Silk Hearts

Tying in with what we've learned in class, this article from Science Daily explains how silk from a Tasar Silkworm can be used as a scaffold for heart tissue. In other words, how they can use this silk to replace damaged heart cells that are unable to regenerate. They are hoping that this artificial tissue can restore total cardiac function in humans.

Penny-sized silk discs used for heart scaffolding.

These types of studies are so important because, throughout evolution, the heart has lost all regenerative abilities. So when people have heart attacks, all of the cardiac cells that die are lost and cannot be replaced by the heart itself. These studies are conducted to test different types of materials that can patch these dead cardiac muscles. One of their main issues is trying to reconstruct this three-dimensional structure.

Various other materials have failed to work because they were too brittle, rejected by the immune system, or did not allow the muscle cells to adhere with the fibers. Fortunately, researchers are starting to believe that this silk can be a viable material for this heart operation.

The silk has a protein structure that is able to adhere strongly to the heart muscle cells. The coarser material allows the cells to grow and form three-dimensional structures. The re-patched rat heart was able to beat as if it were healthy after being patched with the silk. This is certainly a promising sign for the future and is an indicator that silk can be very successful.

 As the figure to the right demonstrates, the structure of the silk in the Tasar silkworm is very similar to that of spider silk as discussed in a previous blog post, which is what lends it its adhesive properties.

The silk itself is composed of highly crystalline B-sheets crosslinked with less-ordered B-sheets. As discussed in class, the crystalline structure of the more ordered B-sheets allows the atoms to be more tightly connected in a pattern, whereas the less-ordered sheets have an amorphous structure. Furthermore, the pleated B-sheets exhibit hydrogen bonding. As we also learned in class, this is the strongest intermolecular force and results in the interlocking strands. It is because of these properties that the silk is so strong and so capable of adhering tightly to the human body.

Unfortunately, they have been unable to obtain the necessary amount of cardiac cells for the starting material in humans. All tests were conducted on rats and were generally successful. On humans, however, much work still needs to be done. Scientists are in the process of using stem cells in place of these cardiac cells, but trials are still in the early stages.

Tissue engineering is a very important field for improving the overall life of humans. In my opinion, the studies conducted to improve the heart are some of the more important due to the vital role that the heart plays, as well as the fact that heart issues are very common. Any way that scientists can help this problem would be very beneficial to all that suffer from heart conditions.