Primary open angle glaucoma (POAG) is the second leading blind disease in the world. The pathological mechanism of glaucoma has been still debated. The general representative symptom of glaucoma is the abnormally increased intraocular pressure (IOP), which causes optic nerve damage and permanent vision loss. According to previous research, the breakdown of production and clearance of aqueous humor (AH) increases the IOP. The specific ocular tissue called as a “trabecular meshwork (TM)” in the AH outflow drainage system is believed to play an important role in the regulation of IOP in the normal range from 15mmHg to 22mmHg. Clinical treatments of glaucoma are to lower the IOP to the normal range. In general, the invasive surgical techniques such as “trabeculectomy”, and “laser trabeculoplasty” are performed with relevant medications. Although the coagulation of tissue by laser based surgeries is less invasive than surgical removal, patients are still exposed to the post-operative risks such as tissue coagulation, inflammation, cornea injury, and cataract. These may cause secondary visual loss.
In this work, due to the complex morphology of TM tissue and interrelated parameters involved in the IOP regulation, the key factors governing the outflow facility are investigated using multi-disciplinary approaches. First, the perfusion test was conducted to examine the effect of low fluence diode laser (wavelength: 830nm) which generates the non-invasive level of energy on the hydraulic resistivity of in vitro cultured TM monolayer on the solid porous membrane. The expression of heat shock protein upon low fluence laser treatment was also assessed. The dose-dependent effect of glucocorticoid drug (dexamethasone) was investigated using the electrical impedance spectroscopy. To take into account the three dimensional (3D) porous morphology of TM, polymer based micro/nanofibrous membranes mimicking the in vivo-like environment of natural TM was constructed by combining an array of electrospinning and microfabrication technologies. The effect of topographical parameters on 3D TM growth was quantified. Finally, a 3D co-culturing strategy was developed, which allows positioning of TM cells and Schlemm’s canal (SC) endothelial cells within a single specimen to mimic the natural composite cellular structures in the outflow facility of aqueous humor.
This work presents a set of enabling technology for systematic in vitro investigation of the outflow facility of AH. This is critical for exploring the key factor that governs the IOP and is expected to provide useful insights for therapeutics of POAG. The outcome can also be applicable for in vitro study of other tissues with morphological complexity.