Investigation of neural progenitor cell induced angiogenesis after embolic stroke in rat using MRI

Using MRI, we investigated dynamic changes of brain angiogenesis after neural progenitor cell transplantation in the living adult rat subjected to embolic stroke. Neural progenitor cells isolated from the subventricular zone (SVZ) of the adult rat were labeled by superparamagnetic particles and intracisternally transplanted into the adult rat 48 h after stroke ( n = 8). Before and after the transplantation, an array of MRI parameters were measured, including high resolution 3D MRI and quantitative T 1, T 1sat ( T 1 in the presence of an off-resonance irradiation of the macromolecules of brain), T 2, the inverse of the apparent forward transfer rate for magnetization transfer ( k inv), cerebral blood flow (CBF), cerebral blood volume (CBV), and blood-to-brain transfer constant ( K i) of Gd-DTPA. The von Willerbrand factor (vWF) immunoreactive images of coronal sections obtained at 6 weeks after cell transplantation were used to analyze vWF immunoreactive vessels. MRI measurements revealed that grafted neural progenitor cells selectively migrated towards the ischemic boundary regions. In the ischemic boundary regions, angiogenesis confirmed by an increase in vascular density and the appearance of large thin wall mother vessels was coincident with increases of CBF and CBV (CBF, P