Mammalian cells are frequently
selected as expression systems for protein biopharmaceuticals because of their
ability to produce proteins with ‘human-like’ post-translational modifications.
The structure of these products can, to a large extent, be controlled by
ensuring that the genetic sequence encoding the biopharmaceutical has been
inserted stably into the host cell genome. However, the effective control of post-translational
modifications such as glycosylation is much more of a challenge requiring an
understanding of the cellular mechanisms that lead to different profiles along
with how they can be manipulated or at least controlled by bioprocessing
parameters. Yet the glycosylation profile is an important characteristic of a
biopharmaceutical because of its potential to effect the biological properties
of the drug such as pharmacokinetics, bioactivity and antigenicity amongst
others.
Cellular Factors Impact
Glycosylation
In an article entitled “Optimisationof the cellular metabolism of glycosylation for recombinant proteins producedby mammalian cell systems” (Cytotechnology, 2006, 50:57-76), Mike Butler from
the University of Manitoba describes the following factors that impact
glycosylation within the environment of the cell:
·
3D protein structure
·
Enzyme repertoire of the host cell
·
Transit time through Golgi apparatus
·
Availability of intracellular sugar-nucleotide
donors
7 Bioprocess Parameters For
Controlling Biopharmaceutical Glycosylation
Research described in Bulter’s
paper has shown that engineers can utilize a range of bioprocessing parameters to
effect these intracellular factors and control glycosylation profiles such as:
2. Concentration of Ammonia
3. pH
4. Dissolved oxygen levels
5. Cell line selection
6. Cell growth rates
7. Protein production rate
Modelling Glycosylation
Patterns
The relationship between
processing parameters and recombinant protein glycosylation patterns can be
determined experimentally using scale-down models and multifactorial
experimental designs. However, development costs and time would be reduced
still further if models capable of predicting glycol-profiles could be
developed and is now a subject of investigation by researchers around the
world.
Join me at #BPIconf
Contact me at nick.hutchinson@parker.com
Dr Nick Hutchinson has a Masters and Doctorate in
Biochemical Engineering from University College London, UK where he focused on
laboratory tools for rapid bioprocess development and characterization. He then
worked at Lonza Biologics in an R&D function investigating novel methods
for large-scale antibody purification before moving to an operational role
scaling-up and transferring manufacturing processes between Lonza sites in the
UK, Spain and USA. Nick now works in Market Development at Parker domnick
hunter where his focus is in bringing Parker's strengths in Motion &
Control to Bioprocessing. This will enable customers to improve the quality and
deliverability of existing and future biopharmaceuticals.
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