Long-term culture and partial characterization of dog gallbladder epithelial cells

Abstract

We describe the successful isolation and maintenance of primary cultures of dog gallbladder epithelial cells. The surgically removed gallbladder was treated with trypsin/EDTA for 45 minutes and epithelial cells were collected and resuspended in Eagle's minimum essential medium with 10% fetal calf serum, and plated on Vitrogen-coated culture dishes. Each gallbladder yielded approximately 12 to 15 X 106 columnar epithelial cells, >95% of which were viable by trypan blue exclusion. In culture, cells maintained their polarity. They were arranged and grew in small and tight clusters that coalesced at confluency. When examined using transmission electron microscopy, prominent and numerous microville were identified on the apical portion of the plasma membrane. Cells were connected by well-formed desmosomes. Scanning electron microscopy revealed clusters of polyhedral cells with numerous papillary projections. Immunohistochemical studies demonstrated uniform staining of cells to keratin 35BH11 and AE1. Histochemical studies were positive for γ-glutamyl transpeptidase and negative for glucose-6-phosphatase and albumin. Cells incorporated [3H]uridine into intracellular proteins and [14C]glucosamine into tissue and secreted mucous glycoproteins linearly over 2 to 24 hours. Flow cytometry studies demonstrated a consistent and reproducible number of cells (10 to 12%) at S-phase. However, the number of cells at S-phase was dramatically reduced to almost negligible as cells reached confluency. This method of culturing primary dog gallbladder epithelial cells is highly reproducible and reliable. These cells preserve their state of differentiation, polarity, histochemical and immunohistochemical profile, morphologic, and metabolic integrity with repeated passaging or after being frozen. [3H]Thymidine uptake is well maintained, although doubling time shows a trend of decreased cell duplication with time. This technique offers the opportunity to study the electrophysiologic, metabolic, and immunologic properties of epithelial cells.