VEGF over-expression in skeletal muscle induces angiogenesis by intussusception rather than sprouting

Therapeutic over-expression of vascular endothelial growth factor (VEGF) can be used to treat ischemic conditions. However, VEGF can induce either normal or aberrant angiogenesis depending on its dose in the microenvironment around each producing cell in vivo, which limits its clinical usefulness. The goal herein was to determine the cellular mechanisms by which physiologic and aberrant vessels are induced by over-expression of different VEGF doses in adult skeletal muscle. We took advantage of a well-characterized cell-based platform for controlled gene expression in skeletal muscle. Clonal populations of retrovirally transduced myoblasts were implanted in limb muscles of immunodeficient mice to homogeneously over-express two specific VEGF164 levels, previously shown to induce physiologic and therapeutic or aberrant angiogenesis, respectively. Three independent and complementary methods (confocal microscopy, vascular casting and 3D-reconstruction of serial semi-thin sections) showed that, at both VEGF doses, angiogenesis took place without sprouting, but rather by intussusception, or vascular splitting. VEGF-induced endothelial proliferation without tip-cell formation caused an initial homogeneous enlargement of pre-existing microvessels, followed by the formation of intravascular transluminal pillars, hallmarks of intussusception. This was associated with increased flow and shear stress, which are potent triggers of intussusception. A similar process of enlargement without sprouting, followed by intussusception, was also induced by VEGF over-expression through a clinically relevant adenoviral gene therapy vector, without the use of transduced cells. Our findings indicate that VEGF over-expression, at doses that have been shown to induce functional benefit, induces vascular growth in skeletal muscle by intussusception rather than sproutin

Double-plate compound osteosynthesis for pathological fractures of the proximal femur: high survivorship and low complication rate.

INTRODUCTION Management of pathological fractures of the proximal femur is often challenging. Compound double-plate osteosynthesis has been specifically developed for surgical treatment of these pathological fractures. To our knowledge, this study represents the largest series to date of double-plate compound osteosynthesis with the longest follow-up. MATERIALS AND METHODS Using our institutional digital database, we identified 61 procedures in 53 patients at the proximal femur. Patients were divided into two groups. A 'primary' group with all cases in which a double-plate compound osteosynthesis was performed as initial procedure (n = 46) and a 'revision' group with all cases in which a double-plate compound osteosynthesis was performed as revision procedure after failed previous attempts of internal fixation (n = 15). (1) The survivorship of the hip was calculated using the Kaplan-Meier survivorship analysis. (2) Complications were graded using Sink's classification. (3) The functional outcome was quantified with the Merle d'Aubigné and Postel score. (4) Risk factors were identified based on a multivariate Cox-regression analysis. RESULTS The cumulative Kaplan-Meier survivorship of the primary group was 96% at 6 months, 90% at 1 year, 5 years and thereafter and 83% at 6 months, 74% at 1 year, 53% at 2 years for the 'revision' group (p = 0.0008). According to the classification of Sink et al., the rate of grade III and IV complications was significantly lower in the primary group (p < 0.0001). The mean Merle d'Aubigné score was 14 ± 7 at 0-3 months, 13 ± 3 at 3-6 months, 15 ± 3 at 6-12 months and 15 ± 4 thereafter (p = 0.54). The only multivariate negative predictor was previous surgery with a hazard ratio of 9.2 (p < 0.006). CONCLUSION Double-plate compound osteosynthesis is a valuable treatment option for pathological fractures in proximal femur with good functional results

VEGF over-expression in skeletal muscle induces angiogenesis by intussusception rather than sprouting

Therapeutic over-expression of vascular endothelial growth factor (VEGF) can be used to treat ischemic conditions. However, VEGF can induce either normal or aberrant angiogenesis depending on its dose in the microenvironment around each producing cell in vivo, which limits its clinical usefulness. The goal herein was to determine the cellular mechanisms by which physiologic and aberrant vessels are induced by over-expression of different VEGF doses in adult skeletal muscle. We took advantage of a well-characterized cell-based platform for controlled gene expression in skeletal muscle. Clonal populations of retrovirally transduced myoblasts were implanted in limb muscles of immunodeficient mice to homogeneously over-express two specific VEGF(164) levels, previously shown to induce physiologic and therapeutic or aberrant angiogenesis, respectively. Three independent and complementary methods (confocal microscopy, vascular casting and 3D-reconstruction of serial semi-thin sections) showed that, at both VEGF doses, angiogenesis took place without sprouting, but rather by intussusception, or vascular splitting. VEGF-induced endothelial proliferation without tip-cell formation caused an initial homogeneous enlargement of pre-existing microvessels, followed by the formation of intravascular transluminal pillars, hallmarks of intussusception. This was associated with increased flow and shear stress, which are potent triggers of intussusception. A similar process of enlargement without sprouting, followed by intussusception, was also induced by VEGF over-expression through a clinically relevant adenoviral gene therapy vector, without the use of transduced cells. Our findings indicate that VEGF over-expression, at doses that have been shown to induce functional benefit, induces vascular growth in skeletal muscle by intussusception rather than sprouting