Qing-Quan Zu

In Vivo MR Imaging of Intraarterially Delivered Magnetically Labeled Mesenchymal Stem Cells in a Canine Stroke Model

Background This study aimed to evaluate the feasibility of intraarterial (IA) delivery and in vivo MR imaging of superparamagnetic iron oxide (SPIO)-labeled mesenchymal stem cells (MSCs) in a canine stroke model. Methodology MSCs harvested from beagles’ bone marrow were labeled with home-synthesized SPIO. Adult beagle dogs (n = 12) were subjected to left proximal middle cerebral artery (MCA) occlusion by autologous thrombus, followed by two-hour left internal carotid artery (ICA) occlusion with 5 French vertebral catheter. One week later, dogs were classified as three groups before transplantation: group A: complete MCA recanalization, group B: incomplete MCA recanalization, group C: no MCA recanalization. 3×106 labeled-MSCs were delivered through left ICA. Series in vivo MRI images were obtained before cell grafting, one and 24 hours after transplantation and weekly thereafter until four weeks. MRI findings were compared with histological studies at the time point of 24 hours and four weeks. Principal Findings Home-synthesized SPIO was useful to label MSCs without cell viability compromise. MSCs scattered widely in the left cerebral hemisphere in group A, while fewer grafted cells were observed in group B and no cell was detected in group C at one hour after transplantation. A larger infarction on the day of cell transplantation was associated with more grafted cells in the brain. Grafted MSCs could be tracked effectively by MRI within four weeks and were found in peri-infarction area by Prussian blue staining. Conclusion It is feasible of IA MSCs transplantation in a canine stroke model. Both the ipsilateral MCA condition and infarction volume before transplantation may affect the amount of grafted cells in target brain. In vivo MR imaging is useful for tracking IA delivered MSCs after SPIO labeling.

A novel embolic stroke model resembling lacunar infarction following proximal middle cerebral artery occlusion in beagle dogs.

It is estimated that lacunar infarcts account for 25% of all ischemic strokes, but its exact etiology is still on debating. The existing controversies include whether the embolisms can indeed cause lacunar stroke in humans or animal models. We hypothesized that lacunar infarction can be induced by the proximal middle cerebral artery (MCA) segmental occlusion involving the orifices of lenticulostriate arteries in animal models, which have abundant distal cerebral collateral anastomosis. Our work here establishes a proximal MCA occlusion model using thrombi (autologous blood clots about 1.7 mm in diameter and 5 mm in length) in 8 beagle dogs, evaluates the progression of ischemic lesions at 30 min interval within 6 h after embolization using the diffusion weighted imaging (DWI), and discusses the potential mechanisms of lacunar infarction. Our results indicate that the left proximal MCAs can be successfully occluded in all dogs using interventional single-thrombus method. The small solitary or multiple ischemic lesions shown in DWI were observed in the deep brain area, with the mean detecting time of 1.21 ± 0.45 h using DWI and diameter of 6.62 ± 0.60mm in 6h-DWI after procedure. In conclusion, our method established an ischemic model which can recapitulate the radiologic and histologic changes in lacunar infarcts, suggesting that emboli can cause lacunar infarcts in animal model.

Use of FLAIR Imaging to Identify Onset Time of Cerebral Ischemia in a Canine Model

After an infarction-inducing procedure, 20 dogs were imaged at 3, 4, 5, 6, and 24 hours with FLAIR and DWI. A mismatch between the 2 sequences (positive DWI and negative FLAIR) was found to reliably predict the time of infarct onset. By 6 hours, 95% of dogs had FLAIR abnormalities and by 24 hours all did. However, at 3 hours only 15% of dogs showed positive FLAIR studies. These results could serve as guidelines to estimate the time of onset of ischemic events. BACKGROUND AND PURPOSE: Stroke is a leading cause of death and disability, and many studies have focused on the evolution of FLAIR imaging in the acute and chronic time window. The purpose of this study was to evaluate the potential efficacy of FLAIR-related techniques in identifying the onset time of cerebral ischemia in a canine embolic stroke model. MATERIALS AND METHODS: An embolic ischemic model was generated through the use of an autologous clot in 20 beagle dogs. Both FLAIR and DWI were performed at 3 hours, 4 hours, 5 hours, 6 hours, and 24 hours after embolization, respectively. Visual “DWI-FLAIR mismatch” was defined as hyperintense signal detected on DWI but not on FLAIR. The relative signal intensity of FLAIR-positive lesions and the degree of DWI-FLAIR mismatch was calculated as relative FLAIR = relative signal intensity of FLAIR positive lesions, mismatch degree = (100−VFLAIR/VDWI) × 100%. RESULTS: The ischemic model was successfully established in all animals. FLAIR-positive lesions were seen in 3, 11, 16, 19, and 20 beagle dogs at 5 time points after embolization, respectively. There was significant correlation between the relative FLAIR, degree of DWI-FLAIR mismatch, and the onset time (relative FLAIR: r = +0.42; 95% CI, 0.20–0.60; mismatch degree: r = −0.85; 95% CI, 0.89–0.78). Receiver operating characteristic curves showed that the degree of DWI-FLAIR mismatch could identify the hyperacute ischemic lesions with a sensitivity range from 1.00–0.76; visual DWI-FLAIR mismatch sensitivity ranged from 0.85–0.39, whereas specificity was 0.83–0.95 versus 0.85–1.00. CONCLUSIONS: The relative FLAIR and DWI-FLAIR mismatch values were useful in predicting the onset time in our canine embolic stroke model. The degree of DWI-FLAIR mismatch proposed in our study could be a good indicator with high sensitivity for identifying the hyperacute ischemic stroke.

An endovascular canine stroke model: middle cerebral artery occlusion with autologous clots followed by ipsilateral internal carotid artery blockade

Stroke is one of the leading causes of death worldwide and the main reason for long-term disability. An appropriate animal model of stroke is urgently required for understanding the exact pathophysiological mechanism of stroke and testing any new therapeutic regimen. Our work aimed to establish a canine stroke model occluding the middle cerebral artery (MCA) and blocking the ipsilateral internal carotid artery (ICA), and to assess the infarct lesions by magnetic resonance imaging. The stroke model was generated by injecting two autologous clots into each MCA, followed by 2-h ipsilateral ICA blockade (ilICAB) using a catheter in 15 healthy adult beagles. Outcome measurements included 24-h and 7-day postocclusion T2-weighted imaging (T2WI)-based infarct volume calculation. In addition, pial collateral score, canine neurobehavioral score and histopathologic results were documented. Out of 15 dogs, 12 with successful MCA occlusion (MCAO) and ilICAB survived 7 days without complications or casualties and MCA were reperfused at 7 days after occlusion. High signal intensity in the basal ganglia and cerebral cortex on T2WI was initially observed in each dog at 6 h after the procedure. The mean percentage hemispherical infarct volume corrected for edema in all dogs on T2WI at 24 h after occlusion was 12.99±1.57%, and the degree of variability was 12.08%. The infarct volumes at 24 h after occlusion correlated with pial collateral scores and canine neurobehavioral scores well. This canine stroke model with combined MCAO and ilICAB reported here were proven to be highly feasible and reproducible.

Follow-up of 58 traumatic carotid-cavernous fistulas after endovascular detachable-balloon embolization at a single center.

Background and Purpose This study evaluated the clinical value of detachable-balloon embolization for traumatic carotid-cavernous fistula (TCCF), focusing on the frequency, risk factors, and retreatment of recurrence. Methods Fifty-eight patients with TCCF underwent transarterial detachable-balloon embolization between October 2004 and March 2011. The clinical follow-up was performed every 3 months until up to 3 years postprocedure. Each patient was placed in either the recurrence group or the nonrecurrence group according to whether a recurrence developed after the first procedure. The relevant factors including gender, fistula location, interval between trauma and the interventional procedure, blood flow in the carotid-cavernous fistula, number of balloons, and whether the internal carotid artery (ICA) was sacrificed were evaluated. Results All 58 TCCFs were successfully treated with transarterial balloon embolization, including 7 patients with ICA sacrifice. Recurrent fistulas occurred in seven patients during the follow-up period. Univariate analysis indicated that the interval between trauma and the interventional procedure (p=0.006) might be the main factor related to the recurrence of TCCF. The second treatments involved ICA sacrifice in two patients, fistula embolization with balloons in four patients, and placement of a covered stent in one patient. Conclusions Detachable balloons can still serve as the first-line treatment for TCCFs and recurrent TCCFs despite having a nonnegligible recurrence rate. Shortening the interval between trauma and the interventional procedure may reduce the risk of recurrence.

Simple quantitative measurement based on DWI to objectively judge DWI-FLAIR mismatch in a canine stroke model

PURPOSE Diffusion-weighted imaging (DWI) - fluid attenuated inversion recovery (FLAIR) mismatch was proven useful to time the onset of wake-up stroke; however, identifying the status of FLAIR imaging has been mostly subjective. We aimed to evaluate the value of relative DWI signal intensity (rDWI), and relative apparent diffusion coefficient (rADC) in identifying the FLAIR status in the acute period. METHODS Autologous clot was used to embolize left middle cerebral artery in 20 dogs. Magnetic resonance imaging was performed 3-6 hours and 24 hours after embolization. DWI-FLAIR mismatch was defined as hyperintense signal detected on DWI, but not on FLAIR. The mean values of rDWI or rADC of FLAIR- and FLAIR+ lesions were compared and the critical cutoff values of rDWI and rADC for identifying the FLAIR status were determined. RESULTS Stroke models were successfully established in all animals. DWI+ lesions were found in all 20 dogs from three hours, while FLAIR+ lesions were found in three, 11, 16, 19, and 20 dogs at five time points after embolization, respectively. The mean rDWI values were significantly different between FLAIR- and FLAIR+ lesions (P < 0.001), but rADC values were not (P = 0.73). Using rDWI=1.90 as the threshold value, excellent diagnostic efficacy was achieved (AUC, 0.88; sensitivity, 0.77; specificity, 0.88). However, rADC appeared not useful (AUC, 0.48; sensitivity, 0.52; specificity, 0.58) in identifying the FLAIR status. CONCLUSION In our embolic canine stroke model, rDWI was useful to identify FLAIR imaging status in the acute period, while rADC was not.

Chemoembolization of Recurrent Hepatoma After Curative Resection: Prognostic Factors

OBJECTIVE The long-term prognosis after hepatic resection for the treatment of hepatocellular carcinoma (HCC) has been disappointing because of the high recurrence rates in the remnant liver, which constitutes the major cause of death. The purpose of this study was to identify the prognostic factors for overall survival after transarterial chemoembolization (TACE) in recurrent HCC after the initial curative surgical resection. MATERIALS AND METHODS From January 2003 through October 2012, 362 patients who developed recurrent HCC after initial surgical resection and underwent TACE as the first-line therapy were retrospectively studied at a single institution in our hospital. Patients who met our inclusion criteria were followed until December 2012. Prognostic factors for overall survival were analyzed. RESULTS In total, 287 patients were enrolled. The median overall survival period was 747 days. The 1-, 2-, and 3-year overall survival rates after TACE were 72.9%, 51.8%, and 31.8%, respectively. Multivariate analysis indicated that the number of resected HCCs (≥ 2, p < 0.001), the number (≥ 2, p < 0.001) and size (> 5 cm, p = 0.022) of the recurrent HCCs, and the number of TACE sessions (≤ 3, p < 0.001) are independent risk factors for poor survival after TACE for recurrent HCC after HCC resection. CONCLUSION TACE appears to be an effective treatment of patients who experienced a recurrence after curative HCC resection. An initial solitary HCC, a solitary recurrence, and recurrent tumor mass 5 cm or smaller are statistically significant independent prognostic factors for survival.

Transarterial embolization in the management of intractable epistaxis: the angiographic findings and results based on etiologies

Abstract Conclusions: Transarterial embolization (TAE) appears to be a safe and effective treatment for patients with intractable epistaxis, despite different etiologies or angiography findings. Idiopathic epistaxis is prone to present with negative angiographic findings. Objective: To retrospectively evaluate the safety and effectiveness of TAE for intractable epistaxis, and focus on the factors of etiology and angiographic findings. Materials and methods: From March 2008 to December 2014, the data of 43 patients with intractable bleeding undergoing TAE were reviewed. The outcomes of interventional therapy were assessed according to different etiology (malignant or benign disease) and angiographic finding (positive or negative angiogram). Results: Positive angiographic findings were found in 11 of 12 cases with malignant diseases and 22 of 31 cases with benign diseases, respectively (p = 0.237). Among the 10 cases with negative angiographic findings, the negative angiography rate of idiopathic epistaxis was higher than that of epistaxis with definite etiology (p = 0.003). Bleeding was controlled successfully in all of the 43 patients after embolization. During the mean follow-up period of 24.0 ± 16.7 months, five patients relapsed. No significant difference was found in recurrence rates between malignant and benign diseases or between positive and negative angiography (p = 0.241, p = 0.704, respectively).

The CD40/CD40L system regulates rat cerebral microvasculature after focal ischemia/reperfusion via the mTOR/S6K signaling pathway

ABSTRACT Objective: The role of CD40/CD40 ligand (CD40L) in microvascular thrombosis is now widely accepted. However, the exact mechanisms linking the CD40/CD40L system and the soluble form of CD40L (sCD40L) with microvascular thrombosis are currently a topic of intensive research. The objective of this study was to assess the potential mechanisms in CD40/CD40L system-regulated microvascular thrombosis after focal ischemia/reperfusion (I/R). Methods: Rats were subjected to 60-min transient middle cerebral artery occlusion (MCAO). The experiments were divided into three groups: sham operation, MCAO, and MCAO + CD40 antagonist. Dynamic changes of serum-free sCD40L levels for 0, 1, 3, 5, 6, and 12 h by ELISA detecting kit after focal I/R were observed, and the CD40 expression levels in both platelet surface and vascular endothelial cell surface were measured by flow cytometry and immunofluorescence, respectively. Cerebral infarct volume was analyzed 12 h after reperfusion. mTOR/S6K signaling was determined by Western blot. Results: A comparison of thrombus formation between MCAO and CD40 antagonist treatment rats revealed a role for CD40 and/or CD40L in the inflammation-enhanced thrombosis responses in both of the platelet and vascular endothelial cell. MCAO rats yielded an acceleration of thrombus formation that was accompanied by increased CD40 levels in serum. The brain infarction was significantly decreased in CD40 antagonist treatment group compared to MCAO model group. The mTOR/S6K signaling was activated in MACO model than that of CD40 antagonist treatment group. Conclusions: Our findings indicate that CD40/CD40L system contributes to microvascular thrombosis and brain infarction induced by MCAO and reperfusion. The mTOR/S6K signaling pathway is involved in the regulation of cerebral microvasculature after focal I/R by CD40/CD40L. Abbreviations: AKT: protein kinase B; CD40L: CD40 ligand; CSF: cerebrospinal fluid; FITC: fluorescein isothiocyanate; I/R: ischemia/reperfusion; MCAO: middle cerebral artery occlusion; mTOR: mechanistic target of rapamycin; PE: P-phycoerythrin; sCD40L: soluble form of CD40L; TNF-a: tumor necrosis factor-alpha; WT: wild type.

Hypoxic conditioned medium derived from bone marrow mesenchymal stromal cells protects against ischemic stroke in rats: JIANG et al.

In recent years, studies have shown that the secretome of bone marrow mesenchymal stromal cells (BMSCs) contains many growth factors, cytokines, and antioxidants, which may provide novel approaches to treat ischemic diseases. Furthermore, the secretome may be modulated by hypoxic preconditioning. We hypothesized that conditioned medium (CM) derived from BMSCs plays a crucial role in reducing tissue damage and improving neurological recovery after ischemic stroke and that hypoxic preconditioning of BMSCs robustly improves these activities. Rats were subjected to ischemic stroke by middle cerebral artery occlusion and then intravenously administered hypoxic CM, normoxic CM, or Dulbecco modified Eagle medium (DMEM, control). Cytokine antibody arrays and label‐free quantitative proteomics analysis were used to compare the differences between hypoxic CM and normoxic CM. Injection of normoxic CM significantly reduced the infarct area and improved neurological recovery after stroke compared with administering DMEM. These outcomes may be associated with the attenuation of apoptosis and promotion of angiogenesis. Hypoxic preconditioning significantly enhanced these therapeutic effects. Fourteen proteins were significantly increased in hypoxic CM compared with normoxic CM as measured by cytokine arrays. The label‐free quantitative proteomics analysis revealed 163 proteins that were differentially expressed between the two groups, including 107 upregulated proteins and 56 downregulated proteins. Collectively, our results demonstrate that hypoxic CM protected brain tissue from ischemic injury and promoted functional recovery after stroke in rats and that hypoxic CM may be the basis of a potential therapy for stroke patients.