A new study to understand how shear stress affects adult stem cell attachment may provide new insights into stem cells grafts, scientists at Thomas Jefferson University in Philadelphia have revealed.
"The advantage of using these stem cells is that they are easy to obtain in abundance from patients in which they are intended for use; however, it has been difficult to attach the stem cells to the surface of natural vascular tissue grafts," said Dr. Paul Paul J. DiMuzio, the leader of the research team.
Reporting the team's work at the 62nd Annual Meeting of the Society for Vascular Surgery, Dr. Eric S. Hager said: "After we change (differentiate) the stem cells into those resembling the lining of blood vessels (endothelial cells), we seed them onto the grafts and slowly introduce shear stress to improve their attachment. The current study investigates exactly how shear stress alters the way the stem cells adhere to vascular surfaces."
While presenting their work, the researchers said that they had examined the presence and function of molecules important for cell attachment (called integrins) on the surface of the stem cells.
Dr. Hager revealed that he began work on the research project with the hypothesis that "shear stress improves stem cell attachment to vascular basement membrane components via upregulation of integrin expression, similar to endothelial cells."
Dr. DiMuzio said: "Firm attachment of the stem cells to the vascular graft would allow for the formation of a confluent monolayer of cells in the hopes of improving graft function."
During the course of study, the research team exposed human adipose-derive stem cells (ASC) differentiated towards endothelial-like cells to physiological levels of shear stress.
They later measured the expression of integrins along with cell attachment to culture plates pre-coated with various vascular basement membrane components (collagen I, fibronectin, gelatin).
The researchers found that the human ASC expressed integrins, but at reduced levels compared to endothelial controls.
Dr. Hager said: "These data suggest that shear stress may be useful to improve the retention of stem cells to tissue engineered vascular grafts. Future experiments will evaluate how well the stem cell grafts function as a bypass for occluded arteries."