Scientific Publications
The Influence of Small Intestinal Mucus Structure on Particle Transport ex vivo
Colloids and Surfaces B: Biointerfaces, 135, 73-80
Mucus provides a barrier to bacteria and toxic compounds while allowing nutrient absorptionand waste transport. Unlike the colonic mucus layer, small intestinal mucus structure ispoorly understood. This study aimed to provide evidence for a continuous mucus layer,significant structure to this layer and assess the diffusion of different sized nano-particles through the layer. Small intestinal samples from pigs and mice were collected. Frozen or fixed sections were used to assess mucus structure using PAS/Alcian Blue and anti-MUC2 immunohistochemistry. Ultra-structure of mouse intestine was assessed by scanning electron microscopy. Tracking of 100nm and 500nm latex beads was conducted ex vivo using scraped porcine small intestinal mucus.The lumen of unfixed porcine jejunum and ileum were filled with mucus. Layered MUC2 staining was visible throughout the small intestine, covering the villus tips. Scanning electron microscopy showed net-like mucin sheets covering villi with a mean pore size of 211nmdiameter. Particle tracking of 100nm latex beads, showed no inhibition of diffusion through ex vivo porcine mucus while up to 50% of 500nm beads did not diffuse. These results suggest that a continuous mucus layer exists throughout the small intestine and has a stratified structure adjacent to the epithelium. The mesh network observed by SEM is consistent with the previous observations and correlates with the stratified MUC2 staining patterns. A mucin pore diameter of 200-250nm is consistent with the free diffusion of 100nm particles and the limited diffusion of 500nm particles. Small Intestinal mucus structure may have important implications for drug delivery systems and functionalized foods and for the prevention and treatment of conditions such as mucositis and inflammatory bowel disease.
Colloids and Surfaces B: Biointerfaces, 135, 73-80
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