Figure 2.

Impossible to make a “builder” drug for wound healing from a single molecule. When tissue is wounded, multiple tissue components have been damaged. To repair and re-build the damaged tissue, a healthy body initiates a healing program inside the wound involving multiple cell types, new ECMs, and cell type-specific soluble factors. In contrast, a similar healing program cannot be launched in chronic wounds in humans with various compromised health conditions, and no single factor has the capacity of replacing the healing program. Any single factor can only directly affect one of the many coordinated events, as shown, during wound healing. For instance, the addition of an angiogenic factor activates angiogenesis, but it has little direct effect on the deposition of ECMs by dermal fibroblasts nor keratinocyte migration to re-epithelialize the wound. Similarly, PDGF-BB selectively activates dermal fibroblasts, but nether keratinocytes nor endothelial cells express PDGF receptors. “X” means “no” and “?” means “may be”.