Since launch of the first therapeutic monoclonal antibody in 1986, antibody-based biologics have become a major class of modern medicine. With the market predicting that there will be approximately 70 new monoclonal antibody based therapeutics available by 2020 there is growing pressure to reduce the time it takes for discovery and development, meaning a need for more efficient screening and more precise methods for monoclonal antibody identification and generation (Ecker, et al., 2015). Current methods for antibody discovery are well established and have proven success rates with the majority of FDA-approved therapeutic antibodies derived from hybridoma populations and the humanization of rodent antibodies (Lu, et al., 2012).
However, the semi-automated technologies currently used to develop monoclonal antibodies are time-consuming, resource-intensive and consequently result in an inefficient workflow due to their low screening throughput, which hinders the ability to effectively deep mine B cell repertoires. Consequently, there is an urgent need for strategies and technologies to enable the screening of the full range of B cells along with their secreted antibodies.
The emergence of microfluidic-based picodroplet technology platforms, like Cyto-Mine®, offers a solution that enables the rapid screening of millions of B cells and their secreted antibodies.
The core technology behind picodroplet microfluidics is based on the encapsulation of a single cell within a picolitre-volume aqueous droplet or ‘picodroplet’ which provides a unique microenvironment for each cell, where secreted proteins and biomolecules can be trapped and assayed. This approach is particularly rapid, yet gentle, and allows single B cells secreting antibodies to be isolated from large heterogeneous populations based on the antigen-specificity of secreted antibodies.
One benefit of conducting assays in picodroplets is that picodroplets are approximately 5-6 orders of magnitude smaller than volumes in conventional assays, consequently the concentration of secreted antibodies from a single cell in a picodroplet is approximately 5-6 orders of magnitude higher resulting in a highly concentrated assay that uses a fraction of the quantity of reagents overall increasing efficiency and dramatically shorten assay time.
One in a Million
In addition to single cell encapsulation, multiple cells can be captured within a picodroplet which provides the advantage of being able to screen tens of millions of cells in one run. By screening picodroplets with multiple cells an initial assay (to identify cells secreting antibodies) can be carried out before a secondary screen where the ‘hit’ cells are re-encapsulated and assayed for antigen specificity. This type of two-step screening with Cyto-Mine® offers the ability to find an antigen-specific population of B cells that can have “hit cells” occurring at rates as rare as 0.0005%.
Microfluidic-based picodroplet technology provides a major advantage over the resource intensive process of hybridoma generation as very few B cells survive the fusion process with myeloma cells. Using a fully integrated and automated platform allows the direct screening of B cells, not impacting their viability, not requiring cell fusion and increasing the likelihood of finding that valuable cell.
One final benefit is the cell-friendly environment of the picodroplet. When a picodroplet forms it encapsulates a single cell along with culture medium which provides a protective ‘capsule’ that supports cell integrity as they flow through the microfluidic channels. The picodroplet protects cells against sheer stress (like a cushion) and the bio-compatible surfactants used in picodroplet formation promote high levels of gas exchange and oxygen concentration.
A Revolutionary Platform for Antibody Discovery
Combining B cell isolation, screening, and antigen-specific assays into a fully automated workflow, improves the screening efficiency and reduces costs of assay reagents.
This powerful technology is poised to revolutionize antibody discovery by addressing the key needs of reduced costs, higher throughput and greater sensitivity, offering solutions to help transform antibody discovery and the development of novel biotherapeutics.
Ecker, D., Jones, S. D. & Levine, H., 2015. The therapeutic monoclonal antibody market. BioProcess Technology Consultants, Inc., pp. 9-14.
Lu, Z.-J.et al., 2012. Frontier of therapeutic antibody discovery. World Journal of Biological Chemistry, pp. 187-196.