By Gail Dutton

Raman spectroscopy will likely become a key technology for monitoring upstream and downstream processing as well as manufacturing of cell and gene therapies (CGT) in the coming years. New applications are providing information online, non-invasively, in real time, thus minimizing laborious offline analyses.

Writing in a recent paper, scientists at Sartorius Stedim sites throughout Europe and North America identified several new applications in upstream and downstream bioprocesses, as well as in cell and gene biomanufacturing.

Applying Raman spectroscopy variants, such as surface-enhanced Raman spectroscopy to analyze low levels of analytes and large particles, time-gated Raman to reduce background fluorescence, or Raman microspectroscopy to provide chemical identities of cells or organelles without fixation or labeling, are just a few possibilities.

Upstream

New upstream applications include monitoring amino acids and antibody N-glycosylation in high-density cell perfusion cultures. By inserting probes directly into the bioreactors, scientists developed predictive models for cell cultures, including such attributes as cell density, lactate, ammonium and amino acid concentrations. Analysis enabled the product’s glycosylation pattern to be predicted in real time in high-density cell perfusion cultures.

Single-use spectral ports support use of commercial Raman sensors while maintaining a sterile barrier between the probe and the process fluid. This has been used in cell-free harvesting in a perfusion culture and to transfer process analytical technology (PAT) models from mini bioreactors to large-scale, stirred-tank bioreactors.

Downstream

Downstream applications, the paper notes, include:

  • “Combining mechanistic modeling and Raman spectroscopy to monitor monoclonal antibody (mAb) breakthrough curves in chromatographic operations with lower titer harvest.
  • “Protein characterization of therapeutic mAb IgG1 formulations during freezing and thawing.”
  • “Monitoring product quality attributes in mAb therapeutics using multi-attribute Raman spectroscopy.”

Therapeutic protein manufacturing

“Raman spectroscopy is well-established in therapeutic protein manufacturing, and now also is emerging in the viral and cell therapy field. It provides simultaneous, real-time data on a wide array of process parameters and even product quality attributes,” Gerben Zijlstra, PhD, process technology manager, and one of the paper’s authors, tells GEN. “This enables enhanced process understanding and advanced real-time process control, thus reducing manufacturing costs and risks.”

Potential applications include:

  • Measuring vector titer to support unit-specific performance.
  • Distinguishing among immune cell types.
  • Identifying active and inactive immune cells.
  • Diagnosing immune cell diseases.
  • Identifying differentiation and reprogramming of single cells using biomarkers.

These new applications are fairly novel in cell and gene therapy development, he points out. “Therefore,” the authors predict, “we will likely still need to wait a few years before seeing the impact of Raman spectroscopy to CGT manufacturing.”

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