β1 Integrin Expression Pattern in Transitional Urothelium Does Not Allow for Efficient Stem Cell Enrichment as in Other Epithelia

With a lack of distinct stem cell markers, isolation of tissue-specific stem cells for tissue engineering and gene therapy is a great challenge. Beta (β)₁ integrin expression has been used as a way of enriching for putative epithelial stem cells through rapid adhesion to collagen IV or flow cytometry. This is a first report of enrichment of putative urothelial stem cells using rapid adhesion and flow cytometric methods. We assessed our success by determining the clonogenic and proliferative potential of the isolated cells. We demonstrated that enrichment based on β₁ integrin expression with flow cytometry yields highly clonogenic and proliferative urothelial cells, whereas the rapid adhesion method is not as efficient, possibly because of the unique nature of urothelium, a transitional epithelium, compared to results reported in stratified and columnar epithelia.