Antibody Discovery With MicroBubble Arrays

Nidus’s founders have developed our MBA™ technology for cell growth and manipulation applications, including in “biochip” applications, which is a market expected to grow to $18B by 2020.

One particularly powerful application of our technology is the growth and high-throughput screening of antibody-producing cells using our arrays.  In this type of application we plate out dispersed cells at low concentration over a microbubble array; cells settle by gravity deposition, and those cells settling in microbubbles have an increased probability of growing.  The micrograph shows the feasibility of this approach for growing few/single cells, specifically a detail of 12 microbubbles, each with from 0-3 growing cells. For more details on this data see Jones MC, Kobie JJ, DeLouise LA. “Characterization of cell seeding and specific capture of B cells in microbubble well arrays.” Biomedical microdevices. 2013 Jun; 15(3):453-63.

For some applications the presence or absence of growing cells is a productive endpoint in itself; however, a particular target application for our technology is a system for screening a population of growing cells for those cells producing an antibody of interest.

Our founders have developed a number of high-throughput screening methods for this secreted-product endpoint. The illustration shows one such method where secreted anti-tetanus toxin immunoglobulins from SA13 hybridoma cells were detected by a fluor-based reporter –see the “Bobo” publication: Bobo B, Phelan D, Rebhahn J, Piepenbrink MS, Zheng B, Mosmann TR, Kobie JJ, DeLouise LA. “Microbubble array diffusion assay for the detection of cell secreted factors.” Lab on a chip. 2014 Sep 21; 14(18):3640-50. Epub 2014 Jul 31.

The figure below from this publication shows data obtained using this experimental design, the  MBA™ is imaged using fluorescent (A) as well as bright-field imaging (B) of the same section of the array; the white arrows in (B) indicate microbubble wells with more than 8 cells.

These data show not only the ability to detect IgG secretion from SA13 cells in individual microbubble wells, but also the ability to detect different levels of IgG production from these cells as a function of the cells in any particular well, i.e., by the differing brightnesses of fluorescent signals in different wells in panel (A).  This variation is shown graphically in panel (C).  In other experiments using this same hybridoma cell line, our founders have demonstrated that cells may be recovered  from individual wells and further characterized by, e.g, PCR amplification and gel analysis.

Validation of MBA™s For Antibody Discovery From Primary B Cells

The above data relate to a hybridoma cell line; however, we have also validated the MBA™ technology for primary B cells, including human primary B cells; in this regard, primary B cells are the cells harvested in order to obtain antibodies for use as biological drugs.  Thus the fluorescence micrograph below from the same Bobo publication cited above shows that IgG secretion (white rings) can be detected from human primary B cells cultured in an MBA™ for 48 hours:

The micrograph to the left shows a detail from the array reproduced above, and specifically shows three microbubble wells with live human B cells cells labeled in green and secreted IgG in red.  As the micrograph shows, all three wells have live cells, however only the cells in the rightmost well are producing IgG.

These data validate the use of the MBA™ system for high-throughput screening of primary B cells for research and particularly for new antibody drug discovery.  Nidus has built a number of collaborations/partnerships with groups actively engaged in this technology area.

All figures reproduced by permission.