Mesenchymal Stem Cell-Derived Exosomes Loaded with miR-155 Inhibitor Ameliorate Diabetic Wound Healing

Preclinical and Clinical Studies on the Use of Extracellular Vesicles Derived from Mesenchymal Stem Cells in the Treatment of Chronic Wounds

To date, the widespread implementation of therapeutic strategies for the treatment of chronic wounds, including debridement, infection control, and the use of grafts and various dressings, has been time-consuming and accompanied by many challenges, with definite success not yet achieved. Extensive studies on mesenchymal stem cells (MSCs) have led to suggestions for their use in treating various diseases. Given the existing barriers to utilizing such cells and numerous pieces of evidence indicating the crucial role of the paracrine signaling system in treatments involving MSCs, extracellular vesicles (EVs) derived from these cells have garnered significant attention in treating chronic wounds in recent years. This review begins with a general overview of current methods for chronic wound treatment, followed by an exploration of EV structure, biogenesis, extraction methods, and characterization. Subsequently, utilizing databases such as Google Scholar, PubMed, and ScienceDirect, we have explored the latest findings regarding the role of EVs in the healing of chronic wounds, particularly diabetic and burn wounds. In this context, the role and mode of action of these nanoparticles in healing chronic wounds through mechanisms such as oxygen level elevation, oxidative stress damage reduction, angiogenesis promotion, macrophage polarization assistance, etc., as well as the use of EVs as carriers for engineered nucleic acids, have been investigated. The upcoming challenges in translating EV-based treatments for healing chronic wounds, along with possible approaches to address these challenges, are discussed. Additionally, clinical trial studies in this field are also covered.

Stem Cell-Derived Extracellular Vesicles: Promising Therapeutic Opportunities for Diabetic Wound Healing

Wound healing is a sophisticated and orderly process of cellular interactions in which the body restores tissue architecture and functionality following injury. Healing of chronic diabetic wounds is difficult due to impaired blood circulation, a reduced immune response, and disrupted cellular repair mechanisms, which are often associated with diabetes. Stem cell-derived extracellular vesicles (SC-EVs) hold the regenerative potential, encapsulating a diverse cargo of proteins, RNAs, and cytokines, presenting a safe, bioactivity, and less ethical issues than other treatments. SC-EVs orchestrate multiple regenerative processes by modulating cellular communication, increasing angiogenesis, and promoting the recruitment and differentiation of progenitor cells, thereby potentiating the reparative milieu for diabetic wound healing. Therefore, this review investigated the effects and mechanisms of EVs from various stem cells in diabetic wound healing, as well as their limitations and challenges. Continued exploration of SC-EVs has the potential to revolutionize diabetic wound care.

Biological scaffold as potential platforms for stem cells: Current development and applications in wound healing

Wound repair is a complex challenge for both clinical practitioners and researchers. Conventional approaches for wound repair have several limitations. Stem cell-based therapy has emerged as a novel strategy to address this issue, exhibiting significant potential for enhancing wound healing rates, improving wound quality, and promoting skin regeneration. However, the use of stem cells in skin regeneration presents several challenges. Recently, stem cells and biomaterials have been identified as crucial components of the wound-healing process. Combination therapy involving the development of biocompatible scaffolds, accompanying cells, multiple biological factors, and structures resembling the natural extracellular matrix (ECM) has gained considerable attention. Biological scaffolds encompass a range of biomaterials that serve as platforms for seeding stem cells, providing them with an environment conducive to growth, similar to that of the ECM. These scaffolds facilitate the delivery and application of stem cells for tissue regeneration and wound healing. This article provides a comprehensive review of the current developments and applications of biological scaffolds for stem cells in wound healing, emphasizing their capacity to facilitate stem cell adhesion, proliferation, differentiation, and paracrine functions. Additionally, we identify the pivotal characteristics of the scaffolds that contribute to enhanced cellular activity.

The Immunomodulatory effect of exosomes in diabetes: a novel and attractive therapeutic tool in diabetes therapy

Exosomes carry proteins, metabolites, nucleic acids and lipids from their parent cell of origin. They are derived from cells through exocytosis, are ingested by target cells, and can transfer biological signals between local or distant cells. Therefore, exosomes are often modified in reaction to pathological processes, including infection, cancer, cardiovascular diseases and in response to metabolic perturbations such as obesity and diabetes, all of which involve a significant inflammatory aspect. Here, we discuss how immune cell-derived exosomes origin from neutrophils, T lymphocytes, macrophages impact on the immune reprogramming of diabetes and the associated complications. Besides, exosomes derived from stem cells and their immunomodulatory properties and anti-inflammation effect in diabetes are also reviewed. Moreover, As an important addition to previous reviews, we describes promising directions involving engineered exosomes as well as current challenges of clinical applications in diabetic therapy. Further research on exosomes will explore their potential in translational medicine and provide new avenues for the development of effective clinical diagnostics and therapeutic strategies for immunoregulation of diabetes.

Exosome-coated oxygen nanobubble-laden hydrogel augments intracellular delivery of exosomes for enhanced wound healing

Wound healing is an obvious clinical concern that can be hindered by inadequate angiogenesis, inflammation, and chronic hypoxia. While exosomes derived from adipose tissue-derived stem cells have shown promise in accelerating healing by carrying therapeutic growth factors and microRNAs, intracellular cargo delivery is compromised in hypoxic tissues due to activated hypoxia-induced endocytic recycling. To address this challenge, we have developed a strategy to coat oxygen nanobubbles with exosomes and incorporate them into a polyvinyl alcohol/gelatin hybrid hydrogel. This approach not only alleviates wound hypoxia but also offers an efficient means of delivering exosome-coated nanoparticles in hypoxic conditions. The self-healing properties of the hydrogel, along with its component, gelatin, aids in hemostasis, while its crosslinking bonds facilitate hydrogen peroxide decomposition, to ameliorate wound inflammation. Here, we show the potential of this multifunctional hydrogel for enhanced healing, promoting angiogenesis, facilitating exosome delivery, mitigating hypoxia, and inhibiting inflammation in a male rat full-thickness wound model.

Extracellular vesicles secreted by bone marrow stem cells mediate angiogenesis for the treatment of diabetic ulcers: A systematic review and meta-analysis of preclinical studies

Background

Diabetic ulcers (DUs) typically occur in patients with vascular diseases and diabetes. Extracellular vesicles secreted by bone marrow-derived stem cells (BMSC-EVs) represent a cell-free therapy that has emerged as a promising alternative for treating DU, especially due to significant advancements in the understanding of their role in promoting angiogenesis; however, their application in DU treatment remains in the preclinical stage, and their effectiveness is still uncertain. Therefore, we conducted this meta-analysis to evaluate the therapeutic efficacy of BMSC-EVs in treating DU and to expedite the clinical translation of BMSC-EV therapy for DU.

Methods

We conducted a comprehensive search of PubMed, Cochrane Library, MEDLINE, EMBASE, China National Knowledge Infrastructure (CNKI), Wanfang Database, VIP Database, and our self-constructed database of Chinese Biomedical Literature up to May 2023 to identify preclinical studies related to the therapeutic use of extracellular vesicles secreted by bone marrow-derived stem cells for treating diabetic ulcers. Outcome measures included wound healing rate, neovascularization density, a-sma, and CD31. RevMan 5 software was employed for all statistical analyses.

Results

In this meta-analysis, a total of 11 studies involving 103 animals were identified. The pooled analysis indicated that BMSC-EV treatment showed a superior wound healing rate compared to that of the control group (SMD = 1.06, 95% CI [0.52, 1.60], P = 0.0001). In the subgroup analysis, EV combined with new materials or drug therapy performed better than the sole injection of extracellular vesicles (SMD = 1.85, 95% CI [0.87, 2.82], P < 0.00001). BMSC-EV treatment also resulted in a higher number of neovascular structures compared to the control group(SMD = 5.80, 95% CI[0.89,10.71], P = 0.006). In the subgroup analysis, EV combined therapy showed a significant difference in the number of blood vessels compared to the sole injection of extracellular vesicles (SMD = 4.90, 95% CI[2.64,7.15], P < 0.00001). However, BMSCs-EV treatment did not demonstrate any statistically significant difference in the angiogenesis-related indicators CD31 and α-SMA compared to the control group (SMD = 1.61, 95% CI[-0.51,3.74], P = 0.14).

Conclusion

According to the current meta-analysis, BMSC-EV therapy can enhance the healing of diabetic ulcers and promote wound angiogenesis, particularly when used in combination with novel dressings or other drugs, which further accelerates the healing process of diabetic ulcers. To establish the most effective parameters for EV treatment in diabetic ulcers, future research should promptly progress into clinical trials.

Development and biological evaluation of smart powder bandage for wound healing and dressing applications

Cutaneous wounds are one of the pressing concerns for healthcare systems globally. With large amounts of water, conventional hydrogels encounter obstacles in effectively delivering small molecules and peptides for wound healing. The surplus water content challenges the stability and sustained release of small molecules and peptides, diminishing their therapeutic efficacy. Our pioneering smart powder bandage, fabricated through freeze-drying, ensures a water content of <1 % during storage. Upon contact with wound exudate, it forms hydrogel layers, thereby optimizing the delivery of peptides. Tailored for thermosensitive peptides such as EGF, this strategy surmounts the limitations of conventional hydrogels, providing a robust platform for efficacious therapeutic delivery in wound healing applications. Developing multifunctional wound dressings with antibacterial, anti-inflammatory, hemostatic, and healing properties is essential to promote wound healing. Therefore, the current investigation reports the development of multifunctional EGF@Silnanom SPB with the above-mentioned properties to promote wound healing using silver nanomix (Silnanom) and bioactive epidermal growth factors (EGF) as active therapeutics. The characterization of smart powder bandage (SPB) revealed that Silnanom were homogeneously dispersed in the entangled polymer network. The multifunctional smart powder bandage exhibited high bacterial inhibition rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and rigorous hemocompatibility, cell compatibility, and in vivo studies also confirmed its biocompatibility. Furthermore, multifunctional EGF@Silnanom SPB effectively reduced pro-inflammatory markers, enhanced collagen deposition, promoted angiogenesis, and accelerated wound healing in a full-thickness mouse wound model through the sustained release of Silnanom and EGF. Additionally, the results of hemostasis analysis on the tail amputation mouse model confirmed the hemostasis properties of the EGF@Silnanom SPB. Overall, the multifunctional EGF@Silnanom SPB shows promising potential for skin wound repair, offering a potent and effective solution to the challenges posed by conventional wound dressings.

IFN-γ enhances the therapeutic efficacy of MSCs-derived exosome via miR-126-3p in diabetic wound healing by targeting SPRED1

BACKGROUND AND AIMS

The traditional treatment of diabetic wounds is unsatisfactory. Exosomes isolated from bone marrow mesenchymal stem cells (BMSCs) promote the healing of diabetic wounds. However, whether the exosomes secreted by interferon (IFN)-γ-pretreated BMSCs have an enhanced therapeutic effect on diabetic wound healing and the relevant mechanisms remain unclear.

METHODS

In this study, we isolated exosomes from the corresponding supernatants of BMSCs with (IExos) or without IFN-γ treatment (NExos). Human umbilical vein endothelial cells (HUVECs) were used to investigate the proliferation, migration, and tube formation under different treatments in vitro. Diabetic mice were induced by intraperitoneal administration of streptozotocin, and a circular full-thickness dermal defect was then made on the back of each mouse, followed by a multisite subcutaneous injection of phosphate buffered saline or exosomes. Hematoxylin-eosin (H&E) staining, Masson's trichrome staining, and histological analysis were performed to assess the speed and quality of wound healing.

RESULTS

NExos treatment accelerated the healing of diabetic wounds by promoting angiogenesis in vivo and in vitro, and IExos exhibited superior therapeutic efficiency. MicroRNA (miR)-126-3p was significantly increased in IExos, and exosomal miR-126-3p promoted angiogenesis and diabetic wound healing via its transfer to HUVECs. miR-126-3p regulates SPRED1 by directly targeting the 3'-UTR. Mechanistically, IFN-γ-pretreated BMSCs secreted miR-126-3p-enriched exosomes, which enhanced the function of HUVECs and promoted angiogenesis via the SPRED1/Ras/Erk pathway.

CONCLUSION

Exosomal miR-126-3p secreted from IFN-γ-pretreated BMSCs exhibited higher therapeutic efficacy than NExos in diabetic wound healing by promoting angiogenesis via the SPRED1/Ras/Erk axis.

Effect and mechanism of microRNAs on various diabetic wound local cells

The difficulty of wound healing in diabetes mellitus has long been regarded as a thorny problem in the medical field. One of the important reasons is the abnormal function of wound-related cells. A large number of recent studies have shown that microRNA (miR), a noncoding RNA that exists in eukaryotic cells, is closely linked to the functions of various cells in diabetic wound, and ultimately affects the healing of wound. This paper establishes for the first time the connection between miR and wound healing from the cellular perspective and summarizes the effects of various miRs on one or more kinds of wound cells, including their targets and related mechanisms. The abnormal expression of miRs in the wound has certain value for the early diagnosis of diabetic wounds. Moreover, it seems that correcting miRs that are abnormal expressed in the wound or artificially adding miRs that can promote wound healing has an essential therapeutic value.

Extracellular Vesicles: Emergent and Multiple Sources in Wound Healing Treatment

Non-healing wound- and tissue-injury are commonly experienced worldwide by the aging population. The persistence of disease commonly leads to tissue infection, resulting in severe clinical complications. In the last decade, extracellular vesicles (EVs) have been considered promising and emergent therapeutic tools to improve the healing processes. Therefore, efforts have been directed to develop a cell-free therapeutic platform based on EV administration to orchestrate tissue repair. EVs derived from different cell types, including fibroblast, epithelial, and immune cells are recruited to the injured sites and in turn take part in scar formation. EVs are nano-sized particles containing a heterogeneous cargo consisting of lipids, proteins, and nucleic acids protected from degradation by their lipid bilayer. Noteworthy, since EVs have natural biocompatibility and low immunogenicity, they represent the ideal therapeutic candidates for regenerative purposes. Indeed, EVs are released by several cell types, and even if they possess unique biological properties, their functional capability can be further improved by engineering their content and functionalizing their surface, allowing a specific cell cargo delivery. Herein, we provide an overview of preclinical data supporting the contribution of EVs in the repair and regenerative processes, focusing on different naïve EV sources, as well as on their engineering, to offer a scalable and low-cost therapeutic option for tissue repair.

Engineering Cell-Derived Nanovesicles for Targeted Immunomodulation

Extracellular vesicles (EVs) show promise for targeted drug delivery but face production challenges with low yields. Cell-derived nanovesicles (CDNVs) made by reconstituting cell membranes could serve as EV substitutes. In this study, CDNVs were generated from mesenchymal stem cells by extrusion. Their proteomic composition, in vitro and in vivo toxicity, and capacity for loading RNA or proteins were assessed. Compared with EVs, CDNVs were produced at higher yields, were comprised of a broader range of proteins, and showed no detrimental effects on cell proliferation, DNA damage, or nitric oxide production in vitro or on developmental toxicity in vivo. CDNVs could be efficiently loaded with RNA and engineered to modify surface proteins. The feasibility of generating immunomodulatory CDNVs was demonstrated by preparing CDNVs with enhanced surface expression of PD1, which could bind to PD-L1 expressing tumor cells, enhance NK and T cell degranulation, and increase immune-mediated tumor cell death. These findings demonstrate the adaptability and therapeutic promise of CDNVs as promising substitutes for natural EVs that can be engineered to enhance immunomodulation.

A Combined Experimental and Computational Study of Novel Benzotriazinone Carboxamides as Alpha-Glucosidase Inhibitors

Diabetes is a chronic metabolic disorder of the endocrine system characterized by persistent hyperglycemia appears due to the deficiency or ineffective use of insulin. The glucose level of diabetic patients increases after every meal and medically recommended drugs are used to control hyperglycemia. Alpha-glucosidase inhibitors are used as antidiabetic medicine to delay the hydrolysis of complex carbohydrates. Acarbose, miglitol, and voglibose are commercial drugs but patients suffer side effects of flatulence, bloating, diarrhea, and loss of hunger. To explore a new antidiabetic drug, a series of benzotriazinone carboxamides was synthesized and their alpha-glucosidase inhibition potentials were measured using in vitro experiments. The compounds 14k and 14l were found to be strong inhibitors compared to the standard drug acarbose with IC50 values of 27.13 ± 0.12 and 32.14 ± 0.11 μM, respectively. In silico study of 14k and 14l was carried out using molecular docking to identify the type of interactions developed between these compounds and enzyme sites. Both potent compounds 14k and 14l exhibited effective docking scores by making their interactions with selected amino acid residues. Chemical hardness and orbital energy gap values were investigated using DFT studies and results depicted affinity of 14k and 14l towards biological molecules. All computational findings were found to be in good agreement with in vitro results.

Exosomes: A Promising Strategy for Repair, Regeneration and Treatment of Skin Disorders

The skin is the organ that serves as the outermost layer of protection against injury, pathogens, and homeostasis with external factors; in turn, it can be damaged by factors such as burns, trauma, exposure to ultraviolet light (UV), infrared radiation (IR), activating signaling pathways such as Toll-like receptors (TLR) and Nuclear factor erythroid 2-related factor 2 (NRF2), among others, causing a need to subsequently repair and regenerate the skin. However, pathologies such as diabetes lengthen the inflammatory stage, complicating the healing process and, in some cases, completely inhibiting it, generating susceptibility to infections. Exosomes are nano-sized extracellular vesicles that can be isolated and purified from different sources such as blood, urine, breast milk, saliva, urine, umbilical cord bile cells, and mesenchymal stem cells. They have bioactive compounds that, thanks to their paracrine activity, have proven to be effective as anti-inflammatory agents, inducers of macrophage polarization and accelerators of skin repair and regeneration, reducing the possible complications relating to poor wound repair, and prolonged inflammation. This review provides information on the use of exosomes as a promising therapy against damage from UV light, infrared radiation, burns, and skin disorders.

The potential application of encapsulated exosomes: A new approach to increase exosomes therapeutic efficacy

Cell therapy is one of the methods that have shown promising results in treating diseases in recent decades. However, the use of different types of cells comes with limitations. The application of immune cells in cell therapy can lead to cytokine storms and inappropriate responses to self-antigens. Also, the use of stem cells has the potential to create tumors. Also, cells may not migrate to the injury site after intravenous injection. Therefore, using exosomes from different cells as therapeutic candidates were proposed. Due to their small size and favorable characteristics, such as biocompatibility and immunocompatibility, the easy storage and isolation, exosomes have attracted much attention. They are used in treating many diseases, including cardiovascular diseases, orthopedic diseases, autoimmune diseases, and cancer. However, the results of various studies have shown that the therapeutic efficiency of exosomes (Exo) can be increased by loading different drugs and microRNAs inside them (encapsulated exosomes). Therefore, analyzing studies investigating encapsulated exosomes' therapeutic ability is critical. In this study, we have examined the studies related to the use of encapsulated exosomes in treating diseases such as cancer and infectious diseases and their use in regenerative medicine. Compared to intact exosomes, the results show that the application of encapsulated exosomes has a higher therapeutic ability. Therefore it is suggested to use this method depending on the treatment type to increase the treatment's efficiency.

Mesenchymal Stem Cell Derived Exosomes Therapy in Diabetic Wound Repair

Nowadays, refractory diabetic wounds cause a worldwide medical burden. Mesenchymal stem cells derived exosomes (MSC-Exos) show promise as a solid alternative to existing therapeutics in the latest researches, since MSC-Exos share similar biologic activity but less immunogenicity when compared with MSCs. To facilitate further understanding and application, it is essential to summarize the current progress and limitations of MSC-Exos in the treatment of diabetic wounds. In this review, we introduce the effects of different MSC-Exos on diabetic wounds according to their origins and contents and discuss the specific experimental conditions, target wound cells/pathways, and specific mechanisms. In addition, this paper focuses on the combination of MSC-Exos and biomaterials, which improves the efficacy and utilization of MSC-Exos therapy. Together, exosome therapy has high clinical value and application prospects, both in its role and in combination with biomaterials, while novel drugs or molecules loaded into exosomes as carriers targeting wound cells will be development trends.

Bioengineered exosomal-membrane-camouflaged abiotic nanocarriers: neurodegenerative diseases, tissue engineering and regenerative medicine

A bio-inspired strategy has recently been developed for camouflaging nanocarriers with biomembranes, such as natural cell membranes or subcellular structure-derived membranes. This strategy endows cloaked nanomaterials with improved interfacial properties, superior cell targeting, immune evasion potential, and prolonged duration of systemic circulation. Here, we summarize recent advances in the production and application of exosomal membrane-coated nanomaterials. The structure, properties, and manner in which exosomes communicate with cells are first reviewed. This is followed by a discussion of the types of exosomes and their fabrication methods. We then discuss the applications of biomimetic exosomes and membrane-cloaked nanocarriers in tissue engineering, regenerative medicine, imaging, and the treatment of neurodegenerative diseases. Finally, we appraise the current challenges associated with the clinical translation of biomimetic exosomal membrane-surface-engineered nanovehicles and evaluate the future of this technology.

Stem cell-derived exosomes: emerging therapeutic opportunities for wound healing

Wound healing is a dynamic and highly sequential process involving a series of overlapping spatial and temporal phases, including hemostasis, inflammation, proliferation, and tissue remodeling. Mesenchymal stem cells (MSCs) are multipotent stem cells with self-renewal, multidirectional differentiation potential, and paracrine regulation. Exosomes are subcellular vesicular components 30-150 nm in size and are novel carriers of intercellular communication in regulating the biological behaviors of skin cells. Compared to MSCs, MSC-derived exosomes (MSC-exos) possess lower immunogenicity, easy storage, and highly effective biological activity. MSC-exos, mainly derived from adipose-derived stem cells (ADSCs), bone marrow-derived MSCs (BMSCs), human umbilical cord MSCs (hUC-MSCs), and other stem cell types, play a role in shaping the activity of fibroblasts, keratinocytes, immune cells, and endothelial cells in diabetic wounds, inflammatory wound repair, and even wound-related keloid formation. Therefore, this study focuses on the specific roles and mechanisms of different MSC-exos in wound healing, as well as the current limitations and various perspectives. Deciphering the biological properties of MSC-exos is crucial to providing a promising cell-free therapeutic tool for wound healing and cutaneous regeneration.

Research progress of exosomes as drug carriers in cancer and inflammation

Extracellular vesicles (EVs) could be produced by most cells and play an important role in disease development. As a subtype of EVs, exosomes exhibit suitable size, rich surface markers and diverse contents, making them more appealing as potential drug carriers. Compared with traditional synthetic nanoparticles, exosomes possess superior biocompatibility and much lower immunogenicity. This work reviewed the most up-to-date research progress of exosomes as carriers for nucleic acids, proteins and small molecule drugs for cancer and inflammation management. The drug loading strategies and potential cellular uptake behaviour of exosomes are highlighted, trying to provide reference for future exosome design and application.

Engineering exosome-based biomimetic nanovehicles for wound healing

Complexity and difficulties in wound management are pressing concerns that affect patients' quality of life and may result in tissue infection, necrosis, and loss of local and systemic functions. Hence, novel approaches to accelerate wound healing are being actively explored over the last decade. Exosomes as important mediators of intercellular communications are promising natural nanocarriers due to their biocompatibility, low immunogenicity, drug loading and targeting capacities, and innate stability. More importantly, exosomes are developed as a versatile pharmaceutical engineering platform for wound repair. This review provides an overview of the biological and physiological functions of exosomes derived from a variety of biological origins during wound healing phases, strategies for exosomal engineering, and therapeutic applications in skin regeneration.

The effectiveness of cell-derived exosome therapy for diabetic wound: A systematic review and meta-analysis

BACKGROUND

The prevalence of diabetes among the elderly population is significant and rising annually. One of the most severe and frequent complications of diabetes mellitus is the diabetic wound, which has long-term negative effects on patients' finances, mental health, and functional abilities. Exosomes, a cell-free therapy, have emerged as a promising novel treatment for diabetic wounds, but their mechanism is still not entirely understood. Therefore, we conducted this meta-analysis to assess the effectiveness of exosomes in the management of diabetic wounds.

METHODS

We searched PubMed, the Cochrane Library, EMBASE, and Web of Science for pertinent studies that described the therapeutic benefits of exosomes on diabetic wound models that were released before October 17, 2022. The outcome indicators consisted of wound healing rate, neovascular density, re-epithelialization rate, collagen deposition, scar width, and inflammatory factors. RevMan 5.4 software was used to conduct all statistical analyses.

RESULTS

A total of 21 studies with 323 animals were identified in this meta-analysis. Pooled analyses demonstrated that exosome therapy was shown to be superior to control therapy in terms of wound healing rate (SMD = 5.42; 95 %CI = 4.40-6.44; P < 0.00001), neovascular density (SMD = 5.48; 95 %CI = 4.31-6.64; P < 0.00001), re-epithelialization rate (SMD = 5.06; 95 %CI = 3.75-6.37; P < 0.00001), collagen deposition (SMD = 4.78; 95 %CI = 3.58-5.98; P < 0.00001), scar width (SMD = -8.10; 95 %CI = -10.31 to -5.89; P < 0.00001). Additionally, the expression of inflammatory factors was significantly downregulated in the exosome treatment group.

CONCLUSIONS

According to this meta-analysis of the current trials, exosome therapy can enhance the quality of diabetic wounds, especially when used in conjunction with novel dressings. To demonstrate the most efficient exosomes and therapeutic parameters for the treatment of diabetic wounds, future studies should conduct sizable, randomized, double-blind trials with high-quality, long-term follow-ups.

Mesenchymal Stem Cell Derived Extracellular Vesicles: Promising Nanomedicine for Cutaneous Wound Treatment

A skin wound represents a rupture caused by external damage or the existence of underlying pathological conditions. Sometimes, skin wound healing processes may place a heavy burden on patients, families, and society. Wound healing processes mainly consist of several continuous, dynamic, but overlapping stages, namely, the coagulation stage, inflammation stage, proliferation stage, and remodeling stage. Bacterial infection, excessive inflammation, impaired angiogenesis, and scar formation constitute the four significant factors impeding the recovery efficacy of skin wounds. This encourages scientists to develop multifunctional nanomedicines to meet challenging needs. As we know, mesenchymal stem cells (MSCs) have been widely explored for wound repair owing to their unique capability for self-renewal and multipotency. However, problems including immune concerns and legal restrictions should be properly resolved before MSC-based therapeutics are safely and widely used in clinics. Besides, maintaining the high viability/proliferation capability of MSCs during administration processes and therapy procedures is also one of the biggest technical bottlenecks. Extracellular vesicles (EVs) are cell-derived nanovesicles, that not only possess the basic characteristics and functions of their corresponding maternal cells but also contain several outstanding advantages including abundant sources, excellent biocompatibility, and convenient administration routes. Furthermore, the membrane surface and cavity are easy to flexibly modify to meet versatile application needs. Recently, MSC-derived EVs have emerged as promising therapeutics for skin wound repair. However, current reviews are too broad and rarely focused on the specific roles of EVs in the different stages of wound recovery. Therefore, it is quite necessary to demonstrate the significance of stem cell-derived EVs in promoting wound healing from several specific aspects. Here, this review primarily tries to provide critical comments on current advances in EVs derived from MSCs for wound repair, particularly elaborating on their impressive roles in effectively eliminating infections, inhibiting inflammation, promoting angiogenesis, and reducing scar formation. Last but not least, current limitations and future prospects of EVs derived from MSCs in the areas of wound repair are also objectively analyzed.

Loading Nanoceria Improves Extracellular Vesicle Membrane Integrity and Therapy to Wounds in Aged Mice

Wound healing is a programmed process through which tissue restores its integrity after an injury. Advancing age is a risk factor for delayed cutaneous wound healing; however, ideal therapeutic approaches for aged wound have not been developed yet. By dissecting the harsh microenvironment of aged wound, we propose an integrated chemical and biological strategy to mitigate two main hostile factors including oxidative stress and ischemia. Mesenchymal stem cell-derived extracellular vesicles (EVs) are a rising star in regenerative medicine due to their powerful facilitation in tissue repair and regeneration. However, the fragile lipid membrane limits their function under the oxidative stress microenvironment. Nanoceria is an antioxidative nanozyme; here, we reveal that nanoceria-loaded EVs derived from mesenchymal stem cells facilitate cutaneous wound healing in aged mice. DG-CeO₂ was prepared via coating CeO₂ covalently with d-glucose to promote their cellular endocytosis. DG-CeO₂ was packaged into EVs under optimized hypoxic conditions (DG-CeO₂ EVs^Hyp). We further demonstrated that DG-CeO₂ EVs^Hyp had favorable biocompatibility and antioxidative and proangiogenic effects during the cutaneous wound healing in both young and aged mice. Further evidence revealed that DG-CeO₂ EVs^Hyp-transferred miR-92a-3p/125b-5p and their targets associated with aging degeneration may be the potential mechanisms. Collectively, these findings highlight that nanoceria-loaded EVs released by engineered stem cells may represent a potential therapeutic approach for tissue regeneration in aged population.

Extracellular vesicle‑mediated miR‑126‑3p transfer contributes to inter‑cellular communication in the liver tumor microenvironment

Extracellular vesicles (EVs) and their contents are gaining recognition as important mediators of intercellular communication through the transfer of bioactive molecules, such as non‑coding RNA. The present study comprehensively assessed the microRNA (miRNA/miR) content within EVs released from HepG2 liver cancer (LC) cells and LX2 hepatic stellate cells (HSCs) and determined the contribution of EV miRNA to intercellular communication. Using both transwell and spheroid co‑cultures of LC cells and HSCs, miR‑126‑3p within EV was established as a mediator of HSC to LC cell communication that influenced tumor cell migration and invasion, as well as the growth of multicellular LC/HSC spheroids. Manipulation of miR‑126‑3p either by enforced expression using pre‑miR‑126‑3p or by inhibition using antimiR‑126‑3p did not alter tumor cell viability, proliferation or sensitivity to either sorafenib or regorafenib. By contrast, enforced expression of miR‑126‑3p decreased tumor‑cell migration. Knockdown of miR‑126‑3p in tumor cells increased disintegrin and metalloproteinase domain‑containing protein 9 (ADAM9) expression and in HSCs increased collagen‑1A1 accumulation with an increase in compactness of multicellular spheroids. Within LC/HSC spheroids, ADAM9 and vascular endothelial growth factor expression was increased by silencing of miR‑126‑3p but diminished with the restoration of miR‑126‑3p. These studies implicate miR‑126‑3p in functional effects on migration, invasion and spheroid growth of tumor cells in the presence of HSCs, and thereby demonstrate functional EV‑RNA‑based intercellular signaling between HSCs and LC cells that is directly relevant to tumor‑cell behavior.

Future applications of exosomes delivering resolvins and cytokines in facilitating diabetic foot ulcer healing

Type 2 diabetes mellitus (T2DM) increases the risk of many lethal and debilitating conditions. Among them, foot ulceration due to neuropathy, vascular disease, or trauma affects the quality of life of millions in the United States and around the world. Physiological wound healing is stalled in the inflammatory phase by the chronicity of inflammation without proceeding to the resolution phase. Despite advanced treatment, diabetic foot ulcers (DFUs) are associated with a risk of amputation. Thus, there is a need for novel therapies to address chronic inflammation, decreased angiogenesis, and impaired granulation tissue formation contributing to the non-healing of DFUs. Studies have shown promising results with resolvins (Rv) and anti-inflammatory therapies that resolve inflammation and enhance tissue healing. But many of these studies have encountered difficulty in the delivery of Rv in terms of efficiency, tissue targetability, and immunogenicity. This review summarized the perspective of optimizing the therapeutic application of Rv and cytokines by pairing them with exosomes as a novel strategy for targeted tissue delivery to treat non-healing chronic DFUs. The articles discussing the T2DM disease state, current research on Rv for treating inflammation, the role of Rv in enhancing wound healing, and exosomes as a delivery vehicle were critically reviewed to find support for the proposition of using Rv and exosomes in combination for DFUs therapy. The literature reviewed suggests the beneficial role of Rv and exosomes and exosomes loaded with anti-inflammatory agents as promising therapeutic agents in ulcer healing.

Small extracellular vesicles from mesenchymal stem cells: A potential Weapon for chronic non-healing wound treatment

Chronic non-healing wounds have posed a severe threat to patients mentally and physically. Behavior dysregulation of remaining cells at wound sites is recognized as the chief culprit to destroy healing process and hinders wound healing. Therefore, regulating and restoring normal cellular behavior is the core of chronic non-healing wound treatment. In recent years, the therapy with mesenchymal stem cells (MSCs) has become a promising option for chronic wound healing and the efficacy has increasingly been attributed to their exocrine functions. Small extracellular vesicles derived from MSCs (MSC-sEVs) are reported to benefit almost all stages of wound healing by regulating the cellular behavior to participate in the process of inflammatory response, angiogenesis, re-epithelization, and scarless healing. Here, we describe the characteristics of MSC-sEVs and discuss their therapeutic potential in chronic wound treatment. Additionally, we also provide an overview of the application avenues of MSC-sEVs in wound treatment. Finally, we summarize strategies for large-scale production and engineering of MSC-sEVs. This review may possibly provide meaningful guidance for chronic wound treatment with MSC-sEVs.

How to maximize the therapeutic effect of exosomes on skin wounds in diabetes mellitus: Review and discussion

Chronic skin wound healing, especially in diabetes mellitus, is still unsolved. Although many efforts have been made to treat diabetic skin wounds, current strategies have achieved limited effectiveness. Nowadays, a great number of studies have shown that exosomes might be a promising approach for treating diabetic wounds. Many studies and reviews have focused on investigating and discussing the effectiveness and mechanism of exosomes. However, maximizing its value in treating skin wounds in diabetes mellitus requires further consideration. In this review, we reviewed and discussed the aspects that could be further improved in this process, including finding a better source of exosomes, engineering exosomes, adjusting dosage and frequency, and combining more efficient delivery methods. This review provided an overview and idea of what we can do to improve the therapeutic effect of exosomes on skin wounds in diabetes mellitus. Only by combining all the factors that affect the effectiveness of exosomes in diabetic wound healing can we further promote their clinical usefulness.

Mesenchymal stem cell-derived exosomes: The dawn of diabetic wound healing

Chronic wound healing has long been an unmet medical need in the field of wound repair, with diabetes being one of the major etiologies. Diabetic chronic wounds (DCWs), especially diabetic foot ulcers, are one of the most threatening chronic complications of diabetes. Although the treatment strategies, drugs, and dressings for DCWs have made great progress, they remain ineffective in some patients with refractory wounds. Stem cell-based therapies have achieved specific efficacy in various fields, with mesenchymal stem cells (MSCs) being the most widely used. Although MSCs have achieved good feedback in preclinical studies and clinical trials in the treatment of cutaneous wounds or other situations, the potential safety concerns associated with allogeneic/autologous stem cells and unknown long-term health effects need further attention and supervision. Recent studies have reported that stem cells mainly exert their trauma repair effects through paracrine secretion, and exosomes play an important role in intercellular communication as their main bioactive component. MSC-derived exosomes (MSC-Exos) inherit the powerful inflammation and immune modulation, angiogenesis, cell proliferation and migration promotion, oxidative stress alleviation, collagen remodeling imbalances regulation of their parental cells, and can avoid the potential risks of direct stem cell transplantation to a large extent, thus demonstrating promising performance as novel "cell-free" therapies in chronic wounds. This review aimed to elucidate the potential mechanism and update the progress of MSC-Exos in DCW healing, thereby providing new therapeutic directions for DCWs that are difficult to be cured using conventional therapy.

Non-coding RNAs: Role in diabetic foot and wound healing

Diabetic foot ulcer (DFU) and poor wound healing are chronic complications in patients with diabetes. The increasing incidence of DFU has resulted in huge pressure worldwide. Diagnosing and treating this condition are therefore of great importance to control morbidity and improve prognosis. Finding new markers with potential diagnostic and therapeutic utility in DFU has gathered increasing interest. Wound healing is a process divided into three stages: Inflammation, proliferation, and regeneration. Non-coding RNAs (ncRNAs), which are small protected molecules transcribed from the genome without protein translation function, have emerged as important regulators of diabetes complications. The deregulation of ncRNAs may be linked to accelerated DFU development and delayed wound healing. Moreover, ncRNAs can be used for therapeutic purposes in diabetic wound healing. Herein, we summarize the role of microRNAs, long ncRNAs, and circular RNAs in diverse stages of DFU wound healing and their potential use as novel therapeutic targets.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: A Potential Therapy for Diabetes Mellitus and Diabetic Complications

As a novel cell-free strategy, mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) inherit the therapeutic potential of donor cells, and are widely used for the treatment of many diseases. Increasing studies have shown that MSC-EVs transfer various bioactive molecules to create a beneficial microenvironment, thus exerting protective roles in diabetic mellitus (DM) and diabetic complications. To overcome the limitations of natural MSC-EVs such as heterogeneity and insufficient function, several modification methods have been established for constructing engineered MSC-EVs with elevated repairing efficiency. In this review, the PubMed library was searched from inception to August 2022, using a combination of Medical Subject Headings (MeSH) and keywords related to MSC-EVs, DM, and diabetic complications. We provide an overview of the major characteristics of MSC-EVs and summarize the recent advances of MSC-EV-based therapy for hyperglycemia-induced tissue damage with an emphasis on MSC-EV-mediated delivery of functional components. Moreover, the potential applications of engineered MSC-EVs in DM-related diseases therapy are discussed by presenting examples, and the opportunities and challenges for the clinical translation of MSC-EVs, especially engineered MSC-EVs, are evaluated.

Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Accelerate Diabetic Wound Healing via Promoting M2 Macrophage Polarization, Angiogenesis, and Collagen Deposition

Some scholars have suggested that the clinical application of exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs-exo) might represent a novel strategy to improve diabetic wound healing. However, the mechanisms underlying the effects of hucMSCs-exo on wound healing remain poorly understood. This study aimed to identify the mechanism of hucMSCs-exo in treating diabetic wounds. HucMSCs-exo were isolated from human umbilical cord mesenchymal stem cells (hucMSCs) and subcutaneously injected into full-thickness wounds in diabetic rats. Wound healing closure rates and histological analysis were performed. The levels of tumor necrosis factor-α (TNF-α), macrophage mannose receptor (MMR/CD206), platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31), and vascular endothelial growth factor (VEGF) were detected by immunohistochemistry. The degree of collagen deposition was examined using Masson’s trichrome staining. Gross evaluation of wound healing was carried out from day 0 to 14 post-surgery, and the wound site was harvested for histology on days 3, 7, and 14 post-wounding. HucMSCs-exo transplantation increased diabetic wound healing. In vitro, hucMSCs-exo promoted the proliferation of human umbilical vein endothelial cells (HUVECs) and NIH-3T3 cells. In vivo, hucMSCs-exo reduced wound area and inflammatory infiltration and increased collagen fibers. In addition, wound tissues in the hucMSCs-exo group had higher CD206, CD31, and VEGF expressions and lower TNF-α levels than those in the control group on day 14. Our results demonstrated that hucMSCs-exo facilitated diabetic wound repair by inducing anti-inflammatory macrophages and promoting angiogenesis and collagen deposition.

The role of melatonin in bone regeneration: A review of involved signaling pathways

Increasing bone resorption followed by decreasing bone mineralization are hallmarks of bone degeneration, which mostly occurs in the elderly population and post-menopausal women. The use of mesenchymal stem cells (MSCs) has raised many promises in the field of bone regeneration due to their high osteoblastic differentiation capacity and easy availability from abundant sources. A variety of compounds, including growth factors, cytokines, and other internal factors, have been combined with MSCs to increase their osteoblastic differentiation capacity. One of these factors is melatonin, whose possible regulatory role in bone metabolism and formation has recently been suggested by many studies. Melatonin also is a potential signaling molecule and can affect many of the signaling pathways involved in MSCs osteoblastic differentiation, such as activation of PI3K/AKT, BMP/Smad, MAPK, NFkB, Nrf2/HO-1, Wnt, SIRT/SOD, PERK/ATF4. Furthermore, melatonin in combination with other components such as strontium, vitamin D3, and vitamin K2 has a synergistic effect on bone microstructure and improves bone mineral density (BMD). In this review article, we aim to summarize the regulatory mechanisms of melatonin in osteoblastic differentiation of MSCs and underling involved signaling pathways as well as the clinical potential of using melatonin in bone degenerative disorders.

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.

Exosome-based drug delivery systems and their therapeutic applications

In the past few decades, scientists have actively worked on developing effective drug delivery systems (DDSs) as means to control life-threatening diseases and challenging illnesses.

Increased Expression of miR-155 in Peripheral Blood and Wound Margin Tissue of Type 2 Diabetes Mellitus Patients Associated with Diabetic Foot Ulcer

PURPOSE

To investigate the correlations of miR-155 expression in the peripheral blood and wound margin tissue of patients with diabetic foot ulcer (DFU) and explore the clinical value of miR-155 as a potential biomarker for the diagnosis and treatment outcomes of DFU.

METHODS

Sixty newly diagnosed T2DM patients without DFU (T2DM group), 112 T2DM patients with DFU (DFU group), and 60 healthy controls (NC group) were included. MiR-155 levels in the peripheral blood and wound margin tissue were determined by quantitative real-time PCR, while clinical features and risk factors of DFU were explored. Multiple stepwise logistic regression analysis was used to determine whether miR-155 expression was an independent risk factor for DFU. The diagnostic effectiveness of miR-155 level on DFU was evaluated using ROC curve analysis.

RESULTS

A significant decrease in the expression level of miR-155 was observed in T2DM group compared with NC group (P < 0.05), while a markedly increased miR-155 expression level was noted in DFU group compared with T2DM group (P < 0.01). Moreover, there was a negative correlation between the expression levels of miR-155 with healing rate of DFU. Kaplan-Meier survival curve analysis showed that the cumulative rate of unhealed DFU in miR-155 high expression group is higher than that in miR-155 low expression group, both in peripheral blood and wound margin tissue (log rank, P = 0.004, P < 0.001, respectively). The multivariate logistic regression analysis confirmed that a high expression of miR-155 was an independent risk factor for DFU. The ROC curve analysis indicated that the AUC of miR-155 for the diagnosis of DFU was 0.794, with the optimum sensitivity being 96.82% and the optimum specificity of 95.93%.

CONCLUSION

The increased expression of miR-155 in peripheral blood of T2DM patients is closely related to the occurrence of DFU. MiR-155 is a potentially valuable biomarker for diagnosis and prognosis of DFU.