Biology subjects

Boumediene, K.

Publications and source records attributed to Boumediene, K..

5 recordsLinked to original sources

bioRxiv2026

Lyophilized Cell-Secreted Matrix as a Bioactive Substrate for Chondrocyte Expansion and Redifferentiation

Articular cartilage repair is limited by the poor regenerative capacity of chondrocytes and their rapid dedifferentiation during in vitro expansion. This study investigated whether a decellularized and lyophilized cell-secreted matrix (CSM) could function as a bioactive material to regulate cell behavior, promote chondrogenic differentiation, and attenuate or reverse chondrocyte dedifferentiation without exogenous growth factor supplementation. CSM was generated from rabbit auricular perichondrial cells, decellularized, lyophilized, and characterized by histology, biochemical assays, and proteomic analysis. The resulting matrix was enriched in structurally and functionally relevant extracellular matrix proteins, including collagens, fibronectin, fibrillin, proteoglycans, and matricellular regulators, with minimal intracellular contamination and good batch-to-batch reproducibility. Functionally, CSM supported robust adhesion and proliferation of allogeneic and xenogeneic cells. Human articular chondrocytes cultured on CSM exhibited enhanced proliferation, sustained expression of cartilage-specific markers, and preserved type II collagen production over serial passages compared with standard plastic culture. CSM also promoted chondrogenic differentiation of human progenitor cells and partially reversed established chondrocyte dedifferentiation, as evidenced by increased expression of COL2A1, ACAN, SOX9, and COMP, with reduced COL1 expression and no induction of hypertrophic markers. These findings demonstrate that lyophilized CSM is a stable, off-the-shelf biomaterial capable of directing chondrocyte fate through intrinsic matrix-derived cues, highlighting its potential for cartilage tissue engineering and cell manufacturing applications.

bioengineering↗

bioRxiv2025

Systemic immune alterations in a murine experimental model of osteoarthritis

Osteoarthritis (OA) is accompanied by an inflamed synovium containing macrophages, dendritic cells, T and B lymphocytes. Macrophages predominate and drive cytokine-mediated cartilage catabolism, while T cells and B cells, though fewer, may shape chronic adaptive responses. However, systemic immune contributions, particularly within peripheral lymphoid organs such as the spleen, remain poorly characterized. Our study aims to profile systemic immune changes in experimental OA induced by injection of mono-iodoacetate (MIA) in mouse paw. At day 56 post-OA induction, analysis of splenocytes showed that macrophages and conventional dendritic cells (cDC1 and cDC2) displayed a significant downregulation of MHCII expression, suggesting a negative feedback mechanism that limits chronic T cell activation. OA is also associated with an increase in total DCs including mainly MHCII negative tolerogenic DCs. Notably, while the proportion of CD11b- tolerogenic DCs was reduced, CD11blow tolerogenic DCs markedly expanded in OA animals. Expression level of the CD11b integrin was upregulated on macrophages and cDC2 in MIA-induced OA mice potentially facilitating their adhesion and migration toward inflamed joint. OA mice showed a significant reduction in total splenic leukocytes, primarily due to a loss of B cells, while total T cell numbers remained stable. However, T cell composition shifted: CD4+ T cells including activated and regulatory subsets decreased, whereas activated CD8+ T cells increased. This indicates a systemic imbalance favoring cytotoxic over regulatory immune activity, possibly linked to chronic immune stress or redistribution of lymphocytes to inflamed joint. In conclusion, our data reveals that chronic OA induces a coordinated remodeling of systemic innate and adaptive immunity. These systemic immune dysregulations could reveal new biomarkers or therapeutic targets.

physiology↗

bioRxiv2025

Epigenetic Regulation of Chondrogenesis: JMJD3 and UTX as Key Targets for Gene-Modified Mesenchymal Stem Cell Therapy in Cartilage Tissue Engineering

Osteoarthritis is a major cause of disability in older adults, and among the promising therapeutic strategies, cartilage tissue engineering shows great potential. Histone methylation plays a critical role in cartilage development, making it an appealing target for improving cartilage engineering protocols. In this study, we evaluated the roles of JMJD3 (KDM6B) and UTX (KDM6A), both demethylases of histone H3 at lysine 27 (H3K27), in chondrogenesis and their application in gene-modified mesenchymal stem cell therapy for cartilage tissue engineering. Using high-throughput analyses such as ChIP-Seq and whole-transcriptome microarray, we explored the functions of JMJD3 and UTX in human bone marrow-derived mesenchymal stem cells (hBM-MSC) undergoing chondrogenesis. We investigated the impact of inhibiting JMJD3 and UTX with the pharmacological inhibitor GSK-J4 or using siRNA. Additionally, the effects of transiently transfecting JMJD3 or UTX expression vectors were assessed both in vitro and in vivo, following the implantation of hBM-MSC embedded in alginate in nude mice. Our findings revealed that JMJD3 is specifically upregulated during chondrogenesis in hBM-MSC, and is crucial for this differentiation process. In contrast, UTX was found to be dispensable for chondrogenesis. Nevertheless, both JMJD3 and UTX share the ability to demethylate similar gene loci, thereby promoting the expression of chondrogenic signature genes, which suggests functional redundancy. Notably, the genes encoding these H3K27me3 demethylases emerge as strong candidates for enhancing gene-modified mesenchymal stem cell therapy for cartilage tissue engineering, as their overexpression during chondrogenesis significantly increased the formation of thicker cartilage discs enriched with type II collagen. In conclusion, this study provides important insights into the epigenetic regulation of chondrogenesis, especially regarding the role of H3K27me3 demethylases. We demonstrate that, although JMJD3 and UTX have overlapping targets, only JMJD3 is critical for the chondrogenesis process. Additionally, the findings emphasize the potential of transient JMJD3 transduction, along with a lesser emphasis on UTX, as effective strategies for improving gene-modified mesenchymal stem cell therapy in cartilage tissue engineering.

developmental biology↗

bioRxiv2025

Inhibiting EZH2 Alleviates Osteoarthritis and Pain in an Experimental Murine Model Through Modulating Synovial and Macrophage Inflammation, Axon Guidance, and Osteoclastogenesis

Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase responsible for H3K27 trimethylation, has emerged as a potential therapeutic target in osteoarthritis (OA). However, its contribution to the multicellular mechanisms driving joint degeneration and pain remains poorly understood. Here, we investigated the effects of pharmacological EZH2 inhibition in a pain-relevant murine OA model and explored its cellular and molecular consequences across OA-associated cell populations. OA was induced in mice by intra-articular monosodium iodoacetate (MIA) injection followed by local administration of the EZH2 inhibitor EPZ-6438. Joint pathology and pain-related behaviors were assessed by histological and functional analyses. Mechanistic studies were performed in primary human OA fibroblast-like synoviocytes and bone marrow-derived cells using targeted gene expression analyses, proteomics and ChIP-seq approaches. EZH2 inhibition reduced cartilage damage, synovial inflammation and pain-related behavioral alterations in vivo. In OA synoviocytes, EPZ-6438 decreased the expression of inflammatory, catabolic and pain-associated mediators while promoting autophagy-related responses. Proteomic and ChIP-seq analyses revealed EZH2-dependent regulation of inflammatory pathways, cellular homeostasis and neuronal-associated processes, including axon guidance-related pathways. ChIP-seq further identified inflammation-dependent EZH2 recruitment to promoters of neurodevelopmental regulators, including PAX6, suggesting a potential contribution of EZH2 to neuronal-associated mechanisms in OA. In addition, EZH2 inhibition reduced macrophage inflammatory activation and osteoclast differentiation. Together, these findings identify EZH2 as a candidate epigenetic regulator linking inflammatory, neuroimmune and osteoimmune pathways across the osteoarthritic joint. Targeting EZH2 may represent a therapeutic strategy to simultaneously modulate joint inflammation, remodeling and pain-associated pathways.

physiology↗

bioRxiv2024

Exploring Adenosine Analogues for Chondrosarcoma Therapy: In Vitro and In Vivo Insights

Chondrosarcoma (CS) is described as resistant to conventional chemotherapy and radiotherapy. The development of new therapeutic approaches is necessary. The aim of the present study is to validate the use of adenosine analogues as a new therapeutic strategy in the treatment of CS. Five adenosine analogues (aristeromycin, cladribine, clofarabine, formycin, and pentostatin) were evaluated in vitro on several chondrosarcoma cell lines using both 2D cultures and 3D alginate bead models. Cell viability was assessed using Acridine Orange and DAPI staining, or ATP assay. Apoptosis was measured via Annexin V and Propidium Iodide staining, while cell cycle progression was analyzed with DAPI staining. The most promising compounds were further tested in vivo using a xenograft chondrosarcoma model in nude mice. Results showed that four analogues (aristeromycin, formycin, cladribine, and clofarabine) significantly reduced cell viability in 2D cell cultures. Of these, cladribine and clofarabine demonstrated potent efficacy in both 2D and 3D models by inducing apoptosis. Cladribine was further found to induce cell cycle arrest, leading to apoptosis-mediated cell death. In vivo, both cladribine and clofarabine exhibited substantial antitumor effects in a xenograft model. In conclusion, cladribine and clofarabine, which are already approved for clinical use in leukemia and multiple sclerosis, show promise as potential candidates for chondrosarcoma treatment. Their efficacy in preclinical models suggests these molecules could be repurposed for Phase II clinical trials in CS patients.

cancer biology↗