Ginseng extract and total ginsenosides protect the function of hematopoietic stem cells by activating the Notch and...

Panax ginseng C.A. Meyer (ginseng), a traditional Chinese medicine, is famous for "Qi-tonifying" effect and widely used for healthcare and therapeutic effects in China. Modern pharmacology showed that Ginseng had a potential impact on hematopoietic stem cells (HSCs) that promote the regeneration of all blood cells in the bone marrow. The "Qi-tonifying" effect of ginseng might have close correlation with hematopoietic function. However, the protective effect of ginseng on HSCs has been rarely studied.

To elucidate the difference of chemical composition and the effects of ginseng extract (GE), total ginsenosides (TG) and total polysaccharides (TP) on HSCs of cyclophosphamide (CYP)-induced mice.

The ginsenosides, monosaccharide and molecular distribution of GE, TG, and TP were detected. We established the mouse myelosuppression model induced by CYP. Eight ginsenosides in mice plasma were detected with high-performance liquid chromatography-mass spectrometer (MS)/MS in GE and TG group. Blood cell parameters (red blood cell, hemoglobin, reticulocyte, platelet, white blood cell, neutrophil, and lymphocyte) of plasma, oxidative stress indicators (superoxide dismutase, catalase, glutathione peroxidase, lactate dehydrogenase, malondialdehyde, and myeloperoxidase) of liver, cell differentiation marker (CD33, and GR-1) and colony forming of HSCs were detected. Ribonucleic acid (RNA)-sequencing analysis was performed on purified HSCs to find differentially expressed genes (DEGs). And the expression of DEGs was verified by quantitative polymerase chain reaction (qPCR), western blot, and immunohistochemical (IHC).

Our results showed that 24 and 34 ginsenosides were detected in the GE and TG, and the total sugar content was 72.28 %, 4.68 %, and 89.79 % in GE, TG and TP, respectively. The weight-average molar mass/number-average molar mass (Mw/Mn) values of GE and TP were 2.96 and 1.23. TP showed homogeneous polysaccharide. The results of animal experiments showed that Rb1, Rc, Rb2, Rb3, and Rd of mouse serum in TG group was 22.91, 11.64, 10.73, 9.36, and 8.61 times in GE group, respectively. GE, TG and TP obviously elevated the numbers of blood cells, and improved oxidative stress indicator of liver. The results of RNA-sequencing analysis showed that DEGs in GE, TG and TP groups were primarily focused on signaling pathways related to HSCs. GE and TG obviously promoted the expression of Notch1, Notch2 and Jag1, and inhibited the expression of Hes1 of HSCs in model mice via activating Notch signal pathway. Meanwhile, GE and TG also obviously promoted the expression of Wnt7b, Wnt10b, and Fzd6 of HSCs by activating Wnt signal pathway. However, TP hardly activated the expression of these genes in Notch and Wnt signal pathways. Moreover, TG significantly increased the expression of CD33, CD38, CD14, CD4, CD19 and Gp1bα, and GE remarkably increased the expressions of CD34, CD14, CD4, and Gp1bα. GE and TG significantly increased the Gr-1^hi and decreased the Gr-1^neg. However, TP played less role in HSCs.

This study found that TG and GE showed a strong protection on HSCs in model mice induced by CYP via activating the Notch and Wnt signal pathways, however, TP could not activate HSCs. Therefore, we think that ginsenosides from GE and TG are important chemical components in protecting the function of HSCs by activating the Notch and Wnt signal pathways.