Therapeutic Cloning Proof of Principle in Mice
Scientists have created mouse cloned embryos, derived stem cell lines from them, and injected them into the Parkinson's diseased mice from which they were taken. From the story:
It is the first time "therapeutic cloning" has been used to treat the devastating disease. Cloned cells are so useful because they are genetically identical to the patient, and are not rejected. Although carrying out the procedure on humans is a long way off, in the short term scientists hope to test new drugs on brain cells from Parkinson's patients grown in the lab...Well, that's overstating it a bit, but never mind. It is worth noting, however, that human cloned ESC lines have not yet been created. Moreover--and the Telegraph did mention this in the story--IPS cells, taken from Parkinson's patients, could do the same thing for drug testing--and far easier, more efficiently, and without the controversy associated with human cloning.
The study, published in the journal Nature Medicine, suggests the same method of cloning used to create Dolly the sheep can be used to grow a patient's own brain tissue and repair damage done by the debilitating disease.
But beyond that little point, there was much in this study that would make any direct human clinical application a very long way off. This from a scientist friend (and opponent of cloning) who has studied the original paper:
- The mice did show improvement. They were only allowed to live 11 weeks after transplant.And that's with mice. It would be even more "complex" with humans.
- They note that this procedure is "technically complex,"
which is a huge understatement. This still requires a HUGE number of oocytes to get a single cell line! In total, 187 ntESC lines were produced from 5099 oocytes, for cloning, 24 mice total. [Me: At present, human eggs in that quantity are extremely difficult to find, and the efficiency would likely be far less.]
- Most of the cells produced that they tested showed chromosomal
- 1 out of every 6 mice showed "graft overgrowth." "Graft overgrowth" is reminiscent of the problems experienced by Parkinson's patients treated with fetal tissue. 15-25% of the patients had worsened, even
uncontrollable symptoms. Characterized by NYTimes as "devastating"; "the patients writhed and jerked uncontrollably"