EJMS

Abstract

Objective: Nanotechnology is a new discipline of science and engineering that has led to innovative approaches in many areas of medicine. Its applications in the screening, diagnosis, and treatment of disease are collectively referred to as nanomedicine. Silica nanoparticles are currently considered to be promising carriers for targeted drug delivery (TDD). However, the available data on their in vivo toxicity are limited. Aim: assessment of the possible histological alterations in the pulmonary alveoli after different duration (5 days, 60 days) of intravenous injection of silica nanoparticles in an attempt to cover and understand the in vivo cytotoxicity. Material & methods: the animals were divided into 2 groups: Group I (control group):10 adult male rats were injected intravenously with 0.9% sodium chloride. Group II (experimental group): 20 adult male rats injected intravenously with 7mg/kg body weight of silica nanoparticles (10-20 nanometer in diameter) they were further subdivided into: Subgroup IIa: duration five days. Subgroup IIb: duration sixty days. At the end of each duration, the specimens were taken from the lung and prepared for light and electron microscopic examination. Results: exposure to silica nanoparticles for 5 days induced severe degree of alterations in the pulmonary alveoli which includes marked collapse of the alveoli , proliferation of type II pneumocytes filled with abnormal lamellated structure, abnormal type I pneumocytes with abnormal nuclei, numerous macrophages, very thick interalveolar septa due to mononuclear cellular infiltration, congested blood vessels and increased collagen fibers. After sixty days the alveoli contain cellular debris and emphysematous changes occur as evident by destruction of the alveolar wall. Conclusion: Silica nanoparticles induced evident duration dependent damages in rat pulmonary alveoli.