Degeneration of photoreceptors is a major cause of blindness. Identifying new methods for the generation of photoreceptors offers valuable options for a cell replacement therapy of blindness. Here, we show that primary adult human retinal pigmented epithelium (hRPE) cells were directly converted to postmitotic neurons with various properties of photoreceptors by the neurogenic transcription factor ASCL1 and microRNA124. At Day 8 after the induction of ASCL1 and miRNA124 expression in hRPE cells, 91% of all cells were Tuj1⁺, and 83% of all cells were MAP2⁺ neurons. The cone photoreceptor marker L/M-opsin, the rod photoreceptor marker rhodopsin, and the generic photoreceptor marker recoverin were expressed in 76%, 86%, and 92% of all cells, respectively. Real-time quantitative PCR measurements showed significant and continuous increases in the expression of photoreceptor markers phosducin and recoverin, rod cell markers phosphodiesterases 6 b and arrestin S-antigen, and cone cell markers L/M-opsin and S-opsin in three independent lines of primary hRPE cells at different days of transdifferentiation. Transmission electron microscopy of converted neurons showed disc-like structures similar to those found in photoreceptors. While the converted neurons had voltage-dependent Na⁺, K⁺, and Ca²⁺ currents, light-induced change in membrane potential was not detected. The study demonstrates the feasibility of rapid and efficient transdifferentiation of adult hPRE cells to neurons with many properties of photoreceptors. It opens up a new possibility in cell replacement therapy of blindness caused by photoreceptor degeneration.

Impact statement

The degeneration of photoreceptors is a leading cause of blindness. Retinal pigment epithelium (RPE) cells are mitotic cells that support the function of photoreceptors. We found that lentivirus-mediated overexpression of ASCL1 and microRNA124 directly converted primary adult human RPE cells to postmitotic neurons with many properties of photoreceptors. This study identifies a new method toward the generation of human photoreceptors and provides a new avenue in cell-based therapies for blindness caused by photoreceptor degeneration.

中文翻译：

---

成人视网膜色素上皮细胞直接转化为具有光感受器特性的神经元

光感受器的退化是导致失明的主要原因。确定产生光感受器的新方法为失明的细胞替代疗法提供了有价值的选择。在这里，我们展示了原代成人视网膜色素上皮 (hRPE) 细胞通过神经源性转录因子 ASCL1 和 microRNA124 直接转化为具有光感受器各种特性的有丝分裂后神经元。在 hRPE 细胞中诱导 ASCL1 和 miRNA124 表达后第 8 天，所有细胞的 91% 为 Tuj1 ⁺，所有细胞的 83% 为 MAP2 ⁺神经元。锥形光感受器标记 L/M-视蛋白、杆状光感受器标记视紫质和通用光感受器标记恢复蛋白分别在所有细胞的 76%、86% 和 92% 中表达。实时定量 PCR 测量显示，三个独立细胞系中光感受器标志物 phosducin 和 recoveryin、视杆细胞标志物磷酸二酯酶 6b 和抑制蛋白 S-抗原以及视锥细胞标志物 L/M-视蛋白和 S-视蛋白的表达显着且持续增加不同转分化天数的原代 hRPE 细胞。转换后的神经元的透射电子显微镜显示出类似于光感受器中发现的盘状结构。而转换后的神经元具有电压依赖性 Na ⁺、K ⁺和 Ca ²⁺电流，未检测到光诱导的膜电位变化。该研究证明了将成人 hPRE 细胞快速有效地转分化为具有光感受器许多特性的神经元的可行性。它为光感受器变性所致失明的细胞替代疗法开辟了新的可能性。

影响陈述

光感受器的退化是导致失明的主要原因。视网膜色素上皮 (RPE) 细胞是支持光感受器功能的有丝分裂细胞。我们发现慢病毒介导的 ASCL1 和 microRNA124 的过度表达直接将原代成人 RPE 细胞转化为具有光感受器许多特性的有丝分裂后神经元。这项研究确定了一种产生人类光感受器的新方法，并为光感受器变性引起的失明提供了基于细胞的疗法的新途径。