Using Nanoscale Bioreactors to Charactarize Sub-Populations of Cho Clones and Screen Transfected Pools

Traditional methodologies to quantify growth and production rates for antibody-expressing CHO clones involve repeatedly sampling aliquots and supernatants from well plates that have been seeded with single cells. The number of clones studied is often limited by cloning efficiencies (typically 5-50%) and the inability to handle large numbers of well plates. Measurement cadence is limited by the growth rates of cells and the number of cells required to perform each assay. These factors limit the practical throughput of screening clones to 100s over the course of 2-4 weeks. Furthermore, measurements of clone behavior at small scales often correlate poorly with larger fermenter reactors due to significantly different culture environments.

Bruker Cellular Analysis has developed a platform that uses disposable nanofluidic chips to screen 5000 clones in individual nanoscale bioreactors automatically within 5 days. Individual cells are placed in separate chambers (NanoPens) using light-induced dielectrophoresis. Clones are continuously perfused in tightly-controlled reactor-relevant microenvironments leading to 60-80%cloning efficiency. Clones are imaged and analyzed with a deep learning algorithm to provide very high-fidelity morphology and growth rate characteristics. Antibody production is measured with a quantitative secretion assay using fluorescently-tagged small molecules, independently measuring all clones simultaneously. Selected clones can be recovered from the chip for scale up.

In collaboration with Daiichi Sankyo (DS), two applications were explored. First, a head-to-head comparison of DS’s current clone screening methodology and the Beacon workflow was performed on a transfected pool. Second, previously characterized clones were sub-cloned on the Beacon and the behavior of each clone was measured over the course of 8 weeks. Analysis demonstrated the ability to measure and predict the stability of each clonal cell line.