Protein expression of Oct4, SSEA1, GFAP, Sox2, and Nestin was also identified by western blotting and immunofluorescence (Fig. are widely shown in mesenchymal cells. Moreover, MUCs expressed genes and proteins that are usually presented in prosensory epithelial cells and stem cells. These MUCs showed potential to differentiate into epithelial cells via a reverse EMT when they were forced to suspend in culture medium. Our findings reveal that sensory epithelial cells from mammalian tissue can undergo an EMT to become cells expressing features of stem cells that can be induced to become epithelial cells via a reverse EMT. The outcomes of this study may provide a novel approach to generate epithelial progenitors for use in cell replacement therapy to treat a number of human diseases, such as hearing loss and vision loss. == Introduction == During development, prosensorycells in the otocyst develop into inner ear sensory epithelial cells. Inner ear sensory epithelia are mainly composed of supporting cells and hair cells, which are primarily responsible for detection of auditory and vestibular information. However, mammalian sensory epithelial cells are vulnerable to a number of insults leading to permanent degeneration that cause hearing loss, tinnitus, vestibular problems, and other inner ear disorders. Currently, 2 major approaches are proposed for sensory epithelia regeneration. The Stearoylethanolamide first strategy is to introduce exogenous cells into the inner ear with the hope of replacing the function of damaged auditory system [1,2]. The second approach is to activate local sensory Mouse monoclonal to ERBB3 epithelial progenitors to differentiate into new sensory epithelial cells [35]. Generation of an in vitro sensory epithelial progenitor model directly from inner ear tissues will, therefore, facilitate the study of activation, proliferation, and differentiation of sensory epithelial progenitor. Sphere-forming cells have been identified from mammalian inner ear, which have the potentials to proliferate and become cells expressing sensory epithelial markers [6,7]. However, sphere-forming cells are cultured in suspension medium with relatively limited proliferation ability. The present research focuses on inducing mammalian sensory epithelia to become proliferative progenitors in vitro. Well-differentiated epithelial cells such as inner ear sensory epithelia usually lack the Stearoylethanolamide ability to proliferate, whereas mesenchymal cells retain the capability of dividing. During development, epithelial to mesenchymal transition (EMT) is essential in the formation of the body plan and generation of tissues and organs. In adults, EMT plays an important role in tissue repair, organ fibrosis, and carcinoma progression. These observations lead to the question: can in vitro cultured epithelial cells undergo an EMT to become mesenchymal-like cells with the capability of proliferation? Indeed, when epithelial cells from pancreatic islet are cultured on 2-dimensional (2D) substrates in vitro, they de-differentiate into mesenchymal-like cells that can be expanded to a Stearoylethanolamide large number for use in regeneration study [8,9]. In our previous efforts for inner ear regeneration, utricle epithelial cells from avian embryos are found to undergo an EMT to proliferate and subsequently become sensory epithelial cells through a reverse EMT, mesenchymal-to-epithelial transition (MET) [10]. Since avian inner ear sensory epithelium is known to be able to regenerate, it might not be surprising to observe that these cells are able to proliferate via EMT. It is more challenging to study whether sensory epithelial cells from adult mammals, which are usually unable to regenerate, can undergo a similar process of EMT and consequently obtain the ability to proliferate [11]. Therefore, our hypothesis is that cell phenotype change may contribute to the generation, proliferation, and differentiation of inner ear sensory epithelial progenitors. Mesenchymal status has recently been observed to be essential for the acquisition and maintenance of multi-/pluri- potency of cancer stem cells and/or Stearoylethanolamide embryonic stem (ES) cells. In cancer study, it is found that immortalized epithelial cells acquire cancer stem cell-like properties via EMT that may also contribute to cancer metastasis [12,13]. EMT is observed in human ES (hES) cells grown on matrigels, in which hES cells start to express mesenchymal markers while retaining the expression of pluripotent markers such as Oct4 and Nanog [14]. However, it remains to be determined whether epithelial cells from mammalian sensory system are able to acquire features of stem/progenitor cell via EMT. This is the first step for an effective regeneration strategy. For the next step, we will use these stem/progenitor cells to produce large numbers of new sensory epithelial cells, such as inner ear hair cells and retinal rod cell. In this study, we use adult mouse inner ear sensory epithelial cells as a model to address the.