A working process for cloning stem cells from existing human cells has finally been discovered by a team at Oregon Health & Science University.
These stem cells were created by reprogramming healthy skin cells, a goal that has eluded researchers around the world for years. It's the first key step in developing medical procedures for replacing dying or injured cells with new ones to stave off disease and age. That could mean growing a new liver, or kidney or heart, in the lab for an organ transplant, or even repairing the brains of those suffering with diseases like Parkinson's.
The team was led by Shoukhrat Mitalipov from the reproductive and developmental sciences department of the Oregon National Primate Research Centre. He said: "A thorough examination of the stem cells derived through this technique demonstrated their ability to convert just like normal embryonic stem cells into several different cell types, including nerve cells, liver cells and heart cells. Furthermore, because these reprogrammed cells can be generated with nuclear genetic material from a patient, there is no concern of transplant rejection." "While there is much work to be done in developing safe and effective stem cell treatments, we believe this is a significant step forward in developing the cells that could be used in regenerative medicine."
The technique Mitalipov and his team used is called "somatic cell nuclear transfer" -- as you can see in the video, it essentially involves sucking out the DNA from an adult cell and inserting it into the empty nucleus of a donor egg. This creates a clone of the original cell, and is in fact the first step in the cloning method used to create animal clones like Dolly the sheep.
However, in its therapeutic mode, the new cells can be grown as replacements for the original type of cell. That objective hasn't been reached until now as human eggs are extremely fragile compared to many of the animals which we have cloned. That Mitalipov and team have succeeded is down to research on primates, and adapting primate stem cell research to humans.
As a cell divides after fertilisation, it undergoes several transformations as it prepares to split and multiply. The metaphase is the moment just before a cell splits, as the chromosomes align alongside each other in the very centre of the cell so that, when it splits, one goes one way as another goes the other, each taking the full copy of the genetic code. The researchers managed to stall the metaphase while the cell underwent nuclear transfer, effectively giving the new chromosomes time to get settled before the metaphase finished and cell division proceeded.
An added bonus is that the eggs used have not been fertilised, so there won't be any debates over the ethics of embryonic stem cells as we have seen in the US in the past. While the researchers placed skin cell nuclei into the receptor egg cells, the method is conceivably similar for any other kind of cell.
And, while it may sounds like the first step towards a practical method for cloning humans, the Mitalipov has made it clear that's not the aim. "Our research is directed toward generating stem cells for use in future treatments to combat disease. While nuclear transfer breakthroughs often lead to a public discussion about the ethics of human cloning, this is not our focus, nor do we believe our findings might be used by others to advance the possibility of human reproductive cloning."
The research has been published in the journal Cell.