Comparison of Non-human Primate versus Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes for Treatment of Myocardial Infarction

Abstract

Non-human primates (NHPs) can serve as a human-like model to study cell therapy using induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). However, whether the efficacy of NHP and human iPSC-CMs is mechanistically similar remains unknown. To examine this, RNU rats received intramyocardial injection of 1 × 10⁷ NHP or human iPSC-CMs or the same number of respective fibroblasts or PBS control (n = 9-14/group) at 4 days after 60-min coronary artery occlusion-reperfusion. Cardiac function and left ventricular remodeling were similarly improved in both iPSC-CM-treated groups. To mimic the ischemic environment in the infarcted heart, both cultured NHP and human iPSC-CMs underwent 24-hr hypoxia in vitro. Both cells and media were collected, and similarities in transcriptomic as well as metabolomic profiles were noted between both groups. In conclusion, both NHP and human iPSC-CMs confer similar cardioprotection in a rodent myocardial infarction model through relatively similar mechanisms via promotion of cell survival, angiogenesis, and inhibition of hypertrophy and fibrosis.

Keywords: RNA-seq; iPSC-CM; metabolomics; myocardial infarction; non-human primate.

Figure 1

Cardiac Function Assessment after Cell Injection Echocardiography was monitored at 1 day before cell injection, and 2 weeks and 4 weeks after cell injection. (A and B) LV ejection fraction (A) and fractional shortening (B) were improved significantly in both NHP and human iPSC-CM groups compared with the PBS group. (C) LV end-diastolic volume was markedly dilated in the PBS control, NHP fibroblast, and human fibroblast groups compared with both NHP and human iPSC-CM groups. (D) LV end-systolic volume was increased in the PBS control, NHP fibroblast, and human fibroblast groups but decreased in both NHP and human iPSC-CM groups (n = 14 independent experiments). Hemodynamics was analyzed using pressure-volume Millar catheter. (E) Examples of changes in pressure-volume relationships during inferior vena cava occlusion. (F) Slope of end-systolic pressure-volume relationship (ESPVR) showed significantly preserved cardiac contractility in both NHP and human iPSC-CM groups. PBS, n = 7; NHP fibroblast, n = 9; NHP iPSC-CM, n = 11; human fibroblast, n = 9; human iPSC-CM, n = 12 independent experiments. Data are presented as mean ± SEM. ^∗∗p < 0.01, NHP iPSC-CM versus NHP fibroblast; ^##p < 0.01, NHP iPSC-CM versus PBS; ^†p < 0.05, ^††p < 0.01, human iPSC-CM versus human fibroblast; ^‡‡p < 0.01, human iPSC-CM versus PBS; by one-way ANOVA.

Figure 2

Graft and Scar Size Assessment at 4 Weeks after Myocardial Infarction (A) Examples of viable graft in the ischemic zone. Both NHP and human iPSC-CMs were identified with non-specific cardiac troponin T and human specific mitochondria at 4× magnification. (B) Viable grafts in both groups of iPSC-CM-treated hearts were observed under 63× magnification. (C) Representative pictures of infarcted left ventricle with trichrome staining. PBS and fibroblast control groups showed more transmural infarction than iPSC-CM-treated groups, which had more viable myocardium. (D) The amount of viable myocardium was quantified within the ischemic zone and presented as a percentage of the area of ischemic zone. (E) Scar size, presented as a percentage of fibrotic tissue to whole myocardial area, was compared among PBS and cell-treated groups. PBS, n = 5; NHP fibroblast, n = 6; NHP iPSC-CM, n = 6; human fibroblast, n = 6; human iPSC-CM, n = 6 independent experiments. Data are presented as mean ± SEM. ^∗p < 0.05, ^∗∗p < 0.01, NHP iPSC-CM versus NHP fibroblast; ^#p < 0.05, ^##p < 0.01, NHP iPSC-CM versus PBS; ^††p < 0.01, human iPSC-CM versus human fibroblast; ^‡‡p < 0.01, human iPSC-CM versus PBS.

Figure 3

Myocardial Remodeling Was Compared at Histological Level at Border Zone and Remote Zone to the Infarct (A) Cardiomyocyte size was compared among PBS, NHP fibroblast, NHP iPSC-CM, human fibroblast, and human iPSC-CM groups. (B) Examples of wheat germ agglutinin staining showing the size of endogenous mouse cardiomyocytes of the three groups. (C) Fibrosis was quantified as the percentage of interstitial collagen deposition. (D) Representative images of Picro-Sirius red staining showing interstitial fibrosis of the three groups. (E) Capillary density was quantified as absolute number of capillaries per unit area. (F) Representative CD144 staining showing capillaries. PBS, n = 5; NHP fibroblast, n = 6; NHP iPSC-CM, n = 6; human fibroblast, n = 6; human iPSC-CM, n = 6 independent experiments. Data are presented as mean ± SEM. ^∗p < 0.05, ^∗∗p < 0.01, NHP iPSC-CM versus NHP fibroblast; ^#p < 0.05, ^##p < 0.01, NHP iPSC-CM versus PBS; ^†p < 0.05, ^††p < 0.01, human iPSC-CM versus human fibroblast; ^‡p < 0.05, ^‡‡p < 0.01 human iPSC-CM versus PBS.

Figure 4

RNA-Seq Analysis of Both NHP and Human iPSC-CMs in Response to 24-hr Oxygen Depletion (A) The numbers of significantly regulated genes (p < 0.05) and the significant biological function of the common genes in both groups are listed. (B) Fold change of VEGF gene in hypoxic iPSC-CMs from both species. (C) Fold change of VEGF in culture medium using proteomic angiogenesis assay. n = 3 independent experiments. Data are presented as mean ± SEM. ^∗∗p < 0.01.

Figure 5

Comparison of Biological Function Revealed by RNA-Seq Analysis between NHP and Human iPSC-CMs after 24-hr Hypoxia (A) Common biological functions of the genes. (B) Biological functions that are regulated toward opposite directions. n = 3 independent experiments.

Figure 6

Metabolomic Analysis of the Culture Media in Response to 24-hr Hypoxia (A) Heatmap generated from metabolomic analysis. Relative expression values (log ratios versus normoxic condition) were used. (B) Volcano plot of the total and top regulated (p < 0.05) metabolites seen in NHP iPSC-CMs. (C) Volcano plot of the total and top regulated (p < 0.05) metabolites seen in human iPSC-CMs. (D) Comparison of the metabolites changed more than 2-fold between the two species. n = 3 independent experiments.