Comparable vascular response of a new generation sirolimus eluting stents when compared to fluoropolymer everolimus eluting stents in the porcine coronary restenosis model.

BACKGROUND: Novel sirolimus eluting stents (SES) have shown non-inferior clinical outcomes when compared to everolimus eluting stents (EES), however only limited preclinical data have been published. Therefore, we evaluate vascular response of a new generation biodegradable polymer SES (BP-SES: Alex Plus, Balton) and fluoropolymer EES (EES: Xience Pro, Abbott) in the porcine coronary restenosis model. METHODS: A total of 40 stents were implanted with 120% overstretch in coronaries of 17 domestic swine: 16 BP-SES, 16 EES and 8 bare metal controls (BMS). Following 28 and 90 days, coronary angiography and optical coherence tomography (OCT) was performed, animals sacrificed and stented segments harvested for pathological evaluation. RESULTS: At 28 days neointimal thickness in OCT was lowest in the BP-SES when compared to EES and BMS (0.18 ± 0.1 vs. 0.39 ± 0.1 vs. 0.34 ± 0.2 mm, respectively; p = 0.04). There was no difference in the proportion of malapposed or uncovered struts, although protruding covered struts were more common in BP-SES (14.8 ± 10% vs. 4.1 ± 4% vs. 3.7 ± 6%; p = 0.03). In pathology, the lowest neointimal thickness was confirmed in BP-SES (p < 0.05). The inflammation score was significantly lower in BP-SES and EES when compared to BMS (0.24 ± 0.1 vs. 0.4 ± 0.1 vs. 0.77 ± 0.4; p < 0.01) whilst EES and BP-SES had higher fibrin scores than BMS (1.2 ± 0.4 vs. 1.3 ± 0.3 vs. 0.17 ± 0.2; p < 0.01). At 90 days neointimal coverage and thickness in OCT was comparable between groups and healing in histopathology was complete. CONCLUSIONS: New generation, BP-SES show similar vascular healing and biocompatibility profile with marginally higher degree of restenosis inhibition, when compared to fluoropolymer EES in the porcine coronary restenosis model.

Bioresorbable drug-eluting magnesium-alloy scaffold: design and feasibility in a porcine coronary model.

AIMS: Among three versions of bioresorbable magnesium scaffolds featuring different paclitaxel-elution kinetics, we determined the best-performing scaffold and compared it with established, paclitaxel-eluting, permanent stents TAXUS Liberté and eucaTAX. METHODS AND RESULTS: Drug-elution kinetics in magnesium scaffolds were modulated by varying the composition of their bioresorbable poly(lactide-co-glycolide) coating loaded with paclitaxel. A 50:50 ratio of lactide to glycolide, or an 85:15 ratio and either high- or low-molecular-weight polymer was applied in the "50/50", "85/15H", and "85/15L" scaffolds, respectively. Seventy-three magnesium scaffolds (25 50/50, 24 85/15H, 24 85/15L) and 36 control stents (18 TAXUS Liberté, 18 eucaTAX) were implanted in coronary arteries of 50 Yucatan mini-pigs. Angiography, histomorphometry, and histopathology data were acquired at 28, 90 and 180 days. The best-performing magnesium scaffold, 85/15H, was equivalent to TAXUS Liberté and superior to eucaTAX regarding late luminal loss, intimal area, fibrin score, and endothelialisation. Intimal inflammation score was higher in 85/15H than in the control stents at 28 days, but this effect disappeared at later time points. CONCLUSIONS: By selecting suitable paclitaxel-elution kinetics, it was feasible to develop a bioresorbable magnesium scaffold whose efficacy and healing characteristics in a porcine coronary model are comparable with those of established paclitaxel-eluting permanent metallic stents.

Comparative vascular responses three months after paclitaxel and everolimus-eluting stent implantation in streptozotocin-induced diabetic porcine coronary arteries.

BACKGROUND: Diabetes remains a significant risk factor for restenosis/thrombosis following stenting. Although vascular healing responses following drug-eluting stent (DES) treatment have been characterized previously in healthy animals, comparative assessments of different DES in a large animal model with isolated features of diabetes remains limited. We aimed to comparatively assess the vascular response to paclitaxel-eluting (PES) and everolimus-eluting (EES) stents in a porcine coronary model of streptozotocin (STZ)-induced type I diabetes. METHOD: Twelve Yucatan swine were induced hyperglycemic with a single STZ dose intravenously to ablate pancreatic ß-cells. After two months, each animal received one XIENCE V® (EES) and one Taxus Liberte (PES) stent, respectively, in each coronary artery. After three months, vascular healing was assessed by angiography and histomorphometry. Comparative in vitro effects of everolimus and paclitaxel (10-5 M-10-12 M) after 24 hours on carotid endothelial (EC) and smooth muscle (SMC) cell viability under hyperglycemic (42 mM) conditions were assayed by ELISA. Caspase-3 fluorescent assay was used to quantify caspase-3 activity of EC treated with everolimus or paclitaxel (10-5 M, 10-7 M) for 24 hours. RESULTS: After 3 months, EES reduced neointimal area (1.60 ± 0.41 mm, p < 0.001) with trends toward reduced % diameter stenosis (11.2 ± 9.8%, p = 0.12) and angiographic late-loss (0.28 ± 0.30 mm, p = 0.058) compared to PES (neointimal area: 2.74 ± 0.58 mm, % diameter stenosis: 19.3 ± 14.7%, late loss: 0.55 ± 0.53 mm). Histopathology revealed increased inflammation scores (0.54 ± 0.21 vs. 0.08 ± 0.05), greater medial necrosis grade (0.52 ± 0.26 vs. 0.0 ± 0.0), and persistently elevated fibrin scores (1.60 ± 0.60 vs. 0.63 ± 0.41) with PES compared to EES (p < 0.05). In vitro, paclitaxel significantly increased (p < 0.05) EC/SMC apoptosis/necrosis at high concentrations (≥ 10-7 M), while everolimus did not affect EC/SMC apoptosis/necrosis within the dose range tested. In ECs, paclitaxel (10-5 M) significantly increased caspase-3 activity (p < 0.05) while everolimus had no effect. CONCLUSION: After 3 months, both DES exhibited signs of delayed healing in a STZ-induced diabetic swine model. PES exhibited greater neointimal area, increased inflammation, greater medial necrosis, and persistent fibrin compared to EES. Differential effects of everolimus and paclitaxel on vascular cell viability may potentially be a factor in regulating delayed healing observed with PES. Further investigation of molecular mechanisms may aid future development of stent-based therapies in treating coronary artery disease in diabetic patients.

Use of magnetic resonance imaging and histopathologic findings for diagnosis of an aneurysmal bone cyst in the scapula of a cat.

CASE DESCRIPTION: An 18-month-old spayed female domestic shorthair cat was evaluated because of left thoracic limb lameness. CLINICAL FINDINGS: A firm mass was palpable in the left scapular region. On the basis of clinical signs; results of radiographic, ultrasonographic, and cytologic evaluations; and findings on magnetic resonance imaging, an aneurysmal bone cyst (ABC) of the scapula was strongly suspected. TREATMENT AND OUTCOME: Considering the large size of the mass and the poor prognosis for return to function of the left thoracic limb, amputation was elected. Histologic evaluation ruled out a malignant process and was diagnostic for ABC originating from the left scapula. The patient recovered well and was ambulatory the day after surgery. Three years after surgery, the cat was healthy. CLINICAL RELEVANCE: The combination of radiography, regional ultrasonography, and magnetic resonance imaging enabled lesion structure and cavity content evaluation. However, final diagnosis was confirmed by histologic evaluation. To our knowledge, this is the first veterinary report of the use of magnetic resonance imaging in the characterization and diagnosis of an ABC.

Effects of timing of dexamethasone treatment on the outcome of collagenase-induced intracerebral hematoma in rats.

The effect of timing in providing dexamethasone treatment after intracerebral hematoma was evaluated in rats with hematoma induced by a subcortical collagenase injection. Male Sprague-Dawley rats (n = 30; body weight, 185 to 230 g) received dexamethasone (1 mg/kg) intraperitoneally at 2 h, 4 h, or 6 h (1 group per time point) after intracerebral collagenase injection, with another dose (1 mg/kg) administered at 24 h after collagenase injection. Neurologic examinations and rotarod treadmill tests were used to evaluate motor behavior before and at 24 and 48 h after intracerebral injection. Rats were euthanized after the last behavioral test. Brains were evaluated for hematoma size, number of penumbral necrotic neurons, neutrophils within the hematoma, and astrocytic response. Compared with the control and other treatment groups, rats treated with dexamethasone at 2 and 24 h after intracerebral collagenase injection scored significantly better on neurologic exams and rotarod tests. Hematoma volume was significantly smaller in all treated groups than in the control group but did not differ between treatment groups. Fewer neutrophils were seen in the perihematoma region of all treated rats compared with controls, but the number of necrotic neurons was decreased significantly only in the group treated with dexamethasone at 2 and 24 h. These results indicate that a 1-mg/kg dose of dexamethasone is beneficial for treatment of intracerebral hemorrhage, particularly if administered early after the hemorrhagic insult.

Congenital branchial apparatus malformation in a Haflinger colt.

OBJECTIVE: To report the diagnosis and treatment of a branchial apparatus anomaly (BAA) associated with a mandibular malformation in a foal. DESIGN: Clinical report. ANIMAL: Haflinger foal. METHODS: A 6-day-old foal had a fluctuating cystic mass in the pharyngeal (throatlatch) region, which changed in appearance after ingestion of milk. Upper airway endoscopy and diagnostic imaging (ultrasonography, radiography, computed tomography) permitted identification of the anatomic location of a communicating tract between the lumen of the cystic mass and the pharynx. The mass was surgically removed and communication with the pharynx ligated. Histologic appearance of this mass was consistent with a branchial cyst or sinus. The mandibular malformation was managed conservatively. RESULTS: Surgical resection of a third branchial sinus resulted in an excellent functional and cosmetic outcome. There was no evidence of any mandibular deformity 2 years later. CONCLUSION: BAA may induce secondary mandibular deformation in utero and may cause respiratory compromise postpartum. Careful surgical dissection and removal of BAA resulted in an excellent outcome. CLINICAL RELEVANCE: BAAs should be included in the differential diagnosis of a throatlatch region mass in equine neonates. Complete surgical excision is recommended and full recovery of any associated mandibular deformity may be anticipated without additional treatment in very young patients.