Impact of exosome‐loaded chitosan hydrogel in wound repair and layered dermal reconstitution in mice animal model

Chitosan-based structures for skin repair: A literature review

The use of chitosan in technological and biomedical applications has gained significant relevance due to its functional properties. Among its biological activities, its hemostatic, analgesic, antibacterial and anti-inflammatory activities make this natural biopolymer one of the most promising in the development of structures for skin repair. Its application and effects can be optimized by exploring efficient structuring techniques. In this context, this review is based on scientific evidence reported in the last decade regarding the development and use of chitosan-based structures in the skin repair process to show the most common structuring methods, the main mechanisms of action of chitosan, and its potential applications in skin repair processes. Additionally, this article brings a compilation of scientific and commercial works on the use of chitosan-based structures, in addition to vitro and/or in vivo results.

The potential of exosomes in regenerative medicine and in the diagnosis and therapies of neurodegenerative diseases and cancer

Exosomes, nanosized extracellular vesicles released by various cell types, are intensively studied for the diagnosis and treatment of cancer and neurodegenerative diseases, and they also display high usability in regenerative medicine. Emphasizing their diagnostic potential, exosomes serve as carriers of disease-specific biomarkers, enabling non-invasive early detection and personalized medicine. The cargo loading of exosomes with therapeutic agents presents an innovative strategy for targeted drug delivery, minimizing off-target effects and optimizing therapeutic interventions. In regenerative medicine, exosomes play a crucial role in intercellular communication, facilitating tissue regeneration through the transmission of bioactive molecules. While acknowledging existing challenges in standardization and scalability, ongoing research efforts aim to refine methodologies and address regulatory considerations. In summary, this review underscores the transformative potential of exosomes in reshaping the landscape of medical interventions, with a particular emphasis on cancer, neurodegenerative diseases, and regenerative medicine.

Exosome laden sprayable thermo-sensitive polysaccharide-based hydrogel for enhanced burn wound healing

Severe burns pose significant threats to patient well-being, characterized by pain, inflammation, bacterial infection, and extended recovery periods. While exosome-loaded hydrogels have demonstrated considerable promise in wound healing, current formulations often fall short of achieving optimal therapeutic efficacy for burn wounds due to challenges related to their adaptability to wound shape and limited anti-bacterial capabilities. In this study a novel exosome laden sprayable thermosensitive polysaccharide-based hydrogel (ADA-aPF127@LL18/Exo) comprising alginate dialdehyde (ADA) and aminated Pluronic F127 (aPF127) was fabricated via Schiff base reaction. ADA-aPF127@LL18/Exo exhibited sustained release of exosome and enhanced antibacterial efficacy. Furthermore, the biological assessments displayed excellent biocompatibility and enhanced in vitro cell proliferation and migration. In a deep partial thickness burn model, ADA-aPF127@LL18/Exo significantly augmented wound healing processes by accelerating epithelialization, promoting granulation tissue formation and collagen deposition, inducing hair follicle regeneration, effectively mitigating inflammatory responses, and facilitating enhanced neovascularization. In conclusion, ADA-aPF127@LL18/Exo represents a highly promising therapeutic dressing for the treatment of deep burns, exhibiting multifaceted properties conducive to efficient wound management.

Extracellular Vesicles-in-Hydrogel (EViH) targeting pathophysiology for tissue repair

Regenerative medicine endeavors to restore damaged tissues and organs utilizing biological approaches. Utilizing biomaterials to target and regulate the pathophysiological processes of injured tissues stands as a crucial method in propelling this field forward. The Extracellular Vesicles-in-Hydrogel (EViH) system amalgamates the advantages of extracellular vesicles (EVs) and hydrogels, rendering it a prominent biomaterial in regenerative medicine with substantial potential for clinical translation. This review elucidates the development and benefits of the EViH system in tissue regeneration, emphasizing the interaction and impact of EVs and hydrogels. Furthermore, it succinctly outlines the pathophysiological characteristics of various types of tissue injuries such as wounds, bone and cartilage injuries, cardiovascular diseases, nerve injuries, as well as liver and kidney injuries, underscoring how EViH systems target these processes to address related tissue damage. Lastly, it explores the challenges and prospects in further advancing EViH-based tissue regeneration, aiming to impart a comprehensive understanding of EViH. The objective is to furnish a thorough overview of EViH in enhancing regenerative medicine applications and to inspire researchers to devise innovative tissue engineering materials for regenerative medicine.

In Vitro Assessment of Chitosan-PEG Hydrogels Enriched with MSCs-Exosomes for Enhancing Wound Healing

Regenerating skin tissue remains a major challenge in medical science, especially due to the risk of scarring and prolonged healing, which becomes even more complicated in people with diabetes. Recent advancements have led to the creation of therapeutic dressings incorporating drug-delivery systems to tackle these issues. Exosomes (Exos) derived from mesenchymal stem cells (MSCs) have gained significant attention for mediating therapy without directly using cells, thanks to their natural anti-inflammatory and tissue repair properties mirroring those of MSCs. In this study, an advanced wound dressing combines chitosan (CS) and polyethylene glycol (PEG) hydrogel with adipose MSCs-derived Exos (ADMSCs-Exos). This composite, formed using a straightforward blending technique, is engineered to improve the healing process of severe skin injuries by steadily releasing Exos as the hydrogel degrades. The in vitro studies demonstrate that this hydrogel-exosome dressing greatly enhances endothelial cell migration, reduces oxidative stress, and promotes angiogenesis, crucial for effective wound healing. Additionally, real time-polymerase chain reaction (RT-PCR) analysis revealed significant upregulation of key genes involved in these processes, supporting the therapeutic potential of the hydrogel-Exo combination. These findings emphasize the potential of this hydrogel-Exos combination as an innovative and promising solution for advanced wound care.

Atopic dermatitis treatment: A comprehensive review of conventional and novel bioengineered approaches

Atopic dermatitis (AD) remains a challenging condition, with conventional treatments often leading to adverse effects and limited efficacy. This review explores the diverse landscape of AD treatments, encompassing conventional methods, novel topical and systemic therapies, and emerging bioengineered strategies. While conventional drug administration often requires high dosages or frequent administration, leading to adverse effects, targeted biologics have shown promise. Phototherapy and wet wrap therapy, while helpful, have limitations. Given these factors, the need for modern and effective therapeutic strategies for AD is pressing. Complementary or alternative therapies have garnered significant attention in recent years as a compelling treatment for AD. Among these, functionalized biomaterials and textiles with physicochemical, nanotechnology-based characteristics, or bioengineered features are some of the most common typical adjuvant therapies. The multifunctional-engineered biomaterials, as a new generation of biomedical materials, and stem cells, seem to hold tremendous promise for the treatment of dermatological diseases like AD. Biomaterials have seen great success, especially in various medical fields, due to their unique and adaptable characteristics. These materials, including collagen, PCL, and PLGA, offer unique advantages, such as biocompatibility, biodegradability, controlled drug release, and enhanced drug retention.

Inula helenium extract and lidocaine-loaded electrospun wound dressings for managing skin wounds pain and their healing: An in vitro and in vivo study

The skin injuries pose a substantial public health challenge, not only due to their physical trauma but also the accompanying pain and complexities in wound healing. In the current research, Inula helenium extract and lidocaine were loaded into electrospun PVA/calcium alginate nanofibers to promote skin wounds healing and alleviate the resulting pain. Various in vitro experiments were utilized to characterize these dressings. Wound healing potential of these constructs and their analgesic effects were studied in a rat model of skin wounds. Our developed scaffolds released the loaded drugs in a slow manner and showed antioxidative and anti-inflammatory activities. Fiber size measurement showed that drug-loaded and drug-free scaffolds had around 418.025 ± 140.11 nm and 505.51 ± 93.29 nm mean fiber size, respectively. Bacterial penetration assay confirmed that drug-loaded scaffolds reduced bacterial infiltration through the matrices. Wound healing study showed that on day 14th, the dressings loaded with inula helenium extract and lidocaine could close the wounds up to 91.26 ± 5.93%. In addition, these scaffolds significantly reduced the animals pain sensitivity. ELISA assay results implied that these dressings modulated inflammation and reduced tissue's oxidative stress.

Tailoring biomaterials for skin anti-aging

Skin aging is the phenomenon of degenerative changes in the structure and function of skin tissues over time and is manifested by a gradual loss of skin elasticity and firmness, an increased number of wrinkles, and hyperpigmentation. Skin anti-aging refers to a reduction in the skin aging phenomenon through medical cosmetic technologies. In recent years, new biomaterials have been continuously developed for improving the appearance of the skin through mechanical tissue filling, regulating collagen synthesis and degradation, inhibiting pigmentation, and repairing the skin barrier. This review summarizes the mechanisms associated with skin aging, describes the biomaterials that are commonly used in medical aesthetics and their possible modes of action, and discusses the application strategies of biomaterials in this area. Moreover, the synergistic effects of such biomaterials and other active ingredients, such as stem cells, exosomes, growth factors, and antioxidants, on tissue regeneration and anti-aging are evaluated. Finally, the possible challenges and development prospects of biomaterials in the field of anti-aging are discussed, and novel ideas for future innovations in this area are summarized.

Sodium alginate hydrogels co-encapsulated with cell free fat extract-loaded core-shell nanofibers and menstrual blood stem cells derived exosomes for acceleration of articular cartilage regeneration

This study presents a novel scaffold system comprising sodium alginate hydrogels (SAh) co-encapsulated with cell-free fat extract (CEFFE)-loaded core-shell nanofibers (NFs) and menstrual blood stem cell-derived exosomes (EXOs). The scaffold integrates the regenerative potential of EXOs and CFFFE, offering a multifaceted strategy for promoting articular cartilage repair. Coaxially electrospun core-shell NFs exhibited successful encapsulation of CEFFE and seamless integration into the SAh matrix. Structural modifications induced by the incorporation of CEFFE-NFs enhanced hydrogel porosity, mechanical strength, and degradation kinetics, facilitating cell adhesion, proliferation, and tissue ingrowth. The release kinetics of growth factors from the composite scaffold demonstrated sustained and controlled release profiles, essential for optimal tissue regeneration. In vitro studies revealed high cell viability, enhanced chondrocyte proliferation, and migration in the presence of EXOs/CEFFE-NFs@SAh composite scaffolds. Additionally, in vivo experiments demonstrated significant cartilage regeneration, with the composite scaffold outperforming controls in promoting hyaline cartilage formation and defect bridging. Overall, this study underscores the potential of EXOs and CEFFE-NFs integrated into SAh matrices for enhancing chondrocyte viability, proliferation, migration, and ultimately, articular cartilage regeneration. Future research directions may focus on elucidating underlying mechanisms and conducting long-term in vivo studies to validate clinical applicability and scalability.

An Exosome-Laden Hydrogel Wound Dressing That Can Be Point-of-Need Manufactured in Austere and Operational Environments

Skin wounds often form scar tissue during healing. Early intervention with tissue-engineered materials and cell therapies may promote scar-free healing. Exosomes and extracellular vesicles (EV) secreted by mesenchymal stromal cells (MSC) are believed to have high regenerative capacity. EV bioactivity is preserved after lyophilization and storage to enable use in remote and typically resource-constrained environments. We developed a bioprinted bandage containing reconstituted EVs that can be fabricated at the point-of-need. An alginate/carboxymethyl cellulose (CMC) biomaterial ink was prepared, and printability and mechanical properties were assessed with rheology and compression testing. Three-dimensional printed constructs were evaluated for Young's modulus relative to infill density and crosslinking to yield material with stiffness suitable for use as a wound dressing. We purified EVs from human MSC-conditioned media and characterized them with nanoparticle tracking analysis and mass spectroscopy, which gave a peak size of 118 nm and identification of known EV proteins. Fluorescently labeled EVs were mixed to form bio-ink and bioprinted to characterize EV release. EV bandages were bioprinted on both a commercial laboratory bioprinter and a custom ruggedized 3D printer with bioprinting capabilities, and lyophilized EVs, biomaterial ink, and thermoplastic filament were deployed to an austere Arctic environment and bioprinted. This work demonstrates that EVs can be bioprinted with an alginate/CMC hydrogel and released over time when in contact with a skin-like substitute. The technology is suitable for operational medical applications, notably in resource-limited locations, including large-scale natural disasters, humanitarian crises, and combat zones.

Meta-analysis study of small extracellular vesicle nursing application therapies for healing of wounds and skin regeneration

We designed and performed this meta-analysis to investigate the impact of the application of extracellular small vesicle therapies on regeneration of skin and wound healing. The findings of this study were computed using fixed or random effect models. The mean differences (MDs), and odds ratio (ORs) with their 95% confidence intervals (CIs) were calculated. In this study, 43 publications were included, encompassing 530 animals with artificial wounds. Small extracellular vesicle therapy had a significant greater rate of wound closure (MD, 24.0; 95% CI, 19.98-28.02, P < 0.001), lower scar width (MD, -191.33; 95%CI, -292.26--90.4, P < 0.001), and higher blood vessel density (MD,36.11; 95%CI, 19.02-53.20, P < 0.001) compared to placebo. Our data revealed that small extracellular vesicle therapy had a significantly higher regeneration of skin and healing of wounds based on the results of wound closure rate, lower scar width, and higher blood vessel density compared to placebo. Future studies with larger sample size are needed.

l-Carnosine loaded on carboxymethyl cellulose hydrogels for promoting wound healing

Wound management remains a challenge in clinical practice. Nowadays, patients have an increasing demand for wound repair with enhanced speed and quality; therefore, there is a great need to seek therapeutic strategies that can promote rapid and effective wound healing. In this study, we developed a carboxymethyl cellulose hydrogel loaded with l-carnosine (CRN@hydrogel) for potential application as a wound dressing. In vitro experiments confirmed that CRN@hydrogel can release over 80% of the drug within 48 h and demonstrated its favorable cytocompatibility and blood compatibility, thus establishing its applicability for safe utilization in clinical practice. Using a rat model, we found that this hydrogel could promote and accelerate wound healing more effectively. These results indicate that the novel hydrogel can serve as an efficient therapeutic strategy for wound treatment.

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.

Tissue regeneration properties of hydrogels derived from biological macromolecules: A review

The successful tissue engineering depends on the development of biologically active scaffolds that possess optimal characteristics to effectively support cellular functions, maintain structural integrity and aid in tissue regeneration. Hydrogels have emerged as promising candidates in tissue regeneration due to their resemblance to the natural extracellular matrix and their ability to support cell survival and proliferation. The integration of hydrogel scaffold into the polymer has a variable impact on the pseudo extracellular environment, fostering cell growth/repair. The modification in size, shape, surface morphology and porosity of hydrogel scaffolds has consequently paved the way for addressing diverse challenges in the tissue engineering process such as tissue architecture, vascularization and simultaneous seeding of multiple cells. The present review provides a comprehensive update on hydrogel production using natural and synthetic biomaterials and their underlying mechanisms. Furthermore, it delves into the application of hydrogel scaffolds in tissue engineering for cardiac tissues, cartilage tissue, adipose tissue, nerve tissue and bone tissue. Besides, the present article also highlights various clinical studies, patents, and the limitations associated with hydrogel-based scaffolds in recent times.

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

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

Development of pro-angiogenic skin substitutes for wound healing

Wounds pose significant challenges to public health, primarily due to the loss of the mechanical integrity and barrier function of the skin and impaired angiogenesis, causing physical morbidities and psychological trauma to affect patients. Reconstructing the vasculature of the wound bed is crucial for promoting wound healing, reducing scar formation and enhancing the quality of life for patients. The development of pro-angiogenic skin substitutes has emerged as a promising strategy to facilitate vascularization and expedite the healing process of burn wounds. This review provides an overview of the various types of skin substitutes employed in wound healing, explicitly emphasising those designed to enhance angiogenesis. Synthetic scaffolds, biological matrices and tissue-engineered constructs incorporating stem cells and primary cells, cell-derived extracellular vesicles (EVs), pro-angiogenic growth factors and peptides, as well as gene therapy-based skin substitutes are thoroughly examined. The review summarises the existing challenges, future directions and potential innovations in pro-angiogenic dressing for skin substitutes. It highlights the need for continued research to develop new technologies and combine multiple strategies and factors, and to overcome obstacles and advance the field, ultimately leading to improved outcomes for wound patients.

Exosomal noncoding RNA: A potential therapy for retinal vascular diseases

Exosomes are extracellular vesicles that can contain DNA, RNA, proteins, and metabolites. They are secreted by cells and play a regulatory role in various biological responses by mediating cell-to-cell communication. Moreover, exosomes are of interest in developing therapies for retinal vascular disorders because they can deliver various substances to cellular targets. According to recent research, exosomes can be used as a strategy for managing retinal vascular diseases, and they are being investigated for therapeutic purposes in eye conditions, including glaucoma, dry eye syndrome, retinal ischemia, diabetic retinopathy, and age-related macular degeneration. However, the role of exosomal noncoding RNA in retinal vascular diseases is not fully understood. Here, we reviewed the latest research on the biological role of exosomal noncoding RNA in treating retinal vascular diseases. Research has shown that noncoding RNAs, including microRNAs, circular RNAs, and long noncoding RNAs play a significant role in the regulation of retinal vascular diseases. Furthermore, through exosome engineering, the expression of relevant noncoding RNAs in exosomes can be controlled to regulate retinal vascular diseases. Therefore, this review suggests that exosomal noncoding RNA could be considered as a biomarker for diagnosis and as a therapeutic target for treating retinal vascular disease.

Bone tissue regeneration by 58S bioactive glass scaffolds containing exosome: an in vivo study

Exosomes, the naturally secreted nanocarriers of cells, have recently been demonstrated to have therapeutic benefits in a variety of disease models where parent cells are not present. However, the use of exosomes in bone defect regeneration has been unusual, and little is documented about the underlying processes. In recent study we produced and characterized exosomes derived human endometrial mesenchymal stem stromal cells and 58S bioactive glass scaffolds; in following, in this research exosome loaded scaffolds synthetized and release of exosome, porosity and bioactivity of them were assessed. More over the effect of scaffolds on repair of critical-size bone defects in rat's calvaria was evaluated by histological examination and micro computed tomography (µ CT). The findings confirmed that constructed porous scaffolds consistently release exosomes; additionally, in vivo findings including Hematoxilin & Eosin staining, Immunohistochemistry, Masson's trichrome, histomorphometric analysis, and µ CT clarified that our implant has osteogenic properties. We discovered that Exo-treated scaffolds might promote osteogenesis especially compared to pure scaffolds, indicating that produced scaffolds containing exosomes could be a potential replacement in bone tissue engineering.

Alginate hydrogel-PCL/gelatin nanofibers composite scaffold containing mesenchymal stem cells-derived exosomes sustain release for regeneration of tympanic membrane perforation

Exosomes are among the most effective therapeutic tools for tissue engineering. This study demonstrates that a 3D composite scaffold containing exosomes can promote regeneration in rat tympanic membrane perforation (TMP). The scaffolds were characterized using scanning electron microscopy (SEM), degradation, PBS adsorption, swelling, porosity, and mechanical properties. To confirm the isolation of exosomes from human adipose-derived mesenchymal stem cells (hAMSCs), western blot, SEM, and dynamic light scattering (DLS) were performed. The Western blot test confirmed the presence of exosomal surface markers CD9, CD81, and CD63. The SEM test revealed that the isolated exosomes had a spherical shape, while the DLS test indicated an average diameter of 82.5 nm for these spherical particles. MTT assays were conducted to optimize the concentration of hAMSCs-exosomes in the hydrogel layer of the composite. Exosomes were extracted on days 3 and 7 from an alginate hydrogel containing 100 and 200 μg/mL of exosomes, with 100 μg/mL identified as the optimal value. The optimized composite scaffold demonstrated improved growth and migration of fibroblast cells. Animal studies showed complete tympanic membrane regeneration (TM) after five days. These results illustrate that a scaffold containing hAMSC-exosomes can serve as an appropriate tissue-engineered scaffold for enhancing TM regeneration.

Pharmaceutical applications of chitosan in skin regeneration: A review

Skin regeneration is the process that restores damaged tissues. When the body experiences trauma or surgical incisions, the skin and tissues on the wound surface become damaged. The body repairs this damage through complex physiological processes to restore the original structural and functional states of the affected tissues. Chitosan, a degradable natural bioactive polysaccharide, has attracted widespread attention partly owing to its excellent biocompatibility and antimicrobial properties; additionally, a modified form of this compound has been shown to promote skin regeneration. This review evaluates the recent research progress in the application of chitosan to promote skin regeneration. First, we discuss the basic principles of the extraction and preparation processes of chitosan from its source. Subsequently, we describe the functional properties of chitosan and the optimization of these properties through modification. We then focus on the existing chitosan-based biomaterials developed for clinical applications and their corresponding effects on skin regeneration, particularly in cases of diabetic and burn wounds. Finally, we explore the challenges and prospects associated with the use of chitosan in skin regeneration. Overall, this review provides a reference for related research and contributes to the further development of chitosan-based products in cutaneous skin regeneration.

Hydrogel-mediated extracellular vesicles for enhanced wound healing: the latest progress, and their prospects for 3D bioprinting

Extracellular vesicles have shown promising tissue recovery-promoting effects, making them increasingly sought-after for their therapeutic potential in wound treatment. However, traditional extracellular vesicle applications suffer from limitations such as rapid degradation and short maintenance during wound administration. To address these challenges, a growing body of research highlights the role of hydrogels as effective carriers for sustained extracellular vesicle release, thereby facilitating wound healing. The combination of extracellular vesicles with hydrogels and the development of 3D bioprinting create composite hydrogel systems boasting excellent mechanical properties and biological activity, presenting a novel approach to wound healing and skin dressing. This comprehensive review explores the remarkable mechanical properties of hydrogels, specifically suited for loading extracellular vesicles. We delve into the diverse sources of extracellular vesicles and hydrogels, analyzing their integration within composite hydrogel formulations for wound treatment. Different composite methods as well as 3D bioprinting, adapted to varying conditions and construction strategies, are examined for their roles in promoting wound healing. The results highlight the potential of extracellular vesicle-laden hydrogels as advanced therapeutic tools in the field of wound treatment, offering both mechanical support and bioactive functions. By providing an in-depth examination of the various roles that these composite hydrogels can play in wound healing, this review sheds light on the promising directions for further research and development. Finally, we address the challenges associated with the application of composite hydrogels, along with emerging trends of 3D bioprinting in this domain. The discussion covers issues such as scalability, regulatory considerations, and the translation of this technology into practical clinical settings. In conclusion, this review underlines the significant contributions of hydrogel-mediated extracellular vesicle therapy to the field of 3D bioprinting and wound healing and tissue regeneration. It serves as a valuable resource for researchers and practitioners alike, fostering a deeper understanding of the potential benefits, applications, and challenges involved in utilizing composite hydrogels for wound treatment.

Extracellular vesicles and their engineering strategies, delivery systems, and biomedical applications

Extracellular vesicles are nanoscale vesicles that can be secreted by all cell types, are intracellular in origin and have the same composition as their parent cells, play a key role in intercellular communication in organismal health and disease, and are now often used as biomarkers of disease and therapeutic agents in biomedical research. When injected locally or systemically, they have the ability to provide a variety of therapeutic effects, for example, regeneration of skin damage or restoration of cardiac function. However, direct injection of extracellular vesicles may result in their rapid clearance from the injection site.In order to maintain the biological activity of extracellular vesicles and to control the release of effective concentrations for better therapeutic efficacy during long-term disease treatment, the design of an optimized drug delivery system is necessary and different systems for the continuous delivery of extracellular vesicles have been developed. This paper first provides an overview of the biogenesis, composition and physiological function of extracellular vesicles, followed by a review of different strategies for extracellular vesicle isolation and methods for engineering extracellular vesicles. In addition, this paper reviews the latest extracellular vesicle delivery platforms such as micro-nanoparticles, injectable hydrogels, microneedles and scaffold patches. At the same time, the research progress and key cases of extracellular vesicle delivery systems in the field of biomedical therapeutics are described. Finally, the challenges and future trends of extracellular vesicle delivery are discussed.

Extracellular vesicle biopotentiated hydrogels for diabetic wound healing: The art of living nanomaterials combined with soft scaffolds

Diabetic wounds (DWs) pose a major challenge for the public health system owing to their high incidence, complex pathogenesis, and long recovery time; thus, there is an urgent need to develop innovative therapies to accelerate the healing process of diabetic wounds. As natural nanovesicles, extracellular vesicles (EVs) are rich in sources with low immunogenicity and abundant nutritive molecules and exert potent therapeutic effects on diabetic wound healing. To avoid the rapid removal of EVs, a suitable delivery system is required for their controlled release. Owing to the advantages of high porosity, good biocompatibility, and adjustable physical and chemical properties of hydrogels, EV biopotentiated hydrogels can aid in achieving precise and favorable therapy against diabetic wounds. This review highlights the different design strategies, therapeutic effects, and mechanisms of EV biopotentiated hydrogels. We also discussed the future challenges and opportunities of using EV biopotentiated hydrogels for diabetic wound healing.

Human umbilical cord mesenchymal stem cell-derived exosomes combined with gelatin methacryloyl hydrogel to promote fractional laser injury wound healing

To investigate whether human umbilical cord mesenchymal stem cell-derived exosomes combined with gelatin methacryloyl (GelMA) hydrogel are beneficial in promoting healing of laser-injured skin wounds in mice. Supernatants of cultured human umbilical cord mesenchymal stem cells (HUC-MSCs) were collected to obtain human umbilical cord MSC-derived exosomes (HUC-MSCs-Exos), which were combined with GelMA hydrogel complex to treat a mouse fractional laser injury model. The study was divided into PBS group, EX (HUC-MSCs-Exos) group, GEL (GelMA hydrogel) group and EX+GEL (HUC-MSCs-Exos combined with GelMA hydrogel) group. The healing of laser-injured skin in each group was observed by gross view and dermatoscopy, and changes in skin structure, angiogenesis and proliferation-related indexes were observed during the healing process of laser-injured skin in each group. The results of the animal experiments showed that the EX and GEL groups alone and the EL+EX group exhibited less inflammatory response compared to the PBS group. The EX and GEL groups showed marked tissue proliferation and favourable angiogenesis, which promoted the wound healing well. The GEL+EX group had the most significant promotion of wound healing compared to the PBS group. qPCR results showed that the expression levels of proliferation-related factors, including KI67 and VEGF and angiogenesis-related factor CD31, were significantly higher in the GEL+EX group than in the other groups, with a time-dependent effect. The combination of HUC-MSCs-Exos and GelMA hydrogel is beneficial in reducing the early inflammatory response of laser-injured skin in mice and promoting its proliferation and angiogenesis, which in turn promotes wound healing.

Advanced micro-/nanotechnologies for exosome encapsulation and targeting in regenerative medicine

Exosomes, a subset of vesicles generated from cell membranes, are crucial for cellular communication. Exosomes' innate qualities have been used in recent studies to create nanocarriers for various purposes, including medication delivery and immunotherapy. As a result, a wide range of approaches has been designed to utilize their non-immunogenic nature, drug-loading capacity, or targeting ability. In this study, we aimed to review the novel methods and approaches in exosome engineering for encapsulation and targeting in regenerative medicine. We have assessed and evaluated each method's efficacy, advantages, and disadvantages and discussed the results of related studies. Even though the therapeutic role of non-allogenic exosomes has been demonstrated in several studies, their application has certain limitations as these particles are neither fully specific to target tissue nor tissue retainable. Hence, there is a strong demand for developing more efficient encapsulation methods along with more accurate and precise targeting methods, such as 3D printing and magnetic nanoparticle loading in exosomes, respectively.

Enhanced wound healing and hemostasis with exosome-loaded gelatin sponges from human umbilical cord mesenchymal stem cells

BACKGROUND

Rapid wound healing remains a pressing clinical challenge, necessitating studies to hasten this process. A promising approach involves the utilization of human umbilical cord mesenchymal stem cells (hUC-MSCs) derived exosomes. The hypothesis of this study was that these exosomes, when loaded onto a gelatin sponge, a common hemostatic material, would enhance hemostasis and accelerate wound healing.

AIM

To investigate the hemostatic and wound healing efficacy of gelatin sponges loaded with hUC-MSCs-derived exosomes.

METHODS

Ultracentrifugation was used to extract exosomes from hUC-MSCs. Nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and western blot techniques were used to validate the exosomes. In vitro experiments were performed using L929 cells to evaluate the cytotoxicity of the exosomes and their impact on cell growth and survival. New Zealand rabbits were used for skin irritation experiments to assess whether they caused adverse skin reactions. Hemolysis test was conducted using a 2% rabbit red blood cell suspension to detect whether they caused hemolysis. Moreover, in vivo experiments were carried out by implanting a gelatin sponge loaded with exosomes subcutaneously in Sprague-Dawley (SD) rats to perform biocompatibility tests. In addition, coagulation index test was conducted to evaluate their impact on blood coagulation. Meanwhile, SD rat liver defect hemostasis model and full-thickness skin defect model were used to study whether the gelatin sponge loaded with exosomes effectively stopped bleeding and promoted wound healing.

RESULTS

The NTA, TEM, and western blot experimental results confirmed that exosomes were successfully isolated from hUC-MSCs. The gelatin sponge loaded with exosomes did not exhibit significant cell toxicity, skin irritation, or hemolysis, and they demonstrated good compatibility in SD rats. Additionally, the effectiveness of the gelatin sponge loaded with exosomes in hemostasis and wound healing was validated. The results of the coagulation index experiment indicated that the gelatin sponge loaded with exosomes had significantly better coagulation effect compared to the regular gelatin sponge, and they showed excellent hemostatic performance in a liver defect hemostasis model. Finally, the full-thickness skin defect healing experiment results showed significant improvement in the healing process of wounds treated with the gelatin sponge loaded with exosomes compared to other groups.

CONCLUSION

Collectively, the gelatin sponge loaded with hUC-MSCs-derived exosomes is safe and efficacious for promoting hemostasis and accelerating wound healing, warranting further clinical application.

Polysaccharide hydrogel platforms as suitable carriers of liposomes and extracellular vesicles for dermal applications

Lipid-based nanocarriers have been extensively investigated for their application in drug delivery. Particularly, liposomes are now clinically established for treating various diseases such as fungal infections. In contrast, extracellular vesicles (EVs) - small cell-derived nanoparticles involved in cellular communication - have just recently sparked interest as drug carriers but their development is still at the preclinical level. To drive this development further, the methods and technologies exploited in the context of liposome research should be applied in the domain of EVs to facilitate and accelerate their clinical translation. One of the crucial steps for EV-based therapeutics is designing them as proper dosage forms for specific applications. This review offers a comprehensive overview of state-of-the-art polysaccharide-based hydrogel platforms designed for artificial and natural vesicles with application in drug delivery to the skin. We discuss their various physicochemical and biological properties and try to create a sound basis for the optimization of EV-embedded hydrogels as versatile therapeutic avenues.

Enhanced therapeutic effects of mesenchymal stem cell-derived extracellular vesicles within chitosan hydrogel in the treatment of diabetic foot ulcers

Extracellular vesicles (EVs) derived from human umbilical cord mesenchymal stem cells (hUCMSCs) have emerged as promising candidates for cell-free therapy in various diseases, including chronic cutaneous wounds. However, the lack of standardized protocols for EVs' preparation and identification poses a significant challenge to their clinical application. Thus, the objective was to develop a safe and efficient method for the large-scale production of hUCMSC-derived EVs while establishing a comprehensive identification protocol encompassing morphology, particle size distribution, protein expression, and purity. This study observed that most of the EVs acquired through the protocol exhibited either a cup-shaped or round-shaped structure, with a median diameter of ~73.25 nm. The proportions of EVs positive for CD9, CD63, and CD81 were 37.5%, 38.6%, and 19.8%, respectively. To enhance their therapeutic potential in wound treatment, EVs were incorporated into chitosan hydrogel, forming chitosan hydrogel-EVs (CS-EVs). Furthermore, it was demonstrated that CS-EVs exhibited continuous release of EVs into the surrounding environment and, importantly, that the released EVs were internalized by human umbilical vein endothelial cells (HUVECs), resulting in significant enhancement of cell migration and angiogenesis. Additionally, in a rat model of diabetic foot ulcers, CS-EVs demonstrated a robust therapeutic effect in promoting wound healing. Following a 15-day treatment period, the group treated with CS-EVs demonstrated an impressive 93.3% wound closure ability, accompanied by a high degree of re-epithelialization. In contrast, the control group exhibited only a 71.5% reduction in wound size. In summary, this study offers solutions for the purification, characterization, and application of EVs in clinical wound treatment. These results not only offer fresh perspectives on the involvement of hUCMSC-derived EVs in wound healing but also introduce a non-invasive approach for applying EVs that holds practical significance in skin repair.

Mesenchymal stem cell-derived extracellular vesicles in skin wound healing: roles, opportunities and challenges

Skin wounds are characterized by injury to the skin due to trauma, tearing, cuts, or contusions. As such injuries are common to all human groups, they may at times represent a serious socioeconomic burden. Currently, increasing numbers of studies have focused on the role of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) in skin wound repair. As a cell-free therapy, MSC-derived EVs have shown significant application potential in the field of wound repair as a more stable and safer option than conventional cell therapy. Treatment based on MSC-derived EVs can significantly promote the repair of damaged substructures, including the regeneration of vessels, nerves, and hair follicles. In addition, MSC-derived EVs can inhibit scar formation by affecting angiogenesis-related and antifibrotic pathways in promoting macrophage polarization, wound angiogenesis, cell proliferation, and cell migration, and by inhibiting excessive extracellular matrix production. Additionally, these structures can serve as a scaffold for components used in wound repair, and they can be developed into bioengineered EVs to support trauma repair. Through the formulation of standardized culture, isolation, purification, and drug delivery strategies, exploration of the detailed mechanism of EVs will allow them to be used as clinical treatments for wound repair. In conclusion, MSC-derived EVs-based therapies have important application prospects in wound repair. Here we provide a comprehensive overview of their current status, application potential, and associated drawbacks.

Therapeutic Potential of Extracellular Vesicles from Different Stem Cells in Chronic Wound Healing

Wound healing has long been a complex problem, especially in chronic wounds. Although debridement, skin grafting, and antimicrobial dressings have been used to treat chronic wounds, their treatment period is long, expensive, and has specific rejection reactions. The poor treatment results of traditional methods have caused psychological stress to patients and a substantial economic burden to society. Extracellular vesicles (EVs) are nanoscale vesicles secreted by cells. They play an essential role in intercellular communication. Numerous studies have confirmed that stem cell-derived extracellular vesicles (SC-EVs) can inhibit overactive inflammation, induce angiogenesis, promote re-epithelization, and reduce scar formation. Therefore, SC-EVs are expected to be a novel cell-free strategy for chronic wound treatment. We first summarize the pathological factors that hinder wound healing and discuss how SC-EVs accelerate chronic wound repair. And then, we also compare the advantages and disadvantages of different SC-EVs for chronic wound treatment. Finally, we discuss the limitations of SC-EVs usage and provide new thoughts for future SC-EVs research in chronic wound treatment.

Extracellular vesicle-based biovectors in chronic wound healing: Biogenesis and delivery approaches

Chronic wounds remain an unresolved medical issue because of major social and therapeutic repercussions that require extensive focus. Recent related theragnostic focuses only on wound management and is not effectively promoting chronic wound healing. The rising number of patients with either under-healing or over-healing wounds highlights the ineffectiveness of current wound-healing treatments, and thus, there is an unmet need to focus on alternative treatments. To cover this gap, extracellular vesicles (EVs), for targeted delivery of therapeutics, are emerging as a potential therapy to treat both acute and persistent wounds. To address these issues, we explore the core biology of EVs, associated pharmacology, comprehension of immunogenic outcomes, and potential for long-term wound treatment with improved effectiveness and their nonacceptable side effects. Additionally, the therapeutic role of EVs in severe wound infections through biogenetic moderation, in combination with biomaterials (functional in nature), as well as drug carriers that can offer opportunities for the development of new treatments for this long-term condition, are also carefully elaborated, with an emphasis on biomaterial-based drug delivery systems. It is observed that exploring difficulties and potential outcomes of clinical translation of EV-based therapeutics for wound management has the potential to be adopted as a future therapy.

Extracellular vesicles: Emerged as a promising strategy for regenerative medicine

Cell transplantation therapy has certain limitations including immune rejection and limited cell viability, which seriously hinder the transformation of stem cell-based tissue regeneration into clinical practice. Extracellular vesicles (EVs) not only possess the advantages of its derived cells, but also can avoid the risks of cell transplantation. EVs are intelligent and controllable biomaterials that can participate in a variety of physiological and pathological activities, tissue repair and regeneration by transmitting a variety of biological signals, showing great potential in cell-free tissue regeneration. In this review, we summarized the origins and characteristics of EVs, introduced the pivotal role of EVs in diverse tissues regeneration, discussed the underlying mechanisms, prospects, and challenges of EVs. We also pointed out the problems that need to be solved, application directions, and prospects of EVs in the future and shed new light on the novel cell-free strategy for using EVs in the field of regenerative medicine.

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.

Curcumin-loaded human endometrial stem cells derived exosomes as an effective carrier to suppress alpha-synuclein aggregates in 6OHDA-induced Parkinson's disease mouse model

Parkinson disease (PD) is considered as one of the most worldwide neurodegenerative disorders. The major reasons associated to neurodegeneration process of PD pathogenesis are oxidative stress. Many studies reported that natural antioxidant molecules, especially, curcumin can suppress inflammatory pathways and preserve dopaminergic neurons damage in PD. Further, the poor pharmacokinetics, instability of chemical structure because of fast hydrolytic degradation at physiologic condition and especially, the presence of the blood brain barrier (BBB) has regarded as a considerable restriction factor for transfer of neurotherapeutic molecules to the brain tissue. The present research aims to the fabrication of nanoformulated curcumin loaded human endometrial stem cells derived exosomes (hEnSCs EXOs-Cur) to study on enhancing curcumin penetration to the brain across BBB and to improve anti- Parkinsonism effects of curcumin against neural death and alpha-synuclein aggregation. hEnSCs EXOs-Cur characterization results demonstrated the accurate size and morphology of formulated curcumin loaded exosomes with a proper stability and sustained release profile. In vivo studies including behavioral, Immunohistochemical and molecular evaluations displayed that novel formulation of hEnSCs EXO-Cur is able to cross BBB, enhance motor uncoordinated movements, suppress the aggregation of αS protein and rescue neuronal cell death through elevation of BCL2 expression level as an anti-apoptotic protein and the expression level reduction of BAX and Caspase 3 as apoptotic markers.

Extracellular Vesicle-Based Hydrogels for Wound Healing Applications

Hydrogels and extracellular vesicle-based therapies have been proposed as emerging therapeutic assets in wound closure. The combination of these elements has given good results in managing chronic and acute wounds. The intrinsic characteristics of the hydrogels in which the extracellular vesicles (EVs) are loaded allow for overcoming barriers, such as the sustained and controlled release of EVs and the maintenance of the pH for their conservation. In addition, EVs can be obtained from different sources and through several isolation methods. However, some barriers must be overcome to transfer this type of therapy to the clinic, for example, the production of hydrogels containing functional EVs and identifying long-term storage conditions for EVs. The aim of this review is to describe the reported EV-based hydrogel combinations, along with the obtained results, and analyze future perspectives.

Exosomes and exosome-loaded scaffolds: Characterization and application in modern regenerative medicine

Exosomes (EXOs) are extracellular vesicles derived from the endosome. These heterogeneous nanoparticles (30-150 nm) are secreted from various cells and play important biological roles in intercellular communication. EXOs have received much attention for application in regenerative therapies and tissue repair due to their stability, biosafety, and functional versatility. However, in their free forms, "EXOs have poor bioavailability" at the site of action and are devoid of controlled-release mechanisms. These issues have been largely remedied by scaffolding EXOs with appropriate biomaterials such as hydrogels to create EXOs -loaded scaffold (ELS). These biomaterial-based scaffolds can be rationally designed and functionalized to enhance various aspects of ELS including bioavailability, biocompatibility, and loading/release control. Additionally, the ELS are superior to free EXOs due to reduced injection-related side effects. This review article provides a comprehensive and updated account of EXOs and ELS isolation, characterization, and application in regenerative medicine with a focus on soft tissue repair. We also offer insights into the advantages of ELS therapy compared to stem cell therapy towards application in wound healing, cardiac and bone repair. ELS promotes cell migration to the scaffold and will cause better homing of exosomes. Different types of scaffolds are made and each one can be modified based on the repair in the target tissues so that the reactions between the scaffold and exosome take place properly and effective signals are created for tissue repair.

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.

Idebenone-loaded wound dressings promote diabetic wound healing through downregulation of Il1b, Nfkb genes and upregulation of Fgf2 gene

Reactive oxygen species (ROS) are overproduced in diabetic wounds and retard the healing response. Considering the antioxidative function of idebenone, its exogenous administration may quench excessive ROS and promote diabetic wound healing. In the current study, idebenone was loaded into polyvinyl alcohol (PVA) /calcium alginate scaffolds at three different concentrations of 1 w/w%, 2 w/w%, and 3 w/w%. Various in vitro experiments were performed to characterize the developed wound dressings. Cell viability assay showed that scaffolds loaded with 1 w/w% idebenone had significantly better protection under oxidative stress and exhibited higher cell viability. Therefore, the dressings containing 1% drug was chosen to treat diabetic wounds in rat model. Wound healing assay showed that the dressings loaded with 1% drug had significantly higher rate of wound size reduction, collagen deposition, and epithelial thickness. Gene expression study showed that wound healing was accompanied by modulation of inflammatory response, protection against oxidative stress, and increasing angiogenesis-related genes. This preliminary research suggests that PVA/calcium alginate/1% idebenone scaffolds can be considered as a potential treatment modality to treat diabetic wounds in the clinic. However, more extensive studies at gene and protein expression levels are required to understand its exact mechanism of healing effects.

Differentiation of human endometrial stem cells encapsulated in alginate hydrogel into oocyte-like cells

INTRODUCTION

Human endometrial mesenchymal stem cells (hEnMSCs) are a rich source of mesenchymal stem cells (MSCs) with multi-lineage differentiation potential, making them an intriguing tool in regenerative medicine, particularly for the treatment of reproductive and infertility issues. The specific process of germline cell-derived stem cell differentiation remains unknown, the aim is to study novel ways to achieve an effective differentiation method that produces adequate and functioning human gamete cells.

METHODS

We adjusted the optimum retinoic acid (RA) concentration for enhancement of germ cell-derived hEnSCs generation in 2D cell culture after 7 days in this study. Subsequently, we developed a suitable oocyte-like cell induction media including RA and bone morphogenetic protein 4 (BMP4), and studied their effects on oocyte-like cell differentiation in 2D and 3D cell culture media utilizing cells encapsulated in alginate hydrogel.

RESULTS

Our results from microscopy analysis, real-time PCR, and immunofluorescence tests revealed that 10 µM RA concentration was the optimal dose for inducing germ-like cells after 7 days. We examined the alginate hydrogel structural characteristics and integrity by rheology analysis and SEM microscope. We also demonstrated encapsulated cell viability and adhesion in the manufactured hydrogel. We propose that in 3D cell cultures in alginate hydrogel, an induction medium containing 10 µM RA and 50 ng/mL BMP4 can enhance hEnSC differentiation into oocyte-like cells.

CONCLUSION

The production of oocyte-like cells using 3D alginate hydrogel may be viable in vitro approach for replacing gonad tissues and cells.

Extracellular vesicles: A potential future strategy for dental and maxillofacial tissue repair and regeneration

Extracellular vesicles (EVs), nano-sized bilayer membrane structures containing lipids, proteins and nucleic acids, play key roles in intercellular communication. Compared to stem cells, EVs have lower tumorigenicity and immunogenicity, are easier to manage and cause fewer ethic problems. In recent years, EVs have emerged as a potential solution for tissue regeneration in stomatology through cell-free therapies. The present review focuses on the role of EVs in dental and maxillofacial tissue repair and regeneration, including in dental and periodontal tissue, maxilla and mandible bone, temporomandibular joint cartilage, peripheral nerve and soft tissue. We also make a brief overview on the mechanism of EVs performing functions. However, limitations and challenges in clinical application of EVs still exist and should be addressed in future researches.

Extracellular Vesicles in Tissue Engineering: Biology and Engineered Strategy

Extracellular vesicles (EVs), acting as an important ingredient of intercellular communication through paracrine actions, have gained tremendous attention in the field of tissue engineering (TE). Moreover, these nanosized extracellular particles (30-140 nm) can be incorporated into biomaterials according to different principles to facilitate signal delivery in various regenerative processes directly or indirectly. Bioactive biomaterials as the carrier will extend the retention time and realize the controlled release of EVs, which further enhance their therapeutic efficiency in tissue regeneration. Herein, the basic biological characteristics of EVs are first introduced, and then their outstanding performance in exerting direct impacts on target cells in tissue regeneration as well as indirect effects on promoting angiogenesis and regulating the immune environment, due to specific functional components of EVs (nucleic acid, protein, lipid, etc.), is emphasized. Furthermore, different design ideas for suitable EV-loaded biomaterials are also demonstrated. In the end, this review also highlights the engineered strategies, which aim at solving the problems related to natural EVs such as highly heterogeneous functions, inadequate tissue targeting capabilities, insufficient yield and scalability, etc., thus promoting the therapeutic pertinence and clinical potential of EV-based approaches in TE.

Behind the Scenes of Extracellular Vesicle Therapy for Skin Injuries and Disorders

Significance: Skin wounds and disorders compromise the protective functions of skin and patient quality of life. Although accessible on the surface, they are challenging to address due to paucity of effective therapies. Exogenous extracellular vesicles (EVs) and cell-free derivatives of adult multipotent stromal cells (MSCs) are developing as a treatment modality. Knowledge of origin MSCs, EV processing, and mode of action is necessary for directed use of EVs in preclinical studies and methodical translation. Recent Advances: Nanoscale to microscale EVs, although from nonskin cells, induce functional responses in cutaneous wound cellular milieu. EVs allow a shift from cell-based to cell-free/derived modalities by carrying the MSC beneficial factors but eliminating risks associated with MSC transplantation. EVs have demonstrated striking efficacy in resolution of preclinical wound models, specifically within the complexity of skin structure and wound pathology. Critical Issues: To facilitate comparison across studies, tissue sources and processing of MSCs, culture conditions, isolation and preparations of EVs, and vesicle sizes require standardization as these criteria influence EV types and contents, and potentially determine the induced biological responses. Procedural parameters for all steps preceding the actual therapeutic administration may be the key to generating EVs that demonstrate consistent efficacy through known mechanisms. We provide a comprehensive review of such parameters and the subsequent tissue, cellular and molecular impact of the derived EVs in different skin wounds/disorders. Future Directions: We will gain more complete knowledge of EV-induced effects in skin, and specificity for different wounds/conditions. The safety and efficacy of current preclinical xenogenic applications will favor translation into allogenic clinical applications of EVs as a biologic.

Role of Exosomes in Pharyngucutaneous Fistula After Total Laryngectomy

Pharyngocutaneous fistula is the most common complication after total laryngectomy and is difficult to heal. Although conservative treatment and surgical repair are effective, they often take longer and additional trips to the operating room, which undoubtedly increases the financial burden on patients. Especially in combination with diseases such as diabetes and hypertension, which affect the efficacy of surgery. Adding growth factors into the repair material can promote fibroblast proliferation, angiogenesis, and accelerate wound healing. A substantial number of studies have shown that a type of nanoscale extracellular vesicle, called exosomes, facilitates organization repair by promoting blood vessel production, protein polysaccharides, and collagen deposition, thereby representing a new type of cellular therapy. At present, there is little research on the application of exosomes in pharyngocutaneous fistula regeneration after total laryngectomy. In this review, we summarize the biological characteristics of exosomes and their application in biomedical science, and highlight their application prospects in pharyngocutaneous fistula regeneration after total laryngectomy.

Biomaterials and Extracellular Vesicle Delivery: Current Status, Applications and Challenges

In this review, we will discuss the current status of extracellular vesicle (EV) delivery via biopolymeric scaffolds for therapeutic applications and the challenges associated with the development of these functionalized scaffolds. EVs are cell-derived membranous structures and are involved in many physiological processes. Naïve and engineered EVs have much therapeutic potential, but proper delivery systems are required to prevent non-specific and off-target effects. Targeted and site-specific delivery using polymeric scaffolds can address these limitations. EV delivery with scaffolds has shown improvements in tissue remodeling, wound healing, bone healing, immunomodulation, and vascular performance. Thus, EV delivery via biopolymeric scaffolds is becoming an increasingly popular approach to tissue engineering. Although there are many types of natural and synthetic biopolymers, the overarching goal for many tissue engineers is to utilize biopolymers to restore defects and function as well as support host regeneration. Functionalizing biopolymers by incorporating EVs works toward this goal. Throughout this review, we will characterize extracellular vesicles, examine various biopolymers as a vehicle for EV delivery for therapeutic purposes, potential mechanisms by which EVs exert their effects, EV delivery for tissue repair and immunomodulation, and the challenges associated with the use of EVs in scaffolds.

Prospects and Challenges of Electrospun Cell and Drug Delivery Vehicles to Correct Urethral Stricture

Current therapeutic modalities to treat urethral strictures are associated with several challenges and shortcomings. Therefore, significant strides have been made to develop strategies with minimal side effects and the highest therapeutic potential. In this framework, electrospun scaffolds incorporated with various cells or bioactive agents have provided promising vistas to repair urethral defects. Due to the biomimetic nature of these constructs, they can efficiently mimic the native cells’ niches and provide essential microenvironmental cues for the safe transplantation of multiple cell types. Furthermore, these scaffolds are versatile platforms for delivering various drug molecules, growth factors, and nucleic acids. This review discusses the recent progress, applications, and challenges of electrospun scaffolds to deliver cells or bioactive agents during the urethral defect repair process. First, the current status of electrospinning in urethral tissue engineering is presented. Then, the principles of electrospinning in drug and cell delivery applications are reviewed. Finally, the recent preclinical studies are summarized and the current challenges are discussed.

Extracellular Vesicles for Regenerative Medicine Applications

Tissue engineering and regenerative medicine (TERM) may be defined as a translational discipline focused on the development of novel techniques, devices, and materials to replace or repair injured or diseased tissue and organs. The main approaches typically use cells, scaffolds, and signaling molecules, either alone or in combination, to promote repair and regeneration. Although cells are required to create new functional tissue, the source of cells, either from an exogenous allogeneic or autologous source or through the recruitment of endogenous (autologous) cells, is technically challenging and risks the host rejection of new tissue. Regardless of the cell source, these approaches also require appropriate instruction for proliferation, differentiation, and in vivo spatial organization to create new functional tissue. Such instruction is supplied through the microenvironment where cells reside, environments which largely consist of the extracellular matrix (ECM). The specific components of the ECM, and broadly the extracellular space, responsible for promoting tissue regeneration and repair, are not fully understood, however extracellular vesicles (EVs) found in body fluids and solid phases of ECM have emerged as key mediators of tissue regeneration and repair. Additionally, these EVs might serve as potential cell-free tools in TERM to promote tissue repair and regeneration with minimal risk for host rejection and adverse sequelae. The past two decades have shown a substantial interest in understanding the therapeutic role of EVs and their applications in the context of TERM. Therefore, the purpose of this review is to highlight the fundamental characteristics of EVs, the current pre-clinical and clinical applications of EVs in TERM, and the future of EV-based strategies in TERM.

Cell Secretome Strategies for Controlled Drug Delivery and Wound-Healing Applications

There is significant interest in using stem cells in the management of cutaneous wounds. However, potential safety, efficacy, and cost problems associated with whole-cell transplantation hinder their clinical application. Secretome, a collective of mesenchymal stem-cell-stored paracrine factors, and immunomodulatory cytokines offer therapeutic potential as a cell-free therapy for the treatment of cutaneous wounds. This review explores the possibility of secretome as a treatment for cutaneous wounds and tissue regeneration. The review mainly focuses on in vitro and in vivo investigations that use biomaterials and secretome together to treat wounds, extend secretome retention, and control release to preserve their biological function. The approaches employed for the fabrication of biomaterials with condition media or extracellular vesicles are discussed to identify their future clinical application in wound treatment.