Wonder cure?: A colony of human embryonic stem cells.
Credit: Wikipedia
CHICAGO: A study published Monday has found that eggs from cows, rabbits and other animals are not a good source for creating embryonic stem cells, the master material that could one day replace organs and reverse degenerative diseases.
But, in the same study – published in the journal Cloning and Stem Cells – U.S. researchers made a significant advance in the cloning of human embryos, which could be a path to producing a host of patient-specific treatments.
Reprogrammed DNA
"This study shows for the very first time that cloning really works and that DNA is reprogrammed," said co-author Robert Lanza, the chief scientific officer at Advanced Cell Technology a biotech firm specialising in stem cell research.
Lanza and his team were able to replace the nucleus of a number of embryos and bring the clones to the morula stage, where they had divided into eight to 16 cells.
In the human embryos, they were able to prove that the DNA was reprogrammed because the same genes were activated as in a normal embryo.
But something went wrong when the nuclei of rabbit, mice and cow embryos were replaced with a human nucleus.
"We would get these beautiful little embryos but it wouldn't work: instead of turning on the right genes the animal eggs would turn them off," said Lanza.
Researchers had hoped that cloned animal eggs could be used to create human embryonic stem cells, which are highly versatile, primitive cells capable of developing into any tissue of the body.
Regeneration potential
The dream is to coax these cells into becoming lab-dish replacements for heart, liver, skin, eye, brain, nerve and other cells destroyed by disease, accidents, war or normal wear-and-tear.
Scientists have found two potential ways to avoid the dangers of organ or tissue rejection.
The most promising method is to reprogram skin cells so they behave like embryonic stem cells. But these "induced pluripotent stem cells" (IPS) are currently created using harmful viruses and are not safe for clinical use.
Cloning embryos so that they have the same DNA or tissue type as the patient could be safe for clinical use. But researchers have not yet derived an embryonic stem cell line from a cloned embryo or found an efficient way to clone human embryos.
