Cadmium is a toxic heavy metal that leaches into the environment, most notably through the improper disposal of electronics. Cadmium accumulates in bone and studies have linked low-level, chronic exposure to cadmium with the development of osteoporosis and other bone diseases. Our lab works to elucidate the direct effects of cadmium in bone-forming osteoblasts. Osteoblasts secrete an extracellular matrix (ECM) comprised of a calcium-phosphate crystalline component and a collagenous protein component. Other labs have shown that cadmium can displace calcium in calcium-phosphate crystals. We hypothesize cadmium exposure alters the nature of the ECM produced Saos-2 cells. After inducing cells to mineralize in the presence of cadmium we assessed cadmium incorporation in the ECM and subsequent changes in calcium, phosphate, and collagen deposition. Using surface plasmon resonance and column chromatography we explored cadmium-collagen binding interactions. We found cadmium binds collagen with different affinity than calcium. We are currently studying whether cadmium alters collagen fibrillogenesis, the spontaneous formation of the fibrillar structure found in bone. Collectively, these data suggest that cadmium disrupts the various components of the ECM secreted by osteoblasts.

Cadmium disrupts the extracellular matrix secreted by human osteosarcoma Saos-2 cells