SummaryCorneal scarring due to injury is a leading cause of blindness worldwide and results from dysregulated inflammation and angiogenesis during wound healing. Here we demonstrate that the extracellular matrix metalloproteinase MMP12 (macrophage metalloelastase) is an important regulator of these repair processes. Chemical injury resulted in higher expression of the fibrotic markers a-smooth muscle actin and type I collagen, and increased levels of angiogenesis in corneas of Mmp12 2/2 mice compared with corneas of wild-type mice. In vivo, we observed altered immune cell dynamics in Mmp12 2/2 corneas by confocal imaging. We determined that the altered dynamics were the result of an altered inflammatory response, with delayed neutrophil infiltration during the first day and excessive macrophage infiltration 6 days later, mediated by altered expression levels of chemokines CXCL1 and CCL2, respectively. Corneal repair returned to normal upon inhibition of these chemokines. Taken together, these data show that MMP12 has a protective effect on corneal fibrosis during wound repair through regulation of immune cell infiltration and angiogenesis.

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Background: In the past decade, surgeons have increasingly advocated for a return to prepectoral breast reconstruction with claims that surgical mesh (including acellular dermal matrix) can reduce complication rates. However, numerous surgical and implant advancements have occurred in the decades since the initial prepectoral studies, and it is unclear whether mesh is solely responsible for the touted benefits. Methods: The authors conducted a systematic review of all English language articles reporting original data for prepectoral implant-based breast reconstruction. Articles presenting duplicate data were excluded. Complications were recorded and calculated on a per-breast basis and separated as mesh-assisted, no-mesh prior to 2006, and no-mesh after 2006 (date of first silicone gel–filled breast implant approval). Capsular contracture comparisons were adjusted for duration of follow-up. Results: A total of 58 articles were included encompassing 3120 patients from 1966 to 2019. The majority of the included studies were retrospective case series. Reported complication outcomes were variable, with no significant difference between groups in hematoma, infection, or explantation rates. Capsular contracture rates were higher in historical no-mesh cohorts, whereas seroma rates were higher in contemporary no-mesh cohorts. Conclusions: Limited data exist to understand the benefits of surgical mesh devices in prepectoral breast reconstruction. Level I studies with an appropriate control group are needed to better understand the specific role of mesh for these procedures. Existing data are inconclusive but suggest that prepectoral breast reconstruction can be safely performed without surgical mesh.