Acceleration of bone healing by a growth factor-releasing allo-hybrid graft

Human amniotic membrane (hAM) has a highly biocompatible natural scaffold that is abundant in several extracellular matrix (ECM) components, including but not limited to platelet-derived growth factor (PDGF), transforming growth factor (TGF), and fibroblast growth factor (FGF). In our study, we have focused on a mixture of hAM and demineralized bone matrix (DBM) as an allo-hybrid graft to deliver it into the site of bone defect to decrease bone remodeling time.

Allo-hybrid grafts were prepared by coating the jelly made of decellularized and lyophilized hAM (AMJ) on the surface of DBM and subsequently underwent in vitro studies, such as alkaline phosphatase activity, MTT assay, and SEM analysis. Twenty-four male rats were included in the study, and after creating calvarial defects, rats were divided into four groups: DBM implanted, allo-hybrid implanted, AMJ injection, and a negative control (NC). Bone regeneration was assessed using computed tomography (CT scan) and histological analysis at 1, 2, and 3 months after surgery.

CT scan analysis clearly showed improved new bone growth in the allo-hybrid group compared to the NC group. Also, the Hounsfield unit of the allo-hybrid group (774.91 ± 47.8) after 90 days confirms CT scans. Histological staining revealed immature bone in allo-hybrid and DBM groups, along with the creation of a medullary cavity and bone marrow two months after surgery. Three months after surgery, the allo-hybrid group showed signs of new, mature bone, while no sign of healing could be seen in the NC group at any time points. Over a 90-day period, the allo-hybrid group recovered the bone defect area near 90 %. It is relatively twice as much as AMJ group.

Histological properties of bone defects and bone regeneration can both be improved by allo-hybrid grafts coated with AMJ.