Genotoxicity assay for gene therapy vectors in tumor prone Cdkn2a⁻/⁻ mice

Abstract

Integrative viral vectors are able to efficiently transduce hematopoietic stem progenitor cells allowing stable transgene expression in the entire hematopoietic system upon transplant in conditioned recipients. For these reasons, integrative vectors based on γ-retroviruses and lentiviruses have been successfully used in gene therapy clinical trials for the treatment of genetic diseases, especially blood disorders. However, in different γ-retroviral-based clinical trials, vector integration into the host cell genome triggered oncogenesis by a mechanism called insertional mutagenesis. Thus, a thorough reassessment of the safety of available gene transfer systems is a crucial outstanding issue for the whole gene therapy field. Sensitive preclinical models of vector genotoxicity are instrumental to achieve a more detailed understanding of the factors that modulate the risks of insertional mutagenesis. Here, we will describe the methodologies used to address the mutagenesis risk of vector integration using a murine in vivo genotoxicity assay based on transduction and transplantation of tumor-prone hematopoietic stem and progenitor cells.