VEGF Improves Skeletal Muscle Regeneration After Acute Trauma and Reconstruction of the Limb in a Rabbit Model
ABSTRACT BACKGROUND: Complicated tibial fractures with severe soft tissue trauma are challenging to treat. Frequently associated acute compartment syndrome can result in scarring of muscles with impaired function. Several studies have shown a relationship between angiogenesis and more effective muscle regeneration. Vascular endothelial growth factor (VEGF) is associated with angiogenesis but it is not clear whether it would restore muscle force, reduce scarring, and aid in muscle regeneration after acute musculoskeletal trauma. QUESTIONS/PURPOSES: Therefore, we asked whether local application of VEGF (1) restores muscle force, (2) reduces scar tissue formation, and (3) regenerates muscle tissue. METHODS: We generated acute soft tissue trauma with increased compartment pressure in 22 rabbits and shortened the limbs to simulate fracture débridement. In the test group (n = 11), a VEGF-coated collagen matrix was applied locally around the osteotomy site. After 10 days of limb shortening, gradual distraction of 0.5 mm per 12 hours was performed to restore the original length. Muscle force was measured before trauma and on every fifth day after trauma. Forty days after shortening we euthanized the animals and histologically determined the percentage of connective and muscle tissue. RESULTS: Recovery of preinjury muscle strength was greater in the VEGF group (2.4 N; 73%) when compared with the control (1.8 N; 53%) with less connective and more muscle tissue in the VEGF group. The recovery of force was related to the percentage of connective tissue versus muscle fibers. CONCLUSIONS: Local application of VEGF may improve restoration of muscle force by reducing connective tissue and increasing the relative amount of muscle fibers. CLINICAL RELEVANCE: VEGF may be useful to improve skeletal muscle repair by modulating muscle tissue regeneration and fibrosis reduction after acute trauma.
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ABSTRACT: Vitamin D is mostly recognized for its regulation of calcium homeostasis in relation to the intestine, kidney, and bone. Although clinical studies have linked vitamin D with increased muscle function and strength, little is known of its underlying molecular mechanism. We recently demonstrated that 1,25-D3 exerts a direct pro-myogenic effect on skeletal muscle cells; this has provoked our investigation of 1,25-D's effect on angiogenesis, a vital process for new capillary development and tissue repair. In this study, we examined the mechanism by which 1,25-D3 modulates key angiogenic growth factors and angiogenic inhibitors. C(2)C(12) myoblasts were incubated with 100nM 1,25-D3 or placebo for 1, 4 and 10days. At the end of the respective incubation time, total RNA was isolated for PCR arrays and for qRT-PCR. Total proteins were isolated for Western blots and proteome profiler arrays. The addition of 1,25-D3 to C(2)C(12) myoblasts increased VEGFa and FGF-1: two pro-angiogenic growth factors that promote neo-vascularization and tissue regeneration, and decreased FGF-2 and TIMP-3: two myogenic and/or angiogenic inhibitors. Our previous study demonstrated that 1,25-D3 altered IGF-I/II expression, consistent with the observed changes in VEGFa and FGF-2 expression. These results extend our previous findings and demonstrate the modulation of angiogenesis which may be an additional mechanism by which 1,25-D3 promotes myogenesis. This study supports the mechanistic rationale for assessing the administration of vitamin D and/or vitamin D analogs to treat select muscle disorders and may also provide an alternative solution for therapies that directly manipulate VEGF and FGF's to promote angiogenesis.The Journal of steroid biochemistry and molecular biology 09/2012; 133C:1-11. DOI:10.1016/j.jsbmb.2012.09.004 · 4.05 Impact Factor
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ABSTRACT: Bone marrow-derived mesenchymal stromal cells (BM-MSCs) represent the leading candidate cell in tissue engineering and regenerative medicine. These cells can be easily isolated, expanded in vitro and are capable of providing significant functional benefits after implantation in the damaged muscle tissues. Despite their plasticity, the participation of BM-MSCs to new muscle fiber formation is controversial; in fact, emerging evidence indicates that their therapeutic effects occur without signs of long-term tissue engraftment and involve the paracrine secretion of cytokines and growth factors with multiple effects on the injured tissue, including modulation of inflammation and immune reaction, positive extracellular matrix (ECM) remodeling, angiogenesis and protection from apoptosis. Recently, a new role for BM-MSCs in the stimulation of muscle progenitor cells proliferation has been demonstrated, suggesting the potential ability of these cells to influence the fate of local stem cells and augment the endogenous mechanisms of repair/regeneration in the damaged tissues.12/2012; 1(4):832-50. DOI:10.3390/cells1040832
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ABSTRACT: 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.Gene Therapy advance online publication, 30 May 2013; doi:10.1038/gt.2013.26.Gene therapy 05/2013; 20(10). DOI:10.1038/gt.2013.26 · 4.20 Impact Factor