Engineering calcium deposits on polycaprolactone scaffolds for intravascular applications using primary human osteoblasts

Total atherosclerotic occlusions often include significant calcium deposits. Current animal models do not mimic the pathology of gradual occlusion of arteries and lack cell-mediated calcium. The primary goal of this project was to establish an animal model incorporating these features into chronic total occlusions, using biodegradable scaffolds. As the first step, this study sought to determine the optimal dosage of TGF-β1 on polycaprolactone (PCL) scaffolds cultured with primary human osteoblasts (HOBs) to effectively induce in vitro calcification. HOBs were cultured in TGF-β1 and dexamethsaone (Dex)-supplemented medium in well plates. Calcium in the cultures was visualized using alizarin red. The highest calcification was observed in groups with both TGF-β1 (0.02 ng/ml) and Dex (10^-10 M) in the medium. Next, HOBs were cultured on PCL scaffolds with different loadings of TGF-β1: 0 (control), 5, 10, 50 and 100 ng. These cultures were performed with or without Dex (10^-10 M) in the medium. DNA content, ALP activity and the amount and distribution of calcium were examined at 7, 14, 21 and 28 days. TGF-β1 appeared to have an inhibitory effect on scaffold calcification when grown in Dex-supplemented medium. When cultured without Dex, the lower amount of TGF-β1 loading (5 ng) showed the most calcification, high DNA synthesis and high ALP activity on scaffolds. This study demonstrates the potential of implanting a PCL-HOB construct in an animal artery to establish a model of atherosclerotic occlusion with calcification.