The effect on the intestines of continuous release of methylene blue from a drug delivery system: an experimental study in a chick embryo gastroschisis model.

Abstract

Increased small bowel nitric oxide synthase (NOS) activity has been suspected as a cause of postnatal intestinal dysmotility in gastroschisis. The effect of continuous delivery of methylene blue loaded polymer (MBLP) hydroxy-propyl methyl cellulose-ethyl cellulose (HPEC-MC) and daily injection of methylene blue (MB) on the intestinal damage (ID) was evaluated using a chick embryo gastroschisis model. Fourteen-day-old fertilized chick eggs were divided into five groups. In the control (C) group, no intervention was performed. In the sham (S) group, the allantoic and amniotic membranes were opened to create a common cavity that resembles the amniotic cavity in human. In the gastroschisis only (GO) group, a defect in the abdominal wall of the embryo was made, and intestinal loops were exteriorized following connection of amniotic and allantoic cavities. In the gastroschisis plus methylene blue (G+MB) group, gastroschisis was created and MB administered into the amnioallantoic cavity (AAC) by daily injections for 5 days. In the gastroschisis plus methylene blue loaded polymer (G+MBLP) group, MBLP was placed into AAC after gastroschisis was created. At the end of the 19th day of incubation, intestinal morphological changes were investigated macroscopically and microscopically. Although the survival rates were decreased in the chick embryos with creation of gastroschisis compared with C and S groups ( p<0.001), the survival rates were increased in G+MBLP group (76.92%) when compared with the GO group (41%) ( p<0.001). Because of multiple intervention of embryos, higher mortality was observed in the G-MB group (75.61%). Macroscopic and microscopic scores of ID and mean intestinal wall thickness were significantly higher in the GO group when compared with C, S, G+MB, and G+MBLP groups ( p<0.001). The mean score of intestinal ganglia morphology was significantly increased and the total number of ganglion cells was significantly decreased in the GO group when compared with C, S, G+MB, and G+MBLP groups ( p<0.001). It is possible to decrease intrauterine intestinal morphological changes in gastroschisis by inhibiting NOS. As a first preliminary study, we believe that use of MBLP may be an alternative for fetal treatment by eliminating the harmful effects of multiple interventions or amniotic fluid exchanges.