diabetes mellitus (DM), whose pathogenesis might be induced by dysregulation of corpus cavernosum smooth muscle cells. UC-MSCs are multipotent cells that attract considerable interest due to immunoregulatory properties and might be a potential strategy to regulate and recover the functional cells and tissues, including tissue improvement in DMED.

Objective

This study aims to determine the efficacy of UC-MSCs in improving the erectile function of DMED rats through analyzing the expression of TGF-β, α-SMA, and collagen.

Methods

Total number of 30 male Sprague-Dawley rats (6 to 8 weeks old) were randomly divided into four groups (negative control group, positive control group, T1 group, and T2 group). After 16 h fast, 24 rats were randomly selected and intraperitoneally injected with streptozotocin to induce DM. At 8 weeks after STZ injection, rats with DMED were identified by unresponsive erectile stimulation within 30 min. PC group received 500 μL; T1 rats treated with 500 μL PBS containing 1x106 UC-MSCs; T2 rats treated with 500 μL PBS containing 3x106 UC-MSCs. After MSCs treatment, the rats were sacrificed and the corpus cavernosum tissues were prepared for histological observations.

Results

This study resulted in the administration of UC-MSCs could downregulate the expression of TGF-β, α-SMA, and collagen leading to the improvement of DMED.

Conclusion

UC-MSCs improve the expression of TGF-β, α-SMA, and collagen on erectile dysfunction in streptozotocin-induced diabetic rats.

Wound Healing Metabolites from Peters' Elephant-Nose Fish Oil: An In Vivo Investigation Supported by In Vitro and In Silico Studies

Gnathonemuspetersii (F. Mormyridae) commonly known as Peters' elephant-nose fish is a freshwater elephant fish native to West and Central African rivers. The present research aimed at metabolic profiling of its derived crude oil via GC-MS analysis. In addition, wound healing aptitude in adult male New Zealand Dutch strain albino rabbits along with isolated bioactive compounds in comparison with a commercial product (Mebo^®). The molecular mechanism was studied through a number of in vitro investigations, i.e., radical scavenging and inhibition of COX enzymes, in addition to in silico molecular docking study. The results revealed a total of 35 identified (71.11%) compounds in the fish oil, belonging to fatty acids (59.57%), sterols (6.11%), and alkanes (5.43%). Phytochemical investigation of the crude oil afforded isolation of six compounds 1-6. Moreover, the crude oil showed significant in vitro hydrogen peroxide and superoxide radical scavenging activities. Furthermore, the crude oil along with one of its major components (compound 4) exhibited selective inhibitory activity towards COX-2 with IC₅₀ values of 15.27 and 2.41 µM, respectively. Topical application of the crude oil on excision wounds showed a significant (p < 0.05) increase in the wound healing rate in comparison to the untreated and Mebo^®-treated groups, where fish oil increased the TGF-β1 expression, down-regulated TNF-α, and IL-1β. Accordingly, Peters' elephant-nose fish oil may be a potential alternative medication helping wound healing owing to its antioxidant and anti-inflammatory activities.

Improvement of Chronic Wound Healing by Pre-activated Bone Marrow Cells with Sodium Nitroprusside in Rabbits

AIM OF STUDY

This study investigated whether pre-activated bone marrow cells with sodium nitro prusside have effectiveness in the inhibition of diabetic wound healing in diabetic rabbits. In diabetic skin disorders and conditions involved redox state disturbances. The aim was to determine the effect of two minimum dosages of sodium nitro prusside, and its' potential with bone marrow cells for chronic wound healing in-vivo.

METHODS

Full-thickness skin dorsal wounds were created on diabetic rabbits. The effects of two minimum concentrations of sodium nitro prusside solution with bone marrow cells on wound healing were studied. The useful combination of sodium nitro prusside with bone marrow cells on wound repair may be attributed to its functional influences on inflammation, angiogenesis, cell proliferation, matrix deposition, and remodeling.

RESULTS

The in-vivo experiments confirmed that pre-activated bone marrow cells contributed to wound healing by alleviating oxidative stress, increasing proliferation and migration, decreasing apoptosis. In histological results, improved collagen deposition, enhanced re-epithelization, angiogenesis, and decreased inflammatory infiltration were also detected in wound biopsies.

CONCLUSIONS

For the treatment of chronic wounds, cell-based therapy was an attractive approach. Bone marrow cells have a low ability to differentiate various types of cells or late healing without pretreatment. So it was needed to increase their potency of differentiation. The transplantation of pretreated bone marrow cells with a prime quantity of sodium nitro prusside solution improved chronic wound healing with a greater level of growth factors and a minimum level of oxidative stress.

Intralesional allogeneic adipose-derived stem cells application in chronic diabetic foot ulcer: Phase I/2 safety study

BACKGROUND

Impaired wound healing is a major cause of morbidity in diabetic patients by causing chronic ulcers. This study aimed to investigate the safety and outcomes after intralesional allogeneic adipose-derived mesenchymal stem cells injection in chronic diabetic foot ulcers.

METHODS

Twenty patients (12 male and eight female) were involved in the study. We randomized the patients into two groups of 10 patients each. The study group was treated with allogeneic adipose-derived mesenchymal stem cells injection with standard diabetic wound care. The control group received only standard diabetic wound care. Patient demographics, wound characteristics, wound closure time, amputation rates and clinical scores were evaluated.

RESULTS

The mean age was 57.3 ± 6.6 years. The mean follow-up duration was 48.0 (range, 26-50) months. Wound closure was achieved in 17 of 20 lesions (study group, 9 lesions; control group, 8 lesions; respectively). The mean time to wound closure was 31.0 ± 10.7 (range, 22-55) days in the study group, 54.8 + 15.0 (range, 30-78) days in the control group (p = 0.002). In three patients, minor amputations were performed (one patient in study group; two patients in the control group, p = 0.531). There was a significant difference between groups in terms of postoperative Short Form 36- physical functioning (p = 0.017) and Short Form 36-general health (p = 0.010).

CONCLUSION

Allogeneic adipose-derived mesenchymal stem cells injection was found to be a safe and effective method with a positive contribution to wound-healing time in the treatment of chronic diabetic foot ulcers.

Transplanted Antler Stem Cells Stimulated Regenerative Healing of Radiation-induced Cutaneous Wounds in Rats

Radiation-induced cutaneous injury is the main side effect of radiotherapy. The injury is difficult to cure and the pathogenesis is complex. Mesenchymal stem cells (MSCs) serve as a promising candidate for cell-based therapy for the treatment of cutaneous wounds. The aim of the present study was to investigate whether antler stem cells (AnSCs) have better therapeutic effects on radiation-induced cutaneous injury than currently available ones. In this study, a rat model of cutaneous wound injury from Sr-90 radiation was used. AnSCs (1 × 10⁶/500 μl) were injected through the tail vein on the first day of irradiation. Our results showed that compared to the control group, AnSC-treated rats exhibited a delayed onset (14 days versus 7 days), shorter recovery time (51 days versus 84 days), faster healing rate (100% versus 70% on day 71), and higher healing quality with more cutaneous appendages regenerated (21:10:7/per given area compared to those of rat and human MSCs, respectively). More importantly, AnSCs promoted much higher quality of healing compared to other types of stem cells, with negligible scar formation. AnSC lineage tracing results showed that the injected-dye-stained AnSCs were substantially engrafted in the wound healing tissue, indicating that the therapeutic effects of AnSCs on wound healing at least partially through direct participation in the wound healing. Expression profiling of the wound-healing-related genes in the healing tissue of AnSC group more resembled a fetal wound healing. Revealing the mechanism underlying this higher quality of wound healing by using AnSC treatment would help to devise more effective cell-based therapeutics for radiation-induced wound healing in clinics.

CCR2-engineered mesenchymal stromal cells accelerate diabetic wound healing by restoring immunological homeostasis

Impaired wound healing presents great health risks to patients. While encouraging, the current clinical successes of mesenchymal stromal cell (MSC)-based therapies for tissue repair have been limited. Genetic engineering could endow MSCs with more robust regenerative capacities. Here, we identified that C-C motif chemokine receptor 2 (CCR2) overexpression enhanced the targeted migration and immunoregulatory potential of MSCs in response to C-C motif chemokine ligand 2 (CCL2) in vitro. Intravenously infusion of CCR2-engineered MSCs (MSCs^CCR2) exhibited improved homing efficiencies to injured sites and lungs of diabetic mice. Accordingly, MSC^CCR2 infusion inhibited monocyte infiltration, reshaped macrophage inflammatory properties, prompted the accumulation of regulatory T cells (Treg cells) in injured sites, and reshaped systemic immune responses via the lung and spleen in mouse diabetic wound models. In summary, CCR2-engineered MSCs restore immunological homeostasis to accelerate diabetic wound healing via their improved homing and immunoregulatory potentials in response to CCL2. Therefore, these findings provide a novel strategy to explore genetically engineered MSCs as tools to facilitate tissue repair in diabetic wounds.

Therapeutic effect of mesenchymal stem cells on histopathological, immunohistochemical, and molecular analysis in second-grade burn model

Background and aim

Deleterious cutaneous tissue damages could result from exposure to thermal trauma, which could be ameliorated structurally and functionally through therapy via the most multipotent progenitor bone marrow mesenchymal stem cells (BM-MSCs). This study aimed to induce burns and examine the effect of BM-MSCs during a short and long period of therapy.

Material and methods

Ninety albino rats were divided into three groups: group I (control); group II (burn model), the animals were exposed to the preheated aluminum bar at 100°C for 15 s; and group III (the burned animals subcutaneously injected with BM-MSCs (2×10⁶ cells/ ml)); they were clinically observed and sacrificed at different short and long time intervals, and skin samples were collected for histopathological and immunohistochemical examination and analysis of different wound healing mediators via quantitative polymerase chain reaction (qPCR).

Results

Subcutaneous injection of BM-MSCs resulted in the decrease of the wound contraction rate; the wound having a pinpoint appearance and regular arrangement of the epidermal layer with thin stratum corneum; decrease in the area percentages of ADAMs10 expression; significant downregulation of transforming growth factor-β (TGF-β), interleukin-6 (IL-6), tumor necrotic factor-α (TNF-α), metalloproteinase-9 (MMP-9), and microRNA-21; and marked upregulation of heat shock protein-90α (HSP-90α) especially in late stages.

Conclusion

BM-MSCs exhibited a powerful healing property through regulating the mediators of wound healing and restoring the normal skin structures, reducing the scar formation and the wound size.

Will mesenchymal stem cells be future directions for treating radiation-induced skin injury?

Radiation-induced skin injury (RISI) is one of the common serious side effects of radiotherapy (RT) for patients with malignant tumors. Mesenchymal stem cells (MSCs) are applied to RISI repair in some clinical cases series except some traditional options. Though direct replacement of damaged cells may be achieved through differentiation capacity of MSCs, more recent data indicate that various cytokines and chemokines secreted by MSCs are involved in synergetic therapy of RISI by anti-inflammatory, immunomodulation, antioxidant, revascularization, and anti-apoptotic activity. In this paper, we not only discussed different sources of MSCs on the treatment of RISI both in preclinical studies and clinical trials, but also summarized the applications and mechanisms of MSCs in other related regenerative fields.

Biological characteristics of stem cells derived from burned skin-a comparative study with umbilical cord stem cells

INTRODUCTION

Burned human skin, which is routinely excised and discarded, contains viable mesenchymal stromal/stem cells (burn-derived mesenchymal stromal/stem cells; BD-MSCs). These cells show promising potential to enable and aid wound regeneration. However, little is known about their cell characteristics and biological function.

OBJECTIVES

This study had two aims: first, to assess critical and cellular characteristics of BD-MSCs and, second, to compare those results with multipotent well-characterized MSCs from Wharton's jelly of human umbilical cords (umbilical cord mesenchymal stromal/stem cells, UC-MSCs).

METHODS

BD- and UC-MSCs were compared using immunophenotyping, multi-lineage differentiation, seahorse analysis for glycolytic and mitochondrial function, immune surface markers, and cell secretion profile assays.

RESULTS

When compared to UC-MSCs, BD-MSCs demonstrated a lower mesenchymal differentiation capacity and altered inflammatory cytokine secretomes at baseline and after stimulation with lipopolysaccharides. No significant differences were found in population doubling time, colony formation, cell proliferation cell cycle, production of reactive oxygen species, glycolytic and mitochondrial function, and in the expression of major histocompatibility complex I and II and toll-like receptor (TLR).

IMPORTANCE, TRANSLATION

This study reveals valuable insights about MSCs obtained from burned skin and show comparable cellular characteristics with UC-MSCs, highlighting their potentials in cell therapy and skin regeneration.

Chronic senescent human mesenchymal stem cells as possible contributor to the wound healing disorder after exposure to the alkylating agent sulfur mustard

Wound healing is a complex process, and disturbance of even a single mechanism can result in chronic ulcers developing after exposure to the alkylating agent sulfur mustard (SM). A possible contributor may be SM-induced chronic senescent mesenchymal stem cells (MSCs), unable to fulfil their regenerative role, by persisting over long time periods and creating a proinflammatory microenvironment. Here we show that senescence induction in human bone marrow derived MSCs was time- and concentration-dependent, and chronic senescence could be verified 3 weeks after exposure to between 10 and 40 µM SM. Morphological changes, reduced clonogenic and migration potential, longer scratch closure times, differences in senescence, motility and DNA damage response associated genes as well as increased levels of proinflammatory cytokines were revealed. Selective removal of these cells by senolytic drugs, in which ABT-263 showed initial potential in vitro, opens the possibility for an innovative treatment strategy for chronic wounds, but also tumors and age-related diseases.

Stem Cells: A Golden Therapy for Diabetic Wounds

Diabetes mellitus is the 7th leading cause of death worldwide. Diabetes can affect the organ systems and lead to serious complications, majorly categorized as macrovascular complications, microvascular complications, and diabetic wounds. Foot ulcer develops in 15-25% diabetic patients. In diabetic wound, there is an impairment in growth factor, neuropeptide, matrix metalloproteinases, angiogenesis, and immune system. Many approaches are being experimented to manage this major complication of diabetic foot, but unfortunately with lower success rate. Stem cell is an upcoming field which is being explored in the world of diabetes. Hence, this review is designed to understand the basic pathogenesis and complications of types of diabetes and the role of stem cells in a diabetic wound and the benefits related to it.

Role of marijuana components on the regenerative ability of stem cells

Stem cell therapy promotes tissue regeneration and wound healing. Efforts have been made to prime stem cells to enhance their regenerative abilities. Certain marijuana components, namely the non-psychoactive cannabidiol (CBD) and psychoactive tetrahydrocannabinol (THC), are defined as immunomodulators.⁹ We test whether two sources of stem cells, primed with CBD or THC, would demonstrate improved regenerative abilities. Human adipose-derived stem cells (ASCs) and bone marrow-derived stem cells (BMDSCs), not obtained from the same individual, were treated with low (300 nM) or high (3 μM) concentration CBD. Porcine ASCs and BMDSCs were isolated from a single pig, and treated with either low or high concentrations of CBD or THC. Transwell migration and MTT proliferation assays were performed on the human ASCs and BMDSCs. Also, transwell migration assay was performed on the porcine ASCs and BMDSCs. Finally, a wound healing scratch assay in porcine primary fibroblasts (PFs) was performed, co-cultured with the cannabinoid-treated ASCs. CBD priming at low concentration induces migration by 180% (P < .01) in porcine ASCs, and by only 93% (P < .02) in porcine BMDSCs. In porcine stem cells, THC priming at low concentration induces migration by 91.6% (P < .01) in ASCs but by only 44.3% (P < .03) in BMDSCs. Compared to PFs co-cultured with untreated ASCs, PFs co-cultured with low CBD-primed ASCs had 75% faster wound closure at 18 hours (P < .01). CBD and THC priming of ASCs and BMDSCs, particularly at lower doses, enhances a number of regenerative parameters, suggesting that these major marijuana components may improve stem cell-based therapies. SIGNIFICANCE OF THE STUDY: Our study demonstrates that cannabinoids can enhance the regenerative capacity of two major sources of stem cells, adipose- and bone marrow-derived, from human and porcine donors. Stem cell isolation and expansion is invasive, costly and time consuming. Stem cells with improved regenerative properties may be effective in the treatment of acute or chronic wounds. This is the first study to compare the priming potential of two sources of stem cells from the same animal, with the same genetic and epigenetic profile, as well as the first to prime with THC.

Platelet microparticles load a repertory of miRNAs programmed to drive osteogenic phenotype

Autologous platelet-rich plasma accelerates bone healing by releasing biomolecules during their degranulation process, which are transported by vesicle-like structures called platelet microparticles (PMPs). However, the underlying mechanisms regulating the osteogenic differentiation by PMP-released miRs remain poorly understood and this prompted us to better address this issue. Thus, miRNAseq expression profiles (E-GEOD-76789) were downloaded from ArrayExpress database. GEO2R was performed to evaluate the differential expression, and mirnatap R package was used to find targets for differentially expressed miRNAs. An extend protein-protein (ePPI) network for osteogenic marker proteins was generated using String, and DAVID tools were used to perform gene ontology and KEGG pathway analysis from ePPI and miRNAs targets. Our data show that ePPI network was composed by 232 nodes and 2,175 edges, with a clustering coefficient of 0.546. MCODE was able to identify seven clusters contained in the ePPI network, and the two that presented a score above 10 were used in further analysis. Conversely, 15,944 different targets were found as down-expressed while 5,715 different targets were up-expressed. Among the downregulated 75 miRNAs, 70 have predicted targets present in the ePPI network, while the 21 upregulated miRNAs have 19 predicted targets in the ePPI network. Our study provides a registry of miRNAs that play a central role in regulating osteogenic phenotype, which might have potential therapeutic applications in bone regeneration and bone tissue engineering.

A Multifunctional Role of Leucine-Rich α-2-Glycoprotein 1 in Cutaneous Wound Healing Under Normal and Diabetic Conditions

Delayed wound healing is commonly associated with diabetes. It may lead to amputation and death if not treated in a timely fashion. Limited treatments are available partially due to the poor understanding of the complex disease pathophysiology. Here, we investigated the role of leucine-rich α-2-glycoprotein 1 (LRG1) in normal and diabetic wound healing. First, our data showed that LRG1 was significantly increased at the inflammation stage of murine wound healing, and bone marrow-derived cells served as a major source of LRG1. LRG1 deletion causes impaired immune cell infiltration, reepithelialization, and angiogenesis. As a consequence, there is a significant delay in wound closure. On the other hand, LRG1 was markedly induced in diabetic wounds in both humans and mice. LRG1-deficient mice were resistant to diabetes-induced delay in wound repair. We further demonstrated that this could be explained by the mitigation of increased neutrophil extracellular traps (NETs) in diabetic wounds. Mechanistically, LRG1 mediates NETosis in an Akt-dependent manner through TGFβ type I receptor kinase ALK5. Taken together, our studies demonstrated that LRG1 derived from bone marrow cells is required for normal wound healing, revealing a physiological role for this glycoprotein, but that excess LRG1 expression in diabetes is pathogenic and contributes to chronic wound formation.

Combined Transplantation of Mesenchymal Stem Cells and Endothelial Colony-Forming Cells Accelerates Refractory Diabetic Foot Ulcer Healing

Background

This study is aimed at investigating the effect of combined transplantation of umbilical cord mesenchymal stem cells (UCMSCs) and umbilical cord blood-derived endothelial colony-forming cells (ECFCs) on diabetic foot ulcer healing and at providing a novel therapy for chronic diabetic foot ulcer.

Methods

We reported the treatment of refractory diabetic foot ulcers in twelve patients. Among them, five patients had two or more wounds; thus, one wound in the same patient was treated with cell injection, and other wounds were regarded as self-controls. The remaining seven patients had only one wound; therefore, the difference between the area of wound before and after treatment was estimated. The UCMSCs and ECFCs were injected into the wound along with topically applied hyaluronic acid (HA).

Results

In this report, we compared the healing rate of multiple separate wounds in the same foot of the same patient: one treated with cell injection combined with topically applied HA-based hydrogel and was later covered by the hydrocolloid dressings, while the self-control wounds were only treated with conventional therapy and covered by the hydrocolloid dressings. The wound underwent cell injection showed accelerated healing in comparison to control wound within the first week after treatment. In other diabetic patients with only one refractory wound, the healing rate after cell transplantation was significantly faster than that before injection. Two large wounds healed without needing skin grafts after combination therapy of cell injection and HA. After four weeks of combination treatment, wound closure was reached in six patients, and the wounds of the other six patients were significantly reduced in size.

Conclusions

Our study suggests that the combination of UCMSCs, ECFCs, and HA can safely synergize the accelerated healing of refractory diabetic foot ulcers.

[Biotherapies for erectile dysfunction and Peyronie's disease: Where are we now?]

INTRODUCTION

Clinical trials of cell therapy for erectile dysfunction (ED) and Peyronie's disease (PD) were recently conducted after preclinical studies.

AIMS

The aims of this study are to give an update on biotherapy for ED and PD and to describe the regulatory framework for these therapies.

MATERIALS AND METHODS

A literature review was performed through PubMed and Clinical.trials.gov addressing cell therapy for ED and PD and using following keywords "erectile dysfunction", "Peyronie's disease", "stem cell", and "platelet-rich plasma".

RESULTS

Preclinical studies in rodent models have shown the potential benefit of cell therapy for ED after radical prostatectomy or caused by metabolic diseases, and PD. The tissues used to obtain the therapeutic product were bone marrow, adipose tissue and blood (PRP, platelet-rich plasma). Mechanism of action was shown to be temporary and mainly paracrine. Four clinical trials were published concerning ED after radical prostatectomy and in diabetic patients and one for PD. Eleven clinical trials including three randomized trials are currently going on. Preclinical and preliminary clinical results suggested the possibility to improve spontaneous erectile function and response to pharmaceutical treatment in initially non-responder patients. This effect is mediated by an improvement of penile vascularization. A reduction of penile curvature without side effect was noted after injections into the plaque of PD patients. Most of these therapeutic strategies using autologous cells were considered as "Advanced Therapy Medicinal Products" with strict regulatory frameworks imposing heavy constraints, in particular in case of "substantial" modification of the cells. The regulatory framework remains unclear and more permissive for PRP and cell therapy processes with extemporaneous preparation/injection and no "substantial" modifications.

CONCLUSIONS

First results on cell therapy for ED and PD are promising. The regulatory framework can significantly change according to cell preparations and origins leading to various constraints. This regulatory framework is crucial to consider for the choice of the procedure.

Cell-free fat extract accelerates diabetic wound healing in db/db mice

Cell-free fat extract (CEFFE), the liquid fraction derived from fat tissues, is enriched with a variety of growth factors and possesses pro-angiogenic, anti-apoptotic, and anti-oxidative properties. The aim of this study was to determine if CEFFE could accelerate chronic wound healing in mice with diabetes and investigate its underlying mechanisms. A model of circular full-thickness wound (6 mm diameter) was produced in the central dorsal region of spontaneous type 2 diabetes mellitus db/db mice. The mice were divided to three groups depending on dosage of CEFFE administered for the study; high dose CEFFE group (CEFFE^high; administered 2.5 ml/kg/day via subcutaneous injection for six days), low dose CEFFE group (CEFFE^low; administered 2.5 ml/kg/day via subcutaneous injection for three days), and a control group receiving phosphate buffer solution. Wound closure was evaluated on day 3, 7, 10, and 14 post-operation. Histological analyses, including hematoxylin-eosin staining and Masson's trichrome staining and immunohistological staining of anti-CD31 and anti-CD68, were also performed. Moreover, the effects of CEFFE on proliferation, migration, and tube formation of human immortal keratinocyte cells (HaCaT) and human vascular endothelial cells (HUVEC) were tested in vitro. The results showed that the local injection of CEFFE significantly accelerated wound healing in mice with diabetes. CEFFE improved re-epithelization and collagen secretion, promoted angiogenesis, and inhibited inflammatory macrophage infiltration in vivo. CEFFE also promoted HaCaT proliferation and migration and enhanced tubular formation in cultured HUVEC. It was concluded that CEFFE accelerates wound healing through pro-angiogenic and anti-inflammatory activities.

Evaluation of epithelial progenitor cells and growth factors in a preclinical model of wound healing induced by mesenchymal stromal cells

Background: Skin wounds continue to be a global health problem. Several cellular therapy protocols have been used to improve and accelerate skin wound healing. Here, we evaluated the effect of transplantation of mesenchymal stromal cells (MSC) on the wound re-epithelialization process and its possible relationship with the presence of epithelial progenitor cells (EPC) and the expression of growth factors. Methods: An experimental wound model was developed in C57BL/6 mice. Human MSCs seeded on collagen membranes (CM) were implanted on wounds. As controls, animals with wounds without treatment or treated with CM were established. Histological and immunohistochemical (IH) studies were performed at day 3 post-treatment to detect early skin wound changes associated with the presence of EPC expressing Lgr6 and CD34 markers and the expression of keratinocyte growth factor (KGF) and basic fibroblast growth factor (bFGF). Results: MSC transplantation enhanced skin wound re-epithelialization, as compared with controls. It was associated with an increase in Lgr6⁺ and CD34⁺ cells and the expression of KGF and bFGF in the wound bed. Conclusion: Our results show that cutaneous wound healing induced by MSC is associated with an increase in EPC and growth factors. These preclinical results support the possible clinical use of MSC to treat cutaneous wounds.

Three dimensional microcarrier system in mesenchymal stem cell culture: a systematic review

Stem cell-based regenerative medicine is a promising approach for tissue reconstruction. However, a large number of cells are needed in a typical clinical study, where conventional monolayer cultures might pose a limitation for scale-up. The purpose of this review was to systematically assess the application of microcarriers in Mesenchymal Stem Cell cultures. A comprehensive search was conducted in Medline via Ebscohost, Pubmed, and Scopus, and relevant studies published between 2015 and 2019 were selected. The literature search identified 53 related studies, but only 14 articles met the inclusion criteria. These include 7 utilised commercially available microcarriers, while the rest were formulated based on different surface characteristics, all of which are discussed in this review. Current applications of microcarriers were focused on MSC expansion and induction of MSCs into different lineages. These studies demonstrated that MSCs could proliferate in a microcarrier culture system in-fold compared to monolayer cultures, and the culture system could simulate a three-dimensional environment which induces cell differentiation. However, detailed studies are still required before this system were to be adapted into the scale of GMP manufacturing.

Deletion of Peroxiredoxin II Inhibits the Growth of Mouse Primary Mesenchymal Stem Cells Through Induction of the G0/G1 Cell-cycle Arrest and Activation of AKT/GSK3β/β-Catenin Signaling

BACKGROUND/AIM

Dermal mesenchymal stem cells (DMSCs) are pluripotent stem cells found in the skin which maintain the thickness of the dermal layer and participate in skin wound healing.

MATERIALS AND METHODS

The MTT assay was performed to detect cell proliferation and cell-cycle progression and cell-surface markers were assessed by flow cytometry. The levels of proteins in related signaling pathways were detected by western blotting assay and the translocation of β-catenin into the nucleus were detected by immunofluorescence. Red oil O staining was performed to examine the differentiational ability of DMSCs.

RESULTS

Knockout of PRDX2 inhibited DMSC cell growth, and cell-cycle arrest at G₀/G₁ phase; p16, p21 and cyclin D1 expression levels in Prdx2 knockout DMSCs were significantly increased. Furthermore, AKT phosphorylation were significantly increased in Prdx2 knockout DMSCs, GSK3β activity were inhibited, result in β-Catenin accumulated in the nucleus.

CONCLUSION

In conclusion, these results demonstrated that PRDX2 plays a pivotal role in regulating the proliferation of DMSCs, and this is closely related to the AKT/glycogen synthase kinase 3 beta/β-catenin signaling pathway.

Identifying the Therapeutic Significance of Mesenchymal Stem Cells

The pleiotropic behavior of mesenchymal stem cells (MSCs) has gained global attention due to their immense potential for immunosuppression and their therapeutic role in immune disorders. MSCs migrate towards inflamed microenvironments, produce anti-inflammatory cytokines and conceal themselves from the innate immune system. These signatures are the reason for the uprising in the sciences of cellular therapy in the last decades. Irrespective of their therapeutic role in immune disorders, some factors limit beneficial effects such as inconsistency of cell characteristics, erratic protocols, deviating dosages, and diverse transfusion patterns. Conclusive protocols for cell culture, differentiation, expansion, and cryopreservation of MSCs are of the utmost importance for a better understanding of MSCs in therapeutic applications. In this review, we address the immunomodulatory properties and immunosuppressive actions of MSCs. Also, we sum up the results of the enhancement, utilization, and therapeutic responses of MSCs in treating inflammatory diseases, metabolic disorders and diabetes.

Locally Delivered Umbilical Cord Mesenchymal Stromal Cells Reduce Chronic Inflammation in Long-Term Nonhealing Wounds: A Randomized Study

Inflammation is part of a complex biological response to injury that mediates a rapid mobilization of cells and triggers the restoration of tissue homeostasis. The systemic diseases of the connective tissues, repetitive strain injuries, neuropathy, and vascular impairment lead to the development of a chronic inflammatory state. In such cases, a forced intervention is required to trigger tissue regeneration. Mesenchymal stromal cells (MSCs) have been considered a perspective tool for regenerative medicine because of their ability to change the expression and secretory profile under the influence of signals from the microenvironment to perform a regulatory function at the site of tissue damage. In this study, MSCs were isolated from the human umbilical cord (UCMSCs). The ability of UCMSCs to regulate chronic inflammation was investigated in a randomized placebo-controlled pilot study to assess the efficacy and safety of UCMSC therapy in patients with nonhealing wounds. A total of 108 patients with chronic wounds of different etiologies were randomly divided into two groups according to the criteria of inclusion and exclusion. The group (n = 59) that was treated with a single local subcutaneous infusion of UCMSCs around the wound periphery showed a pronounced growth of granulation tissue, improved blood microcirculation, and reduction in wound size compared to the placebo group (n = 49). No prominent adverse events were detected in patients from the UCMSC group during the 1-year follow-up period. This research has demonstrated that locally delivered allogeneic UCMSCs can contribute to chronic wound repair and provide an additional support toward new therapeutic strategies. Registration certificate №FS2006/341 was issued by the Federal Service for Surveillance in Healthcare.

Chronic Wounds: Innovations in Diagnostics and Therapeutics

BACKGROUND

A major global health issue is the existence of chronic wounds. Appropriate diagnosis and treatment is essential to promote wound healing and prevent further complications. Traditional methods for treatment and diagnosis of chronic wounds have shown to be of limited effectiveness. Therefore, there is a need for the development of diagnostic and therapeutic innovations in chronic wound care.

OBJECTIVE

This mini-review aims to provide insight in the current knowledge of the wound healing process and the deficiencies encountered in chronic wounds, which provides a basis for the development of innovations in chronic wound care. Furthermore, promising diagnostic and therapeutic innovations will be highlighted.

METHODS

Literature was searched for recent articles (=<10 years) describing the current knowledge about the wound healing process and chronic wounds. The most promising diagnostic and therapeutic innovations were gathered from articles published in the past 5 years.

RESULTS/CONCLUSION

Wound healing is a well-organized process consisting of four phases: coagulation, inflammation, proliferation and wound remodelling. Chronic wounds often stagnate in the inflammatory phase and/or experience an impaired proliferative phase. This mini-review has demonstrated that increased knowledge about the processes involved in wound healing has paved the way for the development of new diagnostic tools and treatments for chronic wounds. Increased knowledge about bacterial invasion and infection in has encouraged researchers to develop diagnostic tools to help clinicians detect these phenomena appropriately and in time. Other researchers have shown that they are able to design/extract biochemical compounds that intervene in the disrupted healing processes in chronic wounds.

Role of Mesenchymal Stem Cell-Derived Extracellular Vesicles in Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) is a process that takes place during embryonic development, wound healing, and under some pathological processes, including fibrosis and tumor progression. The molecular changes occurring within epithelial cells during transformation to a mesenchymal phenotype have been well studied. However, to date, the mechanism of EMT induction remains to be fully elucidated. Recent findings in the field of intercellular communication have shed new light on this process and indicate the need for further studies into this important mechanism. New evidence supports the hypothesis that intercellular communication between mesenchymal stroma/stem cells (MSCs) and resident epithelial cells plays an important role in EMT induction. Besides direct interactions between cells, indirect paracrine interactions by soluble factors and extracellular vesicles also occur. Extracellular vesicles (EVs) are important mediators of intercellular communication, through the transfer of biologically active molecules, genetic material (mRNA, microRNA, siRNA, DNA), and EMT inducers to the target cells, which are capable of reprogramming recipient cells. In this review, we discuss the role of intercellular communication by EVs to induce EMT and the acquisition of stemness properties by normal and tumor epithelial cells.

Human amniotic mesenchymal stem cells and their paracrine factors promote wound healing by inhibiting heat stress-induced skin cell apoptosis and enhancing their proliferation through activating PI3K/AKT signaling pathway

Background

Increasing evidence has shown that mesenchymal stem cells (MSCs) yield a favorable therapeutic benefit for thermal burn skin wounds. Human amniotic MSCs (hAMSCs) derived from amniotic membrane have multilineage differentiation, immunosuppressive, and anti-inflammatory potential which makes them suitable for treating skin wounds. However, the exact effects of hAMSCs on the healing of thermal burn skin wounds and their potential mechanisms are not explored.

Methods

hAMSCs were isolated from amniotic membrane and characterized by RT-PCR, flow cytometry, immunofluorescence, and tumorigenicity test. We assessed the effects of hAMSCs and hAMSC conditional medium (CM) on wound healing in a deep second-degree burn injury model of mice. We then investigated the biological effects of hAMSCs and hAMSC-CM on the apoptosis and proliferation of heat stress-injured human keratinocytes HaCAT and dermal fibroblasts (DFL) both in vivo and in vitro. Next, we explored the underlying mechanisms by assessing PI3K/AKT and GSK3β/β-catenin signaling pathways in heat injured HaCAT and DFL cells after hAMSCs and hAMSC-CM treatments using PI3K inhibitor LY294002 and β-catenin inhibitor ICG001. Antibody array assay was used to identify the cytokines secreted by hAMSCs that may activate PI3K/AKT signaling pathway.

Results

Our results showed that hAMSCs expressed various markers of embryonic stem cells and mesenchymal stem cells and have low immunogenicity and no tumorigenicity. hAMSC and hAMSC-CM transplantation significantly promoted thermal burn wound healing by accelerating re-epithelialization with increased expression of CK19 and PCNA in vivo. hAMSCs and hAMSC-CM markedly inhibited heat stress-induced apoptosis in HaCAT and DFL cells in vitro through activation of PI3K/AKT signaling and promoted their proliferation by activating GSK3β/β-catenin signaling. Furthermore, we demonstrated that hAMSC-mediated activation of GSK3β/β-catenin signaling was dependent on PI3K/AKT signaling pathway. Antibody array assay showed that a panel of cytokines including PAI-1, C-GSF, periostin, and TIMP-1 delivered from hAMSCs may contribute to the improvement of the wound healing through activating PI3K/AKT signaling pathway.

Conclusion

Our results demonstrated that hAMSCs and hAMSC-CM efficiently cure heat stress-induced skin injury by inhibiting apoptosis of skin cells and promoting their proliferation through activating PI3K/AKT signaling pathway, suggesting that hAMSCs and hAMSC-CM may provide an alternative therapeutic approach for the treatment of skin injury.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1366-y) contains supplementary material, which is available to authorized users.

Acellular and cellular approaches to improve diabetic wound healing

Chronic diabetic wounds represent a huge socioeconomic burden for both affected individuals and the entire healthcare system. Although the number of available treatment options as well as our understanding of wound healing mechanisms associated with diabetes has vastly improved over the past decades, there still remains a great need for additional therapeutic options. Tissue engineering and regenerative medicine approaches provide great advantages over conventional treatment options, which are mainly aimed at wound closure rather than addressing the underlying pathophysiology of diabetic wounds. Recent advances in biomaterials and stem cell research presented in this review provide novel ways to tackle different molecular and cellular culprits responsible for chronic and nonhealing wounds by delivering therapeutic agents in direct or indirect ways. Careful integration of different approaches presented in the current article could lead to the development of new therapeutic platforms that can address multiple pathophysiologic abnormalities and facilitate wound healing in patients with diabetes.

Current and Future Perspectives on Skin Tissue Engineering: Key Features of Biomedical Research, Translational Assessment, and Clinical Application

The skin is responsible for several important physiological functions and has enormous clinical significance in wound healing. Tissue engineered substitutes may be used in patients suffering from skin injuries to support regeneration of the epidermis, dermis, or both. Skin substitutes are also gaining traction in the cosmetics and pharmaceutical industries as alternatives to animal models for product testing. Recent biomedical advances, ranging from cellular-level therapies such as mesenchymal stem cell or growth factor delivery, to large-scale biofabrication techniques including 3D printing, have enabled the implementation of unique strategies and novel biomaterials to recapitulate the biological, architectural, and functional complexity of native skin. This progress report highlights some of the latest approaches to skin regeneration and biofabrication using tissue engineering techniques. Current challenges in fabricating multilayered skin are addressed, and perspectives on efforts and strategies to meet those limitations are provided. Commercially available skin substitute technologies are also examined, and strategies to recapitulate native physiology, the role of regulatory agencies in supporting translation, as well as current clinical needs, are reviewed. By considering each of these perspectives while moving from bench to bedside, tissue engineering may be leveraged to create improved skin substitutes for both in vitro testing and clinical applications.

Mesenchymal stem cell basic research and applications in dog medicine

The stem cells, owing to their special characteristics like self-renewal, multiplication, homing, immunomodulation, anti-inflammatory, and dedifferentiation are considered to carry an "all-in-one-solution" for diverse clinical problems. However, the limited understanding of cellular physiology currently limits their definitive therapeutic use. Among various stem cell types, currently mesenchymal stem cells are extensively studied for dog clinical applications owing to their readily available sources, easy harvesting, and ability to differentiate both into mesodermal, as well as extramesodermal tissues. The isolated, culture expanded, and characterized cells have been applied both at preclinical as well as clinical settings in dogs with variable but mostly positive results. The results, though positive, are currently inconclusive and demands further intensive research on the properties and their dependence on the applications. Further, numerous clinical conditions of dog resemble to that of human counterparts and thus, if proved rewarding in the former may act as basis of therapy for the latter. The current review throws some light on dog mesenchymal stem cell properties and their potential therapeutic applications.

Autologous bone marrow-derived cells for venous leg ulcers treatment: a pilot study

BACKGROUND

Chronic venous leg ulcers (VLUs) are a common problem in clinical practice and available treatments are not satisfactory. The use of adjuvant therapies in combination with lower limb compression may lead to improved healing rates. Chronic wounds are candidates for new strategies in the emergent field of regenerative medicine. Bone marrow-derived cells (BMDCs) contain cells and secrete cytokines known to participate in wound healing. Thus, BMDC therapy seems a logical strategy for the treatment of chronic wounds. Our objective was to evaluate feasibility, safety and initial clinical outcome of autologous BMDC therapy associated with standard treatment in patients with VLUs.

METHODS

We conducted an open-label, single-arm, prospective pilot clinical trial in four patients with six chronic VLUs. The study protocol was approved by the institutional and national review boards and ethics committees. Bone marrow was harvest, processed and then administered by multiple injections into the ulcers. All patients received standard treatment and non-healing characteristics of the VLUs were confirmed at study entry.

RESULTS

Ulcer size and wound pain evaluated 12 months after BMDC treatment were significantly reduced (P < 0.05). BMDC treatment was safe and well tolerated in long-term follow-up.

DISCUSSION

Despite the low number of patients studied, our results showed that autologous BMDC treatment could be a useful, feasible and safe procedure to enhance ulcer healing. However, randomized controlled trials with more patients are needed to address this question and translate this approach into clinical practice.

Approaches to cutaneous wound healing: basics and future directions

The skin provides essential functions, such as thermoregulation, hydration, excretion and synthesis of vitamin D. Major disruptions of the skin cause impairment of critical functions, resulting in high morbidity and death, or leave one with life-changing cosmetic damage. Due to the complexity of the skin, diverse approaches are needed, including both traditional and advanced, to improve cutaneous wound healing. Cutaneous wounds undergo four phases of healing. Traditional management, including skin grafts and wound dressings, is still commonly used in current practice but in combination with newer technology, such as using engineered skin substitutes in skin grafts or combining traditional cotton gauze with anti-bacterial nanoparticles. Various upcoming methods, such as vacuum-assisted wound closure, engineered skin substitutes, stem cell therapy, growth factors and cytokine therapy, have emerged in recent years and are being used to assist wound healing, or even to replace traditional methods. However, many of these methods still lack assessment by large-scale studies and/or extensive application. Conceptual changes, for example, precision medicine and the rapid advancement of science and technology, such as RNA interference and 3D printing, offer tremendous potential. In this review, we focus on the basics of wound treatment and summarize recent developments involving both traditional and hi-tech therapeutic methods that lead to both rapid healing and better cosmetic results. Future studies should explore a more cost-effective, convenient and efficient approach to cutaneous wound healing. Graphical abstract Combination of various materials to create advanced wound dressings.

Emerging Development of Microfluidics-Based Approaches to Improve Studies of Muscle Cell Migration

IMPACT STATEMENT

The essential interactions between and among cells in the three types of muscle tissue in development, wound healing, and regeneration of tissues, are underpinned by the ability of cardiac, smooth, and skeletal muscle cells to migrate in maintaining functional capacity after pathologies such as myocardial infarction, tissue grafting, and traumatic and postsurgical injury. Microfluidics-based devices now offer significant enhancement over conventional approaches to studying cell chemotaxis and haptotaxis that are inherent in migration. Advances in experimental approaches to muscle cell movement and tissue formation will contribute to innovations in tissue engineering for patching wound repair and muscle tissue replacement.

Protein-Engineered Large Area Adipose-derived Stem Cell Sheets for Wound Healing

Human adipose-derived stem cells (hADSCs) formed robust cell sheets by engineering the cells with soluble cell adhesive molecules (CAMs), which enabled unique approaches to harvest large area hADSC sheets. As a soluble CAM, fibronectin (FN) (100 pg/ml) enhanced the cell proliferation rate and control both cell-to-cell and cell-to-substrate interactions. Through this engineering of FN, a transferrable hADSC sheet was obtained as a free-stranding sheet (122.6 mm²) by a photothermal method. During the harvesting of hADSC sheets by the photothermal method, a collagen layer in-between cells and conductive polymer film (CP) was dissociated, to protect cells from direct exposure to a near infrared (NIR) source. The hADSC sheets were applied to chronic wound of genetically diabetic db/db mice in vivo, to accelerate 30% faster wound closure with a high closure effect (ε_wc) than that of control groups. These results indicated that the engineering of CAM and collagens allow hADSC sheet harvesting, which could be extended to engineer various stem cell sheets for efficient therapies.

Three-Dimensional (3D) Printed Microneedles for Microencapsulated Cell Extrusion

Cell-hydrogel based therapies offer great promise for wound healing. The specific aim of this study was to assess the viability of human hepatocellular carcinoma (HepG2) cells immobilized in atomized alginate capsules (3.5% (w/v) alginate, d = 225 µm ± 24.5 µm) post-extrusion through a three-dimensional (3D) printed methacrylate-based custom hollow microneedle assembly (circular array of 13 conical frusta) fabricated using stereolithography. With a jetting reliability of 80%, the solvent-sterilized device with a root mean square roughness of 158 nm at the extrusion nozzle tip (d = 325 μm) was operated at a flowrate of 12 mL/min. There was no significant difference between the viability of the sheared and control samples for extrusion times of 2 h (p = 0.14, α = 0.05) and 24 h (p = 0.5, α = 0.05) post-atomization. Factoring the increase in extrusion yield from 21.2% to 56.4% attributed to hydrogel bioerosion quantifiable by a loss in resilience from 5470 (J/m³) to 3250 (J/m³), there was no significant difference in percentage relative payload (p = 0.2628, α = 0.05) when extrusion occurred 24 h (12.2 ± 4.9%) when compared to 2 h (9.9 ± 2.8%) post-atomization. Results from this paper highlight the feasibility of encapsulated cell extrusion, specifically protection from shear, through a hollow microneedle assembly reported for the first time in literature.

Extracellular vesicles as modulators of wound healing

Impaired healing of cutaneous wounds and ulcers continues to have a major impact on the quality of life of millions of people. In recent years, the capacity for stem and progenitor cells to promote wound repair has been investigated with evidence that secreted factors are responsible for the observed therapeutic benefits. This review addresses current evidence in support of stem/progenitor cell-derived extracellular vesicles (EVs) as a regenerative therapy for acceleration of wound healing. Encouraging results for local or systemic administration of EVs have been reported in a range of clinically-relevant animal models of cutaneous wounds. Furthermore, a number of plausible mechanisms involving EV-mediated transfer of proteins and RNAs that trigger pro-repair pathways in target cells have been demonstrated experimentally. However, for successful clinical translation in the coming years, further emphasis on standardized experimental protocols, detailed methodological reporting and clear definition of EV-based therapeutic products will be required.

Immunology Guides Skeletal Muscle Regeneration

Soft tissue trauma of skeletal muscle is one of the most common side effects in surgery. Muscle injuries are not only caused by accident-related injuries but can also be of an iatrogenic nature as they occur during surgical interventions when the anatomical region of interest is exposed. If the extent of trauma surpasses the intrinsic regenerative capacities, signs of fatty degeneration and formation of fibrotic scar tissue can occur, and, consequentially, muscle function deteriorates or is diminished. Despite research efforts to investigate the physiological healing cascade following trauma, our understanding of the early onset of healing and how it potentially determines success or failure is still only fragmentary. This review focuses on the initial physiological pathways following skeletal muscle trauma in comparison to bone and tendon trauma and what conclusions can be drawn from new scientific insights for the development of novel therapeutic strategies. Strategies to support regeneration of muscle tissue after injury are scarce, even though muscle trauma has a high incidence. Based on tissue specific differences, possible clinical treatment options such as local immune-modulatory and cell therapeutic approaches are suggested that aim to support the endogenous regenerative potential of injured muscle tissues.

Stem Cell Therapy in Wound Healing

Wound healing is a complex restorative process of the altered cutaneous tissue, which is impaired by numerous local and systemic factors, leading to chronic non-healing lesions with few efficient therapeutic options. Stem cells possess the capacity to differentiate into various types of cell lines. Furthermore, stem cells are able to secrete cytokines and growth factors, modulating inflammation and ultimately leading to angiogenesis, fibrogenesis, and epithelization. Because of their paracrine activity, these cells are able to attract other cell types to the base of the wound, improving the formation of new skin layers. Mesenchymal stem cells derived from the adipose tissue, bone marrow, and placenta, offer numerous ways of implementation. The process of harvesting, growing, and administrating stem cells depends on the site and type of the cells, but recent trial results showed improvement of wound healing independent of the administration site. Bioengineered skin substitutes are validated for treatment of chronic wounds with direct application on the skin surface. These offer physical scaffolding for the migrating cells and promote secretion of growth factors, thus facilitating rapid wound healing. Obtaining further clinical data is essential, but stem cell therapy may become a first-line therapeutic choice for the treatment of non-healing chronic wounds.