The spleen in stroke patients undergoes dynamic changes of contractions and re-expansion in the days following the onset of stroke symptoms, releasing inflammatory cells and possibly contributing to further brain injury, according to Medical School researchers.
The results of the prospective clinical study were published in the Dec. 26, 2012, issue of the International Journal of Stroke.
“We’ve known from animal studies that the spleen contracts after stroke, followed by the release of inflammatory white blood cells leading to secondary brain injury, so we wanted to observe what happens to the spleen in patients after a stroke,” said Dr. Sean Savitz, principal investigator and professor of neurology. “This is a completely understudied area. The spleen is not normally an organ that neurologists or neuroscientists pay attention to. This was our initial attempt to look at the size of the spleen in stroke patients.”
The spleen is part of the lymphatic system, which fights infection by releasing white blood cells. It also helps control the amount of blood in the body and destroys old and damaged cells.
The study included 29 stroke patients and 20 healthy volunteers. The research team performed daily abdominal ultrasounds to measure the size of the spleens. In the stroke patients, spleens initially reduced in size and then re-expanded. The spleens of the healthy volunteers showed minimal variation in daily spleen size compared with the stroke patients.
Savitz said the study demonstrated a good correlation between the contraction of the spleen and the amount of white blood cells in the body. The results also suggested that some patients whose spleens contracted for a longer period of time, releasing more inflammatory white blood cells, had poorer clinical outcomes. Further studies will be needed to confirm and explain these early findings, Savitz said.
Savitz and fellow researchers became interested in studying the spleen after animal studies at showed that stem cells administered intravenously after a stroke travelled to the spleen, as well as to the brain.
“The big question was why?” said Savitz, who is director of the Stroke Program and an attending physician at Memorial Hermann-Texas Medical Center. “Emerging work by our group and other researchers suggest that some types of stem cells have a dampening effect on the inflammatory response emanating from the spleen. The spleen is a possible target in the future for treating stroke.”
The research, funded by a grant from the Senator Lloyd and B.A. Bentsen Center for Stroke Research at UTHealth, will continue, Savitz said. Savitz’s research team at UTHealth included first authors Dr. Preeti Sahota and Dr. Farhaan Vahidy.
–Deborah Mann Lake, Office of Advancement, Media Relations