Stem cell therapy holds promise for treatment of intractable diseases and injured organs. For clinical translation, it is pivotal to understand the homing, engraftment, and differentiation processes of stem cells in a living body. Here we report near-infrared (NIR) fluorescent semiconductor polymer dots (Pdots) for bright labeling and tracking of human mesenchymal stem cells (MSCs). The Pdots exhibit narrow-band emission at 775 nm with a quantum yield of 22%, among the highest value for various NIR probes. The Pdots together with a cell penetrating peptide are able to track stem cells over two weeks without disturbing their multipotent properties, as confirmed by the analyses on cell proliferation, differentiation, stem-cell markers, and immunophenotyping. The in vivo cell tracking was demonstrated in a liver-resection mouse model, which indicated that the Pdot-labeled MSCs after tail-vein transplantation were initially trapped in lung, gradually migrated to the injured liver, and then proliferated into cell clusters. Liver-function analysis and histological examination revealed that the inflammation induced by liver resection was apparently decreased after stem cell transplantation. With the bright labeling, superior biocompatibility, and long-term tracking performance, the Pdot probes are promising for stem cell research and regenerative medicine.

中文翻译：

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明亮的聚合物点跟踪干细胞植入和迁移到受伤的小鼠肝。

干细胞疗法有望用于治疗顽固性疾病和受损器官。对于临床翻译，了解活细胞中干细胞的归巢，植入和分化过程至关重要。在这里，我们报告近红外（NIR）荧光半导体聚合物点（Pdots）用于人间充质干细胞（MSCs）的明亮标记和跟踪。Pdot在775 nm处显示窄带发射，量子产率为22％，是各种NIR探针的最高值。通过对细胞增殖，分化，干细胞标记和免疫表型的分析证实，Pdot与细胞穿透肽能够在两周内追踪干细胞而不会干扰其多能性。在肝切除小鼠模型中证实了体内细胞追踪，这表明尾静脉移植后，Pdot标记的MSC最初被困在肺中，逐渐迁移到受伤的肝脏，然后增殖成细胞簇。肝功能分析和组织学检查显示，干细胞移植后肝切除引起的炎症明显减轻。Pdot探针具有鲜明的标记，卓越的生物相容性和长期跟踪性能，有望用于干细胞研究和再生医学。肝功能分析和组织学检查显示，干细胞移植后肝切除引起的炎症明显减轻。Pdot探针具有鲜明的标记，卓越的生物相容性和长期跟踪性能，有望用于干细胞研究和再生医学。肝功能分析和组织学检查显示，干细胞移植后肝切除引起的炎症明显减轻。Pdot探针具有鲜明的标记，卓越的生物相容性和长期跟踪性能，有望用于干细胞研究和再生医学。