Heart Cells on the Beat

Each year 1.1 million Americans suffer heart attacks, almost half of which prove to be fatal.  During a heart attack, blockage of the coronary artery temporarily cuts off blood supply to the cardiac tissue.  The lack of oxygen kills heart cells, resulting in irreversible damage.  Traditionally there is little to no hope of regaining function in damaged heart tissue, but help may be on the way.  Scientists at the University of Arizona have found that cardiac cells from rats, when adhered to a biodegradable mesh, will beat in rhythm.  The research, hailed by the American Heart Association as one of the most noteworthy achievements of the year, could possibly lead to the development of a living bandage for treating damage from heart attacks. 

Dr. Steven Goldman and Jordan Lancaster applied several million heart cells, called cardiomyocytes, to an artificial patch and found that within 72 hours the cells began beating.  Surprising the scientists, the individual contractions of the cells spontaneously coordinated, causing the entire scaffolding to pulse in a remarkable parallel to in vivo heart tissue. 

Without input from the scientists, the rat heart cells settled into a rhythm of 70 beats per minute, slower than the 330-480 beats per minute typical of most rats.  The researchers found that the cells sped up their pace if subjected to electric shock, approaching up to 300 beats per minute if stimulated.  Most encouraging to the team was that as the cells increased their rate, they stayed in time with each other.

Heart cells beating outside the body isn’t an unusual concept.  Cardiomyocytes feature contractile proteins that help the cells pulse.  While it wasn’t unexpected that the cells would beat, it was assumed that they would pulse sporadically and independently of their neighbors.  Dr. Goldman was surprised with what happened.  “The fact that they beat synchronously and the whole thing contracts means that the cardiomyocytes are talking to each other.”

The patch they used as a framework is a biodegradable mesh formed from fibroblasts, a type of connective tissue involved in wound healing.  It was designed by Theregen, a regenerative medicine company, to help mend heart tissue.  The patch itself is currently in the clinical trial stage of the FDA approval process, but the application of living heart cells is a novel approach and will require significant testing before it would be available to patients.

The goal is to develop a living band-aid created from the mesh and heart cells, which could be attached directly to damaged cardiac tissue.  As demonstrated by this study, it seems likely that the newly applied cells could communicate with the existing heart tissue and match the pulse rate of the patient’s heart.  The researchers are hopeful that as the patch disintegrates, the healthy cells will remain and help replace the damaged cells.  If successful, this work could forge powerful new techniques in medicine’s fight against heart disease.

For more information:

Video of the beating heart cells with excellent explanation of the research : http://www.sciencefriday.com/videos/watch/10230

Explanation of Heart Attacks from the National Institutes of Health : http://www.nhlbi.nih.gov/health/dci/Diseases/HeartAttack/HeartAttack_WhatIs.html