Biology Without Borders: Tulane University - Research with Stem Cells and Stroke

I’m Gustavo B. Vallim, exchange student from Brazil. I’m Biomedical Science student at Federal University of Alfenas - Brazil and in March I left my country to continue my studies at Loyola University New Orleans. I have worked with Dr. Jean-Pyo Lee in the Center for Stem Cell Research and Regenerative Medicine at Tulane University since last September.

Stem Cells research always drew my attention and I had the great opportunity to join to this group. These cells can be induced to become tissue- or organ-specific cells with special functions. There are embryonic stem cells and "somatic" or "adult" stem cells. Moreover, there is a new type: induced pluripotent stem cells (iPSCs) that are some specialized adult cells "reprogrammed" genetically to assume a stem cell-like state. In my research we transplant human neural stem cell (hNSC) into the brain of mice after an induced ischemic stroke.

Stroke is the second leading cause of death and a major cause of disability in the world. A stroke occurs when the brain is deprived of the oxygen it needs due to an interruption of its blood supply. Without oxygen brain cells die. The oxygen deprived area of brain tissue is called an infarct. Depending on what area of the brain has been affected, a stroke can cause problems with speech, behavior, thought patterns and memory, and may result in permanent brain damage, disability or death.

There are some ways to treat the stroke, but sometimes the treatments are not successful. For example, the use of tissue plasminogen activator (tPA) as a thrombolytic treatment in ischemic stroke is approved by the US Food and Drug Administration (FDA), but it has a narrow therapeutic window. tPA dissolves the blood clot that is blocking the artery and restores the blood flow to the brain. However, if it is used after 3 hours of the onset of stroke, tPA can increase the incidence of intracerebral hemorrhage, a severe complication of stroke that is associated with high mortality. We believe that stem cells can be a new treatment and/or be used to extend the therapeutic window for tPA therapy.

So, how we induce the mice to stroke? In summary, with a support of a microscope we do a surgery in the anesthetized mice called Middle Coronary Artery Occlusion (MCAO). As the name says, we block this artery that supplies blood to a specific area in the brain causing infarct in this territory. We open the ventral region of neck in the mice and we find the External Carotid Artery (ECA) where a monofilament is introduced until blocks the MCA in the brain. After one hour the blood flow is restored and, in the next day, we do a transplantation of stem cell into the brain.