AHA Scientific Sessions 2026 Abstract · Nov 2, 2026
SALL4 Synergistically Amplifies ETV2-Mediated Endothelial Reprogramming and Promotes Therapeutic Revascularization
By Choi YG
Background: Ischemic heart disease is a leading cause of death worldwide, and revascularization strategies have therapeutic limitations. ETV2 is a master regulator and pioneer factor of endothelial specification that can directly reprogram fibroblasts into endothelial cells. Reprogramming efficiency remains low, however, limiting therapeutic translation in vivo . Hypothesis: We hypothesized that lineage-specific transcriptional cofactors synergistically improve ETV2-mediated endothelial reprogramming and promote vasculogenesis. Methods: Candidate cofactors were screened using computational analysis of single-cell RNA sequencing databases from developing mouse embryos, embryoid bodies, and embryonic fibroblasts (MEFs). Secondary analyses of highly ranked candidates used retroviral co-transduction with ETV2 in MEFs, and reprogramming efficiency was quantified by flow cytometry at days 2 and 7. Transcriptional identity was profiled by scRNA-seq of MEFs transduced with empty vector, ETV2, or ETV2 plus selected cofactors. Results: Computational screening identified SALL4 as an ideal candidate cofactor. Co-expression of SALL4 with ETV2 increased the reprogramming rate at day 2 (ETV2 alone: 26.03% vs. ETV2 plus SALL4: 37.54%; p < 0.0001), and this synergistic effect increased by day 7 (22.54% vs. 43.36%; p < 0.0001). Single cell RNA-seq revealed that ETV2 plus SALL4 transduction formed clusters distinct from ETV2 alone and showed enriched expression of endothelial maturation markers, including Pecam1 , Nos3 , and Vwf . The transcription factor Hand1 was specifically induced by ETV2 plus SALL4, defining a regulatory program not activated by either factor alone. The SALL4-mediated mechanism was defined using mutagenesis whereby a SALL4 deletional mutant lacking the cluster 4 zinc finger domain (SALL4 αZF4) significantly attenuated the impact on ETV2-mediated reprogramming. Furthermore, our mechanistic studies demonstrated that the retroviral knockdown of Chd4 , which impacts NuRD-dependent chromatin remodeling, also abolished the SALL4-mediated synergy for ETV2-mediated reprogramming. Conclusions: SALL4 is a transcriptional cofactor that synergistically enhances ETV2-mediated endothelial reprogramming and drives a distinct endothelial maturation program. These findings support the notion that cofactor-augmented ETV2-mediated reprogramming can be used for regenerative vascularization for ischemic heart disease and other ischemic vascular disorders.