Epithelial Regeneration After Doxorubicin Arises Primarily From Early Progeny of Active Intestinal Stem Cells

BACKGROUND & AIMS

aISCs (aISCs) are sensitive to acute insults including chemotherapy and irradiation. Regeneration after aISC depletion has primarily been explored in irradiation (IR). However, the cellular origin of epithelial regeneration after doxorubicin (DXR), a common chemotherapeutic, is poorly understood.

METHODS

We monitored DXR's effect on aISCs by enumerating Lgr5-eGFP⁺ and Olfm4⁺ crypts, cleaved caspase-3 (CASP3⁺) immunofluorescence, and time-lapse organoid imaging. Lineage tracing from previously identified regenerative cell populations (Bmi1⁺, Hopx⁺, Dll1⁺, and Defa6⁺) was performed with DXR damage. Lineage tracing from aISCs was compared with lineage tracing from early progeny cells (transit-amplifying cells arising from aISCs 1 day predamage) in the context of DXR and IR. We compared stem cell and DNA damage response (DDR) transcripts in isolated aISCs and early progeny cells 6 and 24 hours after DXR.

RESULTS

Epithelial regeneration after DXR primarily arose from early progeny cells generated by aISCs. Early progeny cells upregulated stem cell gene expression and lacked apoptosis induction (6 hours DXR: 2.5% of CASP3⁺ cells, p<0.0001). aISCs downregulated stem cell gene expression and underwent rapid apoptosis (6 hours DXR: 63.4% of CASP3⁺ cells). There was minimal regenerative contribution from Bmi1⁺, Hopx⁺, Dll1⁺, and Defa6⁺-expressing populations. In homeostasis, 48.4% of early progeny cells were BrdU⁺, and expressed low levels of DDR transcripts.

CONCLUSIONS

We show that DXR effectively depleted aISCs in the small intestine and subsequent epithelial regeneration depended on nonquiescent early progeny cells of aISCs. The chemoresistant phenotype of the early progeny cells may rely on a dampened DDR in contrast to aISCs' robust DDR, which facilitates expeditious apoptosis.

Symposium on intensive care: 3. Upper gastrointestinal bleeding in the intensive care unit

Bleeding from hemorrhagic erosions in the stomach or duodenum of seriously ill patients is associated with a high mortality. While the pathogenesis of such lesions is by no means certain, it is known that they are universal after shock, sepsis or severe burns. Fiberoptic endoscopy has become the most valuable means of diagnosis. This should be preceded by gastric irrigaiton, which usually sufficies to control bleeding caused by acetylsalicylic acid or alcohol, or both. Neutralization of gastric acidity is essential. The histamine HI-receptor antagonist, cimetidine, was used in 27 patients with erosive gastritis, and bleeding ceased in 24. There is a prospect that sugh agents will obviate the necessity of total gastrectomy in the occasional resistant cases in favour of conservative surgery.