Don’t miss! Totally ethical embryonic stem cells! Now 100 times more for 4 times less!

This news was published already on April 8^th this year, but I have only recently come across it.

Induced pluripotent stem (iPS) cells have been a very sexy topic since they were first generated in 2006. They are very much like embryonic stem cells, but their generation involves no embryo killing and thus they completely circumvent the whole ethical debate. To generate these cells, in a nutshell, scientists took some fibroblasts (adult cells) and treated them with retroviral vectors (a sort of molecular syringes) which carried genes that can make a cell go into embryonic – or pluripotent – state. This way they reprogrammed the fibroblasts to return to embryonic-like state. But the efficiency of this procedure was extremely low, as only about 0.02% of human fibroblasts turned into iPS cells (1). And when you think about it, it’s not much of a surprise. To reprogram a cell, you need three or four genes, which is three or four separate viral vectors. If a viral vector infects only, say, 20%, of a cell population, then two vectors will infect only 20% of that 20%, and so on. On top of that, not all infected cells will give in to the effect of the introduced gene. In the end, you end up with only a small fraction of cells that both took up all the genes and underwent successful reprogramming.

In the publication that I am going to comment on here (2), the scientists took a slightly different approach. They also used the retroviral vector as a gene delivery tool. However, instead of four, there were able to use only one retroviral vector. Normally, it’s hard to fit many genes into one vector, but these guys used only two – not three or four – genes. And on top of that, they were a very different kind of genes coding so-called miRNA. Now, unlike other genes, miRNAs don’t get translated into proteins but they can be very powerful when it comes to regulating levels of other proteins. And on top of that – miRNA genes are far smaller than protein genes, so it was not so much of a challenge to fit two of them into one vector. Effectively, using this technique they were able to generate iPS cells with about 100-fold higher efficiency!

This is pretty exciting but still pretty recent. If it is going to repeated by other researchers, chances are, this will become the standard protocol for generation of iPS cells. Which in turn hold a great promise for serving as good in vitro models of genetic disorders and maybe – in future – for personalised regenerative medicine.

1. Induction of Pluripotent Stem Cells from Adult Human Fibroblasts by Defined Factors. 
2. Highly Efficient miRNA-Mediated Reprogramming of Mouse and Human Somatic Cells to Pluripotency.