library_construction_protocol: Total RNA from BM-MSCs was extracted using the RNeasy Mini Kit (Qiagen Iberia, Madrid, Spain), according to the manufacturer's protocol. RNA concentration was quantified spectrophotometrically (Nanodrop ND-1000, Wilmington, DE), and its quality and integrity assessed by capillary electrophoresis on an Agilent 2100 Bioanalyzer (Agilent Technologies. Spain). Barcoded cDNA libraries were prepared from poly(A) enriched mRNA using NebNext Ultra Directional RNA Library Prep Kit (New England Biolabs, Spain). Pooled libraries were sequenced on an Illumina NextSeq 500 instrument to generate on average 32.9 million single-end reads of 76 bp length. To avoid a batch effect bias, all samples were run simultaneously twice, and results merged.