Traditional methods for manual cultivation of stem cells often lead to high variability and low consistency, making development of robust experimental protocols for stem cell research extremely difficult. This has been a major challenge for commercialization of stem cell technologies, rendering them inaccessible for a majority of applications.
To overcome this obstacle, researchers in the department of biochemical engineering at University College London (UCL) recently developed an automated stem cell culture system in a microplate format, offering higher consistency and reproducibility, better protection of cells from contamination, and improved operator safety. The new system also provides a valuable platform for fundamental studies of the culture microenvironment in stem cell biology.
The regenerative medicine bioprocessing program within the UCL department of biochemical engineering focuses on two areas: regenerative medicine translation and bioprocess engineering of stem cells. Both academic and commercial collaborations are essential in this research, which addresses the complete stem cell process from donor or patient biopsy through to clinical implantation into the patient.
The bioprocess engineering aspect of this work deals with the critical challenge of developing reliable processes for the preparation of homogenous populations of stem cells and their progeny. A project funded by the U.K.’s Technology Strategy Board investigates the production of pluripotent and differentiated stem cells in microplate formats, for applications such as compound library screening for drug discovery.
Limitations of Manual Cultivation
High variability and low consistency are major problems in manual stem cell culture processes, for both growth of stem cells and their differentiation into pre-defined cell types. Variations in environmental conditions during bioprocessing have the potential to significantly impact the outcome of stem cell cultures, making it difficult to reproduce experimental protocols and interpret the results obtained.
Many manual handling steps are needed to obtain the final cell population, requiring multiple passages, media exchanges, and cell transfers, each with the potential for contamination and propagation of errors.
Most significantly, it is practically impossible to control several key parameters during these manipulations—most notably temperature and CO2 concentration—as plates are moved from environmentally controlled incubators at 37ºC and 5% CO2, to a biological safety cabinet at room temperature (20–24ºC) and atmospheric CO2 levels (~0.04%), as illustrated in Figure 1.
As a consequence, rapid cooling and diffusion of CO2 out of the media occur, leading to fluctuations in the pH of the culture (Figure 2). Stem cells are extremely sensitive to such changes in pH, and this leads to poor reproducibility in manual culturing, representing a major obstacle to both furthering our understanding of stem cell biology and the commercialization of stem cell applications.