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Gene therapy and stem cells take on sight-threatening eye diseases

Anders Kvanta’s research group is searching hard for potential new biomedical treatments for sight-threatening retinal diseases. One example is gene therapy for a particular form of inherited blindness. Another is stem cell-based treatment for the final stage of the dry form of age-related macular degeneration (AMD).

En man i svart t-shirt står framför ett buskage.
Anders Kvanta. Photo: Johanna Hanno
Consultant and professor Anders Kvanta believes that this research is at the heart of a biomedical revolution. Back in the mid-1990s, basic research conducted by his group contributed to the development of a novel biopharmaceutical drug for the wet form of AMD. Finally, the pathological blood vessels that form during the disease and which cause retinal haemorrhage could be treated.

“Nowadays there is a lot of focus on gene therapy and stem cell-based treatments, in that order. It is incredibly interesting. I see it as a journey of discovery,” says Anders Kvanta, who is both an eye surgeon at St. Erik Eye Hospital and a professor at Karolinska Institutet.

Gene therapy now being tested

When it comes to gene therapy, Anders Kvanta’s group, in collaboration with a pharmaceutical company, has turned its attention to patients with an unusual form of inherited blindness that is predominantly found in the Swedish region of Västerbotten. It affects around 70 people in Sweden. Like all forms of inherited blindness, retinitis pigmentosa is caused by a mutation in a gene that is essential for photoreceptor cell function.

A patient study is currently ongoing. In short, a corrective gene is planted in a virus, which is then transplanted into the eye by injection – a surgical procedure involving the vitreous body. The breakthrough for this type of treatment came last year, thanks to the efforts of another research group. However, each mutation requires its own unique treatment.

“Advances in the development of gene therapy are definitely raising hopes of successful treatments. Our study has only just started and it is, of course, incredibly exciting,” says Anders Kvanta.

Stem cell-based treatment one goal

The research group has also focused for some considerable time on a stem cell-based treatment for dry AMD, which affects the macula at the centre of the retina. The disease leads to a deterioration in a person’s central vision, as the pigment epithelial cells and photoreceptor cells in the macula die. It is this final stage, called geographic atrophy, that the researchers are studying.

The embryonic stem cells used as part of the research are pluripotent. This means that they can be turned into any other cells, in this case pigment epithelial cells and photoreceptor cells. The pigment epithelial cells have been transplanted into rabbits for the last five years, and this work has resulted in a number of scientific articles.

“It has gone brilliantly. At the same time, we have been able to identify a number of problems that we now need to address,” says Anders Kvanta.

One of the most important nuts to crack is the risk of rejection and the side effects of anti-rejection treatment caused by immunosuppression.

“Our dream now is to be able to manufacture cells that the immune system does not recognise. We hope to do this using a gene-editing technology called Crispr-Cas9. We also want the cells to provide protection against cancerous tumours, for instance. For this, we need to incorporate another level, with a gene for programmed cell death that can be switched on if needed.”

From basic research to patients

Anders Kvanta wants to emphasise that there is a great deal of basic research still to be done, but that the objective is to make this technology available to patients.

The time horizon for testing this technology on humans is, however, some way off. This is due in part to the research project having been expanded to include the gene-editing tool Crispr-Cas9, and also to the fact that describing and documenting all research stages for cell manufacture in accordance with the applicable rules is a time-consuming process. According to Anders Kvanta, there is, however, no doubt that development of biomedical technologies will continue.

“Biological targeted therapies continue to be refined. Gene therapy is developing at a rapid pace, and we have only just opened the door to stem cell-based treatment. Any improvement we can bring about for patients with a sight-threatening disease is incredibly valuable.”

Text: Lisa Thorsén

Facts

  • Approximately 80,000 people in Sweden and 5 million people in the West have geographic atrophy in at least one eye.
  • It is estimated that around 4,000 people in Sweden and 250,000 people in the West are affected by inherited blindness.
  • Anders Kvanta leads the research projects in question, together with researcher Fredrik Lanner at the Department of Clinical Science, Intervention and Technology at Karolinska Institutet, and Helder André, Head of Molecular and Cellular Research at St. Erik Eye Hospital.