Efficacy of recombinant Bacillus Calmette-Guerin containing dltA in in vivo three-dimensional bio-printed bladder cancer-on-a-chip and ex vivo orthotopic mouse model

Purpose: We investigated the efficacy and optimal dosage of recombinant Bacillus Calmette-Guerin-dltA (rBCG-dltA) in a high-throughput 3D bio-printed bladder cancer-on-a-chip (BCOC) and orthotopic bladder cancer mouse model.Materials and Methods: We fabricated high-throughput BCOC with microfluidic systems, enabling efficient drug screening. The efficacy of rBCG-dltA was evaluated using BCOC by the cell viability assay, monocyte migration assay, and measuring cytokine levels. The anti-tumor effect was compared using the orthotopic bladder cancer mouse model.Results: The cell proliferation rates of T24 and 253J bladder cancer cell lines (mean +/- standard error) were measured at three days after treatment. In T24 cell line, there was significantly decreased T24 cells compared to control at rBCG 1 multiplicity of infection (MOI) and 10 MOI (30 MOI: 63.1 +/- 6.4, 10 MOI: 47.4 +/- 5.2, 1 MOI: 50.5 +/- 7.5, control: 100.0 +/- 14.5, p<0.05). In 253J cell line, a statistically significant decrease in 253J cell count compared to control and mock BCG 30 MOI (30 MOI: 11.2 +/- 1.3, 10 MOI: 22.5 +/- 2.3, 1 MOI: 39.4 +/- 4.7,Mock: 54.9 +/- 10.8, control: 100.0 +/- 5.6, p<0.05). The migration rates of THP-1 cells showed increased patterns after rBCG-dltA treatment in BCOC. The concentration of tumor necrosis factor-alpha and interleukin-6 after rBCG-dltA 30 MOI treatment was higher than control in T24 and 253J cell line.Conclusions: In conclusion, rBCG-dltA has the potential to have better anti-tumor activity and immunomodulatory effects than BCG. Furthermore, high-throughput BCOCs have potential to reflect the bladder cancer microenvironment.