Jy. Chung et al., Morphological selection of parental Chinese hamster ovary cell clones exhibiting high-level expression of recombinant protein, BIOTECHNIQU, 29(4), 2000, pp. 768
To facilitate the establishment of recombinant Chinese hamster ovary (rCHO)
cell lines with dihydrofolate reductase (dhfr)mediated gene amplification,
a primary selection method based on morphology of parental CHO clones has
been developed Morphology of parental clones that were made by transfecting
various plasmids encoding thrombopoietin (TPO) and its analogs and humaniz
ed antibodies into dhfr-deficient (dhfr(-)) CHO cells was not uniform. Morp
hology of many parental clones exhibiting high-level expression of the intr
oduced gene was similar to that of nontransfected dhfr- CHO cells. On the o
ther hand, most parental clones with low-level expression experienced notic
eable morphological changes such as bipolar fibroblast-like morphology. In
case of selection of parental clones with TPO expression level higher than
200 ng/mL, morphological selection improved selection efficiency by 3.5-fol
d compared with random selection. Furthermore, when subjected to methotrexa
te for gene amplification, parental clones that were selected based on morp
hology elevated the expression level as much as those that were selected ra
ndomly. Taken together morphological selection of parental clones can facil
itate the establishment of rCHO cell lines expressing recombinant proteins.