The spatial and temporal quantification of myofibroblasts.

The number and distribution of myofibroblasts in porcine excisional wounds have been measured over a 16-week period by immunoperoxidase labeling of the smooth-muscle antigen in the cytoplasm of the contractile fibroblasts. Changes in the number of myofibroblasts over time correlate with the rate of wound contraction, and the myofibroblasts were distributed throughout the granulation tissue. These findings support the proposal that the contractile fibroblast is the agent of wound contraction. Significantly fewer myofibroblasts are found near the base of the wound and a larger number of myofibroblasts are found in close proximity to inflammatory foci, suggesting a causal relationship between inflammation and the acquisition of contractile properties by the wound fibroblast. There is evidence of a slightly lower percentage of myofibroblasts in areas of rapid fibroblast replication, and the percentage of myofibroblasts does not vary with changes in the tension across a wound. The immunoperoxidase-staining technique permits the identification of individual myofibroblasts by light microscopy and will be a useful tool for further studies of myofibroblast activity and control.