Ultrastructural, functional and biochemical characteristics of mouse and human neuroblastoma cell lines

Abstract

Three commercially available neuroblastoma cell lines were analyzed to determine their ultrastructural, functional and neurochemical characteristics. The cell lines were Neuro-2a and NB41A3, derived from mouse neuroblastoma, and IMR-32, derived from a human neuroblastoma. Ultrastructurally, the neuroblastoma exhibited two major differences. Both mouse neuroblastoma cell lines contained virus-like particles, whereas the human neuroblastoma was free of virus particles. Scanning electron-microscopy revealed that the external morphology in the mouse cell lines was heterogeneous, suggesting the presence of more than one cell type, while the external morphology of the human cell line was homogeneous, suggesting the presence of a single cell type. Neurochemically, choline acetyltransferase, tyrosine hydroxylase and glutamate decarboxylase, synthetic enzymes for acetylcholine, catecholamines and γ-aminobutyric acid, respectively, were present in each cell line. Mean choline acetyltransferase activity was highest in NB41A3, but differences in this activity among the three lines were not statistically significant. Tyrosine hydroxylase activity in IMR-32 was significantly higher than in the mouse neuroblastoma cells. Glutamate decarboxylase activity was equivalent in all three cell lines. Functionally, each cell line was tested to determine its ability to form cholinergic synapses on cultured striated muscle cells. Only the IMR-32 cells formed appreciable numbers of synapses with muscle cells as detected by electrophysicological recording. The delineation of several characteristics of these three neuroblastoma cell lines will allow other investigators to choose the most appropriate of these cell lines for their studies. The heterogeneity of cell types of the mouse neuroblastoma may compromise biochemical measurements as each cell type may have different characteristics. Since only the IMR-32 form cholinergic synapses and have no more choline acetyltransferase activity than the other two cell lines, the presence of this enzyme is not a reliable marker for the ability to form synapses.