Spider silk protein used to engineer heart tissues

Scientists have successfully used artificial spider silk proteins to grow functional heart tissues, an advance that may help reverse cardiac damage in people who suffered from a heart attack.

Despite significant advances in preventing and minimising damage to the heart, ever more people are suffering from cardiac insufficiency. The main cause of reduced cardiac functionality lies in the irreversible loss of cardiac muscle cells due to disease, especially ischaemic diseases such as cardiac infarction or heart attacks.

There is still no treatment to reverse damage of this nature. Research is ongoing to develop methods of repairing such damage to normalise cardiac function.

Researchers at Friedrich-Alexander-Universitat Erlangen- Nurnberg (FAU) and University of Bayreuth in Germany investigated whether an artificial silk protein developed in the laboratory may be suitable for engineering cardiac tissue.

Fibroin, the protein that gives the silk its structure and mechanical stability, could be the key to artificial cardiac tissue, according to the study published in the journal Advanced Functional Materials.

Felix Engel from the University Hospital Erlangen in Germany had examined the properties of silk from the Indian silkworm and demonstrated its particular suitability as scaffolding material for engineering cardiac tissue.

Until now producing the protein in sufficient quantities and at a consistent quality had been impossible. Thomas Scheibel from the University of Bayreuth successfully produced a recombinant silk protein from garden spiders in the required larger quantities and of a consistent quality with the help of E coli bacteria.

This led the two researchers to join forces and further investigate the silk proteins of garden spiders. Researchers investigated the suitability of the silk protein eADF4(k16) produced in the laboratory for the production of cardiac tissue. The research involved applying a thin layer of the silk protein to a glass slide. The technique is based on the fact that cells with a negatively charged surface adhere to films made of eADF4(k16) due to its positive charge.

In addition to cardiac cells, researchers attempted to apply other cells, such as connective tissue cells and blood vessel cells, to the film, and were successful each time. Their investigations focused, in particular, on cardiac cell functionality. They compared these cells to cells they had applied to a film of fibronectin, which is similar to the natural environment of cardiac cells. No functional differences between the two were observed.

The researchers were able to demonstrate, for instance, that factors responsible for hypertrophy - enlargement of cardiac cells for instance in athletes and pregnant women - also led to a growth in volume in the cardiac cells that had been cultured on a film of eADF4(k16). The work represents the first steps towards future methods for engineering functional cardiac tissue, researchers said.