Speaker
Description
Introduction
Osteoarthritis (OA) is a degenerative disease affecting osteochondral (OC) tissue, leading to pain and joint dysfunction. Current treatments are often limited by availability, efficacy, and cost, highlighting the need for innovative therapeutic approaches. To address this challenge, we propose a novel tool EndoFLight, an advanced in situ 3D bioprinting platform designed for minimally invasive regeneration of large OC lesions (Figure 1a). This system integrates multi-material, multiscale bioprinting by combining bioink extrusion through standard arthroscopic instruments with filamented light (FLight) printing1 to enable precise deposition and crosslinking of cell-laden photo-resins directly at the injury site.
This study presents the formulation and characterization of photo-resins for EndoFLight technology, which aims to provide a clinically translatable solution for osteochondral tissue regeneration in OA treatment.
Methods
Photo-resins were developed using gelatin methacrylamide (GelMA, X-pure grade, Rousselot), either alone or blended with methacrylated hyaluronic acid (HAMA, LifeCore Biomedical) or hydroxyapatite (HAp, CAM Bioceramics). These formulations were designed to support cartilage and bone regeneration, respectively, with lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) serving as the photo-initiator. The selection of X-pure grade GelMA was motivated by its GMP-compliant production and ultra-low endotoxin content, ensuring its suitability for future clinical applications.
Rheological properties of the photo-resins were analyzed using an Anton Paar MCR 702 rheometer to assess their photo-crosslinking characteristics. The resins were exposed to blue light (400–500 nm, 25 mW/cm²) for 10 minutes at 37°C while simultaneously monitoring the storage and loss moduli. Finally, biocompatibility was evaluated in vitro via LIVE/DEADTM assays. Analyses were performed on crosslinked cell-laden photo-resins and cell monolayers to which uncrosslinked photo-resin droplets were added, with the latter undergoing crosslinking afterwards.
Results
The formulated GelMA/HAMA and GelMA/HAp blends were optically transparent, essential for precise bioprinting via EndoFLight. Photo-rheology tests confirmed their rapid photo-crosslinking behavior, with all resins reaching a stable plateau storage modulus of 4–8 kPa (Figure 1b), which is within an optimal range for cartilage and bone tissue formation, as supported by previous studies.1,2 While HAMA incorporation led to a slight increase in storage modulus, no statistically significant difference were found between the blends and pure GelMA solutions (Figure 1c). Preliminary viability tests indicate that the photo-resins are biocompatible both before and after photo-crosslinking.
Discussion
This project aims to address an unmet clinical need through an innovative, one-step technology to accurately reconstruct the complex architecture of articular cartilage directly in the OC lesion, thereby promoting in situ regeneration. Future research will focus on optimizing the bioinks for the EndoFLight setup, followed by validation of the system through in vitro, ex-vivo and in vivo studies.
References
[1] Liu, H. et al. (2022), Advanced Materials, 34, 2204301.
[2] Hölzl, K. et al. (2022) Journal of tissue engineering and regenerative medicine, 16, pp.207-222.
[3] Suvarnapathaki, S. et al. (2020) Macromolecular Bioscience, 20, 2000176.
Acknowledgments
Horizon Europe programme is acknowledged for the financial support to LUMINATE project (ID: 101191804)
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