Single non-integrating RNA vector for gene editing and reprogramming of Fanconi anemia fibroblasts

摘要。

Abstract. The recent advances in induced pluripotent stem cells (iPSCs) and gene therapy tools have opened up a new avenue to study and treat diseases, particularly of disorders with defective bone marrow. Bone marrow failure syndromes (BMFS) are characterized by reduced blood cells due to a dysfunctional bone marrow cells. Fanconi anemia (FA) is one such bone marrow failure syndrome where cellular reprogramming is inefficient, owing to interference of the disease-related genes. To overcome this limitation, it is necessary to fundamentally correct the abnormal gene (e.g.: FANCD1) during or prior to the reprogramming process. In the past, obtaining genetically modified iPSC from the fibroblasts of these patients typically involved multiple steps. But recent progress in the field has paved way for simultaneous reprogramming and gene targeting in a single step using multiple episomal vectors. In this study we propose to transform the multiple vector-single step procedure to a single vector-one step approach to obtain corrected iPSC from FA fibroblasts. Our single vector is based on a non-integrating negative strand RNA virus, Measles virus (MV). The central hypothesis is that a MV vectors can be designed to express all components in one genome, and lead to the generation of clinically safe, corrected and functional iPSCs from FA fibroblasts. The rationale for the proposed research is that the “one-cycle” MV vector, MV4F, expressing the four reprogramming factors, generate iPSC from human fibroblasts and is quickly diluted and eliminated from the iPSC after reprogramming. Guided by strong preliminary data, the specific aim of this particular application is to produce a set of one-cycle “all-in-one” MV vectors, containing the four reprogramming factors plus Cas9-gRNA, and setup the protocol to concurrently reprogram and edit the genome of human fibroblasts carrying a genetic mutation. The proposed work is innovative, because it capitalizes on a new technology that relies on a single vector expressing the four reprogramming factors (RFs) for the reprogramming of somatic cells into iPSC; and our group developed that technology. Finally, the corrected iPSC will be tested for their ability to differentiate into hematopoietic stem cells. The proposed work is significant because we develop a new single vector for the production of corrected iPSC, that will be eliminated quickly from the established iPSC and that can be rapidly translated into the clinic, as it is based on the safe measles vaccine strain. Finally, the proposed research is relevant to that part of NIH’s mission that pertains to develop new treatments for inherited bone marrow failure syndromes, hemoglobinopathies, immunodeficiencies, and other monogenetic disorders to reduce the burden of human disease.