Saturday, October 20, 2012

Organ Transplants: Have It Your Way

An article from today’s NYT science section shows how the stuff that sci-fi dreams are made of is finally becoming a reality: researchers have been able to successfully build made-to-order organs with the cells of the patient that they are being transplanted into.
Living cells are washed from rat hearts and lungs, leaving only the extracellular organ scaffolding. Image credit: New York Times
When the idea of homegrown organs was first conceived, the transplant organs were made using donor organs which had been stripped of all of the donor’s own living cells, leaving only a scaffold made of support proteins and other fibers. The scaffolds retain the same basic shape as the living organ, and so they can be re-seeded with cells and stem cells from the transplant recipient which will re-grow the organ using the scaffold structure as a rough template. This procedure is still limiting, however; although the risk of the transplant recipient’s immune system attacking the transplant is reduced because it is made of native cells, the scaffolds still need to be obtained from donated organs which are often in short supply. 
Researchers holding the synthetic organ scaffold. Image credit: University College London.
Dr. Paolo Macchiarini and his team at the Karolinska Institute in Sweden envisioned a way to avoid the need for a donor organ by creating a syntheticorgan scaffold, reducing the time spent waiting for a donor and allowing them to tailor the organ’s size and shape to their patient. Researchers at the University College London designed and built a synthetic windpipe scaffold which were seeded with cells from Andemariam Beyene, a patient of Dr. Macchiarini’s with a large and aggressive tumor growing on his windpipe. Two days after combining the synthetic scaffold with Beyene’s bone marrow stem cells, a complete synthetic windpipe was formed. Mr. Beyene’s windpipe was removed by Dr. Macchiarini along with the tumor, and replaced with the synthetic windpipe. 
The fully developed synthetic trachea two days after the patient’s stem cells were added. Image credit: University College London
Miraculously, as of today Mr. Beyene is doing well and is cancer-free. Since his success with the first transplant Dr. Macchiarini has performed a similar procedure on three other patients; two of the three patients are doing well, although the third died for reasons which have not been disclosed. 
A decade ago it was surmised that it may one day be possible to accomplish what Dr. Macchiarini and his team have achieved- and now that day has come. After last week’s announcement of the winners of the 2012 Nobel Prize in Physiology or Medicine, it is heartening that the promise of stem cells is starting to be fully realized. 

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