Mast cells in the periprosthetic breast capsule.

[BACKGROUND] Symptomatic capsular contracture occurs in about 10 % of primary breast augmentations and in more than double that rate in reconstruction after mastectomy, especially in the setting of radiation. Mast cells, traditionally associated with immune response and inflammation, secrete profibrotic mediators and may play a role in capsule formation and contracture. We analyzed the mast cell and fibroblast populations in breast capsule tissue from patients who underwent capsular excision.

[METHODS] Capsule tissue was collected from patients who underwent exchange of tissue expanders for permanent implants, revision of reconstruction, or revision augmentation. Breast capsule tissues were prepared for histological analyses of mast cells, fibroblasts, and collagen. Mast cells and fibroblasts were isolated from capsule tissue and screened for mediators and receptor expression.

[RESULTS] In breast capsule tissue, the average numbers of mast cells and fibroblasts were 9 ± 1/mm(2) and 33 ± 10/mm(2), respectively. There were significantly more mast cells on the posterior side than on the anterior side of the capsule tissue (12 ± 2 vs. 6 ± 1/mm(2), p < 0.01). Baker grade IV capsules had an increased number of fibroblasts compared to Baker grade I capsules (93 ± 9 vs. 40 ± 19/mm(2), p < 0.001). In breast capsule tissue, mast cells contained renin, histamine, and TGF-β, and their respective receptors, AT1R, H1R, and TGF-βRI were expressed by fibroblasts.

[CONCLUSION] These data indicate that within breast capsule tissue mast cells contain mediators that may activate neighboring fibroblasts. Understanding the role of mast cells in pathologic periprosthetic breast capsule formation may lead to novel therapies to prevent and treat capsular contracture.

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