Blood protein ferries drug
doi:10.1038/nindia.2012.34 Published online 9 March 2012
Researchers have developed new nanosized drug-carriers from fibrin, a natural biopolymer produced during blood coagulation. The fibrin-derived nanotubes and nanoparticles can successfully deliver tacrolimus, an immunosuppressive drug, to target cells. Being comprised of a natural biopolymer makes these nanocarriers safe for use in biological systems.
Looking for a biocompatible material for aiding cell attachment, proliferation and tissue regeneration, researchers isolated fibrinogen from human blood plasma. They converted fibrinogen into fibrin using thrombin in a surfactant-free water-in-coconut-oil emulsion diffusion system, yielding fibrin nanoconstructs (FNCs) consisting of nanotubes and nanoparticles. They prepared tacrolimus-conjugated FNCs (T-FNCs) and VEGF (vascular endothelial growth factor)-conjugated FNCs (V-FNCs) and then carried out drug and growth factor release studies in animals and culture media.
The researchers found that nearly 97% of the tacrolimus was released from T- FNCs over a period of seven days. In rats, the serum concentration peaked after 24 hour, sustaining drug release for longer time periods and thus enhancing its therapeutic efficacy.
T-FNCs are good candidates for controlled drug release in blood and intracellular acidic environments, facilitating the intestinal transport of fat-loving molecules such as tacrolimus. V FNCs were found to release 84% of loaded vascular endothelial growth factor into culture media within a week. FNCs were easily degraded by enzymes and non-toxic to human mesenchymal stem cells, making them highly biocompatible.
"Being a natural protein, fibrin-derived nanoparticles can be synthesized from a patient's own blood cells," says lead researcher Krishna Prasad Chennazhi. "These nanoparticles can improve the blood vessels' growing potential in three-dimensional tissue engineering implants," he adds.