A tissue-engineered scale model of the heart ventricle

Probably not a substantial claim: may not pass S3 (load-bearing).

Animal models and isolated heart preparations are evaluated using pre-clinical and clinical modalities such as catheterization, echocardiography, and MRI.

“animal models and isolated heart preparations are evaluated using pre-clinical and clinical measurement modalities such as catheterization3, echocardiography4, and magnetic resonance imaging5.”

• cites [3] Pacher, P., Nagayama, T., Mukhopadhyay, P., Batkai, S. & Kass, D. A. Measurement of cardiac function using pressure–volume conductance catheter technique in mice and rats. Nat. Protoc. 3, 1422–1434 (2008). sourcePartly supported

  The Introduction describes catheterization to measure cardiac function in mouse and rat animal models, including intact beating hearts. It does not establish the cited technique's use in isolated heart preparations. Citation 3 is attached to catheterization, so the separate echocardiography and MRI citations are not assessed here. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [4] Ram, R., Mickelsen, D. M., Theodoropoulos, C. & Blaxall, B. C. New approaches in small animal echocardiography: imaging the sounds of silence. Am. J. Physiol. Heart Circ. Physiol. 301, H1765–1780 (2011). sourceNot checked — no full text of the source
• cites [5] Bakermans, A. J. et al. Small animal cardiovascular MR imaging and spectroscopy. Prog. Nucl. Magn. Reson. Spectrosc. 88–89, 1–47 (2015). sourceNot checked — no full text of the source

May combine two claims.

Data from animal models allow direct comparison to patient data, but differences in genetics, physiology, and disease etiology limit their utility for developing therapeutic interventions.

“Data obtained using these methods allow direct comparison to patient data, but differences in genetics, physiology and disease etiology limit the utility of animal models for developing therapeutic interventions6,7.”

• cites [6] Chandrasekera, P. C. & Pippin, J. J. The human subject: an integrative animal model for 21st century heart failure research. Am. J. Transl. Res. 7, 1636–1647 (2015).Not checked — no full text of the source
• cites [7] Gloschat, C. R. et al. Arrhythmogenic and metabolic remodelling of failing human heart. J. Physiol. 594, 3963–3980 (2016). sourcePartly supported

  The Introduction says animal models may not reproduce the varied causes of human heart failure and that these differences limit translation to clinical therapies. The Conclusions also identify species and physiological differences as barriers. Our copy does not establish that data obtained using the citing paper’s methods allow direct comparison with patient data, or specifically identify genetic differences between animal models and humans as a barrier. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

May combine two claims.

Myocardial ECM is fibrillar, anisotropic, and provides nanotopographical cues that guide cardiomyocyte alignment and assembly, ultimately forming a helicoid structure that optimizes ejection fraction during ventricular contraction.

“The myocardial ECM is fibrillar, anisotropic, and provides nanotopographical cues that guide cardiomyocyte alignment and assembly44, ultimately forming a helicoid structure that optimizes ejection fraction during ventricular contraction45.”

• cites [44] Kim, D. H. et al. Nanoscale cues regulate the structure and function of macroscopic cardiac tissue constructs. Proc. Natl Acad. Sci. USA 107, 565–570 (2010). sourceSupported
• cites [45] Savadjiev, P. et al. Heart wall myofibers are arranged in minimal surfaces to optimize organ function. Proc. Natl Acad. Sci. USA 109, 9248–9253 (2012). sourceNot checked — no full text of the source

May combine two claims.

Engineered cardiac organoid chambers made of cardiomyocytes in isotropic hydrogels showed promise for intra-ventricular pressure measurements, but lack of scaffold hampers formation of organized tissues recapitulating native myocardial laminar architecture.

“Engineered cardiac organoid chambers comprised of cardiomyocytes embedded in isotropic hydrogels showed significant promise for obtaining intra-ventricular pressure measurements26–29 but the lack of a scaffold to guide cell assembly hampers the formation of organized tissues that recapitulate the laminar architecture30,31 of the native myocardium.”

• cites [26] Lee, E. J., Kim do, E., Azeloglu, E. U. & Costa, K. D. Engineered cardiac organoid chambers: toward a functional biological model ventricle. Tissue Eng. Part A 14, 215–225 (2008). sourceNot checked — no full text of the source
• cites [27] Gonen-Wadmany, M., Gepstein, L. & Seliktar, D. Controlling the cellular organization of tissue-engineered cardiac constructs. Ann. N. Y. Acad. Sci. 1015, 299–311 (2004). sourceNot checked — no full text of the source
• cites [28] Yildirim, Y. et al. Development of a biological ventricular assist device: preliminary data from a small animal model. Circulation 116, I-16–I-23 (2007). sourceNot checked — no full text of the source
• cites [29] Li, R. A. et al. Bioengineering an electro-mechanically functional miniature ventricular heart chamber from human pluripotent stem cells. Biomaterials 163, 116–127 (2018). sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [30] Costa, K. D., Takayama, Y., McCulloch, A. D. & Covell, J. W. Laminar fiber architecture and three-dimensional systolic mechanics in canine ventricular myocardium. Am. J. Physiol. 276, H595–607 (1999). sourceNot checked — no full text of the source
• cites [31] Arts, T., Costa, K. D., Covell, J. W. & McCulloch, A. D. Relating myocardial laminar architecture to shear strain and muscle fiber orientation. Am. J. Physiol. Heart Circ. Physiol. 280, H2222–2229 (2001). sourceNot checked — no full text of the source

May combine two claims.

PCL/gelatin nanofibers are biocompatible, biodegradable, promote cell adhesion, provide sufficient structural integrity for ventricle culture and catheterization, and can be produced by various nanofiber production systems including electrospinning and force-spinning.

“We selected polycaprolactone (PCL)/gelatin nanofibers as our material of choice because they are biocompatible and biodegradable, they promote cell adhesion, provide sufficient structural integrity for ventricle culture and catheterization, and can be produced by a variety of nanofiber production systems that include electrospinning and force-spinning methods40.”

• cites [40] Capulli, A. K., MacQueen, L. A., Sheehy, S. P. & Parker, K. K. Fibrous scaffolds for building hearts and heart parts. Adv. Drug Deliv. Rev. 96, 83–102 (2016). sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

Classified as probably not a substantial claim.

In native heart, overlapping myocardial fibers are arranged into distinct laminae four to six myocytes thick and separated from adjacent laminae by an extracellular collagen network.

“In the native heart, overlapping myocardial fibers are arranged into distinct laminae four to six myocytes thick and separated from adjacent laminae by an extracellular collagen network42.”

• cites [42] Pope, A. J., Sands, G. B., Smaill, B. H. & LeGrice, I. J. Three-dimensional transmural organization of perimysial collagen in the heart. Am. J. Physiol. Heart C 295, 1243–1252 (2008). sourcePartly supported

  The Discussion (3-D perimysial collagen organization; page unavailable) describes branching myocardial layers grouped by perimysial collagen and reports them as approximately four cells thick, not four to six. The Results (page unavailable) show collagen between adjacent layers, but the paper also says laminar structure is not evident in the outer 10–20% of the rat left ventricle, so the claim is too general. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

Cardiomyocyte spontaneous beat rates in our model ventricles were similar to other in vitro assays based on NRVM or hiPSC-CM, showing moderate positive chronotropy (~40% beat rate).

“Cardiomyocyte spontaneous beat rates in our model ventricles were similar to other in vitro assays based on NRVM49 or hiPSC-CM16, showing moderate positive chronotropy (~40% beat rate)10,18.”

• cites [49] Meiry, G. et al. Evolution of action potential propagation and repolarization in cultured neonatal rat ventricular myocytes. J. Cardiovasc. Electrophysiol. 12, 1269–1277 (2001). sourceNot checked — no full text of the source
• cites [16] Mannhardt, I. et al. Human engineered heart tissue: analysis of contractile force. Stem Cell Rep. 7, 29–42 (2016). sourceSupported
• cites [10] Eder, A., Vollert, I., Hansen, A. & Eschenhagen, T. Human engineered heart tissue as a model system for drug testing. Adv. Drug Deliv. Rev. 96, 214–224 (2016). sourceNot checked — no full text of the source

May combine two claims.

Moderate positive chronotropy and reduction of stroke work at high isoproterenol doses are characteristic of immature tissues exhibiting poorly developed calcium handling, suggesting maturation protocols may be required to obtain positive force-frequency relationships as observed in healthy adult human ventricular myocardium.

“The moderate positive chronotropy and reduction of stroke work observed at high isoproterenol doses are characteristic of immature tissues exhibiting poorly developed calcium handling properties8, suggesting that maturation protocols14,21,22,73 may be required to obtain positive force-frequency relationships, as observed in healthy adult human ventricular myocardium74.”

• cites [8] Karakikes, I., Ameen, M., Termglinchan, V. & Wu, J. C. Human induced pluripotent stem cell-derived cardiomyocytes: insights into molecular, cellular, and functional phenotypes. Circ. Res. 117, 80–88 (2015). sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [14] Nunes, S. S. et al. Biowire: a platform for maturation of human pluripotent stem cell-derived cardiomyocytes. Nat. Methods 10, 781–787 (2013). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [74] Endoh, M. Force–frequency relationship in intact mammalian ventricular myocardium: physiological and pathophysiological relevance. Eur. J. Pharmacol. 500, 73–86 (2004). sourceNot checked — no full text of the source

May combine two claims.

Contractile work in our ventricle models was measured using conductance catheters and was smaller than reported for cardiac organoid chambers based on NRVM or pluripotent hES2 human embryonic stem cell-derived cardiomyocytes, where volume changes were indirectly assessed from video recordings.

“Contractile work in our ventricle models was measured using conductance catheters and was smaller than reported for cardiac organoid chambers based on NRVM26 or pluripotent hES2 human embryonic stem cell-derived cardiomyocytes29, where volume changes were indirectly assessed from video recordings.”

• cites [26] Lee, E. J., Kim do, E., Azeloglu, E. U. & Costa, K. D. Engineered cardiac organoid chambers: toward a functional biological model ventricle. Tissue Eng. Part A 14, 215–225 (2008). sourceNot checked — no full text of the source
• cites [29] Li, R. A. et al. Bioengineering an electro-mechanically functional miniature ventricular heart chamber from human pluripotent stem cells. Biomaterials 163, 116–127 (2018). sourceSupported

May combine two claims.

The tensile elastic modulus of our scaffold in the direction of fiber alignment (EL ~500 kPa) was higher than healthy ventricular ECM (E ~350 kPa) and may have limited cardiomyocyte shortening during contraction.

“For example, the tensile elastic modulus of our scaffold in the direction of fiber alignment (EL ~ 500 kPa) was higher than healthy ventricular ECM (E ~350 kPa)68 and may have limited cardiomyocyte shortening during contraction.”

• cites [68] Quinn, K. P. et al. Optical metrics of the extracellular matrix predict compositional and mechanical changes after myocardial infarction. Sci. Rep. 6, 35823 (2016). sourcePartly supported

  The Results report tensile testing of healthy ventricular ECM and its elastic modulus, supporting the use of this paper as a comparator. But the available text does not give the cited value of approximately 350 kPa (searched: “350” and “kPa”). The scaffold modulus and possible effect on cardiomyocyte shortening are the citing authors’ own comparison and inference, not findings attributed to this source. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

May combine two claims.

The engineered ventricles seeded with NRVM or hiPSC-CM have a diastolic chamber volume of about 500 μL, similar to native rat ventricle and about 1/250 of human ventricle.

“Incorporating neonatal rat ventricular myocytes or cardiomyocytes derived from human induced pluripotent stem cells, the tissue-engineered ventricles have a diastolic chamber volume of ~500 μL (comparable to that of the native rat ventricle and approximately 1/250 the size of the human ventricle)”

May combine two claims.

Engineered scale-model ventricles of the human left heart, built from nanofibrous scaffolds, support anisotropic myocardial tissue formation and chamber-level contraction.

“Here, we report tissue-engineered scale models of the human left ventricle, made of nanofibrous scaffolds that promote native-like anisotropic myocardial tissue genesis and chamber-level contractile function.”

May combine two claims.

In all cases, spontaneous calcium activity showed stable excitation patterns with plane waves (healthy) or pinned spiral waves (injured) repeating at a near-constant rate between 4 Hz and 5 Hz for the duration of experiments (~2 hours).

“In all cases, spontaneous calcium activity showed stable excitation patterns with plane waves (healthy) or pinned spiral waves (injured) repeating at a near-constant rate (between 4 Hz and 5Hz) for the duration of experiments (~2 hours).”

May combine two claims.

Pressure/volume loops measured before and after isoproterenol exposure showed an isoproterenol-induced reduction in stroke work, concomitant with an increase in beat frequency.

“Pressure/volume loops measured before and after isoproterenol exposure showed an isoproterenol-induced reduction in stroke work, concomitant with an increase in beat frequency (Fig. 3b,c).”

May combine two claims.

Plane wave propagation was observed prior to injury, whereas injured ventricles generated spiral waves that were pinned to controlled anatomical defects.

“Plane wave propagation was observed prior to injury (Fig. 5a, top), whereas injured ventricles generated spiral waves that were pinned to the controlled anatomical defects (Fig. 5a, bottom panels, and Supplementary Movie 12).”

May combine two claims.

The self-contained instrumented heart bioreactor includes intra- and extra-ventricular flow loops, separate chambers for optional valve inserts, and additional access ports for catheters.

“The HBR includes both intra- and extra- ventricular flow loops, separate chambers for optional valve inserts, and additional access ports for catheters (Fig. 4a, Supplementary Fig. S8).”

May combine two claims.

Mean calcium wavefront propagation velocity from apex to base was 9.33 cm/sec for NRVM and 5.2 cm/sec for hiPSC-CM ventricles.

“Mean calcium wavefront propagation velocity from apex to base was 9.33 cm/sec or 5.2 cm/sec for NRVM or hiPSC-CM ventricles, respectively.”

May combine two claims.

The engineered ventricle chambers were sutured to tubing or bioreactor components, and stable contraction of NRVM and hiPSC-CM ventricles permitted time-dependent pressure and volume measurements.

“The resulting tissue-engineered ventricle chambers were sutured to tubing or bioreactor components through which catheter sensors were introduced and stable contraction of both NRVM and hiPSC-CM ventricles permitted time-dependent pressure and volume measurements.”

May combine two claims.

In our scaffold, gelatin enhanced cell and biomolecule adhesion during cell seeding, and PCL provided structural features (microporosity, nanotopography, anisotropy) that resisted degradation during culture.

“In our scaffold, gelatin was used to enhance cell and biomolecule adhesion during cell seeding, and the polymer backbone (PCL) provided structural features (microporosity, nanotopography, anisotropy) that resisted degradation during culture.”

May combine two claims.

Calcium fluorescence intensity measured near the rotor poles of a single-hole injury model showed consistent phase difference and a rotation rate of ~5 Hz.

“Calcium fluorescence intensity measured near the rotor poles of a single-hole injury model showed consistent phase difference and a rotation rate of ~ 5 Hz (Fig. 5b, Supplementary Figure S12, and Supplementary Movie 13).”

May combine two claims.

Using small animal echocardiography equipment, both unassisted natural spontaneous ventricle contraction and HBR-assisted contraction were recorded.

“Using small animal echocardiography equipment, we recorded both unassisted natural spontaneous ventricle contraction (Fig. 4c, left, and Supplementary Movie 10) and HBR-assisted contraction (Fig. 4c, right, and Supplementary Movie 11).”

May combine two claims.

Measured differences in chamber pressure were ~50 μmHg for rat or human ventricles, and volume change was ~5 μL (rat) or 1 μL (human).

“Measured differences in chamber pressure were ~50 μmHg (rat or human) and the volume change was ~5 μL (rat) or 1 μL (human).”

May combine two claims.

Synchronous, coordinated ventricle contraction developed spontaneously after 3-5 days of culture and persisted for duration of experimental procedures conducted 14 days after seeding.

“Synchronous, coordinated ventricle contraction developed spontaneously after 3–5 days of culture (Supplementary Movies 3,4) and persisted for the duration of experimental procedures (Supplementary Movie 5), conducted 14 days after seeding.”

May combine two claims.

Cyclic pressure applied to the extra-ventricular loop drives intra-ventricular fluid flow via assisted ventricle contraction, and unidirectional flow can be achieved using commercially available valves or custom valve inserts.

“Cyclic pressure applied to the extra-ventricular loop drives intra-ventricular fluid flow via assisted ventricle contraction, and unidirectional flow can be achieved using commercially available valves or with custom valve inserts in the HBR.”

May combine two claims.

Ventricle beat rates showed a positive chronotropic response over the concentration range in both NRVM and hiPSC-CM ventricles, as expected for healthy NRVM, hiPSC-CM, engineered hiPSC-CM cardiac tissues, and human patients.

“Ventricle beat rates showed a positive chronotropic response over the concentration range in both the NRVM and hiPSC-CM ventricles (Fig. 3c), as expected for healthy NRVM59, hiPSC-CM60, engineered hiPSC-CM cardiac tissues16, and human patients61.”

• cites [59] Simpson, P. & Savion, S. Differentiation of rat myocytes in single cell cultures with and without proliferating nonmyocardial cells. Cross-striations, ultrastructure, and chronotropic response to isoproterenol. Circ. Res. 50, 101–116 (1982). sourceNot checked — no full text of the source
• cites [60] Moretti, A. et al. Patient-specific induced pluripotent stem-cell models for long-QT syndrome. N. Engl. J. Med. 363, 1397–1409 (2010). sourceNot checked — no full text of the source
• cites [61] Koglin, J., Bohm, M., Vonscheidt, W., Stablein, A. & Erdmann, E. Antiadrenergic effect of carbachol but not of adenosine on contractility in the intact human ventricle in-vivo. J. Am. Coll. Cardiol. 23, 678–683 (1994). sourceNot checked — no full text of the source

May combine two claims.

Spontaneous beat rate of NRVM ventricles (~130 ±15 bpm) was higher than hiPSC-CM ventricles (~85 ± 15 bpm), and both increased by ~40% following exposure to 10−4 M isoproterenol.

“The spontaneous beat rate of NRVM ventricles (~130 ±15 bpm) was higher than hiPSC-CM ventricles (~85 ± 15 bpm), and both increased by ~40% following exposure to 10−4 M isoproterenol.”

May combine two claims.

These scaffold features provided sufficient structural integrity for ventricle culture and guided cardiomyocyte assembly.

“These features provided sufficient structural integrity for ventricle culture and they guided cardiomyocyte assembly”

May combine two claims.

Ejection fractions were ~1% (rat) or ~0.2% (human) and stroke work was ~0.25 mmHg × μL (rat) or ~0.05 mmHg × μL (human).

“Thus, ejection fractions were ~1% (rat) or ~0.2% (human) and stroke work was WS ~ 0.25 mmHg × μL (rat) or WS ~ 0.05 mmHg × μL (human).”

May combine two claims.

Regular beat frequencies were observed in calcium-containing M199 or Tyrode's solution, whereas exposure to calcium-free PBS led to broad beat rate distributions.

“Whereas regular beat frequencies were observed in calcium-containing M199 or Tyrode’s solution, exposure to calcium-free PBS led to broad beat rate distributions (Supplementary Fig. S7B).”

May combine two claims.

A non-proliferative hiPSC-CM line (Cor.4U) cultured in model ventricle scaffolds for 6 months preserved tissue anisotropy and stable pressure-volume loops could be recorded.

“We also cultured a non-proliferative hiPSC-CM line (Cor.4U) in model ventricle scaffolds for 6 months, demonstrating that tissue anisotropy was preserved (Supplementary Figure S14A) and stable pressure-volume loops could be recorded (Supplementary Figure S14 B).”

May combine two claims.

When cultured in differentiation media, resulting hiPSC-CM showed spontaneous contraction and early stages of sarcomeric assembly within 8-12 days, and anisotropic sarcomeric assembly with early z-disk alignment after 1 month.

“When cultured in differentiation media, the resulting hiPSC-CM showed spontaneous contraction and early stages of sarcomeric assembly within 8–12 days of culture (Supplementary Figure S13A, Day 12), and anisotropic sarcomeric assembly with early stages of z-disk alignment after 1 month in culture (Supplementary Figure S13A, Day 30).”

May combine two claims.

Both types of model cardiac chambers generated similarly shaped elliptical PV-loops, which are expected from ventricles contracting in the absence of valves and show similarities to PV loops obtained from patients with severe valvular insufficiencies.

“Both types of model cardiac chambers generated similarly shaped elliptical PV-loops (Fig. 3b, Supplementary Fig. S14), which are expected from ventricles contracting in the absence of valves and show similarities to PV loops obtained from patients with severe valvular insufficiencies78.”

• cites [78] Klabunde, R. E. Cardiovascular Physiology Concepts 2nd edn (Lippincott Williams & Wilkins/Wolters Kluwer, Philadelphia, 2012).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The EF of our tissue-engineered rat ventricles was ~1% (1/50 EF of healthy rats), suggesting that discontinuities in cardiomyocyte coverage limited tissue-engineered ventricle contractile strength.

“The EF of our tissue-engineered rat ventricles was ~1% (1/50 EF of healthy rats), suggesting that discontinuities in cardiomyocyte coverage limited tissue-engineered ventricle contractile strength.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The conductance/volume catheter response was non-linear, as expected for these systems.

“We observed a non-linear conductance/volume catheter response (Supplementary Fig. 4B.i), as expected for these systems82.”

• cites [82] Pearce, J. A., Porterfield, J. E., Larson, E. R., Valvano, J. W. & Feldman, M. D. Accuracy considerations in catheter based estimation of left ventricular volume. Conf. Proc. IEEE Eng. Med. Biol. Soc. 2010, 3556–3558 (2010). sourceNot checked — no full text of the source

May combine two claims.

Both uninjured ventricles showed evidence of spontaneously generated calcium plane wave propagation, but one had greater homogeneity.

“Both showed evidence of spontaneously generated calcium plane wave propagation but one had greater homogeneity; this favorable sample is reported in our revised manuscript.”

May combine two claims.

Cell density in our ventricles, estimated by counting immunostained NRVM ventricle surfaces and cross-sections, was ~90,000 cells/mm3 for a total cell number ~2.3 × 10^6 in a 26 mm3 scaffold volume, approximately 10-fold less than in 21-day-old or 3-month-old rat hearts.

“The cell density in our ventricles, estimated by counting immunostained (DAPI) NRVM ventricle surfaces and cross-sections (Supplementary Fig. S3), was ~90,000 cells/mm3 for a total cell number ~2.3 × 106 in a 26 mm3 scaffold volume, which is approximately 10-fold less than in 21-day-old or 3-month-old rat hearts75.”

• cites [75] Bai, S. L., Campbell, S. E., Moore, J. A., Morales, M. C. & Gerdes, A. M. Influence of age, growth, and sex on cardiac myocyte size and number in rats. Anat. Rec. 226, 207–212 (1990). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S4 (based).

Direct comparison with natural ventricle pressure and volume dynamics requires three-dimensional contractile cardiac chambers.

“but direct comparison with natural ventricle pressure and volume dynamics requires three-dimensional (3D) contractile cardiac chambers.”

Classified as probably not a substantial claim. May combine two claims.

hiPSC-CM are assembled into functional engineered heart tissues, including muscular thin films or 3D muscle strips, to model contractile pathophysiologies, promote maturation, and produce drug responses increasingly comparable to human patients.

“These cells are assembled into functional engineered heart tissues2,9,10, including muscular thin films11,12 or 3D muscle strips13–20, to model contractile pathophysiologies11, promote hiPSC-CM maturation9,14,15,21, and produce drug responses that are increasingly comparable to human patients16,18,22.”

• cites [2] Tzatzalos, E., Abilez, O. J., Shukla, P. & Wu, J. C. Engineered heart tissues and induced pluripotent stem cells: macro- and microstructures for disease modeling, drug screening, and translational studies. Adv. Drug Deliv. Rev. 96, 234–244 (2016). sourceNot checked — no full text of the source
• cites [9] Feric, N. T. & Radisic, M. Maturing human pluripotent stem cell-derived cardiomyocytes in human engineered cardiac tissues. Adv. Drug Deliv. Rev. 96, 110–134 (2016). sourceNot checked — no full text of the source
• cites [10] Eder, A., Vollert, I., Hansen, A. & Eschenhagen, T. Human engineered heart tissue as a model system for drug testing. Adv. Drug Deliv. Rev. 96, 214–224 (2016). sourceNot checked — no full text of the source

Classified as probably not a substantial claim. May combine two claims.

High maintenance costs and low experimental throughput of animal models motivate development of alternative in vitro cardiology assays based on human cells.

“These and other limitations associated with animal models, for example high maintenance costs and low experimental throughput, motivate the development of alternative in vitro cardiology assays based on human cells.”

May combine two claims.

These scaffold properties allowed fabrication of ventricle scaffolds that were structurally stable and permissive to chamber contraction by cardiomyocyte shortening.

“These properties allowed us to fabricate ventricle scaffolds that were both structurally stable and permissive to chamber contraction by cardiomyocyte shortening.”

May combine two claims.

Echocardiography performed in the absence of extra-ventricular tissues can improve image clarity compared with in vivo studies, underscoring the advantage of organ modularity in the HBR.

“Echocardiography performed in the absence of extra-ventricular tissues can improve image clarity compared with in vivo studies, underscoring the advantage of organ modularity in our HBR.”

May combine two claims.

In this configuration, cultured ventricles can be exposed to externally-controlled physiological or pathological pressure variations and PV loops acquired with or without valves.

“In this configuration, cultured ventricles can be exposed to externally-controlled physiological or pathological pressure variations and PV loops acquired with or without valves (Fig. 4b)”

Probably not a substantial claim: may not pass S3 (load-bearing).

Anisotropic PCL/gelatin nanofiber production by pull spinning and their use to guide skeletal muscle tissue assembly were previously described.

“We previously described anisotropic PCL/gelatin nanofiber production by pull spinning and their use to guide skeletal muscle tissue assembly46.”

• cites [46] Deravi, L. F. et al. Design and fabrication of fibrous nanomaterials using pull spinning. Macromol. Mater. Eng. 302, 1600404 (2017). sourceNot checked — no full text of the source

May combine two claims.

The myocardium is a composite in which the dominant stiffness shifts from myocytes to the ECM with increasing strain, emphasizing the ECM's role maintaining structural integrity.

“Scaffold engineering should account for the fact that the myocardium is a composite in which the dominant stiffness shifts from myocytes to the ECM with increasing strain67, emphasizing the ECM’s role maintaining structural integrity.”

• cites [67] Chaturvedi, R. R. et al. Passive stiffness of myocardium from congenital heart disease and implications for diastole. Circulation 121, 979–988 (2010). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S2 (checkable).

Results have implications for preclinical cardiology and regenerative medicine research where human organ models are sought to improve translation of therapeutic strategies.

“These results have implications for preclinical cardiology and regenerative medicine research where human organ models are sought to improve translation of therapeutic strategies.”

May combine two claims.

Response to adrenergic agonists is a fundamental aspect of myocardial function, studied extensively in rodents and humans, making β-adrenergic response a good test of engineered ventricles' ability to recapitulate normal cardiac pharmacology.

“A fundamental aspect of myocardial function is the response to adrenergic agonists, which has been studied extensively in both rodents and humans, making β-adrenergic response a good test of the ability of our engineered ventricles to recapitulate normal cardiac pharmacology57,58.”

• cites [57] Barrett, A. M. & Carter, J. Comparative chronotropic activity of beta-adrenoceptive antagonists. Br. J. Pharmacol. 40, 373–381 (1970). sourceNot checked — no full text of the source
• cites [58] Brito-Martins, M., Harding, S. E. & Ali, N. N. Beta(1)- and beta(2)-adrenoceptor responses in cardiomyocytes derived from human embryonic stem cells: comparison with failing and non-failing adult human heart. Br. J. Pharmacol. 153, 751–759 (2008). sourceNot checked — no full text of the source

May combine two claims.

Gelatin is an RGD-containing biopolymer derived from denatured collagen that improves scaffold binding to cells and biomolecules such as fibronectin.

“while gelatin was chosen as an RGD-containing biopolymer derived from denatured collagen that improves scaffold binding to cells and biomolecules such as fibronectin47,48.”

• cites [47] Ruoslahti, E. RGD and other recognition sequences for integrins. Annu Rev. Cell Dev. Biol. 12, 697–715 (1996). sourceNot checked — no full text of the source
• cites [48] Katagiri, Y., Brew, S. A. & Ingham, K. C. All six modules of the gelatin-binding domain of fibronectin are required for full affinity. J. Biol. Chem. 278, 11897–11902 (2003). sourceNot checked — no full text of the source

May combine two claims.

These preliminary results suggest that scaffolds support functional myocardial tissue production using relatively small numbers of seeded hiPSC that can subsequently be cultured for extended time periods.

“These preliminary results suggest that our scaffolds support functional myocardial tissue production using relatively small numbers of seeded hiPSC that can subsequently be cultured for extended time periods.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Use of conductance catheters was advantageous for direct volume readouts, but electrical pacing during catheterization was not recommended by the catheter manufacturer and therefore not performed.

“Our use of conductance catheters was advantageous for direct volume readouts but electrical pacing during catheterization was not recommended by the catheter manufacturer and therefore not performed in these studies.”

Probably not a substantial claim: may not pass S3 (load-bearing).

All animal procedures were approved by the Harvard Animal Care and Use Committee.

“All procedures were approved by the Harvard Animal Care and Use Committee”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

Including a nanofibrous component to printable inks would be advantageous for directing cardiomyocyte shape and assembly in printed scaffolds or tissues.

“Our work suggests that including a nanofibrous component to printable inks would be advantageous for directing cardiomyocyte shape and assembly in printed scaffolds or tissues.”