Engineering organ-specific tissues for therapeutic applications is a grand challenge, requiring the fabrication and maintenance of densely cellular constructs composed of ~108 cells/ml. Organ building blocks (OBBs) composed of patient-specific–induced pluripotent stem cell–derived organoids offer a pathway to achieving tissues with the requisite cellular density, microarchitecture, and function. However, to date, scant attention has been devoted to their assembly into 3D tissue constructs. Here, we report a biomanufacturing method for assembling hundreds of thousands of these OBBs into living matrices with high cellular density into which perfusable vascular channels are introduced via embedded three-dimensional bioprinting. The OBB matrices exhibit the desired self-healing, viscoplastic behavior required for sacrificial writing into functional tissue (SWIFT). As an exemplar, we created a perfusable cardiac tissue that fuses and beats synchronously over a 7-day period. Our SWIFT biomanufacturing method enables the rapid assembly of perfusable patient- and organ-specific tissues at therapeutic scales.

SUMMARY 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.

Human induced pluripotent stem cells (hiPSCs) have revolutionized the field of human disease modeling, with an enormous potential to serve as paradigm shifting platforms for preclinical trials, personalized clinical diagnosis, and drug treatment. In this review, we describe how hiPSCs could transition cardiac healthcare away from simple disease diagnosis to prediction and prevention, bridging the gap between basic and clinical research to bring the best science to every patient.

To date, several methods have been developed to induce alignment in engineered cardiac tissues. [7][8][9][10][11] One common approach is to seed cardiomyocytes onto micro-or nanopatterned surfaces that contain topographical cues, which guide cellular alignment. [12,13] Another approach is to seed cells onto anisotropic polymer scaffolds [14][15][16] or decellularized matrices [17] that guide tissue alignment. In addition, cell-laden hydrogels seeded into molds of varying geometry can self-assemble into aligned cardiac rods, rings, bundles, and sheets. [18][19][20][21][22][23][24] Unfortunately, these methods are typically confined to thin cardiac tissues (≤100 µm thick) with either linear or radial alignment. By contrast, extrusionbased bioprinting offers broad flexibility to control tissue composition and architecture. Recently, we and others have demonstrated that synthetic and biological fibers exhibit shear-induced alignment during printing, opening the possibility to program tissue alignment via cell templating. [25][26][27][28][29][30][31][32][33][34] However, programming the architecture of human tissues by directly aligning anisotropic tissue building blocks has yet to be explored.Here, we report the fabrication of engineered cardiac tissue with programmable alignment via bioprinting of anisotropic organ building blocks (aOBBs) (Figure 1). These aOBBs are elongated microtissues composed of cellular aligned hiPSC-CMs that can be modularly assembled into a printable bioink (Figure 1a). Individual aOBBs within this bioink align along the print path due to the same shear and extensional forces that orient acellular fibers upon extrusion through a tapered nozzle (Figure 1b). [35] Using this method, we fabricated cardiac tissues with high cellular density and programmed alignment across multiple length scales; ranging from individual aOBBs to the sarcomeric machinery that drives their contractile function (Figure 1c). Results and DiscussionThe first step in creating our cardiac bioink is to fabricate scalable micropillar arrays by stereolithography (SLA). These micropillar arrays are used to generate tens of thousands of aOBBs with controlled aspect ratio and cellular composition. After optimizing these parameters, we employed a sequential transfer micromolding process to create a single contiguousThe ability to replicate the 3D myocardial architecture found in human hearts is a grand challenge. Here, the fabrication of aligned cardiac tissues via bioprinting anisotropic organ building blocks (aOBBs) composed of human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) is reported. A bioink composed of contractile cardiac aOBBs is first generated and aligned cardiac tissue sheets with linear, spiral, and chevron features are printed. Next, aligned cardiac macrofilaments are printed, whose contractile force and conduction velocity increase over time and exceed the performance of spheroid-based cardiac tissues. Finally, the ability to spatially control the magnitude and direction of contractile force...

Serum theophylline concentrations after intravenous administration of a new short-term infusion (Euphyllin Kurzzeitinfusion) were measured in 50 out-patients with chronic obstructive airways disease (COAD). An intravenous infusion of theophylline ethylenediamine 480 mg (corresponding to approximately 350 mg anhydrous theophylline) in 50 ml isotonic solution was given in 20 min. Blood samples were taken beforehand and 25 to 30 min and 1, 3 and 6 h after starting the infusion. 86% of the patients had a one-hour serum level in he therapeutic range of 8.20 mg/l, and 2 h later, this was true of 64% of the patients. The short-term infusion was well tolerated, even in cases with unknown high pre-infusion serum levels. Pertinent pharmacokinetic parameters were determined, such as total body clearance, apparent volume of distribution, and half-life of elimination. Geometric mean an 95%-confidence limits, derived from the log-normal distribution of these parameters, were: Cl = 0.044 (0.018-0.190) l/h/kg ideal body weight, Vd = 0.451 (0.258-0.789) l/kg ideal body weight, and t 1/2(el) = 7.1 (2.6-19.1) h.

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The plasma theophylline concentration gradually increases after oral administration of Euphyllin retard, followed by a slower fall, than is the case after Euphyllin tablets have been taken, in which case maximal theophylline levels are reached 1 1/2 hours after administration. When Euphyllin retard is given, one to two tablets (350-700 mg) eight or twelve hours apart, there is a progressive rise of theophylline plasma levels to a plateau. This plateau can be maintained and is dependent upon dosage and the half-life of theophylline, which varies amongst individuals. Patients with obstructive airway disease treated with one tablet of Euphyllin retard every twelve hours for several weeks had a mean plasma theophylline level of about 6 microng/ml. In these patients the airway resistance, measured by body-plethysmography, improved by about 30%, without any side-effects. Six and twelve hours after administration of two tablets of Euphyllin retard the mean plasma concentration was 13 and 9 microng/ml, respectively. About half the patients receiving the larger dose of two tablets every twelve hours had gastro-intestinal or CNS disturbances. Long-term administration of Euphyllin retard provides a constant blood level of the drug.