Researchers discover potential way of expanding cells

A new "master control gene"  for human blood stem cells has been discovered by Canadian and Italian stem cell scientists and manipulating its levels could probably produce a way to expand these cells for clinical use.

The results of this study could introduce a new model for the regulation of human blood stem cells, states principal investigator, Dr John Dick, who is a senior scientist at University Health Network's McEwen Centre for Regenerative Medicine and Ontario Cancer Institute (OCI), the research arm of the Princess Margaret Cancer Centre.

Scientists found that for the first time in human blood stem cells, a new class of non-coding RNA called miRNA offers a new way for manipulating these cells, which gives the opportunity to expand them for therapeutic uses, explained Dr Dick.

Isolating the human blood stem cell in its purest form in 2011, Dr Dick changed it into a single stem cell able to regenerate the whole blood system, which paved the way for clinical uses.

The expert also identified leukaemia stem cells in 1994 and colon cancer stem cells in 2007.

OCI lead author Dr Eric Lechman explained the research team took away a master control gene, named  microRNA 126 (miR-126). This typically controls the expression of hundreds of other genes by keeping them silenced, which leads to the keeping the stem cells in a non-dividing latent condition.

By using a specifically designed viral vector, the process was to initiate excess numbers of miR-126 binding sites into the stem cells.

Like a sponge, the virus sucked up the particular miRNA in the cells which then allowed the expression of typically repressed genes to become prominent. Then a long-term expansion of the blood stem cells was evident, minus overtiredness or malignant transformation, explained Dr Lechman.

"We've shown that if you remove the miRNA you can expand the stem cells while keeping their identity intact. That's the key to long-term stem cell expansion for use with patients," said Dr Dick.

Posted by Neil Clark