F. Scorletti1, M. Oria1, F. Y. Lim1, J. L. Peiro1 1Cincinnati Children’s Hospital Medical Center,The Center For Fetal, Cellular And Molecular Therapy,Cincinnati, OH, USA
Introduction: Gastroschisis (GS) patients have high morbidity secondary to intestinal dysmotility and malabsorption that require parenteral nutrition for a long period. Main alterations in the extruded bowel include edema and inflammation caused by amniotic fluid contact. Sufficient lymphatic clearance plays a crucial role in clearing the inflammation process, while lymphatic failure is believed to intensify the intestinal edema. Our aim was to investigate the intestinal lymphatic system alteration in a rabbit GS experimental model.
Methods: IACUC#2013-0294. Gastroschisis was surgically created on fetal New-Zealand rabbits at E24 and harvested on day E30 (term=31days). The siblings were collected as controls (n=10 per group). Body and intestinal weights (BW, IW), their ratio (IBR) and dry test were performed. RNA was isolated and pellets were partially re-extracted, precipitated, DNAseI-digested and cleaned. A 1-µg cDNA sample was used to set up RT-qPCR using primers for VEGF-C, VEGFR3 and GAPDH. Histology, immunofluorescence (IF) and western blotting (WB) were assessed to VEGF-C (Vascular Endothelial Growth Factor), VEGFR-3 (receptors), SMA (Smooth Muscle Actin) in GS eviscerated bowel and controls.
Results: IW, IBR and water (in dry test) were significantly increased (p<0.005) in the exposed GS intestine [1.391 (±0.208) versus 1.029 (±0.156); 0.041 (±0.004) versus 0.036 (±0.003); 96.08 (±1.13) versus 80.36 (±6.26), respectively]. VEGF-C and VEGFR3 gene expression were down-regulated in exposed GS especially at early stages respect time matched controls (p<0.05). Whereas, VEGFR-3 and SMA were increased (p<0.05) in GS pups versus controls. VEGFR-3 staining showed a different distribution of lymphatic vessel receptors decreasing on muscular and subserosa layers to be increased on intestinal villi.
Conclusion: Exposed bowel in GS showed more water content suggesting edema. VEGF-3/VEGFR-3 is the primary trophic signal for the proper development and maintenance of the intestinal lymphatic vessels. We hypothesize that these changes in expression and structure of this pathway can be intent to decrease the permeability of lymphatic vessels to canalize the excess of edema. Those disturbances could alter the integrity of the intestinal lymphatic vessel network. The failure to adequately clear lymph from the intestine wall may sustain and intensify intestinal inflammation and edema. Additionally, impaired lymphatic system development may also explain the poor absorption in babies with gastroschisis.