We have further developed and optimized the commercial level instrumentation of an automated microfluidic cell culture system, and have deployed a prototype system to a collaborator site for testing. We have demonstrated that we can change cells into different types of neurons using only chemically-defined factors – i.e. only reagents that could be used in a clinical protocol. We have shown that we can do this in several different ways (either with synthetic nucleic acids (RNA) or small molecules like drugs). Furthermore, we have shown that we can get cells out of the system and measure the gene expression of single cells individually.
Finding the right culture conditions to grow cells and transform them into desired types of cells is central to stem cell research and cell-based therapies. It is also very challenging: experiments in traditional culture systems are often labor intensive and difficult to reproduce due to the need to screen many factors involved in the cellular processes. Using advanced microfluidic technologies at Fluidigm, we have developed a prototype automated instrument that can culture cells on microfluidic chips for more than 2 weeks and automatically dose different cells with different permutations and combinations of multiple factors. In the last year, we have further optimized key components of the system to improve the thermal, pressure and fluidic delivery performance. We have also redesigned the environmental control system so that it can be an add-on module to a commercial instrument (the C1 Single Cell Auto Prep System), which will make it easier for researchers to do these types of cell culture condition screening experiments. Two new versions of the microfluidic chips have been designed and tested to offer more flexibility of cell dosing scheme and longer duration of unattended experiments. Cells can be stained with fluorescently-labeled cell-type specific markers on chip and images scanned with an automated microscope. We have also optimized a workflow to export live cells from the culture chip and analyze the gene expression profiles of single cells which may shed lights on cell-cell variability within a cell population.
A desired target cell type may be derived in vitro by either direct conversion from another committed cell type or differentiation from stem cells or progenitor cells. Direct conversion is usually much faster and more efficient, but stem cells, especially induced pluripotent stem cells, are more versatile and proliferative and easier to generate millions of cells. We have demonstrated both methods on chip by converting human fibroblasts to neurons with combinations of micro RNAs and messenger RNAs, and by differentiating human induced pluripotent stem cells into pain receptor neurons with small molecules. The results were in agreement with published reports, and were confirmed in large well-dish culture format. We have established chemically-defined conditions for both protocols and are currently optimizing the protocols for higher induction efficiency and better cell health.
Due to its precise control and easy set-up of multifactorial screening experiments, we believe this automated system will be a valuable tool for the stem cell and the general cell biology research community, and we plan to continue our efforts in optimizing the instrumentation and exploring the biological applications.