MicroRNA in Human Brain Diseases

When were microRNAs first discovered? Which diseases can be treated using microRNAs? Assistant Professor of Neurology at Harvard Medical School, Anna Krichevsky, speaks on why microRNAs have not yet been introduced into clinics.

We started to think about microRNA functions as soon as microRNAs were discovered in 2001. Almost immediately it was apparent that microRNAs are involved in development, in brain development, and in cell differentiation. When you see that gene or genes are involved in differentiation, in cell-specification it ultimately leads you to ask a question about disease, because in many diseases normal cellular processes involved in development and differentiation are disorganized.

My lab is really interested in the basic biology of these oncomiRs, oncogenic microRNAs, in brain cancer. We are also interested in therapeutic or translational applications of this that we can develop based on our basic biology. MicroRNAs can be targeted means we can develop tools to inhibit microRNA that is oncogenic or that we believed drives the tumor progression. Because the molecules are small, their inhibitors are also small. Perhaps this gives us some advantages to deliver these molecules, especially to some systems. Of course delivery to the brain, which is the organ of our interest is the most challenging topic. It’s very difficult to deliver anything to brain.

Some people ask the question why microRNAs are still not in clinics? Why aren’t there any microRNA-based drugs clinically used? You have to remember that it’s a very, very new field. MicroRNA were discovered only 12 years go. In biology, and especially in medicine it usually takes much longer to go from target development to clinical trials, from stage I to stage III. I would say twelve years is not a long time. It’s already clear that microRNA should be developed and brought to clinics, as they have potential, but it will take maybe 5 to 10 years to have the first microRNA-based drugs moving from lab work to clinics.