Figure 1.

Heparin μIsland Composition and Growth Factor Sequestration. a) Particles were composed of a PEG-maleimide backbone and MMP-2 cleavable crosslinker with an RGD cell adhesive peptide with or without thiolated heparin. Small fractions of heparin particles (μIslands) were mixed with no-heparin particles to generate growth factor depots. b) Heparin concentration within the particles was matched to mouse skin (Hep_High) and one tenth of mouse skin (Hep_Low). c) To test for PDGF localization around our heparin μislands, we used a well-based assay with heterogenous scaffolds (10% Hep_High) embedded within a collagen-agarose scaffold before introduction of a solution of biotin-labeled PDGF. d) After fixation, fluorescent Streptavidin revealed PDGF localization (red) in the heparin μIslands (green) as early as 1 hour. e) Quantification of fluorescence in the heparin particles across the 48hr time point. Graphs represent mean +/− standard deviation.