Development of Titanium/HA Scaffolds with Surface Immobilized BMP for the Creation of Functional Bone Tissue

Current treatments for major bone damage including war trauma resulting from gunshot or IED, often involve bone reconstruction through the use of a scaffold upon which osteoprogenitor cells can attach and start regenerating functional tissue. Traditionally, these scaffolds are made of titanium alloys and are coated with a hydroxyapatite (titanium/HA scaffolds). While moderately effective for small volume reconstruction, we propose that these implants can be made effective for large (<3cm) segmental trauma by immobilizing growth factors, bone morphogenetic proteins (BMP), onto the surface of the HA coating. We hypothesize that the BMPs would increase the rate at which the osteoprogenitors differentiate and rebuild the damaged bone matrix, leading to an overall decrease in healing time for the patient. In order to evaluate the effectiveness of embedded BMP on bone cell differentiation and overall bone matrix formation in titanium/HA scaffolds, experiments will be performed in vitro using human progenitor cells. Effectiveness of the immobilized coating will be performed using enzyme linked immune assays for cell expression of bone differentiation markers and by cell adhesion strength to the coating measured by cell integrin characterization and micromechanical force measurement.  Long term differentiation (bone matrix formation) will be studied through histomorphometric evaluation of the bone mineralization front. Quantification of the mineralization thickness (bone density) from the implant interface will be performed using immunofluorescence; the calcified migration front (bone length) will be quantified using BIOQUANT analysis software and reported as a percent contraction or expansion across the abutment/bone integration region.

Partially supported by UTSA WSRTP