A CSF Outflow Ex Vivo Model
Future Study to Include Topological Examination, Search for Aquaporins
A human CSF outflow ex vivo model has also been created for the first time at Ohio State. Another member of the Gryzbowski/Katz research team and the lead author on this study, Shelley Glimcher, B.S., presented her work on the creation of the model, as well as ideas for future research involving the model.
Instead of using only cap cells in perfusion studies, the ex vivo model incorporates the entire arachnoid granulation structure. The role of whole tissue perfusion of the human arachnoid membrane—in other words, how CSF flows through this structure—was key in this study since it is a major component of the blood-CSF barrier and can provide insight into the mechanism that triggers idiopathic intracranial hypertension. No previous work has been done on whole tissue perfusion of human arachnoid granulations.
Ms. Glimcher noted that by measuring CSF outflow through the arachnoid granulations and micro villi simultaneously, the researchers will be able to observe interaction among all cell types, thereby gaining a better understanding of the physiology. This idea forms the basis for the ex vivomodel.
She also described how a perfusion apparatus was constructed in the lab. Donated human arachnoid granulation tissue (less than 12 hours post-mortem)
samples were cut to size and secured in a special chamber, where they were oriented for fluid to flow from basal to apical. The tissue was perfused for 16-18 hours, with pressure across the membrane in preliminary experiments ranging from 4.0 to 5.5 mm. Hg. After five perfusion runs, enough data was collected to determine that a viable ex vivo model of CSF outflow through the human arachnoid membrane had been created.
Further trials will help determine correct concentrations of tracers, which can be used to determine pore size distribution. Analysis of stained tissue sections from the arachnoid membrane will also expand current knowledge about the arachnoid granulations and the effects of CSF outflow. Plans for future study include the topological examination of different sections of the arachnoid granulations; elevated pressure perfusions runs; the use of microparticles to determine where and how much of the fluid is perfusing across the membranes; and the staining of tissue for the proteins which control water movement (aquaporins).