Although people do regularly recover from heart attacks, the heart itself never entirely "gets better." This is because cardiac muscle tissue doesn't regenerate - any that dies in the event of a heart attack will only be replaced with inactive scar tissue, and the heart's performance will be permanently compromised as a result. Scientists have responded by trying to develop heart patches made of materials that act as nanoscale scaffolds, upon which new cardiomyocytes (heart cells) can grow. Materials used for these scaffolds have included fibrin, nanofiber, gold nanowires and polymer. Now, new research is suggesting that silkworm silk may be a better choice than any of those.
For some time now, scientists from Germany's Max Planck Institute for Heart and Lung Research have been among those researching ways of growing cardiac tissue on three-dimensional scaffolds. Everything that they looked at, however, had limitations.
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"Whether natural or artificial in origin, all of the tested fibers had serious disadvantages," said research group leader Felix Engel. "They were either too brittle, were attacked by the immune system or did not enable the heart muscle cells to adhere correctly to the fibers."
It turned out, however, that scientists from the Indian Institute of Technology, Kharagpur had been working on an alternative - coin-sized disks made from the cocoon of the tasar silkworm. Not only is the silk coarser than other silk fibers, making it better-suited for use as a scaffold, but its surface also contains proteins that facilitate the adhesion of cardiomyocytes. When the silk was tested at the Max Planck Institute, heart cells from rats that were seeded onto it were able to remain in communication with one another, and beat synchronously for 20 days.
Before the silk patches can ever see clinical use, however, the scientists need to figure out a safe way of procuring a sufficient amount of heart cells from the patient. Using stem cells is a possibility, although finding a way of getting those to convert into heart cells still poses a challenge.