Vascular endothelial growth factor enhances profibrotic activities through modulation of calcium homeostasis in human atrial fibroblasts

Development of a Silk Fibroin-Small Intestinal Submucosa Small-Diameter Vascular Graft with Sequential VEGF and TGF-β1 Inhibitor Delivery for In Situ Tissue Engineering

Proper endothelialization and limited collagen deposition on the luminal surface after graft implantation plays a crucial role to prevent the occurrence of stenosis. To achieve these conditions, a biodegradable graft with adequate mechanical properties and the ability to sequentially deliver therapeutic agents isfabricated. In this study, a dual-release system is constructed through coaxial electrospinning by incorporating recombinant human vascular endothelial growth factor (VEGF) and transforming growth factor β1 (TGF-β1) inhibitor into silk fibroin (SF) nanofibers to form a bioactive membrane. The functionalized SF membrane as the inner layer of the graft is characterized by the release profile, cell proliferation and protein expression. It presents excellent biocompatibility and biodegradation, facilitating cell attachment, proliferation, and infiltration. The core-shell structure enables rapid VEGF release within 10 days and sustained plasmid delivery for 21 days. A 2.0-mm-diameter vascular graft is fabricated by integrating the SF membrane with decellularized porcine small intestinal submucosa (SIS), aiming to facilitate the integration process under a stable extracellular matrix structure. The bioengineered graft is functionalized with the sequential administration of VEGF and TGF-β1, and with the reinforced and compatible mechanical properties, thereby offers an orchestrated solution for stenosis with potential for in situ vascular tissue engineering applications.

Human Macrophages Polarized by Interaction with Apoptotic Cells Produce Fibrosis-Associated Mediators and Enhance Pro-Fibrotic Activity of Dermal Fibroblasts In Vitro

Apoptosis and subsequent removal of dead cells are an essential part of wound healing. Macrophages phagocytize apoptotic cells (efferocytosis) and contribute to the resolution of inflammation. However, their participation in fibrogenesis and the mechanisms of influence on this process remain unclear. In the present study, we focused on the fibrogenic properties of human monocyte-derived macrophages polarized in the M2 direction by interaction with apoptotic cells. We studied their influence on the proliferation ([3H]-thymidine incorporation), differentiation (by the expression of α-SMA, a myofibroblast marker) and collagen-producing activity (ELISA) of dermal fibroblasts compared to classically (LPS) and alternatively (IL-4) activated macrophages. Macrophages polarized by the interaction with apoptotic cells had a unique phenotype and profile of produced factors and differed from the compared macrophage subtypes. Their conditioned media promoted the proliferation of dermal fibroblasts and the expression of α-SMA in them at the level of macrophages stimulated by IL-4, while the stimulating effect on the collagen-producing activity was more pronounced compared to that of the other macrophage subtypes. Moreover, they are characterized by the high level of production of pro-fibrotic factors such as TIMP-1, TGF-β1 and angiogenin. Taken together, M2-like macrophages polarized by efferocytosis demonstrate in vitro pro-fibrotic activity by promoting the functional activity of dermal fibroblasts and producing pro-fibrotic and pro-angiogenic factors.

Comparison of the Effects of Open Surgery and Minimally Invasive Surgery on the Achilles Tendon Rupture Healing Based on Angiogenesis

Objective

To compare the effect of three different surgical methods on rabbit Achilles tendon rupture.

Methods

The Achilles tendon transection model was constructed by cutting off the inner half of the Achilles tendon. Rabbits were divided into 4 groups: model group, open surgery (OS) group, minimally invasive surgery (MS) group, and conservative treatment (CT) group. Biomechanical evaluation, H&E, and Picrosirius Red staining were applied to evaluate the histological changes and healing. RT-qPCR, Western blot, ELISA, and IHC staining were used to detect the expression of COLIII, IL-1β, TNF-α, IL-6, CD31, VEGF, bFGF, and TGF-β1.

Results

Different surgery treatments significantly alleviated the histological changes in rabbits. The tension and elasticity of the Achilles tendon were significantly increased after surgery. In addition, surgery treatments notably alleviated the inflammatory responses in vivo via downregulation of IL-1β, TNF-α, and IL-6 and promoted the tube formation in tissues through upregulating VEGF, bFGF, TGF-β1, and CD31. Furthermore, MS exhibited best therapeutic efficiency on Achilles tendon rupture healing, compared with OS or CT.

Conclusions

Our research revealed the superiority of MS in Achilles tendon rupture treatment at the molecular level compared with OS or CT.

Klotho Modulates Pro-Fibrotic Activities in Human Atrial Fibroblasts through Inhibition of Phospholipase C Signaling and Suppression of Store-Operated Calcium Entry

Background: Atrial fibroblasts activation causes atrial fibrosis, which is one major pathophysiological contributor to atrial fibrillation (AF) genesis. Klotho is a pleiotropic protein with remarkable cardiovascular effects, including anti-inflammatory, anti-oxidative, and anti-apoptotic effects. This study investigated whether Klotho can modulate the activity of human atrial fibroblasts and provides an anti-fibrotic effect. Methods: Cell migration assay and proliferation assay were used to investigate fibrogenesis activities in single human atrial fibroblasts with or without treatment of Klotho (10 and 100 pM, 48 h). Calcium fluorescence imaging, the whole-cell patch-clamp, and Western blotting were performed in human atrial fibroblasts treated with and without Klotho (100 pM, 48 h) to evaluate the store-operated calcium entry (SOCE), transient receptor potential (TRP) currents, and downstream signaling. Results: High dose of Klotho (100 pM, 48 h) significantly reduced the migration of human atrial fibroblasts without alternating their proliferation; in addition, treatment of Klotho (100 pM, 48 h) also decreased SOCE and TRP currents. In the presence of BI-749327 (a selective canonical TRP 6 channel inhibitor, 1 μM, 48 h), Klotho (100 pM, 48 h) could not inhibit fibroblast migration nor suppress the TRP currents. Klotho-treated fibroblasts (100 pM, 48 h) had lower phosphorylated phospholipase C (PLC) (p-PLCβ3 Ser537) expression than the control. The PLC inhibitor, U73122 (1 μM, 48 h), reduced the migration, decreased SOCE and TRP currents, and lowered p-PLCβ3 in atrial fibroblasts, similar to Klotho. In the presence of the U73122 (1 μM, 48 h), Klotho (100 pM, 48 h) could not further modulate the migration and collagen synthesis nor suppress the TRP currents in human atrial fibroblasts. Conclusions: Klotho inhibited pro-fibrotic activities and SOCE by inhibiting the PLC signaling and suppressing the TRP currents, which may provide a novel insight into atrial fibrosis and arrhythmogenesis.

Immunomodulation of Telmisartan-Loaded PCL/PVP Scaffolds on Macrophages Promotes Endogenous Bone Regeneration

Biomaterial-immune system interactions play an important role in postimplantation osseointegration to retain the functionality of healthy and intact bones. Therefore, appropriate osteoimmunomodulation of implants has been considered and validated as an efficient strategy to alleviate inflammation and enhance new bone formation. Here, we fabricated a nanostructured PCL/PVP (polycaprolactone/polyvinylpyrrolidone) electrospinning scaffold for cell adhesion, tissue ingrowth, and bone defect padding. In addition, telmisartan, an angiotensin 2 receptor blocker with distinct immune bioactivity, was doped into PCL-/PVP-electrospun scaffolds at different proportions [1% (TPP-1), 5% (TPP-5), and 10% (TPP-10)] to investigate its immunomodulatory effects and osteoinductivity/conductivity. Telmisartan-loaded scaffolds displayed in vitro anti-inflammatory bioactivity on lipopolysaccharide-induced M1 macrophages by polarizing them to an M2-like phenotype and exhibited pro-osteogenic properties on bone marrow-derived mesenchymal stem cells (BMSCs). Histological analysis and micro-CT results of a rat skull defect model also showed that the telmisartan-loaded scaffolds induced a higher M2/M1 ratio, less inflammatory infiltration, and better bone regenerative patterns. Furthermore, activation of the BMP2 (bone morphogenetic protein-2)-Smad signaling pathway was found to be dominant in telmisartan-loaded scaffold-mediated macrophage-BMSC interactions. These findings indicate that telmisartan incorporation with PCL/PVP nanofibrous scaffolds is a potential therapeutic strategy for promoting bone healing by modulating M1 macrophages to a more M2 phenotype at early stages of postimplantation.

VEGF-D-mediated signaling in tendon cells is involved in degenerative processes

Vascular endothelial growth factor (VEGF) signaling is crucial for a large variety of cellular processes, not only related to angiogenesis but also in nonvascular cell types. We have previously shown that controlling angiogenesis by reducing VEGF-A signaling positively affects tendon healing. We now hypothesize that VEGF signaling in non-endothelial cells may contribute to tendon pathologies. By immunohistochemistry we show that VEGFR1, VEGFR2, and VEGFR3 are expressed in murine and human tendon cells in vivo. In a rat Achilles tendon defect model we show that VEGFR1, VEGFR3, and VEGF-D expression are increased after injury. On cultured rat tendon cells we show that VEGF-D stimulates cell proliferation in a dose-dependent manner; the specific VEGFR3 inhibitor SAR131675 reduces cell proliferation and cell migration. Furthermore, activation of VEGFR2 and -3 in tendon-derived cells affects the expression of mRNAs encoding extracellular matrix and matrix remodeling proteins. Using explant model systems, we provide evidence, that VEGFR3 inhibition prevents biomechanical deterioration in rat tail tendon fascicles cultured without load and attenuates matrix damage if exposed to dynamic overload in a bioreactor system. Together, these results suggest a strong role of tendon cell VEGF signaling in mediation of degenerative processes. These findings give novel insight into tendon cell biology and may pave the way for novel treatment options for degenerative tendon diseases.

Fibroblast Growth Factor 23 Stimulates Cardiac Fibroblast Activity through Phospholipase C-Mediated Calcium Signaling

Fibroblast growth factor (FGF)-23 induces hypertrophy and calcium (Ca²⁺) dysregulation in cardiomyocytes, leading to cardiac arrhythmia and heart failure. However, knowledge regarding the effects of FGF-23 on cardiac fibrogenesis remains limited. This study investigated whether FGF-23 modulates cardiac fibroblast activity and explored its underlying mechanisms. We performed MTS analysis, 5-ethynyl-2′-deoxyuridine assay, and wound-healing assay in cultured human atrial fibroblasts without and with FGF-23 (1, 5 and 25 ng/mL for 48 h) to analyze cell proliferation and migration. We found that FGF-23 (25 ng/mL, but not 1 or 5 ng/mL) increased proliferative and migratory abilities of human atrial fibroblasts. Compared to control cells, FGF-23 (25 ng/mL)-treated fibroblasts had a significantly higher Ca²⁺ entry and intracellular inositol 1,4,5-trisphosphate (IP₃) level (assessed by fura-2 ratiometric Ca²⁺ imaging and enzyme-linked immunosorbent assay). Western blot analysis showed that FGF-23 (25 ng/mL)-treated cardiac fibroblasts had higher expression levels of calcium release-activated calcium channel protein 1 (Orai1) and transient receptor potential canonical (TRPC) 1 channel, but similar expression levels of α-smooth muscle actin, collagen type IA1, collagen type Ⅲ, stromal interaction molecule 1, TRPC 3, TRPC6 and phosphorylated-calcium/calmodulin-dependent protein kinase II when compared with control fibroblasts. In the presence of ethylene glycol tetra-acetic acid (a free Ca²⁺ chelator, 1 mM) or U73122 (an inhibitor of phospholipase C, 1 μM), control and FGF-23-treated fibroblasts exhibited similar proliferative and migratory abilities. Moreover, polymerase chain reaction analysis revealed that atrial fibroblasts abundantly expressed FGF receptor 1 but lacked expressions of FGF receptors 2-4. FGF-23 significantly increased the phosphorylation of FGF receptor 1. Treatment with PD166866 (an antagonist of FGF receptor 1, 1 μM) attenuated the effects of FGF-23 on cardiac fibroblast activity. In conclusion, FGF-23 may activate FGF receptor 1 and subsequently phospholipase C/IP₃ signaling pathway, leading to an upregulation of Orai1 and/or TRPC1-mediated Ca²⁺ entry and thus enhancing human atrial fibroblast activity.

Vascular endothelial growth factor modulates pulmonary vein arrhythmogenesis via vascular endothelial growth factor receptor 1/NOS pathway

Atrial fibrillation (AF) is a common form of arrhythmia with serious public health impacts, but its underlying mechanisms are not yet fully understood. Vascular endothelial growth factor (VEGF) is highly expressed in the atrium of patients with AF, but whether VEGF affects AF pathogenesis remains unclear. Pulmonary veins (PVs) are important sources for the genesis of atrial tachycardia or AF. Therefore, this study assessed the effects of VEGF on PV electrophysiological properties and evaluated its underlying mechanisms. Conventional microelectrodes and whole-cell patch clamps were performed using isolated rabbit PV preparations or single isolated PV cardiomyocytes before and after VEGF or VEGF receptor (VEGFR), Akt, NOS inhibitor administration. We found that VEGF (0.1, 1, and 10 ng/mL) reduced the PV beating rate in a dose-dependent manner. Furthermore, VEGF (10 ng/mL) reduced late diastolic depolarization and diastolic tension. Isoproterenol increased PV beating and burst firing, which was attenuated by VEGF (1 ng/mL). In the presence of VEGFR-1 inhibition (ZM306416 at 10 μM) and L-NAME (100 μM), VEGF (1 ng/mL) did not alter PV spontaneous activity. In isolated PV cardiomyocytes, VEGF (1 ng/mL) decreased L-type calcium, sodium/calcium exchanger, and late sodium currents. In conclusion, we found that VEGF reduces PV arrhythmogenesis by modulating sodium/calcium homeostasis through VEGFR-1/NOS signaling pathway.

The evaluation of functional small intestinal submucosa for abdominal wall defect repair in a rat model: Potent effect of sequential release of VEGF and TGF-β1 on host integration

Ineffective vessel penetration and extracellular matrix (ECM) remodeling are responsible for the failure of porcine small intestinal submucosa (SIS)-repaired abdominal wall defects. Combined growth factors could be used as directing signals in a nature-mimicking strategy to improve this repair through mesh functionalization. In this work, vascular endothelial growth factor (VEGF) and transforming growth factor β1 (TGF-β1) were incorporated into a silk fibroin membrane via coaxial aqueous electrospinning to exploit their benefits of biological interactions. The membrane was sandwiched into the SIS bilayer as a functional mesh to repair partial-thickness defects in a rat model. Membrane characterization demonstrated that the core-shell structure ensured the independent distribution and sequential release of two regulators and protection of their bioactivities, which were confirmed by cell viability and protein expression. The mesh was further assessed to facilitate vasculature formation and collagen secretion in vitro, and exhibited better host integration than VEGF- or TGF-β1-containing mesh and developed reinforced mechanical properties compared with the VEGF-containing mesh after 28 days in vivo. Determination of the underlying biological interactions revealed that rapid VEGF release promotes angiogenesis and collagen secretion but initially potentiates the inflammatory response. Sustained TGF-β1 release at relatively low concentrations promoted VEGF for vessel permeation and maturation and steadily induced ECM remodeling under milder foreign body reactions. The functionalization of SIS improves repair by sufficient integration with timely remodeling and helps elucidate the related regulatory interactions.

Vascular endothelial growth factor on Runt-related transcript factor-2 in aortic valve cells

BACKGROUND

Calcific aortic valve disease is associated with ageing and high mortality. However, no effective pharmacological treatment has been developed. Vascular endothelial growth factor (VEGF) and its receptor are overexpressed in the calcified aortic valve tissue. However, the role of VEGF in calcific aortic valve disease pathogenesis and its underlying mechanisms remain unclear.

MATERIALS AND METHODS

Runt-related transcription factor 2 expression and calcium-related signalling were investigated in porcine valvular interstitial cells with or without human VEGF-A recombinant protein (VEGF₁₆₅ , 1-100 ng/mL) treatment and/or calmodulin-dependent kinase II (CaMKII) inhibitor (KN93, 10 µmol/L) and inositol triphosphate receptor inhibitor (2-aminoethyldiphenyl borate, 30 µmol/L) for 5 days.

RESULTS

VEGF₁₆₅ -treated cells had higher Runt-related transcription factor 2 expression and CaMKII/ adenosine 3',5'-monophosphate response element-binding protein (CREB) signalling activation than did control cells. KN93 reduced Runt-related transcription factor 2 expression and CREB phosphorylation in VEGF₁₆₅ -treated cells. The 2-aminoethyldiphenyl borate also reduced Runt-related transcription factor 2 expression in VICs treated with VEGF₁₆₅ .

CONCLUSION

VEGF upregulated Runt-related transcription factor 2 expression in VICs by activating the IP3R/CaMKII/CREB signalling pathway.

Physiological testosterone attenuates profibrotic activities of rat cardiac fibroblasts through modulation of nitric oxide and calcium homeostasis

Testosterone deficiency is associated with poor prognosis among patients with chronic heart failure (HF). Physiological testosterone improves the exercise capacity of patients with HF. In this study, we evaluated whether treatment with physiological testosterone contributes to anti-fibrogenesis by modifying calcium homeostasis in cardiac fibroblasts and we studied the underlying mechanisms. Nitric oxide (NO) analyses, calcium (Ca²⁺) fluorescence, and Western blotting were performed in primary isolated rat cardiac fibroblasts with or without (control cells) testosterone (10, 100, 1,000 nmol/L) treatment for 48 hours. Physiological testosterone (10 nmol/L) increased NO production and phosphorylation at the inhibitory site of the inositol trisphosphate (IP3) receptor, thereby reducing Ca²⁺ entry, phosphorylated Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) expression, type I and type III pro-collagen production. Non-physiological testosterone-treated fibroblasts exhibited similar NO and collagen production capabilities as compared to control (testosterone deficient) fibroblasts. These effects were blocked by co-treatment with NO inhibitor (L-NG-nitro arginine methyl ester [L-NAME], 100 μmol/L). In the presence of the IP3 receptor inhibitor (2-aminoethyl diphenylborinate [2-APB], 50 μmol/L), testosterone-deficient and physiological testosterone-treated fibroblasts exhibited similar phosphorylated CaMKII expression. When treated with 2-APB or CaMKII inhibitor (KN93, 10 μmol/L), testosterone-deficient and physiological testosterone-treated fibroblasts exhibited similar type I, and type III collagen production. In conclusion, physiological testosterone activates NO production, and attenuates the IP3 receptor/Ca²⁺ entry/CaMKII signaling pathway, thereby inhibiting the collagen production capability of cardiac fibroblasts.

Lithium Reduces Migration and Collagen Synthesis Activity in Human Cardiac Fibroblasts by Inhibiting Store-Operated Ca2+ Entry

Cardiac fibrosis plays a vital role in the pathogenesis of heart failure. Fibroblast activity is enhanced by increases in store-operated Ca²⁺ entry (SOCE) and calcium release-activated calcium channel protein 1 (Orai1) levels. Lithium regulates SOCE; however, whether therapeutic concentrations of lithium can be used to inhibit cardiac fibrogenesis is unknown. Migration and proliferation assays, Western blotting, real-time reverse-transcription polymerase chain reaction analysis, and calcium fluorescence imaging were performed in human cardiac fibroblasts treated with or without LiCl at 1.0 mM (i.e., therapeutic peak level) or 0.1 mM (i.e., therapeutic trough level) for 24 h. Results showed that LiCl (0.1 mM, but not 1.0 mM) inhibited the migration and collagen synthesis ability of cardiac fibroblasts. Additionally, thapsigargin-induced SOCE was reduced in fibroblasts treated with LiCl (0.1 mM). The expression level of Orai1 was lower in LiCl (0.1 mM)-treated fibroblasts relative to the fibroblasts without LiCl treatment. Fibroblasts treated with a combination of LiCl (0.1 mM) and 2-APB (10 μM, an Orai1 inhibitor) demonstrated similar migration and collagen synthesis abilities as those in LiCl (0.1 mM)-treated fibroblasts. Altogether, lithium at therapeutic trough levels reduced the migration and collagen synthesis abilities of human cardiac fibroblasts by inhibiting SOCE and Orai1 expression.

Molecular Targets and Pathways Contributing to the Effects of Wenxin Keli on Atrial Fibrillation Based on a Network Pharmacology Approach

BACKGROUND

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with high rates of mortality and morbidity. The traditional Chinese medicine Wenxin Keli (WXKL) can effectively improve clinical symptoms and is safe for the treatment of AF. However, the active substances in WXKL and the molecular mechanisms underlying its effects on AF remain unclear. In this study, the bioactive compounds in WXKL, as well as their molecular targets and associated pathways, were evaluated by systems pharmacology.

MATERIALS AND METHODS

Chemical constituents and potential targets of WXKL were obtained via the Traditional Chinese Medicine Systems Pharmacology (TCMSP). The TTD, DrugBank, DisGeNET, and GeneCards databases were used to collect AF-related target genes. Based on common targets related to both AF and WXKL, a protein interaction network was generated using the STRING database. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGGs) pathway enrichment analyses were performed. Network diagrams of the active component-target and protein-protein interactions (PPIs) were constructed using Cytoscape.

RESULTS

A total of 30 active ingredients in WXKL and 219 putative target genes were screened, including 83 genes identified as therapeutic targets in AF; these overlapping genes were considered candidate targets for subsequent analyses. The effect of treating AF was mainly correlated with the regulation of target proteins, such as IL-6, TNF, AKT1, VEGFA, CXCL8, TP53, CCL2, MMP9, CASP3, and NOS3. GO and KEGG analyses revealed that these targets are associated with the inflammatory response, oxidative stress reaction, immune regulation, cardiac energy metabolism, serotonergic synapse, and other pathways.

CONCLUSIONS

This study demonstrated the multicomponent, multitarget, and multichannel characteristics of WXKL, providing a basis for further studies of the mechanism underlying the beneficial effects of WXKL in AF.

Management of Atrial Fibrillation in COVID-19 Pandemic

The health crisis due to coronavirus disease 2019 (COVID-19) has shocked the world, with more than 1 million infections and casualties. COVID-19 can present from mild illness to multi-organ involvement, but especially acute respiratory distress syndrome. Cardiac injury and arrhythmias, including atrial fibrillation (AF), are not uncommon in COVID-19. COVID-19 is highly contagious, and therapy against the virus remains premature and largely unknown, which makes the management of AF patients during the pandemic particularly challenging. We describe a possible pathophysiological link between COVID-19 and AF, and therapeutic considerations for AF patients during this pandemic.

Molecular Basis of Atrial Fibrillation Pathophysiology and Therapy: A Translational Perspective

Atrial fibrillation (AF) is a highly prevalent arrhythmia, with substantial associated morbidity and mortality. There have been significant management advances over the past 2 decades, but the burden of the disease continues to increase and there is certainly plenty of room for improvement in treatment options. A potential key to therapeutic innovation is a better understanding of underlying fundamental mechanisms. This article reviews recent advances in understanding the molecular basis for AF, with a particular emphasis on relating these new insights to opportunities for clinical translation. We first review the evidence relating basic electrophysiological mechanisms to the characteristics of clinical AF. We then discuss the molecular control of factors leading to some of the principal determinants, including abnormalities in impulse conduction (such as tissue fibrosis and other extra-cardiomyocyte alterations, connexin dysregulation and Na+-channel dysfunction), electrical refractoriness, and impulse generation. We then consider the molecular drivers of AF progression, including a range of Ca2+-dependent intracellular processes, microRNA changes, and inflammatory signaling. The concept of key interactome-related nodal points is then evaluated, dealing with systems like those associated with CaMKII (Ca2+/calmodulin-dependent protein kinase-II), NLRP3 (NACHT, LRR, and PYD domains-containing protein-3), and transcription-factors like TBX5 and PitX2c. We conclude with a critical discussion of therapeutic implications, knowledge gaps and future directions, dealing with such aspects as drug repurposing, biologicals, multispecific drugs, the targeting of cardiomyocyte inflammatory signaling and potential considerations in intervening at the level of interactomes and gene-regulation. The area of molecular intervention for AF management presents exciting new opportunities, along with substantial challenges.

Useful applications of growth factors for cardiovascular regenerative medicine

Novel advances for cardiovascular diseases (CVDs) include regenerative approaches for fibrosis, hypertrophy, and neoangiogenesis. Studies indicate that growth factor (GF) signaling could promote heart repair since most of the evidence is derived from preclinical models. Observational studies have evaluated GF serum/plasma levels as feasible biomarkers for risk stratification of CVDs. Noteworthy, two clinical interventional published studies showed that the administration of growth factors (GFs) induced beneficial effect on left ventricular ejection fraction (LVEF), myocardial perfusion, end-systolic volume index (ESVI). To date, large scale ongoing studies are in Phase I-II and mostly focussed on intramyocardial (IM), intracoronary (IC) or intravenous (IV) administration of vascular endothelial growth factor (VEGF) and fibroblast growth factor-23 (FGF-23) which result in the most investigated GFs in the last 10 years. Future data of ongoing randomized controlled studies will be crucial in understanding whether GF-based protocols could be in a concrete way effective in the clinical setting.