Carneiro Flavia, Kruithof Boudewijn Pt, Balani Kanthesh, Agarwal Arvind, Gaussin Vinciane, Kos Lidia
Department of Biological Sciences, Florida International University, Miami, FL, USA.
Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ, USA.
J Long Term Eff Med Implants. 2015;25(1-2):17-26. doi: 10.1615/jlongtermeffmedimplants.2015011748.
Heart valves are complex structures composed of organized layers of extracellular matrix, and interstitial and overlying endothelial cells. In this article, we present the specific localization of a population of melanocytes within the murine heart valves at ages important for their post-natal development. In all stages analyzed in our study, melanocytes were found in high numbers populating the atrial aspect of the tricuspid and mitral leaflets. The pulmonary valve did not present melanocytes. To characterize a putative role for the valve melanocytes, the dynamic nanomechanical properties of tricuspid leaftets containing large numbers or no melanocytes were measured. The stiffness coefficient of hyperpigmented leaflets was higher (11.5 GPa) than the ones from wild-type (7.5 GPa) and hypopigmented (5.5 GPa) leaflets. These results suggest that melanocytes may contribute to the mechanical properties of the heart valves. The arrangement of extracellular matrix molecules such as Collagen I and Versican B is responsible for the mechanical characteristics of the leaflets. Melanocytes were found to reside primarily in areas of Versican B expression. The patterns of expression of Collagen I and Versican B were not, however, disrupted in hyper or hypopigmented leaflets. Melanocytes may affect other extracellular matrix molecules to alter the valves' microenvironment.
心脏瓣膜是由细胞外基质、间质细胞和覆盖其上的内皮细胞组成的复杂结构。在本文中，我们展示了在小鼠心脏瓣膜出生后发育的重要时期，一群黑素细胞的具体定位。在我们研究分析的所有阶段，在三尖瓣和二尖瓣心房侧发现大量黑素细胞。肺动脉瓣中未发现黑素细胞。为了表征瓣膜黑素细胞的假定作用，我们测量了含有大量黑素细胞或不含黑素细胞的三尖瓣小叶的动态纳米力学特性。色素沉着过多的小叶的刚度系数（11.5吉帕）高于野生型（7.5吉帕）和色素沉着不足的小叶（5.5吉帕）。这些结果表明，黑素细胞可能有助于心脏瓣膜的力学性能。细胞外基质分子如I型胶原蛋白和多功能蛋白聚糖B的排列决定了小叶的力学特性。黑素细胞主要存在于多功能蛋白聚糖B表达的区域。然而，I型胶原蛋白和多功能蛋白聚糖B的表达模式在色素沉着过多或过少的小叶中并未受到破坏。黑素细胞可能会影响其他细胞外基质分子，从而改变瓣膜的微环境。
