Progenitor/stem cell populations of epithelium are known to reside in the small-sized cell population. Our objective was to physically isolate and characterize an oral keratinocyte-enriched population of small-sized progenitor/stem cells. Primary human oral mucosal keratinocytes cultured in a chemically defined serum-free culture system, devoid of animal-derived feeder cells, were sorted by relative cell size and characterized by immunolabeling for beta1 integrin, nuclear transcription factor, peroxisome proliferator-activated receptor-gamma, and cell-cycle analysis. Sorted cells were distinguished as progenitor/stem cells by functional assays and their ability to regenerate an oral mucosal graft. Small-sized cells demonstrated the lowest expression of peroxisome proliferator-activated receptor-gamma, the highest colony-forming efficiency, a longer long-term proliferative potential, an enriched quiescent cell population, and the ability to regenerate an oral mucosal graft, implying that the small-sized cultured oral keratinocytes contained an enriched population of progenitor/stem cells.

No abstract

The FDA requires an accurate determination of the dose and potency of tissue engineered or combinational products as is required for drugs. This needs to be done as a rapid, quantitative and non-invasive measurement of biological function/activity in a way as not to perturb the tissue engineered product being developed.Purpose-The aim of this study was to correlate constitutive release of cytokine(s) from unstimulated cells, at different stages of development within a three-dimensional (3D) organotypic ex vivo produced oral mucosa equivalent (EVPOME) to be used for intraoral grafting, with oral keratinocyte cell viability of the EVPOME.Materials and methods-Tissue culture media was assayed with an ELISA from monolayer culture of oral keratinocytes and a 3D EVPOME to determine the constitutive release of IL-1α, IL-6, IL-8 and VEGF. VEGF mRNA expression by oral keratinocytes within the 3D EVPOME were detected by in situ hybridization at day 4, 7 and 11. The number of viable oral keratinocytes within the EVPOME was extrapolated from VEGF release using a modified MTT assay. Conclusions-These results suggest that the increasing detectable levels of VEGF associated with the increasing number of viable cells in the EVPOME may provide a useful non-invasive/nondestructive means of assessing both cellular viability (dose) and biological function/activity (potency) of a combinational cell-based device such as the EVPOME. Results-Both

Background: Photodynamic therapy (PDT) is a minimally invasive treatment modality for early