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Transforming lentiviral vector analysis for cell and gene therapies 


Lentiviruses are key tools in the cell and gene therapy space, representing one of the most popular viral vector platforms. Accurate characterization of lentiviral vector (LVV) populations is essential throughout the production process – Key metrics such as sample purity, stability and physical titer are crucial checkpoints for ensuring quality and efficacy.  

Analyzing these metrics, however, presents significant challenges. Conventional vector characterization techniques have considerable limitations – cell-based analyses are time-consuming, requiring days for a result, while faster methods like nanoparticle tracking analysis (NTA) offer only limited data. A lack of efficient in-process tools creates substantial bottlenecks in the development of cell and gene therapies. 

Macro mass photometry is an innovative new approach that streamlines lentiviral vector analysis, offering rapid, accurate assessments that are critical for therapy development. Discover how our technology can help enable the development of more reliable and effective therapies in a fraction of the time. 

Macro mass photometry enables rapid characterization of lentivirus samples 

Introducing the KaritroMP, a state-of-the-art benchtop instrument that harnesses the power of macro mass photometry to rapidly characterize LVV samples. This breakthrough technology measures two critical parameters for each particle – contrast (a qualitative measure related to particle composition and mass) and size. Our multi-parameter approach allows for the precise differentiation of particles that may have the same size but differ in mass, offering a deeper insight into the composition and purity of viral vector samples. 

Key benefits of macro mass photometry:

  • Speed: Analyzes samples in minutes, dramatically accelerating process development 

  • Comprehensive assessment: Evaluates both purity and stability, prides valuable insights into particle populations, and reveals impurities 

  • Precision: Employs a single-particle technique, identifying distinct subpopulations within a sample 

  • Versatility: Suitable for use at every step of the process 

  • Cost efficiency: Detects process faults early and assesses sample quality rapidly, saving time and reducing costs 

  • Innovative approach: Enhances workflow efficiency with technology tailored for large viral vector analytics 

With the ability to perform rapid purity assessments, macro mass photometry is ideal for determining which samples are ready for further infectious titer analysis. By streamlining the vector characterization process, it not only saves time and money but also expedites the production of effective and safe cell and gene therapies. 

Macro mass photometry differentiates LVVs from other particles 

LVV samples are notoriously heterogeneous, often containing process- and product-related impurities that can significantly complicate their analysis during therapeutic development. Macro mass photometry tackles this challenge head-on. By measuring both contrast and size, the technology enables the definition of a specific “LVV region” corresponding to the contrast and size limits of LVV particles. 

Macro mass photometry histograms demonstrating the ability of macro mass photometry to quantify LVV populations in crude or heterogenous samples.

Figure 1. Macro mass photometry reveals LVV enrichment in purified vs. crude samples. The percentage of particles within the LVV region increased 10-fold after purification – a result consistent with the marked increase in functional titer reported by the samples’ manufacturer. In each panel, the percentage of particles with contrast and size within the LVV region is indicated. Samples were from Revvity Gene Delivery. 

The ability of macro mass photometry to analyze on a particle-by-particle basis is particularly advantageous for heterogeneous samples encountered during LVV production. This single-particle resolution ensures that even in diverse mixtures, LVVs can be accurately identified and quantified. 

Macro mass photometry LVV measurements correlate with titer  

Histogram showing strong correlation between physical titer, determined via PERT assay, and LVV region counts, determined via macro mass photometry

Figure 2. Macro mass photometry analysis using the KaritroMP correlates with physical titer. For 12 infectious, non-infectious and control samples, the percentage of particles within the LVV region in macro mass photometry analysis is plotted against physical titer (measured via PERT assay). The samples were provided by Prof. Dirk Lindemann, TU Dresden 

Correlation with Functional Titer

While macro mass photometry does not directly measure functional titer, tests on samples with known functional titers demonstrate a correlation between macro mass photometry counts in the defined LVV region and the functional titer. This suggests that, while it isn’t a direct substitute for functional titer measurement techniques, macro mass photometry provides valuable preliminary insights. 

Conventional methods for measuring functional titer are often slow and not applicable for in-process checks. In contrast, macro mass photometry offers a rapid, cost-effective alternative for reliable quality assessments. By leveraging macro mass photometry, researchers can quickly determine the viability of a sample before proceeding with more time-intensive and costly analyses, optimizing the development workflow and reducing resource expenditure. 

Macro mass photometry solutions for LVV analysis 

The new KaritroMP is a benchtop instrument that characterizes large viral vectors. Ideal for informing process development in preclinical settings and early drug development, it analyzes samples of adenovirus vectors (AdV) and lentivirus vectors (LVV) in just minutes. The instrument offers essential vector analysis capabilities, including the assessment of sample purity and stability:

  • Fast, simple, qualitative AdV and LVV analysis   

  • Differentiation of multiple populations, even those of the same size   

  • Evaluation of relative changes across samples, from crude to purified  

KaritroMP macro mass photometer

Testimonials from macro mass photometry users

" Data is terrific. I see its deployment for a more accurate measurement of physical titre: faster, less laborious that current methods, very informative, exciting new info."

Academic collaborator 

Additional resources

To learn more about how macro mass photometry could accelerate your LVV analysis 

Refeyn and Samux are registered trademarks of Refeyn Ltd. 

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