Engineered LINC MIR503HG-loaded extracellular vesicles maintain stemness and pluripotency during long-term hiPSCs culture

The reduction of stemness and pluripotency during the prolonged culture of hiPSCs poses a significant challenge in regenerative medicine. This study identified LINC MIR503HG as a factor involved in maintaining hiPSCs stemness. Consequently, it developed a highly efficient delivery system based on ADSC-EVs, named MIR503HG-EVs, to optimize the culture strategy for hiPSCs. During the extended culture, MIR503HG-EV-treated hiPSCs developed into colonies with more compact morphology, an increased percentage of viable cells, as well as elevated OCT4, SOX2, and NANOG expression. Furthermore, these cells maintained their chromosomal integrity, as no karyotypic anomalies were detected. Mechanistic studies demonstrated that MIR503HG selectively bound AHCTF1 to facilitate the active nucleocytoplasmic transport of MYC mRNA. This resulted in significantly augmented MYC protein production, which activated the stemness regulatory network. Concurrently, MIR503HG-EVs mitigated the decline in differentiation potential of hiPSCs after several passages by modulating the chromatin accessibility of stemness transcription factors and modifying energy metabolism, including glycolysis and oxidative phosphorylation pathways. Moreover, treatment with MIR503HG-EVs significantly enhanced the differentiation efficiency of high-passage hiPSCs into definitive endoderm, pancreatic, and hepatic lineages, thereby achieving a level of proficiency comparable to that of low-passage clones. Overall, this study identified the addition of MIR503HG-EVs as a convenient, efficient, and safe approach for maintaining high-passage hiPSCs.