Increase in the potential of osteoblasts to support bone resorption by osteoclasts in vitro in response to roughness-of bone surface

The development of the potential of osteoblasts to support bone resorption by osteoclasts in response to roughness on bone slices was examined in the co-incubation cell system of immature osteoclasts and osteoblastic cells. The immature osteoclasts, which need alkaline phospatase (ALP)-positive osteoblastic cells for bone resorption, were generated in mouse spleen cultures with I, 25-dihydroxy-vitamin D-3 and prostaglandin E-2. ALP-negative osteoblastic cells from mouse calvaria were incubated on rough surfaced bone slices for 3 days. The number of ALP-posirtve cells increased greatly on the rough surface, but little on the smooth surface. When immature osteoclasts were added and incubated for 1 more day, the resorption pit number and the total pit areas on the smooth surface were not much different from those before incubation but were approximately four times higher on the rough surface.