Three-dimensional endothelial-tumor epithelial cell interactions in human cervical cancers

Abstract

The purpose of this study is to understand the multicellular interaction between tumor epithelial (TEC) and human umbilical vein endothelial cells (HUVEC). The development of in vitro systems in which to coculture these cells as multicellular aggregates is very critical. Cell lines were established from cervical tumor cells (n = 6) and two from HUVEC (n = 2) and they were cultured as three-dimensional (3-D) multicellular-cultures using Cytodex-3 microcarrier beads in the rotating wall vessel (RWV). After a 240-h incubation, TEC and HUVEC proliferated exponentially to 4.2 x 10(7) and 2.2 x 10(7) cells/ml, respectively, without requiring a feeder layer; in contrast to the two-dimensional (2-D) cultures that average about 8 x 10(5) cells/ml. Phase contrast microscopy indicated formation of 3-D aggregates that varied in size from 0.5 to 5 mm. The size of the aggregates (1-5 mm, 6-14 microcarriers) increased over time; however, the number of aggregates (0.5-1 mm, 2-5 microcarriers) decreased over a long-term incubation (240 h) because the cells merged to form large clumps. Maximum aggregation was observed with TEC at 120 h and HUVEC at 96 h. The culture of TEC in the absence of HUVEC produced minimal differentiation in contrast to cocultures. The TEC and HUVEC as cocultures in RWV proliferated at an accelerated rate (1.3 x 10(7) cells/ml, 96 h). The TEC-HUVEC coculture presented tubular structures penetrating the tumor cell masses, forming aggregates larger in size than the monocultures and typically with greater cell mass and number. The cells were viable (trypan blue exclusion) and metabolically active (glucose utilization) until 240 h. These data suggest that RWV provides a new model that allows us to investigate the regulatory factors that govern tumor angiogenesis.