Up for Debate: Cells vs. Molecules for Repair of Cardiac Tissue 

Key Points:

In end-stage HF, function will not be restored if growth factors are simply injected into scar tissue.

By TCT Daily Staff

In a session held Monday about the future of cardiac cell therapy, four experts considered whether whole cells or small molecules and proteins represent the best strategy for restoring function to damaged cardiac tissue.

New tissue needed

Stefanie Dimmeler, PhD, from the University of Frankfurt, Germany, and Frank J. Giordano, MD, of Yale University School of Medicine, in New Haven, Conn., discussed the role of proteins and small molecules in cardiac tissue repair. Dimmeler focused on the example of scar tissue in assessing the therapeutic value of different factors for cell therapy.

"Scar tissue is dead, and you need to provide something living [to repair it]. We will not solve the problem of end-stage heart failure if we just inject growth factors into scar tissue," he said. "You need something to introduce new tissue, and for this, cells might be a good way."

Giordano, though, questioned whether "you can really make any kind of functional change in the heart based on myocyte differentiation."

For example, there are roughly 2.6 billion muscle cells and twice that number of other cell types in the heart. If 10 million cells are injected and if all of them survive, that would represent only a tiny change in the total number of cells, Giordano said.

"To think that is going to change heart function is a bit of a reach. What is more viable is [to create] a delivery system or a matrix to capture and inject what it is you want to deliver," he said.

More than the sum of its parts

Jonathan M. Hill, MB, ChB, of King’s College Hospital in London, argued in favor of the primacy of cells for cardiac tissue repair. "It’s a retrograde, reductionist step to say we can achieve this complex effect of the biology of the cell, which cannot be replicated by one pathway or one molecule," he said. "We have to think in terms of the biology of systems. Cells are here to stay, but whether they are cells to deliver small molecules and proteins, I don’t know."

Keith L. March, MD, PhD, of the Indiana Center for Vascular Biology and Medicine in Indianapolis, suggested there is little to debate. "Both views are reductionist. It is important to build upon what is happening now with cells, as in the REPAIR-MI trial," he said. "It is also probably true that one cell [type] is not enough. The fact is everything that’s been said here is compatible."

Disclosures:

Drs. Dimmeler, Giordano, Hill, and March report no relevant conflicts of interest.

 （source：www.tctmd.com）