TIMP1 inhibits Notch signaling-mediated suppression of myeloid differentiation. (A) Hes1 expression in DLL4 stimulated LSK cells in the culture. LSK cells purified from B6 mice were cultured in a medium with indicated stimuli for 5 h. Expression of Hes1 transcripts was determined by qRT-PCR. Symbols depict data from three to five independent experiments with bars showing the mean value ± SD. ** P < 0.01; ns, P > 0.05 (unpaired two-tailed Student’s t test). (B) Expression of Hes1 transcripts in LSK cells sorted from mice at 12 wk after sham surgery (n = 6) or CL&P surgery (n = 6). Symbols represent individual mice; red lines show the mean value. * P < 0.05 (unpaired two-tailed Student’s t test). (C) Dot plot presentation of Notch target gene expression in scRNA-seq datasets of sham or CL&P LSK cells. (D) TIMP1 antagonizes DLL4-mediated suppression of myelopoiesis in vitro. LSK cells sorted from B6 mice were cultured with DLL4 in the presence or absence of TIMP1. CD11b⁺ cells developed in the 5-day culture were analyzed by FACS and shown in dot plots. The right panel shows statistics from six independent cell cultures. Bars depict the mean value ± SD. **** P < 0.0001 (unpaired two-tailed Student’s t test). (E) Treatment scheme and representative FACS plots showing percentages of CD11b⁺ myeloid cells and B cells in the BM of GI254023X-treated mice (n = 9) or vehicle-treated mice (n = 7). Statistic numbers of CD11b⁺ cells and B cells in the BM with the average cell counts ± SD are shown in the bottom right panel. Each dot represents an individual mouse. Data were compiled from two independent experiments. **** P < 0.0001; ns, P > 0.05 (unpaired two-tailed Student’s t test).