Measles virus as a tool for iPSC-independent tissue specific reprogramming

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 DESCRIPTION: Induced pluripotent stem cell technology, which allows reprogramming of cell fate through ectopic expression of selected transcription factors, has opened the possibility to reprogram fibroblasts or other somatic cells directly into specific cell types. This direct reprogramming offers an alternative approach for generating lineages of interest without passing through a progenitor state. Similar to the pluripotent reprogramming by the Yamanaka factors, the process to convert fibroblasts directly to neuronal cells, hepatocyte-like cells, insuin producing-cells or cardiomyocyte-like cells requires the delivery of multiple transcription factors into the cells. Several vectors, such as retroviral-, lentiviral-, AAV-vectors or plasmids, have been used for this purpose with different levels of success, but with the potential of integration f genetic material in the host genome. Thus, there is a need for the development of a new viral platform to generate transgene-free direct reprogrammed cells. Here, we propose to develop a new RNA vector system based on a non-integrating human Paramyxovirus, measles virus (MV), to deliver the transcription factors needed for the direct reprogramming of fibroblast into insulin producing cells. We have developed a reverse genetic system allowing the production of a recombinant virus equivalent to the Moraten vaccine strain, which is currently used for vaccination in the US. From this viral genome, we have produced a "one cycle" vector and used it to express the Yamanaka factors for iPSCs reprogramming. We propose to modify these vectors and use them to express the factors required for direct reprogramming. We will test the hypothesis that our replication-deficient measles vector can be modified to express the transcription factors shown to be necessary for the reprogramming of adult somatic cells into functional insulin-producing cells. The cells will be then tested in a diabetic mouse model that will validate the functionality of the reprogrammed insulin producing cells. Achieving the proposed studies outlined here will lead to the development of a new polycistronic vector platform allowing direct trans-differentiation without genomic modification. These studies will open the perspective of using these vectors for future direct reprogramming in vivo.