U. of Colorado professor pioneering tissue engineering from knees to hearts to brains
University of Colorado at Boulder Professor Kristi Anseth, an investigator with the prestigious Howard Hughes Medical Institute, has high hopes for the future of tissue engineering as a way to make people healthier, happier and to live longer.
Anseth, a chemical and biological engineering professor, is considered by many to be the pioneer in this fledging field. She and her team – which includes 15 CU students -- were the first group to successfully develop an injectable and biodegradable "scaffold" to regenerate cartilaginous tissue using light-activated chemistries. "I believe that it will be routine in five to 10 years to see this procedure successfully working in human knees," she said.
The process involves using ultraviolet light to make repeating chains of complex molecules called polymers into degradable, three-dimensional scaffolds that can be injected with chondrocite cells that grow and multiply in the gel-like substance. The scaffolds, which can be injected into the knee as a fluid, dissolve after tissue regeneration, degrading over time as cartilage re-grows in knees.
"We and other tissue engineers now use this method to stimulate the growth of cartilage, skin, blood vessels and bone," said Anseth, the first engineer ever named a Hughes Investigator. "There are more complex challenges out there in this field, so we have had to become more clever and sophisticated in our designs."
Anseth presented her findings at the annual American Association for the Advancement of Science meeting held in Seattle Feb. 12 to Feb. 16.
She also is collaborating with faculty, researchers and students in the molecular, cellular and developmental biology department to bioengineer human heart valves.
Currently, faulty heart valves are replaced with mechanical valves that require the patients to take anticoagulants on a regular basis. While some heart valves are replaced with the heart valves of pigs, they eventually deteriorate and have to be replaced.
Anseth and a team led by Chair Leslie Leinwand of molecular, cellular and developmental biology now are designing gel for various heart valve cells. "This is more complicated because it requires the polymer scaffold to give instructions to the cells and provide an environment where the cells can communicate with each other," Anseth said.
Another complication is where to get the cells, she said. One emerging direction has been to take human stem cells from bone marrow. Stem cells are unique in that they can differentiate into other cells. As they grow on the uniquely designed gel scaffolds, the researchers have been able to get them to evolve into particular cell types, such as cartilage or bone-forming cells. "We have high hopes for this process," said Anseth.
In addition, Anseth is involved in clinical trials going on now at CU's Health Sciences Center in Denver that involve injecting stem cells into human brains in an attempt to treat Parkinson's disease and other brain diseases.
"This is a very tricky procedure," said Anseth, also a professor of surgery at CU-HSC. "Only about 5 percent of the injected stem cells survive, but we think we know how to get them to better survive and form functioning neurons by using our scaffold techniques and locally delivering signaling molecules to mitigate Parkinson's disease."
The most challenging problem facing Anseth and the tissue-engineering field is to regenerate organs such as hearts, livers or kidneys. There are more than 40,000 people in need of heart transplants in the United States annually, but only 2,000 to 3,000 donor hearts are available annually for such transplants.
"To achieve the engineering of complex organs, we need advanced scaffolds and templates that guide cell organization, control cell-matrix interactions, and provide structures and mechanics, as well as the necessary chemical signals in three dimensions," she said. Her group also has developed techniques to insert drugs, including growth factors, which are released into the body as the scaffolds disintegrate.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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