Interferon-γ-loaded collagen scaffolds reduce myofibroblast numbers in rat palatal mucosa

Wound contraction and scar formation after cleft palate repair lead to growth impairment of the maxilla and midface. Myofibroblasts play a key role in these processes. The application of an interferon-γ (IFN-γ)-loaded collagen scaffold after surgery might reduce the differentiation of myofibroblasts. In this study, the tissue response to IFN-γ-loaded collagen scaffolds was evaluated after implantation in the palate of rats. Scaffolds, with or without IFN-γ, were implanted submucoperiosteally in the palate of two groups of 25 five-week-old male Wistar rats. Groups of five rats were sacrificed at 1, 2, 4, 8, and 16 weeks post-implantation and processed for histological analyses. On haematoxylin and eosin-stained sections, the cell density and number of giant cells within the scaffolds were determined. Blood vessels, inflammatory cells, and myofibroblasts were detected by immunohistochemistry. The data for cell density, blood vessels, and giant cells were compared with a two-way analysis of variance. The scores for myofibroblasts and inflammation were compared by a rank sum test. A mild and rapidly subsiding inflammatory and foreign body response was found in both groups. Angiogenesis had already begun after 1 week, showed a peak after 4 weeks, and declined thereafter. IFN-γ induced a faster influx of host cells and a major reduction in myofibroblast numbers. The scaffolds might be suitable for future applications in oral surgery.