Purified exosome product enhances chondrocyte survival and regeneration by modulating inflammation and promoting chondrogenesis

Evaluating purified exosome product and its role in neurologic and functional recovery following spinal cord injury in female rats

INTRODUCTION

Exosomes represent extracellular vesicles that mediate intercellular interactions and have been extensively studied for their therapeutic potential. Purified exosomes product (PEP) from human plasma is reported to aid in tissue repair but has never been evaluated as a potential therapy for spinal cord injury (SCI).

OBJECTIVE

We aim to investigate the effects of PEP on axon myelination, reduction in cavity size, and functional improvements in rats following SCI.

METHODS

Following T9-T10 laminectomy and contusion to the spinal cord, female rats received either intrathecal (IT) PEP, IT ringer-lactate solution (RL), intravenous (IV) PEP, or IV RL one day post injury. Rats underwent behavioral assessments each week for 10 weeks following SCI. After 10 weeks, histological evaluations were performed to quantity axon myelination and cavity size.

RESULTS

The IT PEP group had significantly (P ≤ 0.05) more myelinated axons 1000 μm rostral to the injury, at the epicenter, and 1000 μm caudal of the injury (34.3 ± 3.1, 27.7 ± 2.1, and 32.0 ± 1.7, respectively) compared to the IT RL group (27.3 ± 2.5, 17.3 ± 2.5, and 23.3 ± 2.5, respectively). In addition, IT PEP rats had significantly reduced cavity size at the injury epicenter compared to controls (28.31%±1.74% vs. 34.39%±3.78%, respectively). Lastly, functional improvements were observed and sustained beginning at the 31 days following injury. The IV PEP group did not show sustained functional improvement compared to the IV RL rats.

CONCLUSION

Our results suggest that IT PEP injection may yield beneficial effects following SCI. However, further studies are warranted to investigate the role of PEP following SCI and to optimize its potential for clinical translation.

Therapeutic effects of platelet-derived extracellular vesicles on viral myocarditis correlate with biomolecular content

Introduction

Extracellular vesicles (EVs) can potently inhibit inflammation yet there is a lack of understanding about the impact of donor characteristics on the efficacy of EVs. The goal of this study was to determine whether the sex and age of donor platelet-derived EVs (PEV) affected their ability to inhibit viral myocarditis.

Methods

PEV, isolated from men and women of all ages, was compared to PEV obtained from women under 50 years of age, which we termed premenopausal PEV (pmPEV). Because of the protective effect of estrogen against myocardial inflammation, we hypothesized that pmPEV would be more effective than PEV at inhibiting myocarditis. We injected PEV, pmPEV, or vehicle control in a mouse model of viral myocarditis and examined histology, gene expression, protein profiles, and performed proteome and microRNA (miR) sequencing of EVs.

Results

We found that both PEV and pmPEV significantly inhibited myocarditis; however, PEV was more effective, which was confirmed by a greater reduction of inflammatory cells and proinflammatory and profibrotic markers determined using gene expression and immunohistochemistry. Proteome and miR sequencing of EVs revealed that PEV miRs specifically targeted antiviral, Toll-like receptor (TLR)4, and inflammasome pathways known to contribute to myocarditis while pmPEV contained general immunoregulatory miRs.

Discussion

These differences in EV content corresponded to the differing anti-inflammatory effects of the two types of EVs on viral myocarditis.

Extracellular vesicles from platelet-poor plasma possess anti-inflammatory and anti-catabolic effects in chondrocytes stimulated with IL-1β or synovial membrane-conditioned media

BACKGROUND

Although osteoarthritis (OA) is the most prevalent form of arthritis, there is still no effective treatment capable of combining immunomodulatory effects with cartilage repair. Extracellular vesicles (EVs) represent a promising new generation of cell-free therapies for OA. Blood-derived products, including plasma, are an easily available and abundant source of EVs with anti-inflammatory and regenerative properties. In this study, our objective was to analyze the effect of platelet poor plasma-derived extracellular vesicles (PPP-EVs) on stimulated OA chondrocytes in vitro. We hypothesize that PPP from healthy donors could be a suitable source of EVs that can modulate the inflammatory environment of OA chondrocytes.

METHODS

Cartilage and synovial membrane (SM) were obtained from patients with OA and whole blood from healthy donors. Synovial membrane-conditioned media (CM / SM) was analyzed using multiplex immunoassays. EVs were isolated from PPP using size exclusion chromatography (SEC) and characterized by nanoparticle tracking analysis (NTA), Western blot, and flow cytometry (FC). The phenotype of the chondrocytes was analyzed using fluorescence microscopy and RT-qPCR. Chondrocytes were stimulated with IL-1β or CM/SM for 24 h. The impact of PPP-EVs on stimulated chondrocyte gene expression was evaluated using RT-qPCR.

RESULTS

The PPP-EVs isolated by SEC were positive for the tetraspanins CD9, CD63, and CD81. The chondrocyte phenotype was confirmed by positive expression of Collagen II and Aggrecane. CM/SM and IL-1β caused inflammatory changes in chondrocytes, which was observed by increased expression of the genes MMP-1, MMP-3 and MMP-13, RANTES, TSG-6, and YKL-40 compared to the control. PPP-EVs added to stimulated chondrocytes for 24 h significantly decreased the expression of the chondrocyte gene YKL-40, TSG-6 and MMP-1.

CONCLUSIONS

In this study, we confirmed that PPP is a suitable source of EVs, which can be efficiently isolated by SEC. We found that PPP-EVs were capable of decreasing the expression of inflammatory genes in OA chondrocytes stimulated with IL-1β or CM/SM. This study provides preliminary results on PPP-EVs as an affordable and promising option to modulate the catabolic microenvironment of OA chondrocytes in vitro.

Advances in regulating endothelial-mesenchymal transformation through exosomes

Endothelial-mesenchymal transformation (EndoMT) is the process through which endothelial cells transform into mesenchymal cells, affecting their morphology, gene expression, and function. EndoMT is a potential risk factor for cardiovascular and cerebrovascular diseases, tumor metastasis, and fibrosis. Recent research has highlighted the role of exosomes, a mode of cellular communication, in the regulation of EndoMT. Exosomes from diseased tissues and microenvironments can promote EndoMT, increase endothelial permeability, and compromise the vascular barrier. Conversely, exosomes derived from stem cells or progenitor cells can inhibit the EndoMT process and preserve endothelial function. By modifying exosome membranes or contents, we can harness the advantages of exosomes as carriers, enhancing their targeting and ability to inhibit EndoMT. This review aims to systematically summarize the regulation of EndoMT by exosomes in different disease contexts and provide effective strategies for exosome-based EndoMT intervention.

Nebulized platelet-derived extracellular vesicles attenuate chronic cigarette smoke-induced murine emphysema

Chronic obstructive pulmonary disease (COPD) is a prevalent lung disease usually resulting from cigarette smoking (CS). Cigarette smoking induces oxidative stress, which causes inflammation and alveolar epithelial cell apoptosis and represents a compelling therapeutic target for COPD. Purified human platelet-derived exosome product (PEP) is endowed with antioxidant enzymes and immunomodulatory molecules that mediate tissue repair. In this study, a murine model of CS-induced emphysema was used to determine whether nebulized PEP can influence the development of CS-induced emphysema through the mitigation of oxidative stress and inflammation in the lung. Nebulization of PEP effectively delivered the PEP vesicles into the alveolar region, with evidence of their uptake by type I and type II alveolar epithelial cells and macrophages. Lung function testing and morphometric assessment showed a significant attenuation of CS-induced emphysema in mice treated with nebulized PEP thrice weekly for 4 weeks. Whole lung immuno-oncology RNA sequencing analysis revealed that PEP suppressed several CS-induced cell injuries and inflammatory pathways. Validation of inflammatory cytokines and apoptotic protein expression on the lung tissue revealed that mice treated with PEP had significantly lower levels of S100A8/A9 expressing macrophages, higher levels of CD4+/FOXP3+ Treg cells, and reduced NF-κB activation, inflammatory cytokine production, and apoptotic proteins expression. Further validation using in vitro cell culture showed that pretreatment of alveolar epithelial cells with PEP significantly attenuated CS extract-induced apoptotic cell death. These data show that nebulization of exosomes like PEP can effectively deliver exosome cargo into the lung, mitigate CS-induced emphysema in mice, and suppress oxidative lung injury, inflammation, and apoptotic alveolar epithelial cell death.

The crosstalk between exosomes and ferroptosis: a review

Exosomes are a subtype of extracellular vesicles composed of bioactive molecules, including nucleic acids, proteins, and lipids. Exosomes are generated by the fusion of intracellular multivesicular bodies (MVBs) with the cell membrane and subsequently released into the extracellular space to participate in intercellular communication and diverse biological processes within target cells. As a crucial mediator, exosomes have been implicated in regulating ferroptosis-an iron-dependent programmed cell death characterized by lipid peroxide accumulation induced by reactive oxygen species. The involvement of exosomes in iron, lipid, and amino acid metabolism contributes to their regulatory role in specific mechanisms underlying how exosomes modulate ferroptosis, which remains incompletely understood, and some related studies are still preliminary. Therefore, targeting the regulation of ferroptosis by exosomes holds promise for future clinical treatment strategies across various diseases. This review aims to provide insights into the pathophysiology and mechanisms governing the interaction between exosomes and ferroptosis and their implications in disease development and treatment to serve as a reference for further research.

The Effect of Local Purified Exosome Product, Stem Cells, and Tacrolimus on Neurite Extension

PURPOSE

The combination of cellular and noncellular treatments has been postulated to improve nerve regeneration through a processed nerve allograft. This study aimed to evaluate the isolated effect of treatment with purified exosome product (PEP), mesenchymal stem cells (MSCs), and tacrolimus (FK506) alone and in combination when applied in decellularized allografts.

METHODS

A three-dimensional in vitro-compartmented cell culture system was used to evaluate the length of regenerating neurites from the neonatal dorsal root ganglion into the adjacent peripheral nerve graft. Decellularized nerve allografts were treated with undifferentiated MSCs, 5% PEP, 100 ng/mL FK506, PEP and FK506 combined, or MSCs and FK506 combined (N = 9/group) and compared with untreated nerve autografts (positive control) and nerve allografts (negative control). Neurite extension was measured to quantify nerve regeneration after 48 hours, and stem cell viability was evaluated.

RESULTS

Stem cell viability was confirmed in all MSC-treated nerve grafts. Treatments with PEP, PEP + FK506, and MSCs + FK506 combined were found to be superior to untreated allografts and not significantly different from autografts. Combined PEP and FK506 treatment resulted in the greatest neurite extension. Treatment with FK506 and MSCs was significantly superior to MSC alone. The combined treatment groups were not found to be statistically different.

CONCLUSIONS

Although all treatments improved neurite outgrowth, treatments with PEP, PEP + FK506, and MSCs + FK506 combined had superior neurite growth compared with untreated allografts and were not found to be significantly different from autografts, the current gold standard.

CLINICAL RELEVANCE

Purified exosome product, a cell-free exosome product, is a promising adjunct to enhance nerve allograft regeneration, with possible future avenues for clinical translation.

The Role of Exosomes in Upper-Extremity Tissue Regeneration

Exosomes are cell-free membrane vesicles secreted by a wide variety of cells as secretomes into the extracellular matrix. Alongside facilitating intercellular communication, exosomes carry various bioactive molecules consisting of nucleic acids, proteins, and lipids. Exosome applications have increased in popularity by overcoming the disadvantages of mesenchymal stem cell therapies. Despite this, a better understanding of the underlying mechanisms of action of exosomes is necessary prior to clinical application in upper-extremity tissue regeneration. The purpose of this review is to introduce the concept of exosomes and their possible applications in upper-extremity tissue regeneration, detail the shortcomings of current exosome research, and explore their potential clinical application in the upper extremity.

Reconstituted Extracellular Vesicles from Human Platelets Decrease Viral Myocarditis in Mice

Patients with viral myocarditis are at risk of sudden death and may progress to dilated cardiomyopathy (DCM). Currently, no disease-specific therapies exist to treat viral myocarditis. Here it is examined whether reconstituted, lyophilized extracellular vesicles (EVs) from platelets from healthy men and women reduce acute or chronic myocarditis in male mice. Human-platelet-derived EVs (PEV) do not cause toxicity, damage, or inflammation in naïve mice. PEV administered during the innate immune response significantly reduces myocarditis with fewer epidermal growth factor (EGF)-like module-containing mucin-like hormone receptor-like 1 (F4/80) macrophages, T cells (cluster of differentiation molecules 4 and 8, CD4 and CD8), and mast cells, and improved cardiac function. Innate immune mediators known to increase myocarditis are decreased by innate PEV treatment including Toll-like receptor (TLR)4 and complement. PEV also significantly reduces perivascular fibrosis and remodeling including interleukin 1 beta (IL-1β), transforming growth factor-beta 1, matrix metalloproteinase, collagen genes, and mast cell degranulation. PEV given at days 7-9 after infection reduces myocarditis and improves cardiac function. MicroRNA (miR) sequencing reveals that PEV contains miRs that decrease viral replication, TLR4 signaling, and T-cell activation. These data show that EVs from the platelets of healthy individuals can significantly reduce myocarditis and improve cardiac function.

Enhancement of Chondrogenic Markers by Exosomes Derived from Cultured Human Synovial Fluid-Derived Cells: A Comparative Analysis of 2D and 3D Conditions

OBJECTIVE

The goal of this pilot study was to investigate the effects of exosomes derived from synovial fluid-derived cells (SFDCs) cultured under normoxic conditions in a two-dimensional (2D) monolayer or encapsulated within a three-dimensional (3D) matrix for chondrogenic differentiation in vitro and cartilage defect repair in vivo.

DESIGN

Synovial fluid samples were obtained from three patients, and SFDCs were isolated and expanded either in a 2D monolayer culture or seeded within a transglutaminase cross-linked gelatin (Col-Tgel) to create a 3D gel culture. Exosomes derived from each environment were isolated and characterized. Then, their effects on cartilage-cell proliferation and chondrogenic differentiation were assessed using an in vitro organoid model, and their potential for enhancing cartilage repair was evaluated using a rat cartilage defect model.

RESULTS

SFDCs obtained from different donors reached a state of senescence after four passages in 2D culture. However, transferring these cells to a 3D culture environment mitigated the senescence and improved cell viability. The 3D-cultured exosomes exhibited enhanced potency in promoting chondrogenic differentiation, as evidenced by the increased expression of chondrogenic genes and greater deposition of cartilage-specific extracellular matrix. Furthermore, the 3D-cultured exosomes demonstrated superior effectiveness in enhancing cartilage repair and exhibited better healing properties compared to exosomes derived from a 2D culture.

CONCLUSIONS

The optimized 3D culture provided a more favorable environment for the proliferation of human synovial cells and the secretion of exosomes compared to the 2D culture. The 3D-cultured exosomes exhibited greater potential for promoting chondrogenic gene expression in vitro and demonstrated improved healing properties in repairing cartilage defects compared to exosomes derived from the 2D culture.

Dose-response analysis after administration of a human platelet-derived exosome product on neurite outgrowth in vitro

Modulating the nerve's local microenvironment using exosomes is proposed to enhance nerve regeneration. This study aimed to determine the optimal dose of purified exosome product (PEP) required to exert maximal neurite extension. An in vitro dorsal root ganglion (DRG) neurite outgrowth assay was used to evaluate the effect of treatment with (i) 5% PEP, (ii) 10% PEP, (iii) 15% PEP, or (iv) 20% PEP on neurite extension (N = 9/group), compared to untreated controls. After 72 h, neurite extension was measured to quantify nerve regeneration. Live cell imaging was used to visualize neurite outgrowth during incubation. Treatment with 5% PEP resulted in the longest neurite extension and was superior to the untreated DRG (p = 0.003). Treatment with 10% PEP, 15% PEP, and 20% PEP was found to be comparable to controls (p = 0.12, p = 0.06, and p = 0.41, respectively) and each other. Live cell imaging suggested that PEP migrated towards the DRG neural regeneration site, compared to the persistent homogenous distribution of PEP in culture media alone. 5% PEP was found to be the optimal concentration for nerve regeneration based on this in vitro dose-response analysis.