PLURIPOTENT STEM CELL-DERIVED CARDIOVASCULAR PROGENITORS DIFFFERENTIATED ON LAMININ 221 REGENERATE AND IMPROVE FUNCTION OF INFARCTED SWINE HEARTS
Authors: Yap Lynn , Chong Li Yen , Tan Clarissa , Adusumalli Swarnaseetha , Seow Millie , Guo Jing , Cai Zuhua , Loo Sze Jie , Lim Eric , Lath Narayan , Ye Lei , Petretto Enrico , Tryggvason Karl 
Published: April 2021

AbstractBackgroundIschemic heart disease is a huge global burden where patients often have irreversibly damaged heart muscle. State-of-the-art technology using stem cell-derived products for cellular therapy could potentially replace damaged heart muscle for regenerative cardiology.Methods and ResultsPluripotent human embryonic stem cells (hESCs) were differentiated on a laminin LN521+221 matrix to cardiovascular progenitors (CVPs). Global transcriptome analyses at multiple time points by single-cell RNA-sequencing demonstrated high reproducibility (R2> 0.95) between two hESCs lines. We identified several CVP signature genes as quality batch control parameters which are highly specific to our CVPs as compared to canonical cardiac progenitor genes. A total of 200 million CVPs were injected into the infarcted region caused by permanent ligation of the coronary arteries of 10 immunosuppressed pigs and maintained for 4- and 12-weeks post transplantation. The transplanted cells engrafted and proliferated in the infarcted area as indicated by IVIS imaging, histology staining and spatial transcriptomic analysis. Spatial transcriptomic analysis at 1 week following transplantation showed that the infarcted region expressed human genes in the same area as immunohistology sections. Heart function was analyzed by magnetic resonance imaging (MRI) and computerized tomography (CT). Functional studies revealed overall improvement in left ventricular ejection fraction by 21.35 ± 3.3 %, which was accompanied by significant improvements in ventricular wall thickness and wall motion, as well as a reduction in infarction size after CVP transplantation as compared to medium control pigs (P < 0.05). Immunohistology analysis revealed maturation of the CVPs to cardiomyocytes (CMs) where the human grafts aligned with host tissue forming end-to-end connections typical for heart muscle. Electrophysiology analyses revealed electric continuity between injected and host tissue CMs. Episodes of ventricular tachyarrhythmia (VT) over a period of 25 days developed in four pigs, one pig had persistent VT, while the rest remained in normal sinus rhythm. All ten pigs survived the experiment without any VT-related death.ConclusionsWe report a highly reproducible, chemically defined and fully humanized differentiation method of hESCs for the generation of potent CVPs. This method may pave the way for lasting stem cell therapy of myocardial infarction (MI) in humans.Clinical PerspectiveWhat is New?We present a highly reproducible, chemically defined and fully humanized laminin-based differentiation method for generation of large amounts of cardiovascular progenitors (CVP); 20 million cells in a 10 cm2culture dish which were used for a preclinical study in pigs.Transplantation of the CVPs into the myocardial infarcted pig hearts yields maturation of the progenitor cells to cardiomyocytes (CMs) and improved cardiac function (21.35 ± 3.3 % LVEF improvement) using only 200 million CVPs.Temporary episodes of ventricular arrhythmia (50%) were observed after CVP transplantation. No fatal ventricular arrhythmia occurred.What are the clinical implications?Our laminin-based approach generated potent CVPsin vivoand largely restored function of the damaged heart.Cardiovascular progenitors may provide a new and safe therapeutic strategy for myocardial infarction.The results may have a significant impact on regenerative cardiology.