A promising therapy to combat osteoarthritis

Osteoarthritis, which can appear from the age of 40, becomes more widespread with age, affecting 65% of the population over 65 and 80% of the population over 80. This degenerative condition of the cartilage causes friction causing inflammation, pain, swelling and stiffness, sometimes creating real disabilities. It mainly affects the joints of the knees, hips, spine and hands.

Despite the extent of the affected population, relatively little research is dedicated to this multifactorial disease. Until now, affected people are offered anti-inflammatory treatments to reduce pain or lubricants, such as hyaluronic acid (naturally present in the body, but whose production decreases with age) to limit the friction. In the most problematic cases, the installation of prostheses is necessary.

The groups of Éric Allémann, full professor in the pharmaceutical sciences section of the Faculty of Sciences of the University of Geneva (UNIGE), and Olivier Jordan, teaching and research professor, have been interested for around fifteen years developing new therapeutic treatments. They contribute to several areas of research, including that of injecting stem cells into the joints which will naturally release biomolecules, such as growth factors, capable of interacting with cartilage cells to reduce inflammation and stimulate the growth of new cells.

“The problem is that these stem cells, which come from another part of the patient’s body (usually fat or bone marrow), do not find themselves in an optimal environment for their growth and die very quickly, without having had time to release enough molecules with beneficial effects on degenerating cells,” explains Paula Gonzalez-Fernandez, doctoral student in the laboratory of Éric Allémann and first author of the study published in the “International Journal of Pharmaceutics”.

“This is particularly true for injections of stem cells into joints, since these tissues are not vascularized and are therefore not supplied with nutrients and oxygen,” continues the researcher.

To get around this problem, scientists have tried to provide these stem cells with a Source of energy to increase their lifespan. “Glucose was a good candidate, but it is too quickly eliminated naturally by body fluids. The subtlety of our work was to attach the glucose molecules to hyaluronic acid, so that the glucose is not immediately eliminated, but is released in small, regular doses,” explains Olivier Jordan.

The authors of the study therefore tested the lifespan of stem cells with or without modified glucose, under laboratory conditions. They found that the stem cells, injected into cell cultures of cartilage tissue, survived more than three days in the presence of glucose associated with hyaluronic acid, compared to less than 24 hours in the absence of this glucose. These three days are sufficient to release the growth factors and activating molecules responsible for cartilage regeneration.

“These results are very encouraging and promising, but are still only at the cell culture stage in the laboratory. Our next step is to confirm these results in an animal model,” indicates Éric Allémann. This approach, which consists of adding a nutrient (glucose in this case) to hyaluronic acid, opens new perspectives for stem cell therapies in poorly vascularized and nutrient-poor environments, such as osteoarthritic joints, but also for other regenerative therapies.