Scientists report tissue engineering success

06/15/05

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US scientists have successfully engineered blood vessels from human vascular cells in the lab, detailing their results in a research letter in this week's issue of THE LANCET.

Tissue engineering has made considerable progress in the past decade, but advances have stopped short of clinical application for most tissues. For elderly patients tissue-engineered arteries could provide grafts for bypass surgery. However, generating robust vessels using cells from elderly donors with vascular disease is difficult. One obstacle to generating tissue is the limited lifespan of adult human cells. Human cells have inbuilt timers called telomeres, which cap the ends of chromosomes, and get shorter every time a cell divides until there is nothing left and the cell stops dividing. Cells isolated from elderly people have shorter telomeres and therefore multiply less than cells from younger people. This is a problem for tissue generation because large numbers of cells must be cultured to produce vessels of clinically relevant size.

Laura Niklason (Duke University, NC, USA) and colleagues tested whether extending the lifespan of blood vessel cells could help generate blood vessels for elderly patients. The researchers took a sample of discarded vein from five elderly men after they had completed coronary bypass surgery. They isolated blood vessel cells from the tissues of each of the patients. They then infected some of the cells from each patient with a virus carrying an enzyme called human telomerase reverse-transcriptase (hTERT) that encourages the growth of telomeres. The investigators found that cells that did not have hTERT doubled their populations up to 34 times. However, cells that expressed hTERT carried on multiplying well beyond this point. The addition of the enzyme enabled vastly superior tissue development and the successful culture of engineered blood vessels for all of the patients studied.

Dr Niklason states: "Alternative sources of conduit are always needed in coronary and peripheral vascular surgery. Here, we have engineered blood vessels from vascular cells in elderly men. Our work represents a crucial initial step towards growing blood vessels that could be used to treat patients with vascular disease."

In an accompanying comment Howard Greisler (Loyola University Medical Center, Illinois, USA) concludes: "Poh and colleagues' report is an important advance in tissue engineering, in which a design is based on specific characteristics of the potential population of patients. The researchers provide a degree of optimism for the feasibility of clinical application of engineered blood vessels."

Source: Eurekalert & others

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