Niesner Raluca, Peker Bülent, Schlüsche Peter, Gericke Karl-Heinz, Hoffmann Christine, Hahne Dagmar, Müller-Goymann Christel
Institute for Physical and Theoretical Chemistry, Technical University, Braunschweig, Germany.
Pharm Res. 2005 Jul;22(7):1079-87. doi: 10.1007/s11095-005-5304-6. Epub 2005 Jul 22.
The development of substitutes for the human skin, e.g., artificial skin constructs (ASCs), is of particular importance for pharmaceutical and dermatologic research because they represent economical test samples for the validation of new drugs. In this regard, it is essential for the skin substitutes to be reliable models of the genuine skin, i.e., to have similar morphology and functionality. Particularly important is the barrier function, i.e., the selective permeability of the skin, which is strongly related to the epidermal pH gradient. Because the pH significantly influences the permeation profile of ionizable drugs such as nonsteroidal anti-inflammatory drugs, it is of major importance to quantitatively measure the epidermal pH gradient of the ASC and compare it to that of genuine skin.
Using three-dimensional fluorescence lifetime imaging combined with two-photon scanning microscopy, we measured with submicron resolution the three-dimensional pH gradient in the epidermis of ASCs stained with 2',7'-bis-(2-carboxyethyl)-5/6-carboxyfluorescein.
Similar to genuine skin, the surface of the artificial epidermis has an acidic character (pH 5.9), whereas in the deeper layers the pH increases up to 7.0. Moreover, the pH gradient differs in the cell interior (maximally 7.2) and in the intercellular matrix (maximally 6.6). Apart from the similitude of the pH distribution, the genuine and the artificial skin prove to have similar morphologies and to be characterized by similar distributions of the refractive index.
Artificial skin is a reliable model of genuine human skin, e.g., in permeability studies, because it is characterized by a similar pH gradient, a similar morphology, and a similar distribution of the refractive index to that of genuine skin.
开发人体皮肤替代品，如人工皮肤构建体（ASC），对药物和皮肤病学研究尤为重要，因为它们是验证新药的经济测试样本。在这方面，皮肤替代品必须是真实皮肤的可靠模型，即具有相似的形态和功能。特别重要的是屏障功能，即皮肤的选择性通透性，它与表皮pH梯度密切相关。由于pH值显著影响非甾体抗炎药等可电离药物的渗透情况，因此定量测量ASC的表皮pH梯度并将其与真实皮肤的进行比较至关重要。
我们使用三维荧光寿命成像结合双光子扫描显微镜，以亚微米分辨率测量了用2',7'-双（2-羧乙基）-5/6-羧基荧光素染色的ASC表皮中的三维pH梯度。
与真实皮肤相似，人工表皮表面呈酸性（pH 5.9），而在较深层中pH值升高至7.0。此外，细胞内部（最高7.2）和细胞间基质（最高6.6）的pH梯度有所不同。除了pH分布相似外，真实皮肤和人工皮肤在形态上也相似，且具有相似的折射率分布特征。
人工皮肤是真实人类皮肤的可靠模型，例如在通透性研究中，因为它具有与真实皮肤相似的pH梯度、相似的形态和相似的折射率分布。
