Gastroschisis in the rat model is associated with a delayed maturation of intestinal pacemaker cells and smooth muscle cells.

Background: A pacemaker system is required for peristalsis generation. The interstitial cells of Cajal (ICC) are considered the intestinal pacemaker, and are identified by expression of the c-kit gene–encoded protein. Gastroschisis is characterized by a severe gastrointestinal dysmotility in newborns. In spite of this clinical picture, few studies have focused on smooth muscle cells (SMC) morphology and none on ICC. Therefore, their morphology has been studied in fetuses at term in the rat model of gastroschisis. Methods: At 18.5 day’s gestation (E18.5), 10 rat fetuses were killed, 10 underwent surgical creation of gastroschisis, and 10 underwent manipulation only. The small intestine of the latter 2 groups was harvested at E21.5. Specimens were processed for H&E, c-kit and actin (alpha smooth muscle antibody [-SMA]) immunohistochemistry, and trasmission electron microscopy (TEM). Results: In the controls, SMC were c-kit and -SMA, with labeling intensity increasing by age. At E21.5, some cells around the Auerbach’s plexus were more intensely c-kit, and differentiating ICC were seen under TEM at this level. Gastroschisis fetuses had no c-kit cells referable to ICC. In the more damaged loops, SMC were very faintly c-kit and -SMA. Under TEM, there were few differentiated SMC and no presumptive ICC. In the less-damaged loops, SMC were faintly c-kit and -SMA and had ultrastructural features intermediate between those of E18.5 and E21.5 controls; ICC were very immature. Conclusions: ICC and SMC differentiation is delayed in gastroschisis with the most damaged loops showing the most incomplete picture. These findings might help in understanding the delayed onset of peristalsis and the variable timecourse of the recover seen in babies affected by gastroschisis.