Review Article | Published:

The epicardium as a hub for heart regeneration

Nature Reviews Cardiology (2018) | Download Citation

Abstract

After decades of directed research, no effective regenerative therapy is currently available to repair the injured human heart. The epicardium, a layer of mesothelial tissue that envelops the heart in all vertebrates, has emerged as a new player in cardiac repair and regeneration. The epicardium is essential for muscle regeneration in the zebrafish model of innate heart regeneration, and the epicardium also participates in fibrotic responses in mammalian hearts. This structure serves as a source of crucial cells, such as vascular smooth muscle cells, pericytes, and fibroblasts, during heart development and repair. The epicardium also secretes factors that are essential for proliferation and survival of cardiomyocytes. In this Review, we describe recent advances in our understanding of the biology of the epicardium and the effect of these findings on the candidacy of this structure as a therapeutic target for heart repair and regeneration.

Key points

  • The epicardium is a layer of mesothelial tissue that envelops the heart in all vertebrates.

  • The epicardium contributes essential cells and signals during heart development and regeneration.

  • The epicardium comprises a heterogeneous cell population and is a highly regenerative tissue.

  • The epicardium is required for normal myocardial regeneration in zebrafish.

  • Current research approaches aim to activate the adult epicardium to promote heart regeneration.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from $8.99

All prices are NET prices.

Additional information

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

References

  1. 1.

    Tzahor, E. & Poss, K. D. Cardiac regeneration strategies: staying young at heart. Science 356, 1035–1039 (2017).

  2. 2.

    Cahill, T. J., Choudhury, R. P. & Riley, P. R. Heart regeneration and repair after myocardial infarction: translational opportunities for novel therapeutics. Nat. Rev. Drug Discov. 16, 699–717 (2017).

  3. 3.

    Galdos, F. X. et al. Cardiac regeneration: lessons from development. Circ. Res. 120, 941–959 (2017).

  4. 4.

    Uygur, A. & Lee, R. T. Mechanisms of cardiac regeneration. Dev. Cell 36, 362–374 (2016).

  5. 5.

    Zhang, Y., Mignone, J. & MacLellan, W. R. Cardiac regeneration and stem cells. Physiol. Rev. 95, 1189–1204 (2015).

  6. 6.

    Huang, G. N. et al. C/EBP transcription factors mediate epicardial activation during heart development and injury. Science 338, 1599–1603 (2012).

  7. 7.

    Kikuchi, K. et al. tcf21+ epicardial cells adopt non-myocardial fates during zebrafish heart development and regeneration. Development 138, 2895–2902 (2011).

  8. 8.

    Smart, N. et al. De novo cardiomyocytes from within the activated adult heart after injury. Nature 474, 640–644 (2011).

  9. 9.

    Zhou, B. et al. Adult mouse epicardium modulates myocardial injury by secreting paracrine factors. J. Clin. Invest. 121, 1894–1904 (2011).

  10. 10.

    Wang, J., Karra, R., Dickson, A. L. & Poss, K. D. Fibronectin is deposited by injury-activated epicardial cells and is necessary for zebrafish heart regeneration. Dev. Biol. 382, 427–435 (2013).

  11. 11.

    Smart, N. et al. Thymosin beta4 induces adult epicardial progenitor mobilization and neovascularization. Nature 445, 177–182 (2007).

  12. 12.

    Lepilina, A. et al. A dynamic epicardial injury response supports progenitor cell activity during zebrafish heart regeneration. Cell 127, 607–619 (2006).

  13. 13.

    Poss, K. D., Wilson, L. G. & Keating, M. T. Heart regeneration in zebrafish. Science 298, 2188–2190 (2002).

  14. 14.

    Marin-Juez, R. et al. Fast revascularization of the injured area is essential to support zebrafish heart regeneration. Proc. Natl Acad. Sci. USA 113, 11237–11242 (2016).

  15. 15.

    Lai, S. L. et al. Reciprocal analyses in zebrafish and medaka reveal that harnessing the immune response promotes cardiac regeneration. eLife 6, e25605 (2017).

  16. 16.

    Gonzalez-Rosa, J. M., Martin, V., Peralta, M., Torres, M. & Mercader, N. Extensive scar formation and regression during heart regeneration after cryoinjury in zebrafish. Development 138, 1663–1674 (2011).

  17. 17.

    Kikuchi, K. et al. Primary contribution to zebrafish heart regeneration by gata4+ cardiomyocytes. Nature 464, 601–605 (2010).

  18. 18.

    Zhang, Y. et al. Dedifferentiation and proliferation of mammalian cardiomyocytes. PLoS ONE 5, e12559 (2010).

  19. 19.

    Senyo, S. E. et al. Mammalian heart renewal by pre-existing cardiomyocytes. Nature 493, 433–436 (2013).

  20. 20.

    Mollova, M. et al. Cardiomyocyte proliferation contributes to heart growth in young humans. Proc. Natl Acad. Sci. USA 110, 1446–1451 (2013).

  21. 21.

    Porrello, E. R. et al. Transient regenerative potential of the neonatal mouse heart. Science 331, 1078–1080 (2011).

  22. 22.

    Haubner, B. J. et al. Complete cardiac regeneration in a mouse model of myocardial infarction. Aging (Albany NY) 4, 966–977 (2012).

  23. 23.

    Porrello, E. R. et al. Regulation of neonatal and adult mammalian heart regeneration by the miR-15 family. Proc. Natl Acad. Sci. USA 110, 187–192 (2013).

  24. 24.

    Darehzereshki, A. et al. Differential regenerative capacity of neonatal mouse hearts after cryoinjury. Dev. Biol. 399, 91–99 (2015).

  25. 25.

    Soonpaa, M. H. & Field, L. J. Survey of studies examining mammalian cardiomyocyte DNA synthesis. Circ. Res. 83, 15–26 (1998).

  26. 26.

    Patterson, M. et al. Frequency of mononuclear diploid cardiomyocytes underlies natural variation in heart regeneration. Nat. Genet. 49, 1346–1353 (2017).

  27. 27.

    Gonzalez-Rosa, J. M. et al. Myocardial polyploidization creates a barrier to heart regeneration in zebrafish. Dev. Cell 44, 433–446.e7 (2018).

  28. 28.

    Cano-Martinez, A. et al. Functional and structural regeneration in the axolotl heart (Ambystoma mexicanum) after partial ventricular amputation. Arch. Cardiol. Mex. 80, 79–86 (2010).

  29. 29.

    Mercer, S. E., Odelberg, S. J. & Simon, H. G. A dynamic spatiotemporal extracellular matrix facilitates epicardial-mediated vertebrate heart regeneration. Dev. Biol. 382, 457–469 (2013).

  30. 30.

    Chablais, F., Veit, J., Rainer, G. & Jazwinska, A. The zebrafish heart regenerates after cryoinjury-induced myocardial infarction. BMC Dev. Biol. 11, 21 (2011).

  31. 31.

    Wang, J. et al. The regenerative capacity of zebrafish reverses cardiac failure caused by genetic cardiomyocyte depletion. Development 138, 3421–3430 (2011).

  32. 32.

    Goldman, J. A. et al. Resolving heart regeneration by replacement histone profiling. Dev. Cell 40, 392–404.e5 (2017).

  33. 33.

    Vivien, C. J., Hudson, J. E. & Porrello, E. R. Evolution, comparative biology and ontogeny of vertebrate heart regeneration. NPJ Regen. Med. 1, 16012 (2016).

  34. 34.

    Gonzalez-Rosa, J. M., Burns, C. E. & Burns, C. G. Zebrafish heart regeneration: 15 years of discoveries. Regeneration (Oxf.) 4, 105–123 (2017).

  35. 35.

    Hui, S. P. et al. Zebrafish regulatory T cells mediate organ-specific regenerative programs. Dev. Cell 43, 659–672.e5 (2017).

  36. 36.

    Mahmoud, A. I. et al. Nerves regulate cardiomyocyte proliferation and heart regeneration. Dev. Cell 34, 387–399 (2015).

  37. 37.

    Gonzalez-Rosa, J. M., Peralta, M. & Mercader, N. Pan-epicardial lineage tracing reveals that epicardium derived cells give rise to myofibroblasts and perivascular cells during zebrafish heart regeneration. Dev. Biol. 370, 173–186 (2012).

  38. 38.

    Jopling, C. et al. Zebrafish heart regeneration occurs by cardiomyocyte dedifferentiation and proliferation. Nature 464, 606–609 (2010).

  39. 39.

    Choi, W. Y. et al. In vivo monitoring of cardiomyocyte proliferation to identify chemical modifiers of heart regeneration. Development 140, 660–666 (2013).

  40. 40.

    Kikuchi, K. et al. Retinoic acid production by endocardium and epicardium is an injury response essential for zebrafish heart regeneration. Dev. Cell 20, 397–404 (2011).

  41. 41.

    Kim, J. et al. PDGF signaling is required for epicardial function and blood vessel formation in regenerating zebrafish hearts. Proc. Natl Acad. Sci. USA 107, 17206–17210 (2010).

  42. 42.

    Kurkiewicz, T. O. Histogenezie miesna sur cowego zwierzat kregowych — Zur Histogenese des Herzmuskels der Wilbertiere. Bull. Int. Acad. Sci. Cracov. 148–191 (1909).

  43. 43.

    Manasek, F. J. Embryonic development of the heart. I. A light and electron microscopic study of myocardial development in the early chick embryo. J. Morphol. 125, 329–365 (1968).

  44. 44.

    Manasek, F. J. Embryonic development of the heart. II. Formation of the epicardium. J. Embryol. Exp. Morphol. 22, 333–348 (1969).

  45. 45.

    Manner, J. The development of pericardial villi in the chick embryo. Anat. Embryol. (Berl.) 186, 379–385 (1992).

  46. 46.

    Manner, J. Experimental study on the formation of the epicardium in chick embryos. Anat. Embryol. (Berl.) 187, 281–289 (1993).

  47. 47.

    Serluca, F. C. Development of the proepicardial organ in the zebrafish. Dev. Biol. 315, 18–27 (2008).

  48. 48.

    Nesbitt, T. et al. Epicardial development in the rat: a new perspective. Microsc. Microanal. 12, 390–398 (2006).

  49. 49.

    Komiyama, M., Ito, K. & Shimada, Y. Origin and development of the epicardium in the mouse embryo. Anat. Embryol. (Berl.) 176, 183–189 (1987).

  50. 50.

    Jahr, M., Schlueter, J., Brand, T. & Manner, J. Development of the proepicardium in Xenopus laevis. Dev. Dyn. 237, 3088–3096 (2008).

  51. 51.

    Hirakow, R. Epicardial formation in staged human embryos. Kaibogaku Zasshi 67, 616–622 (1992).

  52. 52.

    Fransen, M. E. & Lemanski, L. F. Epicardial development in the axolotl, Ambystoma mexicanum. Anat. Rec. 226, 228–236 (1990).

  53. 53.

    Risebro, C. A., Vieira, J. M., Klotz, L. & Riley, P. R. Characterisation of the human embryonic and foetal epicardium during heart development. Development 142, 3630–3636 (2015).

  54. 54.

    Maya-Ramos, L., Cleland, J., Bressan, M. & Mikawa, T. Induction of the Proepicardium. J. Dev. Biol. 1, 82–91 (2013).

  55. 55.

    Peralta, M. et al. Heartbeat-driven pericardiac fluid forces contribute to epicardium morphogenesis. Current Biology 23, 1726–1735 (2013).

  56. 56.

    Nahirney, P. C., Mikawa, T. & Fischman, D. A. Evidence for an extracellular matrix bridge guiding proepicardial cell migration to the myocardium of chick embryos. Dev. Dyn. 227, 511–523 (2003).

  57. 57.

    Rodgers, L. S., Lalani, S., Runyan, R. B. & Camenisch, T. D. Differential growth and multicellular villi direct proepicardial translocation to the developing mouse heart. Dev. Dyn. 237, 145–152 (2008).

  58. 58.

    Plavicki, J. S. et al. Multiple modes of proepicardial cell migration require heartbeat. BMC Dev. Biol. 14, 18 (2014).

  59. 59.

    Lie-Venema, H. et al. Origin, fate, and function of epicardium-derived cells (EPDCs) in normal and abnormal cardiac development. ScientificWorldJournal 7, 1777–1798 (2007).

  60. 60.

    Mikawa, T. & Fischman, D. A. Retroviral analysis of cardiac morphogenesis: discontinuous formation of coronary vessels. Proc. Natl Acad. Sci. USA 89, 9504–9508 (1992).

  61. 61.

    Manner, J. Does the subepicardial mesenchyme contribute myocardioblasts to the myocardium of the chick embryo heart? A quail-chick chimera study tracing the fate of the epicardial primordium. Anat. Rec. 255, 212–226 (1999).

  62. 62.

    Mikawa, T. & Gourdie, R. G. Pericardial mesoderm generates a population of coronary smooth muscle cells migrating into the heart along with ingrowth of the epicardial organ. Dev. Biol. 174, 221–232 (1996).

  63. 63.

    Perez-Pomares, J. M. et al. Experimental studies on the spatiotemporal expression of WT1 and RALDH2 in the embryonic avian heart: a model for the regulation of myocardial and valvuloseptal development by epicardially derived cells (EPDCs). Dev. Biol. 247, 307–326 (2002).

  64. 64.

    Guadix, J. A., Carmona, R., Munoz-Chapuli, R. & Perez-Pomares, J. M. In vivo and in vitro analysis of the vasculogenic potential of avian proepicardial and epicardial cells. Dev. Dyn. 235, 1014–1026 (2006).

  65. 65.

    Dettman, R. W., Denetclaw, W. Jr, Ordahl, C. P. & Bristow, J. Common epicardial origin of coronary vascular smooth muscle, perivascular fibroblasts, and intermyocardial fibroblasts in the avian heart. Dev. Biol. 193, 169–181 (1998).

  66. 66.

    Perez-Pomares, J. M. et al. Origin of coronary endothelial cells from epicardial mesothelium in avian embryos. Int. J. Dev. Biol. 46, 1005–1013 (2002).

  67. 67.

    Gittenberger-de Groot, A. C., Vrancken Peeters, M. P., Mentink, M. M., Gourdie, R. G. & Poelmann, R. E. Epicardium-derived cells contribute a novel population to the myocardial wall and the atrioventricular cushions. Circ. Res. 82, 1043–1052 (1998).

  68. 68.

    Cai, C. L. et al. A myocardial lineage derives from Tbx18 epicardial cells. Nature 454, 104–108 (2008).

  69. 69.

    Zhou, B. et al. Epicardial progenitors contribute to the cardiomyocyte lineage in the developing heart. Nature 454, 109–113 (2008).

  70. 70.

    Rudat, C. & Kispert, A. Wt1 and epicardial fate mapping. Circ. Res. 111, 165–169 (2012).

  71. 71.

    Christoffels, V. M. et al. Tbx18 and the fate of epicardial progenitors. Nature 458, E8–E9 (2009).

  72. 72.

    Katz, T. C. et al. Distinct compartments of the proepicardial organ give rise to coronary vascular endothelial cells. Dev. Cell 22, 639–650 (2012).

  73. 73.

    Braitsch, C. M., Kanisicak, O., van Berlo, J. H., Molkentin, J. D. & Yutzey, K. E. Differential expression of embryonic epicardial progenitor markers and localization of cardiac fibrosis in adult ischemic injury and hypertensive heart disease. J. Mol. Cell. Cardiol. 65, 108–119 (2013).

  74. 74.

    Zhou, B., von Gise, A., Ma, Q., Rivera-Feliciano, J. & Pu, W. T. Nkx2-5- and Isl1-expressing cardiac progenitors contribute to proepicardium. Biochem. Biophys. Res. Commun. 375, 450–453 (2008).

  75. 75.

    Braitsch, C. M. & Yutzey, K. E. Transcriptional control of cell lineage development in epicardium-derived cells. J. Dev. Biol. 1, 92–111 (2013).

  76. 76.

    Bersell, K. et al. Moderate and high amounts of tamoxifen in alphaMHC-MerCreMer mice induce a DNA damage response, leading to heart failure and death. Dis. Model. Mech. 6, 1459–1469 (2013).

  77. 77.

    Lafontant, P. J. et al. Cardiac myocyte diversity and a fibroblast network in the junctional region of the zebrafish heart revealed by transmission and serial block-face scanning electron microscopy. PLoS ONE 8, e72388 (2013).

  78. 78.

    Patel, S. H. et al. Low-dose tamoxifen treatment in juvenile males has long-term adverse effects on the reproductive system: implications for inducible transgenics. Sci. Rep. 7, 8991 (2017).

  79. 79.

    Smith, L. Good planning and serendipity: exploiting the Cre/Lox system in the testis. Reproduction 141, 151–161 (2011).

  80. 80.

    McLellan, M. A., Rosenthal, N. A. & Pinto, A. R. Cre-loxP-mediated recombination: general principles and experimental considerations. Curr. Protoc. Mouse Biol. 7, 1–12 (2017).

  81. 81.

    Song, A. J. & Palmiter, R. D. Detecting and avoiding problems when using the Cre-lox system. Trends Genet. 34, 333–340 (2018).

  82. 82.

    Ali, S. R. et al. Developmental heterogeneity of cardiac fibroblasts does not predict pathological proliferation and activation. Circ. Res. 115, 625–635 (2014).

  83. 83.

    Acharya, A. et al. The bHLH transcription factor Tcf21 is required for lineage-specific EMT of cardiac fibroblast progenitors. Development 139, 2139–2149 (2012).

  84. 84.

    Grieskamp, T., Rudat, C., Ludtke, T. H., Norden, J. & Kispert, A. Notch signaling regulates smooth muscle differentiation of epicardium-derived cells. Circ. Res. 108, 813–823 (2011).

  85. 85.

    Volz, K. S. et al. Pericytes are progenitors for coronary artery smooth muscle. eLife 4, e10036 (2015).

  86. 86.

    Yamaguchi, Y. et al. Adipogenesis and epicardial adipose tissue: a novel fate of the epicardium induced by mesenchymal transformation and PPARgamma activation. Proc. Natl Acad. Sci. USA 112, 2070–2075 (2015).

  87. 87.

    Zhou, B. et al. Thymosin beta 4 treatment after myocardial infarction does not reprogram epicardial cells into cardiomyocytes. J. Mol. Cell. Cardiol. 52, 43–47 (2012).

  88. 88.

    van Wijk, B., Gunst, Q. D., Moorman, A. F. & van den Hoff, M. J. Cardiac regeneration from activated epicardium. PLoS ONE 7, e44692 (2012).

  89. 89.

    Dube, K. N. et al. Recapitulation of developmental mechanisms to revascularize the ischemic heart. JCI Insight 2, 96800 (2017).

  90. 90.

    Zangi, L. et al. Modified mRNA directs the fate of heart progenitor cells and induces vascular regeneration after myocardial infarction. Nat. Biotechnol. 31, 898–907 (2013).

  91. 91.

    Travers, J. G., Kamal, F. A., Robbins, J., Yutzey, K. E. & Blaxall, B. C. Cardiac fibrosis: the fibroblast awakens. Circ. Res. 118, 1021–1040 (2016).

  92. 92.

    Fang, M., Xiang, F. L., Braitsch, C. M. & Yutzey, K. E. Epicardium-derived fibroblasts in heart development and disease. J. Mol. Cell. Cardiol. 91, 23–27 (2016).

  93. 93.

    Moore-Morris, T., Guimaraes-Camboa, N., Yutzey, K. E., Puceat, M. & Evans, S. M. Cardiac fibroblasts: from development to heart failure. J. Mol. Med. (Berl.) 93, 823–830 (2015).

  94. 94.

    Ieda, M. et al. Direct reprogramming of fibroblasts into functional cardiomyocytes by defined factors. Cell 142, 375–386 (2010).

  95. 95.

    Song, K. et al. Heart repair by reprogramming non-myocytes with cardiac transcription factors. Nature 485, 599–604 (2012).

  96. 96.

    Qian, L. et al. In vivo reprogramming of murine cardiac fibroblasts into induced cardiomyocytes. Nature 485, 593–598 (2012).

  97. 97.

    Zhao, Y. et al. High-efficiency reprogramming of fibroblasts into cardiomyocytes requires suppression of pro-fibrotic signalling. Nat. Commun. 6, 8243 (2015).

  98. 98.

    Cao, N. et al. Conversion of human fibroblasts into functional cardiomyocytes by small molecules. Science 352, 1216–1220 (2016).

  99. 99.

    Hashimoto, H., Olson, E. N. & Bassel-Duby, R. Therapeutic approaches for cardiac regeneration and repair. Nat. Rev. Cardiol. https://doi.org/10.1038/s41569-018-0036-6 (2018).

  100. 100.

    Forte, E., Furtado, M. & Rosenthal, N. The interstitium in cardiac repair: role of the immune–stromal cell interplay. Nat. Rev. Cardiol. (in press).

  101. 101.

    Duim, S. N., Kurakula, K., Goumans, M. J. & Kruithof, B. P. Cardiac endothelial cells express Wilms’ tumor-1: Wt1 expression in the developing, adult and infarcted heart. J. Mol. Cell. Cardiol. 81, 127–135 (2015).

  102. 102.

    Zangi, L. et al. Insulin-like growth factor 1 receptor-dependent pathway drives epicardial adipose tissue formation after myocardial injury. Circulation 135, 59–72 (2017).

  103. 103.

    Liu, Q. et al. Epicardium-to-fat transition in injured heart. Cell Res. 24, 1367–1369 (2014).

  104. 104.

    He, L. et al. Enhancing the precision of genetic lineage tracing using dual recombinases. Nat. Med. 23, 1488–1498 (2017).

  105. 105.

    Schnabel, K., Wu, C. C., Kurth, T. & Weidinger, G. Regeneration of cryoinjury induced necrotic heart lesions in zebrafish is associated with epicardial activation and cardiomyocyte proliferation. PLoS ONE 6, e18503 (2011).

  106. 106.

    Cao, J. et al. Single epicardial cell transcriptome sequencing identifies caveolin 1 as an essential factor in zebrafish heart regeneration. Development 143, 232–243 (2016).

  107. 107.

    Poon, K. L., Liebling, M., Kondrychyn, I., Garcia-Lecea, M. & Korzh, V. Zebrafish cardiac enhancer trap lines: new tools for in vivo studies of cardiovascular development and disease. Dev. Dyn. 239, 914–926 (2010).

  108. 108.

    Wu, C. C. et al. Spatially resolved genome-wide transcriptional profiling identifies BMP signaling as essential regulator of zebrafish cardiomyocyte regeneration. Dev. Cell 36, 36–49 (2016).

  109. 109.

    Lane, E. B., Hogan, B. L., Kurkinen, M. & Garrels, J. I. Co-expression of vimentin and cytokeratins in parietal endoderm cells of early mouse embryo. Nature 303, 701–704 (1983).

  110. 110.

    Zeisberg, E. M. et al. Endothelial-to-mesenchymal transition contributes to cardiac fibrosis. Nat. Med. 13, 952–961 (2007).

  111. 111.

    Tournoij, E. et al. Mlck1a is expressed in zebrafish thrombocytes and is an essential component of thrombus formation. J. Thromb. Haemost. 8, 588–595 (2010).

  112. 112.

    Bollini, S. et al. Re-activated adult epicardial progenitor cells are a heterogeneous population molecularly distinct from their embryonic counterparts. Stem Cells Dev. 23, 1719–1730 (2014).

  113. 113.

    Jaitin, D. A. et al. Massively parallel single-cell RNA-seq for marker-free decomposition of tissues into cell types. Science 343, 776–779 (2014).

  114. 114.

    Tang, F. et al. mRNA-Seq whole-transcriptome analysis of a single cell. Nat. Methods 6, 377–382 (2009).

  115. 115.

    Haber, A. L. et al. A single-cell survey of the small intestinal epithelium. Nature 551, 333–339 (2017).

  116. 116.

    Macosko, E. Z. et al. Highly parallel genome-wide expression profiling of individual cells using nanoliter droplets. Cell 161, 1202–1214 (2015).

  117. 117.

    Athanasiadis, E. I. et al. Single-cell RNA-sequencing uncovers transcriptional states and fate decisions in haematopoiesis. Nat. Commun. 8, 2045 (2017).

  118. 118.

    Wills, A. A., Holdway, J. E., Major, R. J. & Poss, K. D. Regulated addition of new myocardial and epicardial cells fosters homeostatic cardiac growth and maintenance in adult zebrafish. Development 135, 183–192 (2008).

  119. 119.

    Porrello, E. R. & Olson, E. N. A neonatal blueprint for cardiac regeneration. Stem Cell Res. 13, 556–570 (2014).

  120. 120.

    Vieira, J. M. et al. BRG1-SWI/SNF-dependent regulation of the Wt1 transcriptional landscape mediates epicardial activity during heart development and disease. Nat. Commun. 8, 16034 (2017).

  121. 121.

    Ramjee, V. et al. Epicardial YAP/TAZ orchestrate an immunosuppressive response following myocardial infarction. J. Clin. Invest. 127, 899–911 (2017).

  122. 122.

    Stevens, S. M., von Gise, A., VanDusen, N., Zhou, B. & Pu, W. T. Epicardium is required for cardiac seeding by yolk sac macrophages, precursors of resident macrophages of the adult heart. Dev. Biol. 413, 153–159 (2016).

  123. 123.

    Pinto, A. R., Godwin, J. W. & Rosenthal, N. A. Macrophages in cardiac homeostasis, injury responses and progenitor cell mobilisation. Stem Cell Res. 13, 705–714 (2014).

  124. 124.

    Karra, R. & Poss, K. D. Redirecting cardiac growth mechanisms for therapeutic regeneration. J. Clin. Invest. 127, 427–436 (2017).

  125. 125.

    Foglia, M. J. & Poss, K. D. Building and re-building the heart by cardiomyocyte proliferation. Development 143, 729–740 (2016).

  126. 126.

    Furtado, M. B., Nim, H. T., Boyd, S. E. & Rosenthal, N. A. View from the heart: cardiac fibroblasts in development, scarring and regeneration. Development 143, 387–397 (2016).

  127. 127.

    Olivey, H. E. & Svensson, E. C. Epicardial-myocardial signaling directing coronary vasculogenesis. Circ. Res. 106, 818–832 (2010).

  128. 128.

    Smart, N. & Riley, P. R. The epicardium as a candidate for heart regeneration. Future Cardiol. 8, 53–69 (2012).

  129. 129.

    Limana, F. et al. Myocardial infarction induces embryonic reprogramming of epicardial c-kit+ cells: role of the pericardial fluid. J. Mol. Cell. Cardiol. 48, 609–618 (2010).

  130. 130.

    Merki, E. et al. Epicardial retinoid X receptor alpha is required for myocardial growth and coronary artery formation. Proc. Natl Acad. Sci. USA 102, 18455–18460 (2005).

  131. 131.

    Zhao, T., Zhao, W., Chen, Y., Ahokas, R. A. & Sun, Y. Acidic and basic fibroblast growth factors involved in cardiac angiogenesis following infarction. Int. J. Cardiol. 152, 307–313 (2011).

  132. 132.

    Itoh, N., Ohta, H., Nakayama, Y. & Konishi, M. Roles of FGF signals in heart development, health, and disease. Front. Cell Dev. Biol. 4, 110 (2016).

  133. 133.

    Itoh, N. & Ohta, H. Pathophysiological roles of FGF signaling in the heart. Front. Physiol. 4, 247 (2013).

  134. 134.

    Chablais, F. & Jazwinska, A. The regenerative capacity of the zebrafish heart is dependent on TGFbeta signaling. Development 139, 1921–1930 (2012).

  135. 135.

    Vilahur, G. et al. Molecular and cellular mechanisms involved in cardiac remodeling after acute myocardial infarction. J. Mol. Cell. Cardiol. 50, 522–533 (2011).

  136. 136.

    Hao, J. et al. Elevation of expression of Smads 2, 3, and 4, decorin and TGF-beta in the chronic phase of myocardial infarct scar healing. J. Mol. Cell. Cardiol. 31, 667–678 (1999).

  137. 137.

    Deten, A., Holzl, A., Leicht, M., Barth, W. & Zimmer, H. G. Changes in extracellular matrix and in transforming growth factor beta isoforms after coronary artery ligation in rats. J. Mol. Cell. Cardiol. 33, 1191–1207 (2001).

  138. 138.

    Frangogiannis, N. G. The role of transforming growth factor (TGF)-beta in the infarcted myocardium. J. Thorac. Dis. 9, S52–S63 (2017).

  139. 139.

    Dogra, D. et al. Opposite effects of Activin type 2 receptor ligands on cardiomyocyte proliferation during development and repair. Nat. Commun. 8, 1902 (2017).

  140. 140.

    Zhao, L. et al. Notch signaling regulates cardiomyocyte proliferation during zebrafish heart regeneration. Proc. Natl Acad. Sci. USA 111, 1403–1408 (2014).

  141. 141.

    Munch, J., Grivas, D., Gonzalez-Rajal, A., Torregrosa-Carrion, R. & de la Pompa, J. L. Notch signalling restricts inflammation and serpine1 expression in the dynamic endocardium of the regenerating zebrafish heart. Development 144, 1425–1440 (2017).

  142. 142.

    Russell, J. L. et al. A dynamic notch injury response activates epicardium and contributes to fibrosis repair. Circ. Res. 108, 51–59 (2011).

  143. 143.

    Kratsios, P. et al. Distinct roles for cell-autonomous Notch signaling in cardiomyocytes of the embryonic and adult heart. Circ. Res. 106, 559–572 (2010).

  144. 144.

    Karra, R., Knecht, A. K., Kikuchi, K. & Poss, K. D. Myocardial NF-kappaB activation is essential for zebrafish heart regeneration. Proc. Natl Acad. Sci. USA 112, 13255–13260 (2015).

  145. 145.

    Zymek, P. et al. The role of platelet-derived growth factor signaling in healing myocardial infarcts. J. Am. Coll. Cardiol. 48, 2315–2323 (2006).

  146. 146.

    Duan, J. et al. Wnt1/betacatenin injury response activates the epicardium and cardiac fibroblasts to promote cardiac repair. EMBO J. 31, 429–442 (2012).

  147. 147.

    Paik, D. T. et al. Wnt10b gain-of-function improves cardiac repair by arteriole formation and attenuation of fibrosis. Circ. Res. 117, 804–816 (2015).

  148. 148.

    Sugimoto, K., Hui, S. P., Sheng, D. Z. & Kikuchi, K. Dissection of zebrafish shha function using site-specific targeting with a Cre-dependent genetic switch. eLife 6, e24635 (2017).

  149. 149.

    Wang, J., Cao, J., Dickson, A. L. & Poss, K. D. Epicardial regeneration is guided by cardiac outflow tract and Hedgehog signalling. Nature 522, 226–230 (2015).

  150. 150.

    Lavine, K. J. & Ornitz, D. M. Fibroblast growth factors and Hedgehogs: at the heart of the epicardial signaling center. Trends Genet. 24, 33–40 (2008).

  151. 151.

    Dunaeva, M. & Waltenberger, J. Hh signaling in regeneration of the ischemic heart. Cell. Mol. Life Sci. 74, 3481–3490 (2017).

  152. 152.

    Lavine, K. J. & Ornitz, D. M. Rebuilding the coronary vasculature: hedgehog as a new candidate for pharmacologic revascularization. Trends Cardiovasc. Med. 17, 77–83 (2007).

  153. 153.

    Huang, Y. et al. Igf signaling is required for cardiomyocyte proliferation during zebrafish heart development and regeneration. PLoS ONE 8, e67266 (2013).

  154. 154.

    Pachori, A. S. et al. Bone morphogenetic protein 4 mediates myocardial ischemic injury through JNK-dependent signaling pathway. J. Mol. Cell. Cardiol. 48, 1255–1265 (2010).

  155. 155.

    Leach, J. P. et al. Hippo pathway deficiency reverses systolic heart failure after infarction. Nature 550, 260–264 (2017).

  156. 156.

    Morikawa, Y., Heallen, T., Leach, J., Xiao, Y. & Martin, J. F. Dystrophin-glycoprotein complex sequesters Yap to inhibit cardiomyocyte proliferation. Nature 547, 227–231 (2017).

  157. 157.

    Xin, M. et al. Hippo pathway effector Yap promotes cardiac regeneration. Proc. Natl Acad. Sci. USA 110, 13839–13844 (2013).

  158. 158.

    Xin, M. et al. Regulation of insulin-like growth factor signaling by Yap governs cardiomyocyte proliferation and embryonic heart size. Sci. Signal. 4, ra70 (2011).

  159. 159.

    von Gise, A. et al. YAP1, the nuclear target of Hippo signaling, stimulates heart growth through cardiomyocyte proliferation but not hypertrophy. Proc. Natl Acad. Sci. USA 109, 2394–2399 (2012).

  160. 160.

    Singh, A. et al. Hippo signaling mediators Yap and Taz are required in the epicardium for coronary vasculature development. Cell Rep. 15, 1384–1393 (2016).

  161. 161.

    Xiao, Y. et al. Hippo signaling plays an essential role in cell state transitions during cardiac fibroblast development. Dev. Cell 45, 153–169.e6 (2018).

  162. 162.

    Itou, J. et al. Migration of cardiomyocytes is essential for heart regeneration in zebrafish. Development 139, 4133–4142 (2012).

  163. 163.

    Harrison, M. R. et al. Chemokine-guided angiogenesis directs coronary vasculature formation in zebrafish. Dev. Cell 33, 442–454 (2015).

  164. 164.

    Bersell, K., Arab, S., Haring, B. & Kuhn, B. Neuregulin1/ErbB4 signaling induces cardiomyocyte proliferation and repair of heart injury. Cell 138, 257–270 (2009).

  165. 165.

    Parodi, E. M. & Kuhn, B. Signalling between microvascular endothelium and cardiomyocytes through neuregulin. Cardiovasc. Res. 102, 194–204 (2014).

  166. 166.

    Gemberling, M., Karra, R., Dickson, A. L. & Poss, K. D. Nrg1 is an injury-induced cardiomyocyte mitogen for the endogenous heart regeneration program in zebrafish. eLife https://doi.org/10.7554/eLife.05871 (2015).

  167. 167.

    Kang, J. et al. Modulation of tissue repair by regeneration enhancer elements. Nature 532, 201–206 (2016).

  168. 168.

    Bock-Marquette, I. et al. Thymosin beta4 mediated PKC activation is essential to initiate the embryonic coronary developmental program and epicardial progenitor cell activation in adult mice in vivo. J. Mol. Cell. Cardiol. 46, 728–738 (2009).

  169. 169.

    Wei, K. et al. Epicardial FSTL1 reconstitution regenerates the adult mammalian heart. Nature 525, 479–485 (2015).

  170. 170.

    Frantz, C., Stewart, K. M. & Weaver, V. M. The extracellular matrix at a glance. J. Cell Sci. 123, 4195–4200 (2010).

  171. 171.

    George, E. L., Baldwin, H. S. & Hynes, R. O. Fibronectins are essential for heart and blood vessel morphogenesis but are dispensable for initial specification of precursor cells. Blood 90, 3073–3081 (1997).

  172. 172.

    Ieda, M. et al. Cardiac fibroblasts regulate myocardial proliferation through beta1 integrin signaling. Dev. Cell 16, 233–244 (2009).

  173. 173.

    Magnusson, M. K. & Mosher, D. F. Fibronectin: structure, assembly, and cardiovascular implications. Arterioscler. Thromb. Vasc. Biol. 18, 1363–1370 (1998).

  174. 174.

    Trinh, L. A. & Stainier, D. Y. Fibronectin regulates epithelial organization during myocardial migration in zebrafish. Dev. Cell 6, 371–382 (2004).

  175. 175.

    Dettman, R. W., Pae, S. H., Morabito, C. & Bristow, J. Inhibition of alpha4-integrin stimulates epicardial-mesenchymal transformation and alters migration and cell fate of epicardially derived mesenchyme. Dev. Biol. 257, 315–328 (2003).

  176. 176.

    Balmer, G. M. et al. Dynamic haematopoietic cell contribution to the developing and adult epicardium. Nat. Commun. 5, 4054 (2014).

  177. 177.

    Missinato, M. A., Tobita, K., Romano, N., Carroll, J. A. & Tsang, M. Extracellular component hyaluronic acid and its receptor Hmmr are required for epicardial EMT during heart regeneration. Cardiovasc. Res. 107, 487–498 (2015).

  178. 178.

    Marro, J., Pfefferli, C., de Preux Charles, A. S., Bise, T. & Jazwinska, A. Collagen XII contributes to epicardial and connective tissues in the zebrafish heart during ontogenesis and regeneration. PLoS ONE 11, e0165497 (2016).

  179. 179.

    Wehner, D. et al. Wnt signaling controls pro-regenerative Collagen XII in functional spinal cord regeneration in zebrafish. Nat. Commun. 8, 126 (2017).

  180. 180.

    Cao, J. & Poss, K. D. Explant culture of adult zebrafish hearts for epicardial regeneration studies. Nat. Protoc. 11, 872–881 (2016).

  181. 181.

    Cao, J. et al. Tension creates an endoreplication wavefront that leads regeneration of epicardial tissue. Dev. Cell 42, 600–615 (2017).

  182. 182.

    Urayama, K. et al. Prokineticin receptor-1 induces neovascularization and epicardial-derived progenitor cell differentiation. Arterioscler. Thromb. Vasc. Biol. 28, 841–849 (2008).

  183. 183.

    Ogura, Y. et al. Therapeutic impact of follistatin-like 1 on myocardial ischemic injury in preclinical models. Circulation 126, 1728–1738 (2012).

  184. 184.

    Oshima, Y. et al. Follistatin-like 1 is an Akt-regulated cardioprotective factor that is secreted by the heart. Circulation 117, 3099–3108 (2008).

  185. 185.

    Maruyama, S. et al. Follistatin-like 1 promotes cardiac fibroblast activation and protects the heart from rupture. EMBO Mol. Med. 8, 949–966 (2016).

  186. 186.

    Shimano, M. et al. Cardiac myocyte follistatin-like 1 functions to attenuate hypertrophy following pressure overload. Proc. Natl Acad. Sci. USA 108, E899–E906 (2011).

  187. 187.

    van Tuyn, J. et al. Epicardial cells of human adults can undergo an epithelial-to-mesenchymal transition and obtain characteristics of smooth muscle cells in vitro. Stem Cells 25, 271–278 (2007).

  188. 188.

    Moerkamp, A. T. et al. Human fetal and adult epicardial-derived cells: a novel model to study their activation. Stem Cell Res. Ther. 7, 174 (2016).

  189. 189.

    Witty, A. D. et al. Generation of the epicardial lineage from human pluripotent stem cells. Nat. Biotechnol. 32, 1026–1035 (2014).

  190. 190.

    Iyer, D. et al. Robust derivation of epicardium and its differentiated smooth muscle cell progeny from human pluripotent stem cells. Development 142, 1528–1541 (2015).

  191. 191.

    Guadix, J. A. et al. Human pluripotent stem cell differentiation into functional epicardial progenitor cells. Stem Cell Rep. 9, 1754–1764 (2017).

  192. 192.

    Bao, X. et al. Long-term self-renewing human epicardial cells generated from pluripotent stem cells under defined xeno-free conditions. Nat. Biomed. Eng. 1, 0003 (2016).

  193. 193.

    Zhao, J. et al. Efficient differentiation of TBX18+/WT1+ epicardial-like cells from human pluripotent stem cells using small molecular compounds. Stem Cells Dev. 26, 528–540 (2017).

  194. 194.

    Wessels, A. et al. Epicardially derived fibroblasts preferentially contribute to the parietal leaflets of the atrioventricular valves in the murine heart. Dev. Biol. 366, 111–124 (2012).

  195. 195.

    Lin, Z. & Pu, W. T. Harnessing Hippo in the heart: Hippo/Yap signaling and applications to heart regeneration and rejuvenation. Stem Cell Res. 13, 571–581 (2014).

Download references

Acknowledgements

The authors thank A. Dickson (Duke University, Durham, NC, USA) for assistance with artwork and R. Karra (Duke University, Durham, NC, USA) and J. Kang (University of Wisconsin-Madison, USA) for comments on the manuscript. The authors apologize to their colleagues whose work they could not discuss owing to space limitations. J.C. was supported by AHA postdoctoral fellowships (14POST20230023 and 16POST30230005). K.D.P. acknowledges grant support from the National Heart, Lung, and Blood Institute (NHLBI) (HL081674, HL131319, and HL136182), an AHA Merit Award, and Fondation Leducq.

Reviewer information

Nature Reviews Cardiology thanks M. J. Goumans, P. Riley, and B. Zhou for their contribution to the peer review of this work.

Author information

Affiliations

  1. Department of Cell Biology, Duke University Medical Center, Durham, NC, USA

    • Jingli Cao
    •  & Kenneth D. Poss
  2. Regeneration Next, Duke University, Durham, NC, USA

    • Jingli Cao
    •  & Kenneth D. Poss
  3. Cardiovascular Research Institute, Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY, USA

    • Jingli Cao

Authors

  1. Search for Jingli Cao in:

  2. Search for Kenneth D. Poss in:

Contributions

Both authors researched data for the article, discussed its content, wrote the manuscript, and reviewed and edited it before submission.

Competing interests

The authors declare no competing interests.

Corresponding authors

Correspondence to Jingli Cao or Kenneth D. Poss.

Glossary

Diploid

Containing two complete sets of chromosomes.

Knock-in

A genetic engineering method to insert an exogenous sequence or to replace the endogenous sequence in a given locus of the genome.

Mitogenic factors

Factors that promote cell proliferation.

In situ hybridization

A biochemical method that uses labelled complementary nucleic acids to visualize specific nucleic acid sequences in tissues.

Gene-trap line

A high-throughput method that captures the readouts of gene regulatory sequences in transgenic animals.

About this article

Publication history

Published

DOI

https://doi.org/10.1038/s41569-018-0046-4