Nowadays, an active search for new drugs to treat ocular diseases occurs. The reason is that in the absence of therapy, these diseases lead to blindness. In our work uveitis and burn were observed as therapeutic goals.
Oxidative stress plays an important role in the pathogenesis of uveitis and burn, and injection of antioxidants may be effective. Antioxidant enzymes, such as superoxide dismutase (SOD) and catalase, are more effective in comparison with small molecular antioxidants, because enzymes react with substrate repeatedly. However, administering native enzymes to the eye in the form of drops is ineffective due to their rapid clearance. Therefore, it is important to create a drug delivery system that will possess long time of circulation and low immunogenicity.
To achieve this goal, SOD nanoparticles covered with chitosan were synthesized. Polymeric shell was used to decrease immunogenicity; chitosan was used to increase time of circulation.
Briefly, SOD nanoparticles were synthesized by mixing of SOD solution with protamine and PLE-PEG solutions sequentially, after that glutaraldehyde was added. Byproducts were removed by centrifugation through centrifugal filters. Nanoparticles of 50 nm in diameter with negative charge were obtained.
The release experiments were conducted using a dialysis container (100 kDa). SOD had being released from nanoparticles more slowly than the native SOD: 90% of SOD had released after 24 hours from the solution with the native enzyme, for the same time 30% of SOD had released from the solution with nanoparticles. This demonstrates that SOD is connected with the polymers strongly and the particles may have a large circulation time as opposed to the native enzyme.
Both nanoparticles and nanoparticles covered with chitosan were internalized by HEK293 cells whereas SOD was not. SOD nanopartices show therapeutic efficacy in preclinical trials on the model of uveitis and alkaline burn in rabbits.
Chitosan solution was added to nanoparticles to cover them. To confirm that particles were covered with chitosan, zeta-potential was measured: it changed from negative to positive values.
Thus, superoxide dismutase nanoparticles covered with chitosan were obtained. They seems to be perspective therapeutic agent due to improved stability and ability to internalize into cells.
