Selection of high yield recombinant human bone morphogenetic protein 2 (rhBMP2) cell pool based on different screening markers used for CHO cell line development

The Chinese hamster ovary (CHO) cell line is a typical host for the production of therapeutic proteins, which can be genetically manipulated to express glycoproteins with correct assembly. Recombinant human bone morphogenetic protein 2 (rhBMP2) is an osteogenic therapeutic option that is often produced in CHO cells. In this work, two common host strains, CHO-K1 and CHO-DG44, were used for the production of rhBMP2. CHO-K1 cells were cultured and transfected with the EGFP/NeoR and rhBMP2/NeoR expression vectors via the CRISPR/Cas9 method, which targets the Hipp11 locus of the host genome. Similarly, CHO-DG44 cells were cultured and transfected with the rhBMP2/DHFR vector. Recombinant rhBMP2 cells were screened using the neomycin resistance gene in CHO-K1 cells and the dhfr gene in CHO-DG44 cells. The surviving recombinant cells were expanded, and then expression of rhBMP2 were analyzed by ELISA. The level of rhBMP2 expression in the recombinant cell pools revealed the importance of efficiency of the screening strategy and genome editing method. In conclusion, the use of an appropriate strain of host cell and efficiency of selective markers can affect the recombinant protein expression that is important for the industrial pharmaceutical production.