Schaller M, Korting H C, Schmid M H
Department of Dermatology, Ludwig Maximilians University, Munich, Germany.
Br J Dermatol. 1996 Mar;134(3):445-50.
There is evidence to suggest that human keratinocytes grown in vitro are capable of engulfing and subsequently disintegrating intact liposomes. However, as the liposomes used in this context did not carry an electron-dense marker, the possibility that the lamellar structures seen within the keratinocytes were composed of material produced within the cell could not be excluded. We therefore decided to investigate liposome-keratinocyte interaction using an electron-dense marker. Human keratinocytes obtained from juvenile foreskins were cultured in a serum-free medium, and subconfluent cultures were exposed to liposomally encapsulated and free silver sulphadiazine 1% (SSD), and a corresponding vehicle, for 5 min to 24 h. After fixation ultra-thin sections were analysed electron microscopically at magnifications of up to x85,000. Many keratinocytes treated with liposomal and free SSD showed marked damage to the plasma membranes and the cell organelles. The phagocytosis of intact liposomes was demonstrated by the appearance of silver-labelled unilamellar vesicles within the cytoplasm of undamaged keratinocytes. The labelled liposomes were found enclosed in cellular unit membranes, i.e. in lysosomes. In addition, perinuclear disintegration and release of the entrapped marker were observed. Silver particles, as present in liposomally encapsulated SSD, were found to be adequate markers for electron microscopy. Our results confirm the phagocytosis of intact liposomes by keratinocytes in vitro. In addition, the cytotoxic effects of liposomal (intended for the treatment of burns) and free SSD on human keratinocytes were studied in detail. Many keratinocytes treated for 10 min or more were severely affected.
有证据表明，体外培养的人角质形成细胞能够吞噬并随后分解完整的脂质体。然而，由于在此背景下使用的脂质体未携带电子致密标记物，因此不能排除角质形成细胞内所见的层状结构由细胞内产生的物质组成的可能性。因此，我们决定使用电子致密标记物来研究脂质体与角质形成细胞的相互作用。从青少年包皮中获取的人角质形成细胞在无血清培养基中培养，将亚汇合培养物暴露于脂质体包裹的和游离的1%磺胺嘧啶银（SSD）以及相应的赋形剂中5分钟至24小时。固定后，在高达85,000倍的放大倍数下对超薄切片进行电子显微镜分析。许多用脂质体包裹的和游离的SSD处理的角质形成细胞显示出质膜和细胞器的明显损伤。完整脂质体的吞噬作用通过未受损角质形成细胞胞质内出现银标记的单层囊泡得以证明。发现标记的脂质体被包裹在细胞单位膜内，即溶酶体中。此外，观察到核周崩解和被困标记物的释放。发现脂质体包裹的SSD中存在的银颗粒是电子显微镜的合适标记物。我们的结果证实了角质形成细胞在体外对完整脂质体的吞噬作用。此外，还详细研究了脂质体（用于治疗烧伤）和游离SSD对人角质形成细胞的细胞毒性作用。许多处理10分钟或更长时间的角质形成细胞受到严重影响。
