Mesenchymal stem cells-seeded bio-ceramic construct for bone regeneration in large critical-size bone defect in rabbit

Bone marrow derived mesenchymal stem cells (BMSC) represent an attractive cell population for tissue engineering purpose. The objective of this study was to determine whether the addition of recombinant human bone morphogenetic protein (rliBMP-2) and insulin-like growth factor (IGF-1) to a silica-coated calcium hydroxyapatite (HASi)- rabbit bone marrow derived mesenchymal stem cell (rBlVISC) construct promoted bone healing in a large segmental bone defect beyond standard critical-size radial defects (15mm) in rabbits. An extensively large 30111111 long radial ostectomy was performed unilaterally in thirty rabbits divided equally in five groups. Defects were filled with a HASi scaffold only (group B), HASi scaffold seeded with rl3VISC (group C); HASi scaffold seeded with 113NISC along with rhl3MP-2 and IGF-1 in groups D and E respectively. The same number of rBMSC (five million cells) and concentration of growth factors rhBMP-2 (50ps) and IGF-1 (50g) was again injected at the site of bone defect after 15 days of surgery in their respective groups. An empty defect served as the control group (group A). Radiographically, bone healing was evaluated at 7, 15, 30, 45, 60 and 90 days post implantation. Histological qualitative analysis with microCT (pt-CT), haematoxylin and eosin (H & E) and Masson's trichrome staining were performed 90 days after implantation. All rhBMP-2-ackled constructs induced the formation of well-differentiated mineralized woven bone surrounding the HASi scaffolds and bridging bone/implant interfaces as early as eight weeks after surgery. Bone regeneration appeared to develop earlier with the rliBIAP-2 constructs than with the IGF-1 added construct. Constructs without any rItEMP-2 or IGF-1 showed osteoconductive properties limited to the bone junctions without bone ingrowths within the implantation site. In conclusion, the addition of rhBIVIP-2 to a HASi scaffold could promote bone generation large critical-size-defect.