Wound healing gene therapy: cartilage regeneration induced by vascular endothelial growth factor plasmid

Enhancement of musculocutaneous nerve reinnervation after vascular endothelial growth factor (VEGF) gene therapy

Background

Vascular endothelial growth factor (VEGF) is not only a potent angiogenic factor but it also promotes axonal outgrowth and proliferation of Schwann cells. The aim of the present study was to quantitatively assess reinnervation of musculocutaneous nerve (MCN) stumps using motor and primary sensory neurons after plasmid phVEGF transfection and end-to-end (ETE) or end-to-side (ETS) neurorrhaphy. The distal stump of rat transected MCN, was transfected with plasmid phVEGF, plasmid alone or treated with vehiculum and reinnervated following ETE or ETS neurorrhaphy for 2 months. The number of motor and dorsal root ganglia neurons reinnervating the MCN stump was estimated following their retrograde labeling with Fluoro-Ruby and Fluoro-Emerald. Reinnervation of the MCN stumps was assessed based on density, diameter and myelin sheath thickness of regenerated axons, grooming test and the wet weight index of the biceps brachii muscles.

Results

Immunohistochemical detection under the same conditions revealed increased VEGF in the Schwann cells of the MCN stumps transfected with the plasmid phVEGF, as opposed to control stumps transfected with only the plasmid or treated with vehiculum. The MCN stumps transfected with the plasmid phVEGF were reinnervated by moderately higher numbers of motor and sensory neurons after ETE neurorrhaphy compared with control stumps. However, morphometric quality of myelinated axons, grooming test and the wet weight index were significantly better in the MCN plasmid phVEGF transfected stumps. The ETS neurorrhaphy of the MCN plasmid phVEGF transfected stumps in comparison with control stumps resulted in significant elevation of motor and sensory neurons that reinnervated the MCN. Especially noteworthy was the increased numbers of neurons that sent out collateral sprouts into the MCN stumps. Similarly to ETE neurorrhaphy, phVEGF transfection resulted in significantly higher morphometric quality of myelinated axons, behavioral test and the wet weight index of the biceps brachii muscles.

Conclusion

Our results showed that plasmid phVEGF transfection of MCN stumps could induce an increase in VEGF protein in Schwann cells, which resulted in higher quality axon reinnervation after both ETE and ETS neurorrhaphy. This was also associated with a better wet weight biceps brachii muscle index and functional tests than in control rats.

Correlation of peripheral arterial blood flow with plasma chemerin and VEGF in diabetic peripheral vascular disease

Aims: Progressive vasodegeneration in microvascular beds is the major underlying factor in initiation and progression of diabetic complications. Chemerin shows a strong correlation with various facets of the metabolic syndrome, which is associated with dysregulated angiogenesis. VEGF is shown to have an angiogenic role in certain cardiovascular risk factors, including diabetes. Ankle/brachial index is a known approach for assessing lower-limb peripheral vascular disease. This study aimed to elucidate the correlation of ankle/brachial index as a marker of peripheral blood flow with biomarkers of angiogenesis, plasma chemerin and VEGF, in diabetic peripheral vascular disease. Materials & methods: Ninety age- and sex-matched females were enrolled in the study: 30 were controls, while 60 had Type 2 diabetes, of whom 30 had controlled diabetes (group II) and 30 had diabetes with peripheral vascular disease (group III) diagnosed by an abnormal ankle/brachial index. Plasma levels of chemerin and VEGF were measured. Results: There was a significant decrease of the ankle/brachial index and significant increase in plasma chemerin and VEGF in diabetic patients with peripheral vascular disease (p < 0.05). A positive correlation was observed between ankle/brachial index, plasma chemerin and VEGF in diabetic patients with peripheral vascular disease. Linear regression analysis revealed that neither chemerin nor VEGF were predictors for ankle/brachial index in diabetic peripheral vascular disease. Conclusion: This study elucidates, for the first time, the rise of plasma levels of chemerin and VEGF, and their positive correlation with ankle/brachial index in diabetic peripheral vascular disease. These findings denote their angiogenic effect of improving the peripheral blood flow in diabetic peripheral vascular disease. Further studies are warranted to examine the exact role of these two biomarkers in diabetic vasculopathy.