DiI labeling does not affect MSC osteogenic gene expression. MSCs were labeled with DiI and cultured in EM or OM for 21 days. Osteocalcin (OC) mRNA expression was measured by real-time RT-PCR and normalized to GAPDH. Unlabeled MSCs were used as controls. Values shown are mean ± SD from cells isolated from a 61-year-old male donor, plated at 3,000/cm2. (JPEG 305 kb