VEGF-B Gene Therapy for the Heart: Proceed with Caution
Authors: Mauro Giacca, Fabio A. Recchia
Journal: Molecular Therapy (2020)

An unfortunate circumstance in biology is that the vascular endothelial growth factor type B (VEGF-B) was identified only after its homolog family member VEGF-A had already been discovered.1Olofsson B. Pajusola K. Kaipainen A. von Euler G. Joukov V. Saksela O. Orpana A. Pettersson R.F. Alitalo K. Eriksson U. Vascular endothelial growth factor B, a novel growth factor for endothelial cells.Proc. Natl. Acad. Sci. USA. 1996; 93: 2576-2581Crossref PubMed Scopus (622) Google Scholar Should the opposite have occurred, VEGF-B would likely not have been named as such. Indeed, VEGF-B is a poor growth factor for endothelial cells and, unlike VEGF-A, it is not angiogenic in the strict sense, while its only known main receptor, VEGFR-1, is expressed in endothelial cells as well as in a vast series of other cell types. Little was known about the non-angiogenic functions of selective VEGFR-1 ligands until a study in 2008 showed marked anti-apoptotic effects of VEGF-B, both in vitro and in vivo.2Li Y. Zhang F. Nagai N. Tang Z. Zhang S. Scotney P. Lennartsson J. Zhu C. Qu Y. Fang C. et al.VEGF-B inhibits apoptosis via VEGFR-1-mediated suppression of the expression of BH3-only protein genes in mice and rats.J. Clin. Invest. 2008; 118: 913-923Crossref PubMed Scopus (8) Google Scholar Subsequent studies confirmed cell-protective functions of this factor in different cell types. In this issue of Molecular Therapy, Lähteenvuo et al.3Lähteenvuo J. Hätinen O.P. Kuivanen A. Huusko J. Paananen J. Lähteenvuo M. Nurro J. Hedman M. Hartikainen J. Laham-Karam N. et al.Susceptibility to Cardiac Arrhythmias and Sympathetic Nerve Growth in VEGF-B Overexpressing Myocardium.Mol. Ther. 2020; 28 (this issue): 1731-1740Abstract Full Text Full Text PDF Scopus (11) Google Scholar add a new piece to the puzzle of VEGF-B activities. By using an adenoviral vector to overexpress VEGF-B186, they show that this factor induces sympathetic nerve sprouting in mouse and pig hearts via a VEGFR-1 signaling-independent mechanism. The integrity of cardiac innervation is very important for electrical stability, contractility, myocardial metabolism, and coronary function.4Jamali H.K. Waqar F. Gerson M.C. Cardiac autonomic innervation.J. Nucl. Cardiol. 2017; 24: 1558-1570Crossref PubMed Scopus (22) Google Scholar Therefore, the induction of cardiac re-innervation by the VEGF-B186 transgene should theoretically enhance post-ischemia cardiac recovery. Nonetheless, the authors report an association between a likely disordered nerve sprouting5Fukuda K. Kanazawa H. Aizawa Y. Ardell J.L. Shivkumar K. Cardiac innervation and sudden cardiac death.Circ. Res. 2015; 116: 2005-2019Crossref PubMed Scopus (211) Google Scholar and increased risk of ventricular arrhythmias and sudden cardiac death in pigs, at 6 days after infarction, unlike any other VEGFs tested in their previous studies. The authors should be commended for their rigorous approach based on retrospective analysis of 334 pigs and statistics, more usually utilized in the clinical studies realm. Such careful evaluation revealed an intrinsic risk in cardiac VEGF-B186 gene therapy, whereas pre-clinical studies, strictly prospective and necessarily based on smaller sample sizes, usually tend to overemphasize beneficial effects of experimental therapies, paying little attention to untoward events. Does the observation by Lähteenvuo et al.3Lähteenvuo J. Hätinen O.P. Kuivanen A. Huusko J. Paananen J. Lähteenvuo M. Nurro J. Hedman M. Hartikainen J. Laham-Karam N. et al.Susceptibility to Cardiac Arrhythmias and Sympathetic Nerve Growth in VEGF-B Overexpressing Myocardium.Mol. Ther. 2020; 28 (this issue): 1731-1740Abstract Full Text Full Text PDF Scopus (11) Google Scholar raise a red flag on the therapeutic utilization of VEGF-B gene transfer in the heart? Not necessarily. If the goal is angiogenesis, VEGF-A or VEGF-D are more established therapeutic factors. Despite the fact that VEGF-A binds with 10-fold greater affinity to VEGFR-1 than to its angiogenic receptor VEGFR-2, it does not appear to be arrhythmogenic. However, if the goal is rather the direct protection of cardiomyocytes and other cell types in the ischemic or non-ischemic failing heart, then strong evidence suggests that the 167 aa isoform of VEGF-B (VEGF-B167) might be an equally effective and safer candidate. VEGF-B167 is the most abundant VEGF-B isoform and is expressed in brown fat, myocardium, and skeletal muscle.6Bry M. Kivelä R. Holopainen T. Anisimov A. Tammela T. Soronen J. Silvola J. Saraste A. Jeltsch M. Korpisalo P. et al.Vascular endothelial growth factor-B acts as a coronary growth factor in transgenic rats without inducing angiogenesis, vascular leak, or inflammation.Circulation. 2010; 122: 1725-1733Crossref PubMed Scopus (116) Google Scholar Mice knocked out for this factor develop normally but exhibit a mild cardiac phenotype, with dysfunctional coronary vasculature, impaired recovery from cardiac ischemia, and, most notably, decreased heart size.7Bellomo D. Headrick J.P. Silins G.U. Paterson C.A. Thomas P.S. Gartside M. Mould A. Cahill M.M. Tonks I.D. Grimmond S.M. et al.Mice lacking the vascular endothelial growth factor-B gene (Vegfb) have smaller hearts, dysfunctional coronary vasculature, and impaired recovery from cardiac ischemia.Circ. Res. 2000; 86: E29-E35Crossref PubMed Google Scholar Our own work using adeno-associated virus (AAV)-mediated gene delivery of VEGF-A165 and VEGF-B167 in infarcted rat hearts revealed that both factors produced a marked improvement in cardiac function by promoting cardiac contractility, preserving viable cardiac tissue, and preventing remodeling of the left ventricle over time.8Zentilin L. Puligadda U. Lionetti V. Zacchigna S. Collesi C. Pattarini L. Ruozi G. Camporesi S. Sinagra G. Pepe M. et al.Cardiomyocyte VEGFR-1 activation by VEGF-B induces compensatory hypertrophy and preserves cardiac function after myocardial infarction.FASEB J. 2010; 24: 1467-1478Crossref PubMed Scopus (138) Google Scholar However, VEGF-B167 was more effective in preserving cardiac mass, even in the absence of a significant induction of angiogenesis. Two subsequent studies by our group in a dog model of tachypacing-induced dilated cardiomyopathy showed that AAV-VEGF-B167, injected directly in myocardium or infused in coronary arteries, nearly halted cardiac structural and functional abnormalities and delayed the onset of decompensated heart failure.9Pepe M. Mamdani M. Zentilin L. Csiszar A. Qanud K. Zacchigna S. Ungvari Z. Puligadda U. Moimas S. Xu X. et al.Intramyocardial VEGF-B167 gene delivery delays the progression towards congestive failure in dogs with pacing-induced dilated cardiomyopathy.Circ. Res. 2010; 106: 1893-1903Crossref PubMed Scopus (76) Google Scholar,10Woitek F. Zentilin L. Hoffman N.E. Powers J.C. Ottiger I. Parikh S. Kulczycki A.M. Hurst M. Ring N. Wang T. et al.Intracoronary Cytoprotective Gene Therapy: A Study of VEGF-B167 in a Pre-Clinical Animal Model of Dilated Cardiomyopathy.J. Am. Coll. Cardiol. 2015; 66: 139-153Crossref PubMed Scopus (50) Google Scholar Lähteenvuo et al.3Lähteenvuo J. Hätinen O.P. Kuivanen A. Huusko J. Paananen J. Lähteenvuo M. Nurro J. Hedman M. Hartikainen J. Laham-Karam N. et al.Susceptibility to Cardiac Arrhythmias and Sympathetic Nerve Growth in VEGF-B Overexpressing Myocardium.Mol. Ther. 2020; 28 (this issue): 1731-1740Abstract Full Text Full Text PDF Scopus (11) Google Scholar rightly observe that tachypacing might mask possible ventricular arrhythmias. However, our ongoing clinical trial in dogs with severe spontaneous heart failure is not revealing unexpected increases in sudden death after VEGF-B167 gene delivery to the heart and, on the contrary, some canine patients monitored for months have displayed a surprising prolongation of life expectancy (unpublished data). Over the last several years, there has been considerable interest in understanding the role of VEGF-B in the heart. Despite not being angiogenic in the strict sense, transgenically overexpressed VEGF-B was shown to induce overgrowth of the epicardial coronary vessels and of their main branches.6Bry M. Kivelä R. Holopainen T. Anisimov A. Tammela T. Soronen J. Silvola J. Saraste A. Jeltsch M. Korpisalo P. et al.Vascular endothelial growth factor-B acts as a coronary growth factor in transgenic rats without inducing angiogenesis, vascular leak, or inflammation.Circulation. 2010; 122: 1725-1733Crossref PubMed Scopus (116) Google Scholar In addition, this factor was reported to regulate metabolism by promoting endothelial uptake and transcytosis of fatty acids from the bloodstream into various tissues, including myocardium,11Hagberg C.E. Falkevall A. Wang X. Larsson E. Huusko J. Nilsson I. van Meeteren L.A. Samen E. Lu L. Vanwildemeersch M. et al.Vascular endothelial growth factor B controls endothelial fatty acid uptake.Nature. 2010; 464: 917-921Crossref PubMed Scopus (351) Google Scholar and also to deplete endothelial plasma membrane cholesterol, with consequent reduction in glucose uptake.12Moessinger C. Nilsson I. Muhl L. Zeitelhofer M. Heller Sahlgren B. Skogsberg J. Eriksson U. VEGF-B signaling impairs endothelial glucose transcytosis by decreasing membrane cholesterol content.EMBO Rep. 2020; 2020: e49343Google Scholar Of interest, under normal conditions, VEGF-B appears to be highly expressed by cardiomyocytes themselves, from which it is secreted and binds to the surrounding extracellular matrix. Endothelium-secreted heparinase can mobilize this extracellular pool of VEGF-B, thus enabling it to exert pro-survival and protective activities.13Lal N. Chiu A.P. Wang F. Zhang D. Jia J. Wan A. Vlodavsky I. Hussein B. Rodrigues B. Loss of VEGFB and its signaling in the diabetic heart is associated with increased cell death signaling.Am. J. Physiol. Heart Circ. Physiol. 2017; 312: H1163-H1175Crossref PubMed Scopus (23) Google Scholar This protective mechanism appears to be severely attenuated in the setting of uncontrolled diabetes mellitus, which could explain the development of diabetic cardiomyopathy.13Lal N. Chiu A.P. Wang F. Zhang D. Jia J. Wan A. Vlodavsky I. Hussein B. Rodrigues B. Loss of VEGFB and its signaling in the diabetic heart is associated with increased cell death signaling.Am. J. Physiol. Heart Circ. Physiol. 2017; 312: H1163-H1175Crossref PubMed Scopus (23) Google Scholar How VEGF-B exerts its beneficial function on cardiomyocytes remains an open matter. VEGFR-1 is expressed by cardiomyocytes in a functional form at levels that are lower than those of endothelial cells but still sufficient to exert a protective effect.7Bellomo D. Headrick J.P. Silins G.U. Paterson C.A. Thomas P.S. Gartside M. Mould A. Cahill M.M. Tonks I.D. Grimmond S.M. et al.Mice lacking the vascular endothelial growth factor-B gene (Vegfb) have smaller hearts, dysfunctional coronary vasculature, and impaired recovery from cardiac ischemia.Circ. Res. 2000; 86: E29-E35Crossref PubMed Google Scholar,8Zentilin L. Puligadda U. Lionetti V. Zacchigna S. Collesi C. Pattarini L. Ruozi G. Camporesi S. Sinagra G. Pepe M. et al.Cardiomyocyte VEGFR-1 activation by VEGF-B induces compensatory hypertrophy and preserves cardiac function after myocardial infarction.FASEB J. 2010; 24: 1467-1478Crossref PubMed Scopus (138) Google Scholar In addition, this factor was also shown to influence myocardium through the activation of endothelial cells in the coronary vasculature.14Kivelä R. Hemanthakumar K.A. Vaparanta K. Robciuc M. Izumiya Y. Kidoya H. Takakura N. Peng X. Sawyer D.B. Elenius K. et al.Endothelial Cells Regulate Physiological Cardiomyocyte Growth via VEGFR2-Mediated Paracrine Signaling.Circulation. 2019; 139: 2570-2584Crossref PubMed Scopus (66) Google Scholar What are the molecular mechanisms underlying possible differences between the cardiac effects of VEGF-B186 versus VEGF-B167? They are both specific ligands of VEGFR-1 and, similar to VEGF-A165 and PlGF, bind neuropilin receptor-1 (Nrp-1),15Makinen T. Olofsson B. Karpanen T. Hellman U. Soker S. Klagsbrun M. Eriksson U. Alitalo K. Differential binding of vascular endothelial growth factor B splice and proteolytic isoforms to neuropilin-1.J. Biol. Chem. 1999; 274: 21217-21222Crossref PubMed Scopus (230) Google Scholar the receptor that seems to mediate the neurotrophic effect in the heart in the Lähteenvuo et al.3Lähteenvuo J. Hätinen O.P. Kuivanen A. Huusko J. Paananen J. Lähteenvuo M. Nurro J. Hedman M. Hartikainen J. Laham-Karam N. et al.Susceptibility to Cardiac Arrhythmias and Sympathetic Nerve Growth in VEGF-B Overexpressing Myocardium.Mol. Ther. 2020; 28 (this issue): 1731-1740Abstract Full Text Full Text PDF Scopus (11) Google Scholar study. However, VEGF-B167 and VEGF-B186 bind Nrp-1 with different modalities involving, respectively, a heparin-binding domain and proteolytic processing. Importantly, VEGF-A165 and VEGF-B167 tend to remain stably attached to heparin sulfates, while VEGF-B186 and PlGF are more freely soluble and diffusible, probably functioning also as paracrine factors. To what extent these subtle molecular differences might explain the different arrhythmogenic potential of the two VEGF-B isoforms in the absence of VEGFR-1 binding remains a matter for interesting, future investigation. This appears to be an important field of research, since the marked beneficial effect of VEGF-B on the heart continues to be very attractive for the development of clinically effective gene therapy for heart failure. This work was supported by the European Research Council (ERC; Advanced Grant 787971 "CuRE"), the British Heart Foundation (BHF; Programme Grant RG/19/11/34633), the European Commission Horizon 2020 programme (grant 874764 "REANIMA"), and the NIH (grant HL129120). Susceptibility to Cardiac Arrhythmias and Sympathetic Nerve Growth in VEGF-B Overexpressing MyocardiumLähteenvuo et al.Molecular TherapyMarch 18, 2020In BriefVEGF-B gene therapy is a promising proangiogenic treatment for ischemic heart disease. However, the immunostaining showed a significant increase in the number of nerves and an abnormal nerve distribution in αMHC-VEGF-B mice, and the AdVEGF-B186 gene transferred pig myocardium, making them more susceptible to arrhythmias and even sudden cardiac death. 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