Distribution, development and proliferation of interstitial cells of Cajal in murine colon: an immunohistochemical study from neonatal to adult life.

This paper aimed at investigating the alterations in interstitial cells of Cajal (ICC) in the proximal, middle and distal colon of mice from 0-day to 56-day post-partum (P0-P56) by immunohistochemistry. The Kit(+) ICC, which situated around myenteric nerve plexus (ICC-MY) were prominent at birth, meanwhile those cells within the smooth muscle layers (ICC-IM) and in the connective tissue beneath serosa (ICC-SS) began to appear. ICC-SM, which located at the submucosal border of circular muscle layer emerged at P6 in the proximal colon and subsequently in the distal colon at P8, and ICC in the oral side of colon revealed an earlier development in morphology and a higher density than that in the anal side. The density of ICC altered obviously during postnatal period, and the estimated total amount of ICC increased approximately 30 folds at P56 than that at P0. Some Kit(+)/Ki67(+) and Kit(+)/BrdU(+) cells were observed in ICC-MY, ICC-IM and ICC-SS, but not in ICC-SM from P0 to P24. Our result indicates a proximal to distal and transmural gradient development of ICC in the postnatal colon along with a dramatic increase of ICC cell number from neonatal to adult life, and an age-dependent proliferation of ICC is also involved.

Time-specific blockade of PDGFR with Imatinib (Glivec®) causes cataract and disruption of lens fiber cells in neonatal mice.

This study aimed at investigating the response of lens epithelial cells in postnatal mice to Imatinib (Glivec®, a potent inhibitor of platelet-derived growth factor receptor (PDGFR)) treatment. Mouse eyes were sampled 10 days after administration of Imatinib (0.5 mg·g(-1)·day(-1)) for 3 days, at either 7, 14, or 21 days postpartum. Structural changes of lens were revealed by routine H.E. staining. Levels of proliferation and apoptosis were revealed by BrdU incorporation and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, respectively, and immunofluorescent staining with anti-PDGFRα antibody was carried out on the sections of eyeball. PDGFRα and p-PDGFRαprotein levels were evaluated by Western blot. Our results indicated that administration of Imatinib led to blockade of PDGFR signaling. Formation of cataracts was found only in those mice where treatment started from 7 days postpartum (P7), but was not observed in those samples from P14 nor P21. Fiber cells were disorganized in cataract lens core as observed histologically, and migration of epithelial cells was also inhibited. No apoptosis was detected with the TUNEL method. Our results indicated blockade of PDGFR at the neonatal stage (P7) would lead to cataracts and lens fiber cells disorganization, suggesting that PDGFR signaling plays a time-specific and crucial role in the postnatal development of lens in the mouse, and also may provide a new approach to produce a congenital cataract animal model.

Postnatal development of interstitial cells of Cajal in mouse colon in response to Kit signal blockade with Imatinib (Glivec).

This study investigated the response of interstitial cells of Cajal (ICC) in postnatal mouse colon to treatment with Imatinib (Glivec), a potent inhibitor of Kit receptor). ICC were revealed by immunofluorescent staining on frozen cross-sections and whole-mount preparations by anti-Kit and DOG1 antibodies. Kit and p-Kit protein were also evaluated by Western blot. After administration of Imatinib for 4 days beginning at 8 days post-partum (P8), the mean density of Kit+ ICC, which were localized around the myenteric nerve plexus (ICC-MY), within smooth muscle layers (ICC-IM) and in the connective tissue beneath the serosa (ICC-SS), was dramatically decreased to about 50% when compared with controls, but those Kit+ cells located at the submucosal border of circular smooth muscle layer (ICC-SM) seemed to be unchanged in both cell number and morphology. A small number of DOG1+/Kit(-) cells appeared during Imatinib administration. However, these Kit+ ICC were not changed in mice even after 12 days of Imatinib treatment from P24. When Imatinib was discontinued, the number of ICC recovered to normal within 4 days. Our results indicate that the postnatal development of ICC in the mouse colon is Kit dependent, but ICC-SM are unlikely, and the Kit dependence of ICC development is also age-dependent.

Immunohistochemical study of CD44 immunopositive cells in the muscular layers of the gastrointestinal tract in adult guinea pigs and mice.

This study investigates whether CD44 immunopositive cells truly correspond to the interstitial cells of Cajal (ICCs) in the muscular layers of the gastrointestinal tract in guinea pigs and Balb/c mice using immunohistochemistry with antibodies directed against CD44, Kit, vimentin and neurofilament 200 (NF200). All the sub-groups of ICCs were immunopositive for the anti-Kit antibody in the muscular layers of stomach, small intestine and colon in both cross sections and whole-mount preparations. Kit/CD44/vimentin triple immunolabeling showed that all the ICCs in different segments and muscular layers of the digestive tract were CD44, Kit and vimentin immunopositive. Kit/CD44/NF200 triple immunolabeling revealed that neither enteric nerves nor other major cells were CD44 immunopositive in the muscular layers, apart from the ICCs. CD44 and Kit were co-localized in the same group of cells, apart from a very small number (0.6%) of CD44 immunopositive cells that were not Kit immunopositive. Our results indicate that these CD44 immunopositive cells truly correspond to ICCs, thus immunolocalisation of CD44 can be used as a special marker, in addition to Kit, to identify ICCs in the digestive tract in adult guinea pigs and mice.

Apoptosis of interstitial cells of Cajal, smooth muscle cells, and enteric neurons induced by intestinal ischemia and reperfusion injury in adult guinea pigs.

This study aimed at evaluating whether apoptosis of interstitial cells of Cajal (ICC), smooth muscle cells (SMC), and enteric neurons was involved in a guinea pig model of intestinal ischemia and reperfusion injury. The small intestinal segments were resected at either 6 (I60/R6h) and 12 h (I60/R12h) or 7 (I60/R7d) to 14 (I60/R14d) days after 60 min intestinal ischemia in the adult guinea pigs and studied by immunohistochemistry with anti-Kit, 5-bromo-2'-deoxyuridine (BrdU), alpha-smooth muscle actin, vimentin, and beta-tublin III antibodies. Also, apoptosis was tested by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method. In the I60/R12h injury, there was a approximately 50% decrease of Kit+ cells in cell numbers at the level of myenteric plexus and a number of Kit-/vimentin-positive cells were labeled by TUNEL. Also, a few SMC and enteric neurons were TUNEL positive. The Kit+ ICC recovered to normal and a number of Kit-/BrdU-double-positive cells were observed in the I60/R14d group. Our results indicated that the intestinal I/R injury could lead to apoptosis of ICC, SMC, and enteric neurons which may contribute to the gastrointestinal motility disorders, and proliferation was involved in the recovery of ICC.