Cited by 423D Printing in Biomedical ResearchTissue Engineering and Regenerative MedicinePluripotent Stem Cells Research

Functional microvascularization of human myocardium in vitro

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King, Oisín, Cruz-Moreira, Daniela, Sayed, Alaa, Kermani, Fatemeh, Kit-Anan, Worrapong, Sunyovszki, Ilona, Wang, Brian X., Downing, Barrett +6 more·2022·Cell Reports Methods

Abstract

In this study, we report static and perfused models of human myocardial-microvascular interaction. In static culture, we observe distinct regulation of electrophysiology of human induced pluripotent stem cell derived-cardiomyocytes (hiPSC-CMs) in co-culture with human cardiac microvascular endothelial cells (hCMVECs) and human left ventricular fibroblasts (hLVFBs), including modification of beating rate, action potential, calcium handling, and pro-arrhythmic substrate. Within a heart-on-a-chip model, we subject this three-dimensional (3D) co-culture to microfluidic perfusion and vasculogenic growth factors to induce spontaneous assembly of perfusable myocardial microvasculature. Live imaging of red blood cells within myocardial microvasculature reveals pulsatile flow generated by beating hiPSC-CMs. This study therefore demonstrates a functionally vascularized in vitro model of human myocardium with widespread potential applications in basic and translational research.

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  • hCMEC supports efficient metabolic and electrical function by increasing oxygenation and electrophysiological properties through the release of vascular endothelial growth factor (VEGF) and nitric oxide.

    “Moreover hCMEC supports efficient metabolic and electrical function by increasing oxygenation and electrophysiological properties through the release of vascular endothelial growth factor (VEGF) and nitric oxide.[ 55 , 56 ]”

    From Engineered in vitro multi-cell type ventricle model generates long-term pulsatile flow and modulates cardiac output in response to cardioactive drugs (2025) · cites this paper as [56]

    The Results section reports that human cardiac microvascular endothelial cell co-culture altered iPSC-cardiomyocyte electrophysiology, including membrane potentials and arrhythmia measures. It does not establish improved oxygenation or metabolic function, or show that VEGF and nitric oxide released by those cells caused the effects. In STAR★Methods, VEGF is described as a supplement added to the culture, not as a measured endothelial-cell release (page numbers unavailable). (LLM, conf=0.88)

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  1. Ashikawa K. Kanatsuka H. Suzuki T. Takishima T. Phasic blood flow velocity pattern in epimyocardial microvessels in the beating canine left ventricle Circ. Res. 59 1986 704 711 10.1161/01.RES.59.6.704 3815760 · DOI
  2. Baeyens N. Nicoli S. Coon B.G. Ross T.D. Van den Dries K. Han J. Lauridsen H.M. Mejean C.O. Eichmann A. Thomas J.L. Vascular remodeling is governed by a VEGFR3-dependent fluid shear stress set poin Elife 4 2015 1 35 10.7554/ELIFE.04645 PMC4337723 25643397 · DOI
  3. Beauchamp P. Jackson C.B. Ozhathil L.C. Agarkova I. Galindo C.L. Sawyer D.B. Suter T.M. Zuppinger C. 3D co-culture of hiPSC-derived cardiomyocytes with cardiac fibroblasts improves tissue-like features of cardiac spheroids Front. Mol. Biosci. 7 2020 14 10.3389/fmolb.2020.00014 32118040 PMC7033479 · DOI · Paper page
  4. Berry C. Duncker D.J. Coronary microvascular disease: the next frontier for cardiovascular research Cardiovasc. Res. 116 2020 737 740 https://pubmed.ncbi.nlm.nih.gov/32149331/ 32149331 PMC7061275
  5. Blache U. Ehrbar M. Inspired by nature: hydrogels as versatile tools for vascular engineering Adv. Wound Care 7 2018 232 246 10.1089/wound.2017.0760 PMC6032659 29984113 · DOI
  6. Brutsaert D.L. Cardiac endothelial-myocardial signaling: its role in cardiac growth, contractile performance, and rhythmicity Physiol. Rev. 83 2003 59 115 10.1152/physrev.00017.2002 12506127 · DOI · Paper page
  7. Chobanyan-Jürgens K. Heusser K. Duncker D. Veltmann C. May M. Mehling H. Luft F.C. Schröder C. Jordan J. Tank J. Cardiac pacemaker channel (HCN4) inhibition and atrial arrhythmogenesis after releasing cardiac sympathetic activation Sci. Rep. 8 2018 7748 10.1038/S41598-018-26099-9 29773827 PMC5958126 · DOI
  8. Ellis B.W. Acun A. Can U.I. Zorlutuna P. Human IPSC-derived myocardium-on-chip with capillary-like flow for personalized medicine Biomicrofluidics 11 2017 024105 10.1063/1.4978468 28396709 PMC5367145 · DOI
  9. Ewald M.L. Chen Y.H. Lee A.P. Hughes C.C.W. The vascular niche in next generation microphysiological systems Lab Chip 21 2021 3244 3262 10.1039/D1LC00530H 34396383 PMC8635227 · DOI
  10. Fang Y. Wu D. Birukov K.G. Mechanosensing and mechanoregulation of endothelial cell functions Comprehensive Physiology 2019 Wiley 873 904 10.1002/cphy.c180020 PMC6697421 30873580 · DOI
  11. Fleming I. Myoendothelial gap junctions Circ. Res. 86 2000 249 250 10.1161/01.RES.86.3.249 10679472 · DOI
  12. Garoffolo G. Pesce M. Mechanotransduction in the cardiovascular system: from developmental origins to homeostasis and pathology Cells 2019 10.3390/cells8121607 PMC6953076 31835742 · DOI
  13. Ghajar C.M. Chen X. Harris J.W. Suresh V. Hughes C.C.W. Jeon N.L. Putnam A.J. George S.C. The effect of matrix density on the regulation of 3-D capillary morphogenesis Biophys. J. 94 2008 1930 1941 10.1529/biophysj.107.120774 17993494 PMC2242748 · DOI
  14. Giacomelli E. Meraviglia V. Campostrini G. Cochrane A. Cao X. Van Helden R.W. Garcia A.K. Mircea M. Kostidis S. Davis R.P. Human-iPSC-derived cardiac stromal cells enhance maturation in 3D cardiac microtissues and reveal non-cardiomyocyte contributions to heart disease Cell Stem Cell 26 2020 862 879.e11 10.1016/j.stem.2020.05.004 32459996 PMC7284308 · DOI · Paper page
  15. Goldfracht I. Efraim Y. Shinnawi R. Kovalev E. Huber I. Gepstein A. Arbel G. Shaheen N. Tiburcy M. Zimmermann W.H. Engineered heart tissue models from hipsc-derived cardiomyocytes and cardiac ecm for disease modeling and drug testing applications Acta Biomaterialia 92 2019 145 159 10.1016/j.actbio.2019.05.016 31075518 · DOI · Paper page
  16. Ha H. Nam K.H. Lee S.J. Hybrid PIV–PTV technique for measuring blood flow in rat mesenteric vessels Microvasc. Res. 84 2012 242 248 10.1016/J.MVR.2012.07.004 22820216 · DOI
  17. Hellberg K. Wayland H. Rickart A.L. Bing R.J. Studies on the coronary microcirculation by direct visualization Am. J. Cardiol. 29 1972 593 597 10.1016/0002-9149(72)90158-0 5021488 · DOI
  18. Huang C.P. Lu J. Seon H. Lee A.P. Flanagan L.A. Kim H.Y. Putnam A.J. Jeon N.L. Engineering microscale cellular niches for three-dimensional multicellular co-cultures Lab Chip 9 2009 1740 1748 10.1039/b818401a 19495458 PMC3758562 · DOI · Paper page
  19. Huebsch N. Loskill P. Mandegar M.A. Marks N.C. Sheehan A.S. Ma Z. Mathur A. Nguyen T.N. Yoo J.C. Judge L.M. Automated video-based analysis of contractility and calcium flux in human-induced pluripotent stem cell-derived cardiomyocytes cultured over different spatial scales Tissue Eng. Part C Methods 215 2015 467 479 10.1089/ten.tec.2014.0283 PMC4410286 25333967 · DOI
  20. Imoto Y. Ehara T. Matsuura H. Voltage- and time-dependent block of Ik1 underlying Ba2+-induced ventricular automaticity Am. J. Physiol. 252 1987 H325 H333 10.1152/AJPHEART.1987.252.2.H325 2433951 · DOI
  21. Irisawa H. Brown H.F. Giles W. Cardiac pacemaking in the sinoatrial node Physiol. Rev. 73 1993 197 227 10.1152/physrev.1993.73.1.197 8380502 · DOI
  22. Jabbour R.J. Owen T.J. Pandey P. Reinsch M. Wang B. King O. Couch L.S. Pantou D. Pitcher D.S. Chowdhury R.A. In vivo grafting of large engineered heart tissue patches for cardiac repair JCI Insight 6 2021 144068 10.1172/JCI.INSIGHT.144068 34369384 PMC8410032 · DOI
  23. Jeon J.S. Bersini S. Whisler J.A. Chen M.B. Dubini G. Charest J.L. Moretti M. Kamm R.D. Generation of 3D functional microvascular networks with human mesenchymal stem cells in microfluidic systems Integr. Biol. 6 2014 555 563 10.1039/c3ib40267c PMC4307755 24676392 · DOI
  24. Jost N. Nagy N. Corici C. Kohajda Z. Horváth A. Acsai K. Biliczki P. Levijoki J. Pollesello P. Koskelainen T. ORM-10103, a novel specific inhibitor of the Na+/Ca2+ exchanger, decreases early and delayed afterdepolarizations in the canine heart Br. J. Pharmacol. 170 2013 768 10.1111/BPH.12228 23647096 PMC3799592 · DOI
  25. Kane C. Terracciano C.M. Human cardiac fibroblasts engage the Sarcoplasmic reticulum in induced pluripotent stem cell-derived cardiomyocyte excitation–contraction coupling J. Am. Coll. Cardiol. 72 2018 1061 1063 10.1016/j.jacc.2018.06.028 30139435 · DOI
  26. Kane C. Terracciano C.M.N. Concise review: criteria for chamber-specific categorization of human cardiac myocytes derived from pluripotent stem cells Stem Cells 35 2017 1881 1897 10.1002/stem.2649 28577296 PMC5575566 · DOI
  27. Karbassi E. Fenix A. Marchiano S. Muraoka N. Nakamura K. Yang X. Murry C.E. Cardiomyocyte maturation: advances in knowledge and implications for regenerative medicine Nat. Rev. Cardiol. 17 2020 341 359 10.1038/S41569-019-0331-X 32015528 PMC7239749 · DOI
  28. Kassab G.S. Fung Y.C. Topology and dimensions of pig coronary capillary network Am. J. Physiol. 267 1994 H319 H325 10.1152/ajpheart.1994.267.1.h319 8048597 · DOI
  29. Kim J.J. Yang L. Lin B. Zhu X. Sun B. Kaplan A.D. Bett G.C. Rasmusson R.L. London B. Salama G. Mechanism of automaticity in cardiomyocytes derived from human induced pluripotent stem cells J. Mol. Cell. Cardiol. 81 2015 81 93 10.1016/j.yjmcc.2015.01.013 25644533 PMC4409767 · DOI
  30. Kim S. Chung M. Ahn J. Lee S. Jeon N.L. Interstitial flow regulates the angiogenic response and phenotype of endothelial cells in a 3D culture model Lab Chip 16 2016 4189 4199 http://xlink.rsc.org/?DOI=C6LC00910G 27722679
  31. King O. Sunyovszki I. Terracciano C.M. Vascularisation of pluripotent stem cell–derived myocardium: biomechanical insights for physiological relevance in cardiac tissue engineering Pflugers Arch. 473 2021 1117 1136 10.1007/s00424-021-02557-8 33855631 PMC8245389 · DOI
  32. Kohl P. Kamkin A.G. Kiseleva I.S. Noble D. Mechanosensitive fibroblasts in the sino-atrial node region of rat heart: interaction with cardiomyocytes and possible role Exp. Physiol. 79 1994 943 956 10.1113/expphysiol.1994.sp003819 7873162 · DOI
  33. Lim S.L. Lam C.S. Segers V.F. Brutsaert D.L. De Keulenaer G.W. Cardiac endothelium–myocyte interaction: clinical opportunities for new heart failure therapies regardless of ejection fraction Eur. Heart J. 36 2015 2050 2060 10.1093/eurheartj/ehv132 25911648 · DOI
  34. Marcu R. Choi Y.J. Xue J. Fortin C.L. Wang Y. Nagao R.J. Xu J. MacDonald J.W. Bammler T.K. Murry C.E. Human organ-specific endothelial cell heterogeneity iScience 4 2018 20 35 30240741 PMC6147238
  35. Mason B.N. Starchenko A. Williams R.M. Bonassar L.J. Reinhart-King C.A. Tuning three-dimensional collagen matrix stiffness independently of collagen concentration modulates endothelial cell behavior Acta Biomater. 9 2013 4635 4644 10.1016/j.actbio.2012.08.007 22902816 PMC3508162 · DOI
  36. Mayourian J. Ceholski D.K. Gonzalez D.M. Cashman T.J. Sahoo S. Hajjar R.J. Costa K.D. Physiologic, pathologic, and therapeutic paracrine modulation of cardiac excitation-contraction coupling Circ. Res. 122 2018 167 183 10.1161/CIRCRESAHA.117.311589 29301848 PMC5886757 · DOI
  37. McCormick M.E. Tzima E. Pulling on my heartstrings: mechanotransduction in cardiac development and function Curr. Opin. Hematol. 23 2016 235 242 10.1097/MOH.0000000000000240 26906028 PMC4823169 · DOI
  38. Morin K.T. Tranquillo R.T. In vitro models of angiogenesis and vasculogenesis in fibrin gel Exp. Cell Res. 2013 2409 2417 10.1016/j.yexcr.2013.06.006 23800466 PMC3919069 · DOI
  39. Nagaraju C.K. Dries E. Gilbert G. Abdesselem M. Wang N. Amoni M. Driesen R.B. Sipido K.R. Myofibroblast modulation of cardiac myocyte structure and function Sci. Rep. 9 2019 8879 10.1038/S41598-019-45078-2 31222006 PMC6586929 · DOI
  40. Newman A.C. Nakatsu M.N. Chou W. Gershon P.D. Hughes C.C.W. The requirement for fibroblasts in angiogenesis: fibroblast-derived matrix proteins are essential for endothelial cell lumen formation Mol. Biol. Cell 22 2011 3791 3800 10.1091/mbc.E11-05-0393 21865599 PMC3192859 · DOI
  41. Nippert F. Schreckenberg R. Schlüter K.D. Isolation and cultivation of adult rat cardiomyocytes J. Vis. Exp. 2017 2017 10.3791/56634 PMC5752423 29155786 · DOI
  42. Noor N. Shapira A. Edri R. Gal I. Wertheim L. Dvir T. 3D printing of personalized thick and perfusable cardiac patches and hearts Adv. Sci. 6 2019 1900344 10.1002/advs.201900344 PMC6548966 31179230 · DOI · Paper page
  43. Ongstad E. Kohl P. Fibroblast-myocyte coupling in the heart: potential relevance for therapeutic interventions J. Mol. Cel. Cardiol. 2016 238 246 10.1016/j.yjmcc.2016.01.010 PMC5022561 26774702 · DOI
  44. Perbellini F. Watson S.A. Bardi I. Terracciano C.M. Heterocellularity and cellular cross-talk in the cardiovascular system Front. Cardiovascular Med. 2018 143 10.3389/fcvm.2018.00143 PMC6221907 30443550 · DOI
  45. Pollet A.M.A.O. den Toonder J.M.J. Recapitulating the vasculature using Organ-on-Chip technology Bioengineering 7 2020 E17 10.3390/bioengineering7010017 32085464 PMC7175276 · DOI · Paper page
  46. Ravenscroft S.M. Pointon A. Williams A.W. Cross M.J. Sidaway J.E. Cardiac non-myocyte cells show enhanced pharmacological function suggestive of contractile Maturity in stem cell derived cardiomyocyte microtissues Toxicol. Sci. 152 2016 99 10.1093/TOXSCI/KFW069 27125969 PMC4922542 · DOI
  47. Rodrigues I.C. Kaasi A. Maciel Filho R. Jardini A.L. Gabriel L.P. Cardiac tissue engineering: current state-of-the-art materials, cells and tissue formation Einstein 2018 eRB4538 10.1590/S1679-45082018RB4538 30281764 PMC6178861 · DOI
  48. Rook M.B. Jongsma H.J. de Jonge B. Single channel currents of homo- and heterologous gap junctions between cardiac fibroblasts and myocytes Pflugers Arch. 414 1989 95 98 10.1007/BF00585633 2471143 · DOI
  49. Sakaguchi K. Shimizu T. Horaguchi S. Sekine H. Yamato M. Umezu M. Okano T. In vitro engineering of vascularized tissue surrogates Sci. Rep. 3 2013 1316 1317 10.1038/srep01316 23419835 PMC3575583 · DOI
  50. Sala L. van Meer B.J. Tertoolen L.G.J. Bakkers J. Bellin M. Davis R.P. Denning C. Dieben M.A.E. Eschenhagen T. Giacomelli E. MUSCLEMOTIONNovelty and significance Circ. Res. 122 2018 e5 e16 10.1161/CIRCRESAHA.117.312067 29282212 PMC5805275 · DOI · Paper page
  51. Saucerman J.J. Tan P.M. Buchholz K.S. McCulloch A.D. Omens J.H. Mechanical Regulation of Gene Expression in Cardiac Myocytes and Fibroblasts Nat. Rev. Cardiol. 2019 361 378 10.1038/s41569-019-0155-8 30683889 PMC6525041 · DOI
  52. Shin Y. Jeon J.S. Han S. Jung G.S. Shin S. Lee S.H. Sudo R. Kamm R.D. Chung S. In vitro 3D collective sprouting angiogenesis under orchestrated ANG-1 and VEGF gradients Lab Chip 11 2011 2175 2181 10.1039/c1lc20039a 21617793 · DOI
  53. Skylar-Scott M.A. Tan P.M. Buchholz K.S. McCulloch A.D. Omens J.H. Biomanufacturing of organ-specific tissues with high cellular density and embedded vascular channels Sci. Adv. 5 2019 eaaw2459 10.1126/sciadv.aaw2459 31523707 PMC6731072 · DOI
  54. Sorop O. Van De Wouw J. Chandler S. Ohanyan V. Tune J.D. Chilian W.M. Merkus D. Bender S.B. Duncker D.J. Experimental animal models of coronary microvascular dysfunction Cardiovasc. Res. 2020 756 770 10.1093/cvr/cvaa002 31926020 PMC7061277 · DOI
  55. Tinevez J.Y. Perry N. Schindelin J. Hoopes G.M. Reynolds G.D. Laplantine E. Bednarek S.Y. Shorte S.L. Eliceiri K.W. TrackMate: An Open and Extensible Platform for Single-Particle Tracking Methods 115 2017 80 90 10.1016/j.ymeth.2016.09.016 27713081 · DOI
  56. Tirziu D. Simons M. Endothelium as master regulator of organ development and growth Vascul. Pharmacol. 50 2009 1 7 10.1016/j.vph.2008.08.003 18804188 PMC2630387 · DOI
  57. Ugolini G.S. Visone R. Cruz-Moreira D. Mainardi A. Rasponi M. Generation of functional cardiac microtissues in a beating heart-on-a-chip Methods in Cell Biology 2018 Academic Press Inc. 69 84 10.1016/bs.mcb.2018.05.005 30037467 · DOI
  58. Vasquez C. Benamer N. Morley G.E. The cardiac fibroblast: functional and electrophysiological considerations in healthy and diseased hearts J. Cardiovasc. Pharmacol. 57 2011 380 388 10.1097/FJC.0B013E31820CDA19 21242811 PMC3077441 · DOI
  59. Wagner J.U.G. Pham Minh Duc Nicin Luka Hammer Marie Bottermann Katharina Yuan Ting Sharma Rahul John David Muhly-Reinholz Marion Tombor Lukas Dissection of heterocellular cross-talk in vascularized cardiac tissue mimetics J. Mol. Cell. Cardiol. 138 2020 269 282 10.1016/j.yjmcc.2019.12.005 31866374 · DOI
  60. Xiao Y. Zhang B. Liu H. Miklas J.W. Gagliardi M. Pahnke A. Thavandiran N. Sun Y. Simmons C. Keller G. Radisic M. Microfabricated perfusable cardiac biowire: a platform that mimics native cardiac bundle Lab Chip 14 2014 869 882 10.1039/c3lc51123e 24352498 PMC3969269 · DOI
  61. Yaniv Y. Lakatta E.G. Maltsev V.A. From two competing oscillators to one coupled-clock pacemaker cell system Front. Physiol. 2015 28 10.3389/fphys.2015.00028 25741284 PMC4327306 · DOI
  62. Zhang B. Montgomery M. Chamberlain M.D. Ogawa S. Korolj A. Pahnke A. Wells L.A. Massé S. Kim J. Reis L. Biodegradable scaffold with built-in vasculature for organ-on-a-chip engineering and direct surgical anastomosis Nat. Mater. 15 2016 669 678 10.1038/nmat4570 26950595 PMC4879054 · DOI · Paper page

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Authors
King, O., Cruz-Moreira, D., Sayed, A., Kermani, F., Kit-Anan, W., Sunyovszki, I., Wang, B. X., Downing, B., Fourre, J., Hachim, D., Randi, A. M., Stevens, M. M., Rasponi, M., & Terracciano, C. M.
Affiliations
  • Imperial College London (GB)
  • Politecnico di Milano (IT)
Corresponding author
  • King, Oisín
  • Terracciano, Cesare M.
Venue
Cell Reports Methods
Publisher
Elsevier BV
Published
2022-09
Volume
2
Issue
9
Pages
100280
ISSN
2667-2375 (ISSN-L)
OpenAlex
W4293462382
Cited by
42
References
8
Citations by year
2026: 9 · 2025: 11 · 2024: 10 · 2023: 12
FWCI
2.40
Type
journal article
Language
en
Open access
Locations
  • Cell Reports Methods (publishedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • Virtual Community of Pathological Anatomy (University of Castilla La Mancha) (submittedVersion, cc-by-nc-nd)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Spiral (Imperial College London) (submittedVersion, other-oa)
Funders
  • British Heart Foundation (FS/16/56/32732, NP001-06-2015, MED_CT_17_079)
  • Universität Heidelberg
  • Gladstone Institutes
Topics
  • Physical Sciences › Engineering › Biomedical Engineering › 3D Printing in Biomedical Research
  • Health Sciences › Medicine › Surgery › Tissue Engineering and Regenerative Medicine
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Pluripotent Stem Cells Research
Keywords
human induced pluripotent stem cell-derived cardiomyocytes, cardiac microvascular endothelial cells, co-culture, heart-on-a-chip, microfluidic perfusion, beating frequency, action potential, calcium handling, pulsatile flow, red blood cell imaging, 3D co-culture
MeSH terms
Humans, Myocardium, Coculture Techniques, Myocytes, Cardiac, Endothelial Cells, Induced Pluripotent Stem Cells

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