Most of the drugs used in the treatment of inflammatory bowel disease (IBD) become systemically bioavailable and potentially bear strong adverse effects. Targeting the inflamed areas of the intestine and keeping the drug localised at its site of action can reduce adverse effects. In animal studies, luminal uptake into inflamed mucosal areas has been shown to be size dependent. We investigated the potential of nano- and microparticle uptake into the rectal mucosa of human IBD patients. Fluorescently labelled placebo nanoparticles (NP) 250nm in size and microparticles (MP) 3.0μm in size were prepared. 2h after rectal application to patients with Crohn's disease (CD) or ulcerative colitis (UC), confocal laser endomicroscopy was performed to visualise the particles in inflamed mucosal areas. In biopsies, ex vivo mucosal transport processes were investigated in miniaturised Ussing chambers. We examined 33 patients with IBD (19 patients with CD, 14 patients with UC) and 6 healthy controls. A significantly enhanced accumulation of MP in ulcerous lesions was observed (covered area=1.28% (range 0.83%-3.45%) vs. 0% in controls; p=0.011), while NP were visible only in traces on mucosal surfaces of all patients. The Ussing chamber experiments suggest persorption of particles through cellular voids; statistical significance was only reached for NP. Drug-containing particles may have great potential to more specifically target intestinal lesions to maximise therapeutic efficacy and minimise potential side effects. Nanoparticles may not be required for local drug delivery to intestinal lesions in humans, thereby minimising the risk of unintended translocation into the blood system.
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