Angelica sinensis polysaccharides ameliorate 5-FU-induced stress anemia via promoting extramedullary erythroblastic island central macrophage-mediated erythroid differentiation.

Background: Chronic anemia, especially chemotherapy-induced anemia, is a common and intractable symptom. Puzzlingly, the conventional anemic treatment may lead to various side effects, and the mechanism of stress anemia remains unclear.

Methods: Here, peripheral blood, histopathological and transmission electron microscopical examination, colony forming test, flow cytometry, and qRT-PCR assay were used to investigate the effects of Angelia sinensis polysaccharide (ASP), one main active ingredient of Chinese herb medicine Angelica sinensis, on ameliorating 5-fluorouracil (5-FU)-induced stress anemia.

Results: We found that intraperitoneal injection to a C57BL/6J mouse ASP 100 mg/kg per day for consecutive 10 days or 14 days, remarkably accelerated the recovery of RBC, hemoglobin, and hematocrit in blood. ASP alleviated 5-FU-caused impairment of bone marrow cell and BFU-E enumeration. Meanwhile, ASP antagonized 5-FU promoting extramedullary erythropoiesis in the spleen, inducing splenomegaly due to stress erythroblastic islands, and occurrence of megakaryocytes and hematopoietic precursors in splenic colonies. ASP increased splenic stress BFU-E enumeration, driving BFU-E differentiation towards Pro-E and end-stage erythroblasts. Furthermore, ASP increased the number of F4/80VCAM-1 splenic erythroblastic island central macrophages, upregulating genetic expression of EPOR, Emp, VCAM-1, Hmox-1, Trf, TfR1, Fpn1, Spi-C, DNase2a, Tim4, MertK, and Klf1 in splenocytes.

Conclusions: Our findings indicate that the possible mechanism of chemotherapy-induced anemia is related to stress erythroid maturation arrest. Whereas, ASP may promote stress erythroid differentiation via elevated EPO sensitivity in extramedullary hematopoietic organs and enhanced macrophage-mediated adhesion, iron homeostasis and transfer, and nuclear engulfment, which may represent a promising therapeutic strategy.