March 22, 2001
New materials hold promise for human
WEST LAFAYETTE, Ind. Purdue University researchers have discovered new materials that offer promise in repairing and replacing damaged human tissues in parts of the body ranging from intestines to vocal cords.
The materials are derived from the stomach, urinary bladder and liver of pigs and other animals, said Stephen Badylak, a senior research scientist in Purdue's Department of Biomedical Engineering. They are sterilized, processed into sheets, tubes and other shapes and grafted into areas that need to be replaced or repaired.
"It's not just an inert structural component," Badylak said. "It actually functions as a communication highway between cells."
In animal tests, the materials have been shown to work as a scaffolding that communicates with surrounding cells and facilitates the repair of damaged tissues. The scaffolding eventually disappears as it is assimilated into the surrounding tissues. Moreover, the materials are not rejected by the host animals, and it is unlikely that rejection will be a problem in human treatment, Badylak said.
The university is seeking companies to license the new materials in order to develop them into products that can be used in medical treatments for humans.
"Tissue engineering will play a very important role in the health care of the nation, and Purdue has an excellent reputation for its biomedical engineering program and specifically this kind of research," said Lisa Kuuttila (COO-tih-luh), assistant vice president and director of the Office of Technology Commercialization at the Purdue Research Foundation. "We seek to license our technology to selected companies that have an interest in developing it and are willing to commit to arrangements that promise the greatest public benefit."
Purdue has issued a request for proposals, setting deadlines of April 30 for companies to submit an initial response expressing interest and June 30 for submitting complete proposals.
A team led by Badylak had previously pioneered research that resulted in medical applications for a material taken from the small intestines of pigs. That material, called small intestinal submucosa (SIS), is now being used to treat urinary incontinence in women, repair internal organs and damaged ligaments, and cure skin wounds and chronic sores. Two Indiana companies hold licenses from Purdue to develop SIS for some applications. More than 20,000 people have been treated with SIS.
Like SIS, the new materials are part of a family of scaffolding materials referred to as the extracellular matrix.
"These materials differ from SIS in that they have distinctive structures, contain different quantities and types of proteins, and have different mechanical and physical properties, all of which may make them particularly suited for specific applications," Badylak said.
Two of the new materials are derived from a layer of tissue, known as the submucosa, in the stomach and urinary bladder. This tissue layer contains numerous proteins, including collagen, a fibrous material that gives body parts strength and flexibility.
Research indicates that the urinary bladder material shows promise in possibly repairing the human esophagus and replacing vocal cords and structures in the larynx removed in cancer surgery or damaged in trauma. The only option for such patients currently is to use artificial devices that enable them to speak.
The third material is derived from the livers of pigs and other mammals.
"We remove the cells that are part of the liver and are left with only the matrix, something that looks a lot like a honeycomb," Badylak said. "This matrix supports an extremely dynamic population of liver cells, which have terrific regenerative capacities."
Researchers hope that, like SIS, the new materials will prompt the body to replace damaged tissues with little or no scarring, recreating the healing efficiency of young children. Purdue scientists discovered SIS' healing qualities unexpectedly about 15 years ago while looking for ways to make substitute blood vessels.
"In the early 1990s, we started asking, 'If an extracellular matrix from the small intestine causes this healing response, isn't it possible that extracellular matrices from other tissues might also have exciting potential?'" Badylak said.
The materials function as a natural framework for repairing and growing tissue, and they contain "growth factors" and other proteins that signal the healing process.
Proteins in the materials relay information and instructions to each other and to surrounding cells. The resulting new tissue growth is essentially the same shape and performs the same functions as the damaged tissues.
The research is funded by Purdue and the National Institutes of Health.
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