Bio-inspired multizonal protein scaffolds as novel cartilage model system

• Applicants: Professorin Dr. Dorothea Brüggemann; Professorin Dr. Andrea Hoffmann; Professor Dr. Oliver Plettenburg
• Subject Area: Biomaterials
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 542992440

The increasing life expectancy leads to high patient numbers with cartilage defects. This requires new strategies in cartilage tissue engineering. Both collagen as a major component of cartilage and fibrinogen hold great potential for cartilage regeneration and chondrogenic differentiation of mesenchymal stem cells (MSCs), particularly with nanofibrous scaffold topographies that closely mimic the interconnected fiber network of native cartilage. However, native cartilage has a complex architecture consisting of three zones with varying fiber orientation. Mimicking these multizonal fiber networks is a major challenge in cartilage tissue engineering. Therefore, we here propose a new concept to mimic the architecture of native cartilage by multizonal hybrid scaffolds from hydrogels and collagen and fibrinogen nanofibers. Moreover, we propose that chondrogenesis is potentiated by temporally controlled release of cartilage differentiation-inducing factors TGF-β3, kartogenin (KGN) and the novel factors LJ000328 and BNTA, with different mechanisms of action, either alone or in com¬bination. Human MSCs serve as cellular models to test our hypothesis. Our long-term vision is to use multizonal protein fiber scaffolds for release of such factors for cartilage regeneration in vivo. As a first step towards this vision, we aim to develop a scaffold-factor combination, which successfully allows in vitro-differentiation of MSCs into chondrocyte-like cells, ideally without hypertrophic features and mineralization. We pursue 4 aims within 4 work packages: Aim 1: Self-assembled, nanofibrous fibrinogen-collagen composites with multizonal architecture, adequate morphology, porosity, fiber orientation, swelling and mechanical properties are developed in WP 1 to serve as bio-inspired in vitro cartilage model. Aim 2: Establishment of a modular and tunable hydrogel platform for binding of TGF-3, KGN, LJ000328, and BNTA with tailorable release kinetics. Dextran, hyaluronic acid and alginate are used in WP 2 to modify the fibers to more closely mimic cartilage and to establish drug release systems through suitable linker systems and disulfide rebridging. Aim 3: Characterization of nanofibrous fibrinogen-collagen composites with hydrogels for tailored delivery of payloads. Here, the secondary structure of the scaffolds, reproducible release kinetics and maintenance of biological activity of the factors are evaluated (WP 3). This aim serves to select most promising scaffold-factor combinations. Aim 4: Assessment of cytocompatibility and in vitro-chondrogenic differentiation of MSCs mediated by the biologically active factors, alone and in combination, either by direct addition into the medium as solution or via release from with optimized, factor-loaded scaffolds. Overall, with this work program we will establish a new class of bio-inspired, layered protein fiber scaffolds for cartilage regeneration.

• DFG Programme: Research Grants