Prolonging the therapeutic window for valproic acid treatment in a swine model of traumatic brain injury and hemorrhagic shock.

BACKGROUND: It has previously been shown that administration of valproic acid (VPA) can improve outcomes if given within an hour following traumatic brain injury (TBI). This short therapeutic window (TW) limits its use in real-life situations. Based upon its pharmacokinetic data, we hypothesized that TW can be extended to 3 hours if a second dose of VPA is given 8 hours after the initial dose. METHOD: Yorkshire swine (40-45 kg; n = 10) were subjected to TBI (controlled cortical impact) and 40% blood volume hemorrhage. After 2 hours of shock, they were randomized to either (1) normal saline resuscitation (control) or (2) normal saline-VPA (150 mg/kg × two doses). First dose of VPA was started 3 hours after the TBI, with a second dose 8 hours after the first dose. Neurologic severity scores (range, 0-36) were assessed daily for 14 days, and brain lesion size was measured via magnetic resonance imaging on postinjury day 3. RESULTS: Hemodynamic and laboratory parameters of shock were similar in both groups. Valproic acid-treated animals had significantly less neurologic impairment on days 2 (16.3 ± 2.0 vs. 7.3 ± 2.8) and 3 (10.9 ± 3.6 vs. 2.8 ± 1.1) postinjury and returned to baseline levels 54% faster. Magnetic resonance imaging showed no differences in brain lesion size on day 3. Pharmacokinetic data confirmed neuroprotective levels of VPA in the circulation. CONCLUSION: This is the first study to demonstrate that VPA can be neuroprotective even when given 3 hours after TBI. This expanded TW has significant implications for the design of the clinical trial.

Recombinant human MG53 protein attenuates brain lesion size in a large animal model of traumatic brain injury.

BACKGROUND: MG53, a member of the tripartite motif (TRIM) protein family, plays an essential role in cell membrane repair and promotes cell survival. Recent studies show that systemic delivery of recombinant human MG53 (rhMG53) protein markedly attenuates tissue injury/inflammation, and facilitates healing. This study was performed to test whether intravenous administration of rhMG53 protein would decrease the lesion size in a clinically relevant large animal model of traumatic brain injury (TBI). METHOD: Yorkshire swine (40-45 kg; n = 5/group) were subjected to controlled cortical impact TBI and randomized to either: (1) rhMG53 protein (2 mg/kg, intravenous) or (2) normal saline control. Hemodynamics, intracranial pressure, and brain oxygenation were monitored for 7 hours. Brains were then harvested and sectioned into 5-mm slices and stained with 2,3,5-triphenyltetrazolium chloride to quantify the lesion size. Blood-brain barrier permeability of MG53 in the brain was determined by Western blot and immunohistochemistry. Bcl-2 and phospho-GSK ß levels were measured as makers of prosurvival pathway activation. RESULTS: Hemodynamic parameters were similar in both groups, but the lesion size in the rhMG53-treated group (2,517 ± 525.4 mm 3 ) was significantly ( p < 0.05) smaller than the control group (3,646 ± 740.1 mm 3 ). In the treated animals, rhMG53 was detected in the regions surrounding the TBI, but it was absent in the saline-treated control animals. Bcl-2 and phospho-GSK ß levels in the brains were upregulated in the rhMG53-treated animals. CONCLUSION: Intravenously administered rhMG53 localizes to the injured areas of the brain, with the treated animals demonstrating a significant attenuation in the brain lesion size following TBI.

Novel Receptor for Advanced Glycation End Products-Blocking Antibody to Treat Diabetic Peripheral Artery Disease.

Background Expression of receptor for advanced glycation end products (RAGE) plays an important role in diabetic peripheral artery disease. We proposed to show that treatment with an antibody blocking RAGE would improve hind limb perfusion and muscle viability in diabetic pig with femoral artery (FA) ligation. Methods and Results Purpose-bred diabetic Yucatan minipigs with average fasting blood sugar of 357 mg/dL on insulin to maintain a glucose range of 300 to 500 mg/dL were treated with either a humanized monoclonal anti-RAGE antibody (CR-3) or nonimmune IgG. All pigs underwent intravascular occlusion of the anterior FA. Animals underwent (201Tl) single-photon emission computed tomography/x-ray computed tomography imaging on days 1 and 28 after FA occlusion, angiogenesis imaging with [99mTc]dodecane tetra-acetic acid-polyethylene glycol-single chain vascular endothelial growth factor (scVEGF), muscle biopsies on day 7, and contrast angiogram day 28. Results showed greater increases in perfusion to the gastrocnemius from day 1 to day 28 in CR-3 compared with IgG treated pigs (P=0.0024), greater uptake of [99mTc]dodecane tetra-acetic acid-polyethylene glycol-scVEGF (scV/Tc) in the proximal gastrocnemius at day 7, confirmed by tissue staining for capillaries and vascular endothelial growth factor A, and less muscle loss and fibrosis at day 28. Contrast angiograms showed better reconstitution of the distal FA from collaterals in the CR-3 versus IgG treated diabetic pigs (P=0.01). The gastrocnemius on nonoccluded limb at necropsy had higher 201Tl uptake (percentage injected dose per gram) and reduced RAGE staining in arterioles in CR-3 treated compared with IgG treated animals (P=0.04). Conclusions A novel RAGE-blocking antibody improved hind limb perfusion and angiogenesis in diabetic pigs with FA occlusion. Contributing factors are increased collaterals and reduced vascular RAGE expression. CR-3 shows promise for clinical treatment in diabetic peripheral artery disease.