Recent advances of exosomes in soft tissue injuries in sports medicine: A critical review on biological and biomaterial applications

Biomass bilayer membranes with an asymmetric structure to promote a tendon-bone interface healing mechanism

Biologically, tendon-bone interface healing needs to overcome two problems: tendon dislocation and scar tissue proliferation at the interface. Because of the above problems, we proposed a bone tunnel membrane to aid tendon-bone interface healing. This study aims to explore the effects of absorbable membranes with different surface morphologies on tendon-bone interface healing. At the tendon-bone interface, the tendon graft was wrapped with a bilayer flexible absorbable membrane and implanted into the bone tunnel. Using the micron topological structure on the surface of the membrane to accelerate tendon healing and osteogenic differentiation provides environmental support for the healing of the two tissue interfaces. The different topological structures on the surface of the material can promote the oriented differentiation of cells. The micron groove structure can arrange fibroblasts according to orientation, promote tendon bundle healing, change cell morphology, and secrete tendon specific proteins to promote tendon repair. The porous structure can promote cell osteogenic differentiation and accelerate bone integration. After in vivo experimental analysis, the material is suitable for the adjuvant treatment of tendon-bone healing. Therefore, this study provides a new treatment idea for accelerating tendon-to-bone healing.

Enhanced Compressive Strength of PVA/SA Composite Hydrogel by Highly Dispersed Hydroxyapatite Nanofibers

Rapid functional soft tissue restoration has shown considerable promise as a framework for stability and coordination in the human body. Inspired by the anisotropic arrangement of structures with soft and hard phases in biological tissues, such as tendon, cartilage, and ligament, many methods have been used to fabricate composite hydrogels with appropriate mechanical properties. The development of a high-strength hydrogel with strong bioactivity remains a key barrier to replace soft tissues with comparable synthetic structures. In this study, a highly dispersed hydroxyapatite nanofiber (HANF) reinforced polyvinyl alcohol-sodium alginate (PVA/SA) composite hydrogel is prepared for soft tissue replacement. The effect of the addition of HANF on the microstructure and properties of composite hydrogel is also investigated. The results show that the PVA/SA hydrogel, after the incorporation of HANF, combines well with the PVA/SA hydrogel (HANF@PVA/SA). SEM morphologies show that dispersed HANF can enter the holes of the three-dimensional structure of the composite hydrogel. Additionally, the addition of HANF can enhance the compressive strength of the PVA/SA composite hydrogel from 4.66 MPa to 7.72 MPa. At the same time, the HANF@PVA/SA hydrogel maintains the same excellent hydrophilicity as the original PVA/SA hydrogel. Finally, cytotoxicity and live/dead cell staining tests also confirmed its excellent biocompatibility, demonstrating its tremendous potential for use in soft tissue repair.

Dermal Fibroblast-Derived Exosomes Promotes Bone-to-Tendon Interface Healing of Chronic Rotator Cuff Tear in Rabbit Model

PURPOSE

To investigate the efficacy of exosomes derived from dermal fibroblasts (DF-Ex) on bone-to-tendon interface (BTI) healing in a chronic rotator cuff tear (RCT) model of rabbit.

METHODS

After extraction of DF-Ex, the characterization of DF-Ex was identified in the in vitro study. In the in vivo experiment, 48 rabbits were randomly allocated into 3 groups. To create chronic RCT models, transected tendons were left untreated for 6 weeks and then were repaired in a transosseous manner. Different materials were injected into repair site according to the allocated group (group A: saline, group B: fibrin glue only, group C: DF-Ex with fibrin glue; n = 16 for each). Genetic and immunofluorescence analyses were conducted at 4 weeks post-surgery. Furthermore, genetic, histologic, and biomechanical analyses were conducted at 12 weeks post-surgery.

RESULTS

In vitro analyses revealed the exosomal marker proteins CD9, CD63, and ALIX were positively expressed in DF-Ex, whereas negative control Calnexin was nearly absent. In vivo analyses showed that group C had the highest mRNA expression levels of COL1A1, COL3A1, and ACAN among all groups (P < .001, P = .007, and P = .002, respectively) at 4 weeks postsurgery. Meanwhile, there were more preliminary fibrocartilaginous matrix (aggrecan+/collagen II+) formation in group C. At 12 weeks postsurgery, group C had better collagen fiber continuity and orientation, denser collagen fibers, more mature bone-to-tendon junction, and greater fibrocartilage layer formation compared with the other groups (all P < .05). Moreover, group C also had greater load-to-failure value (53.3 ± 6.1 N/kg, P < .001).

CONCLUSIONS

Topical DF-Ex administration effectively promoted BTI healing by upregulating the COL1A1, COL3A1, and ACAN mRNA expression levels at an early stage and enhancing the structural and biomechanical properties at 12 weeks after surgical repair of a chronic RCT model of rabbit.

CLINICAL RELEVANCE

The study could be a transitional study to investigate the efficacy of DF-Ex on BTI healing for surgical repair of chronic RCTs as a powerful biological agent in humans.

Macrophage membrane-encapsulated miRNA nanodelivery system for the treatment of hemophilic arthritis

Hemophilic arthritis (HA) is one of the most pathologically altered joint diseases. Specifically, periodic spontaneous hemorrhage-induced hyperinflammation of the synovium and irreversible destruction of the cartilage are the main mechanisms that profoundly affect the behavioral functioning and quality of life of patients. In this study, we isolated and characterized platelet-rich plasma-derived exosomes (PRP-exo). We performed microRNA (miRNA) sequencing and bioinformatics analysis on these exosomes to identify the most abundant miRNA, miR-451a. Following this, we developed an M@ZIF-8@miR nanotherapeutic system that utilizes nanoscale zeolitic imidazolate framework (ZIF) as a carrier for miRNA delivery, encapsulated within M2 membranes to enhance its anti-inflammatory effects. In vitro and in vivo studies demonstrated that M@ZIF-8@miR significantly reduced pro-inflammatory cytokines, controlled synovial inflammation, and achieved potent therapeutic efficacy by reducing joint damage. We suggest that the ability of M@ZIF-8@miR nanocomposites to inhibit pro-inflammatory cytokines, enhance cellular uptake, and exhibit good endosomal escape properties makes them promising carriers for the efficient delivery of therapeutic nucleic acid drugs. This approach delays joint degeneration and provides a promising combinatorial strategy for HA treatment.

Injectable decellularized Wharton's jelly hydrogel containing CD56+ umbilical cord mesenchymal stem cell-derived exosomes for meniscus tear healing and cartilage protection

Traditional meniscectomy or suture for meniscal tear usually leads to failed self-healing, cartilage degeneration and worse osteoarthritis. The strategies that facilitate the healing process of torn meniscus and safeguard knee cartilage against degeneration will be promising for clinical therapy. The CD56+ umbilical cord mesenchymal stem cells (UCSCs) (CD56+UCSCs) were sorted from Wharton's jelly using flow cytometer. Then, the modified decellularized Wharton's Jelly hydrogel (DWJH) was combined with isolated CD56+Exos from CD56+UCSCs to fabricate DWJH/CD56+Exos. The in vitro studies were performed to characterize the DWJ (decellularized Wharton's Jelly). The injectability and rheological properties were assessed by shear rate and frequency sweep analysis. The biocompatibility and chondrogenic differentiation inducibility of DWJH/CD56+Exos were performed on human bone marrow mesenchymal stem cells (hBMSCs) and RAW 264.7 cells. The release dynamics was evaluated in vitro and in vivo experiments. As for the in vivo experiments, the operated rats that subjected to a 2 mm full-thickness longitudinal tear in right medial anterior meniscus were injected a single dose of DWJH/CD56+Exos. At 4 and 8 weeks postoperatively, torn meniscus healing and articular cartilage degeneration were evaluated by hematoxylin and eosin (H&E), safranin O/fast green (SO&FG), and Sirius red staining. In in vitro experiments, the injectable DWJH/CD56+Exos demonstrated excellent biocompatibility, exosome releasing efficiency, injectable property and chondrogenic inducibility. The results of in vivo experiments revealed that DWJH/CD56+Exos degraded over time, promoted meniscal chondrogenesis, organized meniscal extracellular matrix remodeling, safeguard articular cartilage and inhibited secondary cartilage degeneration, which accelerated further facilitated torn meniscus healing. The novel injectable DWJH/CD56+Exos promoted meniscal tear healing by promoting meniscal chondrogenesis, safeguarding articular cartilage, and inhibiting secondary cartilage degeneration.

ROS-responsive MSC-derived Exosome Mimetics Carrying MHY1485 Alleviate Renal Ischemia Reperfusion Injury through Multiple Mechanisms

Renal ischemia reperfusion (IR) injury is a prevalent inflammatory nephropathy in surgeries such as renal transplantation or partial nephrectomy, damaging renal function through inducing inflammation and cell death in renal tubules. Mesenchymal stromal/stem cell (MSC)-based therapies, common treatments to attenuate inflammation in IR diseases, fail to exhibit satisfying effects on cell death in renal IR. In this study, we prepared MSC-derived exosome mimetics (EMs) carrying the mammalian target of the rapamycin (mTOR) agonist to protect kidneys in proinflammatory environments under IR conditions. The thioketal-modified EMs carried the mTOR agonist and bioactive molecules in MSCs and responsively released them in kidney IR areas. MSC-derived EMs and mTOR agonists protected kidneys synergistically from IR through alleviating inflammation, apoptosis, and ferroptosis. The current study indicates that MSC-TK-MHY1485 EMs (MTM-EM) are promising therapeutic biomaterials for renal IR injury.

Mesenchymal stem cell-derived extracellular vesicles: a regulator and carrier for targeting bone-related diseases

The escalating threat of bone-related diseases poses a significant challenge to human health. Mesenchymal stem cell (MSC)-derived extracellular vesicles (MSC-EVs), as inherent cell-secreted natural products, have emerged as promising treatments for bone-related diseases. Leveraging outstanding features such as high biocompatibility, low immunogenicity, superior biological barrier penetration, and extended circulating half-life, MSC-EVs serve as potent carriers for microRNAs (miRNAs), long no-code RNAs (lncRNAs), and other biomolecules. These cargo molecules play pivotal roles in orchestrating bone metabolism and vascularity through diverse mechanisms, thereby contributing to the amelioration of bone diseases. Additionally, engineering modifications enhance the bone-targeting ability of MSC-EVs, mitigating systemic side effects and bolstering their clinical translational potential. This review comprehensively explores the mechanisms through which MSC-EVs regulate bone-related disease progression. It delves into the therapeutic potential of MSC-EVs as adept drug carriers, augmented by engineered modification strategies tailored for osteoarthritis (OA), rheumatoid arthritis (RA), osteoporosis, and osteosarcoma. In conclusion, the exceptional promise exhibited by MSC-EVs positions them as an excellent solution with considerable translational applications in clinical orthopedics.

Extracellular Vesicles and Exosomes in the Control of the Musculoskeletal Health

PURPOSE OF REVIEW

The present review will highlight recent reports supporting the relevance of extracellular vesicles to the musculoskeletal system in health and disease.

RECENT FINDINGS

Preserving the health of the musculoskeletal system is important to maintain a good quality of life, and the bone-muscle crosstalk is crucial in this regard. This latter is largely mediated by extracellular vesicles released by the different cell populations residing in muscle and bone, which deliver cargoes, microRNAs, and proteins being the most relevant ones, to target cells. Extracellular vesicles could be exploited as therapeutic tools, in view of their resistance to destruction in the biological fluid and of the possibility to be functionalized according to the need. Extracellular vesicles are recognized as crucial players in the bone-muscle cross-talk. Additional studies however are required to refine their use as biomarkers of early alterations of the musculoskeletal system, and as potential therapeutic tools.

Engineered exosomes in emerging cell-free therapy

The discovery and use of exosomes ushered in a new era of cell-free therapy. Exosomes are a subgroup of extracellular vesicles that show great potential in disease treatment. Engineered exosomes. with their improved functions have attracted intense interests of their application in translational medicine research. However, the technology of engineering exosomes still faces many challenges which have been the great limitation for their clinical application. This review summarizes the current status of research on engineered exosomes and the difficulties encountered in recent years, with a view to providing new approaches and ideas for future exosome modification and new drug development.

Optimizing tendon repair and regeneration: how does the in vivo environment shape outcomes following rupture of a tendon such as the Achilles tendon?

Risk for rupture of the Achilles tendon, and other tendons increases with age. Such injuries of tissues that function in high load environments generally are believed to heal with variable outcome. However, in many cases, the healing does not lead to a good outcome and the patient cannot return to the previous level of participation in active living activities, including sports. In the past few years, using proteomic approaches and other biological techniques, reports have appeared that identify biomarkers that are prognostic of good outcomes from healing, and others that are destined for poor outcomes using validated criteria at 1-year post injury. This review will discuss some of these recent findings and their potential implications for improving outcomes following connective tissue injuries, as well as implications for how clinical research and clinical trials may be conducted in the future where the goal is to assess the impact of specific interventions on the healing process, as well as focusing the emphasis on regeneration and not just repair.