Different Effects of Leukotriene B4 Receptors on the Proliferation of Mesenchymal Stem Cells

We investigated whether leukotriene B-4(LTB4) and its receptor play important roles in the proliferation of umbilical cord blood derived mesenchymal stem cells(UMSCs). Although it was previously reported that LTB4 induced tumor and stem cell proliferation, LTB4 did not enhance proliferation of the UMSCs. However, the two LTB4 receptors appeared to play opposite roles in the proliferation of UMSCs. The blocking of BLT1 by U-75302 enhanced proliferation of the UMSCs. By contrast, blocking of BLT2 by LY255283 inhibited proliferation of the UMSCs. Also, U-75302 up regulated and LY255283 down regulated the p38 and p44/42 MAPK activation. In conclusion, LTB4 receptors oppositely regulate proliferation of the UMSCs through the p38 and p44/42 MAPK pathways. The LTB4 receptor antagonists were identified to be factor having an effect on the proliferation of UMSCs. The results of this study suggest that the LTB4 receptor signaling pathway might be a novel target for proliferation of the UMSCs.