In a new study appearing this month in the Journal of Neuroscience, researchers have unlocked the complex cellular mechanics that instruct specific brain cells to continue to divide. This discovery overcomes a significant technical hurdle to potential human stem cell therapies; ensuring that an abundant supply of cells is available to study and ultimately treat people with diseases.
"One of the major factors that will determine the viability of stem cell therapies is access to a safe and reliable supply of cells," said University of Rochester Medical Center (URMC) neurologist Steve Goldman, M.D., Ph.D., lead author of the study. "This study demonstrates that - in the case of certain populations of brain cells - we now understand the cell biology and the mechanisms necessary to control cell division and generate an almost endless supply of cells."
The study focuses on cells called glial progenitor cells (GPCs) that are found in the white matter of the human brain. These stem cells give rise to two cells found in the central nervous system: oligodendrocytes, which produce myelin, the fatty tissue that insulates the connections between cells; and astrocytes, cells that are critical to the health and signaling function of oligodendrocytes as well as neurons.
Damage to myelin lies at the root of a long list of diseases, such as multiple sclerosis, cerebral palsy, and a family of deadly childhood diseases called pediatric leukodystrophies. The scientific community believes that regenerative medicine - in the form of cell transplantation - holds great promise for treating myelin disorders. Goldman and his colleagues, for example, have demonstrated in numerous animal model studies that transplanted GPCs can proliferate in the brain and repair damaged myelin.
However, one of the barriers to moving forward with human treatments for myelin disease has been the difficulty of creating a plentiful supply of necessary cells, in this case GPCs. Scientists have been successful at getting these cells to divide and multiply in the lab, but only for limited periods of time, resulting in the generation of limited numbers of usable cells.
"After a period of time, the cells stop dividing or, more typically, begin to specialize and form astrocytes which are not useful for myelin repair," said Goldman. "These cells could go either way but they essentially choose the wrong direction."
Overcoming this problem required that Goldman's lab master the precise chemical symphony that occurs within stem cells, and which instructs them when to divide and multiply, and when to stop this process and become oligodendrocytes and astrocytes.