Smart Nanoparticles Based on Hyaluronic Acid for Redox-Responsive and CD44 Receptor-Mediated Targeting of Tumor

Since aggressive cancer cells highly express the CD44 receptor compared to normal cells, hyaluronic acid (HA) can be used for CD44 targeting molecule. Since glutathione (GSH) level is normally elevated in the intracellular compartment and in the tumor cell, the fact that disulfide bond can be cleaved by GSH is widely used for intracellular drug delivery.

HA was connected with poly(DL-lactide-co-glycolide) (PLGA) using disulfide linkage, and then a diblock copolymer (HAssLG) was prepared. Doxorubicin (DOX)-loaded HAssLG nanoparticles were prepared by dialysis procedures.

DOX-loaded HAssLG nanoparticles have spherical shapes with small particle size of less than 300 nm. In fluorescence measurement, DOX was dose-dependently liberated from nanoparticles by the addition of GSH. DOX release rate from HAssLG nanoparticles was increased by the addition of GSH. To confirm CD44 receptor-mediated endocytosis of nanoparticles, CD44-positive MDA-MB231 cells were employed and fluorescence intensity was strong when nanoparticles were treated to tumor cells. However, fluorescence intensity was significantly decreased through blocking of the CD44 receptor by pretreatment of cells with free HA. Fluorescence intensity of cells was increased again when GSH was added, indicating that HAssLG nanoparticles have CD44 receptor targetability and potential of redox-responsive drug delivery. For animal imaging study, CD44-positive MDA-MB231 cells and CD44-negative NIH3T3 cells were simultaneously implanted into the right flank and left flank of mice, respectively. Fluorescence intensity was significantly stronger at tumor mass of MDA-MB231 cells than solid mass of NIH3T3 cells, indicating that HAssLG nanoparticles were specifically delivered to tumor cells.

The results indicated that HAssLG nanoparticles have specificity against the CD44 receptor and can be used for anticancer drug targeting. We recommend HAssLG nanoparticles as a promising vehicle for cancer drug targeting.