Biology subjects

Sayedipour, S.

Publications and source records attributed to Sayedipour, S..

6 recordsLinked to original sources

bioRxiv2026

The Leiden ex vivo human growth plate model in severe tall stature: a proof-of-concept study

Background: Viable human growth plate (GP) tissue is rarely available for translational research, limiting direct investigation of human longitudinal bone growth and pediatric growth disorders. In this proof-of-concept study, we aimed to determine feasibility to establish a clinically integrated ex vivo human growth plate model using tissue obtained during routine percutaneous epiphysiodesis (PE) procedures in adolescents treated for extreme tall stature or leg length difference due to trauma. Methods: Growth plate tissue and cells were collected during PE and processed using protocols adapted from established methods of human osteoarthritic cartilage collection within the RAAK study. Collected tissues and three-dimensional cartilage pellets generated from isolated cells were assessed by histology. Proliferation of GP-derived chondrocytes was compared with osteoarthritis-derived articular chondrocytes. Results: Across consecutive surgical procedures, viable GP tissue could be obtained reproducibly including the node of Ranvier, with only few samples failing to yield cells and no contamination. Isolated GP chondrocytes expanded successfully in two-dimensional culture and showed a stronger early proliferative response compared with RAAK-derived chondrocytes. In addition, GP-derived cells formed three-dimensional organoids and histology confirmed cartilage-like matrix deposition supporting their capacity to generate neo-cartilage tissue in vitro. Conclusion: This study demonstrates feasibility to obtain, culture, and functionally assess viable human growth plate tissue from routine PE surgery. As such, the Leiden ex vivo human growth plate model provides a unique platform to study local mechanisms of endochondral bone growth, link genetic determinants of height to functional growth plate biology, and support future therapeutic research in pediatric growth disorders.

developmental biology↗

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

Therapeutic efficacy of hiMSC-derived Extracellular Vesicles from Serum-containing and Xeno-free media for osteoarthritis treatment

BackgroundExtracellular vesicles derived from human induced mesenchymal stromal cells (hiEVs) constitute a promising cell-free therapeutic option for osteoarthritis. To allow translation to the clinic we evaluated the therapeutic effects of hiEVs for osteoarthritis treatment. Specifically, we assessed the efficacy of hiEVs collected from serum-containing and serum-free, PurStem (PS), media in an OA mice model. MethodshiEVs were administered with or without hydrogel via intra-articular (i.a.) injection in a destabilization of the medial meniscus (DMM) mouse model. Fluorescence imaging was used to monitor the retention of IR780-labeled hiEVs in the joint cavity. The therapeutic effects were evaluated by analyzing damage scores as well as catabolic and anabolic markers, including Mmp13 and Col2 expression, in joint tissues. ResultsFluorescence imaging confirmed that hiEVs remained localized at the injection site without systemic migration. HiEVs demonstrated significant protective effects against joint tissue degeneration in the DMM mouse OA model, as evidenced by reduced damage scores, decreased Mmp13 expression, and increased anabolic processes (Col2 expression). The hydrogel alone also exerted beneficial therapeutic effects, including reduced damage scores, increased Col2 expression, and reduced Mmp13 levels; however, these effects were notably smaller than those achieved with hiEV treatment while it was independent of the medium used for hiEV collection. ConclusionsTogether, our findings demonstrate that hiEVs from xeno-free conditions effectively prevent cartilage degradation and promote its repair. This paves the way for future clinical translation of hiEV-based therapies as a safe, scalable, and effective approach to treat osteoarthritis.

developmental 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↗

bioRxiv2025

Advancing Therapeutic Solutions: Poloxamer-based Thermosensitive Injectable Hydrogels containing a Self-assembling Peptide for In situ Gelation in an Osteoarthritis Murine Model

This study presents the development and characterization of a novel thermosensitive injectable hydrogel designed to enhance the biomechanical properties of poloxamer 407 (P407) through the incorporation of a self-assembling peptide. The primary objective was to engineer a formulation that rapidly gels following intra-articular (i.a.) injection, exhibits improved mechanical strength, and enables sustained release of embedded therapeutic cargo. Gelation time assays demonstrated that the P407-peptide formulation solidified more quickly than P407 alone at equivalent concentrations. Rheological analysis revealed a 1.5 kPa increase in storage modulus in the hybrid hydrogel, confirming improved mechanical integrity. In vitro biocompatibility was assessed using human chondrocytes, with MTS assays and LIVE/DEAD staining indicating no cytotoxicity across tested concentrations. To evaluate in vivo applicability, a near-infrared fluorescent (NIRF) dye was incorporated into the hydrogel and injected intra-articularly into an osteoarthritis (OA) mouse model. The labeled formulation allowed for successful tracking and demonstrated localized gelation, supporting its suitability for site-specific, sustained delivery. Overall, the P407-peptide hydrogel offers a promising platform for i.a. therapeutic applications, combining injectability, rapid thermoresponsive gelation, mechanical reinforcement, and controlled release behavior, making it well-suited for regenerative medicine and OA treatment.

biochemistry↗