Radiation-induced toxicity in rectal epithelial stem cell contributes to acute radiation injury in rectum

Abstract

Background Radiation-induced rectal epithelial damage is a very common side effect of pelvic radiotherapy and often compromise the life quality and treatment outcome in patients with pelvic malignancies. Unlike small bowel and colon, effect of radiation in rectal stem cells has not been explored extensively. Here we demonstrate that Lgr5-positive rectal stem cells are radiosensitive and organoid-based transplantation of rectal stem cells mitigates radiation damage in rectum. Methods C57Bl6 male mice (JAX) at 24 h were exposed to pelvic irradiation (PIR) to determine the radiation effect in pelvic epithelium. Effect of PIR on Lgr5-positive rectal stem cells (RSCs) was determined in Lgr5-EGFP-Cre-ERT2 mice exposed to PIR. Effect of PIR or clinically relevant fractionated PIR on regenerative response of Lgr5-positive RSCs was examined by lineage tracing assay using Lgr5-eGFP-IRES-CreERT2; Rosa26-CAG-tdTomato mice with tamoxifen administration to activate Cre recombinase and thereby marking the ISC and their respective progeny. Ex vivo three-dimensional organoid cultures were developed from Lgr5-EGFP-Cre-ERT2 mice. Organoid growth was determined by quantifying the budding crypt/total crypt ratio. Organoids from Lgr5-EGFP-ires-CreERT2-TdT mice were transplanted in C57Bl6 male mice exposed to PIR. Engraftment and repopulation of Lgr5-positive RSCs were determined after tamoxifen administration to activate Cre recombinase in recipient mice. Statistical analysis was performed using Log-rank (Mantel-Cox) test and paired two-tail t test. Result Exposure to pelvic irradiation significantly damaged rectal epithelium with the loss of Lgr5+ve rectal stem cells. Radiosensitivity of rectal epithelium was also observed with exposure to clinically relevant fractionated pelvic irradiation. Regenerative capacity of Lgr5+ve rectal stem cells was compromised in response to fractionated pelvic irradiation. Ex vivo organoid study demonstrated that Lgr5+ve rectal stem cells are sensitive to both single and fractionated radiation. Organoid-based transplantation of Lgr5+ve rectal stem cells promotes repair and regeneration of rectal epithelium. Conclusion Lgr5-positive rectal stem cells are radiosensitive and contribute to radiation-induced rectal epithelial toxicity. Transplantation of Lgr5-positive rectal stem cells mitigates radiation-induced rectal injury and promotes repair and regeneration process in rectum.

Preclinical investigation of patient-derived cervical cancer organoids for precision medicine

“…Although there have been few reports of radiation sensitivity testing for cancer organoids including rectal, colon, and nasopharyngeal cancer [ 18 19 20 21 ], to the author’s knowledge, this is the first study to establish the preclinical in vitro model to predict radiotherapy response using cervical cancer organoids. Optimizing radiation sensitivity through these PDOs is an essential strategy to increase the long-term survival of cervical cancer.…”

Expression of Stem Cell Markers in High-LET Space Radiation-Induced Intestinal Tumors in Apc1638N/+ Mouse Intestine

“…Notably, LGR5 functions as a tumor suppressor during colon cancer progression [20][21][22]. IR exposure is known to reduce the number of LGR5-positive cells in the intestine owing to the higher radiosensitivity of these cells [23]. Additionally, LGR5 expressing cells readily undergo senescence after sub-lethal high-LET radiation exposure [8].…”

Claudin-7 is essential for the maintenance of colonic stem cell homoeostasis via the modulation of Wnt/Notch signalling

“…Mouse intestinal crypts were isolated as previously described with minor modifications [ 49 ]. Briefly, colonic crypt isolation and organoid culture were conducted using the IntestiCult system (STEMCELL Technologies), according to the manufacturer’s instructions.…”