This video segment from Design Squad features the work of Howard Pryor, a tissue engineer and doctor at Massachusetts General Hospital. Dr. Pryor demonstrates a device he is working on to replace diseased livers. He explains the challenges of artificially engineering a human organ, including getting blood to flow through a device for processing just as it would through a liver. He also details the design process that helps all engineers not only analyze a problem and develop a solution, but also to test that solution and revise it as needed.
The loss or failure of human tissue and organs is one of the most frequent and costly problems in health care. Current treatments most often focus on surgical reconstruction and transplantation, or replacing damaged tissue or a diseased organ with a healthy specimen from another body. Tissue engineering is a multidisciplinary field that applies the principles of engineering and life sciences toward developing biological substitutes that are designed to restore, maintain, or improve tissue and organ function. While many tissue engineering products are naturally derived and designed to be absorbed by the body, some are made of synthetic materials, such as the artificial liver featured in the video segment.
Tissue engineering offers hope for hundreds of thousands of patients annually, largely because conventional transplantation has some major drawbacks. First, there is often a shortage of donor tissue and organs. Second, the survival rates for major organ transplantations are poor despite their high costs. And third, the body's immune system often rejects donated tissue and organs.
Biotech research into treating most tissue and organ failure has largely been focused on cell-based therapy, or the insertion of living cells or cell extracts into tissues to treat the cause of failure. These cells may come from a variety of sources, including the same person into which they will be implanted, the body of a donor of the same species, or individuals of another species.
The human liver aids in digestion and removes waste products and worn-out cells from the blood. About 30,000 people in the U.S. die each year from liver disease, making it the tenth-leading cause of death. At present, there is no therapeutic drug or device capable of performing the many functions of the liver, and the demand for liver transplantation is much greater than the supply. Stem cells, directed to differentiate into specific cell types, represent a potentially renewable source of replacement cells to treat many chronic and degenerative diseases. Devices such as the one featured in this video segment offer a different kind of solution.
Scientists have been successful at getting artificially engineered tissue and organs to grow and function in a lab. The real challenge is getting them to function long term in a human body. This means developing an implant that can be either absorbed by the body as the body regains the lost function, or one that can function indefinitely without being rejected or causing infection. Sometimes the design of a device or structure has to be reconsidered after testing, and adjusted several times before an acceptable solution is found.
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