Doctor of Medicine, Unlisted School (2002)
Doctor of Philosophy, Chinese Academy Of Sciences (2011)
Joseph Wu, Postdoctoral Faculty Sponsor
Idiopathic or heritable pulmonary arterial hypertension is characterized by loss and obliteration of lung vasculature. Endothelial cell dysfunction is pivotal to the pathophysiology but different causal mechanisms may reflect a need for patient-tailored therapies.Endothelial cells differentiated from induced pluripotent stem cells were compared to pulmonary arterial endothelial cells from the same patients with idiopathic or heritable pulmonary arterial hypertension, to determine whether they shared functional abnormalities and altered gene expression patterns, that differed from those in unused donor cells. We then investigated whether endothelial cells differentiated from pluripotent cells could serve as surrogates to test emerging therapies.Functional changes assessed included adhesion, migration, tube formation, and propensity to apoptosis. Expression of BMPR2 and its target, collagen IV, pSMAD1/5 signaling and transcriptomic profiles were also analyzed.Native pulmonary arterial and induced pluripotent stem cell-derived endothelial cells from idiopathic and heritable pulmonary arterial hypertension patients compared to controls, showed a similar reduction in adhesion, migration, survival, and tube formation, decreased BMPR2 and downstream signaling and collagen IV expression. Transcriptomic profiling revealed high KISS1 related to reduced migration and low CES1, to impaired survival in patient cells. A beneficial angiogenic response to potential therapies, FK-506 and Elafin, was related to reduced SLIT3, an anti-migratory factor.Despite the site of disease in the lung our study indicates that induced pluripotent stem cell derived endothelial cells are useful surrogates to uncover novel features related to disease mechanisms and to better match patients to therapies.
View details for PubMedID 27779452
Reduced endothelial-pericyte interactions are linked to progressive small vessel loss in pulmonary arterial hypertension (PAH), but the molecular mechanisms underlying this disease remain poorly understood. To identify relevant gene candidates associated with aberrant pericyte behavior, we performed a transcriptome analysis of patient-derived donor control and PAH lung pericytes followed by functional genomics analysis. Compared with donor control cells, PAH pericytes had significant enrichment of genes involved in various metabolic processes, the top hit being PDK4, a gene coding for an enzyme that suppresses mitochondrial activity in favor of glycolysis. Given reports that link reduced mitochondrial activity with increased PAH cell proliferation, we hypothesized that increased PDK4 is associated with PAH pericyte hyperproliferation and reduced endothelial-pericyte interactions. We found that PDK4 gene and protein expression was significantly elevated in PAH pericytes and correlated with reduced mitochondrial metabolism, higher rates of glycolysis, and hyperproliferation. Importantly, reducing PDK4 levels restored mitochondrial metabolism, reduced cell proliferation, and improved endothelial-pericyte interactions. To our knowledge, this is the first study that documents significant differences in gene expression between human donor control and PAH lung pericytes and the link between mitochondrial dysfunction and aberrant endothelial-pericyte interactions in PAH. Comprehensive characterization of these candidate genes could provide novel therapeutic targets to improve endothelial-pericyte interactions and prevent small vessel loss in PAH.
View details for DOI 10.1016/j.ajpath.2016.05.016
View details for PubMedID 27456128
Understanding individual susceptibility to drug-induced cardiotoxicity is key to improving patient safety and preventing drug attrition. Human induced pluripotent stem cells (hiPSCs) enable the study of pharmacological and toxicological responses in patient-specific cardiomyocytes (CMs) and may serve as preclinical platforms for precision medicine. Transcriptome profiling in hiPSC-CMs from seven individuals lacking known cardiovascular disease-associated mutations and in three isogenic human heart tissue and hiPSC-CM pairs showed greater inter-patient variation than intra-patient variation, verifying that reprogramming and differentiation preserve patient-specific gene expression, particularly in metabolic and stress-response genes. Transcriptome-based toxicology analysis predicted and risk-stratified patient-specific susceptibility to cardiotoxicity, and functional assays in hiPSC-CMs using tacrolimus and rosiglitazone, drugs targeting pathways predicted to produce cardiotoxicity, validated inter-patient differential responses. CRISPR/Cas9-mediated pathway correction prevented drug-induced cardiotoxicity. Our data suggest that hiPSC-CMs can be used in vitro to predict and validate patient-specific drug safety and efficacy, potentially enabling future clinical approaches to precision medicine.
View details for DOI 10.1016/j.stem.2016.07.006
View details for PubMedID 27545504
Human induced pluripotent stem cells (iPSCs) can be derived from various types of somatic cells by transient overexpression of 4 Yamanaka factors (OCT4, SOX2, C-MYC, and KLF4). Patient-specific iPSC derivatives (e.g., neuronal, cardiac, hepatic, muscular, and endothelial cells [ECs]) hold great promise in drug discovery and regenerative medicine. In this study, we aimed to evaluate whether the cellular origin can affect the differentiation, in vivo behavior, and single-cell gene expression signatures of human iPSC-derived ECs. We derived human iPSCs from 3 types of somatic cells of the same individuals: fibroblasts (FB-iPSCs), ECs (EC-iPSCs), and cardiac progenitor cells (CPC-iPSCs). We then differentiated them into ECs by sequential administration of Activin, BMP4, bFGF, and VEGF. EC-iPSCs at early passage (10 < P < 20) showed higher EC differentiation propensity and gene expression of EC-specific markers (PECAM1 and NOS3) than FB-iPSCs and CPC-iPSCs. In vivo transplanted EC-iPSC-ECs were recovered with a higher percentage of CD31(+) population and expressed higher EC-specific gene expression markers (PECAM1, KDR, and ICAM) as revealed by microfluidic single-cell quantitative PCR (qPCR). In vitro EC-iPSC-ECs maintained a higher CD31(+) population than FB-iPSC-ECs and CPC-iPSC-ECs with long-term culturing and passaging. These results indicate that cellular origin may influence lineage differentiation propensity of human iPSCs; hence, the somatic memory carried by early passage iPSCs should be carefully considered before clinical translation.
View details for PubMedID 27398408