The successful derivation of human induced pluripotent stem cells (hiPSCs) by de-differentiation of somatic cells offers significant potential to overcome obstacles in the field of cardiovascular disease. hiPSC derivatives offer incredible potential for new disease models and regenerative medicine therapies. However, many questions remain regarding the optimal starting materials and methods to enable safe, efficient derivation of hiPSCs suitable for clinical applications. Initial reprogramming experiments were carried out using lentiviral or retroviral gene delivery methods. More recently, various non-viral methods that avoid permanent and random transgene insertion have emerged as alternatives. These include transient DNA transfection approaches using transposons or minicircle plasmids, protein transduction approaches, and RNA transfection approaches. In addition, several small molecules have been found to significantly augment iPSC derivation efficiency, allowing the use of a fewer number of genes during pluripotency induction. Here, we review these various methods for the derivation of hiPSCs, focusing on their ultimate clinical applicability, with an emphasis on their potential for use as cardiovascular therapies and disease modeling platforms.

BACKGROUND AND PURPOSE: Hemodynamic features of brain AVMs may portend increased hemorrhage risk. Previous studies have suggested that MTT is shorter in ruptured AVMs as assessed on quantitative color-coded parametric DSA. This study assesses the interrater reliability of MTT measurements obtained using quantitative color-coded DSA.MATERIALS AND METHODS: Thirty-five color-coded parametric DSA images of 34 brain AVMs were analyzed by 4 neuroradiologists with experience in interventional neuroradiology. Hemodynamic features assessed included MTT of the AVM and TTP of the dominant feeding artery and draining vein. Agreement among the 4 raters was assessed using the intraclass correlation coefficient. RESULTS:The interrater reliability among the 4 raters was poor (intraclass correlation coefficient ¼ 0.218; 95% CI, 0.062-0.414; P value ¼ .002) as it related to MTT assessment. When the analysis was limited to cases in which the raters selected the same image to analyze and selected the same primary feeding artery and the same primary draining vein, interrater reliability improved to fair (intraclass correlation coefficient ¼ 0.564; 95% CI, 0.367-0.717; P , .001). CONCLUSIONS:Interrater reliability in deriving color-coded parametric DSA measurements such as MTT is poor so minor differences among raters may result in a large variance in MTT and TTP results, partly due to the sensitivity and 2D nature of the technique. Reliability can be improved by defining a standard projection, feeding artery, and draining vein for analysis.ABBREVIATIONS: AUC ¼ area under the curve; bAVM ¼ brain AVM; cDSA ¼ color-coded parametric quantitative DSA; ICC ¼ intraclass correlation coefficient; IQR ¼ interquartile range; PCA ¼ posterior cerebral artery; SCA ¼ superior cerebellar artery B rain AVMs (bAVMs) are uncommon high-flow vascular mal-

Background and Purpose: The management of unruptured intracranial aneurysms remains controversial. The decisions to treat are heavily informed by estimated risk of bleeding. However, these estimates are imprecise, and better methods for stratifying the risk or tailoring treatment strategy are badly needed. Here, we demonstrate an initial proof-of-principle concept for endovascular biopsy to identify the key molecular pathways and gene expression changes associated with aneurysm formation. We couple this technique with single cell RNA sequencing (scRNAseq) to develop a roadmap of the pathogenic changes of a dolichoectatic vertebrobasilar aneurysm in a patient with polyarteritis nodosa.Methods: Endovascular biopsy and fluorescence activated cell sorting was used to isolate the viable endothelial cells (ECs) using the established techniques. A single cell RNA sequencing (scRNAseq) was then performed on 24 aneurysmal ECs and 23 patient-matched non-aneurysmal ECs. An integrated panel of bioinformatic tools was applied to determine the differential gene expression, enriched signaling pathways, and cell subpopulations hypothesized to drive disease pathogenesis.Results: We identify a subset of 7 (29%) aneurysm-specific ECs with a distinct gene expression signature not found in the patient-matched control ECs. A gene set enrichment analysis identified these ECs to have increased the expression of genes regulating the leukocyte-endothelial cell adhesion, major histocompatibility complex (MHC) class I, T cell receptor recycling, tumor necrosis factor alpha (TNFα) response, and interferon gamma signaling. A histopathologic analysis of a different intracranial aneurysm that was later resected yielded a diagnosis of polyarteritis nodosa and positive staining for TNFα.Conclusions: We demonstrate feasibility of applying scRNAseq to the endovascular biopsy samples and identify a subpopulation of ECs associated with cerebral aneurysm in polyarteritis nodosa. Endovascular biopsy may be a safe method for deriving insight into the disease pathogenesis and tailoring the personalized treatment approaches to intracranial aneurysms.

of PPODA-QT tothe positive controls results in statistically significant reduction of protein depletion from blood samples.Verification of this result via analysis of desorbed proteins is underway. Conclusion The protein-resistance of PPODA-QT as shown in this study makes it an interesting material candidatefor a variety of surgical applications. A liquid-to-solid curing material with inherent protein-resistantproperties could be utilized not only as a novel liquid embolic for treatment of intracranial aneurysmsand AVMs, but could also be used as a non-fouling, bioinert coating for metallic implants such as stents,flow diverters, and coils.