Generation of induced pluripotent stem cells from neonatal mouse cochlear cells

The sensory epithelium (SE) within the mammalian cochleae has a limited capacity for regeneration, and the loss of mammalian cochlear hair cells always lead to permanent hearing loss. Previous reports show that early postnatal cochlea harbors stem/progenitor-like cells nominated otospheres which have a limited regenerative/repair capacity, while these cell populations are progressively lost during the postnatal development. Induced pluripotent stem cells (iPS cells) directly reprogrammed from non-embryonic cells have captured great attentions in the scientific community. In the present study, we determine whether Yamanaka׳s factors can induce the reprogramming of cochlear cells into iPS cells. We introduce defined factors Oct3/4, Sox2 and Klf4 into otospheres derived from postnatal day-1 (P1) mouse SE, and analyze characteristics alterations in cochlear cells. After transduction, otospheres generated colonies exhibiting a normal karyotype and morphology similar to that of mouse embryonic stem cells (ESCs). Moreover, these cochlear iPS cells also express ESC-like markers. Importantly, the cochlear iPS cells show pluripotency in vitro and in vivo, as evidenced by differentiation into three germ layers by embryoid body formation, as well as high efficient formation of teratomas containing three germ layers in immunodeficient mice. Thus, pluripotent cochlear iPS cells can be generated from cochlear cells by using three Yamanaka׳s transcription factors. These attempts represent the first step toward generating fully pluripotent iPS cells from mammalian cochleae with defined exogenous genes.