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Blocking autofluorescence in brain tissues affected by ischemic stroke, hemorrhagic stroke, or traumatic brain injury.

ABSTRACT: Autofluorescence is frequently observed in animal tissues, interfering with an experimental analysis and leading to inaccurate results. Sudan black B (SBB) is a staining dye widely used in histological studies to eliminate autofluorescence. In this study, our objective was to characterize brain tissue autofluorescence present in three models of acute brain injury, including collagenase-induced intracerebral hemorrhage (ICH), traumatic brain injury (TBI), and middle cerebral artery occlusion, and to establish a simple method to block autofluorescence effectively. Using fluorescence microscopy, we examined autofluorescence in brain sections affected by ICH and TBI. In addition, we optimized a protocol to block autofluorescence with SBB pretreatment and evaluated the reduction in fluorescence intensity. Compared to untreated, pretreatment with SBB reduced brain tissue autofluorescence in the ICH model by 73.68% (FITC), 76.05% (Tx Red), and 71.88% (DAPI), respectively. In the TBI model, the ratio of pretreatment to untreated decreased by 56.85% (FITC), 44.28% (Tx Red), and 46.36% (DAPI), respectively. Furthermore, we tested the applicability of the protocol using immunofluorescence staining or Cyanine-5.5 labeling in the three models. SBB treatment is highly effective and can be applied to immunofluorescence and fluorescence label imaging techniques. SBB pretreatment effectively reduced background fluorescence but did not significantly reduce the specific fluorescence signal and greatly improved the signal-to-noise ratio of fluorescence imaging. In conclusion, the optimized SBB pretreatment protocol blocks brain section autofluorescence of the three acute brain injury models.

SUBMITTER: Wang S

PROVIDER: S-EPMC10258339 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

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Blocking autofluorescence in brain tissues affected by ischemic stroke, hemorrhagic stroke, or traumatic brain injury.

Wang Shaoshuai S Ren Xiuhua X Wang Junmin J Peng Qinfeng Q Niu Xiaoyu X Song Chunhua C Li Changsheng C Jiang Chao C Zang Weidong W Zille Marietta M Fan Xiaochong X Chen Xuemei X Wang Jian J

Frontiers in immunology 20230529

Autofluorescence is frequently observed in animal tissues, interfering with an experimental analysis and leading to inaccurate results. Sudan black B (SBB) is a staining dye widely used in histological studies to eliminate autofluorescence. In this study, our objective was to characterize brain tissue autofluorescence present in three models of acute brain injury, including collagenase-induced intracerebral hemorrhage (ICH), traumatic brain injury (TBI), and middle cerebral artery occlusion, and ...[more]

PMID: 37313416

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Project description:OBJECT There is limited literature available to guide transfusion practices for patients with severe traumatic brain injury (TBI). Recent studies have shown that maintaining a higher hemoglobin threshold after severe TBI offers no clinical benefit. The present study aimed to determine if a higher transfusion threshold was independently associated with an increased risk of progressive hemorrhagic injury (PHI), thereby contributing to higher rates of morbidity and mortality. METHODS The authors performed a secondary analysis of data obtained from a recently performed randomized clinical trial studying the effects of erythropoietin and blood transfusions on neurological recovery after severe TBI. Assigned hemoglobin thresholds (10 g/dl vs 7 g/dl) were maintained with packed red blood cell transfusions during the acute phase after injury. PHI was defined as the presence of new or enlarging intracranial hematomas on CT as long as 10 days after injury. A severe PHI was defined as an event that required an escalation of medical management or surgical intervention. Clinical and imaging parameters and transfusion thresholds were used in a multivariate Cox regression analysis to identify independent risk factors for PHI. RESULTS Among 200 patients enrolled in the trial, PHI was detected in 61 patients (30.5%). The majority of patients with PHI had a new, delayed contusion (n = 29) or an increase in contusion size (n = 15). The mean time interval between injury and identification of PHI was 17.2 ± 15.8 hours. The adjusted risk of severe PHI was 2.3 times higher for patients with a transfusion threshold of 10 g/dl (95% confidence interval 1.1-4.7; p = 0.02). Diffuse brain injury was associated with a lower risk of PHI events, whereas higher initial intracranial pressure increased the risk of PHI (p < 0.001). PHI was associated with a longer median length of stay in the intensive care unit (18.3 vs 14.4 days, respectively; p = 0.04) and poorer Glasgow Outcome Scale scores (42.9% vs 25.5%, respectively; p = 0.02) at 6 months. CONCLUSIONS A higher transfusion threshold of 10 g/dl after severe TBI increased the risk of severe PHI events. These results indicate the potential adverse effect of using a higher hemoglobin transfusion threshold after severe TBI.

Project description:Traumatic brain injury (TBI) is often accompanied by hemorrhage, and treatment of hemorrhagic shock (HS) after TBI is particularly challenging because the two therapeutic treatment strategies for TBI and HS often conflict. Ischemia/reperfusion injury from HS resuscitation can be exaggerated by TBI-induced loss of autoregulation. In HS resuscitation, the goal is to restore lost blood volume, while in the treatment of TBI the priority is focused on maintenance of adequate cerebral perfusion pressure and avoidance of secondary bleeding. In this study, we investigate the responses to resuscitation from severe HS after TBI in rats, using fresh blood, polymerized human hemoglobin (PolyhHb), and lactated Ringer's (LR). Rats were subjected to TBI by pneumatic controlled cortical impact. Shortly after TBI, HS was induced by blood withdrawal to reduce mean arterial pressure (MAP) to 35-40 mmHg for 90 min before resuscitation. Resuscitation fluids were delivered to restore MAP to ~ 65 mmHg and animals were monitored for 120 min. Increased systolic blood pressure variability (SBPV) confirmed TBI-induced loss of autoregulation. MAP after resuscitation was significantly higher in the blood and PolyhHb groups compared to the LR group. Furthermore, blood and PolyhHb restored diastolic pressure, while this remained depressed for the LR group, indicating a loss of vascular tone. Lactate increased in all groups during HS, and only returned to baseline level in the blood reperfused group. The PolyhHb group possessed lower SBPV compared to LR and blood groups. Finally, sympathetic nervous system (SNS) modulation was higher for the LR group and lower for the PolyhHb group compared to the blood group after reperfusion. In conclusion, our results suggest that PolyhHb could be an alternative to blood for resuscitation from HS after TBI when blood is not available, assuming additional testing demonstrate similar favorable results. PolyhHb restored hemodynamics and oxygen delivery, without the logistical constraints of refrigerated blood.

Project description:BackgroundNo agents that are specifically neuroprotective are currently approved to emergently treat patients with traumatic brain injury (TBI). The histone deacetylase inhibitor, high-dose valproic acid (VPA) has been shown to have cytoprotective potential in models of combined TBI and hemorrhagic shock, but it has not been tested in an isolated TBI model. We hypothesized that VPA, administered after isolated TBI, will penetrate the injured brain, attenuate the lesion size, and activate prosurvival pathways.MethodsYorkshire swine were subjected to severe TBI by cortical impact. One hour later, animals were randomized to VPA treatment (150 mg/kg delivered intravenously for 1 hour; n = 4) or control (saline vehicle; n = 4) groups. Seven hours after injury, animals were sacrificed, and brain lesion size was measured. Mass spectrometry imaging was used to visualize and quantitate brain tissue distribution of VPA. Sequential serum samples were assayed for key biomarkers and subjected to proteomic and pathway analysis.ResultsBrain lesion size was 50% smaller (p = 0.01) in the VPA-treated animals (3,837 ± 948 mm) compared with the controls (1,900 ± 614 mm). Endothelial regions had eightfold higher VPA concentrations than perivascular regions by mass spectrometry imaging, and it readily penetrated the injured brain tissues. Serum glial fibrillary acid protein was significantly lower in the VPA-treated compared with the control animals (p < 0.05). More than 500 proteins were differentially expressed in the brain, and pathway analysis revealed that VPA affected critical modulators of TBI response including calcium signaling pathways, mitochondria metabolism, and biosynthetic machinery.ConclusionValproic acid penetrates injured brain tissues and exerts neuroprotective and prosurvival effects that resulted in a significant reduction in brain lesion size after isolated TBI. Levels of serum biomarkers reflect these changes, which could be useful for monitoring the response of TBI patients during clinical studies.

Dataset Information

Blocking autofluorescence in brain tissues affected by ischemic stroke, hemorrhagic stroke, or traumatic brain injury.

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Blocking autofluorescence in brain tissues affected by ischemic stroke, hemorrhagic stroke, or traumatic brain injury.

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