Elastic fibers in the aortic valve spongiosa: a fresh perspective on its structure and role in overall tissue function

摘要

This study characterized the elastic fiber structure within the aortic valve spongiosa, the middle layer of the tri-laminate leaflet. The layer is rich in glycosaminoglycans and proteoglycans, through which it resists compression and lubricates shear between the outer layers. Elastin in this layer forms a fine, interweaving structure, yet it is unclear how this particular structure, which uses elasticity to preload the leaflet, assists spongiosa function. In this study, immunohistochemistry and scanning electron microscopy were used to characterize spongiosa elastin, as well as investigate regional differences in structure. Immunohistochemistry for elastin highlighted an intermediate structure that varied in thickness and density between regions. In particular, the spongiosa elastin was thicker in the hinge and coaptation region than in the belly. Scanning electron microscopy of NaOH-digested leaflets showed a rectilinear pattern of elastic fibers in the hinge and coaptation region, as opposed to a radially oriented stripe pattern in the belly. In conclusion, elastic fibers in the spongiosa connect the two outer layers and vary regionally in structure, while possible playing a role in responding to regionally specific loading patterns.