R11, a novel cell-permeable peptide, as an intravesical delivery vehicle.

OBJECTIVE: To test the uptake efficiency of R11, a cell-permeable peptide (CPP), administered intravesically for effective drug delivery.
METHODS: We used an approved in vivo model (an athymic nude mouse model) to test synthetic R11 conjugated with fluorescein isothiocyanate (FITC) at concentrations of 1 nM and 5 nM. Controls received FITC without CPP conjugation. The mice were instilled with R11 for 30 min and killed 3 or 24 h later to harvest bladders for the measurement of CPP uptake and tissue localization using frozen sections. Bladder uptake specificity was determined using the mean values of relative FITC intensity with each tissue weight.
RESULTS: Although the uptake of R11 varied among the mice, a 2- to 6-fold higher amount of R11 was detected in the bladder at 3 and 24 h after intravesical instillation at 1-nM or 5-nM concentrations than was detected in the bladders of each mouse control group or in other organs. Examination of tissue sections further confirmed the localization of R11 in the lamina propria of the bladder wall.
CONCLUSION: Because of its high affinity for the bladder, both systemically as reported in previous studies and after intravesical instillation as reported in the present study, R11 should be further tested in animal models as a delivery vector for agents used in treating bladder diseases.