An in vitro screening system for anti-cancer drugs cannot exactly reflect the efficacy of drugs in vivo, without mimicking the tumour microenvironment (TME), which comprises cancer cells interacting with blood vessels and fibroblasts. Additionally, the tumour size should be controlled to obtain reliable and quantitative drug responses. Herein, we report a bioprinting method for recapitulating the TME with a controllable spheroid size. The TME was constructed by printing a blood vessel layer consisting of fibroblasts and endothelial cells in gelatine, alginate, and fibrinogen, followed by seeding multicellular tumour spheroids (MCTSs) of glioblastoma cells (U87 MG) onto the blood vessel layer. Under MCTSs, sprouts of blood vessels were generated and surrounding MCTSs thereby increasing the spheroid size. The combined treatment involving the anti-cancer drug temozolomide (TMZ) and the angiogenic inhibitor sunitinib was more effective than TMZ alone for MCTSs surrounded by blood vessels, which indicates the feasibility of the TME for in vitro testing of drug efficacy. These results suggest that the bioprinted vascularized tumour is highly useful for understanding tumour biology, as well as for in vitro drug testing.
Tumor spheroids are powerful tools
for drug screening and understanding
tumor physiology. Among spheroid formation methods, the hanging drop
method is considered most suitable for high-throughput screening (HTS)
of anticancer drugs because it does not require surface treatment.
However, it still needs to increase the liquid-holding capacity because
hanging drops often fall due to the increased pressure caused by the
addition of drugs, cells, etc. Here, we report a multi-inlet spheroid
generator (MSG) enabling the stable addition of liquid-containing
drugs or cells into a spheroid through its side inlet. The MSG was
able to load additional solutions through the side inlet without increasing
the force applied to the hanging drop. The volume of the additional
liquid was easily controlled by varying the diameter of the side inlet.
Furthermore, the sequences of the solution injections were manipulated
using multiple side inlets. The feasibility of the MSG in clinical
application was demonstrated by testing the efficacy of drugs in patient-derived
cancer (PDC) cells and controlling the stromal cell ratio in the tumor
microenvironment (TME) containing spheroids. Our results suggest that
the MSG is a versatile platform for HTS of anticancer drugs and recapitulating
the TME.
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