EASY HANDLING AND INJECTABLE CEMENT FOAM FOR BONE TISSUE ENGINEERING

International audienceCalcium phosphate cements (CPC) are widely used as bone substitutes because of their similar composition with the mineral phase of bone and of their injectability, making them of particular interest in mini‐invasive surgery. However, their bone healing properties are not sufficient to promote osteogenesis due to a poor macro‐porosity or an inadequate resorbability preventing cell migration and vascularization. In order to combine interconnected macro‐porosity and injectability, we perfected a promising approach, using a dual syringe mixing technique1, to produce foams composed of CPC and polymer with foaming agent. Among a dozen of formulations containing calcium deficient hydroxyapatite cement (CDHA) associated with different hydrogels were tested (e.g., alginate, chitosan, hyaluronic acid, gelatin). We selected two of them based on their biocompatibility and ability to form a hydrogel foam: 1) a silanized hyaluronic acid hydrogel creating the three‐dimensional network and Albumin as foaming agent (Si‐Hya Ac + RSA);2. a foaming gelatin‐based hydrogel (Gel). Their macro‐porosity between 100 and 300 μm and their young's modulus of 0.5 GPa for CDHA/Si‐Hya Ac + RSA and 1.8 GPa for CDHA/Gel respectively were closed to the porous ceramics2. Moreover, CDHA/Si‐Hya Ac + RSA and CDHA/Gel on STRO1 cells allowed to maintain their viability over 3 days. In vivo, critical size defects (6x10mm, n = 6/condition) were performed in femoral metaphysis of New‐Zealand white rabbits. Defects filled with the two new biomaterials exhibited greater mineral formation compared to the control, one week after the surgery suggesting a bone regeneration potential of our new biomaterials