Optimization of Synthetic mRNA for Highly Efficient Translation and its Application in the Generation of Endothelial and Hematopoietic Cells from Human and Primate Pluripotent Stem Cells.

Identification of transcription factors that directly convert pluripotent stem cells (PSCs) into endothelial and blood cells and advances in the chemical modifications of messenger RNA (mRNA) offer alternative nucleic acid-based transgene-free approach for scalable production of these cells for drug screening and therapeutic purposes. Here we evaluated the effect of 5' and 3' RNA untranslated regions (UTRs) on translational efficiency of chemically-modified synthetic mRNA (modRNA) in human PSCs and showed that an addition of 5'UTR indeed enhanced protein expression. With the optimized modRNAs expressing ETV2 or ETV2 and GATA2, we are able to produce VE-cadherin+ endothelial cells and CD34+CD43+ hematopoietic progenitors, respectively, from human PSCs as well as non-human primate (NHP) PSCs. Overall, our findings provide valuable information on the design of in vitro transcription templates being used in PSCs and its broad applicability for basic research, disease modeling, and regenerative medicine.