Treating eye disease using cells from the teeth

Macular Degeneration in an Eye
Macular Degeneration in an Eye

Researchers at Tufts University say that dental pulp from teeth could help treat macular degeneration, an eye disease that involves cellular debris and blood vessels forming in the retina over months to years and can lead to blindness. Effects of macular degeneration are often permanent and untreatable, and this debilitating disease affects more than 15 million Americans.

During embryo development, particular stem cells differentiate into retinal cells, dental pulp cells, fat cells or bone cells. Hence all these cell types, including retinal and dental pulp cells, are related by virtue of having similar origins. The research team are suggesting it may be possible to ‘reprogram’ dental pulp cells to become retinal cells. The leading researcher and stem cell biologist, Behzad Gerami-Naini, assistant professor at the School of Dental Medicine, shared that transforming cells requires manipulating the epigenome, which is a set of instructions that instruct a stem cell which genes to ‘turn on’ or ‘turn off’.

The “epigenome,” effectively acts like a series of molecular bookmarks, flagging snippets of DNA that contain the recipe to make a nerve cell, retina, tooth pulp or other specialized tissue. By rearranging those bookmarks, he says, it’s possible to alter which “recipe” a cell uses to determine its final form.

Gerami-Naini and his research team were previously successful in rebooting human skin cells, sending them back into embryonic-like form, known as induced pluripotent stem cells (iPS) that could potentially become any type of  cell in the human body. In the present study, they used iPS cells and transformed them into healthy retinal cells that theoretically could be implanted into the damaged eyes of patients suffering from macular degeneration.

However, there are roadblocks they need to overcome. If they use the original iPSc process that the Japanese researchers used, it requires injecting lab-made viruses into cells to alter their genes. This may be a stumbling block for approval by the Food and Drug Administration (FDA), as viruses may cause unintentional changes to a cell’s genetic code. Benjamin Chan, a clinical instructor of orthodontics at Tufts and research collaborator indicated that, “There are still many safety concerns. In order to perform clinical trials, you have to first show there won’t be any (unintended) viral effects (to the genome).” 

Illustration: Stuart Bradford
Illustration: Stuart Bradford

The use of dental pulp stem cells may help avoid those complications, as viruses are not used at all. Instead, the Tufts team believes it may be possible to manipulate the pulp cells’ DNA—effectively forcing them to change their form—by using existing chemicals and growth media.

Sheldom Rowan, a scientist in the Nutrition and Vision Laboratory at the Jean Mayer USDA Human Nutrition Research Centre on Ageing at Tufts, expressed that, “treating macular degeneration isn’t as simple as just injecting new retinal cells into the eye. The retina is a complex structure. Each cell has a specific orientation that needs to be maintained to keep the tissue healthy in the long run.”

As a result, the research team is working with David Kaplan, director of Tufts’ Tissue Engineering Resource Centre, to create a scaffold resembling the retinal membrane, using small silk structures to build a web-like formation. They intend to grow retinal cells on these microscopic scaffolds to ultimately create healthy three-dimensional retinal tissue that could be implanted in patients.

Gerami-Naini indicated that even though the research is still in the early stages, results seem promising, which is encouraging news for patients.

Source: Tufts University