Endogenous Hydrogen Sulphide Promotes the Ex Vivo Expansion of Haematopoietic Stem Cells by Regulating the Activation of the <scp>JAK2</scp>/<scp>STAT3</scp> Pathway

Haematopoietic stem cell transplantation (HSCT) is one of the key strategies for treating various haematologic malignancies. Although there are haematopoietic stem cells (HSCs) in umbilical cord blood (UCB), the number is limited. Thus, the purpose of this work was to investigate if endogenous hydrogen sulphide (H₂S) could encourage the ex vivo expansion of HSCs produced from UCB (UCB-HSCs). The CD34⁺ and CD34⁺CD38^- cells were enriched and separated by immunomagnetic beads. UCB-HSCs were treated with overexpression plasmids of β-synthase (CBS), cystathionine γ-lyase (CSE), 3-mercaptopyruvate sulphurtransferase (MPST) and/or stimulated with AG490 (JAK2/STAT3 inhibitor) for 4, 7 or 10 days, respectively. The content of H₂S in cells was detected using its assay kit. The proportion and quantity of CD34⁺, CD34⁺CD38^- and CXCR4⁺CD34⁺ cells as well as the ALDH1A1⁺CD34⁺ cells in CD34⁺ cells were detected by flow cytometry. qPCR was used to detect the expression of CD34, CXCR4 and ALDH1A1 in CD34⁺ cells. Western blot was used to detect the activation of the JAK2/STAT3 pathway in CD34⁺ cells. The results showed that endogenous H₂S enhanced the ex vivo expansion of CD34⁺ and CD34⁺CD38^- cells, upregulated the expression of CXCR4 and ALDH1A1 during ex vivo expansion of HSCs, and promoted the JAK2/STAT3 pathway in CD34⁺ cells. However, the aforementioned effects of endogenous H₂S were partially reversed by AG490. In conclusion, endogenous H₂S promotes the activation of the JAK2/STAT3 pathway to facilitate the ex vivo expansion of UCB-HSCs.