Exploring the diversity and productivity of clonal Chinese hamster ovary host cell lines derived from a non-clonal population

Abstract

Abstract for a PhD in Biotechnology thesis submitted in September 2015 at the University of Manchester by Andrew Richard Jeavons titled "Exploring the diversity and productivity of clonal Chinese hamster ovary host cell lines derived from a non-clonal population"Chinese hamster ovary (CHO) cell lines are the most frequently used mammalian host for commercial production of recombinant protein-based biopharmaceuticals. Heterogeneity and phenotypic drift in CHO populations is well established, thus production cell lines must be clonally derived to help ensure product purity and homogeneity. A vast range of engineering strategies has been employed to improve the bioprocessing capabilities of CHO cell lines and decrease production costs, although these strategies have yielded mixed results. The use of clonally derived host CHO cell lines, may allow exploitation of the genetic and phenotypic variability in parental populations for the discovery of new hosts with desirable, heritable characteristics. Furthermore, in-depth characterisation of phenotypic diversity may assist in the development of tools and molecular markers to rapidly identify a desirable cell line.A panel of clonally derived host CHO cell lines and the non-clonal parental population were investigated to determine their phenotypic variability, and their ability to produce transfectants with predictable characteristics. Significant differences were identified in the growth profiles and proliferative capacity of the host cell lines, in addition to their nutrient utilisation, endogenous protein expression and mitochondrial membrane potential. Transfection of the host cell lines did not suggest that the use of clonal host cell lines produces transfectants with less phenotypic variability than transfectants derived from a non-clonal population. However, transfectant population averages suggested that a 'toolbox' of host cell lines could be developed, in which specific hosts may improve the probability of isolating transfectants with a desired phenotype.Rhodamine-123 (Rh-123) staining and flow cytometric analysis of host cell lines identified interclonal variability in mitochondrial membrane potential. Extending this approach to transfectants suggested this is a heritable property of CHO cell lines, which correlates with growth rate, and the glucose and lactate utilisation of the host cell line. Rh-123 could serve as a tool for rapid screening of prospective host cell lines, without the need for scale-up and batch culture. Furthermore, gas chromatography-mass spectrometry (GC-MS) metabolomic analysis of transfectants, with high productivity and low productivity, identified novel metabolites which may be linked to the productivity phenotype.This study has shown that the diversity of CHO populations can be utilised to isolate novel host cell lines with different phenotypes that are desirable for biopharmaceutical production. This approach has the potential to increase production yields and decrease biopharmaceutical production costs without the need for cell line engineering.

Date of Award	1 Aug 2016
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Mark Ashe (Supervisor) & Alan Dickson (Supervisor)