Expression of myofibroblasts and identification of angiotensin receptors in capsular contracture disease around mammary implants

Abstract

Capsular contracture is a physically and psychologically debilitating disease characterised by fibrosis and contraction of the breast capsule in women with implants. There is evidence that Angiotensin-II (Ang-II) is implicated in pathological wound healing and that blockers of Ang-II may prevent fibrosis.

Capsules from 12 breasts excised from eight patients undergoing surgery for capsular contracture in the Department of Plastic Surgery at Royal Preston Hospital were harvested. Tissue was dissociated into myofibroblasts using collagenase and cultured to determine growth patterns. Expressions of myofibroblasts and Ang-II receptors (AT1 and AT2) within breast capsule tissue were also investigated using immunohistochemistry.

The results show that myofibroblasts were present in all capsules (n=12). Ang-II receptors were present in 50% (n=6) of capsules (paraffin and cryostat sections). However, in the cryostat-only group, staining was positive in 100% (n=5) of capsules. Expressions of these receptors were also co-localised with α-sma uptake demonstrating the key components of the Renin Angiotensin System (RAS) are present within breast capsule myofibroblasts. Interestingly, a higher expression and wider distribution of AT2 receptors were noted compared with AT1 receptors.

This study has identified the presence of myofibroblasts in breast capsule tissue and has demonstrated that they are amenable to culture successfully. Moreover, these myofibroblasts contain both AT1 and AT2 receptors. Further experiments are required to study the role of blocking the AT1 and AT2 receptor excitation-contraction coupling process of the myofibroblast. This study may provide the basis for a safe and cheap therapeutic strategy with which to modify capsular contracture.