Speaker
Description
A Modular Endoscopic Projection System for Spatially Patterned Photocrosslinking in Cartilage Repair
Theofanis Stampoultzis1, Parth Chansoria1, Marco Raffo2, Amedeo Franco Bonatti2, Giovanni Vozzi2,3, Marcy Zenobi-Wong1
1Tissue Engineering and Biofabrication Lab, ETH Zurich
2Research Center "E. Piaggio", University of Pisa, Pisa, Italy
3Department of Information Engineering, University of Pisa, Pisa, Italy
Correspondence: marcy.zenobi@hest.ethz.ch
Introduction:
In situ bioprinting enables on-site fabrication of biomaterials directly within defect sites, offering unique advantages for cartilage repair. However, achieving spatial precision and surgical adaptability remains a significant challenge. This study presents a fiber-based light projection system, allowing real-time, patterned photocrosslinking of hydrogels within confined joint spaces and is compatible with standard endoscopes.
Methods:
A 405 nm laser was modulated using a digital micromirror device (DMD) and passed through custom lens assemblies and a beam homogenizer to ensure uniform pattern delivery. The structured light was transmitted through a coherent image guide fiber with minimal resolution loss. This fiber could be used alone or coupled externally to standard 0° or 30° arthroscopes. Light behavior was characterized at working distances of 0.5–2 cm using geometric patterns. To assess biological performance, GelMA hydrogels laden with human chondrocytes were crosslinked into defined architectures and cultured in vitro.
Results:
Structured light crosslinking enabled the fabrication of well-aligned microarchitectures within GelMA-Rhodamine hydrogels. Orientation analysis revealed filamentous features with high directional fidelity, as confirmed by peak alignment at –7.5° in OrientationJ. Cell-laden constructs maintained viability and exhibited robust extracellular matrix production over 54 days. Histological staining (Safranin O, Collagen II) revealed cartilage-like matrix deposition.
Discussion:
This platform offers a compact, spatially precise photocrosslinking strategy compatible with confined anatomical spaces. By enabling the fabrication of structured, cell-laden constructs that support cartilage-like tissue development in vitro, this approach may serve as a foundational tool for minimally invasive bioprinting strategies. The system’s modularity allows future adaptation toward intraoperative or image-guided procedures, without compromising biological performance.
Acknowledgements:
M.Z.W. acknowledges funding from the European Union call HORIZON-HLTH-2024-TOOL-11-02 (acronym: LUMINATE, number: 101191804) and from the Swiss State Secretariat for Education, Research and Innovation (SERI).
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