Stroke is the second leading cause of death worldwide and the most common cause of disability in adults. Ischemic stroke represents 80% of the cases. They cause oxygen and glucose deficit in the brain, leading to necrosis, edema formation, inflammation and apoptosis. Endogenous repair mechanisms, like cerebral plasticity, limit ischemia-linked damages.
Current treatments are only thrombolysis, which has to be realized within the first few hours after the event, and rehabilitation to reduce post-stroke disability. The use of stem cells is a promising therapy to reduce post-stroke disability. Several stem cells are used, including bone marrow-derived mesenchymal stem cells and neural stem cells. In France, stem cells are considered as Advanced Therapy Medicinal Products that include specific regulation for production, development and marketing.
In vivo studies demonstrated two mechanisms of action: direct replacement of damaged cells and trophic factors synthesis by stem cells that improve cerebral plasticity.
First clinical trials demonstrated an enhancement of post-stroke recovery thanks to biotherapy. No adverse effect is due to transplanted stem cells. However, the optimal time window, the best delivery routes and doses are still debated. Moreover, large-scale clinical tests have to be realized to validate these first results.
The main limitation of stem cell therapy in stroke is cell survival. Indeed, the persistence of transplanted cells remains very low, which greatly limits their effects, particularly for the replacement of damaged cells. Transplant survival seems to be improved by combining different therapeutic approaches. Biomaterials, including hydrogels (hyaluronic acid, collagen gel or Matrigel®), are currently being studied to improve the survival of transplanted cells by protecting the graft and promoting cell proliferation, migration and differentiation. The composition of these gels must be optimized.
BIOMIMESYS ® hydrogel by HCS Pharma could provide an interesting solution: indeed, it is physiological because it is based on hyaluronic acid, which is one of main component of the natural extracellular matrix. Moreover, in vitro studies in BIOMIMESYS® hydroscaffold by HCS Pharma demonstrated an improvement of neuronal cell survival. Thus, BIOMIMESYS® could be a promising solution to improve stem cell survival in regenerative medicine!