Description of Project:

Vascular calcification is the deposition of calcium phosphate mineral in cardiovascular tissues. It is a clinically significant complication associated with atherosclerosis, arteriosclerosis, diabetes, renal failure, and is a common consequence of aging. Vascular calcification is known to contribute to morbidity and mortality associated with both diabetes and renal failure, and is a major cause of failure for both native and tissue prosthetic heart valves, affecting 1%-2% of the aging population. Therefore, elucidation of the cellular mechanisms involved in vascular calcification is important as it will aid in the development of relevant therapeutics.

Ms. Curinga is studying the phenotypic changes of arterial smooth muscle cells in response to treatment with elevated levels of inorganic phosphate (Pi), 2.4mM. She has generated an in vitro bovine aortic smooth muscle cell (basmc) model by isolating a large population of arterial smooth muscle cells from bovine aorta. This system has been used to demonstrate that treatment with elevated Pi leads to extracellular mineral deposition and, interestingly, that mineral deposition is accompanied by a phenotypic change in which smooth muscle cell markers sm22a and a-smooth muscle actin are lost, and the osteoblast-determining transcription factor, Cbfa1, and bone associated proteins osteopontin, osteocalcin, and alkaline phosphatase are gained. To investigate the role of Cbfa1 in basmc mineralization directly, a dominant negative Cbfa1 retroviral construct was created and used to generate stable cell lines. Preliminary results indicate that cells stably expressing dominant negative Cbfa1 deposit significantly more mineral than control cells when treated with elevated Pi. Northern analysis and RT-PCR are currently underway to determine the expression profile of these stable lines in the presence of elevated Pi. To further elucidate the relationship between Cbfa1, mineralization, and basmc phenotypic changes, cell lines stably over expressing wild type Cbfa1 will be treated with elevated phosphate and analyzed for mineral deposition and gene expression.