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Updated: Jun 8, 2026
10:14
Retroviral Transduction of T-cell Receptors in Mouse T-cells
Published on: October 22, 2010
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Inadvertent Transfer of Murine VL30 Retrotransposons to CAR-T Cells
Sung Hyun Lee1, Yajing Hao2, Tong Gui1
1Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Advances in Cell and Gene Therapy
|September 9, 2022
Summary
Murine packaging cells used in CAR-T therapy may contaminate T-cells with potentially oncogenic VL30 retrotransposons. This study found infectious VL30 particles in clinical-grade CAR-T cells, raising biosafety concerns for current cancer treatments.
Area of Science:
- * Molecular Biology
- * Immunotherapy
- * Virology
Background:
- * Genetically engineered autologous T-cells, specifically chimeric antigen receptor T-cells (CAR-Ts), are a successful immunotherapy for blood cancers.
- * CAR-Ts are often engineered using gamma-retroviral vectors (γ-RVVs) produced by murine packaging cell lines, such as PG13.
- * Previous research indicated that murine virus-like 30S RNA (VL30) genomes can be copackaged with γ-RVVs and may enhance cancer metastasis.
Purpose of the Study:
- * To investigate the presence and potential biosafety risks of VL30 retrotransposons in CAR-T cells derived from murine packaging cell lines.
- * To assess the infectivity and transcriptional activity of VL30 particles generated in PG13 cells.
- * To determine if VL30 genomes are transferred and expressed in clinical-grade CAR-T cells.
Main Methods:
- * Detection of infectious VL30 particles in conditioned media from PG13 packaging cells.
- * Transduction of human cells with VL30 genomes packaged by HIV-1-based vector particles.
- * Analysis of VL30 genome transfer and expression in clinical-grade CAR-T cells produced using PG13-derived γ-RVVs.
Main Results:
- * Infectious VL30 particles were identified in PG13 cell-conditioned media.
- * These VL30 particles demonstrated the ability to deliver transcriptionally active VL30 genomes to human cells.
- * VL30 genomes were successfully transferred and expressed in clinical-grade CAR-T cells.
Conclusions:
- * The use of murine packaging cell lines like PG13 in the production of therapeutic CAR-T cells poses a biosafety risk due to potential VL30 retrotransposon contamination.
- * VL30 retrotransposons can be infectious and transcriptionally active, raising concerns about their oncogenic potential in patients receiving CAR-T therapy.
- * Further research and safety assessments are warranted for the clinical application of CAR-T cells produced using murine packaging cell lines.
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As the name suggests, non-LTR retrotransposons lack the long terminal repeats characteristic of the LTR retrotransposons. Additionally, both LTR and non-LTR retrotransposons use distinct mechanisms of mobilization. Non-LTR retrotransposons are further divided into two classes - Long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), both of which occur abundantly in most mammals, including humans. Some of the active non-LTR retrotransposons in humans are L1...