Fabian Arnberg

Mortality in vitamin K antagonist-related intracerebral bleeding treated with plasma or 4-factor prothrombin complex concentrate

Prothrombin complex concentrates (PCC) can rapidly normalise prolonged prothrombin time, induced by vitamin K antagonists (VKA). We conducted a multicentre retrospective study to investigate whether reversal of VKA coagulopathy with 4-factor PCC improves the survival of patients with VKA-related intracerebral haemorrhage as compared to plasma.We included 135 consecutive patients with VKA-related intracerebral haemorrhage treated either with plasma (mainly in Canada) or 4-factor PCC (The Netherlands and Sweden) for the reversal of VKA. Data on characteristics of the patients and the haemorrhage were collected. The volume of intracerebral haematoma was calculated from the first computed tomography (CT) scan. The unadjusted and adjusted odds ratio (OR) for 30-day all-cause mortality in both treatment groups was compared using logistic regression. Patients who received plasma (n=35, median 4 units) more often had diabetes, antiplatelet therapy, and intraventricular haemorrhage on the initial CT scans than patients who received PCC (n=100, median 22.5 IU/kg [interquartile range 20-26 IU], median of total dose 1,700 IU). The volume of intracerebral haematoma was larger in the plasma-treated group compared to the PCC-treated group (haematoma, mean 64.5 vs 36.0 cm³; p=0.021). The unadjusted OR for all-cause 30-day mortality in the PCC group was 0.40 (95% confidence interval, 0.18-0.87; p=0.021) compared to the plasma group. After adjusting for the haematoma volume, bleeding localisation and age, the effect of PCC on mortality became non-significant. In conclusion, treatment with 4-factor PCC for VKA reversal in patients with intracerebral haemorrhage does not seem to reduce the 30-day all-cause mortality compared to plasma.

Image-Guided Method in the Rat for Inducing Cortical or Striatal Infarction and for Controlling Cerebral Blood Flow Under MRI

Background and Purpose— Experimental models are essential for research on ischemic stroke, the second most common cause of death worldwide. The failure of clinical trials on neuroprotective treatment may be due in part to poor animal models. To push the translation of new therapies, we describe a new rat model that captures key elements of human brain ischemia. The model includes imaging and neurointerventional tools that represent the near future of clinical diagnosis and treatment of stroke. Methods— Using Sprague-Dawley rats (n=26), we navigated a microwire with fluoroscopy and MRI guidance from the ventral tail artery to 2 different positions in the middle cerebral artery to establish local occlusion. Animals were scanned with 9.4-T MRI before occlusion, during ischemia, and after reperfusion. Results— We detected stroke lesions, corresponding to the level of occlusion, in all animals by diffusion-weighted and T2 images. We measured lesion volume (mm3±SD) on T2 scans at 24 hours to be 23.2±29.8 in the somatosensory cortex group and 107.9±80 in the striatum group. Conclusion— We present a new rat model for focal stroke with the possibility to cause lesions in different regions of the brain under fluoroscopic and MRI control. The model will be highly useful for extended studies on the ischemic penumbra, alterations in neural connectivity, and for investigating neurotransmitter-mediated events and biochemical changes in the hyperacute phase of brain ischemia. Also, the model uses clinical routine microcatheters facilitating superselective administration of therapeutics directly to the cerebral circulation.

Imaging of a Clinically Relevant Stroke Model Glucose Hypermetabolism Revisited

Background and Purpose— Ischemic stroke has been shown to cause hypermetabolism of glucose in the ischemic penumbra. Experimental and clinical data indicate that infarct-related systemic hyperglycemia is a potential therapeutic target in acute stroke. However, clinical studies aiming for glucose control in acute stroke have neither improved functional outcome nor reduced mortality. Thus, further studies on glucose metabolism in the ischemic brain are warranted. Methods— We used a rat model of stroke that preserves collateral flow. The animals were analyzed by [2-18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography or magnetic resonance imaging during 90-minute occlusion of the middle cerebral artery and during 60 minutes after reperfusion. Results were correlated to magnetic resonance imaging of cerebral blood flow, diffusion of water, lactate formation, and histological data on cell death and blood–brain barrier breakdown. Results— We detected an increased [2-18F]-2-fluoro-2-deoxy-D-glucose uptake within ischemic regions succumbing to infarction and in the peri-infarct region. Magnetic resonance imaging revealed impairment of blood flow to ischemic levels in the infarct and a reduction of cerebral blood flow in the peri-infarct region. Magnetic resonance spectroscopy revealed lactate in the ischemic region and absence of lactate in the peri-infarct region. Immunohistochemical analyses revealed apoptosis and blood–brain barrier breakdown within the infarct. Conclusions— The increased uptake of [2-18F]-2-fluoro-2-deoxy-D-glucose in cerebral ischemia most likely reflects hypermetabolism of glucose meeting increased energy needs of ischemic and hypoperfused brain tissue, and it occurs under both anaerobic and aerobic conditions measured by local lactate production. Infarct-related systemic hyperglycemia could serve to facilitate glucose supply to the ischemic brain. Glycemic control by insulin treatment could negatively influence this mechanism.

Metabolism of Epidermal Growth Factor Receptor Targeting Probe [11C]PD153035: Impact on Biodistribution and Tumor Uptake in Rats

Several tracers have been evaluated as probes for noninvasive epidermal growth factor receptor (EGFR) quantification with PET. One of the most promising candidates is the 11C-labeled analog of the EGFR tyrosine kinase inhibitor PD153035. However, previous in vitro studies indicated extensive metabolism of the tracer, which could be disadvantageous for the assessment of receptor density in vivo. The aim of this study was to investigate the in vivo metabolism of [11C]PD153035 to determine whether alterations in metabolite formation are accompanied by changes in biodistribution and tumor uptake. Methods: EGFR-overexpressing human epidermoid carcinoma xenografts in rats were used in all examinations of tumor uptake. Cytochrome P450 enzymes of subfamilies CYP2D and CYP3A were inhibited before intravenous injection of [11C]PD153035 into healthy and tumor-bearing male rats. Samples were taken from arterial blood and urine, and the occurrence of radioactive metabolites was assessed with radio–high-performance liquid chromatography. Dynamic PET examinations of healthy and tumor-bearing animals were performed. In 1 rat, the effect of local intraarterial administration was examined. Results: [11C]PD153035 labeled at position 6 was metabolized extensively in vivo in male rats, resulting in very low levels of the intact tracer in plasma only minutes after injection. The major identified radiolabeled metabolites found were the N-oxide and metabolites arising from O demethylation at position 7. They were reduced by inhibition of CYP2D and CYP3A enzymes. PET revealed enzyme activity–dependent changes in the radioactivity distribution in the liver and tumors. Local administration of [11C]PD153035 greatly increased radioactivity levels in the adjacent tumor compared with levels typically found after intravenous administration. The highest tumor-to-muscle ratio at 60 min after intravenous injection was found in the untreated animals, whereas the overall highest ratio was found in the tumor near the intraarterial administration site. Conclusion: We suggest that the metabolism of [11C]PD153035 should be taken into consideration when this tracer is used to quantify EGFR expression, as our results indicated that the distribution of radioactivity to EGFR-overexpressing tumors was affected by the rate of metabolism and the route of administration.

Intra-arterial Administration of Placenta-Derived Decidual Stromal Cells to the Superior Mesenteric Artery in the Rabbit: Distribution of Cells, Feasibility, and Safety.

Selective administration of mesenchymal stromal cells to the mesenteric arteries is a potential technique to overcome pulmonary trapping and increase the density of transplanted cells in extensive mural inflammation of the intestine, such as in inflammatory bowel disease and graft-versus-host disease. We injected 5 × 106 111In-oxine-labeled human decidual stromal cells (DSCs) to the rabbit superior mesenteric artery (SMA) using clinical routine catheters guided by an angiographical system under sterile conditions. We used longitudinal single-photon emission tomography at 6 h and at 1, 2, and 5 days to assess trafficking and distribution of DSCs. We used digital subtraction angiography, computed tomography, and hematoxylin and eosin stainings to determine biodistribution of cells and to assess safety end points. We found that selective injection of human DSCs to the rabbit SMA does not result in acute embolic complications. Furthermore, we found that IV administration resulted in extensive retention of the radiolabeled DSCs in the lungs, corroborating previous studies on pulmonary trapping. In sharp contrast, selective injections to the SMA resulted in uptake distributed in the intestine supplied by the SMA and in the liver, indicating that this approach could significantly increase the fraction of injected DSCs reaching the target tissue.

Preserved Collateral Blood Flow in the Endovascular M2CAO Model Allows for Clinically Relevant Profiling of Injury Progression in Acute Ischemic Stroke

Interventional treatment regimens have increased the demand for accurate understanding of the progression of injury in acute ischemic stroke. However, conventional animal models severely inhibit collateral blood flow and mimic the malignant infarction profile not suitable for treatment. The aim of this study was to provide a clinically relevant profile of the emergence and course of ischemic injury in cases suitable for acute intervention, and was achieved by employing a M2 occlusion model (M2CAO) that more accurately simulates middle cerebral artery (MCA) occlusion in humans. Twenty-five Sprague-Dawley rats were subjected to Short (90 min), Intermediate (180 min) or Extended (600 min) transient M2CAO and examined longitudinally with interleaved diffusion-, T2- and arterial spin labeling perfusion-weighted magnetic resonance imaging before and after reperfusion. We identified a rapid emergence of cytotoxic edema within tissue regions undergoing infarction, progressing in several distinct phases in the form of subsequent moderation and then reversal at 230 min (p < 0.0001). We identified also the early emergence of vasogenic edema, which increased consistently before and after reperfusion (p < 0.0001). The perfusion of the penumbra correlated more strongly to the perfusion of adjacent tissue regions than did the perfusion of regions undergoing infarction (p = 0.0088). This was interpreted as an effect of preserved collateral blood flow during M2CAO. Accordingly, we observed only limited recruitment of penumbra regions to the infarction core. However, a gradual increase in infarction size was still occurring as late as 10 hours after M2CAO. Our results indicate that patients suffering MCA branch occlusion stand to benefit from interventional therapy for an extended time period after the emergence of ischemic injury.

Selective intra-arterial administration of 18F-FDG to the rat brain — effects on hemispheric uptake

IntroductionThe purpose of this study was to investigate the radioligand uptake and iodine contrast distribution in the intra- and extracranial circulation of the rat, after intra-arterial injections to the common carotid artery and different parts of the internal carotid artery.MethodsAll animal experiments were carried out in accordance with Karolinska Institutet’s guidelines and were approved by the local laboratory animal ethics committee. We used clinical neurointerventional systems to place microcatheters in the extra- or intracranial carotid artery of 15 Sprague–Dawley rats. Here, injection dynamics of iodine contrast was assessed using digital subtraction angiography. Maintaining the catheter position, the animals were placed in a micro PET and small-animal positron emission tomography (PET) was used to analyze injections [2-18F]-2-fluoro-2-deoxy-d-glucose (18F-FDG).ResultsMicrocatheters had to be placed in the intracranial carotid artery (iICA) for the infusate to distribute to the brain. Selective injection via the iICA resulted in a 9-fold higher uptake of 18F-FDG in the injected hemisphere (p < 0.005) compared to both intravenous and more proximal carotid artery injections. Furthermore, selective injection gave a dramatically improved contrast between the brain and extracranial tissue.ConclusionIntra-arterial injection increases the cerebral uptake of a radiotracer dramatically compared to systemic injection. This technique has potential applications for endovascular treatment of malignancies allowing intra-interventional modifications of injection strategy, based on information on tumor perfusion and risk to surrounding normal parenchyma. Furthermore the technique may increase diagnostic sensitivity and avoid problems due to peripheral pharmacological barriers and first passage metabolism of labile tracers.

Intra-arterial chemotherapy for retinoblastoma in Sweden - evaluation of treatment efficacy and complications

Editor, O ver the last 20 years, delivery of chemotherapy selectively to the ophthalmic artery in the management of retinoblastoma has been developed and reported as highly successful, by a few large specialized centres in Japan and North America (Gobin et al. 2011; Suzuki et al. 2011; Shields et al. 2014). Today, the evidence for intra-arterial chemotherapy (IACT) is based on a large number of publications presenting data from a small number of large patient cohorts treated at the aforementioned centres (Yousef et al. 2016). With high success rates in avoiding enucleation combined with a relatively low complication rate, IACT is now considered as first-line standard care at these centres, and in 2011, IACT had been performed at tertiary referral hospitals in 26 highand middleincome countries (Gobin et al. 2011). Despite the broad implementation of IACT in recent years, with the awareness of the lack of high-level evidence, no prospective multicentre clinical trial on IACT has yet been presented and there are uncertainties regarding the outcomes when IACT is introduced at and performed by clinical centres below a critical patient volume (Yousef et al. 2016). Retinoblastoma is diagnosed in six to eight children in Sweden yearly (Seregard et al. 2004; Bartuma et al. 2014). Prior to 2012, primary treatment in Sweden for children with uniand bilateral small tumours with potential salvage of vision consisted of systemic chemotherapy in combination with focal therapies, such as brachytherapy, transpupillary thermotherapy, laser photocoagulation or fractionated external radiotherapy (Seregard et al. 2004; Bartuma et al. 2014). Enucleation served as the single treatment option for large tumours and in advanced retinoblastoma failing primary treatment (Seregard et al. 2004; Bartuma et al. 2014). The Karolinska University Hospital in collaborationwith St Erik EyeHospital introduced IACT for retinoblastoma in Sweden 2012. The neurointerventional unit at Karolinska serves as a tertiary referral centre for treatment of a wide array of neurovascular diseases. We report our experience introducing IACT to retinoblastoma patients from the relatively small population of Sweden to provide clinicians in centres with similar conditions an estimate of success rates and treatment complications (Table 1). Thirteen patients with intraocular retinoblastoma received IACT with melphalan between 2012 and 2015 in Sweden. The outcome measures were globe salvage and treatment complications. A total number of 39 attempts of IACT were performed in 13 patients and 13 eyes. Two patients were excluded due to aberrant vascular anatomy. Melphalan delivery was successful in 30 procedures (77%). Globe salvage was achieved in eight of 11 eyes (73%). A total of 33 adverse events were observed in 13 patients. The most common event was nausea post-treatment (31%). Three adverse events required medical intervention and/or hospitalization. Cerebral embolization was detected angiographically in two patients without evidence of neurological deficit or ischaemic injury at clinical examination and follow-up magnetic resonance imaging (MRI). In conclusion, we report globe salvage rates and complications comparable to rates presented in a recent systematic review, although we did not reach the outstanding injection success rates reported by internationally leading centres. We encountered the previously unreported complication of procedure-related cerebral embolism. Although not leading to detectable ischaemic injury, we feel that this finding is an important contribution in the ongoing worldwide documentation of this technique.

L-N-Iminoethyl-lysine after experimental brain trauma attenuates cellular proliferation and astrocyte differentiation

BACKGROUND The effects, and thereby possible benefit, of inhibiting nitric oxide synthases (NOS) after brain injury are not fully understood. Nitric oxide (NO) has both neuroprotective and damaging features, and its effect on the cellular proliferation and differentiation that occurs in response to traumatic brain injury (TBI) is largely unknown. This study was undertaken to investigate the effects of the selective inducible NOS-inhibitor, L-N-iminoethyl-lysine (L-NIL), on proliferating cell populations in rat brain areas with self-renewing capacity. METHODS A brain contusion was produced using a weight-drop model in rats. Animals received treatment with L-NIL or saline, and were killed after 6 days. Brain sections were stained with a cell marker of proliferation, Ki67, to detect dividing cells in the hippocampus, perilesional zone and the subventricular zone (SVZ). RESULTS A significant decrease of proliferating cells was seen in the SVZ bilaterally in L-NIL-treated animals compared to controls. Hippocampal proliferation showed a tendency to decrease in L-NIL-treated animals that did not reach statistical significance. Perilesional proliferation was equal in the treatment group and controls. The percentage of proliferating GFAP expressing cells was, however, lower in L-NIL-treated animals. The proliferating cell populations were predominantly immunoreactive for GFAP, while a smaller population was immunoreactive for Nestin. The inhibition of inducible NOS with L-NIL attenuated the level of cellular proliferation and influenced the differentiation of astrocytes at 6 days after experimental brain contusion. CONCLUSIONS Our results confirmed that reactive glial cells dominated the proliferating cell population after TBI and suggested that NO-regulated mechanisms are relevant for post-traumatic cellular proliferation and differentiation, since NO inhibition decreased the number of proliferating cells in the SVZ and the proportion of proliferating cells expressing GFAP, a marker of glial proliferation.