A multielectrode array‐based hypoxia model for the analysis of electrical activity in murine retinae

Abstract

Several eye diseases, for example, retinal artery occlusion, diabetic retinopathy, and glaucoma, are associated with retinal hypoxia. The lack of oxygen in the retina, especially in retinal ganglion cells (RGCs), causes cell damage up to cell degeneration and leads to blindness. Using multielectrode array recordings, an ex vivo hypoxia acute model was established to analyze the electrical activity of murine wild‐type retinae under hypoxic stress conditions. Hypoxia was induced by exchanging the perfusion with oxygen‐saturated medium by nitrogen‐saturated medium. Hypoxic periods of 0 min (control) up to 60 min were tested on the retinae of adult female C57BL/6J mice. The electrical RGC activity vanished during hypoxia, but conditionally returned after the reestablishment of conventional test conditions. With increasing duration of hypoxia, the returning RGC activity decreased. After a hypoxic period of 30 min and a subsequent recovery time of 30 min, 59.43 ± 11.35% of the initially active channels showed a restored RGC activity. The survival rate of retinal cells after hypoxic stress was analyzed by a live/dead staining assay using two‐photon laser scanning microscopy. For detailed information about molecular changes caused by hypoxia, a microarray gene expression analysis was performed. Furthermore, the effect of 2‐aminoethanesulfonic acid (taurine, 1 mM) on retinae under hypoxic stress was tested. Treatment with taurine resulted in an increase in the RGC response rate after hypoxia and also increased the survival rate of retinal cells under hypoxic stress, confirming its potential as promising candidate for neuroprotective therapies of eye diseases.

Effects of Hydrostatic Pressure on Electrical Retinal Activity in a Multielectrode Array-Based ex vivo Glaucoma Acute Model

“…The effect of hypoxic stress on the functionality and survival of RGCs has been demonstrated in our previous work (Ingensiep et al, 2021) as well as in multiple other studies (Gross et al, 1999;Kergoat et al, 2006;Janaky et al, 2007;Tan et al, 2011). RGCs transit into a stress mode, even after short-time hypoxia, where no spontaneous electrical activity and no response to electrical or light stimuli can be recorded.…”

“…Although high IOP is considered the main risk factor in glaucoma, we showed that the sheer mechanical stress of pressure does not seem to affect the retinal functionality in the acute model. In contrast, we showed that hypoxic stress has a dramatic effect on the RGCs' electrical activity and their survival rate (Ingensiep et al, 2021). Hypoxia can be induced in vivo by impaired blood flow under high IOP (Andreeva et al, 2014;Wiemann et al, 2021).…”

“…Retina preparation was performed as previously described (Ingensiep et al, 2021). Briefly, both eyes of an animal were enucleated directly after sacrifice and put into freshly carbogenated Ames' medium.…”

“…The live/dead double stained retinae were analyzed via twophoton laser scanning microscopy (TPLSM) as described earlier (Ingensiep et al, 2021). Imaging was done with a two-photon microscope (Olympus Fluoview FV1000 MPE, Olympus Corporation, Tokyo, Japan) attached to a pulsed Ti:Sapphire laser (MaiTai DeepSee, SpectraPhysics, Santa Clara, CA, United States).…”

In the Eye of the Storm: Bi-Directional Electrophysiological Investigation of the Intact Retina

“…Primarily, explanted retinas lack the metabolic environment of the eye, and some of its electrophysiological properties under ex vivo conditions may be distorted. For example, identifying stimulation parameters for retinal implant performance optimization may depend on retina metabolic conditions (Ingensiep et al, 2021) and retina explant viability (Balasubramanian and Shabanian, 2020). Therefore, ex vivo stimulation studies, for example, may provide only a partial picture of retinal response to electrical stimulation.…”