Assembly of a tumor microtissue by stacking normal and cancer spheroids on Kenzan using a bio-3D printer to monitor dynamic cancer cell invasion in the microtissue

In the present study, a tumor microtissue was assembled by precisely stacking normal and cancer cell spheroids on Kenzan (microneedle array) using a spheroid stacking type bio-3D printer. This is the first study to non-invasively observe the dynamic behavior of GFP-tagged cancer cell invasion in the microtissue assembled by a spheroid stacking type bio-3D printer. First, the cancer cell spheroid was prepared using 10 % cancer cells (MCF-7 expressing GFP) and 90 % normal cells (70 % HNDF and 20 % HUVEC). The normal cell spheroid was prepared using 100 % normal cells (80 % HNDF and 20 % HUVEC). The tumor microtissue was then assembled on Kenzan by placing 1 cancer cell spheroid in the center position of the microtissue and 8 normal cell spheroids around it. 9 spheroids stacked on Kenzan were fused into 1 tumor microtissue after 24 hours of culture. The green fluorescence derived from cancer cells spread from the central position to the entire area of the tumor microtissue. The spread dynamics of cancer cell-derived GFP fluorescence can be used as a simple measure to evaluate cancer cell migration/invasion and response to anticancer drugs.