Effect of vascular endothelial growth factor gene therapy on post-traumatic peripheral nerve regeneration and denervation-related muscle atrophy

Functional recovery after peripheral nerve injury depends on both improvement of nerve regeneration and prevention of denervation-related skeletal muscle atrophy. To reach these goals, in this study we overexpressed vascular endothelial growth factor (VEGF) by means of local gene transfer with adeno-associated virus (AAV). Local gene transfer in the regenerating peripheral nerve was obtained by reconstructing a 1-cm-long rat median nerve defect using a vein segment filled with skeletal muscle fibers that have been previously injected with either AAV2-VEGF or AAV2-LacZ, and the morphofunctional outcome of nerve regeneration was assessed 3 months after surgery. Surprisingly, results showed that overexpression of VEGF in the muscle-vein-combined guide led to a worse nerve regeneration in comparison with AAV-LacZ controls. Local gene transfer in the denervated muscle was obtained by direct injection of either AAV2-VEGF or AAV2-LacZ in the flexor digitorum sublimis muscle after median nerve transection and results showed a significantly lower progression of muscle atrophy in AAV2-VEGF-treated muscles in comparison with muscles treated with AAV2-LacZ. Altogether, our results suggest that local delivery of VEGF by AAV2-VEGF-injected transplanted muscle fibers do not represent a rational approach to promote axonal regeneration along a venous nerve guide. By contrast, AAV2-VEGF direct local injection in denervated skeletal muscle significantly attenuates denervation-related atrophy, thus representing a promising strategy for improving the outcome of post-traumatic neuromuscular recovery after nerve injury and repair

Paracrine effect of regulatory T cells promotes cardiomyocyte proliferation during pregnancy and after myocardial infarction

Cardiomyocyte proliferation stops at birth when the heart is no longer exposed to maternal blood and, likewise, to regulatory T cells (Tregs) that are expanded to promote maternal tolerance towards the fetus. Here, we report a role of Tregs in promoting cardiomyocyte proliferation. Treg-conditioned medium promotes cardiomyocyte proliferation, similar to the serum from pregnant animals. Proliferative cardiomyocytes are detected in the heart of pregnant mothers, and Treg depletion during pregnancy decreases both maternal and fetal cardiomyocyte proliferation. Treg depletion after myocardial infarction results in depressed cardiac function, massive inflammation, and scarce collagen deposition. In contrast, Treg injection reduces infarct size, preserves contractility, and increases the number of proliferating cardiomyocytes. The overexpression of six factors secreted by Tregs (Cst7, Tnfsf11, Il33, Fgl2, Matn2, and Igf2) reproduces the therapeutic effect. In conclusion, Tregs promote fetal and maternal cardiomyocyte proliferation in a paracrine manner and improve the outcome of myocardial infarction

A microRNA program regulates the balance between cardiomyocyte hyperplasia and hypertrophy and stimulates cardiac regeneration

Myocardial regeneration is restricted to early postnatal life, when mammalian cardiomyocytes still retain the ability to proliferate. The molecular cues that induce cell cycle arrest of neonatal cardiomyocytes towards terminally differentiated adult heart muscle cells remain obscure. Here we report that the miR-106b~25 cluster is higher expressed in the early postnatal myocardium and decreases in expression towards adulthood, especially under conditions of overload, and orchestrates the transition of cardiomyocyte hyperplasia towards cell cycle arrest and hypertrophy by virtue of its targetome. In line, gene delivery of miR-106b~25 to the mouse heart provokes cardiomyocyte proliferation by targeting a network of negative cell cycle regulators including E2f5, Cdkn1c, Ccne1 and Wee1. Conversely, gene-targeted miR-106b~25 null mice display spontaneous hypertrophic remodeling and exaggerated remodeling to overload by derepression of the prohypertrophic transcription factors Hand2 and Mef2d. Taking advantage of the regulatory function of miR-106b~25 on cardiomyocyte hyperplasia and hypertrophy, viral gene delivery of miR-106b~25 provokes nearly complete regeneration of the adult myocardium after ischemic injury. Our data demonstrate that exploitation of conserved molecular programs can enhance the regenerative capacity of the injured heart.E.D. is supported by a VENI award 916-150-16 from the Netherlands Organization for Health Research and Development (ZonMW), an EMBO Long-term Fellowship (EMBO ALTF 848-2013) and a FP7 Marie Curie Intra-European Fellowship (Project number 627539). V.S.P. was funded by a fellowship from the FCT/ Ministério da Ciência, Tec-nologia e Inovação SFRH/BD/111799/2015. P.D.C.M. is an Established Investigator of the Dutch Heart Foundation. L.D.W. acknowledges support from the Dutch CardioVascular Alliance (ARENA-PRIME). L.D.W. was further supported by grant 311549 from the European Research Council (ERC), a VICI award 918-156-47 from the Dutch Research Council and Marie Sklodowska-Curie grant agreement no. 813716 (TRAIN-HEART)

Genetic Basis of Myocarditis: Myth or Reality?

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Inducible adeno-associated virus vectors promote functional angiogenesis in adult organisms via regulated vascular endothelial growth factor expression

AIMS: Members of the vascular endothelial growth factor (VEGF) family are among the most promising cytokines to induce neovascularization of ischaemic tissues; however, their unregulated expression often results in major undesired effects. Here, we describe the properties of inducible vectors based on the adeno-associated virus (AAV), allowing precise control of VEGF expression, and exploit these vectors to define the kinetics of the angiogenic response elicited by the factor. METHODS AND RESULTS: Based on a tetracycline-inducible transactivator, we designed an AAV vector system allowing the pharmacological regulation of VEGF production in vivo and tested its efficacy in inducing functional neoangiogenesis in both normoperfused and ischaemic skeletal muscle in mice by a combination of histological, immunofluorescent, and molecular imaging techniques. We observed that a prolonged expression of VEGF was required to determine the formation of stable vessels, able to persist upon withdrawal of the angiogenic stimulus. However, the vessels formed in the presence of continuous VEGF expression consisted mainly of dilated and leaky capillaries. As determined after pinhole scintigraphy, this abnormal vasculature accounted for a significant drop in functional tissue perfusion. In contrast, transient VEGF expression, followed by a period of VEGF withdrawal, allowed maintenance of functional perfusion under resting conditions and during exercise. This VEGF-inducible system was highly effective in improving vascularization and function in a hind-limb ischaemia model. CONCLUSION: Together, these results clearly indicate that the fine tuning of VEGF expression is required to achieve the formation of a stable vasculature able to sustain functional neovascularization

Characterization of zinc-releasing three-dimensional bioactive glass scaffolds and their effect on human adipose stem cell proliferation and osteogenic differentiation

While the addition of zinc ions to bioactive ceramics has been shown to enhance the proliferation and osteogenic differentiation of osteoblast-like cells, contradictory results have been found. Therefore, the effect of zinc-releasing ceramics on cell proliferation and differentiation into osteogenic lineages requires further clarification. The aim of this study was to evaluate the effects of zinc addition on the degradation profile of three-dimensional bioactive glass scaffold, and on the proliferation and osteogenesis of human adipose stem cells (hASCs) in these scaffolds. Bioactive glass scaffolds containing Na2O, K2O, MgO, CaO, B2O3, TiO2, P2O5 and SiO2 were prepared. The degradation was evaluated by weight loss measurement, scanning electron microscopy and elemental analysis. The degradation profile of bioactive glass was shown to slow down with the addition of zinc. Qualitative live/dead staining showed that zinc addition to bioactive glass inhibits cell spreading and proliferati

Idiopathic dilated cardiomyopathy and persistent viral infection: Lack of association in a controlled study using a quantitative assay.

BACKGROUND: It remains unclear whether idiopathic dilated cardiomyopathy (DCM) might ensue as the consequence of viral myocarditis, due to viral persistence in cardiomyocytes. To address this issue, we quantified the levels of enterovirus, Epstein-Barr virus (EBV), Herpes Simplex Virus-1 (HSV-1), Herpes Simplex Virus-2 (HSV-2), adenovirus and parvovirus B19 genomes in endomyocardial biopsies (EMBs) from patients with DCM, active myocarditis and controls. METHODS: Real-time polymerase chain reaction (PCR)-based methods using TaqMan probes were developed for the quantitative detection of viral genomes in EMBs from 35 patients with DCM and 17 with active myocarditis. A control group included 20 surgical patients with valve or coronary artery disease. RESULTS: None of the 72 samples tested positive for enteroviruses, EBV, HSV-1 or -2. One DCM patient tested positive for adenovirus. Of notice, 20/52 (38%) of patients with cardiomyopathy and 8/20 (40%) of controls were positive for parvovirus B19; no significant differences in viral titre were detected between groups. CONCLUSIONS: Our preliminary results disfavour the hypothesis that persistent myocardial viral infection might be a frequent cause of DCM. The detection of parvovirus B19 from both cardiomyopathy and non-cardiomyopathy patients supports the notion that this virus is widely spread in the populatio

A novel animal model to study non-spontaneous bisphosphonates osteonecrosis of jaw.

The aim of this study was to evaluate a novel animal model of bisphosphonates-associated osteonecrosis, which realistically recapitulates the same pathological human condition. Five Wistar rats were given intravenous zoledronic acid 0.04 mgonce a week for 5 weeks. After 2 weeks, the animals underwent the extraction of an upper molar, producing a 4 mm-diameter bone defect on the same site. After 7 weeks from the extraction, the animals were clinically examined and a bone scintigraphy was carried out. After an additional week, the rats were killed and both Computerized Tomography and histological analysis were performed. Five rats, not treated with zoledronic acid and exposed to the same surgical treatment, were used as controls. At 7 weeks after the extraction, all the rats treated with zoledronic acid showed expansion of the defect and bone exposure. These features were confirmed by bone scintigraphy. The rats of the control group demonstrated epithelialization of the bone defect and a normal uptake of the contrast medium during the scan. The Computerized Tomography scan disclosed irregularity of the cortical margin and bone destruction, which were not evident in the control group. On microscopy, the samples showed necrotic bone, loss of osteocytes and peripheral resorption without inflammatory infiltrate, while the controls showed normal bone healing. The rat treated with zoledronic acid can be considered a novel, reliable and reproducible animal model to understand better the pathophysiology of osteonecrosis of the jaw and to develop a therapeutic approach