Rational scale-up of a baculovirus-insect cell batch process based on medium nutritional depth.

Area of Science:

• Biotechnology and Bioprocessing
• Recombinant Protein Production
• Enzyme Replacement Therapy

Background:

• Gaucher disease is a genetic disorder caused by a deficiency in the lysosomal enzyme glucocerebrosidase.
• Current therapies may involve enzyme replacement, necessitating efficient production methods.
• Insect cell culture systems offer a scalable platform for recombinant protein production.

Purpose of the Study:

• To develop and validate a serum-free cell culture process for producing human glucocerebrosidase using Trichoplusia ni insect cells.
• To establish a semi-empirical model for optimizing scale-up parameters, including host cell density, multiplicity of infection (MOI), and harvest time.
• To enable efficient and cost-effective production of glucocerebrosidase for potential therapeutic applications.

Main Methods:

• Utilized a recombinant baculovirus (AcNPV) expression vector to infect Trichoplusia ni cells in a serum-free medium.
• Developed a semi-empirical model based on nutritional capacity limits of the medium, determined by uninfected cell growth.
• Conducted pilot scale-up from 25-mL shaker flasks to 25-L stirred bioreactors, validating model predictions empirically.

Main Results:

• The model identified optimal infection parameters: host cell density of 1.5-2.0 x 10^6 cells/mL and MOI of 0.09-0.3 for a 4-day batch process.
• Empirical validation confirmed these parameters yield maximum batch product, achieving high infected cell densities (>4 x 10^6 cells/mL).
• Bioreactor scale-up achieved equivalent protein production in 4 days versus 5 days in shaker flasks, potentially due to improved environmental control.

Conclusions:

• The developed serum-free process and predictive model enable rational scale-up of glucocerebrosidase production in Trichoplusia ni cells.
• The process successfully produced secreted glucocerebrosidase, a potential treatment for Gaucher disease.
• Further optimization may involve managing inhibitory metabolites (ammonia, lactate) produced by T. ni cells for high-density cultures and fed-batch strategies.