Human umbilical cord blood-derived mesenchymal stromal cells and small intestinal submucosa hydrogel composite promotes combined radiation-wound healing of mice

Complications after Prostate Cancer Treatment: Pathophysiology and Repair of Post-Radiation Urethral Stricture Disease

Radiation therapy (RT) in the management of pelvic cancers remains a clinical challenge to urologists given the sequelae of urethral stricture disease secondary to fibrosis and vascular insults. The objective of this review is to understand the physiology of radiation-induced stricture disease and to educate urologists in clinical practice regarding future prospective options clinicians have to deal with this condition. The management of post-radiation urethral stricture consists of conservative, endoscopic, and primary reconstructive options. Endoscopic approaches remain an option, but with limited long-term success. Despite concerns with graft take, reconstructive options such as urethroplasties in this population with buccal grafts have shown long-term success rates ranging from 70 to 100%. Robotic reconstruction is augmenting previous options with faster recovery times. Radiation-induced stricture disease is challenging with multiple interventions available, but with successful outcomes demonstrated in various cohorts including urethroplasties with buccal grafts and robotic reconstruction.

Multifunctional Extracellular Matrix Hydrogel with Self-Healing Properties and Promoting Angiogenesis as an Immunoregulation Platform for Diabetic Wound Healing

Treating chronic wounds is a global challenge. In diabetes mellitus cases, long-time and excess inflammatory responses at the injury site may delay the healing of intractable wounds. Macrophage polarization (M1/M2 types) can be closely associated with inflammatory factor generation during wound healing. Quercetin (QCT) is an efficient agent against oxidation and fibrosis that promotes wound healing. It can also inhibit inflammatory responses by regulating M1-to-M2 macrophage polarization. However, its limited solubility, low bioavailability, and hydrophobicity are the main issues restricting its applicability in wound healing. The small intestinal submucosa (SIS) has also been widely studied for treating acute/chronic wounds. It is also being extensively researched as a suitable carrier for tissue regeneration. As an extracellular matrix, SIS can support angiogenesis, cell migration, and proliferation, offering growth factors involved in tissue formation signaling and assisting wound healing. We developed a series of promising biosafe novel diabetic wound repair hydrogel wound dressings with several effects, including self-healing properties, water absorption, and immunomodulatory effects. A full-thickness wound diabetic rat model was constructed for in vivo assessment of QCT@SIS hydrogel, in which hydrogels achieved a markedly increased wound repair rate. Their effect was determined by the promotion of the wound healing process, the thickness of granulation tissue, vascularization, and macrophage polarization during wound healing. At the same time, we injected the hydrogel subcutaneously into healthy rats to perform histological analyses of sections of the heart, spleen, liver, kidney, and lung. We then tested the biochemical index levels in serum to determine the biological safety of the QCT@SIS hydrogel. In this study, the developed SIS showed convergence of biological, mechanical, and wound-healing capabilities. Here, we focused on constructing a self-healing, water-absorbable, immunomodulatory, and biocompatible hydrogel as a synergistic treatment paradigm for diabetic wounds by gelling the SIS and loading QCT for slow drug release.

Advances in mesenchymal stem/stromal cell-based therapy and their extracellular vesicles for skin wound healing

Wound healing is a dynamic and complicated process containing overlapping phases. Presently, definitive therapy is not available, and the investigation into optimal wound care is influenced by the efficacy and cost-effectiveness of developing therapies. Accumulating evidence demonstrated the potential role of mesenchymal stem/stromal cell (MSC) therapy in several tissue injuries and diseases due to their high proliferation and differentiation abilities along with an easy collection procedure, low tumorigenesis, and immuno-privileged status. MSCs have also accelerated wound repair in all phases through their advantageous properties, such as accelerating wound closure, improving re-epithelialization, elevating angiogenesis, suppressing inflammation, and modulating extracellular matrix (ECM) remodeling. In addition, the beneficial therapeutic impacts of MSCs are largely associated with their paracrine functions, including extracellular vesicles (EVs). Exosomes and microvesicles are the two main subgroups of EVs. These vesicles are heterogeneous bilayer membrane structures that contain several proteins, lipids, and nucleic acids. EVs have emerged as a promising alternative to stem cell-based therapies because of their lower immunogenicity, tumorigenicity, and ease of management. MSCs from various sources have been widely investigated in skin wound healing and regeneration. Considering these features, in this review, we highlighted recent studies that the investigated therapeutic potential of various MSCs and MSC-EVs in skin damages and wounds.

The Use of Hydrogel-Based Materials for Radioprotection

Major causes of the radiation-induced disease include nuclear accidents, war-related nuclear explosions, and clinical radiotherapy. While certain radioprotective drug or bioactive compounds have been utilized to protect against radiation-induced damage in preclinical and clinical settings, these strategies are hampered by poor efficacy and limited utilization. Hydrogel-based materials are effective carriers capable of enhancing the bioavailability of compounds loaded therein. As they exhibit tunable performance and excellent biocompatibility, hydrogels represent promising tools for the design of novel radioprotective therapeutic strategies. This review provides an overview of common approaches to radioprotective hydrogel preparation, followed by a discussion of the pathogenesis of radiation-induced disease and the current states of research focused on using hydrogels to protect against these diseases. These findings ultimately provide a foundation for discussions of the challenges and future prospects associated with the use of radioprotective hydrogels.

Convergence of Biofabrication Technologies and Cell Therapies for Wound Healing

BACKGROUND

Cell therapy holds great promise for cutaneous wound treatment but presents practical and clinical challenges, mainly related to the lack of a supportive and inductive microenvironment for cells after transplantation. Main: This review delineates the challenges and opportunities in cell therapies for acute and chronic wounds and highlights the contribution of biofabricated matrices to skin reconstruction. The complexity of the wound healing process necessitates the development of matrices with properties comparable to the extracellular matrix in the skin for their structure and composition. Over recent years, emerging biofabrication technologies have shown a capacity for creating complex matrices. In cell therapy, multifunctional material-based matrices have benefits in enhancing cell retention and survival, reducing healing time, and preventing infection and cell transplant rejection. Additionally, they can improve the efficacy of cell therapy, owing to their potential to modulate cell behaviors and regulate spatiotemporal patterns of wound healing.

CONCLUSION

The ongoing development of biofabrication technologies promises to deliver material-based matrices that are rich in supportive, phenotype patterning cell niches and are robust enough to provide physical protection for the cells during implantation.

Locally injected Mesenchymal Stem Cells optimize angiogenesis by regulating VEGF and CD31 expression in duodenal perforation

Background

Duodenal perforation is considered as one of gastrointestinal emergency with high morbidity and mortality rate. The MSCs have the ability to improve wound healing by releasing several growth factors and anti-inflammatory cytokines to promote the angiogenesis process. This study aimed to investigate the role of MSCs in duodenal perforation wound healing.

Methods

MSCs were isolated from rat umbilical cord and injected into duodenal wound site at doses of 1.5x10 [(Putra et al., 2018) 66 cells for T1 group and 3x10 [(Putra et al., 2018) 66 cells for T2 group. The control group was treated by local injection of normal saline. The VEGF levels were measured by Western blot, while CD31 expression was analyzed using immunohistochemistry staining. All examinations were assessed on days 3 and 7.

Results

Results showed a significant increase in VEGF and CD31 expression on days 3 and 7 (p < 0,05). The VEGF level was significantly decreased on day 7 compared to day 3.

Conclusion

The administration of MSCs improved the angiogenesis process in duodenal perforation by enhancing VEGF and CD31 expression.

•

Duodenal perforation is considered as one of gastrointestinal emergency with high morbidity and mortality rate.

•

The MSCs have the ability to improve wound healing by releasing several growth factors and anti-inflammatory cytokines to promote the angiogenesis process.

•

This study aimed to investigate the role of MSCs in duodenal perforation wound healing.

•

Results showed a significant increase in VEGF and CD31 expression on days 3 and 7.

•

The administration of MSCs improved the angiogenesis process in duodenal perforation.

Urine-Derived Stem Cells for Epithelial Tissues Reconstruction and Wound Healing

Epithelial tissue injury can occur on any surface site of the body, particularly in the skin or urethral mucosa tissue, due to trauma, infection, inflammation, and toxic compounds. Both internal and external body epithelial tissue injuries can significantly affect patients’ quality of life, increase healthcare spending, and increase the global economic burden. Transplantation of epithelial tissue grafts is an effective treatment strategy in clinical settings. Autologous bio-engineered epithelia are common clinical skin substitutes that have the specific advantages of avoiding tissue rejection, obviating ethical concerns, reducing the risk of infection, and decreasing scarring compared to donor grafts. However, epithelial cells are often obtained from the individual’s skin and mucosa through invasive methods, which cause further injury or damage. Urine-derived stem cells (USC) of kidney origin, obtained via non-invasive acquisition, possess high stemness properties, self-renewal ability, trophic effects, multipotent differentiation potential, and immunomodulatory ability. These cells show versatile potential for tissue regeneration, with extensive evidence supporting their use in the repair of epidermal and urothelial injuries. We discuss the collection, isolation, culture, characterization, and differentiation of USC. We also discuss the use of USC for cellular therapies as well as the administration of USC-derived paracrine factors for epidermal and urothelial tissue repair. Specifically, we will discuss 3D constructions involving multiple types of USC-loaded hydrogels and USC-seeded scaffolds for use in cosmetic production testing, drug development, and disease modeling. In conclusion, urine-derived stem cells are a readily accessible autologous stem cell source well-suited for developing personalized medical treatments in epithelial tissue regeneration and drug testing.

Stem Cell-Mediated Angiogenesis in Skin Tissue Engineering and Wound Healing

The timely management of skin wounds has been an unmet clinical need for centuries. While there have been several attempts to accelerate wound healing and reduce the cost of hospitalisation and the healthcare burden, there remains a lack of efficient and effective wound healing approaches. In this regard, stem cell‐based therapies have garnered an outstanding position for the treatment of both acute and chronic skin wounds. Stem cells of different origins (e.g., embryo‐derived stem cells) have been utilised for managing cutaneous lesions; specifically, mesenchymal stem cells (MSCs) isolated from foetal (umbilical cord) and adult (bone marrow) tissues paved the way to more satisfactory outcomes. Since angiogenesis plays a critical role in all four stages of normal wound healing, recent therapeutic approaches have focused on utilising stem cells for inducing neovascularisation. In fact, stem cells can promote angiogenesis via either differentiation into endothelial lineages or secreting pro‐angiogenic exosomes. Furthermore, particular conditions (e.g., hypoxic environments) can be applied in order to boost the pro‐angiogenic capability of stem cells before transplantation. For tissue engineering and regenerative medicine applications, stem cells can be combined with specific types of pro‐angiogenic biocompatible materials (e.g., bioactive glasses) to enhance the neovascularisation process and subsequently accelerate wound healing. As such, this review article summarises such efforts emphasising the bright future that is conceivable when using pro‐angiogenic stem cells for treating acute and chronic skin wounds.

Limited efficacy of adipose stromal cell secretome-loaded skin-derived hydrogels to augment skin flap regeneration in rats

Insufficient vascularization is a recurring cause of impaired pedicled skin flap healing. The administration of adipose tissue-derived stromal cells' (ASC) secretome is a novel approach to augment vascularization. Yet, the secretome comprised soluble factors that require a sustained release vehicle to increase residence time. We hypothesized that administration of a hydrogel derived from decellularized extracellular matrix (ECM) of porcine skin with bound trophic factors from ASCs, enhances skin flap viability and wound repair in a rat model. Porcine skin was decellularized and pepsin-digested to form a hydrogel at 37°C. Conditioned medium (CMe) of human ASC was collected, concentrated twentyfold and mixed with the hydrogel. Sixty Wistar rats were included. A dorsal skin flap (caudal based) of 3 x 10 cm was elevated for topical application of: DMEM medium (group I), a pre-hydrogel with or without ASC CMe (group II and III) or ASC CMe (group IV). After 7, 14 and 28 days, perfusion was measured and skin flaps were harvested for wound healing assessment and immunohistochemical analysis. Decellularized skin ECM hydrogel contained negligible amounts of DNA (11.6 ± 0.6 ng/mg), was noncytotoxic and well-tolerated by rats. Irrespective of ASC secretome, ECM hydrogel application resulted macroscopically and microscopically in similar dermal wound healing in terms of proliferation, immune response and matrix remodeling as the control group. However, ASC CMe alone increased vessel density after seven days. Concluding, porcine skin derived ECM hydrogels loaded with ASC secretome are non-cytotoxic but demand optimization to significantly augment wound healing of skin flaps.

Functional extracellular matrix hydrogel modified with MSC-derived small extracellular vesicles for chronic wound healing

OBJECTIVES

Diabetic wound healing remains a global challenge in the clinic and in research. However, the current medical dressings are difficult to meet the demands. The primary goal of this study was to fabricate a functional hydrogel wound dressing that can provide an appropriate microenvironment and supplementation with growth factors to promote skin regeneration and functional restoration in diabetic wounds.

MATERIALS AND METHODS

Small extracellular vesicles (sEVs) were bound to the porcine small intestinal submucosa-based hydrogel material through peptides (SC-Ps-sEVs) to increase the content and achieve a sustained release. NIH3T3 cell was used to evaluate the biocompatibility and the promoting proliferation, migration and adhesion abilities of the SC-Ps-sEVs. EA.hy926 cell was used to evaluate the stimulating angiogenesis of SC-Ps-sEVs. The diabetic wound model was used to investigate the function/role of SC-Ps-sEVs hydrogel in promoting wound healing.

RESULTS

A functional hydrogel wound dressing with good mechanical properties, excellent biocompatibility and superior stimulating angiogenesis capacity was designed and facilely fabricated, which could effectively enable full-thickness skin wounds healing in diabetic rat model.

CONCLUSIONS

This work led to the development of SIS, which shows an unprecedented combination of mechanical, biological and wound healing properties. This functional hydrogel wound dressing may find broad utility in the field of regenerative medicine and may be similarly useful in the treatment of wounds in epithelial tissues, such as the intestine, lung and liver.

HATMSC Secreted Factors in the Hydrogel as a Potential Treatment for Chronic Wounds-In Vitro Study

Mesenchymal stem cells (MSCs) can improve chronic wound healing; however, recent studies suggest that the therapeutic effect of MSCs is mediated mainly through the growth factors and cytokines secreted by these cells, referred to as the MSC secretome. To overcome difficulties related to the translation of cell therapy into clinical use such as efficacy, safety and cost, we propose a hydrogel loaded with a secretome from the recently established human adipose tissue mesenchymal stem cell line (HATMSC2) as a potential treatment for chronic wounds. Biocompatibility and biological activity of hydrogel-released HATMSC2 supernatant were investigated in vitro by assessing the proliferation and metabolic activity of human fibroblast, endothelial cells and keratinocytes. Hydrogel degradation was measured using hydroxyproline assay while protein released from the hydrogel was assessed by interleukin-8 (IL-8) and macrophage chemoattractant protein-1 (MCP-1) ELISAs. Pro-angiogenic activity of the developed treatment was assessed by tube formation assay while the presence of pro-angiogenic miRNAs in the HATMSC2 supernatant was investigated using real-time RT-PCR. The results demonstrated that the therapeutic effect of the HATMSC2-produced factors is maintained following incorporation into collagen hydrogel as confirmed by increased proliferation of skin-origin cells and improved angiogenic properties of endothelial cells. In addition, HATMSC2 supernatant revealed antimicrobial activity, and which therefore, in combination with the hydrogel has a potential to be used as advanced wound-healing dressing.

Extracellular matrix-derived hydrogels to augment dermal wound healing: a systematic review

BACKGROUND

Chronic, non-healing, dermal wounds form a worldwide medical problem with limited and inadequate treatment options and high societal burden and costs. With the advent of regenerative therapies exploiting extracellular matrix (ECM) components, its efficacy to augment wound healing is to be explored. This systematic review was performed to assess and compare the current therapeutic efficacy of ECM hydrogels on dermal wound healing.

METHODS

The electronic databases of (Embase, Medline Ovid, Cochrane Central) were searched for in vivo and clinical studies on the therapeutic effect of ECM-composed hydrogels on dermal wound healing (13th of April 2021). Two reviewers selected studies independently. Studies were assessed based on ECM content, ECM hydrogel composition, additives and wound healing outcomes such as wound size, angiogenesis and complications.

RESULTS

Of the 2102 publications, nine rodent-based studies were included while clinical studies were not published at the time of the search. Procedures to decellularize tissue or cultured cells and subsequently generate hydrogels were highly variable and in demand of standardization. ECM hydrogels with or without additives reduced wound size and also seem to enhance angiogenesis. Serious complications were not reported.

CONCLUSION

To date, preclinical studies preclude to draw firm conclusions on the efficacy and working mechanism of ECM-derived hydrogels on dermal wound healing. The use of ECM hydrogels can be considered safe. Standardization of decellularization protocols and implementation of quality and cytotoxicity controls will enable obtaining a generic and comparable ECM product.

Wound healing potential of human umbilical cord mesenchymal stem cell conditioned medium: An in vitro and in vivo study in diabetes-induced rats

Background and Aim:

Human umbilical cord mesenchymal stem cells (hUC-MSCs) and its conditioned medium (CM) promote wound healing. This study investigated the wound healing potential of hUC-MSC CM in vitro and in vivo using diabetic animal models.

Materials and Methods:

The CM from hUC-MSC CM prepared under hypoxic conditions (hypoxic hUC-MSC) was evaluated for stimulating rat fibroblast growth, collagen production (in vitro), and wound healing in animal models (in vivo). An excision wound on the dorsal side of the diabetes-induced rats was established, and the rats were randomly divided into non-treatment, antibiotic, and hypoxic hUC-MSC CM groups. The cell number of fibroblasts and collagen secretion was evaluated and compared among the groups in an in vitro study. By contrast, wound size reduction, width of re-epithelialization, and the collagen formation area were assessed and compared among the groups in an in vivo study.

Results:

CM under hypoxic conditions contained a higher concentration of wound healing-related growth factors. Hypoxic hUC-MSC CM could facilitate fibroblast cell growth and collagen synthesis, although not significant compared with the control group. Re-epithelialization and collagen production were higher in the hUC-MSC CM group than in the antibiotic and non-treatment groups.

Conclusion:

Hypoxic hUC-MSC CM possessed more positive effects on the wound healing process based on re-epithelialization and collagen formation than antibiotic treatment did.

Dichotomic Potency of IFNγ Licensed Allogeneic Mesenchymal Stromal Cells in Animal Models of Acute Radiation Syndrome and Graft Versus Host Disease

Mesenchymal stromal cells (MSCs) are being tested as a cell therapy in clinical trials for dozens of inflammatory disorders, with varying levels of efficacy reported. Suitable and robust preclinical animal models for testing the safety and efficacy of different types of MSC products before use in clinical trials are rare. We here introduce two highly robust animal models of immune pathology: 1) acute radiation syndrome (ARS) and 2) graft versus host disease (GvHD), in conjunction with studying the immunomodulatory effect of well-characterized Interferon gamma (IFNγ) primed bone marrow derived MSCs. The animal model of ARS is based on clinical grade dosimetry precision and bioluminescence imaging. We found that allogeneic MSCs exhibit lower persistence in naïve compared to irradiated animals, and that intraperitoneal infusion of IFNγ prelicensed allogeneic MSCs protected animals from radiation induced lethality by day 30. In direct comparison, we also investigated the effect of IFNγ prelicensed allogeneic MSCs in modulating acute GvHD in an animal model of MHC major mismatched bone marrow transplantation. Infusion of IFNγ prelicensed allogeneic MSCs failed to mitigate acute GvHD. Altogether our results demonstrate that infused IFNγ prelicensed allogeneic MSCs protect against lethality from ARS, but not GvHD, thus providing important insights on the dichotomy of IFNγ prelicensed allogenic MSCs in well characterized and robust animal models of acute tissue injury.

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.

Radiobiological Studies of Microvascular Damage through In Vitro Models: A Methodological Perspective

Ionizing radiation (IR) is used in radiotherapy as a treatment to destroy cancer. Such treatment also affects other tissues, resulting in the so-called normal tissue complications. Endothelial cells (ECs) composing the microvasculature have essential roles in the microenvironment's homeostasis (ME). Thus, detrimental effects induced by irradiation on ECs can influence both the tumor and healthy tissue. In-vitro models can be advantageous to study these phenomena. In this systematic review, we analyzed in-vitro models of ECs subjected to IR. We highlighted the critical issues involved in the production, irradiation, and analysis of such radiobiological in-vitro models to study microvascular endothelial cells damage. For each step, we analyzed common methodologies and critical points required to obtain a reliable model. We identified the generation of a 3D environment for model production and the inclusion of heterogeneous cell populations for a reliable ME recapitulation. Additionally, we highlighted how essential information on the irradiation scheme, crucial to correlate better observed in vitro effects to the clinical scenario, are often neglected in the analyzed studies, limiting the translation of achieved results.

Use of MSCs and MSC-educated macrophages to mitigate hematopoietic acute radiation syndrome

Purpose of Review

Innovative and minimally toxic treatment approaches are sorely needed for the prevention and treatment of hematopoietic acute radiation syndrome (H-ARS). Cell therapies have been increasingly studied for their potential use as countermeasures for accidental and intentional ionizing radiation exposures which can lead to fatal ARS. Mesenchymal stem/stromal cells (MSCs) are a cell therapy that have shown promising results in preclinical studies of ARS, and are being developed in clinical trials specifically for H-ARS. MSCs, MSC-educated macrophages (MEMs) and MSC-exosome educated macrophages (EEMs) all have the potential to be used as adoptive cell therapies for H-ARS. Here we review how MSCs have been reported to mitigate inflammation from radiation injury while also stimulating hematopoiesis during ARS.

Recent findings

We discuss emerging work with immune cell subsets educated by MSCs, including MEMs and EEMs, in promoting hematopoiesis in xenogeneic models of ARS. We also discuss the first placental-derived MSC product to enter phase I trials, PLX-R18, and the challenges faced by bringing MSC and other cell therapies into the clinic for treating ARS.

Summary

Although MSCs, MEMs and EEMs are potential cell therapy candidates in promoting hematopoietic HRS, challenges persist in translational clinical development of these products to the clinic. Whether any of these cellular therapies will be sufficient as stand-alone therapies to mitigate H-ARS or if they will be a bridging therapy that insures survival until a curative allogeneic hematopoietic stem cell transplant can be performed are the key questions that will have to be answered.

RNAseq profiling of circRNA expression in radiation-treated A549 cells and bioinformatics analysis of radiation-related circRNA-miRNA networks

With the development of new biochemical and computational methods, circular RNAs (circRNAs) have been identified as microRNA sponges. circRNAs are associated with many diseases, particularly cancer. The present study aimed to investigate the expression profile of circRNAs in irradiated A549 lung cancer cells using high-throughput sequencing. Bioinformatics analyses were used to examine the potential functions of circRNAs. RNA sequencing data demonstrated that 1,875 circRNA targets were differentially expressed in A549 cells in response to irradiation. A total of 30 circRNAs were upregulated and 37 circRNAs were downregulated significantly in irradiation-treated A549 cells (fold change ≥2.0; P<0.05). The top 5 upregulated and downregulated circRNAs were successfully validated by reverse transcription-quantitative PCR. In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that differentially expressed circRNAs might be pivotal in biological irradiation responses to irradiation. circRNA-microRNA co-expression networks highlighted the biological significance of circRNA_0002174 and circRNA_0036627, which require further study. In conclusion, the present study is, to the best of the authors' knowledge, the first to describe the differentially expressed profile of circRNAs in response to irradiation in A549 cells. These results provide a new perspective to elucidate insight into the molecular mechanisms by which A549 cells respond to radiation, and a basis for a more in-depth analysis of the potential application of circRNAs in the treatment of lung cancer therapy.

Mesenchymal Stem Cells for Chronic Wound Healing: Current Status of Preclinical and Clinical Studies

Healing skin wounds with anatomic and functional integrity, especially under chronic pathological conditions, remain an enormous challenge. Due to their outstanding regenerative potential, mesenchymal stem cells (MSCs) have been explored in many studies to determine the healing ability for difficult-to-treat diseases. In this article, we review current animal studies and clinical trials of MSC-based therapy for chronic wounds, and discuss major challenges that confront future clinical applications. We found that a wealth of animal studies have revealed the versatile roles and the benefits of MSCs for chronic wound healing. MSC treatment results in enhanced angiogenesis, facilitated reepithelialization, improved granulation, and accelerated wound closure. There are some evidences of the transdifferentiation of MSCs into skin cells. However, the healing effect of MSCs depends primarily on their paracrine actions, which alleviate the harsh microenvironment of chronic wounds and regulate local cellular responses. Consistent with the findings of preclinical studies, some clinical trials have shown improved wound healing after transplantation of MSCs in chronic wounds, mainly lower extremity ulcers, pressure sores, and radiation burns. However, there are some limitations in these clinical trials, especially a small number of patients and imperfect methodology. Therefore, to better define the safety and efficiency of MSC-based wound therapy, large-scale controlled multicenter trials are needed in the future. In addition, to build a robust pool of clinical evidence, standardized protocols, especially the cultivation and quality control of MSCs, are recommended. Altogether, based on current data, MSC-based therapy represents a promising treatment option for chronic wounds. Impact statement Chronic wounds persist as a significant health care problem, particularly with increasing number of patients and the lack of efficient treatments. The main goal of this article is to provide an overview of current status of mesenchymal stem cell (MSC)-based therapy for chronic wounds. The roles of MSCs in skin wound healing, as revealed in a large number of animal studies, are detailed. A critical view is made on the clinical application of MSCs for lower extremity ulcers, pressure sores, and radiation burns. Main challenges that confront future clinical applications are discussed, which hopefully contribute to innovations in MSC-based wound treatment.

Surface modification of small intestine submucosa in tissue engineering

With the development of tissue engineering, the required biomaterials need to have the ability to promote cell adhesion and proliferation in vitro and in vivo. Especially, surface modification of the scaffold material has a great influence on biocompatibility and functionality of materials. The small intestine submucosa (SIS) is an extracellular matrix isolated from the submucosal layer of porcine jejunum, which has good tissue mechanical properties and regenerative activity, and is suitable for cell adhesion, proliferation and differentiation. In recent years, SIS is widely used in different areas of tissue reconstruction, such as blood vessels, bone, cartilage, bladder and ureter, etc. This paper discusses the main methods for surface modification of SIS to improve and optimize the performance of SIS bioscaffolds, including functional group bonding, protein adsorption, mineral coating, topography and formatting modification and drug combination. In addition, the reasonable combination of these methods also offers great improvement on SIS surface modification. This article makes a shallow review of the surface modification of SIS and its application in tissue engineering.

Radiation-induced intestinal damage: latest molecular and clinical developments

Aim: To systematically review the prophylactic and therapeutic interventions for reducing the incidence or severity of intestinal symptoms among cancer patients receiving radiotherapy. Materials & methods: A literature search was conducted in the PubMed database using various search terms, including 'radiation enteritis', 'radiation enteropathy', 'radiation-induced intestinal disease', 'radiation-induced intestinal damage' and 'radiation mucositis'. The search was limited to in vivo studies, clinical trials and meta-analyses published in English with no limitation on publication date. Other relevant literature was identified based on the reference lists of selected studies. Results: The pathogenesis of acute and chronic radiation-induced intestinal damage as well as the prevention and treatment approaches were reviewed. Conclusion: There is inadequate evidence to strongly support the use of a particular strategy to reduce radiation-induced intestinal damage. More high-quality randomized controlled trials are required for interventions with limited evidence suggestive of potential benefits.

Platelet-rich plasma improves the therapeutic efficacy of mesenchymal stem cells by enhancing their secretion of angiogenic factors in a combined radiation and wound injury model

Delayed wound healing after radiation exposure can cause serious cutaneous damage, and its treatment is a major clinical challenge. Although mesenchymal stem cells (MSCs) have emerged as a promising therapeutic agent in regenerative medicine, they alone do not produce satisfactory effects in a combined radiation and wound injury (CRWI) model. Here, we investigated the therapeutic effect of combined umbilical cord blood-derived (UCB)-MSCs and platelet-rich plasma (PRP) treatment on wound healing in a CRWI mouse model. First, we assessed the release of cytokines from UCB-MSCs cultured with PRP and observed changes in the expression of angiogenic factors. The angiogenic paracrine factors from UCB-MSCs cultured with PRP were assessed in human umbilical vein endothelial cells (HUVECs). To assess therapeutic efficacy, UCB-MSCs and PRP were topically implanted into a CRWT mouse model. Vascular endothelial growth factor (VEGF), a pro-angiogenic growth factor, urokinase-type plasminogen activator and contributor to VEGF-induced signalling were more highly expressed in conditioned media of UCB-MSCs cultured with PRP than in that of UCB-MSCs alone. Furthermore, conditioned media of UCB-MSCs cultured with PRP increased the formation of tube-like structures in HUVECs. Co-treatment of UCB-MSCs and PRP in a CRWI mouse model increased the wound closure rate and angiogenesis compared with an untreated irradiated group. Moreover, increased expression of VEGF and CD31 were observed in the wound tissue of co-treated mice compared with untreated irradiated mice. PRP stimulates the release of angiogenic factors from UCB-MSCs, and combined therapy of UCB-MSCs and PRP improves regeneration efficacy by enhancing angiogenesis in a CRWI model.

Transplantation of stem cells from umbilical cord blood as therapy for type I diabetes

In recent years, human umbilical cord blood has emerged as a rich source of stem, stromal and immune cells for cell-based therapy. Among the stem cells from umbilical cord blood, CD45+ multipotent stem cells and CD90+ mesenchymal stem cells have the potential to treat type I diabetes mellitus (T1DM), to correct autoimmune dysfunction and replenish β-cell numbers and function. In this review, we compare the general characteristics of umbilical cord blood-derived multipotent stem cells (UCB-SCs) and umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) and introduce their applications in T1DM. Although there are some differences in surface marker expression between UCB-SCs and UCB-MSCs, the two cell types display similar functions such as suppressing function of stimulated lymphocytes and imparting differentiation potential to insulin-producing cells (IPCs) in the setting of low immunogenicity, thereby providing a promising and safe approach for T1DM therapy.

Therapeutic angiogenesis using stem cell-derived extracellular vesicles: an emerging approach for treatment of ischemic diseases

Ischemic diseases, which are caused by a reduction of blood supply that results in reduced oxygen transfer and nutrient uptake, are becoming the leading cause of disabilities and deaths. Therapeutic angiogenesis is key for the treatment of these diseases. Stem cells have been used in animal models and clinical trials to treat various ischemic diseases. Recently, the efficacy of stem cell therapy has increasingly been attributed to exocrine functions, particularly extracellular vesicles. Extracellular vesicles are thought to act as intercellular communication vehicles to transport informational molecules including proteins, mRNA, microRNAs, DNA fragments, and lipids. Studies have demonstrated that extracellular vesicles promote angiogenesis in cellular experiments and animal models. Herein, recent reports on the use of extracellular vesicles for therapeutic angiogenesis during ischemic diseases are presented and discussed. We believe that extracellular vesicles-based therapeutics will be an ideal treatment method for patients with ischemic diseases.

Analysis of Circular RNA Expression Profile in HEK 293T Cells Exposed to Ionizing Radiation

Radiation therapy is one of the most common cancer treatments. It is important to understand how cells respond to ionizing radiation (IR) to improve therapeutic efficacy. Circular RNAs (circRNAs) recently have been found to regulate a variety of cellular processes. However, it is poorly defined that their expression pattern and their identity in cells following IR exposure. Here, we performed high-throughput sequencing and comprehensive analysis of circRNA expression in human embryonic kidney (HEK) 293T cells before and after irradiation. We identified totally 5592 circRNAs and discovered 1038 new circRNAs. We found 158 circRNAs with significantly differential expression after IR exposure. Among them, there were 61 upregulated and 97 downregulated circRNAs. Using Gene Ontology, Kyoto Encyclopedia of Genes and Genomes pathway, and circRNA-microRNA-messenger RNA network analyses, we found the differentially expressed circRNAs might be involved in the signal pathways of oxidative phosphorylation, epithelial growth factor receptor (EGFR) tyrosine kinase inhibitor resistance, and mammalian target of rapamycin (mTOR) signaling.

Comprehensive circular RNA expression profile in radiation-treated HeLa cells and analysis of radioresistance-related circRNAs

Background

Cervical cancer is one of the most common cancers in women worldwide. Malignant tumors develop resistance mechanisms and are less sensitive to or do not respond to irradiation. With the development of high-throughput sequencing technologies, circular RNA (circRNA) has been identified in an increasing number of diseases, especially cancers. It has been reported that circRNA can compete with microRNAs (miRNAs) to change the stability or translation of target RNAs, thus regulating gene expression at the transcriptional level. However, the role of circRNAs in cervical cancer and the radioresistance mechanisms of HeLa cells are unknown. The objective of this study is to investigate the role of circRNAs in radioresistance in HeLa cells.

Methods

High-throughput sequencing and bioinformatics analysis of irradiated and sham-irradiated HeLa cells. The reliability of high-throughput RNA sequencing was validated using quantitative real-time polymerase chain reaction. The most significant circRNA functions and pathways were selected by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. A circRNA–miRNA–target gene interaction network was used to find circRNAs associated with radioresistance. Moreover, a protein–protein interaction network was constructed to identify radioresistance-related hub proteins.

Results

High-throughput sequencing allowed the identification of 16,893 circRNAs involved in the response of HeLa cells to radiation. Compared with the control group, there were 153 differentially expressed circRNAs, of which 76 were up-regulated and 77 were down-regulated. GO covered three domains: biological process (BP), cellular component (CC) and molecular function (MF). The terms assigned to the BP domain were peptidyl-tyrosine dephosphorylation and regulation of cell migration. The identified CC terms were cell–cell adherens junction, nucleoplasm and cytosol, and the identified MF terms were protein binding and protein tyrosine phosphatase activity. The top five KEGG pathways were MAPK signaling pathway, endocytosis, axon guidance, neurotrophin signaling pathway, and SNARE interactions in vesicular transport. The protein–protein interaction analysis indicated that 19 proteins might be hub proteins.

Conclusions

CircRNAs may play a major role in the response to radiation. These findings may improve our understanding of the role of circRNAs in radioresistance in HeLa cells and allow the development of novel therapeutic approaches.