Fabrication of all-trans retinoic acid loaded chitosan/tripolyphosphate lipid hybrid nanoparticles as a novel oral delivery approach for management of diabetic nephropathy in rats.

The present study aims to formulate all-trans retinoic acid (ATRA) loaded chitosan/tripolyphosphate lipid hybrid nanoparticles (CTLHNs) for enhancing its solubility and oral delivery. This is to improve ATRA therapeutic effect on diabetic nephropathy (DN). CTLHNs were prepared by o/w homogenization, employing stearic acid, to form lipid nanoparticles coated with chitosan that is stabilized against acidic pH via sodium tripolyphosphate crosslinking. Chitosan coated (F7) and naked lipid nanoparticles (F6) were also prepared for comparison with CTLHNs. In vitro characterization for the prepared formulations was performed comprising entrapment efficiency, particle size, zeta potential, transmission electron microscopy, FT-IR spectroscopy and x- ray diffraction. Stability of chitosan coat in GI fluid revealed that CTLHNs were more stable than F7. In vitro release indicated an enhanced release of ATRA. In vitro mucoadhesion study proved a notable mucoadhesive property for CTLHNs. In DN rat model, serum levels of creatinine and urea were elevated, over expression of tumor necrosis factor alpha (TNF-α), granulocyte macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1) were observed. In addition, adenosine monophosphate activated protein kinase (AMPK) and liver kinase B1 (LKB1) expressions were decreased in DN rats. Treatment with free ATRA and the selected formulations led to a significant amelioration of DN by reducing of creatinine, urea, TNF-α, ICAM-1, GM-CSF, VEGF levels as well as elevating AMPK and LKB1 levels. The order of activity was: CTLHNs > F7 > F6 > free ATRA, as proved by histopathological examination.