Occurrence and activity of myofibroblasts in human capsular tissue surrounding mammary implants.

Capsular tissue obtained from a series of 16 patients with silicone mammary implants was exposed in vitro to smooth-muscle stimulants and relaxants. Capsule relaxation was produced in 75 percent of the patients. The most active antagonists were papaverine and veratrine. Capsule contracture was produced in 69 percent of the patients. The most active agonists were histamine and epinephrine. Myofibroblasts were identified in several capsules. These data support the hypothesis that the myofibroblasts is a probable cause of capsular contracture.