The development of solar lentigines (SLs) is related to chronic ultraviolet exposure-induced cell senescence. We have previously demonstrated that basal keratinocyte enlargement is a morphological hallmark of skin senescence correlated to the process of skin aging, while clinical studies on the long-term monitoring of the cellular morphological changes in SLs after laser treatment are lacking. In this study, we have developed the harmonic generation microscopy (HGM) for in vivo monitoring the height of basal keratinocytes (HBK) and had administered Q-switched ruby laser or picosecond 532-nm Nd:YAG laser treatment on each side of the face of 25 Asian patients with facial SLs, respectively. In vivo HGM imaging was conducted to longitudinally analyze HBK and the horizontal cell size (HCS). Before treatment, the HBK was significantly higher in the SLs lesional area than that in the adjacent normal region, whereas there was no significant difference in the HCS. After treatment, the lesional HBK remained significantly higher than normal skin regardless of the laser treatment used. Our study indicates that the basal keratinocytes remain abnormal after laser treatment and demonstrates the capability of in vivo HGM for longitudinal, quantitative monitoring of cell senescence and therapeutic effect in SLs.

中文翻译：

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用于监测激光脱色治疗后太阳色斑中基底角质形成细胞高度的体内谐波发生显微镜

太阳色斑（SLs）的发展与慢性紫外线暴露诱导的细胞衰老有关。我们之前已经证明基底角质形成细胞增大是与皮肤老化过程相关的皮肤衰老的形态学标志，而缺乏对激光治疗后 SL 细胞形态学变化的长期监测的临床研究。在这项研究中，我们开发了谐波发生显微镜 (HGM) 用于体内监测基底角质形成细胞 (HBK) 的高度，并在面部两侧进行了 Q 开关红宝石激光或皮秒 532 纳米 Nd:YAG 激光治疗分别来自 25 名面部 SL 的亚洲患者。体内进行 HGM 成像以纵向分析 HBK 和水平细胞大小 (HCS)。治疗前SLs病变区HBK明显高于邻近正常区，而HCS无显着差异。治疗后，无论使用何种激光治疗，病变 HBK 仍显着高于正常皮肤。我们的研究表明，基底角质形成细胞在激光治疗后仍保持异常，并证明了体内HGM 对 SL 中细胞衰老和治疗效果进行纵向、定量监测的能力。