Regenerative potential of nanoenabled collagen-polylactide scaffolds for osteochondral defect repair in rabbits

Lena Schröter¹Graciosa Quelhas Teixeira²Luisa de Roy²Benjamin Thilo Krüger²Oliver Küppers²Catarina Leite Pereira³Daniela Pereira Vasconcelos³Meriem Lamghari³Bruno Sarmento³Geir Klinkenberg⁴Ruth Schmid⁴Raquel Gracia⁵Janire Alkorta⁵Damien Dupin⁵Anne-Marie Haaparanta⁶Virpi Muhonen⁶Andreas Martin Seitz^2*Anita Ignatius²

• ¹Ulm University Medical Center, Institute of Orthopaedic Research and Biomechanics, Ulm, Germany
• ²Institute of Orthopaedic Research and Biomechanics, Ulm University Medical Center, Ulm, Germany
• ³Instituto de Investigação e Inovação em Saúde (i3S), Instituto Nacional de Engenharia Biomédica (INEB), Universidade do Porto, Porto, Portugal
• ⁴SINTEF Industry, Department of Biotechnology and Nanomedicine, Trondheim, Norway
• ⁵CIDETEC, Basque Research and Technology Alliance (BRTA), Parque Científico y Tecnológico de Gipuzkoa, Donostia-San Sebastián, Spain
• ⁶Askel Healthcare Ltd, Tampere, Finland

Current tissue engineering strategies for treating traumatic or degenerative cartilage defects in osteoarthritis (OA) remain insufficient in promoting robust tissue regeneration while simultaneously addressing inflammation, matrix degradation, and post-surgical infections. In this study, we evaluated the in vivo biocompatibility and regenerative potential of a nanoenabled collagen-polylactide (Col-PLA) scaffold functionalized with tri-combinatorial nanoemulsions delivering ibuprofen (anti-inflammatory), batimastat (BB-94, anti-proteolytic), and mupirocin (anti-bacterial). Using a femoral osteochondral defect model in New Zealand White rabbits, regeneration was assessed at 4-and 12-weeks post-implantation by macroscopic scoring, biomechanical indentation mapping, and histological analysis. Synovial inflammation was further evaluated via histology, CD8 immunostaining, and quantification of key pro-inflammatory mediators including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), prostaglandin E2 (PGE2), and matrix metalloproteinase-13 (MMP-13). Both functionalized and non-functionalized Col-PLA scaffolds supported significant host cell infiltration and tissue regeneration, outperforming untreated controls and demonstrating effective subchondral bone repair. A transient inflammatory response was observed in the nanoenabled group at 4 weeks, without elevation of synovial pro-inflammatory cytokines or compromised tissue regeneration. Although cartilage repair was comparable between scaffold groups, the nanoenabled Col-PLA scaffold might have a potential benefit in more complex or comorbid clinical scenarios due to its immunomodulatory, anti-proteolytic, and anti-microbial functionalization. The findings of this study support further investigations of these modular scaffolds in OA and infection-prone environments, using disease-relevant and long-term models, to fully establish its therapeutic applicability in regenerative medicine.