Sergio Crespo-García’s research provides a little optimism in the possibility of treating diabetic retinopathy

18 June 2021

Imagine that you're on a trip and on your way to your destination you pass through a beautiful spot. You stop to take a photo, but when you look at the screen there are black spots blotting out the horizon. You assume that there must be a problem with your sensor, the camera’s eye. In this case, there would be a simple solution: repair your camera or get a new one. But what if you saw these stains with your own eyes.

This is the experience of the first symptoms of people with type-1 or type-2 diabetes who end up developing diabetic retinopathy, the most common cause of blindness in people aged 20 to 65 in industrialised countries.

Dark stains that hinder the central field of vision in people with diabetic retinopathy.

Dark stains that hinder the central field of vision in people with diabetic retinopathy.

“Smoking and diets rich in sugars and saturated fats can affect a range of organs, including the eyes”, said Sergio Crespo-García, a researcher at the Hôpital Maisonneuve-Rosemont Research Center, part of the University of Montreal. “High levels of sugar cause unbridled growth of the blood vessels in the retina, which are in charge of providing nutrients to the specific neurons for visions,” he said. As such, the retina activates a series of mechanisms to combat these blood vessels that “shouldn’t be there”, for example through synthesising and accumulating a huge number of inflammatory molecules to remove the sick cells, which leads to a loss of vision.

Sergio Crespo-García is a researcher at the Hôpital Maisonneuve-Rosemont Research Center, part of the University of Montreal.Sergio Crespo-García

Although a falling number of patients suffer from severe loss of vision, the fact of the matter is that once the first symptoms take hold, it's very difficult to revert them. “Until now, there was no sure-fire treatment to cure this pathology beyond laser surgery to burn off the active vascularisation point in the retina, injections to inhibit vascular growth or corticosteroid injections. According to Sergio, the problem with these medications is that they cannot differentiate between healthy and proliferative or sick blood vessels. “Sometimes, the cocktail is not very effective, and it can even be harmful for some patients if kept up over time.”

However, some weeks ago, this fellow’s recent discoveries provided some optimism in terms of a possible treatment. “The medication developed by UNITY Biotechnology —in stage 2 of clinical trials— which we are currently studying goes to the root of the problem. It selectively picks out the pathological blood vessels while leaving the healthy ones intact, which adds a level of safety and efficiency to the current treatment,” Sergio added. The promising results, published in the indexed journal Cell Metabolism, were what won him the Relève Étoile Jacques-Genest from the FRQ in Quebec some weeks ago. “It's an honour to receive an award. However, acknowledgment aside, being published in such a prestigious journal is a green light to keep working in the same direction. An article that only spans a few pages is the result of huge investment and the full-time effort of a team over various years. It's gratifying to see that other people think that what you do has a positive impact and that it will lead to a change in the current standards,” he said. 

Sergio’s career took off in 2012, after doing an MSc in Genetics and Cellular Biology at the Complutense University of Madrid with the support of a fellowship from the ”la Caixa” Foundation. “It gave me the chance to take my first steps in the laboratory as a researcher. It was like an incubator that later allowed me to apply for other grants such as the Marie Curie ITN, which helped me to finish my PhD in Experimental Ophthalmology and Biomedicine at Charité – Universitätsmedizin in Berlin,” he said. However, it was not until 2016 when he travelled to Japan to present his work at an ophthalmology conference that he met the neuroscientist Przemyslaw (Mike) Sapieha, his current team leader. “Professor Sapieha’s laboratory had become very prestigious over the last decade, so I was aware of his lines of investigation and the huge advances being made in the field. When we met in Tokyo, we connected immediately, and after half an hour of conversation, he formally invited me to move to Canada.” A decision that “he doesn’t regret,” he pointed out. 

The research he conducted alongside his colleagues in Montreal also identified, for the first time ever, the predisposition of the “sick” blood vessels towards cellular senescence, a characteristic they share with diseases such as cancer or those that are particularly linked with ageing. “As the study moves forwards, we will broaden our lines of research into diseases with similar molecular features. This could be the catalyst for a lot more research and medical trials,” he concluded.

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