ATOMIC FORCE MICROSCOPE PROBES LIVING HEART CELLS

November 13, 1996
Media Contact: John Cramer
Phone: (410) 955-1534
E-mail: jcramer@welchlink.welch.jhu.edu

Heart cells' "skeletons" may help control their internal chemical activities, according to a Johns Hopkins study using a microscope that forms images by sliding a tiny needle over the surface of living cells.

The findings suggest that measuring elasticity of some heart cells may improve understanding of healthy and diseased cells, leading to better diagnosis and treatment of heart disease, according to scientists. The results also provide the first evidence that disrupting a particular protein weakens the cellular "skeletons" -- the protein fiber network supporting the cell membrane -- of some heart cells.

The results will be presented 10 a.m., Nov. 12 at the American Heart Association's 69th annual Scientific Sessions in New Orleans.

"Our results suggest atomic force microscopy is a powerful tool for better measuring and understanding what's going on inside these cells," says Frank Chi-Pong Yin, M.D., Ph.D., the study's senior author and a professor of medicine.

Yin's team reduced the normal amount of the protein actin in the "skeletons" -- which act like tent poles holding up a tent -- of living connective tissue cells in the heart. The scientists then used an atomic force microscope, which also measures a cell's mechanical properties, to touch the outer surface of the cells.

Cell surfaces usually have hard and soft regions, but the results show that cells with less actin lost elasticity over their entire surface -- like a tent with the poles removed. This suggests that actin plays an important role in a cell's structural integrity and internal chemical activities.

The scientists were testing whether actin helps control the cells' internal motions, and whether reducing actin would affect the cells' structure and function. Cells, whether normal or abnormal, are always active. This includes occasionally disassembling and reassembling their skeletal fibers -- like the folding and unfolding of tent poles -- as the cells carry on chemical reactions.

The scientists' next step is determining if a less elastic "skeleton" prevents cells from functioning normally. This may eventually help to develop therapies to repair abnormal cells or stop them from doing harm, says Yin.

The study's others authors are Karen May-Newman, M.D., Pascal Goldschmidt, M.D. and Jan Hoh, Ph.D.



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