Long-term culture of organotypic multicellular glioma spheroids: a good culture model for studying gliomas.

Gliomas, as well as other solid tumours, contain tumour stroma composed of connective tissue, macrophages, capillaries and other non-cellular constituents. Therefore, a homogeneous culture of tumour cells alone, as is often used as a culture model for gliomas, is not ideal to study all aspects of gliomas. In the present study we describe an alternative culture model, i.e. organotypic multicellular spheroids (OMS), that histologically closely resembles the tumour in vivo. Glioma explants, obtained at surgery from five patients, were cultured on agarose to form OMS, which were cultured for up to 16 weeks. At regular intervals, OMS were fixed and histological and immunocytochemical analyses were carried out. The histology as well as the immunocytochemical characteristics of the OMS proved to be almost unchanged after a culture period of 16 weeks. In contrast to monolayer cultures, glial fibrillary acidic protein (GFAP) expression in the OMS is preserved after 16 weeks of culture. However, in OMS from three out of five patients, small GFAP-negative cells appeared in the outer cell layers between 1 and 2 weeks of culture. Furthermore, after about 6 weeks of culture, the capillaries disappeared from the OMS. After prolonged culture, tumour cell heterogeneity, the cellular composition, and the histology of the OMS still closely resembled the tumour in vivo. It is suggested that OMS provide a good long-term culture model for the study of gliomas.