Keratinocytes cover both the skin and some oral mucosa, but the morphology of each tissue and the behavior of the keratinocytes from these two sites are different. One significant dissimilarity between the two sites is the response to injury. Oral mucosal wounds heal faster and with less inflammation than equivalent cutaneous wounds. We hypothesized that oral and skin keratinocytes might have intrinsic differences at baseline as well as in the response to injury, and that such differences would be reflected in gene expression profiles.

Studies in the field of wound healing have utilized a variety of different housekeeping genes for RT-qPCR analysis. However, nearly all of these studies assume that the selected normalization gene is stably expressed throughout the course of the repair process. The purpose of our current investigation was to identify the most stable housekeeping genes for studying gene expression in mouse wound healing using RT-qPCR. To identify which housekeeping genes are optimal for studying gene expression in wound healing, we examined all articles published in Wound Repair and Regeneration that cited RT-qPCR during the period of Jan/Feb 2008 until July/August2009. We determined that ACTIN, GAPDH, 18S and β2M were the most frequently used housekeeping genes in human, mouse, and pig studies. We also investigated nine commonly used housekeeping genes that are not generally used in wound healing models: GUS, TBP, RPLP2, ATP5B, SDHA, UBC, CANX, CYC1, and YWHAZ. We observed that wounded and unwounded tissues have contrasting housekeeping gene expression stability. The results demonstrate that commonly used housekeeping genes must be validated as accurate normalizing genes for each individual experimental condition.

Inflammation in wounds is a highly ordered process that significantly impacts wound healing outcomes. Several pieces of evidence point to a positive role for leukocytes in the stimulation of the proliferative phase of healing. In particular, macrophages appear to support healing through the generation of growth factors that promote cell proliferation and protein synthesis. While much remains to be learned, the accumulated information suggests that a carefully balanced inflammatory response is needed to provide maximal support for both infection prevention and optimal healing outcomes following injury. Wounds in the oral mucosa seem to benefit from a minimized inflammatory response that is supportive of repair.

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