Genetically engineered threads of a protein found in spider webs have provided a perfect foundation for growing heart tissue cells, raising hopes of someday repairing damaged hearts or even growing new ones, researchers say.

Growing tissues or organs from a patient's own cells outside of the body for later implantation is a new frontier in medical research, with the ultimate goal of solving the issue of transplant rejections, they say.

However, a serious challenge is finding a foundation, or substrate, on which to cultivate the new cells, a problem that scientists at the Moscow Institute of Physics and Technology say they have had some success in solving.

By genetically engineering a protein known as spidroin, found in the silk that spiders create in order to spin their webs, they have found what they have described [pdf] in the journal PLOS ONE as the perfect material that will allow tissue to grow but that will not be rejected by the human body when the resulting tissue or organ is transplanted.

Researchers have already used spidroin to grow cartilage and tendons as well as bone implants, so the Moscow scientists wanted to see if spidroin engineered in their lab could be utilized to cultivate cardiomyocytes, the cells that make up heart tissue.

They found it to be an ideal material; the fibers are five times as strong as steel and twice as elastic as nylon, capable of stretching another third of their length.

In their experiments, they seeded a matrix of spidroin fibers with neonatoal rat heart cells, monitored their growth, and tested their ability to contract and to conduct electrical impulses, both vital in heart cells.

Within three to five days, they report, a layer of cells had formed, which displayed the ability to contract in synchrony and pass electrical impulses in the same manner that the tissue of a living heart does.

"We can answer positively all questions we put at the beginning of this research project," said Konstantin Agladze, who heads the institute's Laboratory of the Biophysics of Excitable Systems. "Cardiac tissue cells successfully adhere to the substrate of recombinant spidroin; they grow forming layers and are fully functional, which means they can contract coordinately."

While the prospect of growing a replacement heart or other organ from a patient's own stem cells, which can then be transplanted without fear of rejection and eliminating the often dangerous wait for a suitable donor organ, is likely far in the future, current research like the Moscow work could be one step in that direction.

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