Production of High-Yield Adeno Associated Vector Batches Using HEK293 Suspension Cells
Summary
Here, a suspension HEK293 cell-based AAV production protocol is presented, resulting in reduced time and labor needed for vector production using components that are available for research purposes from commercial vendors.
Abstract
Adeno-associated viral vectors (AAVs) are a remarkable tool for investigating the central nervous system (CNS). Innovative capsids, such as AAV.PHP.eB, demonstrate extensive transduction of the CNS by intravenous injection in mice. To achieve comparable transduction, a 100-fold higher titer (minimally 1 x 1011 genome copies/mouse) is needed compared to direct injection in the CNS parenchyma. In our group, AAV production, including AAV.PHP.eB relies on adherent HEK293T cells and the triple transfection method. Achieving high yields of AAV with adherent cells entails a labor- and material-intensive process. This constraint prompted the development of a protocol for suspension-based cell culture in conical tubes. AAVs generated in adherent cells were compared to the suspension production method. Culture in suspension using transfection reagents Polyethylenimine or TransIt were compared. AAV vectors were purified by iodixanol gradient ultracentrifugation followed by buffer exchange and concentration using a centrifugal filter. With the adherent method, we achieved an average of 2.6 x 1012 genome copies (GC) total, whereas the suspension method and Polyethylenimine yielded 7.7 x 1012 GC in total, and TransIt yielded 2.4 x 1013 GC in total. There is no difference in in vivo transduction efficiency between vectors produced with adherent compared to the suspension cell system. In summary, a suspension HEK293 cell based AAV production protocol is introduced, resulting in a reduced amount of time and labor needed for vector production while achieving 3 to 9 times higher yields using components available from commercial vendors for research purposes.
Introduction
Adeno-associated virus (AAV) was discovered in 1965 and has since been used in a myriad of applications1. AAVs have been applied in neuroscience research to study gene and neuronal function, map neurocircuits, or produce animal models for disease2. Traditionally, this is done by injecting directly at the site of interest, as most natural serotypes do not cross the blood-brain barrier or need a high dose to do so1,2,3.
With the discovery of AAV.PHP.B4 and next-generation capsids such as AAV.PHP.eB5 and AAV.CAP-B106, it is possible to target the central nervous system (CNS) using a simple systemic injection. Spatial mapping reveals the cells targeted by AAV.PHP.eB at cellular level6,7. In combination with specific promoters/enhancers, these capsids offer extensive opportunities for neuroscientists to study genes and brain function by non-invasive AAV delivery4,8.
While a lower dose is needed for AAV.PHP.eB (typically 1 to 5 x 1011 Genome Copies (GC)/mouse) compared to AAV9 (4 x 1012 GC/mouse)7, still more vector needs to be produced compared to direct injection strategies (typically 1 x 109 GC/µL injection). Most natural serotypes can be produced using the classical adherent cell culture system in combination with iodixanol purification9,10,11,12. For AAV.PHP.eB this entails a labor-intensive process to culture and transfect cells to obtain sufficient vectors for one experiment8. Therefore, the production of AAV in suspension cell culture in conical tubes was developed. Conical tubes, with a capacity of up to 300 mL, are compact, saving both incubator space and plastics. Suspension cells are much easier to culture and handle in large amounts than adherent cells on 15 cm plates. The transfection components of the protocol remain the same. Therefore, plasmids previously used with the adherent system can easily be used in this protocol based on production in suspension cells. The protocol was successfully transferred to other researchers in the laboratory and successfully used for various capsids and constructs.
Protocol
Representative Results
Discussion
Systemic administration of AAV is a powerful tool for gene transfer to the CNS; however, the production of AAV is an expensive and laborious process. By using suspension cells, labor and plastics are reduced compared to the adherent culture of HEK293T on 15 cm2 plates. Furthermore, the conical tubes implemented here are easy to handle and maximize the use of laboratory space. The protocol was set up by two researchers and subsequently applied by others in the lab. A series of productions by three independ…
Divulgations
The authors have nothing to disclose.
Acknowledgements
This work was supported by a grant from the Royal Netherlands Academy of Arts and Sciences (KNAW) research fund and a grant from Start2Cure (0-TI-01). We thank Leisha Kopp for her input and advice in the setup of the protocol. Figures were created using Biorender.
Materials
| 39 mL, Quick-Seal Round-Top Polypropylene Tube, 25 x 89 mm – 50Pk | Beckman Coulter | 342414 | |
| Adapter 600 mL conical tubes, for rotor S-4×1000, | eppendorf | 5920701002 | |
| Adapter Plate fits 16 bioreactors of 600 ml | Infors HT/ TPP | 587633 | |
| Aerosol-tight caps, for 750 mL round buckets | eppendorf | 5820747005 | |
| Centrifuge 5920 R G, 230 V, 50-60 Hz, incl. rotor S-4×1000, round buckets and adapter 15 mL/50 mL conical tubes | eppendorf | 5948000315 | |
| Distilled Water | Gibco | 15230147 | |
| DNase I recombinant, RNase-free | Roche | 4716728001 | |
| DNase I recombinant, RNase-free | Roche | 4716728001 | |
| DPBS, calcium, magnesium | Gibco | 14040091 | |
| DPBS, no calcium, no magnesium | Gibco | 14190144 | |
| Fisherbrand Disposable PES Filter Units 0,2 | Fisher | FB12566504 | |
| Fisherbrand Disposable PES Filter Units 0,45 | Fisher | FB12566505 | |
| Holder for 50 ml culture tubes also fits falcon tube | Infors HT/ TPP | 31362 | |
| Holder for 600 ml cell culture tube | Infors HT/ TPP | 66129 | |
| Incubator Minitron 50 mm | Infors HT | 500043 | |
| LV-MAX Production Medium | Gibco | A3583401 | |
| N-Tray Universal | Infors HT/ TPP | 31321 | |
| OptiPrep – Iodixanol | Serumwerk bernburg | 1893 | |
| PEI MAX – Transfection Grade Linear Polyethylenimine Hydrochloride (MW 40,000) | Poly-sciences | 24765-100 | |
| Phenol red solution | Sigma-Aldrich | 72420100 | |
| Poly(ethylene glycol) 8000 | Sigma-Aldrich | 89510 | |
| TransIT-VirusGEN | Mirus | Mir 6706 | |
| Trypan Blue Solution, 0.4% | Gibco | 5250061 | |
| TubeSpin Bioreactors-50ml | TTP | 87050 | |
| TubeSpin Bioreactors-600ml | TTP | 87600 | |
| Viral Production Cells | Gibco | A35347 | |
| Vivaspin 20 MWCO 100 000 | Cytvia | 28932363 |
References
- Zhou, K., Han, J., Wang, Y., Zhang, Y., Zhu, C. Routes of administration for adeno-associated viruses carrying gene therapies for brain diseases. Front Mol Neurosci. 15, 988914 (2022).
- Pietersz, K. L., et al. PhP.B Enhanced adeno-associated virus mediated-expression following systemic delivery or direct brain administration. Front Bioeng Biotechnol. 9, 679483 (2021).
- Zhang, H., et al. Several rAAV vectors efficiently cross the blood–brain barrier and transduce neurons and astrocytes in the neonatal mouse central nervous system. MolTher. 19 (8), 1440-1448 (2011).
- Deverman, B. E., et al. Cre-dependent selection yields AAV variants for widespread gene transfer to the adult brain. Nat Biotechnol. 34 (2), 204-209 (2016).
- Chan, K. Y., et al. Engineered AAVs for efficient noninvasive gene delivery to the central and peripheral nervous systems. Nat Neurosci. 20, 1172-1179 (2017).
- Goertsen, D., et al. AAV capsid variants with brain-wide transgene expression and decreased liver targeting after intravenous delivery in mouse and marmoset. Nat. Neurosci. 25 (1), 106-115 (2022).
- Foust, K. D., et al. Intravascular AAV9 preferentially targets neonatal neurons and adult astrocytes. Nat Biotechnol. 27 (1), 59-65 (2008).
- Challis, R. C., et al. Systemic AAV vectors for widespread and targeted gene delivery in rodents. Nat Protoc. 14 (2), 379-414 (2019).
- Fripont, S., Marneffe, C., Marino, M., Rincon, M. Y., Production Holt, M. G. purification, and quality control for adeno-associated virus-based vectors. J Vis Exp. (143), e58960 (2019).
- Fagoe, N. D., Eggers, R., Verhaagen, J., Mason, M. R. J. A compact dual promoter adeno-associated viral vector for efficient delivery of two genes to dorsal root ganglion neurons. Gene Thr. 21 (3), 242-252 (2014).
- Verhaagen, J., et al. Retinal gene therapy, methods and protocols. Meth Mol Biol. 1715, 3-17 (2018).
- Nasse, J. S., et al. Addgene AAV data hub: A platform for sharing AAV experimental data. Nat Meth. 20 (9), 1271-1272 (2023).
- Grieger, J. C., Soltys, S. M., Samulski, R. J. Production of recombinant adeno-associated virus vectors using suspension HEK293 cells and continuous harvest of vector from the culture media for GMP FIX and FLT1 clinical vector. Mol Ther. 24 (2), 287-297 (2016).
- Blessing, D., Déglon, N., Schneider, B. L. Recombinant protein expression in mammalian cells, methods and protocols. Meth Mol Biol. 1850, 259-274 (2018).
