Researchers at the University of Applied Sciences Jena have discovered a novel method to improve the small-scale cultivation of Spodoptera frugiperda 9 (Sf9) cells by silanizing glassware. This approach could significantly advance insect cell culture practices.
The cultivation of insect cells presents several challenges, particularly concerning the uncontrolled adhesion of cells to vessel surfaces, resulting in lower cell viability and reproduction of experiments. Traditional glass vessels, rich with hydroxyl groups, create hydrophilic surfaces where media and cells adhere uncontrollably. This phenomenon leads to visible cell rims forming inside the vessel walls, diminishing the overall cell count and impacting experimental consistency.
To counteract these issues, the researchers explored silanization—a process altering the surfaces of glass containers by converting Si–OH bonds to Si–O–Si bonds, yielding more hydrophobic and inert surfaces. By applying Sigmacote, they aimed to create glassware conducive to optimal insect cell growth and performance.
During the experimental phase, the study compared the growth parameters of Sf9 cells cultivated within silanized versus non-silanized glass vessels of varying sizes—10 ml culture tubes, 50 ml flasks, and 250 ml flasks.
Remarkably, the results showed significant improvements when using smaller vessels. According to the researchers, "Silanizing glassware reduced adhesion of cells and cell debris to the vessel walls visible as rim formation especially at the beginning of cultivation." This reduced cell adhesion led to increased living cell counts, improved viability, and even enhanced reproducibility of experiments.
For example, the growth curves indicated no lag phase for Sf9 cells grown in silanized 10 ml culture tubes, significantly increasing the maximum cell density and cell viability compared to their non-silanized counterparts. Meanwhile, the findings also highlighted improvements for 50 ml flasks, demonstrating decreased lag time by 24 hours and improved viability at the start of the cultivation period.
On the other hand, no similar benefits were observed when silanizing 250 ml culture flasks, where cell growth remained comparable whether treated or untreated. Researchers suggest this may be due to the vessel size ratio to the volume of the cell suspension. Nonetheless, the potential advantages of silanization for larger vessels include reduced cleaning efforts and fewer organic materials clinging to vessel surfaces.
This approach shows promise not only for minimizing costs associated with the use of single-use plastic consumables but also for making experiments more reliable by creating reproducible environments for cell growth. "While previous research assumed... our data indicate... it is most useful when working with Sf9 cells in small culture glass vessels," the authors assert, confirming the viability of this innovation.
With this new methodology, researchers can improve the routine cultivation of Sf9 cells, which are important for biomanufacturing processes such as producing viral vaccines and gene therapy vectors. Overall, the study paves the way for greater efficiency and success potential within insect cell culture environments.
Further studies could explore the effects of silanization across different cell types and scales, providing richer insights and applications of this technique.