Validation of MSC-BMP2 differentiation in a bone chip. Gene expression of the osteogenic markers Osteopontin (OPN), Bone-sialoprotein (BSP) and Collagen-1 (Col1) was evaluated 3 weeks after seeding using qRT-PCR (a, n = 5, *P < 0.05; Bars indicate standard deviation). The cells were fixed, bone-chips were sectioned using vibratome across the channels and stained for Osteocalcin and BSP (b). Other chips were fixed, whole chips were fluorescently stained against the same osteogenic markers and imaged in × 10 magnification (c). Whole chips were stained for Col1 and the entire chip was imaged using confocal microscopy (d). In other sample, set staining was performed against Osteocalcin (Oc), BSP and Col1 and imaged using confocal microscopy (e)