Experimental models relating to human glioblastoma multiformes (hGBMs) involve the intracranial or intracerebral injection of human GBM cells into nude mice or rats. The aim of the present study was to compare a number of biological characteristics of hGBMs as opposed to experimental GBMs obtained by grafting either human U87 or U373 glioblastoma cells into the brains of nude mice. Biological assessments involve four distinct sets of parameters, i.e. i) the determination of the nuclear DNA content, ii) the determination of proliferative activity, iii) the assessment of p53 nuclear phosphoprotein immunohistochemical reactivity, and iv) the assessment of GFAP, VIM, LEU-7, S-100 and CAT D protein immunohistochemical reactivity. While most of the human glioblastoma multiformes (hGBMs) under study were immunohistochemically reactive to GFAP, S-100, LEU-7 and VIM as indeed were the experimental U373 GBMs, the U87 ones were reactive to VIM only. Furthermore, the U87 GBMs appeared to be more aggressive than the U373 ones since the former were associated with a shorter tumor-bearing mouse survival time than the latter. Such aggressiveness was further associated with a proliferative activity and a cathepsin D immunoreactivity, both of which were markedly higher in the U87 GBMs than in the U373 GBMs. These two experimental GBM models also exhibited tumors which were predominantly diploid. The present study shows that it is possible to set up experimentally in vivo models which strongly mimic human glioblastoma multiformes. Such models consist of grafting human glioblastoma cell lines, namely U87 and U373, into the brains of nude mice. However, while it is true that experimental GBMs closely resemble the hGBMs with respect to some biological characteristics, they also differ in many other significant biological characteristics.

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