Commonly used bowel preparations have significant and different effects upon cell proliferation in the colon: a pilot study

BACKGROUND Markers of crypt cell proliferation are frequently employed in studies of the impact of genetic and exogenous factors on human colonic physiology. Human studies often rely on the assessment of tissue acquired at endoscopy. Modulation of cell proliferation by bowel preparation with oral laxatives may confound the findings of such studies, but there is little data on the impact of commonly used bowel preparations on markers of cell proliferation. METHODS Crypt length, crypt cellularity and crypt cell proliferation were assessed in biopsies acquired after preparation with either Klean-Prep or Picolax. Crypt cell proliferation was assessed by whole-mount mitotic figure count, and by two different immunohistochemical (IHC) labelling methods (Ki-67 and pHH3). Subsequent biopsies were obtained from the same patients without bowel preparation and similarly assessed. Parameters were compared between groups using analysis of variance and paired t-tests. RESULTS There were significant differences in labelling indices (LI) between biopsies taken after Klean-prep and those taken after Picolax preparation, for both Ki67 (p = 0.019) and pHH3 (p = 0.017). A similar trend was seen for whole-mount mitotic figure counts. Suppression or elevation of proliferation parameters by bowel preparation may mask any effect due to an intervention or disease. CONCLUSION Commonly used bowel preparations may have significant and different effects on crypt cell proliferation. This should be taken into account when designing studies and when considering the findings of existing studies.