Scientists use silk from the tasar silkworm as a scaffold for heart tissue

Of all the body’s organs, the human heart is probably the one most primed for performance and efficiency. Decade after decade, it continues to pump blood around our bodies. However, this performance optimisation comes at a high price: over the course of evolution, almost all of the body’s own regeneration mechanisms in the heart have become deactivated. As a result, a heart attack is a very serious event for patients; dead cardiac cells are irretrievably lost. The consequence of this is a permanent deterioration in the heart’s pumping power and in the patient’s quality of life.

In their attempt to develop a treatment for the repair of cardiac tissue, scientists are pursuing the aim of growing replacement tissue in the laboratory, which could then be used to produce replacement patches for the repair of damaged cardiac muscle. The reconstruction of a three-dimensional structure poses a challenge here. Experiments have already been carried out with many different materials that could provide a scaffold substance for the loading of cardiac muscle cells.

“Whether natural or artificial in origin, all of the tested fibres had serious disadvantages,” says Felix Engel, Research Group Leader at the Max Planck Institute for Heart and Lung Research in Bad Nauheim. “They were either too brittle, were attacked by the immune system or did not enable the heart muscle cells to adhere correctly to the fibres.” However, the scientists have now found a possible solution in Kharagpur, India.

At the university there, coin-sized disks are being produced from the cocoon of the tasar silkworm (Antheraea mylitta). According to Chinmoy Patra, an Indian scientist who now works in Engel’s laboratory, the fibre produced by the tasar silkworm displays several advantages over the other substances tested. “The surface has protein structures that facilitate the adhesion of heart muscle cells. It’s also coarser than other silk fibres.” This is the reason why the muscle cells grow well on it and can form a three-dimensional tissue structure. “The communication between the cells was intact and they beat synchronously over a period of 20 days, just like real heart muscle,” says Engel.

Despite these promising results, clinical application of the fibre is not currently on the agenda. “Unlike in our study, which we carried out using rat cells, the problem of obtaining sufficient human cardiac cells as starting material has not yet been solved,” says Engel. It is thought that the patient’s own stem cells could be used as starting material to avoid triggering an immune reaction. However, exactly how the conversion of the stem cells into cardiac muscle cells works remains a mystery.

More information: Chinmoy Patra, Sarmistha Talukdar, Tatyana Novoyatleva, Siva R. Velagala, Christian Mühlfeld, Banani Kundu, Subhas C. Kundu, Felix B. Engel
Silk protein fibroin from Antheraea mylitta for cardiac tissue engineering, Biomaterials, Advance Online Publication Januar 10, 2012

Provided by Max-Planck-Gesellschaft (news : web)

New silkworm diet produces colored silk and possible medical advantages

The Institute of Materials Research and Engineering (IMRE) in Singapore has developed a way to replace the traditional dying process necessary to make colored silk. A simple dietary change for the silkworm larva and they are able to produce silk in a variety of colors, with the color directly integrated into the fibers.

The process designed by the researchers involves feeding a diet of mulberries treated with fluorescent dye to the silkworms in the last four days of the larva stage. Once the silkworms ingest the dye they then turn the color of the dye they were fed. The silkworms then spin their cocoon with the resulting color of the silk matching the dye they ingested.

By integrating the dye directly into the silk before it is even spun creates a more environmentally friendly process for adding color to silk. The current process of dying silk requires large amounts of water as well as chemicals, and is extremely time consuming. By refining this process to get the desired colors, the need to dye silks in the traditional way may be eliminated.

Researchers believe that this method can be adapted for large scale farms and is very cost effective. The addition of the dyes to the silkworm diet does not alter the structure of the silk itself, so once the cocoons are spun, they can be harvested and processed utilizing normal procedures.

The integration of dye into the silkworm’s diet to create a colored silk has also opened the door to other possibilities. With the strength of silk itself, it has been used for many years as sutures and wound dressings. Researchers are now looking into the possibility of adding different compounds to the silkworm diet to produce silk with antibacterial, anticoagulant, and anti-inflammatory properties.

This new research holds the benefit of not only reducing the environmental footprint by eliminating the dying process for silk, but could lead to possible breakthroughs in medical treatments and wound care.

More information: Intrinsically Colored and Luminescent Silk, by Natalia C. Tansil et al., Advanced Materials, Article first published online: 9 FEB 2011. DOI:10.1002/adma.201003860