Quasi-perfusion studies for intensified lentiviral vector production using a continuous stable producer cell line.

Quasi-perfusion culture was employed to intensify lentiviral vector (LV) manufacturing using a continuous stable producer cell line in an 8-day process. Initial studies aimed to identify a scalable seeding density, with 3, 4, and 5 × 10 cells cm providing similar specific productivities of infectious LV. Seeding at 3 × 10 cells cm was selected, and the quasi-perfusion was modulated to minimize inhibitory metabolite accumulation and vector exposure at 37°C.

Continuous manufacturing of lentiviral vectors using a stable producer cell line in a fixed-bed bioreactor.

Continuous manufacturing of lentiviral vectors (LVs) using stable producer cell lines could extend production periods, improve batch-to-batch reproducibility, and eliminate costly plasmid DNA and transfection reagents. A continuous process was established by expanding cells constitutively expressing third-generation LVs in the iCELLis Nano fixed-bed bioreactor. Fixed-bed bioreactors provide scalable expansion of adherent cells and enable a straightforward transition from traditional surface-based culture vessels.

Liposome Sterile Filtration Characterization via X-ray Computed Tomography and Confocal Microscopy.

Two high resolution, 3D imaging techniques were applied to visualize and characterize sterilizing grade dual-layer filtration of liposomes, enabling membrane structure to be related with function and performance. Two polyethersulfone membranes with nominal retention ratings of 650 nm and 200 nm were used to filter liposomes of an average diameter of 143 nm and a polydispersity index of 0.1.

Optimizing the Filtration of Liposomes Using Sterilizing-Grade Filters.

Liposomes are increasingly being investigated and implemented as injectable drug delivery systems. The preferred method for sterilizing injectable drug formulations using liposomes is to use filtration. However, because of the size of liposomes and their physicochemical properties, this can be challenging with sterilizing-grade filters rated at 0.

Internal virus polarization model for virus retention by the Ultipor(®) VF Grade DV20 membrane.

Several recent studies have reported a decline in virus retention during virus challenge filtration experiments, although the mechanism(s) governing this phenomenon for different filters remains uncertain. Experiments were performed to evaluate the retention of PP7 and PR772 bacteriophage through Ultipor VF Grade DV20 virus filters during constant pressure filtration. While the larger PR772 phage was fully retained under all conditions, a 2-log decline in retention of the small PP7 phage was observed at high throughputs, even under conditions where there was no decline in filtrate flux.