Here we present a new technique to quantitatively characterize
malignant glioma invasion in a syngeneic mouse model. The GL261 mouse
malignant glioma cell line was injected intracerebrally into the C57B1/6 black mouse and allowed to propagate for 10 or 17 days, followed by
euthanasia of the animal, harvesting of the brain, fixation, and serial sectioning. Histologic examination was performed and the primary
tumor mass and discontinuous sites of
tumor invasion were traced on digital images of serial microscopy sections, followed by analysis of the invasion characteristics using a custom-written MATLAB program. We found a significant increase in the number of discontinuous
tumor invasion sites and in the distance of these sites from the
tumor centroid in mice that were euthanized
at 17 days post-
tumor cell injection, as compared to mice euthanized
at 10 days. Furthermore, a scatter plot analyses indicated that the invasion site data could be grouped based on the characteristics of area and distance from the
tumor centroid to reveal significant differences between the two experimental groups of mice. This quantitative method will allow a future in vivo analysis of invasion characteristics in
glioma cells expressing altered levels or function of invasion genes, and of new
therapy targeting invading
glioma cells.