PURPOSE: Current dermal replacement products perform sub-optimally in complex wound beds, such as those that have been irradiated or those with exposed hardware, mostly as a result of insufficient cell invasion and vascularization. We have previously observed more robust endothelial cell invasion of scaffolds containing a micropatterned matrix of differential collagen stiffness in a murine model when compared to collagen controls. Herein we compare the performance of our micropatterned

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... re hydrogels (MSS) to a widely utilized commercially available dermal replacement product in vitro and in vivo. METHODS: Microspheres composed of 1% type I collagen 50-150um in diameter were created and encased in a 0.3% type I collagen bulk. For our in vitro study, polydimethylsiloxane (PDMS) wells of 4mm diameter and 2mm height were filled with the microsphere scaffolds. 3x2mm Integra® disks were placed inside PDMS wells. Non-microsphere containing 1% and 0.3% collagen scaffolds served as controls. A monolayer of endothelial cells was seeded onto this three-dimensional platform, activated for invasion with 1uM sphingosine-1-phosphate, and cultured for 3 days. The collagen hydrogels were then analyzed using confocal microscopy to quantify cell invasion. For our in vivo study, 8x2mm MSS disks were created, along with 1% and 0.3% collagen controls. 8mm Integra® disks were created, and the unilateral silicone layer was removed. A disk of each type was then implanted subcutaneously in the dorsum of 8-week old wild-type mice. The scaffolds were removed at 7 and 14 days, imaged, and analyzed with ImageJ.