Retinitis pigmentosa is a genetic disorder that leads to severe vision impairment and blindness. The photoreceptors die off in a self-propelling cycle of rod and cone dysfunction, leading to glial activation and death, leading to more dysfunction. There are a few experimental treatments but no widespread effective treatment or cure. Cassia seed is used in traditional Chinese medicine and is often prescribed for eye problems. Studies suggest it can be a beneficial treatment for glaucoma and cataracts but it has not been studied as a preventative medication. From Taipei Medical University, Lin et al, in their article, “The natural retinoprotectant chrysophanol attenuated photoreceptor cell apoptosis in an N-methyl-N-nitrosourea-induced mouse model of retinal degeneration,” used the Phoenix MICRON® OCT to demonstrate cassia seed’s apoptosis-prevention effect that lead to less retinal layer disruption and preserved vision.
Lin et al induced photoreceptor apoptosis as a mouse model of retinitis pigmentosa using N-methyl-N-nitrosourea (MNU). The Phoenix MICRON® OCT produced images that clearly show dose-dependent outer nuclear layer degeneration seven days after MNU-administration (Figure 1A). Electroretinogram analysis revealed decreased a- and b-wave amplitude and time. Chrysophanol is the active ingredient in cassia seed and has been shown to have anti-oxidative, anti-hyperlipidemia, and anti-inflammatory effects. The mice received three days of chrysophanol treatment starting the day before MNU-administration. The treatment rescued the a- and b-wave responses.
Lin et al used the layer-analysis software Insight, exclusive to the Phoenix MICRON® OCT, to confirm in micrometers the degeneration shown by the OCT images: the MNU-treatment significantly reduced the cumulative thickness of the outer nuclear layer, inner segments, and outer segments (Figure 2A and B). Chrysophanol prevented this loss (Figure 2A and B), and this effect was confirmed with histology from ex-vivo eyes. Molecular analysis revealed that chrysophanol appears to prevent the inappropriate apopotosis of photoreceptors, rescuing function of the eye. This discovery is exciting as inappropriate apoptosis is involved in several different ocular diseases, meaning cassia seed and its active ingredient chrysophanol may be a new therapeutic avenue.
In summary, Lin et al conducted a thorough study from longitudinal live eye imaging with the Phoenix MICRON® OCT to detailed molecular analysis to discover that cassia seed and the active ingredient chrysophanol inhibited retinal degeneration in a mouse model of retinitis pigmentosa.
Citation: Lin, F-L, Lin, C-H, Ho, J-D, Yen, J-L, Chang, H-M, Chiou, G.C.Y., Cheng, Y-W, and Hsiaoa, G. (2017). The natural retinoprotectant chrysophanol attenuated photoreceptor cell apoptosis in an N-methyl-N-nitrosourea-induced mouse model of retinal degeneration. Sci Rep.; 7: 41086.