Endothelial Cells and Bone Cells

Abstract

There is a long, and distinguished tradition of belief in the theory that endothelial cells give rise to bone cells. Haller (1763), Hunter (1835) and Keith (1927) have all proposed that bone originated from the blood vessels. Figure 1 shows a schema of the progeny of bone cells proposed by Trueta (1963) who envisaged a syncytium of cells originating from the endothelial cell and terminating in the osteocyte. According to Trueta (1963), dying osteocytes and endothelial cells produce a vascular stimulating factor which attracts vessels to the fracture site. As a consequence, in the fracture callus, vessels migrate towards the ischaemic area at the centre of the fracture. Bone deposition radiates from, and is moulded onto, the vascular pattern. Trueta’s schema is based on the concept of contiguity of cells. Recently, Brighton and Hunt (1991) provided electron microscopic evidence in support of the theory. This evidence is only indirect, however. The fact that cells are lying next to one another is not a conclusive proof that they are related. On the other hand, Hulth et al. (1990) using immunocytochemical methods which localised laminin and other basement membrane components have demonstrated vessel-like structures in the callus cartilage. These findings have not yet been corroborated.