An LDHa single allele CHO cell mutant exhibits altered metabolic state and enhanced culture performance

BACKGROUND: Reducing lactate production in animal cell cultures has been reported to improve cell culture performance and productivity of recombinant protein. A novel genome editing tool, CRISPR/Cas, has been used widely to induce double-strand breaks in the genome and introduce targeted mutations efficiently. RESULTS: In the present work, we used a publicly available human-codon optimized CRISPR/Cas system to introduce mutations in one of the LDHa gene copies to obtain an LDHa single-allele knockout Chinese hamster ovary (CHO) cell clone to analyze its effect over cell metabolism. Fed-batch cultures were conducted in order to evaluate the culture performance of mutant cells. Results show that cell growth was reduced and metabolism was modified by the LDHa single-allele knockout, whereas specific protein rate and volumetric production were greatly enhanced. Additionally, the first in-depth analysis of the metabolic effects of LDHa single allele knockout is presented. CONCLUSION: By using CRISPR/Cas we were able to knock down LDHa, showing improved culture productivity. Metabolic flux analysis revealed higher fluxes in the TCA cycle in the mutant cell than in the parental cell, indicating that LDHa mutant cells have an enhanced energy metabolism, which can be attributed mainly to a higher catabolism of amino acids.