Cytology, growth characteristics and cellular alterations following SV40-induced transformation of human foetal brain cells derived from a Gm2 gangliosidosis and control

Abstract

Cell cultures were derived from the cerebra of a control and a Gm2 gangliosidosis (Tay-Sachs disease (TSD)) foetus. Both cell lines were identified as astrocytic, based on the ultrastructural demonstration of glial fibres. The control culture exhibited morphological differentiation when exposed to dibutyryl cAMP, a finding which was not observed with the TSD cells. The TSD culture demonstrated the pathobiological features of the disease, which included the absence of hexosaminidase A, increased concentration of Gm2 ganglioside and the detection of membranous cytoplasmic bodies by electron microscopy. Control and TSD cells were exposed to SV40 virus, resulting ultimately in the isolation of transformants which differed from the parental cell types in morphology, growth rate and greatly accelerated cell death. Both control and TSD cell lines have been in propagation for over 200 subcultures and the transformants were identified as astrocytic, based on the retention of characteristic glial fibres. The control culture demonstrated a chromosome range of 34–63, with a mean of 47. In contrast, the TSD transformants exhibited a range of 50–107 and a mean of 74. Transformed lines retained their parental hexosaminidase isoenzyme profiles; Hex A and B in control, and Hex B in TSD cells. Membraneous cytoplasmic bodies persisted in the TSD line. Neither line could be induced to differentiate after exposure to cAMP. Additionally, they had a population doubling time of under 85 h and failed to release infectious virus particles. Significant alterations in the total quantity and distribution profile of gangliosides were noted following viral transformation. A large increase in the percentage of Gm3 and a more modest increase in Gm2 were detected. In contrast, transformed lines were characterized by substantial reduction in the percentage of glucosamine-containing Gm2 and polysialoganglioside. Additionally, cultures exhibited a characteristic reduction in ganglioside content after transformation. The in vitro transformation of human brain cells has resulted in the derivation of permanent astrocytic lines which are, by virtue of their rapid growth rate and long-term survival, uniquely suited and adapted to the large scale in vitro production of substantial quantities of cells required for extensive biochemical study. Significantly, those characteristics which are unique to the Gm2 gangliosidosis storage disease have been retained in a permanent model CNS cell line.