Figure 6

Analysis of hypertrophic cell morphology in MSC pellets after chondrogenic induction with BMP-2 or BMP-4 gene transfer in comparison to growth plate chondrocytes. Lacunar sizes were measured in the different zones of growth plate cartilage obtained from a four-year-old child, from which a sixth toe was removed. (a) The different cell morphologies and lacunar sizes in the reserve, proliferative, hypertrophic and calcifying zone of growth plate cartilage can be observed. (b) Measurements of the lacunar sizes in the respective zones are shown. Note that the mean values +/- SD represent analyses of size-measurements of 10 lacunae per zone, which were performed on three representative mid-sections per growth plate, and a total of four physes (one digit, two joints) were examined. (c) The GFP-modified aggregates showed no lacunae formation. (d, e) In contrast the BMP-2 and BMP-2 modified aggregates displayed a strong chondrogenic phenotype with formation of large lacunae in the (d) BMP-2 and (e) BMP-4 modified aggregates at day 21 of culture. (f) Analyses of lacunae surface areas in the center and periphery (outer 200 μm area) of the different aggregate types at day 21 of culture. The data represent mean values ± SD from four aggregates per condition and marrow preparation and was performed on six marrow preparations from different patients. Asterisks indicate values that are statistically different (P < 0.05) from marker gene vector-transduced control cultures. Thus both, the BMP-2 and the BMP-4 were significantly larger compared with the non-chondrogenic controls and displayed lacunar sizes comparable with those of the hypertrophic and calcifying zones of growth plate cartilage. Original magnification: 200×; scale bar = 50 μm. BMP = bone morphogenetic protein; GFP = green fluorescent protein; MSC = mesenchymal stem cell; SD = standard deviation.