Leveraging microfluidics for reproducible high lentiviral transduction efficiency

In cell culture bioprocesses, noise often overpowers signal. Cell culture bioprocesses suffer from batch-to-batch variability, largely due to manual multi-user interventions. This affects typical bioprocesses indispensable for cell and gene therapy applications, such as transduction. Conventional lentiviral transduction processes methods typically face challenges concerning efficiency. Often, it requires high multiplicity of infection (MOI) to reach acceptable levels of transduction efficiency, consequently resulting in high costs due the costs of viral reagents. Moreover, a high MOI can also increase risks of toxicity. A solution is needed to lower MOI while maintaining high efficiency, whilst also maintaining high precision and reproducibility.

Without precision, achieving consistently high efficiency remains a challenge. In this study, we  leverage the benefits of a microfluidics-based bioreactor, designed with low fluid heights and large surface to volume ratios (S/V), where the geometric form-factor microenvironments enhance precision cell-lentivirus interactions. We demonstrate the feasibility using an exemplar CAR-T transduction on Primary T-cells  with CD19 lentiviral vector. Using a design of experiment (DOE) methodology, we demonstrate that at lower MOIs,  we obtain 2-3 fold transduction efficiency greater than conventional vessels, thereby contributing to lower experimental costs with a higher quality cell product.

We also demonstrate the consistency of the process in these precision bioreactors using a multi-operator experiment. We show evidence of comparability in terms of cell count, viability, expansion and transduction efficiency amongst multiple operators; therefore demonstrating the robustness of the microfluidics-based bioreactor.  Having a precision bioreactor helps de-risk issues related to interoperability, thereby ensuring reproducibility and consistency in cell data.