Department of Experimental Medicine, University of Milano Bicocca, Monza, Italy.
J Physiol Pharmacol. 2011 Feb;62(1):45-53.
The aim of present work was to elucidate the interaction of solid lipid nanoparticles (SLNs) with cellular plasma-membrane to gain insight of intracellular drug delivery. To this aim we followed the uptake of coumarin-6 (a drug model) either free in the extracellular medium or loaded on SLN (c-SLN). Alveolar epithelial cells were exposed to a biocompatible concentration of c-SLN (0.01 mg/ml of tripalmitin) prepared by warm microemulsion whose lipid matrix was constituted by low melting point molecules (fatty acids, triglycerides). Intracellular fluorescence and preferential accumulation in the perinuclear region were increased by 54.8% on comparing c-SLN to the same amount of free coumarin-6 in the medium. Lowering temperature from 37 ° to 4 °C decreased the intracellular signal intensity by about 48% equally for the free as well as for loaded drug, thus suggesting the inhibition of a similar non-endocytotic entrance pathway. No specific co-localization of the fluorescence with intracellular organelles was found. The c-SLN calorimetric profile obtained with differential scanning calorimetry (DSC), revealing transition within the range 58-62 °C, altered remarkably upon incubation with cells, suggesting a change in SLN structure after association with cells membranes. We propose that the uptake of the model drug loaded on SLN is only partly related to the endocytotic pathway; it occurs despite the loss of integrity of the original SLN structure and it appears to be more efficient when the drug is vehicled rather than being free in the culture medium.
本工作旨在阐明固体脂质纳米粒（SLN）与细胞膜的相互作用，以深入了解细胞内药物递送。为此，我们研究了香豆素-6（一种药物模型）在游离于细胞外液中或负载于 SLN（c-SLN）时的摄取情况。肺泡上皮细胞暴露于生物相容性浓度的 c-SLN（0.01 mg/ml 的三棕榈酸甘油酯）中，该 SLN 由低熔点分子（脂肪酸、甘油三酯）组成的温微乳液制备。与细胞外液中相同浓度的游离香豆素-6相比，c-SLN 使细胞内荧光强度和优先在核周区积聚增加了 54.8%。将温度从 37°C 降至 4°C 使游离药物和负载药物的细胞内信号强度降低约 48%，这表明抑制了类似的非胞吞进入途径。未发现荧光与细胞内细胞器的特异性共定位。差示扫描量热法（DSC）获得的 c-SLN 量热曲线显示，在 58-62°C 范围内发生转变，与细胞孵育后明显改变，表明与细胞膜结合后 SLN 结构发生变化。我们提出，负载模型药物的 SLN 的摄取与内吞途径只有部分相关；尽管原始 SLN 结构的完整性丧失，但它仍会发生，而且当药物在载体中而不是在培养基中自由存在时，摄取效率似乎更高。
