Scientific Poster
MaxCyte® Scalable Electroporation: A Universal Cell Engineering Platform for Development of Cell-Based Medicines from R&D to Clinic
Abstract
Most cell-based therapeutic modalities, whether using viral vectors, immune cell engineering or in situ gene editing, share the need for some type of cell engineering. MaxCyte developed a non-viral, electroporation technology with the performance, flexibility, safety and scalability to aid cell therapy from development through manufacturing. In this poster we present the capabilities of MaxCyte scalable electroporation, a cGMP-compliant platform, with CE-marked instruments and an FDA Master file. Summarized are data for high-performance electroporation of a variety of common therapeutic cell types including adherent and suspension cell lines and primary cells. A breadth of real-world applications are highlighted, including lentivirus and adeno-associated virus (AAV) production, engineering of primary T cells for the expression of an anti-mesothelin CAR molecules, and CRISPR-Cas9 editing of stem cells. These data illustrate the scalability and consistency of MaxCyte electroporation enabling cell engineering from early R&D to patient dosing of cell-based therapeutics.
MaxCyte Transient Transfection Platform
The MaxCyte STx, MaxCyte VLX, and MaxCyte GT® transient transfection Systems use fully scalable flow electroporation for rapid, highly efficient transfection.
MaxCyte GTx®
Up to 2E11 Cells in <30 min Optimized for clinical use
MaxCyte STx®
5E5 Cells in Seconds Up to 2E10 Cells in <30 min
MaxCyte VLX®
Up to 2E11 Cells in <30 min
Viral Vector Production: Lentivirus & AAV
MaxCyte STx to VLX Instrument Scale-up
4 Plasmid Lentiviral System Production in Suspension Cells
Figure 1: Scale-up of Lentiviral Vectors from Small-Scale to Large-Scale Production Using the MaxCyte Platform. Suspension-adapted HEK293FT cells were suspended in MaxCyte electroporation (EP) buffer, 1E8 cells/mL. Cells were added to a mixture of plasmids encoding lentiviral components (0.4 ug DNA/1E6 cells) and transferred to sterile OC-400, CL-2 and VLXD processing assemblies for either static or flow electroporation using the STx® instrument. (OC-400 = static EP; CL-2 and VLXD = flow EP). Lentiviral titers were measured after 24-48 hours in culture. Normalized titers reveal the seamless scalability of the MaxCyte process.
Consistent Large-Scale Lentivirus Manufacturing
Suspension Cells Facilitate Scalability of Vector Production
| Production Number | Volume (ml) | Total Cells | Cumulative Titer (IU/ml) | Productivity (IU/Cell) | IU/ng of p24 |
|---|---|---|---|---|---|
| 1 | 2300 | 6.0E9 | 2.2E11 | 37 | 1.3E5 |
| 2 | 2300 | 4.8E9 | 2.0E11 | 42 | 1.4E5 |
| 3 | 2100 | 7.4E9 | 2.7E11 | 36 | 1.7E5 |
Table 1: Large-Scale Lentiviral Vector Production. Suspension-adapted HEK293FT cells were harvested, resuspended (1E8 cells/ mL), and co-transfected with 4 lentiviral plasmids by flow electroporation with the CL-2 processing assembly. Cells were cultured post EP in 10 L Cellbags in a Wave BioreactorTM in a final volume of 2.1-2.3 Liters. 48 hours post EP media was collected and both infectious particles and p24 concentrations measured. Results for 3 independent manufacturing runs are shown. These data demonstrate the reproducibility of MaxCyte flow electroporation enabling large-scale, quality lentivirus production. For full methods, see Hum Gene Ther. 2012 Feb;23(2):243-9.
High Titer AAV Production in HEK Cells
3 Plasmid Co-Transfection Yields High Efficiency & Titers
Figure 2: Production of AAV in HEK Cells. A) Adherent HEK cells were processed via static electroporation using the MaxCyte STx instrument to transfect 3 plasmids encoding AAV vector components and a GFP transgene. B) Nearly 100% of transfected cells exhibited transgene expression 48 hours post EP. C) High AAV expression was detected in cell pellets via qRT-PCR analysis.
T Cell Engineering: mRNA CAR
Development of an α-mesothelin CAR mRNA T Cell for Solid Tumors
Multiple Injections of Electroporated T Cells Expressing CAR Mediate Tumor Regression
Figure 3: Sustained CAR Expression and Regression of Tumors in RNA CAR T Cell-Treated Mice. A) Stimulated T cells were electroporated with clinical-grade, in vitro transcribed RNA (10 ug RNA/100 uL cells) encoding antimesothelin CAR including both the CD3-ζ and 4-1BB costimulatory domains using the MaxCyte GT and transgene expression analyzed daily via FACS. Electroporated cells expressed the transgene for up to 7 days post transfection.
Figure 4: Regression of Tumors in Mice Treated with RNA CAR T Cells. A) Flank tumors were established by M108 injection (s.c.) in NOD/scid/γc(−/−) (NSG) mice (n=6). 66 days after tumor inoculation, mice were randomized to equalize tumor burden and treated with meso-CAR RNA-electroporated T cells. T cells (1E7) were injected intratumorally using the same healthy donor every 4 days for a total of 4 injections; mice treated with saline as controls (n=3); tumor size measured weekly. Adoptive transfer of mesothelin-targeted CAR T cells via subcutaneous injection was safe without overt evidence of off-tumor, on-target toxicity against normal tissues. Additionally, in mice with established mesothelin-positive tumors, meso-CAR T RNA-electroporated T cells reduced tumor size, whereas progressive tumor growth was observed in the control group. B) Tumors were established in NSG mice (n=6 per group) by intraperitoneal injection with 8x10E6 M108-Luc cells. Beginning on day 58, RNA CAR-electroporated T cells (1E7) expressing ss1-bbz were injected twice weekly for 2 weeks. Controls were injected with either RNA CAR T cells expressing CD19-bbz RNA CAR or saline. On day 78 the luminescence signal was significantly decreased in ss1-bbz mice compared to CD19-bbz mice (P<0.01). The above studies indicate that biweekly injections of RNA CAR T cells can control advanced flank and i.p. tumors. Cancer Res. 70(22), 2010, p9053.
Gene Editing: CRISPR
Strong Cell Viability Post Transfection
Low Cytotoxicity in Primary Cells
Figure 5: Transfection of HSC with mRNA-Cas9-gRNA has Low Cytotoxicity. HSC cells were electroporated two days after thawing. A) Viability and B) Proliferation of HSC transfected with mRNA-Cas9-gRNA and mRNA-GFP. Relative to control cells, high viability and proliferation were achieved for HSC using the MaxCyte GT system.
Efficient Gene Editing with Cas9 RNP Electroporation of Human HSPCs
Figure 6: High Efficiency Gene Editing of Two Loci in HSPCs. Cas9 RNPs targeting either AAVS1 or CXCR4 were delivered by MaxCyte electroporation. Briefly, primary human hematopoietic stem and progenitor cells (HSPCs) were resuspended in MaxCyte electroporation buffer, transferred to OC-100 processing assemblies and electroporated according to an optimized protocol with the MaxCyte GTx instrument. Following recovery and overnight culture, DNA was isolated from bulk cells, amplified by PCR, and cleavage efficiencies estimated by T7E1 assay. Gene editing efficiencies were high, given the accepted limits of sensitivity of the T7E1 assay, 67% for CXCR4 and 58% for AAVS1. (Marker = DNA ladder; No EP = non-electroporated cells; EP Only = Cells electroporated without CRISPR RNP; Cas9 Only = Cells electroporated without gRNA). Adapted from Genes (Basel). 2020;11(12):1501.
Summary
- MaxCyte electroporation is a universal cell engineering technology that supports the development and manufacturing of viral vectors and T cell therapies, including gene editing-mediated cell modification.
- MaxCyte cell engineering technology efficiently transfects a variety of cell types, including historically difficult-to-transfect primary cells, with low levels of cell cytotoxicity.
- MaxCyte flow electroporation® has the safety, efficiency and scalability to support cell therapy and gene editing development from early R&D through patient treatment.
- Production scale-up from the MaxCyte STx to the MaxCyte VLX is seamless. High cell viability and transfection efficiencies are maintained without the need for re-optimization.
- MaxCyte electroporation has the reproducibility and scalability for use in biomanufacturing.
- MaxCyte electroporation offers non-viral engineering of T cells that have in vitro and in vivo anti-tumor activity.
- MaxCyte instruments are computer-controlled, cGMP-compliant systems with US FDA & Health Canada Master files enabling simplified migration to the clinic.
