“Because degradation of photoreceptors is believed to be a major factor in retinal diseases, such as retinitis pigmentosa and Leber’s congenital amaurosis, this finding, that horizontal cells are necessary for the normal survival of photoreceptor cells, is novel and significant,” says Mu. “Many retinal diseases are manifested by the degeneration of photoreceptor cells.”
This finding was unexpected, Mu explains, because most investigations into the degeneration of photoreceptor cells have involved genes that directly affect photoreceptor cell development.
“People haven’t been looking at horizontal cells,” he says. “We didn’t think that they’d be involved in photoreceptor cell degradation.
“With this finding, we have discovered that retinal horizontal cells are required for maintaining the integrity of the retina and that their deficiency can lead to retinal degradation,” explains Mu.
He notes that in most cases where photoreceptor cells die, it’s because they are somehow defective.
“But in this case, the photoreceptor cells are fine in the beginning, so the death of the photoreceptor cells is a secondary affair that is somehow driven by the deficiency in horizontal cells,” he says.