Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina, United States of America.
PLoS One. 2012;7(12):e51310. doi: 10.1371/journal.pone.0051310. Epub 2012 Dec 7.
In vivo studies of high dose radiation-induced crypt and intestinal stem cell (ISC) loss and subsequent regeneration are typically restricted to 5-8 days after radiation due to high mortality and immune failure. This study aimed to develop murine radiation models of complete crypt loss that permit longer-term studies of ISC and crypt regeneration, repair and normalization of the intestinal epithelium.
In C57Bl/6J mice, a predetermined small intestinal segment was exteriorized and exposed to 14 Gy-radiation, while a lead shield protected the rest of the body from radiation. Sham controls had segment exteriorization but no radiation. Results were compared to C57Bl/6J mice given 14 Gy-abdominal radiation. Effects of elemental liquid diet feeding from the day prior to radiation until day 7 post-radiation were assessed in both models. Body weight and a custom-developed health score was assessed every day until day 21 post-radiation. Intestine was assessed histologically.
At day 3 after segment radiation, complete loss of crypts occurred in the targeted segment, while adjacent and remaining intestine in segment-radiated mice, and entire intestine of sham controls, showed no detectable epithelial damage. Liquid diet feeding was required for survival of mice after segment radiation. Liquid diet significantly improved survival, body weight recovery and normalization of intestinal epithelium after abdominal radiation. Mice given segment radiation combined with liquid diet feeding showed minimal body weight loss, increased food intake and enhanced health score.
The segment radiation method provides a useful model to study ISC/crypt loss and long-term crypt regeneration and epithelial repair, and may be valuable for future application to ISC transplantation or to genetic mutants that would not otherwise survive radiation doses that lead to complete crypt loss. Liquid diet is a simple intervention that improves survival and facilitates long-term studies of intestine in mice after high dose abdominal or segment radiation.
由于高死亡率和免疫功能衰竭，体内高剂量辐射诱导隐窝和肠干细胞（ISC）丢失及随后再生的研究通常限制在辐射后 5-8 天内。本研究旨在开发完全丧失隐窝的小鼠辐射模型，以允许对 ISC 和隐窝再生、修复以及肠上皮的正常化进行更长期的研究。
在 C57Bl/6J 小鼠中，将预定的小肠段外展并暴露于 14Gy 辐射下，同时使用铅屏蔽保护身体的其余部分免受辐射。假手术对照仅进行外展但不进行辐射。将结果与接受 14Gy 腹部辐射的 C57Bl/6J 小鼠进行比较。在这两种模型中，评估了从辐射前一天到辐射后 7 天进行元素液体饮食喂养的效果。在辐射后 21 天内，每天评估体重和自行开发的健康评分。对肠组织进行组织学评估。
在辐射后第 3 天，靶段的隐窝完全丧失，而相邻和剩余的肠段辐射的小鼠以及假手术对照的整个肠段均未检测到上皮损伤。液体饮食是辐射后小鼠存活所必需的。液体饮食显著提高了腹部辐射后的存活率、体重恢复和肠上皮的正常化。接受段辐射加液体饮食的小鼠体重减轻最小、食物摄入量增加且健康评分提高。
段辐射方法提供了一种有用的模型，可用于研究 ISC/隐窝丢失和长期隐窝再生以及上皮修复，并且可能对未来的 ISC 移植或无法在导致完全隐窝丢失的辐射剂量下存活的遗传突变体应用具有价值。液体饮食是一种简单的干预措施，可提高高剂量腹部或段辐射后小鼠的存活率并促进长期肠研究。
