Thrombospondin promotes resorption by osteoclasts in vitro.
Dentine slices were soaked in TSP-1, FN or buffer before carrying out resorption assays using bone cell suspensions prepared from the long bones of 18-20-day old pre-hatch chick embryos. Soaking dentine slices in FN resulted in a five-fold increase in resorption over controls, while TSP-1 gave a two-fold increase. However, whereas the increase in resorption on FN-soaked slices could be explained by a vast increase in cell adhesion to the slices, TSP-1-soaked wafers showed no increase in cell adhesion. TSP-1, therefore, appeared to promote resorption by a mechanism other than simply increasing adhesion of stromal cells to the dentine slices. In confirmation of this, TSP-1 was able to further increase resorption on FN-soaked slices where cell adhesion was already maximal. We conclude that the effect of TSP-1 is on resorption, and that osteoclast resorption can be regulated by the presence of TSP in the matrix.
Carron
J A
JA
Department of Human Anatomy and Cell Biology, University of Liverpool, UK.
Walsh
C A
CA
Fraser
W D
WD
Gallagher
J A
JA
D000818:Animals; D001862:Bone Resorption; D002448:Cell Adhesion / Q000187:drug effects; D002642:Chick Embryo; D005353:Fibronectins / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000502:physiology*; D010010:Osteoclasts / Q000378:metabolism / Q000502:physiology*; D019699:Thrombospondins
D005353:Fibronectins; D008562:Membrane Glycoproteins; D019699:Thrombospondins