Project summary: High-throughput Single Cell Screening Using a MEMS Assay

Within this project we want to take the first steps towards an automated system for high-throughput single cell based screening in the production of novel biopharmaceuticals using a new MEMS array technology which allows for single cell read-out.

The current sales of biotherapeutics in the biopharmaceutical industry is close to US$125 billion. The amount of new cell line development projects for drug production purposes is still growing rapidly mainly due to the expiration of blockbuster biologics which has spurred the emergence of biosimilars. Mammalian cells have been utilized for a long time in the production of biopharmaceuticals. Currently cell handling is executed at the colony level (single-colony-based-breeding). However, these colonies are highly heterogeneous in nature due to the gene amplification process and random gene integration. As a result, production rates amongst different cells in a colony varies greatly. This implies that large numbers of clones have to be screened to identify the rare stable high producer cell clones. Consequently, the current cell line development processes are extremely time, labour and capital intensive.

High-producing cell lines could be established much more effectively by sorting single cells (as opposed to colonies), with high and stable expression rates, early in the production process. Microwell array technology, whereby each microwell occupies a single cell, has been suggested as a means for high-throughput screening of large numbers of individual cells. The bottleneck which currently hampers microwell array technology from entering the market successfully is the lack of an efficient and sensitive single cell read-out system.

In the current project a MEMS microarray will be developed containing a read-out pore (or read-out pores) in the bottom of each well in the array. These pores will allow stamping of products (such as antibodies) secreted by individual cells on a substrate such as paper, pvdf, other. Subsequently, read-out will be performed using for example ELISA technology and/or fluorescently labelled antibodies.

The major advantage of this approach is that the readout system does not interfere in any way with the cells in the wells of the array. Moreover, due to the sensitivity of the immunological read-out it is expected to be fast. Other advantages include that the read-out methodology is highly selective (allowing discrimination between antibody isotypes and/or subclasses), high throughput, quantitative, cheap, simple and compatible with current workflows in the field.