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Efficacy of 670nm Light Therapy to Protect against Photoreceptor Cell Death Is Dependent on the Severity of Damage


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1 The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, ACT 2601, Australia
 

Photobiomodulation at a wavelength of 670nm has been shown to be effective in preventing photoreceptor cell death in the retina. We treated Sprague-Dawley (SD) rats with varying doses of 670nm light (9; 18; 36; 90 J/cm2) before exposing them to different intensities of damaging white light (750; 1000; 1500 lux). 670 nm light exhibited a biphasic response in its amelioration of cell death in light-induced degeneration in vivo. Lower light damage intensities required lower doses of 670 nm light to reduce TUNEL cell death. At higher damage intensities, the highest dose of 670 nm light showed protection. In vitro, the Seahorse XFe96 Extracellular Flux Analyzer revealed that 670 nmlight directly influences mitochondrialmetabolism by increasing the spare respiratory capacity of mitochondria in 661W photoreceptor-like cells in light damaged conditions. Our findings further support the use of 670 nm light as an effective treatment against retinal degeneration as well as shedding light on the mechanism of protection through the increase of the mitochondrial spare respiratory capacity.
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  • Efficacy of 670nm Light Therapy to Protect against Photoreceptor Cell Death Is Dependent on the Severity of Damage

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Authors

Joshua A. Chu-Tan
The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, ACT 2601, Australia
Matt Rutar
The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, ACT 2601, Australia
Kartik Saxena
The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, ACT 2601, Australia
Yunlu Wu
The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, ACT 2601, Australia
Lauren Howitt
The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, ACT 2601, Australia
Krisztina Valter
The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, ACT 2601, Australia
Jan Provis
The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, ACT 2601, Australia
Riccardo Natoli
The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, ACT 2601, Australia

Abstract


Photobiomodulation at a wavelength of 670nm has been shown to be effective in preventing photoreceptor cell death in the retina. We treated Sprague-Dawley (SD) rats with varying doses of 670nm light (9; 18; 36; 90 J/cm2) before exposing them to different intensities of damaging white light (750; 1000; 1500 lux). 670 nm light exhibited a biphasic response in its amelioration of cell death in light-induced degeneration in vivo. Lower light damage intensities required lower doses of 670 nm light to reduce TUNEL cell death. At higher damage intensities, the highest dose of 670 nm light showed protection. In vitro, the Seahorse XFe96 Extracellular Flux Analyzer revealed that 670 nmlight directly influences mitochondrialmetabolism by increasing the spare respiratory capacity of mitochondria in 661W photoreceptor-like cells in light damaged conditions. Our findings further support the use of 670 nm light as an effective treatment against retinal degeneration as well as shedding light on the mechanism of protection through the increase of the mitochondrial spare respiratory capacity.