Reducing TGF-β1 cooperated with StemRegenin 1 promoted the expansion ex vivo of cord blood CD34+ cells by inhibiting AhR signalling.

OBJECTIVE As an inhibitor of the AhR signalling pathway, StemRegenin 1 (SR1) not only promotes the expansion of CD34+ cells but also increases CD34- cell numbers. These CD34- cells influenced the ex vivo expansion of CD34+ cells. In this work, the effects of periodically removing CD34- cells combined with SR1 addition on the ex vivo expansion and biological functions of HSCs were investigated. MATERIALS AND METHODS CD34- cells were removed periodically with SR1 addition to investigate cell subpopulations, cell expansion, biological functions, expanded cell division mode and supernatant TGF-β1 contents. RESULTS After 10-day culture, the expansion of CD34+ cells in the CD34- cell removal plus SR1 group was significantly higher than that in the control group and the SR1 group. Moreover, periodically removing CD34- cells with SR1 addition improved the biological function of expanded CD34+ cells and significantly increased the percentage of self-renewal symmetric division of CD34+ cells. In addition, the concentration of total TGF-β1 and activated TGF-β1 in the supernatant was significantly lower than those in the control group and the SR1 group. RT-qPCR results showed that the periodic removal of CD34- cells with cooperation from SR1 further reduced the expression of AhR-related genes. CONCLUSIONS Periodic removal of CD34- cells plus cooperation with SR1 improved the expansion of CD34+ cells, maintained better biological function of expanded CD34+ cells and reduced the TGF-β1 contents by downregulating AhR signalling.