An Integrated Production Process for Human Growth Hormone

Abstract

A combination of perfusion culture and the expanded bed technology has been used with a CHO cell line to produce human growth hormone.

For the hGH production a perfusion process was established in a 2 litre lab-scale bioreactor with an inclined settler for cell retention. The cell concentration was controlled by an Oxystat to maintain steady state-like conditions. Physical culture parameters like temperature, pH and stirrer speed were investigated in order to optimize culture conditions for productivity and long term stability. A pH shift to 6.8 combined with a temperature reduction to 33°C resulted in low cell specific dilution rates of 0.05 nL/cell^*d. At the same time volumetric productivities above 500 mg/L^*d were achieved.

A salt tolerant ion exchanger was used for direct product capture from the perfusion supernatant. The second purification step was a hydrophobic interaction chromatography. It was shown that an optimized ammonium sulphate concentration resulted in a yield of about 80%. For elution and virus inactivation 2-propanol was used. Concentration and solvent elimination was conducted by anion exchange chromatography.

There was no formation or accumulation of dimers or desamidated human growth hormone, as shown by size exclusion chromatography and RP-HPLC. An in-vitro proliferation assay and animal trials in rats demonstrated the biological activity of the purified product.