Where we stand with human hypertrophic and keloid scar models.

We have yet to create a human scar model that demonstrates the complex nature of hypertrophic scar and keloid formation as well as ways to prevent them despite emerging advances in our understanding of the immune system, the inflammatory response, and proteomic and genomic changes after injury. Despite more complex in vitro models, we fail to explain the fundamental principles to scar formation, and the timeline of their development. The solution to developing the ideal in vitro scar model is one that mimics the heterogeneous cellular and molecular interactions, as well as the evolving structure and function of human skin.