Angiogenic Impairment of the Vascular Endothelium

Abstract

Objective— Dystrophin, the missing or defective protein in Duchenne muscular dystrophy, is expressed not only in muscle cells but also in vascular endothelial cells (ECs). In this study, we assessed the effects of dystrophin deficiency on the angiogenic capacities of ECs. Approach and Results— We isolated vascular ECs from mdx mice, the murine equivalent of Duchenne muscular dystrophy in humans, and wild-type controls, and we found that mdx -derived ECs have impaired angiogenic properties, in terms of migration, proliferation, and tube formation. They also undergo increased apoptosis in vitro compared with wild-type cells and have increased senescence-associated β-galactosidase activity. Mdx -derived ECs also display reduced ability to support myoblast proliferation when cocultured with satellite cell–derived primary myoblasts. These endothelial defects are mirrored by systemic impairment of angiogenesis in vivo, both on induction of ischemia, stimulation with growth factors in the corneal model and matrigel plug assays, and tumor growth. We also found that dystrophin forms a complex with endothelial NO synthase and caveolin-1 in ECs, and that NO production and cGMP formation are compromised in ECs isolated from mdx mice. Interestingly, treatment with aspirin enhances production of both cGMP and NO in dystrophic ECs, whereas low-dose aspirin improves the dystrophic phenotype of mdx mice in vivo, in terms of resistance to physical exercise, muscle fiber permeability, and capillary density. Conclusions— These findings demonstrate that impaired angiogenesis is a novel player and potential therapeutic target in Duchenne muscular dystrophy.

Pharmacological Inhibition of PKCθ Counteracts Muscle Disease in a Mouse Model of Duchenne Muscular Dystrophy

“…Since reduced capillarity in muscles from mdx mice was previously described as a result of necrosis-induced muscle ischemia (Palladino et al, 2013), we then counted the number of capillaries in GA muscles from C20-treated and untreated mdx mice. In line with the observation of boosted regeneration, the number of capillaries was higher in muscle derived from C20-treated than in muscle derived from vehicle-treated mdx mice, and was similar to that counted in GA muscles from age-matched WT mice (Fig.…”

Angiogenesis as a novel therapeutic strategy for Duchenne muscular dystrophy through decreased ischemia and increased satellite cells

“…Another report shows that angiogenesis is impaired in mdx mice, not only in muscle, but systemically, which was proven by laser Doppler perfusion imaging in the hind limb ischemic model, VEGF induced neovascularization quantification in the corneal model, Matrigel subcutaneous angiogenic assay, and quantification of tumor growth and vascularization in the tumor implant model (Palladino et al, 2013). …”

“…Studies of blood perfusion in mdx mice indicate age or disease progression may have a major effect in vascular changes. A study with 2-month-old mdx mice showed increased blood flow compared to the wild type control in the hindlimb ischemia model, whereas older mice of 6 months showed decreased blood flow (Straino et al, 2004; Palladino et al, 2013). In wild type mice, it has been indicated that aged mice have a reduced response to angiogenesis after ischemia (Palladino et al, 2011, 2012).…”

Functional muscle ischemia in Duchenne and Becker muscular dystrophy

“…Also unknown is if functional ischemia manifests primarily as maldistribution of blood flow within the active muscles or as reduced total muscle blood flow. Compensatory mechanisms such as angiogenesis that are engaged to counteract muscle ischemia appear to be robust in young mdx mice (Straino et al, 2004), but impaired in older mdx mice (Palladino et al, 2013), suggesting that the impact of muscle ischemia on disease progression may vary over time.…”