Topical Application of Conditioned Medium from Hypoxically Cultured Amnion-Derived Mesenchymal Stem Cells Promotes Wound Healing in Diabetic Mice

Hypoxic culture enhances the antimicrobial activity of amnion-derived mesenchymal stem cells, thereby reducing bacterial load and promoting wound healing in diabetic mice

BACKGROUND

Conditioned medium from amnion-derived mesenchymal stem cells (AMSCs) enhances wound healing, a process that is further improved under hypoxic culture conditions. Diabetic foot ulcers are difficult to treat and are frequently complicated by a high rate of bacterial infections, mainly Staphylococcus aureus, which can lead to limb amputation and death. Here, we topically applied conditioned medium from AMSCs cultured under hypoxic conditions to S. aureus-infected wounds in diabetic mice to investigate its effect on bacterial counts and wound healing.

METHODS

We prepared conditioned medium by culturing AMSCs under 21 % or 1 % O2 and investigated its effects on S. aureus. We infected skin wounds of diabetic mice with S. aureus and treated these with hydrogels containing the conditioned medium to examine its effect on bacterial inhibition and wound healing.

RESULTS

Conditioned medium from AMSCs cultured under 1 % O2 contained higher levels of the antimicrobial peptide LL-37. It significantly inhibited S. aureus growth in vitro, reduced bacterial counts in infected wounds, and facilitated wound closure in diabetic mice.

CONCLUSIONS

Hydrogels containing conditioned medium from hypoxically cultured AMSCs inhibited the growth of S. aureus and promoted wound healing in a mouse model of diabetic wounds.

Advancing wound healing by hydrogel-based dressings loaded with cell-conditioned medium: a systematic review

BACKGROUND

Wound healing represents a complex biological process, critically important in clinical practice due to its direct implication in a patient's recovery and quality of life. Conservative wound management frequently falls short in providing an ideal environment for the optimal tissue regeneration, often resulting in extended healing periods and elevated risk of infection and other complications. The emerging biomaterials, particularly hydrogels, have shown substantial promise in addressing these challenges by offering properties such as biocompatibility, biodegradability, and the ability to cure wound environment. Recent advancements have highlighted the therapeutic potential of integrating cell-derived conditioned medium (CM) into hydrogel matrices. Cell-derived CM represents a rich array of bioactive molecules, demonstrating significant efficacy in modulating cellular activities crucial for wound healing, including cellular proliferation, migration, and angiogenesis.

METHODS

The methodology of this review adheres to the standards set by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. The review includes a selection of studies published within the last five years, focusing on in vivo experiments involving various types of skin injuries treated with topically applied hydrogels loaded with CM (H-CM). The search strategy refers to the PICO framework and includes the assessment of study quality by CAMARADES tool.

RESULTS

The systematic review represents a detailed evaluation of H-CM dressings wound healing efficiency based on the experimental results of cell-based assays and animal wound models. The study targets to reveal wound healing capacity of H-CM dressings, and provides a comparative data analysis, limitations of methods and discussions of H-CM role in advancing the wound healing therapy.

CONCLUSIONS

The data presented demonstrate that H-CM is a promising material for advanced wound healing and regenerative medicine. These dressings possess proved in vitro/in vivo efficacy that highlights their strong clinical potential and paves the way to further investigations of H-CM formulations within clinical trials.

Molecular immunological mechanisms of impaired wound healing in diabetic foot ulcers (DFU), current therapeutic strategies and future directions

Diabetic foot ulcer (DFU) is a foremost cause of amputation in diabetic patients. Consequences of DFU include infections, decline in limb function, hospitalization, amputation, and in severe cases, death. Immune cells including macrophages, regulatory T cells, fibroblasts and other damage repair cells work in sync for effective healing and in establishment of a healthy skin barrier post-injury. Immune dysregulation during the healing of wounds can result in wound chronicity. Hyperglycemic conditions in diabetic patients influence the pathophysiology of wounds by disrupting the immune system as well as promoting neuropathy and ischemic conditions, making them difficult to heal. Chronic wound microenvironment is characterized by increased expression of matrix metalloproteinases, reactive oxygen species as well as pro-inflammatory cytokines, resulting in persistent inflammation and delayed healing. Novel treatment modalities including growth factor therapies, nano formulations, microRNA based treatments and skin grafting approaches have significantly augmented treatment efficiency, demonstrating creditable efficacy in clinical practices. Advancements in local treatments as well as invasive methodologies, for instance formulated wound dressings, stem cell applications and immunomodulatory therapies have been successful in targeting the complex pathophysiology of chronic wounds. This review focuses on elucidating the intricacies of emerging physical and non-physical therapeutic interventions, delving into the realm of advanced wound care and comprehensively summarizing efficacy of evidence-based therapies for DFU currently available.

Promising improvement in infected Wound Healing in Type two Diabetic rats by Combined effects of conditioned medium of human adipose-derived stem cells plus Photobiomodulation

BACKGROUND

We aimed to examine the accompanying and solo impacts of conditioned medium of human adipose-derived stem cells (h-ASC-COM) and photobiomodulation (PBM) on the maturation stage of an ischemic infected delayed-healing wound model (IIDHWM) of rats with type 2 diabetes (TIIDM).

RESULTS

Outcomes of the wound closure ratio (WCR) results, tensiometrical microbiological, and stereological assessment followed almost identical patterns. While the outcomes of h-ASC-COM + PBM, PBM only, and h-ASC-COM only regimes were significantly better for all evaluated methods than those of group 1(all, p < 0.001), PBM alone and h-ASC-COM + PBM therapy achieved superior results than h-ASC-COM only (ranged from p = 0.05 to p < 0.001). In terms of tensiometrical and stereological examinations, the results of h-ASC-COM + PBM experienced better results than the PBM only (all, p < 0.001).

CONCLUSIONS

h-ASC-COM + PBM, PBM, and h-ASC-COM cures expressively accelerated the maturation stage in the wound healing process of IIDHWM with MRSA in TIIDM rats by diminishing the inflammatory reaction, and the microbial flora of MRSA; and increasing wound strength, WCR, number of fibroblasts, and new blood vessels. While the h-ASC-COM + PBM and PBM were more suitable than the effect of h-ASC-COM, the results of h-ASC-COM + PBM were superior to PBM only.

Development of a simultaneous and noninvasive measuring method using high-frame rate videography and motion analysis software for the assessment of facial palsy recovery in a rat model

BACKGROUND

For the development of new therapeutic and reconstructive methods for facial nerve palsy, it is critical to validate them in animal models. This study developed a novel evaluation method using a high-speed camera and motion analysis software for rat facial paralysis models. The validity of the new method was verified using normal rats and rats with facial paralysis.

METHODS

The whisker movement was recorded using a high-frame video camera. The video files were processed using motion analysis software, and the angular velocities were measured. The score was calculated as the percentage of movement on the side that had palsy compared with the movement on the normal side. Normal rats were used to examine which of the four indices of angular velocity is appropriate for this evaluation method. Using this method, two types of facial nerve palsy models were compared. Furthermore, the three agents that were predicted to promote axon regeneration from previous studies were evaluated.

RESULTS

The two averages of the protraction and retraction movement velocities of the whiskers were considered as the most appropriate indicators for this new method. Compared with the saline group, all agent groups showed significant differences in the improvement of facial palsy recovery.

CONCLUSIONS

This method is an evaluation method for the effects of therapeutic intervention for facial nerve paralysis in real time without sacrificing animals.

Advances in the applications of mesenchymal stem cell-conditioned medium in ocular diseases

Mesenchymal stem cell-conditioned medium (MSC-CM), also known as secretome, is secreted by MSC and contains a variety of bioactive factors with anti-inflammatory, anti-apoptotic, neuroprotection, and proliferation effects. Increasing evidence proved that MSC-CM plays an important role in various diseases, including skin, bone, muscle, and dental diseases. However, the role of MSC-CM in ocular diseases is not quite clear, Therefore, this article reviewed the composition, biological functions, preparation, and characterization of MSC-CM and summarized current research advances in different sources of MSC-CM in corneal and retinal diseases, including dry eye, corneal epithelial damage, chemical corneal injury, retinitis pigmentosa (RP), anterior ischemic optic neuropathy (AION), diabetic retinopathy (DR), and other retinal degenerative changes. For these diseases, MSC-CM can promote cell proliferation, reduce inflammation and vascular leakage, inhibit retinal cell degeneration and apoptosis, protect corneal and retinal structures, and further improves visual function. Hence, we summarize the production, composition and biological functions of MSC-CM and focus on describing its mechanisms in the treatment of ocular diseases. Furthermore, we look at the unexplored mechanisms and further research directions for MSC-CM based therapy in ocular diseases.

Exosomes Derived from Human Amniotic Mesenchymal Stem Cells Facilitate Diabetic Wound Healing by Angiogenesis and Enrich Multiple lncRNAs

BACKGROUND

Diabetic wound healing remains a major challenge due to the impaired functionality of angiogenesis by persistent hyperglycemia. Mesenchymal stem cell exosomes are appropriate candidates for regulating the formation of angiogenesis in tissue repair and regeneration. Here, we explored the effects of exosomes derived from human amniotic mesenchymal stem cell (hAMSC-Exos) on the biological activities of human umbilical vein endothelial cells (HUVECs) treated with high glucose and on diabetic wound healing and investigate lncRNAs related to angiogenesis in hAMSC-Exos.

METHODS

hAMSCs and hAMSC-Exos were isolated and identified by flow cytometry or western blot. A series of functional assays such as cell counting kit-8, scratching, transwell and tube formation assays were performed to evaluate the potential effect of hAMSC-Exos on high glucose-treated HUVECs. The effect of hAMSC-Exos on diabetic wound healing were tested by measuring wound closure rates and immunohistochemical staining of CD31. Subsequently, the lncRNAs profiles in hAMSC-Exos and hAMSCs were examined to screen the lncRNAs related to angiogenesis.

RESULTS

The isolated hAMSC-Exos had a size range of 30-150 nm and were positive for CD9, CD63 and CD81. The hAMSC-Exos facilitate the functional properties of high glucose-treated HUVECs including the proliferation, migration and the angiogenic activities as well as wound closure and angiogenesis in diabetic wound. hAMSC-Exos were enriched lncRNAs that related to angiogenesis, including PANTR1, H19, OIP5-AS1 and NR2F1-AS1.

CONCLUSION

Our findings demonstrated hAMSC-Exos facilitate diabetic wound healing by angiogenesis and contain several exosomal lncRNAs related to angiogenesis, which may represent a promising strategy for diabetic wound healing.

Emerging roles of mesenchymal stem cell therapy in patients with critical limb ischemia

Critical limb ischemia (CLI), the terminal stage of peripheral arterial disease (PAD), is characterized by an extremely high risk of amputation and vascular issues, resulting in severe morbidity and mortality. In patients with severe limb ischemia with no alternative therapy options, such as endovascular angioplasty or bypass surgery, therapeutic angiogenesis utilizing cell-based therapies is vital for increasing blood flow to ischemic regions. Mesenchymal stem cells (MSCs) are currently considered one of the most encouraging cells as a regenerative alternative for the surgical treatment of CLI, including restoring tissue function and repairing ischemic tissue via immunomodulation and angiogenesis. The regenerative treatments for limb ischemia based on MSC therapy are still considered experimental. Despite recent advances in preclinical and clinical research studies, it is not recommended for regular clinical use. In this study, we review the immunomodulatory features of MSC besides the current understanding of different sources of MSC in the angiogenic treatment of CLI subjects and their potential applications as therapeutic agents. Specifically, this paper concentrates on the most current clinical application issues, and several recommendations are provided to improve the efficacy of cell therapy for CLI patients.

Stem Cells and Angiogenesis: Implications and Limitations in Enhancing Chronic Diabetic Foot Ulcer Healing

Nonhealing diabetic foot ulcers (DFUs) are a continuing clinical issue despite the improved treatment with wound debridement, off-loading the ulcer, medication, wound dressings, and preventing infection by keeping the ulcer clean. Wound healing is associated with granulation tissue formation and angiogenesis favoring the wound to enter the resolution phase of healing followed by healing. However, chronic inflammation and reduced angiogenesis in a hyperglycemic environment impair the normal healing cascade and result in chronically non-healing diabetic foot ulcers. Promoting angiogenesis is associated with enhanced wound healing and using vascular endothelial growth factors has been proven beneficial to promote neo-angiogenesis. However, still, nonhealing DFUs persist with increased risks of amputation. Regenerative medicine is an evolving branch applicable in wound healing with the use of stem cells to promote angiogenesis. Various studies have reported promising results, but the associated limitations need in-depth research. This article focuses on summarizing and critically reviewing the published literature since 2021 on the use of stem cells to promote angiogenesis and enhance wound healing in chronic non-healing DFUs.

Preconditioning Methods to Improve Mesenchymal Stromal Cell-Derived Extracellular Vesicles in Bone Regeneration—A Systematic Review

Simple Summary

The evidence of the therapeutic effects of mesenchymal stromal cells (MSCs), so-called stem cells, in several diseases relies mostly on the substances they secrete, including their extracellular vesicles (EVs). EVs are an important component of cell communication and they carry a cargo that is similar to their parent cell. Cells respond differently based on their microenvironment, and so it is expected that the therapeutic potential of these vesicles can be modulated by the enrichment of their parent cell microenvironment. With this in mind, we conducted a systematic search for papers that preconditioned MSCs and collected their EVs to assess their potential to favor bone formation. The results showed different methods for MSC preconditioning, including chemical induction, culture conditions, and genetic modifications. All methods were able to improve the therapeutic effects of the derived EVs for bone formation. However, the heterogeneity among studies—regarding the type of cell, EV concentration, and scaffolds—made it difficult to compare fairly the types of preconditioning methods. In summary, the microenvironment greatly influences MSCs, and using preconditioning methods can potentially improve the therapeutic effects of their derived EVs in bone regeneration and other bone diseases.

Abstract

Mesenchymal stromal cells (MSCs) have long been used in research for bone regeneration, with evidence of their beneficial properties. In the segmental area of MSC-based therapies, MSC-derived extracellular vesicles (EVs) have also shown great therapeutic effects in several diseases, including bone healing. This study aimed to assess whether the conditioning of MSCs improves the therapeutic effects of their derived extracellular vesicles for bone regeneration. Electronic research was performed until February 2021 to recover the studies in the following databases: PubMed, Scopus, and Web of Science. The studies were screened based on the inclusion criteria. Relevant information was extracted, including in vitro and in vivo experiments, and the animal studies were evaluated for risk of bias by the SYRCLE tool. A total of 463 studies were retrieved, and 18 studies met the inclusion criteria (10 studies for their in vitro analysis, and 8 studies for their in vitro and in vivo analysis). The conditioning methods reported included: osteogenic medium; dimethyloxalylglycine; dexamethasone; strontium-substituted calcium silicate; hypoxia; 3D mechanical microenvironment; and the overexpression of miR-375, bone morphogenetic protein-2, and mutant hypoxia-inducible factor-1α. The conditioning methods of MSCs in the reported studies generate exosomes able to significantly promote bone regeneration. However, heterogeneity regarding cell source, conditioning method, EV isolation and concentration, and defect model was observed among the studies. The different conditioning methods reported in this review do improve the therapeutic effects of MSC-derived EVs for bone regeneration, but they still need to be addressed in larger animal models for further clinical application.