Effect of baseline infarct size on endovascular thrombectomy with or without intravenous alteplase in stroke patients: A subgroup analysis of a randomized trial (DIRECT-MT).

BACKGROUND AND PURPOSE: DIRECT-MT showed that endovascular thrombectomy was noninferior to thrombectomy preceded by intravenous alteplase with regard to functional outcome in patients with acute ischemic stroke. In this post hoc analysis, we examined whether infarct size modified the effect of alteplase. METHODS: All patients with baseline Alberta Stroke Program Early Computed Tomography Score (ASPECTS) grades were included. The primary outcome was the 90-day modified Rankin Scale (mRS) score. Multivariate ordinal logistic regression analysis was used to calculate the adjusted common odds ratio (OR) for better functional outcome based on the mRS for thrombectomy alone versus combination therapy. An interaction term was entered to test for an interaction with baseline ASPECTS subgroups: 0-4 versus 5-7 versus 8-10. RESULTS: Of 649 patients, 323 (49.8%) were in the thrombectomy-alone group and 326 (50.2%) in the combination-therapy group. There was no significant treatment-by-trichotomized ASPECTS interaction with alteplase prior to endovascular treatment for the primary endpoint of ordinal mRS (p-value interaction term relative to ASPECTS 8-10: ASPECTS 0-4, p = 0.386; ASPECTS 5-7, p = 0.936). Adjusted common ORs for improvement in the 90-day mRS with thrombectomy alone compared with combination therapy were 1.99 (95% confidence interval = 0.72-5.46) for ASPECTS 0-4, 1.07 (0.62-1.86) for ASPECTS 5-7, and 1.03 (0.74-1.45) for ASPECTS 8-10. There was no significant difference in the safety outcomes between the two groups. CONCLUSIONS: Baseline infarct size may not modify the effect of alteplase prior to endovascular thrombectomy with regard to favorable functional outcomes and adverse events.

The "distal-to-proximal" strategy for the treatment of posterior circulation tandem occlusions: a single-centre experience.

PURPOSE: Data on posterior circulation tandem occlusions in acute ischemic stroke are scarce: recognition may be challenging and little is known about optimal treatment strategy. We report our endovascular treatment strategy for posterior circulation tandem occlusion. METHODS: Consecutive patients with posterior circulation tandem occlusions in our centre were enrolled retrospectively. The preferred strategy was "distal-to-proximal" strategy, which means opening the distal occlusion first followed by treatment of the proximal pathology. The imaging characteristics, treatment strategy, clinical outcomes, and complications of patients with posterior circulation tandem occlusions were analyzed. RESULTS: In total, 21 patients with posterior circulation tandem occlusions were enrolled in the study, which accounted for 23.6% of patients with posterior circulation stroke in our centre. The mean age was 60 years (range 32 to 80), and median pre-procedure NIHSS score was 28 (interquartile range: 13-31). Eighteen patients (85.7%) had vertebrobasilar artery tandem occlusions and 3 (14.3%) had basilar artery to basilar artery tandem occlusions. All distal occlusions were successfully recanalized (modified TICI 2b/3). Two (9.5%) of the proximal lesions were not treated. A total of 57.1% of the patients had stents implanted on the proximal occlusions. The rate of mRS 0-3 at 3 months was 57.1% and the mortality rate was 19.0%. CONCLUSION: In patients with acute ischaemic stroke caused by posterior circulation tandem occlusions, we favor "distal-to-proximal" strategy based on the positive results in this small series. Nevertheless, a more extensive study is required to explore the optimal treatment strategy further.

Stromal cell-derived factor 1α facilitates aneurysm remodeling in elastase-induced rabbit saccular aneurysm.

AIMS: Inflammation plays a crucial role in aneurysm wall remodeling, which could lead to the rupture of intracranial aneurysms. Stromal cell-derived factor 1α (SDF-1α), a vital inflammation cytokine, is also related to aneurysm pathogenesis. However, the characteristics of SDF-1α expression and its role in aneurysm remodeling remain largely unknown. In this study, we aimed to investigate the expression dynamics of SDF-1α and its correlation with aneurysm remodeling. METHODS: Saccular aneurysms were induced by porcine pancreatic elastase in New Zealand White rabbits. Aneurysm size was measured by digital subtraction angiography. Endothelial-like cells on the aneurysm wall were assessed on postoperative days 1, 3, 7, 14, 21, and 30. SDF-1α levels in the aneurysmal wall and serum were examined at several follow-up time points. Adherent molecule expression was examined, and migration assays were performed in vitro. After SDF-1α stimulation, the mobilization of endothelial-lineage cells and its role in the reendothelialization of the aneurysm wall were investigated in a saccular aneurysm rabbit model. RESULTS: After the creation of saccular aneurysms in rabbits, the aneurysm sacs were filled with acute thrombosis within 3days, followed by a significant enlargement on day 14 and maturation on day 21. Serum SDF-1α levels increased in a bimodal fashion on day 1 and day 14, whereas SDF-1α expression in the aneurysm wall reached its maximum on day 14. VE-cadherin was up-regulated after SDF-1α stimulation and down-regulated by the SDF-1α ligand blocker AMD3100. Endothelial progenitor cell migration was enhanced by SDF-1α and blocked by AMD3100. The in vivo administration of SDF-α to rabbits with saccular aneurysms promoted endothelial-lineage cell mobilization into the peripheral blood and reendothelialization of the aneurysm wall. CONCLUSIONS: The SDF-1α expression level in the peripheral blood and local aneurysm wall correlated with the aneurysm remodeling process in rabbits with elastase-induced saccular aneurysms. We conclude that SDF-1α may facilitate aneurysm wall remodeling by up-regulating VE-cadherin expression and mobilizing endothelial-lineage cells.

Decreased levels and function of circulating endothelial progenitor cells in unruptured intracranial saccular aneurysm patients.

Circulating endothelial progenitor cells (EPCs) play a critical role in maintaining endothelial integrity and keeping vascular homeostasis. Previously, we reported that EPCs were involved in repair and remodeling of aneurismal wall. In the present study, we verified this hypothesis by investigating the proliferative ability and count of EPCs in peripheral blood of patients with unruptured intracranial aneurysms (UIAs). Twenty-four patients with UIAs (UIA group) and 24 negative controls (control group) were included in this study. Peripheral blood monocytes (PBMCs) were harvested and selectively cultured. The colony-forming ability of cultured cells was analyzed and the biological functions were examined by testing the adsorption of ulex europaeus agglutinin-1 labeled by fluorescein isothiocyanate and acetylated low-density lipoprotein internalization. The migratory and adhesive ability of cultured EPCs were assessed. In vitro cultured PBMCs were identified as EPCs by examining surface markers CD34, CD133 and vascular endothelial growth factor receptor 2 using flow cytometry. EPCs from UIA group possessed significantly decreased proliferative, migratory and adhesive capacities compared with EPCs from control group. Furthermore, EPCs count in UIA group was significantly decreased. Collectively, these results indicated that the circulating EPCs of UIA patients may be involved in intracranial aneurysm repair and remodeling.

Early diagnosis of intracranial atherosclerotic large vascular occlusion: A prediction model based on DIRECT-MT data.

Aims: This study aimed to build a prediction model to early diagnose intracranial atherosclerosis (ICAS)-related large vascular occlusion (LVO) in acute ischemic stroke patients before digital subtractive angiography. Methods: Patients enrolled in the DIRECT-MT trial (NCT03469206) were included in our secondary analysis and distributed into ICAS-LVO and non-ICAS-LVO groups. We also retrieved demographic data, medical histories, clinical characteristics, and pre-operative imaging data. Hypothesis testing was used to compare data of the two groups, and univariate logistic regression was used to identify the predictors of ICAS-LVO primarily. Then, we used multivariate logistic regression to determine the independent predictors and formulate the prediction model. Model efficacy was estimated by the area under the receiver operating characteristic (ROC) curve (AUC) and diagnostic parameters generated from internal and external validations. Results: The subgroup analysis included 45 cases in the ICAS-LVO group and 611 cases in the non-ICAS-LVO group. Variates with p < 0.1 in the comparative analysis were used as inputs in the univariate logistic regression. Next, variates with p < 0.1 in the univariate logistic regression were used as inputs in the multivariate logistic regression. The multivariate logistic regression indicated that the atrial fibrillation history, hypertension and smoking, occlusion located at the proximal M1 and M2, hyperdense artery sign, and clot burden score were related to the diagnosis of ICAS-LVO. Then, we constructed a prediction model based on multivariate logistics regression. The sensitivity and specificity of the model were 84.09 and 74.54% in internal validation and 73.11 and 71.53% in external validation. Conclusion: Our current prediction model based on clinical data of patients from the DIRECT-MT trial might be a promising tool for predicting ICAS-LVO.

Higher Baseline Cortical Score Predicts Good Outcome in Patients With Low Alberta Stroke Program Early Computed Tomography Score Treated with Endovascular Treatment.

BACKGROUND: Patients with large vessel occlusion and noncontrast computed tomography (CT) Alberta Stroke Program Early CT Score (ASPECTS) <6 may benefit from endovascular treatment (EVT). There is uncertainty about who will benefit from it. OBJECTIVE: To explore the predicting factors for good outcome in patients with ASPECTS <6 treated with EVT. METHODS: We retrospectively reviewed 60 patients with ASPECTS <6 treated with EVT in our center between March 2018 and June 2019. Patients were divided into 2 groups because of the modified Rankin Score (mRS) at 90 d: good outcome group (mRS 0-2) and poor outcome group (mRS ≥3). Baseline and procedural characteristics were collected for unilateral variate and multivariate regression analyses to explore the influent variates for good outcome. RESULTS: Good outcome (mRS 0-2) was achieved in 24 (40%) patients after EVT and mortality was 20% for 90 d. Compared with the poor outcome group, higher baseline cortical ASPECTS (c-ASPECTS), lower intracranial hemorrhage, and malignant brain edema after thrombectomy were noted in the good outcome group (all P < .01). Multivariate logistic regression showed that only baseline c-ASPECTS (≥3) was positive factor for good outcome (odds ratio = 4.29; 95% CI, 1.21-15.20; P = .024). The receiver operating characteristics curve indicated a moderate value of c-ASPECTS for predicting good outcome, with the area under receiver operating characteristics curve 0.70 (95% CI, 0.56-0.83; P = .011). CONCLUSION: Higher baseline c-ASPECTS was a predictor for good clinical outcome in patients with ASPECTS <6 treated with EVT, which could be helpful to treatment decision.

Microbial activity and biodiversity responding to contamination of metal(loid) in heterogeneous nonferrous mining and smelting areas.

The combined contamination of nonferrous metal(loid) mining and smelting areas is a global issue, in need of urgent management. To our knowledge, this is the first report of microbial activities by microcalorimetry in specific nonferrous metal(loid) tailings with oligonutrition and high contents of toxic metal(loid)s. Dynamics of bacterial diversity were also characterized. Here we show that tailings had low microbial activities (Pmax = 64.1-331 µW g-1), which were accelerated by the presence of dipotassium phosphate (Pmax = 346-856 µW g-1), as measured by microcalorimetry. Frequent detection of S- and metal-resistant related genera and differences of Thiobacillus and Acidithiobacillus abundances indicated that the tailings were in an early stage of acidification. It has been further confirmed by the presence of a weak acid environment and secondary sulfur associated minerals, such as Sb2S3, FeAsS, FeS2, and CuFeS2. During the acidification process, phosphate, metal(loid)s, and microbial activity were correlated to the bacterial communities. It is suggested that the bacterial communities have metabolic capacities with a high potential for the use in management processes of multi-contaminated nonferrous metalliferous tailings.

Bacterial diversity in typical abandoned multi-contaminated nonferrous metal(loid) tailings during natural attenuation.

Abandoned nonferrous metal(loid) tailings sites are anthropogenic, and represent unique and extreme ecological niches for microbial communities. Tailings contain elevated and toxic content of metal(loid)s that had negative effects on local human health and regional ecosystems. Microbial communities in these typical tailings undergoing natural attenuation are often very poorly examined. The diversity and inferred functions of bacterial communities were examined at seven nonferrous metal(loid) tailings sites in Guangxi (China), which were abandoned between 3 and 31 years ago. The acidity of the tailings sites rose over 31 years of site inactivity. Desulfurivibrio, which were always coupled with sulfur/sulfide oxidation to dissimilate the reduction of nitrate/nitrite, were specific in tailings with 3 years abandonment. However, genus beneficial to plant growth (Rhizobium), and iron/sulfur-oxidizing bacteria and metal(loid)-related genera (Acidiferrobacter and Acidithiobacillus) were specific within tailings abandoned for 23 years or more. The increased abundance of acid-generating iron/sulfur-oxidizing and metal(loid)-related bacteria and specific bacterial communities during the natural attenuation could provide new insights for understanding microbial ecosystem functioning in mine tailings. OTUs related to Sulfuriferula, Bacillus, Sulfurifustis, Gaiella, and Thiobacillus genera were the main contributors differentiating the bacterial communities between the different tailing sites. Multiple correlation analyses between bacterial communities and geochemical parameters indicated that pH, TOC, TN, As, Pb, and Cu were the main drivers influencing the bacterial community structures. PICRUSt functional exploration revealed that the main functions were related to DNA repair and recombination, important functions for bacterial adaptation to cope with the multi-contamination of tailings. Such information provides new insights to guide future metagenomic studies for the identification of key functions beyond metal-transformation/resistance. As well, our results offers novel outlooks for the management of bacterial communities during natural attenuation of multi-contaminated nonferrous metal(loid) tailings sites.

Stent Angioplasty for Acute Intracranial Atherosclerotic Occlusion After Failed Thrombectomy: A Single-Institution Series of 55 Patients.

INTRODUCTION: Analysis of safety and effectiveness of stent angioplasty for failure of thrombectomy in patients with acute intracranial atherosclerotic occlusion. METHODS: Retrospective continuous analysis of the clinical data of 458 patients with acute stroke undergoing endovascular artery thrombectomy in Changhai Hospital of Second Military Medical University from May 2013 to February 2018. Patients with acute intracranial atherosclerotic occlusion treating with stent implantation were included and the safety and effectiveness of stent angioplasty was evaluated. RESULTS: There was successful stent release in 55 patients. There were 36 cases (65.5%) with occlusion located in the anterior circulation and 19 cases (34.5%) in the posterior circulation. Twenty patients underwent intravenous thrombolysis before surgery, and the time of admission to intravenous thrombolysis was (39.9 ± 13.2) minutes. Fifty-four patients (98.2%) achieved modified thrombolysis in cerebral infarction 2b-3 recanalization. The National Institutes of Health Stroke Scale score 2.0 (0.0,6.0) 7 days after surgery was significantly improved compared with the preoperative National Institutes of Health Stroke Scale score 12.5 (6.0-20.0) (Z = -4.073, P < 0.05). Intracranial hemorrhage occurred in 7 patients (12.7%) after surgery, among them, symptomatic intracranial hemorrhage occurred in 2 cases (3.6%). CTP examination of the skull 3-5 days after operation showed: Among 39 cases (70.9%): 33 cases (84.6%) were patency, 4 cases (10.3%) were occlusion, 2 cases (5.1%) were moderate stenosis, and 16 cases (29.1%) were not examined by computed tomography perfusion. Ninety-day follow-up showed that a total of 43 cases were followed up, and 12 cases were lost to follow-up. Thirty-four patients (79.1%) had a good prognosis 90 days after surgery (modified Rankin scale score 0-2) and 9 patients died (20.9%). CONCLUSION: When thrombectomy in patients with acute intracranial atherosclerotic occlusion fails, stent angioplasty is safe and effective; however, short-term stent reocclusion after surgery cannot be ignored. Because of the small sample size, larger multicenter clinical studies are needed to confirm this result.

China's most typical nonferrous organic-metal facilities own specific microbial communities.

The diversity and function of microorganisms have yet to be explored at non-ferrous metal mining facilities (NMMFs), which are the world's largest and potentially most toxic sources of co-existing metal(loid)s and flotation reagents (FRs). The diversity and inferred functions of different bacterial communities inhabiting two types of sites (active and abandoned) in Guangxi province (China) were investigated for the first time. Here we show that the structure and diversity of bacteria correlated with the types of mine sites, metal(loid)s, and FRs concentrations; and best correlated with the combination of pH, Cu, Pb, and Mn. Combined microbial coenobium may play a pivotal role in NMMFs microbial life. Arenimonas, specific in active mine sites and an acidophilic bacterium, carries functions able to cope with the extreme conditions, whereas Latescibacteria specific in abandoned sites can degrade organics. Such a bacterial consortium provides new insights to develop cost-effective remediation strategies of co-contaminated sites that currently remain intractable for bioremediation.

Spinal Arteriovenous Malformation Associated with Parkes Weber Syndrome: Report of Two Cases and Literature Review.

OBJECTIVE: To present 2 cases of Parkes Weber syndrome (PWS) with spinal arteriovenous malformation (AVM) and discuss the radiologic features and clinical treatment with literature review. METHODS: Clinical data on 2 patients with PWS with spinal AVM was acquired in a prospective follow-up investigation. Clinical manifestations, radiographic features, procedural results, and follow-up outcome were collected and reviewed together with a literature review. RESULTS: The first patient presented with limb weakness and urinary dysfunction and the second with repetitive subarachnoid hemorrhage followed by paraplegia. Limb hypertrophy, skin ulceration, and extensive microfistulas in the affected limb were observed in both patients. Spinal AVM was confirmed by digital subtraction angiography and endovascular embolization was performed. The first patient experienced limb amputation at 6-year follow-up as a result of chronic ulceration and the second did not have neurologic improvement. After literature review, 15 cases (male/female ratio, 5:10; mean age, 22±10.4 years) were included. The presentations comprised subarachnoid hemorrhage in 6, radicular pain in 5, myelopathy in 4, and asymptomatic in 1. Embolization was performed in 9 cases, solitary surgery in 2, and combined therapy in 4. Among 10 cases with known follow-up results, 6 achieved neurologic recovery after surgery and 1 died after solitary surgery. CONCLUSIONS: Awareness of the association between spinal AVM and PWS is essential for radiographic screening of spinal lesions with myelopathy or intracranial subarachnoid hemorrhage. Clinical therapeutic strategy should be multidisciplinary and individualized on the basis of vasculature and lesion behavior.

Effect of Baseline Characteristics on the Outcome of Stent Retriever-Based Thrombectomy in Acute Basilar Artery Occlusions: A Single-Center Experience and Pooled Data Analysis.

OBJECTIVES: To explore the association of baseline characteristics and the outcome of patients with acute basilar artery occlusion (BAO) after stent retriever-based thrombectomy (SRT). METHODS: Clinical and imaging information of consecutive SRT-treated patients with BAO from a comprehensive stroke center and up-to-date literature were reviewed respectively. The impact of baseline variables toward favorable outcome was evaluated using subgroup analysis and odds ratio (OR) extracted from published data together with single-center records using pooled analysis. RESULTS: Nineteen cases from our center and 15 published studies involving 487 cases were included. Estimated pooled favorable outcome rate was 0.3746 (95% confidence interval [CI], 0.3165-0.4327), mortality was 0.2950 (95% CI, 0.2390-0.3510). Pooled estimates showed that successful reperfusion (modified thrombolysis in cerebral ischemia scale 2b or 3) gained by SRT alone was 0.7317 (95% CI, 0.6532-0.8102) and final successful reperfusion rate with or without additional reperfusion procedures was 0.8834 (95% CI, 0.8279-0.9390). Univariate analysis indicated that patients with successful reperfusion (OR, 2.05; P = 0.05), distal segment occlusion (OR, 2.03; P = 0.03), and cardioembolus origin (OR, 2.13; P = 0.01) were more likely to have favorable outcome (modified Rankin Scale score ≤2 at 3 months). Study series that applied intra-arterial thrombolysis, angioplasty, or stenting as rescuing therapy had higher successful reperfusion rate but they did not show a higher rate of favorable outcome. CONCLUSIONS: SRT with or without additional treatment appeared to be effective for the treatment of BAO. Successful reperfusion, distal segment occlusion, and cardiac embolism were associated with favorable outcome. The overall benefit of lesions requiring additional reperfusion therapy was unclear.

A novel proximal end stenting technique for assisting embolization of a complex true posterior communicating aneurysm.

Stent-assisted coiling has been widely used for endovascular treatment in recent years with satisfying clinical outcomes. The implantation of a stent using the regular approach, however, may not be safe or effective for certain aneurysms with complex structures. In this study, we report a novel stenting technique utilizing the proximal end of the stent for assisting embolization of a wide-neck irregular true posterior communicating aneurysm. This new method is a potential treatment strategy for wide-neck aneurysms located at the origin of a tortuous and thin vessel.

Using DynaCT rotational angiography for angioarchitecture evaluation and complication detection in spinal vascular diseases.

OBJECTIVE: Preoperative comprehension of the complex angioarchitecture and intraoperative complication detection are essential in endovascular treatment and surgical planning for spinal vascular diseases. We aimed to illustrate the application of DynaCT rotational angiography for the treatment of such diseases. METHODS: We retrospectively analyzed the medical records of 23 patients with spinal vascular disease who underwent DynaCT and three-dimensional (3D) rotational angiography between January 2012 and December 2013. Diseases included spinal arteriovenous malformation, spinal dural arteriovenous fistula, and hypervascular neoplasm. Radiological post-processing images and procedural complications were reviewed to compare the advantage of rotational angiography and digital subtraction angiography (DSA). RESULTS: Rotational angiography more clearly revealed the complex angioarchitecture in cases of spinal vascular diseases based on coronal, sagittal, and transverse views compared with DSA. Subarachnoid hemorrhage was confirmed with DynaCT in one patient with spinal arteriovenous malformation, which was not shown on DSA. Both two-dimensional and 3D angiograms effectively identified the fistulous points in five cases of spinal dural arteriovenous fistula while rotational angiography vividly demonstrated the relationship of the fistulous point with the osseous structures in dual-volume mode. Tumor feeders were clearly delineated in 3D reconstructed images and easily cauterized in patients with hemangioblastoma. CONCLUSIONS: Rotational angiography clarified the relationship between the vasculature and surrounding osseous structures for surgical or endovascular therapy of spinal vascular diseases. DynaCT can detect intraoperative subarachnoid hemorrhage in a timely manner during endovascular treatment of spinal vascular diseases.

Cardiomyocyte differentiation induced in cardiac progenitor cells by cardiac fibroblast-conditioned medium.

Our previous study showed that after being treated with 5-azacytidine, Nkx2.5(+) human cardiac progenitor cells (CPCs) derived from embryonic heart tubes could differentiate into cardiomyocytes. Although 5-azacytidine is a classical agent that induces myogenic differentiation in various types of cells, the drug is toxic and unspecific for myogenic differentiation. To investigate the possibility of inducing CPCs to differentiate into cardiomyocytes by a specific and non-toxic method, CPCs of passage 15 and mesenchymal stem cells (MSCs) were treated with cardiac ventricular fibroblast-conditioned medium (CVF-conditioned medium). Following this treatment, the Nkx2.5(+) CPCs underwent cardiomyogenic differentiation. Phase-contrast microscopy showed that the morphology of the treated CPCs gradually changed. Ultrastructural observation confirmed that the cells contained typical sarcomeres. The expression of cardiomyocyte-associated genes, such as alpha-cardiac actin, cardiac troponin T, and beta-myosin heavy chain (MHC), was increased in the CPCs that had undergone cardiomyogenic differentiation compared with untreated cells. In contrast, the MSCs did not exhibit changes in morphology or molecular expression after being treated with CVF-conditioned medium. The results indicated that Nkx2.5(+) CPCs treated with CVF-conditioned medium were capable of differentiating into a cardiac phenotype, whereas treated MSCs did not appear to undergo cardiomyogenic differentiation. Subsequently, following the addition of Dkk1 and the blocking of Wnt signaling pathway, CVF-conditioned medium-induced morphological changes and expression of cardiomyocyte-associated genes of Nkx2.5(+) CPCs were inhibited, which indicates that CVF-conditioned medium-induced cardiomyogenic differentiation of Nkx2.5(+) CPCs is associated with Wnt signaling pathway. In addition, we also found that the activation of Wnt signaling pathway was accompanied by higher expression of GATA-4 and the blocking of the pathway inhibited the expression of GATA-4 in CVF-conditioned medium-incubated Nkx2.5(+) CPCs. This finding suggests that Wnt signaling pathway may alter GATA-4 expression and activate the cardiogenic program in the regulation of differentiation. In conclusion, Nkx2.5(+) CPCs have enormous potential for cardiomyogenic differentiation and the CVF-conditioned medium specifically induces CPCs to differentiate into a cardiac phenotype. Wnt signaling pathway is involved in CVF-conditioned medium-induced cardiomyogenic differentiation of Nkx2.5(+) CPCs.

Endothelial progenitor cells contribute to neointima formation in rabbit elastase-induced aneurysm after flow diverter treatment.

AIMS: Endothelial progenitor cells (EPCs) are involved in vascular repair and homeostasis after vascular injuries. In this study, we aimed to explore whether bone marrow (BM)-derived EPCs contribute to neointima formation and reendothelialization in rabbit elastase-induced aneurysm after flow diverter treatment. METHODS: Elastase-induced aneurysms were created in New Zealand male rabbits. Three weeks after model creation, flow diverter was implanted to cover the induced aneurysm neck. Autologous EPCs were isolated from bone marrow, expanded ex vivo, double labeled with Hoechst 33,342 and CFSE(carboxyfluorescein diacetate succinimidyl ester), and transplanted transvenously into the rabbits. The rabbits were assigned into three groups. The first group received autologous transfusion of double-labeled EPCs from the first day after stent implantation, and the second group received transfusion from the fifteenth day. The autologous transfusion was given at a 3-day interval and continued for 2 weeks. Fluorescence-labeled cells were tracked under fluorescence microscope at the aneurysm neck and parent artery in the two groups. The third group was established as control group without EPCs transplantation. Scanning electron microscope was used to investigate the reendothelialization rate between the former two groups and the control group. RESULTS: In the first group, double-positive EPCs were found in 3/5 rabbits and mainly located in the subendothelial space and around the stent struts. In the second group, double-positive EPCs were found in 2/5 rabbits and mainly located on the surface of neointima. More endothelial-like cells were observed on the neointima of aneurysm neck and stented parent artery in the groups with EPCs transplantation than control group without EPCs transplantation, but the difference on the number of these cells did not reach statistical significance. CONCLUSIONS: BM-derived EPCs participate in neointima formation and reendothelialization in elastase-induced aneurysm after flow diverter treatment. The EPCs may differentiate into different cell types according to the stages of neointima formation in vivo.

Development of negligible depletion hollow fiber membrane-protected liquid-phase microextraction for simultaneous determination of partitioning coefficients and acid dissociation constants.

A new method based on negligible depletion hollow fiber-protected liquid-phase microextraction coupled with high-performance liquid chromatography (HPLC) was developed for the simultaneous determination of partitioning coefficients (K(OW)) and acid dissociation constants (pK(a)), by using phenol, 4-chlorophenol and 2,4-dichlorophenol as model compounds. A 37-mm length polypropylene hollow fiber membranes (600 microm inner diameter, 200 microm wall-thickness, 0.2 microm pore size, approximately 70% porosity) with two-end sealed were filled with 1-octanol by ultrasonic agitation to prepare the extraction device. The extraction device was deployed in sample solutions, prepared by spiking target analytes in 1-octanol saturated aqueous solutions (500 mL), for negligible depletion extraction. After equilibrium was reached ( approximately 5h), the 1-octanol in the lumen of the hollow fiber membrane was collected for HPLC determination of the target analytes. As the depletion of the analytes in aqueous samples was negligible, the distribution coefficient (D(OW)) could be calculated based on the measured equilibrium concentration in 1-octanol (C(O)) and the initial concentration (C(W)) in the aqueous sample of the target analyte (D(OW)=C(O)/C(W)). The D(OW) values measured at various pH values were nonlinearly regressed with pH to obtain the K(OW) and pK(a) values of a compound. Results showed that the measured values of the K(OW) and pK(a) of these model compounds agreed well with literature data.