Abstract

Multiplexed microfluidic culture device for stem cell culturing

Nicolas Szita, Professor, University College London

The development of efficient and reliable bioprocesses is of paramount importance for the production of stem cell-based therapies. The number of factors that affect stem cell fate, combined with their time-dependent optima, creates a wide and complex experimental space to investigate. This issue is compounded by the high cost of medium components, limiting the applicability of conventional culture techniques for process optimisation. To address this challenge, we previously presented a microfluidic automated culture platform that consisted of a microfabricated culture device for adherent cells, temperature and perfusion control systems and online monitoring for dissolved oxygen and culture confluence. We have further developed the design of the system to improve the robustness, ease of use, experimental throughput and control over the soluble microenvironment. The new aluminium frame was designed to house three independent culture devices. Its new slot-in assembly system allowed for easier and faster preparation of the system for culture. The stiffer frame design resulted in a larger and more uniform compression of the culture chip. This resulted in a burst-pressure 6.3 times higher than reported for the previous design. Two brackets mounted on the top frame enabled tight integration with the microscope-based monitoring system previously demonstrated. A new chip design was developed to improve flow uniformity, using tree-like structures to expand the flow. A new gas-permeable lid, using a PDMS membrane, was added to the design. Finite element modeling showed that the gas-permeable lid significantly reduced oxygen gradient formation across the culture chamber, even at higher cell densities, leading to higher and more uniform pericellular oxygen levels than in flask cultures or in the gas-impermeable lid system previously presented. Preliminary culture experiments demonstrated successful expansion of mouse embryonic stem cells for a period of 84 hours. Full ch