Gel carrier for intraarticular BMP injection, with chondroprotective properties. Covalent cross-linking of hyaluronic acid in the presence of heparin makes it possible to obtain nanoparticles of a given size, having suitable rheological properties and resistant to enzymes. Polyethylene glycol diglycidyl ether (PEGDE) is used as the crosslinking reagent. This gel does not cause an inflammatory response and remains at the injection site.