FIG. 4.

Differentiation of MC3T3 (A) and D1 cells (B) in three-dimensional culture. Cells were encapsulated in linear arginine-glycine-aspartate (RGD)-modified alginate (diamond) (degree of substitution [DS] 1, equivalent to 1 mole of RGD per mole of alginate and total linear RGD density of 6.25 mg RGD/g alginate) or unmodified alginate (open square). (A) MC3T3 osteocalcin secretion (normalized to DNA) assessed at days 3, 10, and 21 of culture. (B) D1 osteocalcin secretion and osteocalcin messenger RNA levels (C) at days 3, 10, and 21 of culture. Cells were cultured at 37^°C and 5% carbon dioxide for 21 days, and medium was supplemented with 50 μg/mL ascorbic acid only for osteogenic induction of MC3T3s and 50μg/mL ascorbic acid and 10mM β-glycerophosphate for D1 cells. Values represent means and standard deviations (n = 4). ^*p < 0.05 between noted conditions (unmodified vs DS 2 linear RGD) at the same time-point.