A new way to repair damaged heart tissue

ALTHOUGH the possibility is several years away, people may one day be helped to recover from heart attacks by having specially engineered patches that have been seeded with cardiac cells placed over the damaged tissue in their hearts. The idea is that these cell-impregnated patches will encourage the regeneration of heart muscle. Laboratory studies using animals suggest the advantages could be so great that it is worth the risk of the surgery needed to put such patches in place; they might even provide an alternative to heart transplants. The problem is finding a suitable way to make the patches stay put.

Stitching is one possibility, but sutures bring risks. They might block the blood supply to the vulnerable area, or injure nearby healthy tissue, or cause haemorrhages. They might also introduce harmful bacteria. Nor is gluing—an obvious alternative to stitching—much better in practice. Some glues stiffen with age. Some are mildly toxic. Some are not porous enough to permit cells to grow and move around. To ameliorate these problems one of the researchers working on such patches, Tal Dvir of Tel Aviv University, in Israel, is developing a new type of cardiac scaffold that can secure a patch in place using light instead of stitches or glues.

Dr Dvir’s inspiration came from recent work his research group has carried out using tiny particles of gold. These can be warmed and manipulated by light from the red end of the spectrum, which travels well through tissue. He found himself wondering whether he could create a supportive scaffold by mixing albumin, a common protein, with tiny particles of gold and then sculpting the resultant material with a laser into a shape that would fit the damaged tissue so snugly that neither stitches nor glue would be needed.

To this end, as he and his colleagues explained recently in Nano Letters, they mixed albumin with a solution of beta-mercaptoethanol and trifluoroethanol, which softened the protein so that they could spin it into ribbonlike fibres. They used these fibres to build cardiac scaffolds, then soaked the scaffolds in suspensions of the golden particles for an hour, during which period most of the particles attached themselves to the scaffolds. After that, they added the cardiac cells.

This done, they tried attaching the scaffolds to hearts taken from pigs. They laid them on the organs and played the laser over them. As they had hoped, this softened the scaffolds, which then moulded themselves to the surrounding tissue and subsequently remained in place.

Dr Dvir worried, however, that heat generated when the laser struck the gold would end up cooking nearby tissue. To assess that risk he ran a second experiment. In this the team applied the scaffolds to the hearts of living rats, fused them into place with the laser and then studied those hearts for cell damage. They found none. More importantly, when they analysed the patched hearts in situ for health and function, they noted that the scaffolds were not impeding them at all.

There is a long way to go, but Dr Dvir does seem to have found a promising way that one day could help people recover from heart failure.