Effects of Mechanical Stimulation on the Mechanical Properties and Calcification Process of Immature Chick Bone Tissue in Culture

Abstract

In order to study the adaptation mechanism of bone tissues, we cultured immature bone slices obtained from chick tibia under mechanical stimulation. We first cultured 2 to 3-mm-thick slices for 3 days while giving them cyclic compression up to 0.3N at the rate of 3–4 cycle/min. Both the stiffness and the calcified area of the bone tissues increased significantly under cyclic compression. Such increases did not occur in their static control, nor specimens deactivated with liquid nitrogen. We then cultured 0.2mm-thick slices for 24 hours while being stretched by 10%. Calcified area was significantly larger in stretched specimens than in the non-stretched control. Traveling direction of the calcification was roughly equal to the stretch direction. Collagen fibers showed alignment in the stretch direction over 5% of stretch. These results indicate that dynamic and quasi-static stretch stimulate calcification especially in the direction of stretch, and the calcification may occur preferentially along the direction of collagen fibers. The alignment of collagen fibers in the stretch direction and facilitated calcification along collagen fibers may have something to do with the alignment of trabecular bone in the direction of principal stress.