Conclusion
A combination of inflammatory and mechanical factors may disrupt amniotic membrane biomechanics and matrix composition.
Discussion
Fibre orientation has a significant effect on amniotic strength. Tensile strain increased Cx43/COX-2 expression and PGE2 release resulting in tissue softening mediated by enhanced GAG levels and a reduction in collagen/elastin content. Conclusion: A combination of inflammatory and mechanical factors may disrupt amniotic membrane biomechanics and matrix composition.
Methods
Human amniotic membranes isolated from the cervix (CAM) or placenta regions (PAM) were examined by second harmonic generation to identify collagen orientation and subjected to tensile testing to failure. In separate experiments, specimens were subjected to cyclic tensile strain (2%, 1 Hz) for 24 h. Specimens were examined for Cx43 by immunofluorescence confocal microscopy and expression of COX-2 and Cx43 by RT-qPCR. PGE2, collagen, elastin and glycosaminoglycan (GAG) levels were analysed by biochemical assay.
Results
Values for tensile strength were significantly higher in PAM than CAM with mechanical parameters dependent on collagen orientation. Gene expression for Cx43 and COX-2 was enhanced by tensile strain leading to increased PGE2 release and GAG levels in PAM and CAM when compared to unstrained controls. In contrast, collagen and elastin content was reduced by tensile strain in PAM and CAM.