Affecting one in 18,000 children, retinoblastoma is a form of intraocular cancer that affects the retina, the light-sensitive area located at the back of the eye. It attacks very early, since almost all of its victims are under 5 years old and, in two thirds of cases, it appears before the age of 2. Until now, the disease has been difficult to treat effectively due to the location of the tumor. But a scientific discovery could change everything.
For a drug treatment to reach the tumor, Live Science explains, it must pass through either the cornea (the protective layer at the front of the eye) or the side wall of the eyeball. Chemotherapy is usually given by injection, but this method can damage the eye.
Barriers to penetrate
Pharmacy researcher at the Chinese University of Shenyang and co-author of a study published by Science Advances, Yu Zhang explains that he was able to test on mice a new form of approach allowing young children to be spared painful and potentially invasive injections. This is based on the use of spermatozoa and their exosomes. These tiny vesicles, carried by seminal fluid, carry proteins that help the sperm pass through the protective layer of cells surrounding the egg in order to fertilize it.
Although the cells of the eye are very different from those of the egg, the mechanisms for crossing this biological barrier seemed sufficiently similar to Yu Zhang’s team to make them want to carry out some research. “This led us to investigate whether sperm-derived exosomes also possessed the ability to penetrate ocular barriers”summarizes the scientist to Live Science.
The method was tested with pig sperm, an animal already widely used in clinical research because it is considered safe. The scientific team administered eye drops containing porcine exosomes to mice, allowing them to demonstrate that these vesicles could deliver a potential treatment for retinoblastoma to the back of the eye.
The results are staggering: after thirty days of such treatment, the tumors only represented 2 to 3% of the size observed in untreated mice. “Given that the majority of affected patients are young children, therapies that preserve vision and minimize toxicity are of paramount importance for their lifelong well-being”concludes Yu Zhang, whose team now plans to conduct more in-depth research to ensure the effectiveness of this very unexpected treatment.
Ultimately, pig sperm will not necessarily be necessary for inoculation of the treatment, as explained by Owen Davies, specialist in extracellular vesicles at Loughborough University (UK), who says that other types of exosomes with the same properties, such as those derived from stem cells, could also be suitable.
