Biocompatibility of poly(D,L-lactide-co-glycolide) nanoparticles conjugated with alendronate

Nanoparticles made of a conjugate of poly(D,L-lactide-co-glycolide) with alendronate (PLGAeALE NPs), were prepared by emulsion/solventevaporation technique. The conjugation yield, determined by MALDI TOF analysis, was 30e35%. PLGAeALE NPs size, evaluated byphoton correlation spectroscopy, was 198.7 0.2 nm. Haemocompatibility studies using different concentrations of PLGAeALE NPs didnot show any significant effect on haemolysis, leukocyte number, platelet activation, APTT and complement consumption, in comparisonwith blood incubated with phosphate buffered saline (PBS). A significant reduction of the prothrombin activity was demonstrated after incubationwith 560 mg/ml of PLGAeALE NPs; a significant increase was observed at the highest dilutions. The viability of human umbilical veinendothelial cells and bone marrow stromal cells (BMSC), evaluated through the neutral red test, was not affected by PLGAeALE NPs. Therewere no significant differences in cell-associated alkaline phosphatase between BMSC incubated with PLGAeALE NP- and PBS-added media.These results demonstrated that PLGAeALE NPs had an acceptable degree of blood compatibility and were not cytotoxic; therefore, they maybe considered suitable for intravenous administration.