Figure 6.

In vitro release of GDF-5 from recombinant GDF-5-coated collagen matrices over time. (a) The table represents: (1) the time point at which the highest GDF-5 protein release from each of the four collagen matrices, coated with recombinant GDF-5, was observed (peak in the release); (2) ELISA quantifications of the GDF-5 released in phase I and expressed as percent of the total protein release for the entire test period of 13 days (taken as 100%); (3) ELISA quantifications of the GDF-5 released in phase II and expressed as in (2). The peak of the protein release marks the end of phase I whereas phase II spans the time period immediately after the peak in the release until day 13. Means ± SD from three independent experiments and significant differences (P < 0.05) between the experimental groups are shown. Significance was indicated with the following symbols: # denotes significantly higher than NCM, $ denotes significantly higher than CCM, Ϯ denotes significantly higher than DADM, and ǂ denotes significantly higher than HADM. (b) ELISAs were used to quantify the amounts of GDF-5 in conditioned PBS solution collected from the matrices at the indicated time intervals over a 13-day period. Data represent means ± SD from three independent experiments. Significant differences between experimental groups, *** P < 0.001, ** P < 0.01, * P < 0.05. (c) Three-dimensional graph of the data present in (b) for better visualization of the release kinetics.