New hES Cell Purification Technique
UCSF researchers are reporting the 1st success in rapidly purifying 1 type of embryonic stem cell from a mix of many different types of embryonic stem cells in the culture dish. The technique, which avoids the need to genetically alter the cells to distinguish them, is a key advance for obtaining the appropriate cells for repairing specific damaged tissues. The new strategy links 2 existing technologies for the 1st time:
- To efficiently sort them at a very high rate, a procedure known as “high throughput” processing,
- The ability to identify specific embryonic stem cell types in a culture of different embryonic stem cells, and a way
The research finding is currently published online in the journal “Stem Cells and Development,” and will appear later this year in a print edition of the journal.
- Embryonic stem cells, which replicate indefinitely in the culture dish, are capable of forming almost any tissue in the body.
- Over time, they begin to specialize as specific cell types, such as cardiomyocytes of the heart or neurons of the brain.
- One goal for stem cell therapy is to be able to identify cells that have begun to specialize in a particular way so that they could serve as a source of cells to repair specific damaged tissues.
While embryonic stem cell cultures are made up primarily of cells that have begun to differentiate, they also include cells that remain unspecialized, and thus have the capacity to form tumors, called teratomas.
- Scientists have attempted to purify stem cells whether to eliminate those with the potential to form teratomas or to isolate specific embryonic stem cell types-by using viruses to insert DNA into the stem cells’ genes,
- This technique allows researchers to distinguish one type of cell from another, but this genetic engineering approach carries the risk of altering the natural makeup of the stem cells.
The UCSF scientists used a different strategy:
- They identified cells that can form teratomas by searching for a telltale snippet of DNA in the tumor cells’ genes,
- They chemically tagged these cells without altering them, and the cells were then removed on the basis of this temporary molecular tag,
- They reported separating out the desired stem cells from the teratoma-forming cells at a rate of about 25,000 cells per second.
The researchers say they expect the same approach could be used to separate and purify different types of cells as they advance from the stem cell state into neurons, heart cells or any other type of tissue needed for future stem cell therapy.
The research was supported in part by the state-funded California Institute for Regenerative Medicine, or CIRM. The technique has been disclosed to the UCSF Office of Technology Management for potential licensing, as well as to CIRM.
- In the technique reported, the scientists introduced into a stem cell culture a pair of DNA snippets containing part of a gene, called Oct4, which is essential to all embryonic stem cells.
- The gene also allows cells to form teratomas, but it is not active once a stem cell starts down the road to becoming a specialized cell type. (HWM and US Fed News – HT Syndication)