Beneficial effects of vascular endothelial growth factor B gene transfer in aged heart

N. Manickam (Frankfurt am Main)¹, I. Sultan (Helsinki)², J. Panthel (Frankfurt am Main)³, H. Kujundzic (Frankfurt am Main)³, A. Fischer (Frankfurt am Main)⁴, K. Schmitz (Frankfurt am Main)¹, M. R. Jurado (Frankfurt am Main)¹, D. R. Morales (Frankfurt am Main)³, D. John (Frankfurt am Main)⁴, S.-F. Glaser (Frankfurt am Main)⁴, K. A. Stilz (Frankfurt am Main)¹, P. F. Malacarne (Frankfurt am Main)⁵, R. P. Brandes (Frankfurt am Main)⁶, T. Braun (Bad Nauheim)⁷, C. Lerchenmüller (Zurich)⁸, F. Betge (Heidelberg)⁹, W. Abplanalp (Frankfurt am Main)¹⁰, K. Alitalo (Helsinki)², S. Dimmeler (Frankfurt am Main)⁴, J. U. G. Wagner (Frankfurt am Main)^11
1Institute of Cardiovascular Regeneration, Centre for Molecular Medicine Department of Medicine, Goethe University Frankfurt Frankfurt am Main, Deutschland; ²University of Helsinki Translational Cancer Medicine Program Helsinki, Finnland; ³Institute of cardiovascular Regeneration Cardiovascular Regeneration Frankfurt am Main, Deutschland; ⁴Goethe Universität Frankfurt am Main Zentrum für Molekulare Medizin, Institut für Kardiovaskuläre Regeneration Frankfurt am Main, Deutschland; ⁵Institute for Cardiovascular Physiology Goethe-Universität Frankfurt am Main, Deutschland; ⁶Universitätsklinikum Frankfurt Institut für Kardiovaskuläre Physiologie Frankfurt am Main, Deutschland; ⁷Max-Planck-Institut für Herz- und Lungenforschung Bad Nauheim, Deutschland; ⁸University Hospital Zurich Department of Cardiology Zurich, Deutschland; ⁹University Hospital Heidelberg Department of Cardiology Heidelberg, Deutschland; ¹⁰Universitätsklinikum Frankfurt Zentrum für Molekulare Medizin, Institut für Kardiovaskuläre Regeneration Frankfurt am Main, Deutschland; ¹¹Goethe Universität Frankfurt am Main Institute of Cardiovascular Regeneration Frankfurt am Main, Deutschland

Aging is a major risk factor for impaired cardiovascular health. The aging myocardium is characterized by endothelial cell dysfunction, increased hypertrophy and fibrosis and electrophysiological alterations that predispose the elderly to arrhythmic risk. The mechanism of age-associated pathophysiological alterations are incompletely understood. To tackle age-related organ dysfunction, the members of the VEGF family came into focus. While VEGFA signaling has been shown to mitigate several aging-related cardiac phenotypes and prolong survival in aged mice, the role of VEGFB in cardiac aging remains underexplored. In this study, we identify a significant decline in Vegfb expression, particularly of its soluble isoform Vegfb186, in aged mouse (0.19±0.07-fold, p<0.05) and human hearts. To assess the therapeutic potential of VEGFB in aging-associated cardiac pathologies, we used AAV9-mediated gene transfer to overexpress Vegfb186 in 18-month-old male C57Bl/6J mice.

VEGFB is known to exhibit vascular and neuroprotective effects that we assessed in the ageing heart. In the aged heart, Vegfb186 overexpression that had only a modest effect on the vascular endothelium prevented age-induced diastolic dysfunction and fibrosis (0.27±0.089-fold, p<0.05). Vegfb186 treatment additionally restored sympathetic (19.18±6.280-fold, p<0.05) and tended to improve sensory nerve fiber density and increased heart rate variability (4.79±1.513-fold, p<0.05). In vitro assays confirmed the in vivo findings by showing that recombinant VEGFB blocks TGF-β2 mediated fibroblast activation. Recombinant VEGFB further does not induce axon growth in vitro but recues axon sprouting in the presence of conditioned medium from senescent endothelial cells. Although Vegfb186 overexpression induced cardiac hypertrophy (62.67±19.93-fold, p<0.05), our findings indicated that this hypertrophy was compensatory rather than pathological as Vegfb186 overexpression corrected the elevated cardiomyocyte length-to-width-ratio observed in aged hearts (0.81±0.23-fold, p<0.01), a metric typically indicative of pathological remodeling. Expression of pathological stress markers such as miR222-3p and Nppa (encoding for ANP) were not induced while Nppb was only modestly upregulated by Vegfb186 overexpression. Single-nucleus RNA sequencing of the hearts and in vitro analysis of the cardiomyocytes indicated upregulation of the STAT3 signal transduction pathway as a potential contributor of VEGFB-induced cardiac hypertrophy. Indeed, VEGFB induced cardiomyocyte hypertrophy in vitro could be blocked using STAT inhibitors.

Our findings demonstrate that Vegfb186 overexpression partially reverses age-related cardiac pathologies such as diastolic dysfunction and fibrosis. This work highlights VEGFB as a potential therapeutic target for combating cardiac aging and its associated dysfunctions.