Fig 1: hPMSC-derived RSPO proteins are necessary for hPO expansion. a, b Concentration of RSPO1 and RSPO3 (expressed in pg/ml) secreted by hPMSC in both MSC standard medium and CC3 medium after seven days of culture. c Confocal microscopy images show representative fluorescent signals from DAPI (405, shown in blue), Vimentin (555, shown in red) and RSPO1 (488, shown in green) of hPMSC isolated from pancreatic digested tissue. Scale bars, 100 μm for 20X objective and 30 μm for 63X objective. d Schematic representation of neutralizing antibodies experiment set up. Created with BioRender.com. e Representative bright-field images of hPO treated or non-treated with neutralizing antibody against RSPO1. Scale bar, 500 μm. f Relative cell viability of hPMSC treated and non-treated with neutralizing antibody against RSPO1. g Relative cell viability of hPO treated and non-treated with neutralizing antibody against RSPO1. Data are means ± SD (n = 3 independent experiments, each performed on samples from five different donors). g A two-sided, unpaired Student’s t-test was used, ** p < 0.01