Narrow Results

Bone or cartilage cells are essentially colorless, and it is difficult to distinguish their morphologies under a light microscope. To better visualize these structures, various staining techniques have been developed; due to page constraints, we will only describe the most common methods for readers. These staining assays include hematoxylin and eosin (H&E) stain, used for general histology of the cell; Safranin O stain, used for the cartilage; and von Kossa and van Gieson stains as well as modified Goldner's trichrome stain, used for nondecalcified tissues.

Bone-forming cells first fabricate a highly organized oollagen matrix, osteoid, which subsequently mineralizes. A variety of cell culture systems exist for osteogenic cells, yet none of these is optimal for the well-organized formation of a mineralized matrix. We have generated collagen substrates which have different degrees of fibrillar orientation, and have cultured osteogenic cells on these matrices. Osteoblast-rich cells isolated from 16 day chick embryos were cultured in micro-mass culture on the collagen sheets. Von Kossa-stained sections showed that highly oriented collagen matrix started to calcify in 6-7 days while a random fibrillar matrix did not mineralize even in 21 days. Mineral has been detected only within the collagen matrix with a narrow unmineralized region between the cells and the mineral like osteoid in vivo. The in vitro system described may serve as implantable materials facilitating in situ cell-mediated bone repair ultimately.