Somewhere in your body resides a rare group of cells that can give rise to various specialized cell types of the body-the muscles cells that make your heart beat, the red blood cells that carry oxygen. Unlike mature cells that cannot replicate, these cells can make multiple copies of themselves indefinitely.
It is these two properties of stem cells-pluripotency and self-renewal-that continue to intrigue scientists and inspire potential therapies. Here at U of T, a tradition of stem cell research from the 1960s lives on despite political and scientific setbacks, in hopes of developing stem cell therapies that can restore cells and tissues damaged by injury or disease.
“We have got people working on all different types of tissue,” says Dr. van der Kooy, a professor of medical biophysics and a leading stem cell researcher. Whether embryonic or adult, almost every aspect of the stem cell is being investigated right here-from what internal and external signals make a stem cell become a brain cell, to finding where stem cells reside and how to better derive stem cells from different sources.
For van der Kooy, whose research located stem cells around the iris of the eye that can differentiate into photoreptors, his current interests lie in unraveling how embryonic stem cells develop into the more restricted, adult brain stem cells.
A few offices down from van der Kooy, Dr. Peter Zandstra, a professor in the Institute of Biomaterials and Biomedical Engineering, is interested in how stem cells “talk” to each other. Once a stem cell ‘differentiates’ into a specific cell type-say a muscle cell-it must tell other stem cells what to do or what not to.
“Cells communicate through soluble signaling networks,” explained Zandstra. “Differentiated progenies send instructions back to the stem cell to grow or differentiate.” By identifying and manipulating the factors secreted by cells and stem cells, Zandstra hopes to control stem cell fate so that they can differentiate embryonic stem cells into blood or cardiac cells for therapeutic purposes.
To do so, Zandstra and his team designs bioreactors, devices that mimic the optimal cellular microenvironment for stem cell growth. To date, his team has designed large-scale bioreactors for the production of cardiac stem cells, which hopefully will be used in transplantation.
While bone marrow and umbilical cord blood are the two most readily available sources of human adult stem cells, Dr. John Davies, professor at the Institute of Biomaterials and Biomedical Engineering, has recently discovered an alternative source of adult stem cells. Around the blood vessels of the human umbilical cord are cells called HUCPVCs, or human umbilical cord perivascular cells, and Davies was the first to characterize the methods to extract and store these cells.
One of the most exciting traits of HUCPVCs is that they are abundant in mesenchymal stem cells, a type of stem cell currently used in treatments such as tissue generation for wound healing.
“The same range of possibilities is available for our HUCPVCs,” explained Davies. Clinical therapies will benefit from the higher frequencies of mesenchymal stem cells in HUCPVCs than in cord blood and bone marrow where cells were harvested until now.
A few blocks south of College St., stem cell research stretches in the hospital district-here, it is used to better understand complicated diseases like brain cancer.
“Is there a precursor cancer cell that is playing the same role as a normal stem cell?” asks Dr. Peter Dirks, a neurosurgeon at the Hospital for Sick Children. His research looks for neural stem cells in brain tumors that drive tumor growth much like stem cells drive normal organ growth. By identifying the cells in brain tumors that have this “cancer stem cell” property, Dirks and his team have provided insight into what type of cells are crucial targets for cancer therapies.
Within a community that prides itself on cutting-edge science, van der Kooy and other stem cell researchers find the close-knit dynamics of Toronto’s stem cell group as enjoyable as it is necessary in the development of good science.
“It’s one of the best environments to do stem cell research,” said van der Kooy.
