Method of nuclear reprogramming

Abstract

A method of producing an induced pluripotent stem cell includes introducing into a somatic cell one or more non-viral expression vectors. The vectors include one or more of an Oct family gene, a Klf family gene, a Sox family gene, a Myc family gene, a Lin family gene, and Nanog gene. The somatic cell is then cultured in a medium that supports pluripotent stem cells. At least a portion of the one or more introduced non-viral expression vectors is not substantially integrated in the chromosome.

What is claimed is: 
     
         1 . A method of producing human induced pluripotent stem (iPS) cells population and having cells where the vector is not integrated into the genome, the method comprising the steps of
 a) obtaining a starting population of human somatic cells;   b) obtaining one or more iPS reprogramming vectors comprising a DNA sequence that allows the autonomous replication of the expression vector outside a chromosome in a somatic cell and one or more expression cassettes encoding iPS reprogramming factors;   c) introducing the iPS reprogramming vector(s) into the human somatic cells;   d) culturing the human somatic cells that comprise the iPS reprogramming vector(s) to effect expression of said reprogramming factors such that traits consistent with embryonic stem cells arise in at least a portion of cells in the cultured cells; and   e) further culturing cells having the embryonic stem cell traits for a sufficient number of generations in the absence of positive selection for the presence of the iPS reprogramming vector(s) to provide human iPS cells that are essentially free of iPS reprogramming vector genetic elements.   
     
     
         2 . The method of  claim 1 , wherein cells of the starting cell population are fibroblasts, keratinocytes, hematopoietic cells, mesenchymal cells, liver cells, stomach cells, or β cells. 
     
     
         3 . The method of  claim 1 , wherein the iPS reprogramming factors comprise Sox-2 and Oct-4. 
     
     
         4 . The method of  claim 3 , wherein the reprogramming factors further comprise Nanog or Lin28. 
     
     
         5 . The method of  claim 1 , further comprising a step of differentiating the human iPS cells provided in step e).