Allogeneic mesenchymal stem cells for treatment of severe burn injury

Advancements in cell-based therapies for thermal burn wounds: a comprehensive systematic review of clinical trials outcomes

BACKGROUND

Burn trauma is one of the major causes of morbidity and mortality worldwide. The standard management of burn wounds consists of early debridement, dressing changes, surgical management, and split-thickness skin autografts (STSGs). However, there are limitations for the standard management that inclines us to find alternative treatment approaches, such as innovative cell-based therapies. We aimed to systematically review the different aspects of cell-based treatment approaches for burn wounds in clinical trials.

METHODS

A systematic search through PubMed, Medline, Embase, and Cochrane Library databases was carried out using a combination of keywords, including "Cell transplantation", "Fibroblast", "Keratinocyte", "Melanocyte", or "Stem Cell" with "Burn", "Burn wound", or "Burn injury". Firstly, titles and abstracts of the studies existing in these databases until "February 2024" were screened. Then, the selected studies were read thoroughly, and considering the inclusion and exclusion criteria, final articles were included in this systematic review. Moreover, a manual search was performed through the reference lists of the included studies to minimize the risk of missing reports.

RESULTS

Overall, 30 clinical trials with 970 patients were included in our study. Considering the type of cells, six studies used keratinocytes, nine used fibroblasts, eight used combined keratinocytes and fibroblasts, one study used combined keratinocytes and melanocytes, five used combined keratinocytes and fibroblasts and melanocytes, and one study used mesenchymal stem cells (MSCs). Evaluation of the preparation type in these studies showed that cultured method was used in 25 trials, and non-cultured method in 5 trials. Also, the graft type of 17 trials was allogeneic, and of 13 other trials was autologous.

CONCLUSIONS

Our study showed that employing cell-based therapies for the treatment of burn wounds have significant results in clinical studies and are promising approaches that can be considered as alternative treatments in many cases. However, choosing appropriate cell-based treatment for each burn wound is essential and depends on the situation of each patient.

Alpha terpineol preconditioning enhances regenerative potential of mesenchymal stem cells in full thickness acid burn wounds

Regeneration of full thickness burn wounds is a significant clinical challenge. Direct stem cell transplantation at the wound site has a promising effect on wound regeneration. However, stem cell survival within the harsh wound environment is critically compromised. In this regard, preconditioning of stem cells with cytoprotective compounds can improve the efficiency of transplanted cells. This study evaluated the possible effect of alpha terpineol (αT) preconditioned mesenchymal stem cells (αT-MSCs) in full thickness acid burn wound. An optimized concentration of 10 μM αT was used for MSC preconditioning, followed by scratch assay analysis. A novel rat model of full thickness acid burn wound was developed and characterized via macroscopic and histological examinations. Treatment (normal and αT-MSCs) was given after 48 h of burn wound induction, and the healing pattern was examined till day 40. Skin tissues were harvested at the early (day 10) and late (day 40) wound healing phases and examined by histological grading, neovascularization, and gene expression profiling of healing mediators. In scratch assay, αT-MSCs exhibited enhanced cell migration and wound closure (scratch gap) compared to normal MSCs. In vivo findings revealed enhanced regeneration in the wound treated with αT-MSCs compared to normal MSCs and untreated control. Histology revealed enhanced collagen deposition with regenerated skin layers in normal MSC- and αT-MSC treated groups compared to the untreated control. These findings were correlated with enhanced expression of α-SMA as shown by immunohistochemistry. Additionally, αT-MSC group showed reduced inflammation and oxidative stress, and enhanced regeneration, as witnessed by a decrease in IL-1β, IL-6, TNF-α, and Bax and an increase in BCL-2, PRDX-4, GPX-7, SOD-1, VEGF, EGF, FGF, MMP-9, PDGF, and TGF-β gene expression levels at early and late phases, respectively. Overall findings demonstrated that αT exerts its therapeutic effect by mitigating excessive inflammation and oxidative stress while concurrently enhancing neovascularization. Thus, this study offers new perspectives on managing full thickness acid burn wounds in future clinical settings.

Revolutionizing dermatology: harnessing mesenchymal stem/stromal cells and exosomes in 3D platform for skin regeneration

Contemporary trends reveal an escalating interest in regenerative medicine-based interventions for addressing refractory skin defects. Conventional wound healing treatments, characterized by high costs and limited efficacy, necessitate a more efficient therapeutic paradigm to alleviate the economic and psychological burdens associated with chronic wounds. Mesenchymal stem/stromal cells (MSCs) constitute cell-based therapies, whereas cell-free approaches predominantly involve the utilization of MSC-derived extracellular vesicles or exosomes, both purportedly safe and effective. Exploiting the impact of MSCs by paracrine signaling, exosomes have emerged as a novel avenue capable of positively impacting wound healing and skin regeneration. MSC-exosomes confer several advantages, including the facilitation of angiogenesis, augmentation of cell proliferation, elevation of collagen production, and enhancement of tissue regenerative capacity. Despite these merits, challenges persist in clinical applications due to issues such as poor targeting and facile removal of MSC-derived exosomes from skin wounds. Addressing these concerns, a three-dimensional (3D) platform has been implemented to emend exosomes, allowing for elevated levels, and constructing more stable granules possessing distinct therapeutic capabilities. Incorporating biomaterials to encapsulate MSC-exosomes emerges as a favorable approach, concentrating doses, achieving intended therapeutic effectiveness, and ensuring continual release. While the therapeutic potential of MSC-exosomes in skin repair is broadly recognized, their application with 3D biomaterial scenarios remains underexplored. This review synthesizes the therapeutic purposes of MSCs and exosomes in 3D for the skin restoration, underscoring their promising role in diverse dermatological conditions. Further research may establish MSCs and their exosomes in 3D as a viable therapeutic option for various skin conditions.

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

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

Seconds Timescale Synthesis of Highly Stretchable Antibacterial Hydrogel for Skin Wound Closure and Epidermal Strain Sensor

Effective wound healing is critical for patient care, and the development of novel wound dressing materials that promote healing, prevent infection, and are user-friendly is of great importance, particularly in the context of point-of-care testing (POCT). This study reports the synthesis of a hydrogel material that can be produced in less than 10 s and possesses antibacterial activity against both gram-negative and gram-positive microorganisms, as well as the ability to inhibit the growth of eukaryotic cells, such as yeast. The hydrogel is formed wholly based on covalent-like hydrogen bonding interactions and exhibits excellent mechanical properties, with the ability to stretch up to more than 600% of its initial length. Furthermore, the hydrogel demonstrates ultra-fast self-healing properties, with fractures capable of being repaired within 10 s. This hydrogel can promote skin wound healing, with the added advantage of functioning as a strain sensor that generates an electrical signal in response to physical deformation. The strain sensor composed of a rubber shell realizes fast and responsive strain sensing. The findings suggest that this hydrogel has promising applications in the field of POCT for wound care, providing a new avenue for improved patient outcomes.

Regulation Mechanisms and Maintenance Strategies of Stemness in Mesenchymal Stem Cells

Stemness pertains to the intrinsic ability of mesenchymal stem cells (MSCs) to undergo self-renewal and differentiate into multiple lineages, while simultaneously impeding their differentiation and preserving crucial differentiating genes in a state of quiescence and equilibrium. Owing to their favorable attributes, including uncomplicated isolation protocols, ethical compliance, and ease of procurement, MSCs have become a focal point of inquiry in the domains of regenerative medicine and tissue engineering. As age increases or ex vivo cultivation is prolonged, the functionality of MSCs decreases and their stemness gradually diminishes, thereby limiting their potential therapeutic applications. Despite the existence of several uncertainties surrounding the comprehension of MSC stemness, considerable advancements have been achieved in the clarification of the potential mechanisms that lead to stemness loss, as well as the associated strategies for stemness maintenance. This comprehensive review provides a systematic overview of the factors influencing the preservation of MSC stemness, the molecular mechanisms governing it, the strategies for its maintenance, and the therapeutic potential associated with stemness. Finally, we underscore the obstacles and prospective avenues in present investigations, providing innovative perspectives and opportunities for the preservation and therapeutic utilization of MSC stemness.

The Effect of Mesenchymal Stem Cells on the Wound Infection

Wound infection often requires a long period of care and an onerous treatment process. Also, the rich environment makes the wound an ideal niche for microbial growth. Stable structures, like biofilm, and drug-resistant strains cause a delay in the healing process, which has become one of the important challenges in wound treatment. Many studies have focused on alternative methods to deal the wound infections. One of the novel and highly potential ways is mesenchymal stromal cells (MSCs). MSCs are mesoderm-derived pluripotent adult stem cells with the capacity for self-renewal, multidirectional differentiation, and immunological control. Also, MSCs have anti-inflammatory and antiapoptotic effects. MScs, as pluripotent stromal cells, differentiate into many mature cells. Also, MSCs produce antimicrobial compounds, such as antimicrobial peptides (AMP), as well as secrete immune modulators, which are two basic features considered in wound healing. Despite the advantages, preserving the structure and activity of MSCs is considered one of the most important points in the treatment. MSCs' antimicrobial effects on microorganisms involved in wound infection have been confirmed in various studies. In this review, we aimed to discuss the antimicrobial and therapeutic applications of MSCs in the infected wound healing processes.

Allogeneic Mesenchymal Stem Cells After In Vivo Transplantation: A Review

Autologous mesenchymal stem cells (MSCs) are ideal for tissue regeneration because of their ability to circumvent host rejection, but their procurement and processing present logistical and time-sensitive challenges. Allogeneic MSCs provide an alternative cell-based therapy capable of positively affecting all human organ systems, and can be readily available. Extensive research has been conducted in the treatment of autoimmune, degenerative, and inflammatory diseases with such stem cells, and has demonstrated predominantly safe outcomes with minimal complications. Nevertheless, continued clinical trials are necessary to ascertain optimal harvest and transplant techniques.

Wound healing by transplantation of mesenchymal stromal cells loaded on polyethylene terephthalate scaffold: Implications for skin injury treatment

BACKGROUND

Several clinical studies have shown that cellular therapy based on mesenchymal stromal cells (MSCs) transplantation may accelerate wound healing. One major challenge is the delivery system used for MSCs transplantation. In this work, we evaluated the capacity of a scaffold based on polyethylene terephthalate (PET) to maintain the viability and biological functions of MSCs, in vitro. We examined the capacity of MSCs loaded on PET (MSCs/PET) to induce wound healing in an experimental model of full-thickness wound.

METHODS

Human MSCs were seeded and cultured on PET membranes at 37 °C for 48 h. Adhesion, viability, proliferation, migration, multipotential differentiation and chemokine production were evaluated in cultures of MSCs/PET. The possible therapeutic effect of MSCs/PET on the re-epithelialization of full thickness wounds was examined at day 3 post-wounding in C57BL/6 mice. Histological and immunohistochemical (IH) studies were performed to evaluate wound re-epithelialization and the presence of epithelial progenitor cells (EPC). As controls, wounds without treatment or treated with PET were established.

RESULTS

We observed MSCs adhered to PET membranes and maintained their viability, proliferation and migration. They preserved their multipotential capacity of differentiation and ability of chemokine production. MSCs/PET implants promoted an accelerated wound re-epithelialization, after three days post-wounding. It was associated with the presence of EPC Lgr6⁺ and K6⁺.

DISCUSSION

Our results show that MSCs/PET implants induce a rapid re-epithelialization of deep- and full-thickness wounds. MSCs/PET implants constitute a potential clinical therapy for treating cutaneous wounds.

The Role of Cell-Based Therapies in Acute Burn Wound Skin Repair: A Review

Tissue engineering solutions for skin have been developed over the last few decades with a focus initially on a two-layered structure with epithelial and dermal repair. An essential element of skin restoration is a source of cells capable of differentiating into the appropriate phenotype. The need to repair areas of skin when traditional techniques were not adequate addressed led to cell based therapies being developed initially as a laboratory-based tissue expansion opportunity, both as sheets of cultured epithelial autograft and in composite laboratory-based skin substitutes. The time to availability of the cell-based therapies has been solved in a number of ways, from using allograft cell-based solutions to the use of point of care skin cell harvesting for immediate clinical use. More recently pluripotential cells have been explored providing a readily available source of cells and cells which can express the broad range of phenotypes seen in the mature skin construct. The lessons learnt from the use of cell based techniques has driven the exploration of the use of 3D printing technology, with controlled accurate placement of the cells within a specific printed construct to optimise the phenotypic expression and tissue generation.

Clinical Application of Pre-Expanded Perforator Flaps

Background: Challenging large soft tissue defects are typically treated with microvascular free tissue transfer; however, success has been noted with pre-expanded perforator flaps. Objective: To report outcomes and complications from pre-expanded perforator flaps. Methods: A retrospective chart review of patients undergoing tissue reconstruction with pre-expanded perforator flaps between 2014 and 2020. Data collection included flap type, defect characteristics, and complications. Results: All 29 patients had successful flap reconstruction without major complication. The median area of tissue defect was 17 × 13 cm² (range 7 × 4 to 27 × 24 cm²). Mean tissue expansion period was 15.2 weeks (range 9-26 weeks). The most common flap was the pre-expanded internal mammary artery perforator flaps. Conclusion: The findings of this study suggest that combining tissue expansion with a perforator flap for large tissue reconstruction can be successful with limited complications. This technique may allow a larger pliable skin flap that deserves further investigation.

Mesenchymal Stem Cells in Burn Wound Management

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

Bio-Multifunctional Sponges Containing Alginate/Chitosan/Sargassum Polysaccharides Promote the Healing of Full-Thickness Wounds

Creation of bio-multifunctional wound dressings with potent hemostatic, antibacterial, anti-inflammatory, and angiogenesis features for bolstering the healing of full-thickness wounds is sought after for clinical applications. We created bio-multifunctional composite sponges by coupling alginate and chitosan with Sargassum pallidum polysaccharides through electrostatic interactions, calcium ion (Ca2+) crosslinking, and lyophilization. Alginate/chitosan (AC) sponges with different concentrations of Sargassum pallidum polysaccharides were obtained and termed AC, ACS-1%, ACS-2.5%, and ACS-5%. ACS-1% and ACS-2.5% sponges exhibited uniform porosity, high water vapor transmission rate, high water absorption, as well as good hemostatic and antibacterial abilities. ACS-2.5% sponges facilitated wound closure and promoted angiogenesis and re-epithelialization in the dermis. These data suggest that ACS sponges containing a certain amount of Sargassum pallidum polysaccharides could be employed for treatment of full-thickness skin wounds.

Modulation of Mesenchymal Stem Cells for Enhanced Therapeutic Utility in Ischemic Vascular Diseases

Mesenchymal stem cells are multipotent stem cells isolated from various tissue sources, including but not limited to bone marrow, adipose, umbilical cord, and Wharton Jelly. Although cell-mediated mechanisms have been reported, the therapeutic effect of MSCs is now recognized to be primarily mediated via paracrine effects through the secretion of bioactive molecules, known as the “secretome”. The regenerative benefit of the secretome has been attributed to trophic factors and cytokines that play neuroprotective, anti-angiogenic/pro-angiogenic, anti-inflammatory, and immune-modulatory roles. The advancement of autologous MSCs therapy can be hindered when introduced back into a hostile/disease environment. Barriers include impaired endogenous MSCs function, limited post-transplantation cell viability, and altered immune-modulatory efficiency. Although secretome-based therapeutics have gained popularity, many translational hurdles, including the heterogeneity of MSCs, limited proliferation potential, and the complex nature of the secretome, have impeded the progress. This review will discuss the experimental and clinical impact of restoring the functional capabilities of MSCs prior to transplantation and the progress in secretome therapies involving extracellular vesicles. Modulation and utilization of MSCs–secretome are most likely to serve as an effective strategy for promoting their ultimate success as therapeutic modulators.

Promotion of Burn Wound Healing by Local Application of Adipose-Derived Mesenchymal Stem Cells: An Experimental Study

Background:The burn wound is one of the health problems in the world that affects physical and mental health. Today, adipose-derived mesenchymal stem cells (ADSCs) have received medical attention for their accessibility and the ability to reproduce and repair. The present study was designed to investigate the effect of ADSCs on burn wound healing. Methods : The present experimental study was performed on 36 male Wistar rats divided into 1 control group and 3 experimental groups. The second-degree burns with a radius of 10 mm were induced after anesthesia. ADSCs and Dulbecco's Modified Eagle Medium (DMEM) were injected into the dermis around the burn area in the ADSCs and DMEM groups, respectively. Silver sulfadiazine (SSD) ointment was applied topically once daily as the SSD group. The control group did not receive any treatment. The rats were evaluated for 21 days. Wound healing rate, histopathological parameters, and the number of fibroblasts were evaluated by the immunofluorescence technique and vascular endothelial growth factor and transforming growth factor β (TGF-β) gene expression by reverse transcription-polymerase chain reaction. The results were entered into SPSS software (SPSS Inc) and analyzed with 1-way analysis of variance and repeated measures analysis. Results: The number of fibroblasts, the number of vessels, TGF-β, and VEGF gene expression in the burn area were significantly higher in the ADSCs group than in the SSD, DMEM, and control groups. The results also showed that the amount of inflammation was significantly lower in the ADSCs group compared with the control group (p<0.001). Moreover, the percentage of wound recovery was significantly higher in the ADSCs group compared with other groups (p<0.001). Conclusion: ADSCs accelerate and improve burn wound healing by affecting fibroblasts, keratinocytes, and inflammatory cells as well as increasing the expression of the TGF-β and VEGF genes, and thus increase in angiogenesis.

Tailoring the proliferation of fibroblast cells by multiresponsive and thermosensitive stem cells composite F127 hydrogel containing folic acid.MgO:ZnO/chitosan hybrid microparticles for skin regeneration

In this study, biodegradable and thermosensitive F127 hydrogel containing folic acid.MgO:ZnO/chitosan hybrid particles (FMZC) was fabricated as a 3D mesenchymal stem cells (MSCs) delivery vehicle for regenerative medicine and wound healing purposes, in such a way to be responsive to lysozyme and UVA irradiation. The results showed that F127 hydrogel containing FMZC is a suitable and nontoxic construct for encapsulation of MSCs in the presence of lysozyme and UVA irradiation, bearing high stem cell viability and proliferation. The final hydrogel, MSC&FMZC, in response to lysozyme induced a higher proliferation rate and migration in human foreskin fibroblast cells (HFF). These phenomena were attributed to the released F.MgO:ZnO nanocomposites from chitosan microparticles and paracrine factors from MSCs within the hydrogel, resulting in synergistic biological effects. Moreover, lysozyme-treated MSC&FMZC hydrogel showed higher antibacterial and anti-biofilm activity against both Gram-positive and Gram-negative bacteria than bare hydrogel. However, a significant increase in the antibacterial activity of MSC&FMZC was observed as the treated bacteria were subjected to UVA irradiation owing to the photocatalytic activity of F.MgO:ZnO nanocomposites. Regarding the antibacterial activity and stimulating skin cell behavior of MSC&FMZC hydrogel that can promote the regenerative activities of skin, it could be considered as a promising scaffold for bacteria-accompanied wound healing.

Improved Mesenchymal Stem Cell Proliferation, Differentiation, Epithelial Transition, and Restrained Senescence on Hierarchically Patterned Porous Honey Silk Fibroin Scaffolds

We report a significant improvement of adipose-derived mesenchymal stem cells' (ADMSCs) biocompatibility and proliferation on hierarchically patterned porous honey-incorporated silk fibroin scaffolds fabricated using a combination of soft lithography and freeze-drying techniques. Parametric variations show enhanced surface roughness, swelling, and degradation rate with good pore interconnectivity, porosity, and mechanical strength for soft-lithographically fabricated biomimetic microdome arrays on the 2% honey silk fibroin scaffold (PHSF2) as compared to its other variants, which eventually made PHSF2 more comparable to the native environment required for stem cell adhesion and proliferation. PHSF2 also exhibits sustained honey release with remarkable antibacterial efficacy against methicillin-resistant Staphylococcus aureus (MRSA). Honey incorporation (biochemical cue) influences microdome structural features, that is, biophysical cues (height, width, and periodicity), which further allows ADMSCs pseudopods (filopodia) to grasp the microdomes for efficient cell-cell communication and cell-matrix interaction and regulates ADMSCs behavior by altering their cytoskeletal rearrangement and thereby increases the cellular spreading area and cell sheet formation. The synergistic effect of biochemical (honey) and biophysical (patterns) cues on ADMSCs studied by the nitro blue tetrazolium assay and DCFDA fluorescence spectroscopy reveals limited free radical generation within cells. Molecular expression studies show a decrease in p53 and p21 expressions validating ADMSCs senescence inhibition, which is further correlated with a decrease in cellular senescence-associated β galactosidase activity. We also show that an increase in CDH1 and CK19 molecular expressions along with an increase in SOX9, RUNX2, and PPARγ molecular expressions supported by PHSF2 justify the substrate's efficacy of underpinning mesenchymal to epithelial transition and multilineage trans-differentiation. This work highlights the fabrication of a naturally healing nutraceutical (honey)-embedded patterned porous stand-alone tool with the potential to be used as smart stem cells delivering regenerative healing implant.

An update on stem cells applications in burn wound healing

Burn wounds have proven to be capable of having a long lasting devastating effects on human body. Conventional therapeutic approaches are not up to the mark as they are unable to completely heal the burn wound easily and effectively. Major pitfalls of these treatments include hypertrophic scarring, contracture and necrosis. Presence of these limitations in the current therapies necessitate the search for a better and more efficient cure. Regenerative potency of stem cells in burn wound healing outweigh the traditional treatment procedures. The use of multiple kinds of stem cells are gaining interest due to their enhanced healing efficiency. Distinctions of stem cells include better and faster burn wound healing, decreased inflammation levels, less scar progression and fibrosis on site. In this review, we have discussed the wound-healing process, present methods used for stem cells administration, methods of enhancing stem cells potency and human studies. Pre-clinical and the clinical studies focused on the treatment of thermal and radiation burns using stem cells from 2003 till the present time have been enlisted. Studies shows that the use of stem cells on burn wounds, whether alone or by the help of a scaffold significantly improves healing. Homing of the stem cells at the wound site results in the re-epithelialization, angiogenesis, granulation, inhibition of apoptosis, and regeneration of skin appendages together with reduced infection rate in the human studies. Several studies on animals have shown that stem cells can effectively promote wound healing. Although more research is needed to find out the effectiveness of this treatment in patients with severe burn wounds.

Preparation of nano-hydroxyapatite/chitosan/tilapia skin peptides hydrogels and its burn wound treatment

There is an urgent need for wound dressings to treat partial-thickness burns. Hydrogels are a promising material that can maintain hydration to promote necrotic tissue removal. Tilapia peptides (TP) and hydroxyapatite (HA) were incorporated into chitosan system to prepare new types of hydrogels. The hydrogels were cross-linking by tannin (TA), which were developed to promote rapid wound healing in a New Zealand rabbit partial-thickness burn model. Nanohydroxyapatite (NHA) was synthesized by coprecipitation method, which made hydrogels have a highly porous structure comprised of interconnected pores, excellent water absorption and low hemolysis. Besides, the hydrogels showed excellent antimicrobial activities against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), as well as the cytocompatibility on endothelial cells. Moreover, the hydrogels promoted epithelial and dermal regeneration, reduce the expression of TNF-α and IL-6 and promote the skin regeneration by enhancing expression of collagen, STAT3, and VEGF.

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

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

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.

Skin regeneration is accelerated by a lower dose of multipotent mesenchymal stromal/stem cells-a paradigm change

Background

Multipotent mesenchymal stromal/stem cell (MSC) therapy is under investigation in promising (pre-)clinical trials for wound healing, which is crucial for survival; however, the optimal cell dosage remains unknown. The aim was to investigate the efficacy of different low-to-high MSC dosages incorporated in a biodegradable collagen-based dermal regeneration template (DRT) Integra®.

Methods

We conducted a porcine study (N = 8 Yorkshire pigs) and seeded between 200 and 2,000,000 cells/cm² of umbilical cord mesenchymal stromal/stem cells on the DRT and grafted it onto full-thickness burn excised wounds. On day 28, comparisons were made between the different low-to-high cell dose groups, the acellular control, a burn wound, and healthy skin.

Result

We found that the low dose range between 200 and 40,000 cells/cm² regenerates the full-thickness burn excised wounds most efficaciously, followed by the middle dose range of 200,000–400,000 cells/cm² and a high dose of 2,000,000 cells/cm². The low dose of 40,000 cells/cm² accelerated reepithelialization, reduced scarring, regenerated epidermal thickness superiorly, enhanced neovascularization, reduced fibrosis, and reduced type 1 and type 2 macrophages compared to other cell dosages and the acellular control.

Conclusion

This regenerative cell therapy study using MSCs shows efficacy toward a low dose, which changes the paradigm that more cells lead to better wound healing outcome.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-020-02131-6.

Efficacy assessment of mesenchymal stem cell transplantation for burn wounds in animals: a systematic review

Background

Clinically, severe burns remain one of the most challenging issues, but an ideal treatment is yet absent. Our purpose is to compare the efficacy of stem cell therapy in a preclinical model of burn wound healing.

Methods

Research reports on mesenchymal stem cells (MSCs) for burn wound healing were retrieved from 5 databases: PubMed, Embase, MEDLINE, Web of Science, and the Cochrane Library. The primary outcomes reported in this article include the un-healing rate of the wound area, the closure rate, and the wound area. Secondary outcomes included CD-31, vascular density, interleukin (IL)-10, thickness of eschar tissue, vascular endothelial growth factor (VEGF), and white blood cell count. Finally, a subgroup analysis was conducted to explore heterogeneity that potentially impacted the primary outcomes. A fixed-effects model with a 95% confidence interval (CI) was performed when no significant heterogeneity existed. Otherwise, a random-effects model was used. All data analysis was conducted by using Engauge Digitizer 10.8 and R software.

Results

Twenty eligible articles were finally included in the analysis. Stem cell therapy greatly improved the closure rate (2.00, 95% CI 0.52 to 3.48, p = 0.008) and compromised the wound area (− 2.36; 95% CI − 4.90 to 0.18; p = 0.069) rather than the un-healing rate of the wound area (− 11.10, 95% CI − 32.97 to 10.78, p = 0.320). Though p was 0.069, there was a trend toward shrinkage of the burn wound area after stem cell therapy. Vascular density (4.69; 95% CI 0.06 to 9.31; p = 0.047) and thickness of eschar tissue (6.56, 95% CI 1.15 to 11.98, p = 0.017) were also discovered to be significantly improved in the burn site of stem cell-treated animals. Moreover, we observed that animals in the stem cell group had an increased white blood cell count (0.84, 95% CI 0.01 to 1.66, p = 0.047) 5 days post treatment. Other indicators, such as VEGF (p = 0.381), CD-31 (p = 0.335) and IL-10 (p = 0.567), were not significantly impacted.

Conclusions

Despite limited data from preclinical trials, this meta-analysis suggests that stem cell therapy is curative in decreasing the burn wound area and provides some insights into future clinical studies of stem cell therapy for burns.

The effect of Ganoderma lucidum spore oil in early skin wound healing: interactions of skin microbiota and inflammation

The mushroom Ganoderma lucidum (G. lucidum Leyss. ex Fr.) Karst has been a traditional Chinese medicine for millennia. In this study, we isolated the Ganoderma lucidum spore oil (GLSO) and evaluated the effect of GLSO on skin burn wound healing and the underlying mechanisms. Mice were used to perform skin wound healing assay. Wound analysis was performed by photography, hematoxylin/eosin staining, Masson’s Trichrome staining and immunohistochemical analysis. Microbiota on the wounds were analyzed using the 16s rRNA sequence and quantitative statistics. The lipopolysaccharide (LPS) content was examined in skin wounds and serum using an enzyme-linked immunosorbent assay (ELISA). The expression of Toll-like receptor 4 (TLR4) and the relative levels of inflammatory cytokines were determined by qPCR and immunofluorescence assay. A pseudo-germfree mouse model treated with antibiotics was used to investigate whether GLSO accelerated skin burn wound healing through the skin microbiota. We found that GLSO significantly accelerated the process of skin wound healing and regulated the levels of gram-negative and gram-positive bacteria. Furthermore, GLSO reduced LPS and TLR4, and levels of some other related inflammatory cytokines. The assay with the pseudo-germfree mice model showed that GLSO had a significant acceleration on skin wound healing in comparison with antibiotic treatment. Thus, GLSO downregulated the inflammation by regulating skin microbiota to accelerate skin wound healing. These findings provide a scientific rationale for the potential therapeutic use of GLSO in skin burn injury.

Investigating the effects of walnut ointment on non-healing burn wounds

Effective treatments for non-healing burn wounds are an unmet need for 95% of burn sufferers. Approaches currently available to treat non-healing burn wounds are not satisfactory due to undesirable side-effects or expense. The anti-oxidation and antibacterial activities of walnuts are recommended for treating chronic diseases. Walnut ointment has been developed and successfully applied to treat non-healing burn wounds in our hospital for decades. We report herein a detailed retrospective case review examining patients' response to the walnut ointment. The walnut ointment has shortened healing time of non-healing burn wounds and improved clinical outcomes. In order to investigate the mechanism of action, walnut ointment has been applied on wounds of porcine full-thickness burn wound models. Histological and immunohistochemical analysis indicated our walnut ointment supports wound healing through promoting keratinocyte proliferation and differentiation. Taken together, we recommend the walnut ointment offers an effective and economical treatment for patients presenting with non-healing burn wounds.

Burns in the Elderly: Potential Role of Stem Cells

Burns in the elderly continue to be a challenge despite advances in burn wound care management. Elderly burn patients continue to have poor outcomes compared to the younger population. This is secondary to changes in the quality of the aged skin, leading to impaired wound healing, aggravated immunologic and inflammatory responses, and age-related comorbidities. Considering the fast-growing elderly population, it is imperative to understand the anatomic, physiologic, and molecular changes of the aging skin and the mechanisms involved in their wound healing process to prevent complications associated with burn wounds. Various studies have shown that stem cell-based therapies improve the rate and quality of wound healing and skin regeneration; however, the focus is on the younger population. In this paper, we start with an anatomical, physiological and molecular dissection of the elderly skin to understand why wound healing is delayed. We then review the potential use of stem cells in elderly burn wounds, as well as the mechanisms by which mesenchymal stem cell (MSCs)-based therapies may impact burn wound healing in the elderly. MSCs improve burn wound healing by stimulating and augmenting growth factor secretion and cell proliferation, and by modulating the impaired elderly immune response. MSCs can be used to expedite healing in superficial partial thickness burns and donor site wounds, improve graft take and prevent graft breakdown.