Molecular Diffusion From Bone Into Cartilage: A Study of the Osteochondral Junction

Osteoarthritis is an idiopathic joint disease that affects 13% of Canadians. To gain a better understanding of the biochemical relationship between the bone and cartilage, molecular diffusion across the bone-cartilage junction was assessed. Passive diffusion of a small (605 Da), nutrient-sized, contrast agent across the osteonchondral junction was successfully measured using contrast-enhanced MRI. This method could be employed for future in vivo studies. The osteochondral junction was simulated using a finite difference method to assess the subchondral bone as a barrier. The average resistivity value was 1.65x10-6 s-1. Inclusion of resistivity in the simulation produced a better fit of the experimental data. The osteochondral junction’s permeability to larger, protein-sized, solutes was assessed by attempting to diffuse fluorescent tracers (3-70 kDa). The selected fluorescent tracers were unable to passively diffuse across the osteochondral junction. This thesis provided a better understanding of the crosstalk between bone and cartilage.