OBJECTIVESlow transit constipation (STC) is a colonic motor disorder whose etiology remains unclear. Recent studies have demonstrated a crucial role for interstitial cells of Cajal (ICC) in regulation of intestinal motility. The aim of this study was to examine the distribution of ICC within the normal sigmoid colon and STC patients.

METHODSTwelve patients with STC and eight age-matched controls were studied. ICC were identified with a monoclonal antibody to c-kit by an indirect immunofluorescence method. Immunostained tissues were examined with a laser scanning confocal microscope and the area occupied by ICC was calculated with image analysis software.

RESULTSICC were located in the external muscle layers including longitudinal muscle (LM), myenteric plexus (MP), circular muscle (CM) and submucosal border (SMB). Two types of Kit-positive ICC were observed: bipolar cells characterized by one or two long processes, and multipolar cells with long stellate processes extending in various directions. A higher percentage of ICC was present in the MP regions and CM layers compared with the SMB and LM layers. Tissues from STC patients showed considerably decreased in number of ICC located in the four regions (ICC-LM, ICC-MP, ICC-CM, ICC-SMP), especially for ICC-SMP, almost completely disappeared.

CONCLUSIONDecreased c-kit + ICC in number may play an important role in the pathophysiology of STC. It remains to be determined whether loss of ICC is primary or secondary to another lesion.