Monday, September 14, 2009

2009 Lasker Awards in Medical Research

John Gurdon and Shinya Yamanaka were honored yesterday as recipients of the 2009 Albert Lasker Award for Excellence in Medical Research. This prize has been considered the most prestigious in American medical science; fifty percent of winners have gone on to also win Nobel prizes. The research of these two sounds astoundingly futuristic-- they have essentially learned how to reprogram cells to revert them back to their embryonic state. In essence, these researchers take adult cells and revert them back to stem cells, which can be used in a variety of ways while leapfrogging some of the socially-imposed roadblocks to traditional stem call research. This new technology indicates that all cells retain their initial genes, despite maturing into different cellular functions. In theory, this creates the potential to re-develop a mature cell for use in "experimental or therapeutic purposes". In terms of therapy, these cells have the potential to uninvasively help replace damaged tissues without the risk of immune rejection of foreign tissues. Experimentally, these cells can be used to test new drug treatments accurately without the risk to human life that a human drug trial would entail.

This new technology seemed to contradict the doctrine of differentiation. Little understood by biologists, differentiation is the process by which a cell becomes set to a specific purpose, and loses its capacity to perform other cellular functions. Two theories prevail about the mechanism of this process. One is that cells shed genes that they no longer need as they age-- i.e. a muscle cell no longer needs to perform the functions of a blood cell. The other is that cells retain all of their genetic components, but are able to switch them on and off as necessary.

In the 1950s, Gurdon's original experiment overturned conventional scientific thought that once cells had differentiated, they were permanently set that way. Gurdon was able to regrow an adult frog's skin cell into an embryonic cell, and thereby grow a tadpole. Conclusions of this experiment "showed that a completely differentiated nucleus was indeed totipotent: It could direct the formation of all cells, including eggs and sperm, necessary to compose a completely functioning adult". Gurdon's work was the predecessor of Keith Campbell's research and eventual successful cloning of Dolly the sheep.

In the 1990s, Yamanaka took this research a step further in an attempt to circumvent controversy about the use of embryonic stem cells to grow adult tissue. Perhaps the opposite was true-- adult cells could be converted to embryonic ones. Searching the genome for a series of genes found in embryonic stem cells in mice that allowed the cell to remain in an 'uncommitted' (not yet differentiated state). He was successfully able to produce what he named immuno pluripotent stem cells, or iPS. iPS, when injected into immuno-deficient mice, is able to regrow a variety of types of damaged tissues. Yamanaka has been able to repeat this experiment with human cells, despite some concerns about some of the genes possessing cancer-causing potential.

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