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Strokes are one of the most common causes of death disability in adults. (Jin) There are two main types of strokes: hemorrhagic strokes and ischemic strokes. A hemorrhagic stroke is internal bleeding within the brain, usually due to a ruptured blood vessel. An ischemic stroke, which is responsible for approximately 80% of all strokes, is due to an occlusion within a blood vessel. These occlusions may be caused for a variety of reasons, although they are most often due to blood clots.

PowerPoint representation of a stroke: Stroke.



Traumatic brain injuries are also a leading cause of death. Traumatic brain damage may be caused by almost any strong force to the head. Such instances include car accidents, tripping and falling, objects falling on head, etc. When such a force acts on a person’s head, their brain may strike the skull and cause tissue damage.

PowerPoint representation of head trauma: Trauma


When the brain is physically damaged, as is often the case with strokes and trauma, there are reparatory mechanisms that attempt to reverse the damage. It is believed that neurogenesis may be one such reparatory mechanism. Studies have shown that newly born neurons may migrate to sites of damage in an attempt to fix the damaged area of the brain. Some studies suggest that this type of neurogenesis may happen in situ. In situ neurogenesis is the proliferation of newly born neurons within the damaged area of the brain. Other studies suggest that when new neurons are needed from the subventricular zone (the most common site of neurogenesis), they migrate to the appropriate area of damage instead of their usual targets. It is important to note that, even if trauma and strokes do induce the production of new neurons, it is not clear if these new neurons are functionally integrated within the brain. Several studies suggest that growth factors play an important role in stroke and trauma induced neurogenesis. Age and genetics affect which growth factors may be present, and as such, different people of different ages may be able to recover from trauma and strokes at different rates.

Powerpoint representation of neuronal migration to damaged tissue: Migratory Stream.

(click on the image for higher resolution) Image by Chris Blum

Stem cells could repair stroke related brain

Stem Cells and Stroke : Acknowledgments to

*Please note: This page should not be taken as professional medical advice


Chen X. et al (2003), Jin K. et al (2006)Kernie SG. et al (2009),

Nakayama D. et al (2010)Ohira K. et al (2010)Shen CC. et al (2010)Yoshimura S. et al (2001).

-Page by Chris Blum