Cytogenetic follow-up from direct preparation to advanced in vitro passages of a human malignant glioma.

In order to evaluate which cytogenetic evolutionary patterns take place during the in vitro establishment of a permanent glioma cell line, cytogenetic follow-up was performed on direct preparations and primary cultures from a malignant astrocytoma and on serial passages for more than 2 years of in vitro propagation. Sixteen passages were studied, and the presence of a marker chromosome in direct preparations and after in vitro growth permitted us to identify the clonal evolution of the resulting permanent cell line. Near-triploid cells present in the direct study became the main cell population in vitro; chromosomal losses and the acquisition of a few new marker chromosomes were also characteristic features, leading to a stable modal number of around 60 chromosomes in the last passages analyzed. The results provide new evidence of the existence of more than one pattern of chromosomal evolution during the in vitro establishment of human gliomas.