Abstract
AimsWe developed a glaucoma‐on‐a‐chip model to evaluate the viability of retinal ganglion cells (RGCs) against high pressure and the potential effect of neuroprotection.MethodsA three‐layered chip consisting of interconnecting microchannels and culture wells was designed and fabricated from poly‐methyl methacrylate sheets. The bottom surface of the wells was modified by air plasma and coated with different membranes to provide a suitable extracellular microenvironment. RGCs were purified from postnatal Wistar rats by magnetic assisted cell sorting up to 70% and characterized by flow cytometry and immunocytochemistry. The cultured RGCs were exposed to normal (15 mmHg) or elevated pressure (33 mmHg) for 6, 12, 24, 36, and 48 hr, with and without adding brain‐derived neurotrophic factor (BDNF) or a novel BDNF mimetic (RNYK).ResultsMultiple inlet ports allow culture media and gas into the wells under elevated hydrostatic pressure. PDL/laminin formed the best supporting membrane. RGC survival rates were 85%, 78%, 70%, 67%, and 61% under normal pressure versus 40%, 22%, 18%, 12%, and 10% under high pressure at 6, 12, 24, 36, and 48 hr, respectively. BDNF and RNYK separately reduced RGC death rates about twofold under both normal and elevated pressures.ConclusionThis model recapitulated the effects of elevated pressure over relatively short time periods and demonstrated the neuroprotective effects of BDNF and RNYK.
Highlights
Glaucoma is a collective term used to define a group of neurodegenerative processes affecting the entire visual pathway best distinguished by progressive, irreversible destruction and death of retinal ganglion cells (RGCs)
intraocular pressure (IOP) is regulated by the balance between aqueous humor secretion into the anterior chamber on one hand and its drainage via the trabecular meshwork or the uveoscleral outflow pathways on the other hand [2]
We studied RGC survival under normal versus elevated hydrostatic pressures and compared survival of these cells when treated with a neuroprotective growth factor or a mimicry peptide, named RNYK, as a putative agonist of neurotrophic tyrosine kinase receptor type 2 (NTRK2) [33]
Summary
Glaucoma is a collective term used to define a group of neurodegenerative processes affecting the entire visual pathway best distinguished by progressive, irreversible destruction and death of retinal ganglion cells (RGCs). The primary risk factor for progression and development of glaucoma is elevated intraocular pressure (IOP). Several experimental in vivo glaucoma models have been developed and used for studies on glaucoma mechanisms. These include laser photocoagulation of the Perilimbal region [4], red blood cell or microbeads injection into the anterior chamber [5, 6], Episcleral vein obstruction [7], and Episcleral vein saline injection [8,9,10]. While in vivo animal models are indispensable to determine what events occur in live organisms, these strategies typically involve poorly defined and uncontrollable factors and the results can be difficult to understand at cellular and molecular levels [13]
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