Optimisation of the formation and distribution of protoporphyrin IX in theurothelium: An in vitro approach

Purpose: To optimize conditions for photodynamic detection (PDD) and photod ynamic therapy (PDT) of bladder carcinoma, urothelial accumulation of proto porphyrin IX (PpIX) and conditions leading to cell photodestruction were st udied. Materials and Methods: Porcine and human bladder mucosae were superfused wi th derivatives of 5-aminolevulinic acid (ALA), PpIX accumulation and distri bution across the mucosa was studied by microspectrofluorometry. Cell viabi lity and structural integrity were assessed by using vital dyes and microsc opy, Results: ALA esters, especially hexyl-ALA, accelerated and regularized urot helial PpIX accumulation and allowed for necrosis upon illumination. Conclusions: hexyl-ALA used at micromolar concentrations is the most effici ent PpIX precursor for PDD and PDT.