Adipose-Derived Mesenchymal Stromal Cells Treated with Interleukin 1 Beta Produced Chondro-Protective Vesicles Able to Fast Penetrate in Cartilage

Engineering exosomes derived from TNF-α preconditioned IPFP-MSCs enhance both yield and therapeutic efficacy for osteoarthritis

BACKGROUND

The pathogenesis of osteoarthritis (OA) involves the progressive degradation of articular cartilage. Exosomes derived from mesenchymal stem cells (MSC-EXOs) have been shown to mitigate joint pathological injury by attenuating cartilage destruction. Optimization the yield and therapeutic efficacy of exosomes derived from MSCs is crucial for promoting their clinical translation. The preconditioning of MSCs enhances the therapeutic potential of engineered exosomes, offering promising prospects for application by enabling controlled and quantifiable external stimulation. This study aims to address these issues by employing pro-inflammatory preconditioning of MSCs to enhance exosome production and augment their therapeutic efficacy for OA.

METHODS

The exosomes were isolated from the supernatant of infrapatellar fat pad (IPFP)-MSCs preconditioned with a pro-inflammatory factor, TNF-α, and their production was subsequently quantified. The exosome secretion-related pathways in IPFP-MSCs were evaluated through high-throughput transcriptome sequencing analysis, q-PCR and western blot analysis before and after TNF-α preconditioning. Furthermore, exosomes derived from TNF-α preconditioned IPFP-MSCs (IPFP-MSC-EXOsTNF-α) were administered intra-articularly in an OA mouse model, and subsequent evaluations were conducted to assess joint pathology and gait alterations. The expression of proteins involved in the maintenance of cartilage homeostasis within the exosomes was determined through proteomic analysis.

RESULTS

The preconditioning with TNF-α significantly enhanced the exosome secretion of IPFP-MSCs compared to unpreconditioned MSCs. The potential mechanism involved the activation of the PI3K/AKT signaling pathway in IPFP-MSCs by TNF-α precondition, leading to an up-regulation of autophagy-related protein 16 like 1(ATG16L1) levels, which subsequently facilitated exosome secretion. The intra-articular administration of IPFP-MSC-EXOsTNF-α demonstrated superior efficacy in ameliorating pathological changes in the joints of OA mice. The preconditioning of TNF-α enhanced the up-regulation of low-density lipoprotein receptor-related protein 1 (LRP1) levels in IPFP-MSC-EXOsTNF-α, thereby exerting chondroprotective effects.

CONCLUSION

TNF-α preconditioning constitutes an effective and promising method for optimizing the therapeutic effects of IPFP-MSCs derived exosomes in the treatment of OA.

A call for standardization for secretome and extracellular vesicles in osteoarthritis: results show disease-modifying potential, but protocols are too heterogeneous-a systematic review

The currently available osteoarthritis (OA) treatments offer symptoms' relief without disease-modifying effects. Increasing evidence supports the role of human mesenchymal stem cells (MSCs) to drive beneficial effects provided by their secretome and extracellular vesicles (EVs), which includes trophic and biologically active factors. Aim of this study was to evaluate the in vitro literature to understand the potential of human secretome and EVs for OA treatment and identify trends, gaps, and potential translational challenges. A systematic review was performed on PubMed, Embase, and Web-of-Science, identifying 58 studies. The effects of secretome and EVs were analysed on osteoarthritic cells regarding anabolic, anti-apoptotic/anti-inflammatory and catabolic/pro-inflammatory/degenerative activity, chondroinduction, and immunomodulation. The results showed that MSC-derived EVs elicit an increase in proliferation and migration, reduction of cell death and inflammation, downregulation of catabolic pathways, regulation of immunomodulation, and promotion of anabolic processes in arthritic cells. However, a high heterogeneity in several technical or more applicative aspects emerged. In conclusion, the use of human secretome and EVs as strategy to address OA processes has overall positive effects and disease-modifying potential. However, it is crucial to reduce protocol variability and strive toward a higher standardization, which will be essential for the translation of this promising OA treatment from the in vitro research setting to the clinical practice.

Donor Sites and Harvesting Techniques Affect miRNA Cargos of Extracellular Vesicles Released by Human Adipose-Derived Mesenchymal Stromal Cells

Osteoarthritis (OA) is a degenerative joint disorder characterized by the progressive deterioration of articular cartilage driven and sustained by catabolic and inflammatory processes that lead to pain and functional impairment. Adipose-derived stem cells (ASCs) have emerged as a promising therapeutic strategy for OA due to their regenerative potential, which mainly relies on the adaptive release of paracrine molecules that are soluble or encapsulated in extracellular vesicles (EVs). The biological effects of EVs specifically depend on their cargo; in particular, microRNAs (miRNAs) can specifically modulate target cell function through gene expression regulation. This study aimed to investigate the impact of collection site (abdominal vs. peri-trochanteric adipose tissue) and collection method (surgical excision vs. lipoaspiration) on the miRNAs profile in ASC-derived EVs and their potential implications for OA therapy. EV-miRNA cargo profiles from ASCs of different origins were compared. An extensive bioinformatics search through experimentally validated and OA-related targets, pathways, and tissues was conducted. Several miRNAs involved in the restoration of cartilage homeostasis and in immunomodulation were identified in all ASC types. However, EV-miRNA expression profiles were affected by both the tissue-harvesting site and procedure, leading to peculiar characteristics for each type. Our results suggest that adipose-tissue-harvesting techniques and the anatomical site of origin influence the therapeutic efficacy of ASC-EVs for tissue-specific regenerative therapies in OA, which warrants further investigation.

Therapeutic potential in rheumatic diseases of extracellular vesicles derived from mesenchymal stromal cells

The incidence of rheumatic diseases such as rheumatoid arthritis and osteoarthritis and injuries to articular cartilage that lead to osteochondral defects is predicted to rise as a result of population ageing and the increase in high-intensity physical activities among young and middle-aged people. Current treatments focus on the management of pain and joint functionality to improve the patient's quality of life, but curative strategies are greatly desired. In the past two decades, the therapeutic value of mesenchymal stromal cells (MSCs) has been evaluated because of their regenerative potential, which is mainly attributed to the secretion of paracrine factors. Many of these factors are enclosed in extracellular vesicles (EVs) that reproduce the main functions of parental cells. MSC-derived EVs have anti-inflammatory, anti-apoptotic as well as pro-regenerative activities. Research on EVs has gained considerable attention as they are a potential cell-free therapy with lower immunogenicity and easier management than whole cells. MSC-derived EVs can rescue the pathogenetic phenotypes of chondrocytes and exert a protective effect in animal models of rheumatic disease. To facilitate the therapeutic use of EVs, appropriate cell sources for the production of EVs with the desired biological effects in each disease should be identified. Production and isolation of EVs should be optimized, and pre-isolation and post-isolation modifications should be considered to maximize the disease-modifying potential of the EVs.

Advances in extracellular vesicle functionalization strategies for tissue regeneration

Extracellular vesicles (EVs) are nano-scale vesicles derived by cell secretion with unique advantages such as promoting cell proliferation, anti-inflammation, promoting blood vessels and regulating cell differentiation, which benefit their wide applications in regenerative medicine. However, the in vivo therapeutic effect of EVs still greatly restricted by several obstacles, including the off-targetability, rapid blood clearance, and undesired release. To address these issues, biomedical engineering techniques are vastly explored. This review summarizes different strategies to enhance EV functions from the perspective of drug loading, modification, and combination of biomaterials, and emphatically introduces the latest developments of functionalized EV-loaded biomaterials in different diseases, including cardio-vascular system diseases, osteochondral disorders, wound healing, nerve injuries. Challenges and future directions of EVs are also discussed.

Xeno-free cultured mesenchymal stromal cells release extracellular vesicles with a "therapeutic" miRNA cargo ameliorating cartilage inflammation in vitro

Rationale: Mesenchymal stromal cells (MSCs)-derived extracellular vesicles (EVs) emerged as an innovative strategy for the treatment of chronic disorders such as osteoarthritis (OA). Biological activity of EVs is generally driven by their cargo, which might be influenced by microenvironment. Therefore, pre-conditioning strategies, including modifications in culture conditions or oxygen tension could directly impact on MSCs paracrine activity. In this study we selected an appropriate preconditioning system to induce cells to perform the most suitable therapeutic response by EV-encapsulated bioactive factors. Methods: A xeno-free supplement (XFS) was used for isolation and expansion of MSCs and compared to conventional fetal bovine serum (FBS) culture. Bone Marrow-derived MSCs (BMSCs) were pre-conditioned under normoxia (20% O2) or under hypoxia (1% O2) and EVs production was evaluated. Anti-OA activity was evaluated by using an in vitro inflammatory model. miRNA content was also explored, to select putative miRNA that could be involved in a biological function. Results: Modulation of IL-6, IL-8, COX-2 and PGE2 was evaluated on hACs simultaneously treated with IL-1α and BMSC-derived EVs. FBS-sEVs exerted a blunt inhibitory effect, while a strong anti-inflammatory outcome was achieved by XFS-sEVs. Interestingly, in both cases hypoxia pre-conditioning allowed to increase EVs effectiveness. Analysis of miRNA content showed the upregulation in XFS-hBMSC-derived EVs of miRNA known to have a chondroprotective role, such as let-7b-5p, miR-17, miR-145, miR-21-5p, miR-214-3p, miR-30b-5p, miR-30c-5p. Activated pathways and target genes were investigated in silico and upregulated miRNAs functionally validated in target cells. MiR-145 and miR-214 were found to protect chondrocytes from IL-1α-induced inflammation and to reduce production of pro-inflammatory cytokines. Conclusions: XFS medium was found to be suitable for isolation and expansion of MSCs, secreting EVs with a therapeutic cargo. The application of cells cultured exclusively in XFS overcomes issues of safety associated with serum-containing media and makes ready-to-use clinical therapies more accessible.

Breakthrough of extracellular vesicles in pathogenesis, diagnosis and treatment of osteoarthritis

Osteoarthritis (OA) is a highly prevalent whole-joint disease that causes disability and pain and affects a patient's quality of life. However, currently, there is a lack of effective early diagnosis and treatment. Although stem cells can promote cartilage repair and treat OA, problems such as immune rejection and tumorigenicity persist. Extracellular vesicles (EVs) can transmit genetic information from donor cells and mediate intercellular communication, which is considered a functional paracrine factor of stem cells. Increasing evidences suggest that EVs may play an essential and complex role in the pathogenesis, diagnosis, and treatment of OA. Here, we introduced the role of EVs in OA progression by influencing inflammation, metabolism, and aging. Next, we discussed EVs from the blood, synovial fluid, and joint-related cells for diagnosis. Moreover, we outlined the potential of modified and unmodified EVs and their combination with biomaterials for OA therapy. Finally, we discuss the deficiencies and put forward the prospects and challenges related to the application of EVs in the field of OA.

Inflammatory priming with IL-1β promotes the immunomodulatory behavior of adipose derived stem cells

Inflammatory processes contribute to osteoarthritis (OA) severity and progression. Mesenchymal stem cells, particularly those derived from adipose tissue (ASCs), are able to sense and control the inflammatory environment. This immunomodulatory potential can be boosted by different priming strategies based on inflammatory stimulation. The aim of the present study is to investigate the transcriptional modulation of a huge panel of genes and functionally verify the predicted immunomodulatory ability of ASCs after interleukin one beta (IL-1β) priming. ASCs were isolated from adipose tissue obtained from three donors and expanded. After stimulation with 1 ng/ml of IL-1β for 48 h, cells were collected for gene array and functional tests. Pooled cells from three donors were used for RNA extraction and gene array analysis. Gene Ontology (GO) enrichment analysis and Gene Set Enrichment Analysis (GSEA) were performed to assess the involvement of the modulated genes after priming in specific biological processes and pathways. Functional co-culture tests of ASCs with T cells and macrophages were performed to assess the ability of primed ASCs to modulate immune cell phenotype. Among the overall genes analyzed in the gene array, about the 18% were up- or down-regulated in ASCs after IL-1β priming. GO enrichment analysis of up- or down-regulated genes in ASCs after IL-1β priming allowed identifying specific pathways involved in the modulation of inflammation and extracellular matrix remodeling. The main processes enriched according to the GSEA are related to the inflammatory response and cell proliferative processes. Functional tests on immune cells showed that primed and non-primed ASCs induced a decrease in the CD3+ T lymphocytes survival rate and an anti-inflammatory macrophage polarization. In conclusion, IL-1β priming represents a tailored strategy to enhance the ability of ASCs to direct macrophages towards an anti-inflammatory phenotype and, consequently, improve the efficacy of ASCs in counteracting the OA inflammatory component.

Immunomodulatory potential of secretome from cartilage cells and mesenchymal stromal cells in an arthritic context: From predictive fiction toward reality

The purpose of the present study is to predict by bioinformatics the activity of the extracellular vesicle (EV)-embedded micro RNA (miRNAs) secreted by cartilage cells (CCs), adipose tissue-derived- (ASCs), and bone marrow-derived stem cells (BMSCs) and verify their immunomodulatory potential supporting our bioinformatics findings to optimize the autologous cell-based therapeutic strategies for osteoarthritis (OA) management. Cells were isolated from surgical waste tissues of three patients who underwent total hip replacement, expanded and the EVs were collected. The expression of EV-embedded miRNA was evaluated with the QuantStudio 12 K Flex OpenArray^® platform. Mientournet and ingenuity pathway analysis (IPA) were used for validated target prediction analysis and to identify miRNAs involved in OA and inflammation. Cells shared the expression of 325 miRNAs embedded in EVs and differed for the expression of a small number of them. Mienturnet revealed no results for miRNAs selectively expressed by ASCs, whereas miRNA expressed by CCs and BMSCs were putatively involved in the modulation of cell cycle, senescence, apoptosis, Wingless and Int-1 (Wnt), transforming growth factor beta (TGFβ), vascular endothelial growth factor (VEGF), Notch, Hippo, tumor necrosis factor alpha (TNFα), interleukin 1 beta (IL-1β), insulin like growth factor 1 (IGF-1), RUNX family transcription factor 2 (RUNX2), and endochondral ossification pathways. Cartilage homeostasis, macrophages and T cells activity and inflammatory mediators were identified by IPA as targets of the miRNAs found in all the cell populations. Co-culture tests on macrophages and T cells confirmed the immuno-modulatory ability of CCs, ASCs, and BMSCs. The study findings support the rationale behind the use of cell-based therapy for the treatment of OA.

Bone marrow aspirate concentrate quality is affected by age and harvest site

PURPOSE

To compare the number and properties of bone marrow stromal cells (BMSCs) collected from bone marrow aspirate concentrate (BMAC) obtained from different harvest sites and from patients of different ages.

METHODS

BMAC was obtained from two groups of patients based on age (n = 10 per group): 19.0 ± 2.7 years for the younger and 56.8 ± 12.5 for the older group. In the latter, BMAC was obtained from both iliac crest and proximal tibia for a donor-matched analysis. Mononucleated cell count and CFU-F assay were performed, together with phenotype characterization of BMSCs from iliac crest and proximal tibia, the study of chondrogenic and osteogenic differentiation capacity, histological staining and spectrophotometric quantification, and the analysis of mRNAs expression.

RESULTS

Cells derived from iliac crest and proximal tibia showed the same phenotypic pattern at flow cytometry, as well as similar chondrogenic and osteogenic potential. However, a significantly higher number of mononuclear cells per ml was observed in younger patients (3.8 ± 1.8 × 10⁷) compared to older patients (1.2 ± 0.8 × 10⁷) (p < 0.0005). The latter yield, obtained from the iliac crest, was significantly higher than resulting from the BMAC harvested from the proximal tibia in the same group of patients (0.3 ± 0.2 × 10⁷, p < 0.0005). This result was confirmed by the CFU-F analysis at day 10 (15.9 ± 19.4 vs 0.6 ± 1.0, p = 0.001) and day-20 (21.7 ± 23.0 vs 2.9 ± 4.2, p = 0.006).

CONCLUSION

Harvest site and age can affect the quality of BMAC. BMSCs obtained from iliac crest and proximal tibia present comparable mesenchymal markers expression as well as osteogenic and chondrogenic differentiation potential, but iliac crest BMAC presents a four times higher number of mononucleated cells with significantly higher clonogenic capacity compared to the tibia. BMAC of younger patients also had a three-time higher number of mononucleated cells. The identification of BMAC characteristics could help to optimize its preparation and to identify the most suitable indications for this orthobiologic treatment in the clinical practice.

The potential therapeutic role of extracellular vesicles in osteoarthritis

Osteoarthritis (OA) is a worldwide and disabling disease, which cause severe pain and heavy socioeconomic burden. However, pharmacologic or surgical therapies cannot mitigate OA progression. Mesenchymal stem cells (MSCs) therapy has emerged as potential approach for OA treatment, while the immunogenicity and ethical audit of cell therapy are unavoidable. Compared with stem cell strategy, EVs induce less immunological rejection, and they are more stable for storage and in vivo application. MSC-EVs-based therapy possesses great potential in regulating inflammation and promoting cartilage matrix reconstruction in OA treatment. To enhance the therapeutic effect, delivery efficiency, tissue specificity and safety, EVs can be engineered via different modification strategies. Here, the application of MSC-EVs in OA treatment and the potential underlying mechanism were summarized. Moreover, EV modification strategies including indirect MSC modification and direct EV modification were reviewed.

The Wnt signaling cascade in the pathogenesis of osteoarthritis and related promising treatment strategies

Osteoarthritis (OA) is the most prevalent joint disease, characterized by the degradation of articular cartilage, synovial inflammation, and changes in periarticular and subchondral bone. Recent studies have reported that Wnt signaling cascades play an important role in the development, growth, and homeostasis of joints. The Wnt signaling cascade should be tightly regulated to maintain the homeostasis of cartilage in either the over-activation or the suppression of Wnt/β-catenin, as this could lead to OA. This review summarizes the role and mechanism of canonical Wnt cascade and noncanonical Wnt cascade experiments in vivo and in vitro. The Wnt cascade is controlled by several agonists and antagonists in the extracellular medium and the cytoplasm. These antagonists and agonists serve as key molecules in drug intervention into the Wnt pathway and may provide potential approaches for the treatment of OA. However, the complexity of the Wnt signaling cascade and the pharmaceutical effects on its mechanism are still not fully understood, which forces us to conduct further research and develop efficient therapeutic approaches to treat OA.

Small Extracellular Vesicles from Inflamed Adipose Derived Stromal Cells Enhance the NF-κB-Dependent Inflammatory/Catabolic Environment of Osteoarthritis

The last decade has seen exponentially growing efforts to exploit the effects of adipose derived stromal cells (ADSC) in the treatment of a wide range of chronic degenerative diseases, including osteoarthritis (OA), the most prevalent joint disorder. In the perspective of developing a cell-free advanced therapy medicinal product, a focus has been recently addressed to the ADSC secretome that lends itself to an allogeneic use and can be further dissected for the selective purification of small extracellular vesicles (sEVs). sEVs can act as “biological drug carriers” to transfer information that mirror the pathophysiology of the providing cells. This is important in the clinical perspective where many OA patients are also affected by the metabolic syndrome (MetS). ADSC from MetS OA patients are dysfunctional and “inflammatory” primed within the adipose tissue. To mimic this condition, we exposed ADSC to IL-1β, and then we investigated the effects of the isolated sEVs on chondrocytes and synoviocytes, either cultured separately or in co-culture, to tease out the effects of these “IL-1β primed sEVs” on gene and protein expression of major inflammatory and catabolic OA markers. In comparison with sEVs isolated from unstimulated ADSC, the IL-1β primed sEVs were able to propagate NF-κB activation in bystander joint cells. The effects were more prominent on synoviocytes, possibly because of a higher expression of binding molecules such as CD44. These findings call upon a careful characterization of the “inflammatory fingerprint” of ADSC to avoid the transfer of an unwanted message as well as the development of in vitro “preconditioning” strategies able to rescue the antiinflammatory/anticatabolic potential of ADSC-derived sEVs.

Joint Tissue Protective and Immune-Modulating miRNA Landscape of Mesenchymal Stromal Cell-Derived Extracellular Vesicles under Different Osteoarthritis-Mimicking Conditions

In regenerative medicine related to orthopedic conditions, mesenchymal stromal cells (MSCs) and their extracellular vesicles (EVs) have been proposed as innovative clinical options. The definition of EV-shuttled signals and their modulation under orthopedic settings, such as osteoarthritis (OA), is crucial for MSC-related research, both for basic science and for use in clinical settings, either as therapeutics or as producers of cell-free products such as EVs or secretome. The objective of this work is to compare the literature available on high-throughput EV-miRNA data obtained from adipose-derived MSCs (ASCs) in standard conditions or cultured in high levels of IFNγ, low-level inflammatory conditions mimicking OA synovial fluid (SF), and OA-SF. The first result was that both IFNγ and low-level inflammatory treatment led to an increase, whereas SF led to a reduction in EV release. Second, more than 200 EV-miRNAs were found to be shared across the different conditions. After a bioinformatics search through experimentally validated and OA-related targets, pathways and tissues, several miRNAs resulted in the restoration of cartilage and synovium stability and the homeostasis of inflammatory cells, including macrophages, promoting their switch towards an M2 anti-inflammatory phenotype. Third, IFNγ and especially SF culturing were able to modulate the overall EV-miRNA fingerprint, although the main molecular messages related to OA resulted conserved between treatments with the majority of modulations within 2-fold range. In conclusion, ASC EV-miRNAs may be modulated in their overall landscape by OA-related culturing conditions albeit resulted largely stable in their specific OA-protective signals allowing for a faster clinical translation of these new cell-free therapies for joint diseases.

Visualization of intracellular lipid metabolism in brown adipocytes by time-lapse ultra-multiplex CARS microspectroscopy with an onstage incubator

We visualized a dynamic process of fatty acid uptake of brown adipocytes using a time-lapse ultra-broadband multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopic imaging system with an onstage incubator. Combined with the deuterium labeling technique, the intracellular uptake of saturated fatty acids was traced up to 9 h, a substantial advance over the initial multiplex CARS system, with an analysis time of 80 min. Characteristic metabolic activities of brown adipocytes, such as resistance to lipid saturation, were elucidated, supporting the utility of the newly developed system.