Radiation-induced thrombocytopenia is a common and life-threatening side effect of ionizing radiation (IR) therapy. However, the underlying pathological mechanisms remain unclear. In the present study, irradiation was demonstrated to significantly reduce platelet levels, inhibit megakaryocyte differentiation, and promote the apoptosis of bone marrow (BM) cells. A metabolomics approach and a UHPLC-QTOF MS system were subsequently employed for the comprehensive analysis of serum metabolic profiles of normal and irradiated mice. A total of 66 metabolites were significantly altered, of which 56 were up-regulated and 10 were down-regulated in irradiated mice compared to normal mice on day 11 after irradiation. Pathway analysis revealed that disorders in glycerophospholipid metabolism, nicotinate and nicotinamide metabolism, sphingolipid metabolism, inositol phosphate metabolism, and tryptophan metabolism were involved in radiation-induced thrombocytopenia. In addition, three important differential metabolites, namely L-tryptophan, LysoPC (17:0), and D-sphinganine, which were up-regulated in irradiated mice, significantly induced the apoptosis of K562 cells. L-tryptophan inhibited megakaryocyte differentiation of K562 cells. Finally, serum metabolomics was performed on day 30 (i.e., when the platelet levels in irradiated mice recovered to normal levels). The contents of L-tryptophan, LysoPC (17:0), and D-sphinganine in normal and irradiated mice did not significantly differ on day 30 after irradiation. In conclusion, radiation can cause metabolic disorders, which are highly correlated with the apoptosis of hematopoietic cells and inhibition of megakaryocyte differentiation, ultimately resulting in thrombocytopenia. Further, the metabolites, L-tryptophan, LysoPC (17:0), and D-sphinganine can serve as biomarkers for radiation-induced thrombocytopenia.

Introduction: Radiation-induced thrombocytopenia (RIT) is a serious complication of cancer radiotherapy, for which therapeutic options are limited. This study investigates wedelolactone (WED), a metabolite of a botanical drug, as a potential treatment for RIT.Methods: In vitro experiments were conducted using Meg‐01 and K562 cell lines to evaluate the effects of WED on megakaryocyte differentiation and maturation. Flow cytometry and phalloidin staining were employed to assess the expression of megakaryocyte‐specific markers CD41 and CD61, as well as nuclear polyploidization. A mouse model of RIT was established to assess the efficacy of WED in restoring platelet counts and regulating hematopoiesis. RNA sequencing and western blot analyses were performed to explore the underlying molecular mechanisms.Results: In vitro experiments revealed that WED enhanced megakaryocyte differentiation in a dose‐dependent manner, increasing the expression of lineage‐specific markers CD41 and CD61, and promoting polyploidization and cytoskeletal reorganization. In vivo, WED significantly restored platelet counts in the mouse model of RIT and promoted the production of hematopoietic stem cells (HSCs), megakaryocytes, and reticulated platelets. RNA sequencing and western blot revealed that WED-induced megakaryocyte differentiation involves the regulation of mitochondrial oxidative phosphorylation mediated by the AMPK signaling pathway and activation of the MAPK signaling pathway. Inhibition of mitochondrial oxidative phosphorylation or MAPK signaling suppressed WED‐induced megakaryocyte differentiation, highlighting the central role of these pathways.Discussion: These findings indicate that WED could be a promising therapeutic candidate for RIT, acting through the modulation of oxidative phosphorylation and MAPK signaling pathways to enhance thrombopoiesis.

Stimulating erythropoiesis is essential in the treatment of various types of anemia. Sheng Xue Ning (SXN) is commonly used in China as an iron supplement to treat iron deficiency anemia, renal anemia, and anemia in pregnancy. This research reports a novel effect of SXN in enhancing the proliferation of hematopoietic stem/progenitor cell (HSPC) to promote erythropoiesis in the bone marrow, which is distinct from conventional iron supplements that primarily aid in the maturation of red blood cells. Employing a model of hematopoietic dysfunction induced by X-ray exposure, we evaluated the efficacy of SXN in restoring hematopoietic function. SXN significantly promoted the recovery of peripheral erythroid cells and enhanced the proliferation and differentiation of Lin⁻/c-KIT⁺/Sca-1⁺ HSPC in mice exposed to X-ray irradiation. Our results showed that SXN elevated the expression of stem cell factor (SCF) and activated the SCF/c-KIT/PI3K/AKT signaling pathway, facilitating the proliferation and differentiation of HSPC. In vitro, SXN markedly enhanced the proliferation of bone marrow nucleated cell (BMNC) and the colony-forming capacity of BFU-E, CFU-E, and CFU-GM, while also elevating the expression of proteins involved in the SCF/c-KIT/PI3K/AKT pathway in BMNC. Additionally, SXN enhanced the proliferation and differentiation of mesenchymal stem cell (MSC) and increased SCF secretion. In conclusion, SXN demonstrates the capacity to enhance erythropoiesis by upregulating SCF expression, thereby promoting HSPC proliferation and differentiation via the SCF/c-KIT/PI3K/AKT pathway. SXN may offer a new strategy for improving the activity of HSPC and promoting erythropoiesis in the treatment of hematopoiesis disorders.