Studies on adult mouse and human olfactory derived neural progenitors

The olfactory neuroepithelium (ONe) has a unique life-long regenerative capacity due to the presence of stem cells capable of mitotic division, which replace damaged or lost cellular components. The ONe is readily accessible through the nasal cavity, which can facilitate biopsies for the isolation of stem cells for further evaluation and manipulation in vitro prior to transplantation. Previous studies in our lab have demonstrated that ZnSO4 injury applied to ONe of adult mice stimulated mitotic activity of the stem cells which could be propagated in vitro. These cells had heterogeneous phenotypes (Sosnowski et al., 1995; Liu et al, 1998). The lab also established cell lines from adult human ONe derived from cadavers (Roisen et al., 2001) and patients undergoing endoscopic nasal sinus surgery (Winstead et al., 2005) that formed heterogeneous neurospheres. The purposes of the present study were (1) to characterize the ONe from green fluorescent protein (GFP) mice both in vivo and in vitro, (2) to separate a subpopulation of neuroprogenitors from the human neurosphere forming cell lines, and (3) to characterize the neurosphere forming cells (NSFCs) from human ONe subcultures and to study their progenitor nature. Characterization of ONe cells from GFP mice revealed the cytoarchitecture of the ONe in situ was similar to its mammalian counterparts. Cultures were established from ONe following ZnSO4 exposure, which contained a heterogeneous population of fluorescent NSFCs. The endogenous GFP fluorescence of these cells could provide a readily identifiable label that would facilitate their recognition following transplantation into non-transfected hosts. When human NSFCs were separated with Trk-pan antibody, two subpopulations of cells were obtained which were either positive or negative to Trk-pan. Both of these subpopulations were viable, and exhibited a neural phenotype. Furthermore using clonal and population analyses, the human NSFCs were examined, to determine their progenitor nature. This study demonstrates that adult NSFCs from both mouse and human ONe provide a unique adult-derived neuroprogenitor cell source which can be readily obtained, manipulated in vitro for use in functional and transplantation studies.