Electromotive diffusion (EMD) and photodynamic therapy with delta-aminolaevulinic acid (delta-ALA) for superficial...

Recent reports have shown that topical application of delta-aminolaevulinic acid (delta-ALA) can be used for the photodynamic diagnosis and therapy of superficial bladder tumours. Electromotive diffusion (EMD) increases the cellular uptake of polar substances. In six patients with biopsy-proven recurrent carcinoma in situ of the bladder after Bacillus Calmette-Guérin (BCG) treatment, 100 cm3 of a 0.5% delta-ALA solution at pH approximately 6 was instilled into the bladder. With a special Foley catheter containing a stainless steel electrode, EMD, with a 15 mA, pulsed current, positive polarity at the catheter, was created for 20 min in the sedated patient. Thereafter a laser fibre with a spheric diffuser was inserted into the bladder over a cystoscope. The bladder surface was irradiated at a wavelength of 632 nm with 350 mW s-1 (total dose, 30-50 J cm-2). Follow-up consisted of a cystoscopy and biopsy after 6 weeks and cystoscopy and cytology every 3 months thereafter. The whole procedure was well tolerated. Currently, five patients are tumour free after a follow-up of 10-16 months. One patient has recurred after 10 months with a Ta G3 superficial tumour at the bladder neck which was resected. In a transwell cell culture model, we investigated the effect of delta-ALA treatment with and without application of EMD. In this in vitro system, application of an electric field showed only a small increase in delta-ALA uptake compared with uptake by passive diffusion.