Prior to RNA isolation, the L3 lumbar vertebral body of each frozen sample was excised from the intact vertebral segment using a Dremel rotary saw. Samples were prepared for RNA extraction by first pulverizing each bone sample individually using a Freezer Mill (Spex CertiPrep, NJ). RNA was extracted from the powdered bone samples using the RiboPure RNA isolation kit (Ambion Inc., Austin, TX) according to the manufacturer’s protocol. RNA samples were quantified by spectroscopy (NanoDrop Technologies, Wilmington DE) and visualized for purity and integrity using the Agilent 2100 Bioanalyzer (Santa Clara, CA) prior to gene array analysis.
