Biology subjects

Mahdad, R.

Publications and source records attributed to Mahdad, R..

3 recordsLinked to original sources

bioRxiv2026

Spatial transcriptomics defines the mechanisms of hiPSC derived stem cell mediated repair in human articular cartilage

We here determined therapeutic efficacy and mode-of-action of human induced pluripotent-derived therapeutic stem cells (hiMSCs) across in vivo mouse and ex vivo human osteoarthritis models. hiMSC treatment in DMM-mice significantly reduced OARSI damage scores, which was affirmed by a decrease in the catabolic marker Mmp13 and an increase in the anabolic marker Col2. These treatment effects appeared, irrespective of modifying factors such as xeno-free media or thermosensitive hydrogel carrier. Subsequently treatment of hiMSC+gel in human osteoarthritic cartilage explants showed a transcriptome-wide significant activation of the cholesterol and sterol synthesis pathways marked by genes such as MVD, DHCR7, MSMO1, FABP3. Additionally, we showed that these changes alleviated OA-associated imbalances of the cellular Zinc-ion homeostasis pathways, represented by genes such as MT1F, MT1G, MT1H and SLC30A1. Spatial transcriptomics then sensitively captured that hiMSC+gel treatment evoked, specifically at the superficial cartilage layer, a consistent upregulation of healthy chondrocyte markers such as CHAD, ACAN, FRZB, and SOX9, alongside a suppression of catabolic and inflammatory mediators such as SERPINE1, SPP1, MMP13, ADAMTS5. Our findings link therapeutic outcomes of hiMSC treatment to precise spatially resolved molecular changes in human tissue, that would otherwise be obscured by heterogeneous cell populations. Collectively our study highlighted that hiPSC-derived stem cell therapy (hiMSCs) could provide a scalable off-the-shelf solution to treat osteoarthritis, with strong prospects for clinical applications in the near future.

developmental biology↗

bioRxiv2026

Dynamic suspension culture enhances scalable maturation of hiPSC-derived cartilage organoids for regenerative medicine

BackgroundCartilage tissue engineering requires scalable culture strategies to produce high-quality organoids. Human induced pluripotent stem cells (hiPSCs) provide a renewable source of chondrogenic cells. However, conventional static 3D culture limits tissue maturation, reproducibility, and scalability. Dynamic culture systems may help overcome these limitations, although their application for hiPSC-derived cartilage maturation remains poorly explored. MethodsIn this study, we established and validated a dynamic suspension bioreactor culture platform (CERO, OLS) for scalable maturation of hiPSC-derived chondroprogenitor cells (hiCPCs) into cartilage organoids populated by biomimetic human induced chondrocytes (hiCHOs). Key culture parameters, including aggregate preparation strategy, agitation speed, and maturation duration, were systematically evaluated. Cartilage maturation under dynamic and conventional static culture conditions was assessed by histology and immunohistochemistry, biochemical assays, organoid size measurements, and gene expression (RT-qPCR). In addition, the functional integration of optimized organoids was evaluated in a human osteochondral explant model. ResultsPre-formed manually picked hiCPC aggregates showed improved cartilage formation compared with single-cell seeding or pelleted aggregates in the bioreactor. Dynamic suspension culture promoted increased construct growth, enhanced ECM deposition, and a more favourable cartilage-associated molecular phenotype compared with static culture. HiCHO organoids matured under dynamic suspension conditions displayed increased sulphated glycosaminoglycan and proteoglycan deposition together with higher expression of cartilage-associated genes ACAN, COMP, MGP, and COL2A1. Although prolonged static maturation alone supported continued cartilage development, introducing dynamic suspension culture during later maturation stages further reinforced favourable molecular and matrix-associated features. Importantly, hiCHO organoids generated under optimized dynamic culture conditions successfully filled human cartilage defects and established matrix continuity with surrounding native tissue in a human osteochondral ex vivo explant model. ConclusionsThis study shows that dynamic suspension culture is an effective and scalable strategy for maturation of hiPSC-derived cartilage organoids. Consequently, this approach supports reproducible neo-cartilage production and allows functional testing in human tissue models. These findings support the use of dynamic culture systems for cartilage repair and in vitro/ex vivo cartilage research.

Cell Biology↗

bioRxiv2025

Evaluating the Therapeutic Efficacy of Iopanoic Acid in a DMM-Induced Osteoarthritis Mouse Model and Osteochondral Lesioned Human Explants

ObjectiveTo evaluate the therapeutic potential of iopanoic acid (IOP), a thyroid hormone pathway inhibitor, in preserving cartilage and bone integrity in osteoarthritis (OA), using in vivo and ex vivo tissue models. DesignIn the DMM mouse model, IOP was administered through intra-articular (i.a.) injection, either alone or combined with a thermosensitive hydrogel to enable sustained release. Histological analyses included Safranin O/Fast Green staining and OARSI scoring. Immunohistochemistry was performed for COL2, MMP13, and CCDC80 to evaluate anabolic, catabolic, and hypertrophic markers. Micro-CT assessed subchondral bone changes. In the ex vivo studies, IOP was applied to lesioned human osteochondral OA explants. Matrix degradation and repair were evaluated by sulfated glycosaminoglycan (sGAG) release, Mankin histology scores, and RT-qPCR for cartilage matrix genes. ResultsAdministration of IOP significantly reduced cartilage degeneration in DMM mice (P [≤] 1.0x10-4), characterized by increased COL2, and decreased MMP13 and CCDC80 expression. Notably, IOP also prevented pathological subchondral bone thickening. In human explants, IOP treatment led to a significant reduction in sGAG release compared to untreated explants on day 6 of the IOP treatment. Moreover, Mankin scores were significantly improved in IOP-treated compared to untreated explants, indicating reduced cartilage degradation. ConclusionIOP demonstrates strong chondroprotective effects, reducing cartilage degradation and promoting repair in OA models. Its combination with a thermosensitive hydrogel amplifies therapeutic potential, offering a promising strategy for OA treatment. Next steps are to optimize delivery and validate early molecular effects.

molecular biology↗