Overexpression of Matriptase‐1 Inhibitor HAI‐1 as an Effective Strategy to Reduce Proteolytic Clipping in Chinese Hamster Ovary Cells

Proteolytic degradation of recombinant proteins in Chinese hamster ovary (CHO) cells remains a major challenge in biopharmaceutical manufacturing, often reducing product yield and quality. Matriptase-1, a type II transmembrane serine protease, has been identified as a key contributor to unwanted proteolysis. This study investigates hepatocyte growth factor activator inhibitor-1 (HAI-1) overexpression as a strategy to mitigate matriptase-1-mediated degradation in CHO cell culture. Using an IL-12 IgG1 Fc fusion protein and a multi-specific antibody (M molecule) as model proteins, we employed genetic and biochemical approaches to assess the impact of Chinese hamster HAI-1 overexpression on protein quality and yield. Our results demonstrate that HAI-1 overexpression effectively inhibits matriptase-1 activity, achieving up to a 98% reduction in proteolytic clipping while maintaining cell growth, viability, and product quality. Compared to other protease control strategies, HAI-1 overexpression presents a practical and scalable solution that does not disrupt essential cellular functions. These findings establish HAI-1 as a key modulatory tool in CHO-based protein production, with implications for reducing proteolysis of therapeutic proteins and optimizing biopharmaceutical manufacturing processes.