Inhibition of FLT1 ameliorates muscular dystrophy phenotype by increased vasculature in a mouse model of Duchenne muscular dystrophy

Abstract

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disease in which the dystrophin coding for a membrane stabilizing protein is mutated. Recently, the vasculature has also shown to be perturbed in DMD and DMD model mdx mice. Recent DMD transcriptomics revealed the defects were correlated to a vascular endothelial growth factor (VEGF) signaling pathway. To reveal the relationship between DMD and VEGF signaling, mdx mice were crossed with constitutive (CAGCreERTM:Flt1LoxP/LoxP) and endothelial cell-specific conditional gene knockout mice (Cdh5CreERT2:Flt1LoxP/LoxP) for Flt1 (VEGFR1) which is a decoy receptor for VEGF. Here, we showed that while constitutive deletion of Flt1 is detrimental to the skeletal muscle function, endothelial cell-specific Flt1 deletion resulted in increased vascular density, increased satellite cell number and improvement in the DMD-associated phenotype in the mdx mice. These decreases in pathology, including improved muscle histology and function, were recapitulated in mdx mice given anti-FLT1 peptides or monoclonal antibodies, which blocked VEGF-FLT1 binding. The histological and functional improvement of dystrophic muscle by FLT1 blockade provides a novel pharmacological strategy for the potential treatment of DMD.

Age-Dependent Dysregulation of Muscle Vasculature and Blood Flow Recovery after Hindlimb Ischemia in the mdx Model of Duchenne Muscular Dystrophy

“…Though dysregulation of angiogenesis was proposed to contribute to DMD pathology already in the pre-dystrophin era [ 11 ], and vascular-based approaches showed a promise in preclinical animal studies [ 21 , 46 , 47 , 48 ], no clear consensus about the angiogenesis status in mdx mice exists to date. A detailed description of the vascular changes associated with the age of mdx animals, along with the verification of published data, might help in planning studies that investigate the therapeutic potential of vascular therapies utilizing this most commonly used mouse model of DMD.…”

VEGFR-1/Flt-1 inhibition increases angiogenesis and improves muscle function in a mouse model of Duchenne muscular dystrophy

“…Indeed, increased vascularization and muscle strength have been observed in mdx mice to correlate with both developmental and conditional Flt-1 deficiency. 19 , 20 …”

“… 33 In addition, commercially available mouse antibodies were found to have low affinity for sFlt-1. 20 As an alternative, we used a phage display approach to identify an anti-Flt-1 mAb with longer exposure and engineered it for high target specificity and affinity. Furthermore, we formatted the Fc regions of the mAbs for use in different species during development.…”

“… 5 Indeed, loss of Flt-1 has been shown to improve angiogenesis and ameliorate muscle weakness in mdx mice, which lack dystrophin and are widely used as a model of DMD. 19 , 20 Although the DMD phenotype in mdx mice is less severe than in humans, the mice show muscle degeneration, decreased vasculature, extensive fibrosis, and other key characteristics of the disease. 21 …”

Donnan dominated ion homeostasis and the longevity of ischemic Na+-loaded dystrophic skeletal muscle

“…Dystrophic muscle fibers, ischemia and blebdamaged sarcolemma A. SMF ischemia in DMD has several distinct causes 1. Vascular insufficiency (Verma et al 2019;Podkalicka et al 2019).…”