Developments in the field of additive manufacturing have allowed significant improvements in the design and production of scaffolds with biologically relevant features to treat bone defects. Unfortunately, the workflow to generate personalized scaffolds is source of inaccuracies leading to a poor fit between the implant and patients' bone defects. In addition, scaffolds are often brittle and fragile, uneasing their handling by surgeons, with significant risks of fracture during their insertion in the defect. Consequently, we developed organo-mineral cementitious scaffolds displaying evolutive mechanical properties which are currently being evaluated to treat maxillofacial bone deformities in veterinary clinics. Treatment of dog patients was approved by ethic and welfare committees (CERVO-2022-14-V). To date, 8 puppies with cleft palate/lip deformities received the following treatment. Two weeks prior surgery, CT-scan of patient's skull was performed to allow for surgical planning and scaffold designing. Organo-mineral printable pastes were formulated by mixing an inorganic cement precursor (α-Ca3(PO4)2) to a self-reticulating hydrogel (silanized hyaluronic acid) supplemented with a viscosifier (hydroxymethylpropylcellulose). Scaffolds were produced by robocasting of these pastes. Surgical interventions included the reconstruction of soft tissues, and the insertion of the scaffold soaked with autologous bone marrow. Bone formation was monitored 3 and 6 months after reconstruction, and a biopsy at 6 months was performed for more detailed analyses. Scaffolds displayed great handling properties and were inserted within bone defects without significant issue with a relevant bone edges/scaffold contact. Osteointegration of the scaffolds was observed after 3 months, and regeneration of the defect at 6 months seemed quite promising. Preliminary results have demonstrated a potential of the set-up strategy to treat cleft lip/palate deformities in real, spontaneous clinical setting. Translation of these innovative scaffolds to orthopedics is planned for a near future.

Introduction and Objective

Osteoarthritis (OA) is the most common inflammatory and degenerative joint disease. Mesenchymal Stromal Cells (MSCs), with their chondro-protective and immune-regulatory properties, have been considered as a new approach to treat OA. Considering the risk of cell leakage outside the articular space and the poor survival rate after intra-articular (IA) injection, we hypothesized that cell encapsulation in cytoprotective hydrogels could overcome these limitations and provide cells with a suitable 3D microenvironment supporting their biological activity. We previously generated micromolded alginate particles (diameter 150 μm) and demonstrated the long-term viability of microencapsulated MSCs isolated from human adipose tissue (hASCs). Encapsulated cells maintained their in vitro ability to sense and respond to a pro-inflammatory environment (IFN-γ/TNF-α or synovial fluids from OA patients) by secreting PGE₂, IDO, HGF and TGF-β. In this study, we evaluated the anti-OA efficacy of these microencapsulated hASCs in a post-traumatic OA model in rabbits.