Tissue localization of nanoparticles is altered due to hypoxia resulting in poor efficacy of curcumin nanoparticles in pulmonary hypertension.

The present study is an attempt to leverage therapeutic benefits of curcumin in pulmonary hypertension by encapsulating it in biodegradable poly(lactide-co-glycolic) acid nanoparticles. Pulmonary hypertension is induced in experimental animals by subjecting them to chronic hypoxic conditions. The ability of curcumin encapsulated nanoparticles to manage pulmonary hypertension is measured by right ventricular hypertrophy, haematocrit, vascular remodelling and target tissue levels of curcumin. Further, single oral dose tissue distribution of the nanoparticulate curcumin was also assessed under normoxic and hypoxic conditions. Orally administered nanoparticulate curcumin failed to offer any protection against hypoxia induced pulmonary hypertension as indicated by insignificant changes in right ventricular hypertrophy and vascular remodelling that are similar to untreated groups. A significant difference in the target tissue levels was observed between normoxic vs. hypoxic rats. The study suggests that hypoxia has a major role in the particle localization in lungs probably due to the altered blood flow, increased barrier properties of the lung vasculature and decreased endocytosis. The target tissue levels of curcumin under hypoxia are much lower to that achieved in normoxic rats probably due to difference in particle dynamics, resulting in the failure of treatment.