Anyone who has ever bitten his tongue and skinned a knee can attest to the fact that wounds in the oral cavity "just seem to heal a lot better," says Luisa DiPietro, director of the Center for Wound Repair and Regeneration at the University of Illinois, Chicago. She and her colleagues have published several papers demonstrating differences in oral and skin wound healing, related to inflammatory and antigenic responses at the cellular level. In a recent investigation, DiPietro and her team dug into the transcriptomes of both kinds of wounds by using a comparative microarray analysis in mice. The researchers published their results in BMC Genomics in August.
"The oral mucosa, in contrast to the skin, has a much more limited response to the injury," DiPietro says. "There's less transcriptional activity and it heals much more quickly."
Indeed, her team identified 1,479 probe sets that were significantly differentially expressed in skin wounds and only 502 in mucosal wounds over the course of 10 days, when compared with unwounded matched control tissue. In subsequent in vitro analyses, DiPietro's team found that skin epithelial cells contain more pro-inflammatory cytokines post-injury, even "when they're divorced from the environment. ... Our data very clearly shows that the differences go well beyond environmental."
Her group is currently working to decipher the basis for these site-specific differences in wound-healing activities.
"Whether they be genetic, whether it involves some differential transcriptional regulation, some differential mRNA stability ... there are many possibilities, [and] those are the things that we're interested in now," she says.
In the end, DiPietro is hopeful that genetic insights gleaned from these investigations — and future studies in humans — could affect treatment in the clinic. "We're certainly interested in looking at clusters of genes that have, for example, similar transcriptional regulation, because those might be things that you can target," DiPietro says. "When you change wound-healing to move towards the ideal, maybe a refined target will be a better target."