L'Oréal Research and Innovation, 1 Avenue Eugène Schueller, BP22, 93601, Aulnay-sous-Bois, France.
MINES ParisTech-PSL Research University, Fontainebleau, France.
Sci Rep. 2022 Sep 1;12(1):14863. doi: 10.1038/s41598-022-18657-z.
Quantifying skin aging changes and characterizing its 3D structure and function in a non-invasive way is still a challenging area of research, constantly evolving with the development of imaging methods and image analysis tools. In vivo multiphoton imaging offers means to assess skin constituents in 3D, however prior skin aging studies mostly focused on 2D analyses of dermal fibers through their signals' intensities or densities. In this work, we designed and implemented multiphoton multiparametric 3D quantification tools for in vivo human skin pigmentation and aging characterization. We first demonstrated that despite the limited field of view of the technic, investigation of 2 regions of interest (ROIs) per zone per volunteer is a good compromise in assessing 3D skin constituents in both epidermis and superficial dermis. We then characterized skin aging on different UV exposed areas-ventral and dorsal forearms, face. The three major facts of aging that are epidermal atrophy, the dermal-epidermal junction (DEJ) flattening and dermal elastosis can be non-invasively quantified and compared. Epidermal morphological changes occur late and were only objectified between extreme age groups. Melanin accumulation in suprabasal layers with age and chronic exposure on ventral and dorsal forearms is less known and appears earlier. Superficial dermal aging changes are mainly elastin density increase, with no obvious change in collagen density, reflected by SHGto2PEF ratio and SAAID index decrease and ImbrN index increase on all skin areas. Analysis of the z-dermal distribution of these parameters highlighted the 2nd 20 µm thickness normalized dermal sub-layer, that follows the DEJ shape, as exhibiting the highest aging differences. Moreover, the 3D ImbrN index allows refining the share of photoaging in global aging on face and the 3D SAAID index on forearm, which elastin or fibrillar collagens densities alone do not allow. Photoaging of the temple area evolves as a function of chronic exposure with a more pronounced increase in elastin density, also structurally modified from thin and straight elastic fibers in young volunteers to dense and compact pattern in older ones. More generally, multiphoton multiparametric 3D skin quantification offers rich spatial information of interest in assessing normal human skin condition and its pathological, external environment or product induced changes.
定量评估皮肤衰老变化并以非侵入性的方式对其 3D 结构和功能进行特征描述仍然是一个具有挑战性的研究领域，随着成像方法和图像分析工具的发展不断演进。体内多光子成像提供了评估 3D 皮肤成分的手段，然而，先前的皮肤衰老研究主要集中在通过真皮纤维信号的强度或密度对其进行 2D 分析。在这项工作中，我们设计并实施了用于体内人类皮肤色素沉着和衰老特征描述的多光子多参数 3D 定量工具。我们首先证明，尽管该技术的视场有限，但对每个志愿者每个区域的 2 个感兴趣区域（ROI）进行研究是评估表皮和浅层真皮中 3D 皮肤成分的一个很好的折衷方案。然后，我们在不同的紫外线暴露区域（前臂腹侧和背侧、面部）对皮肤衰老进行了特征描述。可以非侵入性地定量和比较衰老的三个主要事实，即表皮萎缩、表皮-真皮交界处（DEJ）变平以及真皮弹性组织减少。表皮形态学变化发生较晚，仅在极端年龄组之间客观化。随年龄增加以及在腹侧和背侧前臂的慢性暴露下，基底层以上各层黑色素的积累不太为人所知，且出现较早。浅层真皮老化变化主要表现为弹性蛋白密度增加，而 SHG 与 2PEF 比值和 SAAID 指数降低以及所有皮肤区域的 ImbrN 指数增加表明，胶原密度没有明显变化。对这些参数的 z-真皮分布进行分析，突出了 20µm 厚的第二层真皮亚层，该亚层跟随 DEJ 的形状，表现出最高的老化差异。此外，3D ImbrN 指数可以细化面部整体老化中光老化的份额，3D SAAID 指数可以细化前臂的光老化份额，而这单凭弹性蛋白或纤维状胶原蛋白密度是无法做到的。太阳穴区域的光老化随慢性暴露而演变，其弹性蛋白密度的增加更为明显，而且在年轻志愿者中，弹性纤维纤细且笔直，在年龄较大的志愿者中则结构上变得密集而紧凑。更一般地说，多光子多参数 3D 皮肤定量提供了丰富的空间信息，这些信息在评估正常人类皮肤状况及其病理、外部环境或产品诱导的变化方面具有重要意义。
