Mokrzynski Krystian, Wojtala Mateusz, Sulkowski Maciej, Ito Shosuke, Wakamatsu Kazumasa, Zadlo Andrzej, Majka Marcin, Sarna Tadeusz, Sarna Michal
Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland.
Doctoral School of Exact and Natural Sciences, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow, Poland.
Int J Mol Sci. 2025 Apr 26;26(9):4119. doi: 10.3390/ijms26094119.
Although melanin is viewed as a natural sunscreen that protects pigmented cells against the adverse effects of solar radiation, recent studies have demonstrated that, under certain conditions, the pigment can actually contribute to light-induced oxidative damage of the cells. However, the main issue with such studies is finding natural pigments without photooxidative modifications. Recently, melanin obtained from melanocytes, generated from human induced pluripotent stem cells (hiPSC-Mel), was suggested as a promising source of the pigment without significant photooxidation. Although different studies have demonstrated the feasibility of the above-mentioned technique to obtain melanin-producing cells, no thorough analysis of the physicochemical properties of the pigment has been performed. To address this issue, we examined the key physicochemical parameters, including the aerobic photoreactivity of melanin isolated from hiPSC-Mel and compared them with those of melanin from other known sources of the pigment, such as bovine retinal pigment epithelium (bRPE) and phototype V (PT-V) hair. Electron paramagnetic resonance (EPR) spectroscopy, dynamic light scattering, UV-Vis absorption and HPLC analysis of melanin degradation products were used. The ability of the examined melanins to photogenerate reactive oxygen species was determined by employing EPR oximetry, EPR spin-trapping and time-resolved singlet oxygen phosphorescence. Although the results of such measurements demonstrated that melanin obtained from hiPSC-Mel exhibited the physicochemical properties typical for eumelanin, a contribution from pheomelanin with a substantial presence of benzothiazine subunits, was also evident. Importantly, the hiPSC-Mel pigment had significantly lower photoreactivity compared to bRPE melanin and PT-V hair melanin. Our findings indicate that hiPSC-Mel could be an excellent source of high-quality pigment for photoprotection studies.
尽管黑色素被视为一种天然的防晒剂，可保护色素细胞免受太阳辐射的不利影响，但最近的研究表明，在某些条件下，这种色素实际上会导致细胞的光诱导氧化损伤。然而，此类研究的主要问题是找到未发生光氧化修饰的天然色素。最近，有人提出从人类诱导多能干细胞产生的黑素细胞中获得的黑色素（hiPSC-Mel）是一种很有前景的色素来源，且不会发生明显的光氧化。尽管不同的研究已经证明了上述获得产生黑色素细胞技术的可行性，但尚未对该色素的物理化学性质进行全面分析。为了解决这个问题，我们检测了关键的物理化学参数，包括从hiPSC-Mel中分离出的黑色素的有氧光反应性，并将其与来自其他已知色素来源（如牛视网膜色素上皮（bRPE）和V型光皮肤（PT-V）毛发）的黑色素进行比较。使用了电子顺磁共振（EPR）光谱、动态光散射、紫外-可见吸收和黑色素降解产物的HPLC分析。通过采用EPR血氧测定法、EPR自旋捕获和时间分辨单线态氧磷光来测定所检测黑色素产生活性氧的能力。尽管这些测量结果表明，从hiPSC-Mel中获得的黑色素表现出真黑色素典型的物理化学性质，但也明显存在大量苯并噻嗪亚基的褐黑素的贡献。重要的是，与bRPE黑色素和PT-V毛发黑色素相比，hiPSC-Mel色素的光反应性显著降低。我们的研究结果表明，hiPSC-Mel可能是用于光保护研究的优质色素的极佳来源。
