Production of terminally differentiated neuroblastoma cells in culture.

The use of fetal central nervous system (CNS) tissue in neural transplants has ethical, availability and some biological limitations. In order to overcome these problems, homogeneous populations of specific neurons in vitro should be established. Transformed nerve cells such as neuroblastoma cells (NBP2) in culture can serve as one of the sources of donor neurons in neural transplants provided they can be induced to differentiate terminally. This study showed that treatment of murine neuroblastoma (NBP2) cells with 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (R020-1724, an inhibitor of cyclic nucleotide phosphodiesterase), and β-carotene for a period of 3 days followed by X-irradiation with 20 Gy or above produced 100% terminally differentiated cells. These differentiated NB cells had long and extensive neurites, contained elevated levels of tyrosine hydroxylase (TH) activity and very low levels of MHC class I and II antigens, and were non-tumorigenic. The viability of differentiated NB cells when determined on the criteria of attachment efficiency, re-extension of neurites and presence of TH after replating was only 9%. This was in contrast to the trypan blue exclusion technique which showed that over 90% of differentiated NB cells in culture were viable.