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Biodegradable collagen scaffolds are used clinically for oral soft tissue augmentation to support wound healing. This study sought to provide a novel ex vivo model for analyzing healing kinetics and gene expression of primary human gingival fibroblasts (hGF) within collagen scaffolds. Sponge type and gel type scaffolds with and without platelet-derived growth factor-BB (PDGF) were assessed in an hGF containing matrix. Morphology was evaluated with scanning electron microscopy, and hGF metabolic activity using MTT. We quantitated the population kinetics within the scaffolds based on cell density and distance from the scaffold border of DiI-labled hGFs over a two-week observation period. Gene expression was evaluated with gene array and qPCR. The sponge type scaffolds showed a porous morphology. Absolute cell number and distance was higher in sponge type scaffolds when compared to gel type scaffolds, in particular during the first week of observation. PDGF incorporated scaffolds increased cell numbers, distance, and formazan formation in the MTT assay. Gene expression dynamics revealed the induction of key genes associated with the generation of oral tissue. DKK1, CYR61, CTGF, TGFBR1 levels were increased and integrin ITGA2 levels were decreased in the sponge type scaffolds compared to the gel type scaffold. The results suggest that this novel model of oral wound healing provides insights into population kinetics and gene expression dynamics of biodegradable scaffolds.

The aim of the present study was to measure the therapeutic effects of bradykinin antagonists on lesion volume and brain swelling induced by cold injury in the parietal cortex of rat and mouse, respectively. Cold lesion was induced by application of a precooled (-78 degrees C) copper cylinder (3 mm diameter) to the intact dura of rat and mouse for 6 and 30 sec, respectively. At 24 h after the injury, the brains were removed and lesion volume was determined by the triphenyltetrazolium chloride method in rats. In the mouse, brain swelling was expressed as percentage increase in weight of the injured hemisphere which is compared to the contralateral side. After a subcutaneous priming dose of 18 microg/kg, a 1-h pretreatment and 24-h posttreatment using osmotic minipumps (300 ng/kg x min) was applied. Hoe140, a bradykinin receptor 2 antagonist, revealed a 19% reduction of lesion volume (p < 0.05) in the rat and a 14% diminution of brain swelling (p < 0.05) in the mouse. In contrast, the bradykinin receptor 1 antagonist, B 9858, had no effect on lesion volume compared to sham treated rats. When B 9858 was given in combination with Hoe140, a significant reduction in lesion volume was seen which was equivalent to and not different from that seen with Hoe140 alone in the rat. We conclude that brain injury after cold lesion is partially mediated by bradykinin and can be successfully treated with B2 antagonists.