Exosomes Secreted by Human-Induced Pluripotent Stem Cell-Derived Mesenchymal Stem Cells Repair Critical-Sized Bone Defects through Enhanced Angiogenesis and Osteogenesis in Osteoporotic Rats

Novel Strategies for Angiogenesis in Tissue Injury: Therapeutic Effects of iPSCs-Derived Exosomes

Regeneration after tissue injury is a dynamic and complex process, and angiogenesis is necessary for normal physiological activities and tissue repair. Induced pluripotent stem cells are a new approach in regenerative medicine, which provides good model for the study of difficult-to-obtain human tissues, patient-specific therapy, and tissue repair. As an innovative cell-free therapeutic strategy, the main advantages of the treatment of induced pluripotent stem cells (iPSCs)-derived exosomes are low in tumorigenicity and immunogenicity, which become an important pathway for tissue injury. This review focuses on the mechanism of the angiogenic effect of iPSCs-derived exosomes on wound repair in tissue injury and their potential therapeutic targets, with a view to providing a theoretical basis for the use of iPSCs-derived exosomes in clinical therapy.

Intra-articular injection of exosomes derived from different stem cells in animal models of osteoarthritis: a systematic review and meta- analysis

BACKGROUND

In recent years, the increasing incidence of osteoarthritis (OA) has attracted widespread public attention; however, the available effective treatments are limited. As a result, new therapeutic approaches, including stem cell and exosome therapies, have been proposed and are gradually gaining popularity. Because exosomes are immunocompatible, there is thought to be more potential for their use in clinical settings. This study summarizes the efficacy of exosomes in the treatment of OA.

METHODS

In total, we conducted a comprehensive search of the PubMed, Web of Science, and Embase databases using medical subject headings terms to identify studies published from their inception until November 2023 that investigated the use of stem cell-derived exosomes in treating OA. We focused on specific outcomes including osteophyte score, chondrocyte count, pain level, qPCR and histological assessments such as the OARSI (Osteoarthritis research society international) score to measure cartilage degeneration. For data extraction, we used GetData Graph Digitizer to retrieve values from graphs, and the meta-analysis was conducted using RevMan 5.3 software. We chose mean difference (MD) as the primary effect measure since all included studies reported the same outcomes. Ultimately, 20 articles met the inclusion criteria and were included in the meta-analysis.

RESULTS

We evaluated 20 studies comprising a total of 400 subjects. Compared with control groups, the exosome-treated groups showed significantly improved histological outcomes, as measured by the OARSI score (n = 400; MD = -3.54; 95% CI = [-4.30, -2.79]; P < 0.00001; I2 = 98%). This indicates a marked reduction in cartilage degeneration and OA severity in the exosome-treated groups. Notably, exosome therapy was more effective when administered during the early stages of OA. Additionally, a once-weekly dosing schedule yielded better results compared to more frequent administrations. Of the three exosome isolation methods assessed, kit-based extraction demonstrated a trend toward superior therapeutic efficacy.

CONCLUSIONS

Exosome treatment improved OA compared to placebo treatment.

Extracellular derivatives for bone metabolism

BACKGROUND

Bone metabolism can maintain the normal homeostasis and function of bone tissue. Once the bone metabolism balance is broken, it will cause osteoporosis, osteoarthritis, bone defects, bone tumors, or other bone diseases. However, such orthopedic diseases still have many limitations in clinical treatment, such as drug restrictions, drug tolerance, drug side effects, and implant rejection.

AIM OF REVIEW

In complex bone therapy and bone regeneration, extracellular derivatives have become a promising research focus to solve the problems of bone metabolic diseases. These derivatives, which include components such as extracellular matrix, growth factors, and extracellular vesicles, have significant therapeutic potential. It has the advantages of good biocompatibility, low immune response, and dynamic demand for bone tissue. The purpose of this review is to provide a comprehensive perspective on extracellular derivatives for bone metabolism and elucidate the intrinsic properties and versatility of extracellular derivatives. Further discussion of them as innovative advanced orthopedic materials for improving the effectiveness of bone therapy and regeneration processes.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, we first listed the types and functions of three extracellular derivatives. Then, we discussed the effects of extracellular derivatives of different cell sources on bone metabolism. Subsequently, we collected applications of extracellular derivatives in the treatment of bone metabolic diseases and summarized the advantages and challenges of extracellular derivatives in clinical applications. Finally, we prospected the extracellular derivatives in novel orthopedic materials and clinical applications. We hope that the comprehensive understanding of extracellular derivatives in bone metabolism will provide new solutions to bone diseases.

Biologic therapies in stress fractures: Current concepts

Stress fractures, a common overuse injury in physically active individuals, present a significant challenge for athletes and military personnel. Patients who sustain stress fractures have demanding training regimes where periods of rest and immobilisation have unacceptable negative consequences on sports goals and finances. Aside from being an overuse injury, there are various contributing risk factors that put certain individuals at risk of a stress fracture. The main two being nutritional deficiencies and hormonal variations, which have significant effects on bone metabolism and turnover. Historically, treatment of stress fractures focused on conservative strategies such as rest and immobilisation. Calcium and vitamin D deficiencies have been closely linked to stress fractures and so over time supplementation has also played a role in treatment. With the introduction of biologics into orthopaedics, newer treatment strategies have been applied to accelerate fracture healing and perhaps improve fracture callus quality. If such therapies can reduce time spent away from sport and activity, it would be ideal for treating stress fractures. This article aims to offer insights into the evolving landscape of stress fracture management. It investigates the pre-clinical evidence and available published clinical applications. Though fracture healing is well understood, the role of biologics for fracture healing is still indeterminate. Available literature for the use of biologic therapies in stress fractures are restricted and most reports have used biologics as a supplement to surgical fixation in subjects in studies that lack control groups. Randomised control trials have been proposed and registered by a few groups, with results awaited. Assessing individuals for risk factors, addressing hormonal imbalances and nutritional deficiencies seems like an effective approach to addressing the burden of stress fractures. We await better designed trials and studies to accurately determine the clinical benefit of adding biologics to the management of these injuries.

The Influence of Extracellular Vesicles Secreted by Dural Cells on Osteoblasts

To explore the influence of extracellular vesicles secreted by dural cells (Dura-EVs) on osteoblasts. Our methodology involves assessing the effects of these EVs at concentrations of 50ug/ml, 100ug/ml, and 200ug/ml on osteoblasts proliferation, differentiation, migration, osteogenesis, and inhibition of apoptosis. We also treated a cranial defect model with injections of these Dura-EVs and monitored the healing rate of cranial defects. Tissue sections were analyzed using Hematoxylin and Eosin (H & E), Masson's trichrome, and immunofluorescence (IF) staining. Our results suggest that Dura-EVs can enhance osteoblasts proliferation, migration, differentiation, and osteogenesis in a dose-dependent manner in vitro. In vivo, Dura-EVs may promote the repair of skull defects. Dura-EVs have an important influence on osteoblasts, our findings shed light on a novel aspect of the dura mater's contribution to cranial osteogenesis.

The Opportunities and Challenges of Mesenchymal Stem Cells-Derived Exosomes in Theranostics and Regenerative Medicine

Cell-secreted nanovesicles of endosomal origin, called exosomes, are vital for mediating intracellular communication. As local or distal transporters of intracellular cargo, they reflect the unique characteristics of secretory cells and establish cell-specific interactions via characteristic surface proteins and receptors. With the advent of rapid isolation, purification, and identification techniques, exosomes have become an attractive choice for disease diagnosis (exosomal content as biomarkers), cell-free therapy, and tissue regeneration. Mesenchymal stem cell (MSC)-derived exosomes (MSC-exosomes) display angiogenic, immune-modulatory, and other therapeutic effects crucial for cytoprotection, ischemic wound repair, myocardial regeneration, etc. The primary focus of this review is to highlight the widespread application of MSC-exosomes in therapeutics, theranostics, and tissue regeneration. After a brief introduction of exosome properties, biogenesis, isolation, and functions, recent studies on therapeutic and regenerative applications of MSC-exosomes are described, focusing on bone, cartilage, periodontal, cardiovascular, skin, and nerve regeneration. Finally, the review highlights the theranostic potential of exosomes followed by challenges, summary, and outlook.

Exosome-Integrated Hydrogels for Bone Tissue Engineering

Exosome-integrated hydrogels represent a promising frontier in bone tissue engineering, leveraging the unique biological properties of exosomes to enhance the regenerative capabilities of hydrogels. Exosomes, as naturally occurring extracellular vesicles, carry a diverse array of bioactive molecules that play critical roles in intercellular communication and tissue regeneration. When combined with hydrogels, these exosomes can be spatiotemporally delivered to target sites, offering a controlled and sustained release of therapeutic agents. This review aims to provide a comprehensive overview of the recent advancements in the development, engineering, and application of exosome-integrated hydrogels for bone tissue engineering, highlighting their potential to overcome current challenges in tissue regeneration. Furthermore, the review explores the mechanistic pathways by which exosomes embedded within hydrogels facilitate bone repair, encompassing the regulation of inflammatory pathways, enhancement of angiogenic processes, and induction of osteogenic differentiation. Finally, the review addresses the existing challenges, such as scalability, reproducibility, and regulatory considerations, while also suggesting future directions for research in this rapidly evolving field. Thus, we hope this review contributes to advancing the development of next-generation biomaterials that synergistically integrate exosome and hydrogel technologies, thereby enhancing the efficacy of bone tissue regeneration.

BMSC-derived exosomes promote osteoporosis alleviation via M2 macrophage polarization

Osteoporosis is characterized by reduced bone mass due to imbalanced bone metabolism. Exosomes derived from bone mesenchymal stem cells (BMSCs) have been shown to play roles in various diseases. This study aimed to clarify the regulatory function and molecular mechanism of BMSCs-derived exosomes in osteogenic differentiation and their potential therapeutic effects on osteoporosis. Exosomes were extracted from BMSCs. Bone marrow-derived macrophages (BMDMs) were cultured and internalized with BMSCs-derived exosomes. Real-time quantitative PCR was used to detect the expression of macrophage surface markers and tripartite motif (TRIM) family genes. BMDMs were co-cultured with human osteoblasts to assess osteogenic differentiation. Western blot was performed to analyze the ubiquitination of triggering receptor expressed on myeloid cell 1 (TREM1) mediated by TRIM25. An ovariectomized mice model was established to evaluate the role of TRIM25 and exosomes in osteoporosis. Exosomes were successfully isolated from BMSCs. BMSCs-derived exosomes upregulated TRIM25 expression, promoting M2 macrophage polarization and osteogenic differentiation. TRIM25 facilitated the ubiquitination and degradation of TREM1. Overexpression of TREM1 reversed the enhanced M2 macrophage polarization and osteogenic differentiation caused by TRIM25 overexpression. TRIM25 enhanced the protective effect of BMSCs-derived exosomes against bone loss in mice. These findings suggested that BMSCs-derived exosomes promoted osteogenic differentiation by regulating M2 macrophage polarization through TRIM25-mediated ubiquitination and degradation of TREM1. This mechanism might provide a novel approach for treating osteoporosis.

Prolonged cultivation enhances the stimulatory activity of hiPSC mesenchymal progenitor-derived conditioned medium

BACKGROUND

Human induced pluripotent stem cells represent a scalable source of youthful tissue progenitors and secretomes for regenerative therapies. The aim of our study was to investigate the potential of conditioned medium (CM) from hiPSC-mesenchymal progenitors (hiPSC-MPs) to stimulate osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells (MSCs). We also investigated whether prolonged cultivation or osteogenic pre-differentiation of hiPSC-MPs could enhance the stimulatory activity of CM.

METHODS

MSCs were isolated from 13 donors (age 20-90 years). CM derived from hiPSC-MPs was added to the MSC cultures and the effects on proliferation and osteogenic differentiation were examined after 14 days and 6 weeks. The stimulatory activity of hiPSC-MP-CM was compared with the activity of MSC-derived CM and with the activity of CM prepared from hiPSC-MPs pre-cultured in growth or osteogenic medium for 14 days. Comparative proteomic analysis of CM was performed to gain insight into the molecular components responsible for the stimulatory activity.

RESULTS

Primary bone marrow-derived MSC exhibited variability, with a tendency towards lower proliferation and tri-lineage differentiation in older donors. hiPSC-MP-CM increased the proliferation and alkaline phosphatase activity of MSC from several adult/aged donors after 14 days of continuous supplementation under osteogenic conditions. However, CM supplementation failed to improve the mineralization of MSC pellets after 6 weeks under osteogenic conditions. hiPSC-MP-CM showed greater enhancement of proliferation and ALP activity than CM derived from bone marrow-derived MSCs. Moreover, 14-day cultivation but not osteogenic pre-differentiation of hiPSC-MPs strongly enhanced CM stimulatory activity. Quantitative proteomic analysis of d14-CM revealed a distinct profile of components that formed a highly interconnected associations network with two clusters, one functionally associated with binding and organization of actin/cytoskeletal components and the other with structural constituents of the extracellular matrix, collagen, and growth factor binding. Several hub proteins were identified that were reported to have functions in cell-extracellular matrix interaction, osteogenic differentiation and development.

CONCLUSIONS

Our data show that hiPSC-MP-CM enhances early osteogenic differentiation of human bone marrow-derived MSCs and that prolonged cultivation of hiPSC-MPs enhances CM-stimulatory activity. Proteomic analysis of the upregulated protein components provides the basis for further optimization of hiPSC-MP-CM for bone regenerative therapies.

Mesoporous bioactive glass-enhanced MSC-derived exosomes promote bone regeneration and immunomodulation in vitro and in vivo

Background

Exosomes produced by mesenchymal stem cells (MSCs) have vascular generative properties and are considered new effective candidates for the treatment of bone defects as alternatives to cell therapy. Improving the pro-regenerative function and efficacy of exosomes has been a popular research topic in the field of orthopaedics.

Methods

We prepared mesoporous bioactive glass (mBG) microspheres via the template method. The ionic products of mBGs used to treat MSCs were extracted, and the effects of exosomes secreted by MSCs on osteoblast (OB) and macrophage (MP) behaviour and bone defect repair were observed in vivo (Micro-CT, H&E, Masson, and immunofluorescence staining for BMP2, COL1, VEGF, CD31, CD163, and iNOS).

Results

The mBG spheres were successfully prepared, and the Exo-mBG were isolated and extracted. Compared with those in the blank and Exo-Con groups, the proliferation and osteogenic differentiation of OBs in the Exo-mBG group were significantly greater. For example, on Day 7, OPN gene expression in the Ctrl-Exo group was 3.97 and 2.83 times greater than that in the blank and Exo-mBG groups, respectively. In a cranial defect rat model, Exo-mBG promoted bone tissue healing and angiogenesis, increased M2 macrophage polarisation and inhibited M1 macrophage polarisation, as verified by micro-CT, H&E staining, Masson staining and immunofluorescence staining. These effects may be due to the combination of a higher silicon concentration and a higher calcium-to-phosphorus ratio in the mBG ionic products.

Conclusion

This study provides insights for the application of exosomes in cell-free therapy and a new scientific basis and technical approach for the utilisation of MSC-derived exosomes in bone defect repair.

The translational potential of this article

Our study demonstrated that exosomes produced by mBG-stimulated MSCs have excellent in vitro and in vivo bone-enabling and immunomodulatory functions and provides insights into the use of exosomes in clinical cell-free therapies.

The impact of exosomes on bone health: A focus on osteoporosis

Osteoporosis is a widespread chronic condition. Although standard treatments are generally effective, they are frequently constrained by side effects and the risk of developing drug resistance. A promising area of research is the investigation of extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, which play a crucial role in bone metabolism. Exosomes, in particular, have shown significant potential in both the diagnosis and treatment of osteoporosis. EVs derived from osteoclasts, osteoblasts, mesenchymal stem cells, and other sources can influence bone metabolism, while exosomes from inflammatory and tumor cells may exacerbate bone loss, highlighting their dual role in osteoporosis pathology. This review offers a comprehensive overview of EV biogenesis, composition, and function in osteoporosis, focusing on their diagnostic and therapeutic potential. We examine the roles of various types of EVs and their cargo-proteins, RNAs, and lipids-in bone metabolism. Additionally, we explore the emerging applications of EVs as biomarkers and therapeutic agents, emphasizing the need for further research to address current challenges and enhance EV-based strategies for managing osteoporosis.

Current and emerging therapeutic strategies for perianal fistula in Crohn's disease patients

The long-term remission rates achieved with current treatment options for Crohn's disease with perianal fistula (CD-PAF)-including antibiotics, biologics, immunomodulators, and Janus kinase inhibitors, often combined with advanced surgical interventions-remain unsatisfactory. This chapter explores several innovative biomaterials-based solutions, such as plugs, adhesives, fillers, and stem cell-based therapies. The key approaches and treatment outcomes of these advanced therapies are examined, focusing on their ability to modulate the immune response, promote tissue healing, and improve patient outcomes. Additionally, the chapter discusses future directions, including the optimization of biomaterial designs, enhancement of delivery and retention of regenerative therapies, and a deeper understanding of the underlying mechanisms of healing.

Engineered extracellular vesicles for tissue repair and regeneration

Extracellular vesicles (EVs) are heterogeneous membrane-like vesicles secreted by living cells that are involved in many physiological and pathological processes and act as intermediaries of intercellular communication and molecular transfer. Recent studies have shown that EVs from specific sources regulate tissue repair and regeneration by delivering proteins, lipids, and nucleic acids to target cells as signaling molecules. Nanotechnology breakthroughs have facilitated the development and exploration of engineered EVs for tissue repair. Enhancements through gene editing, surface modification, and content modification have further improved their therapeutic efficacy. This review summarizes the potential of EVs in tissue repair and regeneration, their mechanisms of action, and their research progress in regenerative medicine. This review highlights their design logic through typical examples and explores the development prospects of EVs in tissue repair. The aim of this review is to provide new insights into the design of EVs for tissue repair and regeneration applications, thereby expanding their use in regenerative medicine.

Unveiling the Immunomodulatory and regenerative potential of iPSC-derived mesenchymal stromal cells and their extracellular vesicles

Induced pluripotent stem cell (iPSC)-derived mesenchymal stromal cells (iMSCs) offer a promising alternative to primary mesenchymal stromal cells (MSCs) and their derivatives, particularly extracellular vesicles (EVs), for use in advanced therapy medicinal products. In this study we evaluated the immunomodulatory and regenerative potential of iMSCs as well as iMSC-EVs, alongside primary human umbilical cord-derived mesenchymal stromal cells (hUCMSCs). Our findings demonstrate that iMSCs exhibit comparable abilities to hUCMSCs in regulating lymphocyte proliferation and inducing an anti-inflammatory phenotype in monocytes. We also observed decreased TNFα levels and increased IL-10 induction, indicating a potential mechanism for their immunomodulatory effects. Furthermore, iMSC-EVs also showed effective immunomodulation by inhibiting T cell proliferation and inducing macrophage polarization similar to their parental cells. Additionally, iMSC-EVs exhibited pro-regenerative potential akin to hUCMSC-EVs in in vitro scratch assays. Notably, priming iMSCs with pro-inflammatory cytokines significantly enhanced the immunomodulatory potential of iMSC-EVs. These results underscore the considerable promise of iMSCs and iMSCs-EVs as an alternate source for MSC-derived therapeutics, given their potent immunomodulatory and regenerative properties.

Mesenchymal stem cell-derived exosomes: a potential cell-free therapy for orthodontic tooth stability management

Orthodontic relapse (OR) occurs at a rate of over 70%. Retention is the current attempt at prevention, but it requires a considerable amount of time and cannot fully block OR. It's imperative to find a safe and effective method for managing post-orthodontic tooth stability. Periodontal bone remodeling is one crucial biological foundation of OR. Mesenchymal stem cell-derived exosomes (MSC-Exo) show promise in relapse management by regulating periodontal bone remodeling. MSC-Exo can prevent relapse by regulating periodontal ligament function, osteoclast activity, osteoblast differentiation, macrophage polarization, and periodontal microcirculation. In recent years, exosome-loaded hydrogels, which achieve controlled exosome release, have demonstrated efficacy in promoting bone regeneration and remodeling, offering promising prospects for OR management. This review aims to highlight the use of MSC-Exo-based therapy for preventing OR, offering new insights for future research focused on improving tooth stability and enhancing orthodontic anchorage.

Recent trends of stem cell therapies in the management of orthopedic surgical challenges

Emerged health-related problems especially with increasing population and with the wider occurrence of these issues have always put the utmost concern and led medicine to outgrow its usual mode of treatment, to achieve better outcomes. Orthopedic interventions are one of the most concerning hitches, requiring advancement in several issues, that show complications with conventional approaches. Advanced studies have been undertaken to address the issue, among which stem cell therapy emerged as a better area of growth. The capacity of the stem cells to renovate themselves and adapt into different cell types made it possible to implement its use as a regenerative slant. Harvesting the stem cells, particularly mesenchymal stem cells (MSCs) is easier and can be further grown in vitro . In this review, we have discussed orthopedic-related issues including bone defects and fractures, nonunions, ligament and tendon injuries, degenerative changes, and associated conditions, which require further approaches to execute better outcomes, and the advanced strategies that can be tagged along with various ways of application of MSCs. It aims to objectify the idea of stem cells, with a major focus on the application of MSCs from different sources in various orthopedic interventions. It also discusses the limitations, and future scopes for further approaches in the field of regenerative medicine. The involvement of MSCs may transition the procedures in orthopedic interventions from predominantly surgical substitution and reconstruction to bio-regeneration and prevention. Nevertheless, additional improvements and evaluations are required to explore the effectiveness and safety of mesenchymal stem cell treatment in orthopedic regenerative medicine.

Stem Cells in Bone Tissue Engineering: Progress, Promises and Challenges

Bone defects from accidents, congenital conditions, and age-related diseases significantly impact quality of life. Recent advancements in bone tissue engineering (TE) involve biomaterial scaffolds, patient-derived cells, and bioactive agents, enabling functional bone regeneration. Stem cells, obtained from numerous sources including umbilical cord blood, adipose tissue, bone marrow, and dental pulp, hold immense potential in bone TE. Induced pluripotent stem cells and genetically modified stem cells can also be used. Proper manipulation of physical, chemical, and biological stimulation is crucial for their proliferation, maintenance, and differentiation. Stem cells contribute to osteogenesis, osteoinduction, angiogenesis, and mineralization, essential for bone regeneration. This review provides an overview of the latest developments in stem cell-based TE for repairing and regenerating defective bones.

Engineered mesenchymal stem cell-derived extracellular vesicles: kill tumors and protect organs

Solid tumors cause 90% of cancers and remain the primary cause of mortality. However, treating solid tumors presents significant challenges due to the complex tumor microenvironment and drug resistance, leading to inadequate treatment targeting and severe side effects. Surgery, radiotherapy, and chemotherapy Although it is an effective method for the treatment of solid tumors, it can lead to organ dysfunction and affect patient prognosis. Therefore, it is imperative to improve treatment precision and organ repair capabilities to manage solid tumors. Mesenchymal stem cell extracellular vesicles (MSC-EVs) have wide application prospects as a new agent for solid tumor therapy. Firstly, MSC-EVs is a derivative of MSCs. It has the function of promoting tissue regeneration by inducing dedifferentiation in surviving cells after injury. Additionally, MSC-EVs offer unique advantages in terms of safety, stability and penetrability, making them a promising extracellular therapeutic modality for solid tumor treatment. Finally, MSC-EVs are able to enhance therapeutic efficacy through engineering strategies. To sum up, this review takes MSC-EVs as its object. And then we discuss recent advancements and engineering strategies in the use of MSC-EVs for soid tumor suppression. This review aims to inspire researchers to devise a new method for effectively treat solid tumors.

Extracellular Vesicles Delivered by a Nanofiber-Hydrogel Composite Enhance Healing In Vivo in a Model of Crohn's Disease Perianal Fistula

Perianal fistulas represent a common, aggressive, and disabling complication of Crohn's disease (CD). Despite recent drug developments, novel surgical interventions as well as multidisciplinary treatment approaches, the outcome is dismal, with >50% therapy failure rates. Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) offer potential therapeutic benefits for treating fistulizing CD, due to the pro-regenerative paracrine signals. However, a significant obstacle to clinical translation of EV-based therapy is the rapid clearance and short half-life of EVs in vivo. Here, an injectable, biodegradable nanofiber-hydrogel composite (NHC) microgel matrix that serves as a carrier to deliver MSC-derived EVs to a rat model of CD perianal fistula (PAF) is reported. It is found that EV-loaded NHC (EV-NHC) yields the best fistula healing when compared to other treatment arms. The MRI assessment reveals that the EV-NHC reduces inflammation at the fistula site and promotes tissue healing. The enhanced therapeutic outcomes are contributed by extended local retention and sustained release of EVs by NHC. In addition, the EV-NHC effectively reduces inflammation at the fistula site and promotes tissue healing and regeneration via macrophage polarization and neo-vascularization. This EV-NHC platform provides an off-the-shelf solution that facilitates its clinical translation.

The Role of Extracellular Vesicles in Bone Regeneration and Associated Bone Diseases

Extracellular vesicles (EVs) are nanoscale particles with a lipid bilayer membrane structure secreted by various cell types. Nearly all human cells secrete EVs, primarily mediating intercellular communication. In recent years, scientists have discovered that EVs can carry multiple biological cargos, such as DNA, non-coding RNAs (ncRNAs), proteins, cytokines, and lipids, and mediate intercellular signal transduction. Bone is a connective tissue with a nerve supply and high vascularization. The repair process after injury is highly complex, involving interactions among multiple cell types and biological signaling pathways. Bone regeneration consists of a series of coordinated osteoconductive and osteoinductive biological processes. As mediators of intercellular communication, EVs can promote bone regeneration by regulating osteoblast-mediated bone formation, osteoclast-mediated bone resorption, and other pathways. This review summarizes the biogenesis of EVs and the mechanisms by which EV-mediated intercellular communication promotes bone regeneration. Additionally, we focus on the research progress of EVs in various diseases related to bone regeneration. Finally, based on the above research, we explore the clinical applications of engineered EVs in the diagnosis and treatment of bone regeneration-related diseases.

Targeting miR-29 mitigates skeletal senescence and bolsters therapeutic potential of mesenchymal stromal cells

Mesenchymal stromal cell (MSC) senescence is a key factor in skeletal aging, affecting the potential of MSC applications. Identifying targets to prevent MSC and skeletal senescence is crucial. Here, we report increased miR-29 expression in bone tissues of aged mice, osteoporotic patients, and senescent MSCs. Genetic overexpression of miR-29 in Prx1-positive MSCs significantly accelerates skeletal senescence, reducing cortical bone thickness and trabecular bone mass, while increasing femur cross-sectional area, bone marrow adiposity, p53, and senescence-associated secretory phenotype (SASP) levels. Mechanistically, miR-29 promotes senescence by upregulating p53 via targeting Kindlin-2 mRNA. miR-29 knockdown in BMSCs impedes skeletal senescence, enhances bone mass, and accelerates calvarial defect regeneration, also reducing lipopolysaccharide (LPS)-induced organ injuries and mortality. Thus, our findings underscore miR-29 as a promising therapeutic target for senescence-related skeletal diseases and acute inflammation-induced organ damage.

Effects of human umbilical cord mesenchymal stem cell-derived exosomes in the rat osteoarthritis models

Mesenchymal stem cells (MSCs) offer great potential for treatment of osteoarthritis (OA) by promoting articular cartilage regeneration via paracrine secretion of exosomes; however, the underlying mechanisms are not fully understood. This study aimed to explore the therapeutic effects of exosomes secreted by human umbilical cord-derived MSCs (hUC-MSCs) in rat models of OA and reveal the underlying mechanisms. UC-MSCs and UC-MSC-exosomes were prepared and identified by transmission electron microscopy and flow cytometry. IL-1β-induced OA chondrocytes and the operation and collagenase-induced OA rat models were established. The results of micro-computed tomography, histology, and immunohistochemistry showed that UC-MSC-exosomes promoted cartilage regeneration in OA rats. ELISA results showed that the levels of synovial fluid cytokines, TNF-α, IL-1β, and IL-6, were lower in exosome therapy group than control group in both OA rat models. Exosome treatment significantly downregulated the expression of MMP-13 and ADAMTS-5 in chondrocytes stimulated by IL-1β, and upregulated collagen II expression. These findings suggest that hUC-MSC-exosomes offer a promising option for the therapy for OA.

The application potential of iMSCs and iMSC-EVs in diseases

The immune system, functioning as the body's "defense army", plays a role in surveillance, defense. Any disruptions in immune system can lead to the development of immune-related diseases. Extensive researches have demonstrated the crucial immunoregulatory role of mesenchymal stem cells (MSCs) in these diseases. Of particular interest is the ability to induce somatic cells under specific conditions, generating a new cell type with stem cell characteristics known as induced pluripotent stem cell (iPSC). The differentiation of iPSCs into MSCs, specifically induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs), hold promise as a potential solution to the challenges of MSCs, potentially serving as an alternative to traditional drug therapies. Moreover, the products of iMSCs, termed induced pluripotent stem cell-derived mesenchymal stem cell-derived extracellular vesicles (iMSC-EVs), may exhibit functions similar to iMSCs. With the biological advantages of EVs, they have become the focus of "cell-free therapy". Here, we provided a comprehensive summary of the biological impact of iMSCs on immune cells, explored the applications of iMSCs and iMSC-EVs in diseases, and briefly discussed the fundamental characteristics of EVs. Finally, we overviewed the current advantages and challenges associated with iMSCs and iMSC-EVs. It is our hope that this review related to iMSCs and iMSC-EVs will contribute to the development of new approaches for the treatment of diseases.

Exosome-loaded hydrogels for craniofacial bone tissue regeneration

It is common for maladies and trauma to cause significant bone deterioration in the craniofacial bone, which can cause patients to experience complications with their appearance and their ability to function. Regarding grafting procedures' complications and disadvantages, the newly emerging field of tissue regeneration has shown promise. Tissue -engineered technologies and their applications in the craniofacial region are increasingly gaining prominence with limited postoperative risk and cost. MSCs-derived exosomes are widely applied in bone tissue engineering to provide cell-free therapies since they not only do not cause immunological rejection in the same way that cells do, but they can also perform a cell-like role. Additionally, the hydrogel system is a family of multipurpose platforms made of cross-linked polymers with considerable water content, outstanding biocompatibility, and tunable physiochemical properties for the efficient delivery of commodities. Therefore, the promising exosome-loaded hydrogels can be designed for craniofacial bone regeneration. This review lists the packaging techniques for exosomes and hydrogel and discusses the development of a biocompatible hydrogel system and its potential for exosome continuous delivery for craniofacial bone healing.

Global scientific trends on exosomes therapy for osteoporosis from 2004 to 2023: A bibliometric and visualized analysis

BACKGROUND

Exosomes have emerged as pivotal mediators in modulating physiological and pathological processes implicated in osteoporosis (OP) through their distinctive mode of intracellular communication. The use of exosomes has evoked considerable interest, catalyzing a surge in research endeavors on a global scale. This study endeavors to scrutinize contemporary landscapes and burgeoning trends in this realm.

METHODS

The Web of Science Core Collection was used to retrieve publications on exosomes therapy for OP within the time frame of January 1, 2004 to December 31, 2023. The bibliometric methodology was applied to study and index the collected data. VOSviewer and citespace software were used to conduct visualization, co-authorship, co-occurrence, and publication trend analyses of exosome therapy in OP.

RESULTS

A total of 610 publications (443 articles and 167 reviews) from 51 countries and 911 institutions were included in this study. Shanghai Jiao Tong University, Central South University, Sichuan University, and Zhejiang University are leading research institutions in this field. Stem Cell Research Therapy published the highest number of articles and has emerged as the most cited journal. Of the 4077 scholars who participated in the study, Xie, Hui, Zhang, Yan, Tan, and Yi-Juan had the largest number of articles. Furthermore, according to the cluster analysis of external keywords, future research hotspots can be categorized into 3 directions: research status of exosomes for the treatment of OP, treatment of OP through exosome-regulated signaling pathways, and exosomes as targeted drug delivery systems.

CONCLUSION

This study suggests that the number of future publications on exosome therapy for OP will increase, with a focus on fundamental investigations into drug-loading capacities and molecular mechanisms. In summary, this study presents the first systematic bibliometric analysis of exosome therapy publications in OP, providing an objective and comprehensive overview of the field and a valuable reference for researchers in this domain.

Engineering extracellular vesicles for ROS scavenging and tissue regeneration

Stem cell therapy holds promise for tissue regeneration, yet significant challenges persist. Emerging as a safer and potentially more effective alternative, extracellular vesicles (EVs) derived from stem cells exhibit remarkable abilities to activate critical signaling cascades, thereby facilitating tissue repair. EVs, nano-scale membrane vesicles, mediate intercellular communication by encapsulating a diverse cargo of proteins, lipids, and nucleic acids. Their therapeutic potential lies in delivering cargos, activating signaling pathways, and efficiently mitigating oxidative stress-an essential aspect of overcoming limitations in stem cell-based tissue repair. This review focuses on engineering and applying EVs in tissue regeneration, emphasizing their role in regulating reactive oxygen species (ROS) pathways. Additionally, we explore strategies to enhance EV therapeutic activity, including functionalization and incorporation of antioxidant defense proteins. Understanding these molecular mechanisms is crucial for optimizing EV-based regenerative therapies. Insights into EV and ROS signaling modulation pave the way for targeted and efficient regenerative therapies harnessing the potential of EVs.

Cold exposure-induced plasma exosomes impair bone mass by inhibiting autophagy

Recently, environmental temperature has been shown to regulate bone homeostasis. However, the mechanisms by which cold exposure affects bone mass remain unclear. In our present study, we observed that exposure to cold temperature (CT) decreased bone mass and quality in mice. Furthermore, a transplant of exosomes derived from the plasma of mice exposed to cold temperature (CT-EXO) can also impair the osteogenic differentiation of BMSCs and decrease bone mass by inhibiting autophagic activity. Rapamycin, a potent inducer of autophagy, can reverse cold exposure or CT-EXO-induced bone loss. Microarray sequencing revealed that cold exposure increases the miR-25-3p level in CT-EXO. Mechanistic studies showed that miR-25-3p can inhibit the osteogenic differentiation and autophagic activity of BMSCs. It is shown that inhibition of exosomes release or downregulation of miR-25-3p level can suppress CT-induced bone loss. This study identifies that CT-EXO mediates CT-induced osteoporotic effects through miR-25-3p by inhibiting autophagy via targeting SATB2, presenting a novel mechanism underlying the effect of cold temperature on bone mass.

Therapeutic potential of mesenchymal stem cell-derived exosomes in skeletal diseases

Skeletal diseases impose a considerable burden on society. The clinical and tissue-engineering therapies applied to alleviate such diseases frequently result in complications and are inadequately effective. Research has shifted from conventional therapies based on mesenchymal stem cells (MSCs) to exosomes derived from MSCs. Exosomes are natural nanocarriers of endogenous DNA, RNA, proteins, and lipids and have a low immune clearance rate and good barrier penetration and allow targeted delivery of therapeutics. MSC-derived exosomes (MSC-exosomes) have the characteristics of both MSCs and exosomes, and so they can have both immunosuppressive and tissue-regenerative effects. Despite advances in our knowledge of MSC-exosomes, their regulatory mechanisms and functionalities are unclear. Here we review the therapeutic potential of MSC-exosomes for skeletal diseases.

Harnessing GMNP-loaded BMSC-derived EVs to target miR-3064-5p via MEG3 overexpression: Implications for diabetic osteoporosis therapy in rats

Diabetic osteoporosis (DO) is a significant complication of diabetes, characterized by a decrease in bone mineral density and an increase in fracture risk. Magnetic nanoparticles (GMNPs) have emerged as potential drug carriers for various therapeutic applications. This study investigated the molecular mechanism of GMNPs loaded with bone marrow mesenchymal stem cell (BMSC) derived extracellular vesicles (EVs) overexpressing MEG3 target miR-3064-5p to induce NR4A3 for treating DO in rats. Initial analysis was carried out on GEO datasets GSE7158 and GSE62589, revealing a notable downregulation of NR4A3 in osteoporotic samples. Subsequent in vitro studies demonstrated the effective uptake of BMSC-EVs-MEG3 by osteoblasts and its potential to inhibit miR-3064-5p, activating the PINK1/Parkin signaling pathway and thus promoting mitochondrial autophagy, osteoblast proliferation, and differentiation. In vivo, experiments using DO rat models further substantiated the therapeutic efficacy of GMNPE-EVs-MEG3 in alleviating osteoporosis symptoms. In conclusion, GMNPs loaded with BMSC-EVs, through the delivery of MEG3 targeting miR-3064-5p, can effectively promote NR4A3 expression, activate the PINK1/Parkin pathway, and thereby enhance osteoblast proliferation and differentiation, offering a promising treatment for DO.

Extracellular vesicles in nanomedicine and regenerative medicine: A review over the last decade

Small extracellular vesicles (sEVs) are known to be secreted by a vast majority of cells. These sEVs, specifically exosomes, induce specific cell-to-cell interactions and can activate signaling pathways in recipient cells through fusion or interaction. These nanovesicles possess several desirable properties, making them ideal for regenerative medicine and nanomedicine applications. These properties include exceptional stability, biocompatibility, wide biodistribution, and minimal immunogenicity. However, the practical utilization of sEVs, particularly in clinical settings and at a large scale, is hindered by the expensive procedures required for their isolation, limited circulation lifetime, and suboptimal targeting capacity. Despite these challenges, sEVs have demonstrated a remarkable ability to accommodate various cargoes and have found extensive applications in the biomedical sciences. To overcome the limitations of sEVs and broaden their potential applications, researchers should strive to deepen their understanding of current isolation, loading, and characterization techniques. Additionally, acquiring fundamental knowledge about sEVs origins and employing state-of-the-art methodologies in nanomedicine and regenerative medicine can expand the sEVs research scope. This review provides a comprehensive overview of state-of-the-art exosome-based strategies in diverse nanomedicine domains, encompassing cancer therapy, immunotherapy, and biomarker applications. Furthermore, we emphasize the immense potential of exosomes in regenerative medicine.

A novel cell-free therapy using exosomes in the inner ear regeneration

Cellular and molecular alterations associated with hearing loss are now better understood with advances in molecular biology. These changes indicate the participation of distinct damage and stress pathways that are unlikely to be fully addressed by conventional pharmaceutical treatment. Sensorineural hearing loss is a common and debilitating condition for which comprehensive pharmacologic intervention is not available. The complex and diverse molecular pathology that underlies hearing loss currently limits our ability to intervene with small molecules. The present review focuses on the potential for the use of extracellular vesicles in otology. It examines a variety of inner ear diseases and hearing loss that may be treatable using exosomes (EXOs). The role of EXOs as carriers for the treatment of diseases related to the inner ear as well as EXOs as biomarkers for the recognition of diseases related to the ear is discussed.

Visualization Analysis of Small Extracellular Vesicles in the Application of Bone-Related Diseases

Small extracellular vesicles were shown to have similar functional roles to their parent cells without the defect of potential tumorigenicity, which made them a great candidate for regenerative medicine. The last twenty years have witnessed the rapid development of research on small extracellular vesicles. In this paper, we employed a scientometric synthesis method to conduct a retrospective analysis of small extracellular vesicles in the field of bone-related diseases. The overall background analysis consisted the visualization of the countries, institutions, journals, and authors involved in research. The current status of the research direction and future trends were presented through the analysis of references and keywords, which showed that engineering strategies, mesenchymal stem cell derived exosomes, and cartilage damage were the most concerning topics, and scaffold, osteoarthritis, platelet-rich plasma, and senescence were the future trends. We also discussed the current problems and challenges in practical applications, including the in-sight mechanisms, the building of relevant animal models, and the problems in clinical trials. By using CiteSpace, VOSviewer, and Bibliometrix, the presented data avoided subjective selectivity and tendency well, which made the conclusion more reliable and comprehensive. We hope that the findings can provide new perspectives for researchers to understand the evolution of this field over time and to search for novel research directions.

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.

Prospects and challenges for the application of tissue engineering technologies in the treatment of bone infections

Osteomyelitis is a devastating disease caused by microbial infection in deep bone tissue. Its high recurrence rate and impaired restoration of bone deficiencies are major challenges in treatment. Microbes have evolved numerous mechanisms to effectively evade host intrinsic and adaptive immune attacks to persistently localize in the host, such as drug-resistant bacteria, biofilms, persister cells, intracellular bacteria, and small colony variants (SCVs). Moreover, microbial-mediated dysregulation of the bone immune microenvironment impedes the bone regeneration process, leading to impaired bone defect repair. Despite advances in surgical strategies and drug applications for the treatment of bone infections within the last decade, challenges remain in clinical management. The development and application of tissue engineering materials have provided new strategies for the treatment of bone infections, but a comprehensive review of their research progress is lacking. This review discusses the critical pathogenic mechanisms of microbes in the skeletal system and their immunomodulatory effects on bone regeneration, and highlights the prospects and challenges for the application of tissue engineering technologies in the treatment of bone infections. It will inform the development and translation of antimicrobial and bone repair tissue engineering materials for the management of bone infections.

Effect of human periodontal ligament stem cell-derived exosomes on cementoblast activity

OBJECTIVES

Exosomes derived from stem cells are a potential cell-free tool for tissue regeneration with therapeutic potential. However, its application in cementum repair is unclear. This study aimed to investigate the effect of human periodontal ligament stem cell-derived exosomes on the biological activity of cementoblasts, the main effector cells in cementum synthesis.

MATERIALS AND METHODS

OCCM-30 cementoblasts were cultured with various human periodontal ligament stem cell-derived exosome concentrations. OCCM-30 cells proliferation, migration, and cementogenic mineralization were examined, along with the gene and protein expression of factors associated with cementoblastic mineralization.

RESULTS

Exosomal promoted the migration, proliferation, and mineralization of OCCM-30 cells. The exosome-treated group significantly increased the expression of cementogenic-related genes and proteins. Furthermore, the expression of p-PI3K and p-AKT was enhanced by exosome administration. Treatment with a PI3K/AKT inhibitor markedly attenuated the gene and protein expression of cementoblastic factors, and this effect was partially reversed by exosome administration.

CONCLUSIONS

Human periodontal ligament stem cell-derived exosomes can promote the activity of cementoblasts via the PI3K/AKT signaling pathway, providing a scientific basis for promoting the repair process in orthodontically induced inflammatory root resorption.

Vascular endothelial cells-derived exosomes synergize with curcumin to prevent osteoporosis development

Osteoporosis has gradually become a major public health problem. Further elucidation of the pathophysiological mechanisms that induce osteoporosis and identification of more effective therapeutic targets will have important clinical significance. Experiments in vitro on bone marrow stem cells (BMSCs) subjected to osteogenic and adipogenic differentiation and in vivo on surgical bilateral ovariectomy (OVX) mouse models revealed that exosomes of vascular endothelial cells (EC-EXOs) can promote osteogenic differentiation of BMSCs and inhibit BMSC adipogenic differentiation through miR-3p-975_4191. Both miR-3p-975_4191 and curcumin can target tumor necrosis factor (TNF) and act synergistically to regulate BMSCs fate differentiation and delay the progression of osteoporosis. Our findings suggest that EC-EXOs may exert a synergistic effect with curcumin in reversing the progression of osteoporosis by targeting TNF via miR-3p-975_4191. Our study may provide therapeutic options and potential therapeutic targets for osteoporosis and thus has important clinical implications.

Unlocking the potential of exosomes: a breakthrough in the theranosis of degenerative orthopaedic diseases

Degenerative orthopaedic diseases pose a notable worldwide public health issue attributable to the global aging population. Conventional medical approaches, encompassing physical therapy, pharmaceutical interventions, and surgical methods, face obstacles in halting or reversing the degenerative process. In recent times, exosome-based therapy has gained widespread acceptance and popularity as an effective treatment for degenerative orthopaedic diseases. This therapeutic approach holds the potential for "cell-free" tissue regeneration. Exosomes, membranous vesicles resulting from the fusion of intracellular multivesicles with the cell membrane, are released into the extracellular matrix. Addressing challenges such as the rapid elimination of natural exosomes in vivo and the limitation of drug concentration can be effectively achieved through various strategies, including engineering modification, gene overexpression modification, and biomaterial binding. This review provides a concise overview of the source, classification, and preparation methods of exosomes, followed by an in-depth analysis of their functions and potential applications. Furthermore, the review explores various strategies for utilizing exosomes in the treatment of degenerative orthopaedic diseases, encompassing engineering modification, gene overexpression, and biomaterial binding. The primary objective is to provide a fresh viewpoint on the utilization of exosomes in addressing bone degenerative conditions and to support the practical application of exosomes in the theranosis of degenerative orthopaedic diseases.

Mesenchymal Stem Cell-Derived Extracellular Vesicles in Bone-Related Diseases: Intercellular Communication Messengers and Therapeutic Engineering Protagonists

Extracellular vesicles (EVs) can deliver various bioactive molecules among cells, making them promising diagnostic and therapeutic alternatives in diseases. Mesenchymal stem cell-derived EVs (MSC-EVs) have shown therapeutic potential similar to MSCs but with drawbacks such as lower yield, reduced biological activities, off-target effects, and shorter half-lives. Improving strategies utilizing biotechniques to pretreat MSCs and enhance the properties of released EVs, as well as modifying MSC-EVs to enhance targeting abilities and achieve controlled release, shows potential for overcoming application limitations and enhancing therapeutic effects in treating bone-related diseases. This review focuses on recent advances in functionalizing MSC-EVs to treat bone-related diseases. Firstly, we underscore the significance of MSC-EVs in facilitating crosstalk between cells within the skeletal environment. Secondly, we highlight strategies of functional-modified EVs for treating bone-related diseases. We explore the pretreatment of stem cells using various biotechniques to enhance the properties of resulting EVs, as well as diverse approaches to modify MSC-EVs for targeted delivery and controlled release. Finally, we address the challenges and opportunities for further research on MSC-EVs in bone-related diseases.

Calcitonin gene-related peptide-modulated macrophage phenotypic alteration regulates angiogenesis in early bone healing

OBJECTIVES

This study aimed to investigate the effect of calcitonin gene-related peptide (CGRP) on the temporal alteration of macrophage phenotypes and macrophage-regulated angiogenesis duringearlybonehealing and preliminarily elucidate the mechanism.

METHODS

In vivo, the rat mandibular defect models were established with inferior alveolar nerve transection (IANT) or CGRP receptor antagonist injection. Radiographicandhistologic assessments for osteogenesis, angiogenesis, and macrophage phenotypic alteration within bone defects were performed. In vitro, the effect and mechanism of CGRP on macrophage polarization and phenotypic alteration were analyzed. Then the conditioned medium (CM) from CGRP-treated M1 or M2 macrophages was used to culture human umbilical vein endothelial cells (HUVECs), and the CGRP's effect on macrophage-regulated angiogenesis was detected.

RESULTS

Comparable changes following IANT and CGRP blockade within bone defects were observed, including the suppression of early osteogenesis and angiogenesis, the prolonged M1 macrophage infiltration and the prohibited transition toward M2 macrophages around vascular endothelium. In vitro experiments showed that CGRP promoted M2 macrophage polarization while upregulating the expression of interleukin 6 (IL-6), a major cytokine that facilitates the transition from M1 to M2-dominant stage, in M1 macrophages via the activation of Yes-associated protein 1. Moreover, CGRP-treated macrophage-CM showed an anabolic effect on HUVECs angiogenesis compared with macrophage-CM and might prevail over the direct effect of CGRP on HUVECs.

CONCLUSIONS

Collectively, our results reveal the effect of CGRP on M1 to M2 macrophage phenotypic alteration possibly via upregulating IL-6 in M1 macrophages, and demonstrate the macrophage-regulated pro-angiogenic potential of CGRP in early bone healing.

Functionalization of Ceramic Scaffolds with Exosomes from Bone Marrow Mesenchymal Stromal Cells for Bone Tissue Engineering

The functionalization of bone substitutes with exosomes appears to be a promising technique to enhance bone tissue formation. This study investigates the potential of exosomes derived from bone marrow mesenchymal stromal cells (BMSCs) to improve bone healing and bone augmentation when incorporated into wide open-porous 3D-printed ceramic Gyroid scaffolds. We demonstrated the multipotent characteristics of BMSCs and characterized the extracted exosomes using nanoparticle tracking analysis and proteomic profiling. Through cell culture experimentation, we demonstrated that BMSC-derived exosomes possess the ability to attract cells and significantly facilitate their differentiation into the osteogenic lineage. Furthermore, we observed that scaffold architecture influences exosome release kinetics, with Gyroid scaffolds exhibiting slower release rates compared to Lattice scaffolds. Nevertheless, in vivo implantation did not show increased bone ingrowth in scaffolds loaded with exosomes, suggesting that the scaffold microarchitecture and material were already optimized for osteoconduction and bone augmentation. These findings highlight the lack of understanding about the optimal delivery of exosomes for osteoconduction and bone augmentation by advanced ceramic scaffolds.

Nrf2 activation: a key mechanism in stem cell exosomes-mediated therapies

Exosomes are nano-sized membrane extracellular vesicles which can be released from various types of cells. Exosomes originating from inflammatory or injured cells can have detrimental effects on recipient cells, while exosomes derived from stem cells not only facilitate the repair and regeneration of damaged tissues but also inhibit inflammation and provide protective effects against various diseases, suggesting they may serve as an alternative strategy of stem cells transplantation. Exosomes have a fundamental role in communication between cells, through the transfer of proteins, bioactive lipids and nucleic acids (like miRNAs and mRNAs) between cells. This transfer significantly impacts both the physiological and pathological functions of recipient cells. Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor, is able to mitigate damage caused by oxidative stress and inflammation through various signaling pathways. The positive effects resulting from the activation of the Nrf2 signaling pathway in different disorders have been documented in various types of literature. Studies have confirmed that exosomes derived from stem cells could act as Nrf2 effective agonists. However, limited studies have explored the Nrf2 role in the therapeutic effects of stem cell-derived exosomes. This review provides a comprehensive overview of the existing knowledge concerning the role of Nrf2 signaling pathways in the impact exerted by stem cell exosomes in some common diseases.

The potential role of stem cells-derived extracellular vesicles in the treatment of musculoskeletal system diseases

The therapeutic potential of stem cells-derived extracellular vesicles (EVs) has shown a great progress in the regenerative medicine. EVs are rich in a variety of bioactive substances, which are important carriers of signal transmission and interactions between cells, and they play an important role in the processes of tissue repair and regeneration. Several studies have shown that stem cells-derived EVs regulate immunity, promote cell proliferation and differentiation, enhance bone and vascular regeneration, and play an increasingly important role in musculoskeletal system. This review aimed to describe the biological characteristics of stem cells-derived EVs and discuss their potential role in the therapy of musculoskeletal system diseases.

Therapeutic potential of mesenchymal stem cell-derived exosomes for regenerative medicine applications

Mesenchymal stem cell-derived exosomes have emerged as a promising cell-free therapy for tissue engineering. Compared to intact stem cells, exosomes have advantages like low immunogenicity and ability to carry regenerative cargo. This review examined the potential of exosomes to treat defects in skin, bone and cartilage. In preclinical models, exosomes improved wound healing, stimulated bone regeneration, and enabled cartilage repair by transferring proteins, mRNAs and microRNAs. Their effects were elicited by modulating inflammation, angiogenesis, cell proliferation and matrix synthesis. Exosomes represent a promising cell-free therapy for tissue engineering. However, challenges remain regarding scalable isolation, elucidating mechanisms, and translating this approach to human trials. Understanding these challenges will enable the successful clinical translation of exosomes for regenerative medicine applications.

CD73-positive pediatric urethral mesenchymal stem-like cell-derived small extracellular vesicles stimulate angiogenesis

Introduction

Angiogenesis plays an important role in the repair of urethral injury, and stem cells and their secretomes can promote angiogenesis. We obtained pediatric urethral mesenchymal stem-like cells (PU-MSLCs) in an earlier study. This project studied the pro-angiogenic effect of PU-MSLC-derived small extracellular vesicles (PUMSLC-sEVs) and the underlying mechanisms.

Materials and methods

PUMSLCs and PUMSLC-sEVs were cultivated and identified. Then, biological methods such as the ethynyl deoxyuridine (EdU) incorporation assay, Cell Counting Kit-8 (CCK-8) assay, scratch wound assay, Transwell assay, and tube formation assay were used to study the effect of PUMSLC-sEVs on the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs). We explored whether the proangiogenic effect of PUMSLC-sEVs is related to CD73 and whether adenosine (ADO, a CD73 metabolite) promoted angiogenesis. GraphPad Prism 8 software was used for data analysis.

Results

We observed that PUMSLC-sEVs significantly promoted the proliferation, migration, and tube-forming abilities of HUVECs. PUMSLC-sEVs delivered CD73 molecules to HUVECs to promote angiogenesis. The angiogenic ability of HUVECs was enhanced after treatment with extracellular ADO produced by CD73, and PUMSLC-sEVs further promoted angiogenesis by activating Adenosine Receptor A2A (A2AR).

Conclusions

These observations suggest that PUMSLC-sEVs promote angiogenesis, possibly through activation of the CD73/ADO/A2AR signaling axis.

A new strategy for intervertebral disc regeneration: The synergistic potential of mesenchymal stem cells and their extracellular vesicles with hydrogel scaffolds

Intervertebral disc degeneration (IDD) is a disease that severely affects spinal health and is prevalent worldwide. Mesenchymal stem cells (MSCs) and their derived extracellular vesicles (EVs) have regenerative potential and have emerged as promising therapeutic tools for treating degenerative discs. However, challenges such as the harsh microenvironment of degenerated intervertebral discs and EVs' limited stability and efficacy have hindered their clinical application. In recent years, hydrogels have attracted much attention in the field of IDD therapy because they can mimic the physiologic microenvironment of the disc and provide a potential solution by providing a suitable growth environment for MSCs and EVs. This review introduced the biological properties of MSCs and their derived EVs, summarized the research on the application of MSCs and EVs in IDD, summarized the current clinical trial studies of MSCs and EVs, and also explored the mechanism of action of MSCs and EVs in intervertebral discs. In addition, plenty of research elaborated on the mechanism of action of different classified hydrogels in tissue engineering, the synergistic effect of MSCs and EVs in promoting intervertebral disc regeneration, and their wide application in treating IDD. Finally, the challenges and problems still faced by hydrogel-loaded MSCs and EVs in the treatment of IDD are summarized, and potential solutions are proposed. This paper outlines the synergistic effects of MSCs and EVs in treating IDD in combination with hydrogels and aims to provide theoretical references for future related studies.

Enhancing osteoporosis treatment with engineered mesenchymal stem cell-derived extracellular vesicles: mechanisms and advances

As societal aging intensifies, the incidence of osteoporosis (OP) continually rises. OP is a skeletal disorder characterized by reduced bone mass, deteriorated bone tissue microstructure, and consequently increased bone fragility and fracture susceptibility, typically evaluated using bone mineral density (BMD) and T-score. Not only does OP diminish patients' quality of life, but it also imposes a substantial economic burden on society. Conventional pharmacological treatments yield limited efficacy and severe adverse reactions. In contemporary academic discourse, mesenchymal stem cells (MSCs) derived extracellular vesicles (EVs) have surfaced as auspicious novel therapeutic modalities for OP. EVs can convey information through the cargo they carry and have been demonstrated to be a crucial medium for intercellular communication, playing a significant role in maintaining the homeostasis of the bone microenvironment. Furthermore, various research findings provide evidence that engineered strategies can enhance the therapeutic effects of EVs in OP treatment. While numerous reviews have explored the progress and potential of EVs in treating degenerative bone diseases, research on using EVs to address OP remains in the early stages of basic experimentation. This paper reviews advancements in utilizing MSCs and their derived EVs for OP treatment. It systematically examines the most extensively researched MSC-derived EVs for treating OP, delving not only into the molecular mechanisms of EV-based OP therapy but also conducting a comparative analysis of the strengths and limitations of EVs sourced from various cell origins. Additionally, the paper emphasizes the technical and engineering strategies necessary for leveraging EVs in OP treatment, offering insights and recommendations for future research endeavors.

Human-Induced Pluripotent Stem Cells in Plastic and Reconstructive Surgery

A hallmark of plastic and reconstructive surgery is restoring form and function. Historically, tissue procured from healthy portions of a patient's body has been used to fill defects, but this is limited by tissue availability. Human-induced pluripotent stem cells (hiPSCs) are stem cells derived from the de-differentiation of mature somatic cells. hiPSCs are of particular interest in plastic surgery as they have the capacity to be re-differentiated into more mature cells, and cultured to grow tissues. This review aims to evaluate the applications of hiPSCs in the plastic surgery context, with a focus on recent advances and limitations. The use of hiPSCs and non-human iPSCs has been researched in the context of skin, nerve, vasculature, skeletal muscle, cartilage, and bone regeneration. hiPSCs offer a future for regenerated autologous skin grafts, flaps comprised of various tissue types, and whole functional units such as the face and limbs. Also, they can be used to model diseases affecting tissues of interest in plastic surgery, such as skin cancers, epidermolysis bullosa, and scleroderma. Tumorigenicity, immunogenicity and pragmatism still pose significant limitations. Further research is required to identify appropriate somatic origin and induction techniques to harness the epigenetic memory of hiPSCs or identify methods to manipulate epigenetic memory.

Understanding exosomes: Part 2-Emerging leaders in regenerative medicine

Exosomes are the smallest subset of extracellular signaling vesicles secreted by most cells with the ability to communicate with other tissues and cell types over long distances. Their use in regenerative medicine has gained tremendous momentum recently due to their ability to be utilized as therapeutic options for a wide array of diseases/conditions. Over 5000 publications are currently being published yearly on this topic, and this number is only expected to dramatically increase as novel therapeutic strategies continue to be developed. Today exosomes have been applied in numerous contexts including neurodegenerative disorders (Alzheimer's disease, central nervous system, depression, multiple sclerosis, Parkinson's disease, post-traumatic stress disorders, traumatic brain injury, peripheral nerve injury), damaged organs (heart, kidney, liver, stroke, myocardial infarctions, myocardial infarctions, ovaries), degenerative processes (atherosclerosis, diabetes, hematology disorders, musculoskeletal degeneration, osteoradionecrosis, respiratory disease), infectious diseases (COVID-19, hepatitis), regenerative procedures (antiaging, bone regeneration, cartilage/joint regeneration, osteoarthritis, cutaneous wounds, dental regeneration, dermatology/skin regeneration, erectile dysfunction, hair regrowth, intervertebral disc repair, spinal cord injury, vascular regeneration), and cancer therapy (breast, colorectal, gastric cancer and osteosarcomas), immune function (allergy, autoimmune disorders, immune regulation, inflammatory diseases, lupus, rheumatoid arthritis). This scoping review is a first of its kind aimed at summarizing the extensive regenerative potential of exosomes over a broad range of diseases and disorders.

Non-bone-derived exosomes: a new perspective on regulators of bone homeostasis

Accumulating evidence indicates that exosomes help to regulate bone homeostasis. The roles of bone-derived exosomes have been well-described; however, recent studies have shown that some non-bone-derived exosomes have better bone targeting ability than bone-derived exosomes and that their performance as a drug delivery vehicle for regulating bone homeostasis may be better than that of bone-derived exosomes, and the sources of non-bone-derived exosomes are more extensive and can thus be better for clinical needs. Here, we sort non-bone-derived exosomes and describe their composition and biogenesis. Their roles and specific mechanisms in bone homeostasis and bone-related diseases are also discussed. Furthermore, we reveal obstacles to current research and future challenges in the practical application of exosomes, and we provide potential strategies for more effective application of exosomes for the regulation of bone homeostasis and the treatment of bone-related diseases. Video Abstract.