50 ml of LEC-conditioned was collected from five 10-cm dishes of cultured LECs and filtered through a 0.22μm pore membrane as mentioned above. LEC-conditioned media was further concentrated into 500uls using the
Protein-Concentrate Kit (Millipore) according to the manufacture’s instruction. Protein concentration was then measured by the
BCA protein assay (Thermo Fisher). Experiments were repeated three times and three biological samples were submitted to Northwestern Proteomics Core for untargeted quantitative proteomics analyses by Label-free Quantitative Proteomics: Briefly, samples were analyzed using an
UltiMate™ 3000 RSLCnano system (ThemoFisher Scientific, CA) that is coupled with electrospray ionization (ESI) to a linear ion trap (LTQ) Orbitrap mass spectrometer (
iLTQ-Orbitrap, ThermoFisher, CA). The resulting raw mass spectra from all three replicates were analyzed by the MaxQuant search engine (version 1.6.0.16) using UniprotKB human database with the allowance of up to 2 missed cleavages and precursor mass tolerance of 20 p.p.m. The secretome was acquired using software Scaffold 4 and annotated using Gene Ontology (GO), which assigns putative cellular compartmentalization, biological process and molecular functions.
Liu X., De la Cruz E., Gu X., Balint L., Oxendine-Burns M., Terrones T., Ma W., Kuo H.H., Lantz C., Bansal T., Thorp E., Burridge P., Jakus Z., Herz J., Cleaver O., Torres M, & Oliver G. (2020). Lymphoangiocrine signals promote cardiac growth and repair. Nature, 588(7839), 705-711.