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Introduction: The timely delivery of healthcare is an important quality indicator that has been shown to correlate with outcomes for cancer patients. We present our single-institution experience with the development of a same day access scheduling initiative. Methods and Materials: From March 2021 to August 2022, all patients referred for new consultation to a tertiary care-based radiation oncology department were offered same day appointments as part of a prospective pilot initiative. The timespan of this analysis was categorized into 2 successive periods over 36 months—a 18-month pre-initiative period (September 2019 to February 2021) and another subsequent one (March 2021 to August 2022). Descriptive statistics were used to study the impact of this initiative on access-related benchmarks. Results: A total of 2890 patients were referred. Among the 2107 patients scheduled, three hundred and sixteen (15%) opted for same day appointments. Black, Latino, and Asian patients were significantly more likely to use same day access versus Caucasian patients (p=0.01). The same day access initiative increased the proportion of patients seen within 5 days from referral from 23% to 58% (pConclusions: A significant proportion of patients elected for same day appointments illustrating the high demand for expedient delivery of care. The implementation of this same day access initiative was not only feasible but enhanced operational efficiency and practice performance in the outpatient setting.

Multiple genetic association studies have correlated a common allelic block linked to the BAG3 gene with a decreased incidence of heart failure, but the molecular mechanism for such protection remains elusive. One of the variants in this allele block is coding, changing cysteine to arginine at position 151 of BAG3 (rs2234962-BAG3C151R). Here, we use induced pluripotent stem cells (iPSC) to test if the BAG3C151Rvariant alters protein and cellular function in human cardiac myocytes. Quantitative protein interaction network analysis identified specific changes in BAG3C151Rprotein interaction partners in cardiomyocytes but not in iPSCs or an immortalized cell line. Knockdown of BAG3 interacting factors in cardiomyocytes followed by myofibrillar analysis revealed that BAG3C151Rassociates more strongly with proteins involved in the maintenance of myofibrillar integrity. Finally, we demonstrate that cardiomyocytes expressing the BAG3C151Rvariant have improved response to proteotoxic stress in an allele dose-dependent manner. This study suggests that the BAG3C151Rvariant increases cardiomyocyte protection from stress by enhancing the recruitment of factors critical to the maintenance of myofibril integrity, hinting that this variant could be responsible for the cardioprotective effect of the haplotype block. By revealing specific changes in preferential binding partners of the BAG3C151Rprotein variant, we also identify potential targets for the development of novel cardioprotective therapies.

Developing technologies for efficient and scalable disruption of gene expression will provide powerful tools for studying gene function, developmental pathways, and disease mechanisms. Here, we develop clustered regularly interspaced short palindromic repeat interference (CRISPRi) to repress gene expression in human induced pluripotent stem cells (iPSCs). CRISPRi, in which a doxycycline-inducible deactivated Cas9 is fused to a KRAB repression domain, can specifically and reversibly inhibit gene expression in iPSCs and iPSC-derived cardiac progenitors, cardiomyocytes, and T lymphocytes. This gene repression system is tunable and has the potential to silence single alleles. Compared with CRISPR nuclease (CRISPRn), CRISPRi gene repression is more efficient and homogenous across cell populations. The CRISPRi system in iPSCs provides a powerful platform to perform genome-scale screens in a wide range of iPSC-derived cell types, dissect developmental pathways, and model disease.

Molecular chaperones regulate quality control in the human proteome, pathways that have been implicated in many diseases, including heart failure. Mutations in the BAG3 gene, which encodes a co-chaperone protein, have been associated with heart failure due to both inherited and sporadic dilated cardiomyopathy. Familial BAG3 mutations are autosomal dominant and frequently cause truncation of the coding sequence, suggesting a heterozygous loss-of-function mechanism. However, heterozygous knockout of the murine BAG3 gene did not cause a detectable phenotype. To model BAG3 cardiomyopathy in a human system, we generated an isogenic series of human induced pluripotent stem cells (iPSCs) with loss-of-function mutations in BAG3. Heterozygous BAG3 mutations reduced protein expression, disrupted myofibril structure, and compromised contractile function in iPSC-derived cardiomyocytes (iPS-CMs). BAG3-deficient iPS-CMs were particularly sensitive to further myofibril disruption and contractile dysfunction upon exposure to proteasome inhibitors known to cause cardiotoxicity. We performed affinity tagging of the endogenous BAG3 protein and mass spectrometry proteomics to further define the cardioprotective chaperone complex that BAG3 coordinates in the human heart. Our results establish a model for evaluating protein quality control pathways in human cardiomyocytes and their potential as therapeutic targets and susceptibility factors for cardiac drug toxicity.

Tissue engineering approaches have the potential to increase the physiologic relevance of human iPS-derived cells, such as cardiomyocytes (iPS-CM). However, forming Engineered Heart Muscle (EHM) typically requires >1 million cells per tissue. Existing miniaturization strategies involve complex approaches not amenable to mass production, limiting the ability to use EHM for iPS-based disease modeling and drug screening. Micro-scale cardiospheres are easily produced, but do not facilitate assembly of elongated muscle or direct force measurements. Here we describe an approach that combines features of EHM and cardiospheres: Micro-Heart Muscle (μHM) arrays, in which elongated muscle fibers are formed in an easily fabricated template, with as few as 2,000 iPS-CM per individual tissue. Within μHM, iPS-CM exhibit uniaxial contractility and alignment, robust sarcomere assembly and reduced variability and hypersensitivity in drug responsiveness, compared to monolayers with the same cellular composition. μHM mounted onto standard force measurement apparatus exhibited a robust Frank-Starling response to external stretch and a dose-dependent inotropic response to the β-adrenergic agonist isoproterenol. Based on the ease of fabrication, the potential for mass production and the small number of cells required to form μHM, this system provides a potentially powerful tool to study cardiomyocyte maturation, disease and cardiotoxicology in vitro.