Abstract
Purpose :
Following mechanical or chemical injury and during corneal infection, not only is heme-angiogenesis stimulated but also lymph angiogenesis. Maspin inhibits heme-angiogenesis in the corneal pocket model, as well as, inhibits tube formation and proliferation of heme microvascular endothelial cells. The purpose of this study was to determine whether maspin regulates two steps of the lymph angiogenesis process, endothelial cell tube formation and proliferation.
Methods :
Primary human lymph endothelial cells (HLECs) were incubated in the presence or absence of maspin, ovalbumin (control for maspin) or angiostatin (antiangiogenic) (10 pM to 100 nM) in a Matrigel based tube formation assay and in a BrdU Cell Proliferation ELISA. Tubes were analyzed using the Angiogenesis Analyzer for ImageJ.
Results :
Adding maspin to a HLEC tube assay results in decreased lymph endothelial cell tube formation in a biphasic manner. A maspin concentration of 100 nM increases tube formation compared to controls (120 ± 10.1% of control values, compared to 89 ± 4.5% of control when 0.1 µM angiostatin is tested). However, maspin at 1 nM results significantly inhibited tube formation relative to the control (58.8 ± 5.1%) and to ovalbumin (74.6 ± 4.3%). At 10 pM maspin HLEC tube formation returned to control levels (97.7 ± 8.4% of control). BrdU ELISA tests using maspin at concentrations from 100 nM to 1 pM showed that maspin and angiostatin had no effect on proliferation of HLECs. This suggests that the decrease in tube formation on Matrigel wells is not due to cell death.
Conclusions :
The effect of maspin on tube formation of HLEC cells is biphasic suggesting that maspin may differentially regulate lymph angiogenesis depending upon the amount of maspin is present in the injured cornea. The 1 nM maspin level is consistent with that in the extracellular matrix of the normal cornea. The 100 nM maspin level is consistent with the predicted level if maspin is released from corneal cells. This level would be only found major corneal damage under conditions requiring ingrowth of lymphatic vessels into the cornea.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.