Transforming growth factor-β1 accelerates bone bonding to a blended calcium phosphate ceramic coating: A dose-response study

In vivo strain measurements can facilitate the study of the bone remodeling response to loading and load changes. Calcium phosphate ceramic (CPC) coatings have been used to attach strain gauges to bone for extended periods of time, but require up to 12 weeks for adequate CPC-to-bone bonding. Transforming growth factor beta 1 (TGF-β1), an osteoinductive growth factor, was used as a surface enhancement to accelerate bone growth and bonding to CPC particles. The aim of this study was to find an optimal dosage of TGF-β1 to accelerate the attachment process. CPC-coated strain gauges were enhanced with doses of 0.5, 1.0, or 2.0 μg of TGF-β1 per gauge. Gauges were placed on the femora of dogs, which were exercised daily and fed ad libitum. After 3, 6, and 12 weeks, gauge attachment was quantitatively assessed using mechanical testing and histomorphometry. Gauge attachment was also qualitatively assessed using back scatter electron microscopy. Agreement of the mechanical test results with both the back scatter electron microscopy images and histomorphometry results showed that the 1.0 μg per gauge dose of TGF-β1 is an optimal dose to accelerate bone formation and attachment to CPC-coated strain gauges.