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[Effect of PTH and periodic tension on osteoblast-like cells for collagenase synthesis].

The purpose of the present study was to determine whether cyclically applied tension stimulates osteoblast-like cells to produce collagenase as well as parathyroid hormone (PTH) does. Experimental evidences suggest that osteoblast growth can be altered by various extrinsic control factors, including continuous and intermittent mechanical forces. In the present study, morphological change and collagenase synthesis were observed for both cultures that were added PTH and under the periodic tension condition applied on osteoblast-like cells and their parallel controls. periodic tension was used because it was thought to more closely mimic the in vivo functional situation. An initial seeding density of 50,000 cells/well was used for both the PTH stimulated and mechanically stimulated cells and their controls. For the mechanically stimulated cultures, the cells were subjected to the following tension/relaxation combination; 3 cycles/minute at 17% elongation of tensional force. The cells were fixed at 24, 72, and 120 hours after the start of experiments and collagenase was stained immunohistochemically. The following results were obtained: 1. PTH stimulated collagenase production from the first through the fifth day; 2. Periodic tension changed cell morphology from round to stellate; and 3. Periodic tension increased collagenase production from the first through the fifth day.