Enoxaparin ameliorates post-traumatic brain injury edema and neurologic recovery, reducing cerebral leukocyte endothelial interactions and vessel permeability in vivo

Supra-Prophylactic Doses of Enoxaparin Reduces Fibrin Deposition Without Exacerbation of Intracerebral Hemorrhage in a Rat Model of Penetrating Traumatic Brain Injury

Deep vein thrombosis and pulmonary embolism prophylaxis is an important part of trauma care. Despite an increased risk of thrombotic complications, the use of venous thrombosis chemoprophylaxis in penetrating traumatic brain injury (pTBI) patients is met with reluctance from neurosurgeons because of concern for the exacerbation of intracerebral hemorrhage. The objective of this study was to provide initial pre-clinical evidence of the effects of Lovenox (LVX) administration following pTBI with significant intracerebral hemorrhage. Sprague-Dawley rats received a penetrating ballistic-like brain injury. Animals were randomly divided into two groups following injury: LVX (25 mg/kg) or vehicle (VEH, saline). LVX or vehicle was administered subcutaneously beginning 24 h after the injury and continued daily for 7 days post-injury. A neurological assessment was performed daily and magnetic resonance imaging (MRI) was performed at baseline, 1, 2, 3, and 7 days post-injury. Following the final MRI, brains were isolated and prepared for histological analysis. Thromboelastography demonstrated dramatic anticoagulation effects which were confirmed by significant increases in partial thromboplastin time (p < 0.001). Daily neurological assessment revealed no worsening of functional deficits following LVX treatment. MRI analysis demonstrated no differences in cerebral edema or intracranial hemorrhage volumes between treatment groups at any tested post-injury time points. However, LVX elicited a significant reduction in fibrin deposition in the ipsilateral striatum and lesion site at 7 days post-injury (p < 0.05). Serum levels of beta-amyloid were decreased at 7 days following LVX treatment (p < 0.05) which may indicate neuroprotective effects but was not correlated to brain levels. The results presented indicate that administration of LVX at a dose capable of inducing anticoagulation is safe in a rodent model of pTBI without exacerbation of intracerebral hemorrhage within the first 7 days of injury.

Multi-Modal Venous ThromboembolicProphylaxis Aids in Risk Reduction Following Splenectomy in Female and Male Mice

INTRODUCTION

Splenectomy (SPLN) is associated with elevated risk of venous thromboembolic (VTE) disease. Enoxaparin (ENX) is a low-molecular-weight heparin agent used in VTE chemoprophylaxis. Early aspirin administration ameliorates postSPLN platelet hyperaggregability in male mice. Previous literature has excluded female mice, citing potential effects of estrogen on platelet count and activation as a reason. We hypothesized that multimodal therapy using aspirin and ENX would mitigate postoperative platelet aggregability in mice across sexes.

METHODS

Murine models of SPLN included both male and female mice. Treatment groups included placebo gavage, sham laparotomy, SPLN alone, SPLN and aspirin, SPLN and ENX, and SPLN with aspirin and ENX (n = 5 per group). Chemoprophylaxis dosing was initiated before SPLN. Mice were euthanized on post-operative day (POD) 1 or 3; platelet counts were obtained and blood samples were analyzed via electrical impedance aggregometry.

RESULTS

Females on POD 3 following SPLN demonstrated increased platelet count compared to female mice with no treatment intervention. Male and female mice demonstrated increased adenosine diphosphate (ADP)-induced platelet aggregability on POD 3 following SPLN compared to the placebo group. Treatment with aspirin and ENX decreased this post-SPLN platelet hyperaggregability in both sexes. Females demonstrated significantly higher ADP-mediated platelet aggregability in placebo, SPLN, and SPLN with aspirin and ENX when compared to males of identical treatment groups on POD 3.

CONCLUSIONS

Platelet hyperaggregability following SPLN is mediated primarily by ADP in both males and females, but higher relative aggregability is demonstrated in females. Early administration of dual-agent VTE chemoprophylaxis utilizing aspirin and ENX mitigates this hyperaggregability and may aid in VTE risk reduction across sexes.

Propensity weighted analysis of chemical venous thromboembolism prophylaxis agents in isolated severe traumatic brain injury: An EAST sponsored multicenter study

BACKGROUND

In patients with severe traumatic brain injury (TBI), clinicians must balance preventing venous thromboembolism (VTE) with the risk of intracranial hemorrhagic expansion (ICHE). We hypothesized that low molecular weight heparin (LMWH) would not increase risk of ICHE or VTE as compared to unfractionated heparin (UH) in patients with severe TBI.

METHODS

Patients ≥ 18 years of age with isolated severe TBI (AIS ≥ 3), admitted to 24 level I and II trauma centers between January 1, 2014 to December 31, 2020 and who received subcutaneous UH and LMWH injections for chemical venous thromboembolism prophylaxis (VTEP) were included. Primary outcomes were VTE and ICHE after VTEP initiation. Secondary outcomes were mortality and neurosurgical interventions. Entropy balancing (EBAL) weighted competing risk or logistic regression models were estimated for all outcomes with chemical VTEP agent as the predictor of interest.

RESULTS

984 patients received chemical VTEP, 482 UH and 502 LMWH. Patients on LMWH more often had pre-existing conditions such as liver disease (UH vs LMWH 1.7 % vs. 4.4 %, p = 0.01), and coagulopathy (UH vs LMWH 0.4 % vs. 4.2 %, p < 0.001). There were no differences in VTE or ICHE after VTEP initiation. There were no differences in neurosurgical interventions performed. There were a total of 29 VTE events (3 %) in the cohort who received VTEP. A Cox proportional hazards model with a random effect for facility demonstrated no statistically significant differences in time to VTE across the two agents (p = 0.44). The LMWH group had a 43 % lower risk of overall ICHE compared to the UH group (HR = 0.57: 95 % CI = 0.32-1.03, p = 0.062), however was not statistically significant.

CONCLUSION

In this multi-center analysis, patients who received LMWH had a decreased risk of ICHE, with no differences in VTE, ICHE after VTEP initiation and neurosurgical interventions compared to those who received UH. There were no safety concerns when using LMWH compared to UH.

LEVEL OF EVIDENCE

Level III, Therapeutic Care Management.

Venous thromboembolism chemoprophylaxis in geriatric trauma patients with isolated severe traumatic brain injury

PURPOSE

Low-molecular-weight-heparin (LMWH) has been shown to be associated with a decreased risk of venous thromboembolism (VTE) and mortality compared to unfractionated heparin (UH) in severe traumatic brain injury (TBI). The aim of this study was to see if this association persists among a subset of patients, namely elderly patients with isolated TBI.

METHODS

This Trauma Quality Improvement Project (TQIP) database study included patients ≥ 65 years old with severe TBI (Abbreviated injury score [AIS] ≥ 3) that received either LMWH or UH for VTE prophylaxis. Patients with associated severe injuries (extracranial AIS ≥ 3), transferals, deaths < 72-h, hospitalization < 2 days, VTE chemoprophylaxis other than UH or LMWH, or with a history of bleeding diathesis were excluded. The association between VTE, deep vein thrombosis (DVT), and pulmonary embolism (PE) with VTE chemoprophylaxis was analyzed with multivariable analysis, subset analyses of different grades of AIS-head injury, and a 1:1 matched LWMH:UH cohort of patients.

RESULTS

Out of 14,926 patients, 11,036 (73.9%) received LMWH. Multivariate analysis showed that patients receiving LMWH had a decreased risk of mortality (OR 0.81, 95% CI 0.67-0.97, p < 0.001) but a similar risk of VTE (OR 0.83, 95% CI 0.63-1.08). Analysis according to head-AIS showed that LMWH was associated with a decreased risk of PE in patients AIS-3 but not in AIS 4 or 5. In a 1:1 matched cohort of LMWH:UH patients, the risk of PE, DVT and VTE were all similar but LMWH continued to be associated with a decreased risk of mortality (OR 0.81, CI 0.67-0.97, p = 0.023).

CONCLUSION

LMWH was associated with a decreased risk of overall mortality and reduced risk of PE compared to UH among geriatric patients with a severe head injury.

Early administration of high dose enoxaparin after traumatic brain injury

BACKGROUND

Early enoxaparin 30 mg BID administration at 24 h post-injury has been demonstrated in patients with traumatic brain injury (TBI). However this dose can also yield subtherapeutic anti-Xa levels in 30-50% of trauma patients, suggesting that larger doses may be required for adequate prophylaxis against venous thromboembolism (VTE). The safety of enoxaparin 40 mg BID in trauma patients has previously been shown - however, these studies have largely excluded TBI patients. Therefore, we sought to demonstrate the safety of early enoxaparin 40 mg BID in a low-risk group of TBI patients.

METHODS

A retrospective review of TBI patients at a Level 1 trauma center was performed. Patients with stable computed tomography (CT) of the head at 6 to 24 h post-injury who received enoxaparin 40 mg BID were included and serial GCS evaluations to identify possible clinical complications. To evaluate the safety of this dosing regimen, data was then compared to patients from our institution with similar TBI profiles who had received 5,000 units (U) of subcutaneous heparin (SQH) prophylaxis.

RESULTS

199 TBI patients were identified over a nine month period, 40/199 (19.7%) received DVT prophylaxis after traumatic injury. Of these 40, 19 (47.5%) received enoxaparin 40 mg BID and 21 (52.5%) received 5,000U of SQH. Low risk TBI patients who were either given enoxaparin (n = 7) or SQH (n = 4), demonstrated no clinical decline in mental status during their inpatient stay.

CONCLUSION

Prior studies have demonstrated that enoxaparin 40 mg BID dosing is superior to traditional VTE prophylaxis in trauma patients. However, TBI patients are often excluded from this dosing due to concern for progression. Our study showed no clinical decline in mental status in a small cohort of low-risk TBI patients who received enoxaparin 40 mg BID.

Mortality of Surgically Treated Neurotrauma in Elderly Patients and the Development of a Prediction Score: Geriatric Neurotrauma Mortality Score

BACKGROUND

As the population worldwide is aging, the need for surgery in elderly patients with neurotrauma is increasing. The aim of this study was to compare the outcome of elderly patients undergoing surgery for neurotrauma with younger patients and to identify the risk factors for mortality.

METHODS

We retrospectively analyzed consecutive patients undergoing craniotomy or craniectomy for neurotrauma at our institution from 2012 to 2019. Patients were divided into two groups (≥70 years or <70 years) and compared. The primary outcome was the 30-day mortality rate. Potential risk factors for 30-day mortality were assessed in a uni- and multivariate regression model for both age groups, forming the basis of a 30-day mortality prediction score.

RESULTS

We included 163 consecutive patients (average age 57.98 ± 19.87 years); 54 patients were ≥70 years. Patients ≥70 years showed a significantly better median preoperative Glasgow Coma Scale (GCS) score compared with young patients (P < 0.001), and fewer pupil asymmetry (P = 0.001), despite having a higher Marshall score (P = 0.07) at admission. Multivariate regression analysis identified low pre- and postoperative GCS scores and the lack of prompt postoperative prophylactic low-molecular-weight heparin treatment as risk factors for 30-day mortality. Our score showed moderate accuracy in predicting 30-day mortality with an area under the curve of 0.76.

CONCLUSIONS

Elderly patients after neurotrauma present with a better GCS at admission despite having more severe radiographic injuries. Mortality and favorable outcome rates are comparable between the age groups.

Timing of venous thromboembolism prophylaxis initiation after injury: Findings from the consensus conference to implement optimal VTE prophylaxis in trauma

ABSTRACT

Optimizing prophylaxis against venous thromboembolic events (VTEs) is a critical issue in the care of injured patients. Although these patients are at significant risk of developing VTE, they also present competing concerns related to exacerbation of bleeding from existing injuries. Especially after high-risk trauma, including injuries to the abdominal solid organs, brain, and spine, trauma providers must delineate the time period in which VTE prophylaxis successfully reduces VTE rates without encouraging bleeding. Although existing data are primarily retrospective in nature and further study is required, literature supports early VTE chemoprophylaxis initiation even for severely injured patients. Early initiation is most frequently defined as <48 hours from admission but varies from <24 hours to 72 hours and occasionally refers to time from initial trauma. Prior to chemical VTE prophylaxis initiation in patients at risk for bleeding, an observation period is necessary during which injuries must show themselves to be hemostatic, either clinically or radiographically. In the future, prospective examination of optimal timing of VTE prophylaxis is necessary. Further study of specific subsets of trauma patients will allow for development of effective VTE mitigation strategies based upon collective risks of VTE and hemorrhage progression.

A Systematic Review and Meta-Analysis on the Therapeutic Efficacy of Heparin and Low Molecular Weight Heparins in Animal Studies of Traumatic Brain Injury

The identification of effective pharmacotherapies for traumatic brain injury (TBI) remains a major challenge. Treatment with heparin and its derivatives is associated with neuroprotective effects after experimental TBI; however, the optimal dosage and method of administration, modes of action, and effects on hemorrhage remain unclear. Therefore, this review aimed to systematically evaluate, analyze, and summarize the available literature on the use of heparin and low molecular weight heparins (LMWHs) as treatment options for experimental TBI. We searched two online databases (PubMed and ISI Web of Science) to identify relevant studies. Data pertaining to TBI paradigm, animal subjects, drug administration, and all pathological and behavior outcomes were extracted. Eleven studies met our pre-specified inclusion criteria, and for outcomes with sufficient numbers, data from seven publications were analyzed in a weighted mean difference meta-analysis using a random-effects model. Study quality and risk of bias were also determined. Meta-analysis revealed that heparin and its derivatives decreased brain edema, leukocyte rolling, and vascular permeability, and improved neurological function. Further, treatment did not aggravate hemorrhage. These findings must be interpreted with caution, however, because they were determined from a limited number of studies with substantial heterogeneity. Also, overall study quality was low based on absences of data reporting, and potential publication bias was identified. Importantly, we found that there are insufficient data to evaluate the variables we had hoped to investigate. The beneficial effects of heparin and LMWHs, however, suggest that further pre-clinical studies are warranted.

LPS-Induced Coagulation and Neuronal Damage in a Mice Model Is Attenuated by Enoxaparin

Background. Due to the interactions between neuroinflammation and coagulation, the neural effects of lipopolysaccharide (LPS)-induced inflammation (1 mg/kg, intraperitoneal (IP), n = 20) and treatment with the anti-thrombotic enoxaparin (1 mg/kg, IP, 15 min, and 12 h following LPS, n = 20) were studied in C57BL/6J mice. Methods. One week after LPS injection, sensory, motor, and cognitive functions were assessed by a hot plate, rotarod, open field test (OFT), and Y-maze. Thrombin activity was measured with a fluorometric assay; hippocampal mRNA expression of coagulation and inflammation factors were measured by real-time-PCR; and serum neurofilament-light-chain (NfL), and tumor necrosis factor-α (TNF-α) were measured by a single-molecule array (Simoa) assay. Results. Reduced crossing center frequency was observed in both LPS groups in the OFT (p = 0.02), along with a minor motor deficit between controls and LPS indicated by the rotarod (p = 0.057). Increased hippocampal thrombin activity (p = 0.038) and protease-activated receptor 1 (PAR1) mRNA (p = 0.01) were measured in LPS compared to controls, but not in enoxaparin LPS-treated mice (p = 0.4, p = 0.9, respectively). Serum NfL and TNF-α levels were elevated in LPS mice (p < 0.05) and normalized by enoxaparin treatment. Conclusions. These results indicate that inflammation, coagulation, neuronal damage, and behavior are linked and may regulate each other, suggesting another pharmacological mechanism for intervention in neuroinflammation.

Delayed Cranial Decompression Rates After Initiation of Unfractionated Heparin versus Low-Molecular-Weight Heparin in Traumatic Brain Injury

BACKGROUND

Both unfractionated heparin (UH) and low-molecular-weight heparin (LMWH) are routinely used prophylactically after traumatic brain injury (TBI) to prevent deep vein thrombosis (DVT). Their comparative risk for development or worsening of intracranial hemorrhage necessitating cranial decompression is unclear. Furthermore, the absence of a specific antidote for LMWH may lead to UH being used more often for high-risk patients. This study aims to compare the incidence of delayed cranial decompression occurring after initiation of prophylactic UH versus LMWH using the National Trauma Data Bank.

METHODS

Cranial decompression procedures included craniotomy and craniectomy. Multiple imputation was used for missing data. Propensity score matching was used to account for selection bias between UH and LMWH. The 1:1 matched groups were compared using logistic regression for the primary outcome of postprophylaxis cranial decompression.

RESULTS

A total of 218,594 patients with TBI were included, with 61,998 (28.3%) receiving UH and 156,596 (71.7%) receiving LMWH as DVT prophylaxis. The UH group had higher patient age, body mass index, comorbidity rates, Injury Severity Score, and worse motor Glasgow Coma Scale score. After the UH and LMWH groups were matched for these factors, logistic regression showed lower rates of postprophylaxis cranial decompression for the LMWH group (odds ratio, 0.13; 95% confidence interval, 0.11-0.16; P < 0.001).

CONCLUSIONS

Despite the absence of a specific antidote, LMWH was associated with lower rates of need for post-DVT-prophylaxis in craniotomy/craniectomy. This finding questions the notion of UH being safer for patients with TBI because it can be readily reversed. Randomized studies are needed to elucidate causality.

Low-Molecular Weight Heparin is Superior to Unfractionated Heparin for Elderly Trauma Patients

BACKGROUND

Several studies have demonstrated that low-molecular weight heparin (LMWH) is superior to unfractionated heparin (UFH) in trauma patients. The superiority of either one has not been established for the elderly. In this study, we compared LMWH to UFH in elderly trauma patients.

METHODS

A retrospective analysis of the American College of Surgeons' Trauma Quality Improvement Program database was performed for patients aged ≥65 y. Propensity score matching was performed to minimize confounders between the two groups. Outcomes included venous thromboembolic (VTE) and bleeding events.

RESULTS

Overall, 93,987 patients were identified (mean age 77.1 ± 7.3 y, females 55,035 [58.6%]), of which 67,738 (72.1%) patients received LMWH and 26,249 (27.9%) received UFH. After Propensity score matching, LMWH was associated with a lower incidence of deep venous thrombosis (1.7% versus 2.1%, P = 0.007) and pulmonary embolisms (0.6% versus 1%, P< 0.001). LMWH was also associated with fewer bleeding complications (transfusions: 2.8% versus 3.5%, P< 0.001, procedures: 0.7% versus 0.9%, P = 0.007). Sub-analyses showed that differences in VTE rates were identified in patients with mild injuries (Injury Severity Score [ISS] <16, 0.6% versus 1.9%, P< 0.001). Differences in bleeding complications were identified in patients with injuries of mild (ISS <16, transfusions: 3% versus 3.8%, P< 0.001, surgeries: 0.3% versus 0.4%, P= 0.015) and moderate severity (ISS 16-24, transfusions: 1.9% versus 2.7%, P= 0.038, surgeries: 1% versus 1.7%, P= 0.013).

CONCLUSION

LMWH prophylaxis is superior to UFH for VTE prevention among elderly trauma patients. LMWH prophylaxis is associated with fewer bleeding complications compared to UFH in patients with injuries of mild or moderate severity.

Progression of Intracranial Hemorrhage After Chemical Prophylaxis Using Low-Molecular-Weight Heparin in Patients With Traumatic Brain Injury

INTRODUCTION

Chemical prophylaxis using low-molecular-weight heparin (LMWH) is considered a standard of care for venous thromboembolism in trauma patients. Our center performs a head computed tomography (CT) scan 24 hours after initiation with prophylactic LMWH in the setting of a known traumatic brain injury (TBI). The purpose was to determine the overall incidence of ICH progression after chemoprophylaxis in patients with a TBI.

METHODS

This retrospective study was performed at a Level I trauma center, from 1/1/2014 to 12/31/2017. Study patients were drawn from the institution's trauma registry based on Abbreviated Injury Score codes.

RESULTS

778 patients met all inclusion criteria after initial chart review. The proportion of patients with an observed radiographic progression of intracranial hemorrhage after LMWH was 5.8%. 3.1% of patients had a change in clinical management. Observed radiographic progression after LMWH prophylaxis and the presence of SDH on initial CT, the bilateral absence of pupillary response in the emergency department, and a diagnosis of dementia were found to have statistically significant correlation with bleed progression after LMWH was initiated.

CONCLUSION

Over a 4-year period, the use of CT to evaluate for radiographic progression of traumatic intracranial hemorrhage 24 hours after receiving LMWH resulted in a change in clinical management for 3.1% of patients. The odds of intracranial hemorrhage progression were approximately 6.5× greater in patients with subdural hemorrhage on initial CT, 3.1× greater in patients with lack of bilateral pupillary response in ED, and 4.2× greater in patients who had been diagnosed with dementia.

Timing of venous thromboembolic pharmacological prophylaxis in traumatic combined subdural and subarachnoid hemorrhage

BACKGROUND

The combination of subdural and subarachnoid hemorrhage is the most common intracranial bleeding. The present study evaluated the timing and type of venous thromboembolic chemoprophylaxis (VTEp) for efficacy and safety in patients with blunt head trauma with combined acute subdural and subarachnoid hemorrhage.

METHODS

Patients with isolated combined acute subdural and subarachnoid hemorrhage were extracted from the ACS-TQIP database (2013-2017). After 1:1 cohort matching of patients receiving early prophylaxis (EP, ≤48 h) versus late prophylaxis (LP, >48 h) outcomes were compared with univariable and multivariable regression analysis.

RESULTS

Multivariable regression analysis identified EP as an independent protective factor for VTE complications (OR 0.468, CI 0.293-0.748) but not mortality (p = 0.485). The adjusted risk for delayed craniectomy was not associated with EP compared to LP (p = 0.283). The type of VTEp was not associated with VTE complications (p = 0.301), mortality (p = 0.391) or delayed craniectomy (p = 0.126).

CONCLUSIONS

Early VTEp (≤48 h) was associated with fewer VTE complications in patients and did not increase the risk for craniectomies in patients with combined acute subdural and subarachnoid hemorrhage.

Venous thromboembolic pharmacological prophylaxis in severe traumatic acute subdural hematomas: Early prophylaxis is effective and safe

BACKGROUND

The purpose of this study was to evaluate the optimal timing and type of pharmacological venous thromboembolism prophylaxis (VTEp) in patients with severe blunt head trauma with acute subdural hematomas (ASDH).

METHODS

Matched cohort study using ACS-TQIP database (2013-2016) including patients with isolated ASDH. Outcomes of matched patients receiving early prophylaxis (EP, ≤48 h) and late prophylaxis (LP, >48 h) were compared with univariable and multivariable regression analysis.

RESULTS

In 1,660 matched cases VTE complications (3.1% vs 0.5%, p < 0.001) were more common in the LP compared to the EP group. Multivariable regression analysis identified EP as an independent protective factor for VTE complications (OR 0.169, p < 0.001) but not mortality (p = 0.260). The adjusted risk for delayed craniectomy was not associated with EP compared to LP (p = 0.095). LMWH was independently associated with a lower mortality (OR 0.480, p = 0.008) compared to UH.

CONCLUSIONS

Early VTEp (≤48 h) does not increase the risk for craniectomies and is independently associated with fewer VTE complications in patients with isolated ASDH. LMWH was independently associated with a lower mortality compared to UH.

Post-traumatic brain injury antithrombin III recovers Morris water maze cognitive performance, improving cued and spatial learning

BACKGROUND

Neuroinflammation and cerebral edema development following severe traumatic brain injury (TBI) affect subsequent cognitive recovery. Independent of its anticoagulant effects, antithrombin III (AT-III) has been shown to block neurovascular inflammation after severe TBI, reduce cerebral endothelial-leukocyte interactions, and decrease blood-brain barrier permeability. We hypothesized that AT-III administration after TBI would improve post-TBI cognitive recovery, specifically enhancing learning, and memory.

METHODS

Fifteen CD1 male mice were randomized to undergo severe TBI (controlled cortical impact [CCI]: velocity, 6 m/s; depth, 1 mm; diameter, 3 mm) or sham craniotomy and received either intravenous AT-III (250 IU/kg) or vehicle (VEH/saline) 15 minutes and 24 hours post-TBI. Animals underwent Morris water maze testing from 6 to 14 days postinjury consisting of cued learning trials (platform visible), spatial learning trials (platform invisible, spatial cues present), and probe (memory) trials (platform removed, spatial cues present). Intergroup differences were assessed by the Kruskal-Wallis test (p < 0.05).

RESULTS

Morris water maze testing demonstrated that cumulative cued learning (overall mean time in seconds to reach the platform on days 6-8) was worst in CCI-VEH animals (26.1 ± 2.4 seconds) compared with CCI-AT-III counterparts (20.3 ± 2.1 seconds, p < 0.01). Cumulative noncued spatial learning was also worst in the CCI-VEH group (23.4 ± 1.8 seconds) but improved with AT-III (17.6 ± 1.5 seconds, p < 0.01). In probe trials, AT-III failed to significantly improve memory ability. Animals that underwent sham craniotomy demonstrated preserved learning and memory compared with all CCI counterparts (p < 0.05).

CONCLUSION

Antithrombin III improves neurocognitive recovery weeks after TBI. This improvement is particularly related to improvement in learning but not memory function. Pharmacologic support of enhanced learning may support new skill acquisition or relearning to improve outcomes after TBI.

LEVEL OF EVIDENCE

Therapeutic/care management, level II.

Low-molecular-weight heparin versus unfractionated heparin in pediatric traumatic brain injury

OBJECTIVE

The incidence of venous thromboembolism (VTE) in patients with traumatic brain injury (TBI) has increased significantly. The Eastern Association for the Surgery of Trauma recommends using low-molecular-weight heparin (LMWH) over unfractionated heparin (UH) in pediatric patients requiring VTE prophylaxis, although this strategy is unsupported by the literature. In this study, the authors compare the outcomes of pediatric TBI patients receiving LMWH versus UH.

METHODS

The authors performed a 4-year (2014-2017) analysis of the pediatric American College of Surgeons Trauma Quality Improvement Program. All trauma patients (age ≤ 18 years) with TBI requiring thromboprophylaxis with UH or LMWH were potentially eligible for inclusion. Patients who had been transferred, had died in the emergency department, or had penetrating trauma were excluded. Patients were stratified into either the LMWH or the UH group on the basis of the prophylaxis they had received. Patients were matched on the basis of demographics, injury characteristics, vital signs, and transfusion requirements using propensity score matching (PSM). The study endpoints were VTE, death, and craniotomy after initiation of prophylaxis. Univariate analysis was performed after PSM to compare outcomes.

RESULTS

A total of 2479 patients met the inclusion criteria (mean age 15.5 ± 3.7 years and 32.0% female), of which 1570 (63.3%) had received LMWH and 909 (36.7%) had received UH. Before PSM, patients receiving UH were younger, had a lower Glasgow Coma Scale score, and had a higher Injury Severity Score. Patients treated in pediatric hospitals were more likely to receive UH (12.9% vs 9.0%, p < 0.001) than patients treated in adult hospitals. Matched patients receiving UH had a higher incidence of VTE (5.1% vs 2.9%, p = 0.03).

CONCLUSIONS

LMWH prophylaxis in pediatric TBI appears to be more effective than UH in preventing VTE. Large, multicenter prospective studies are warranted to confirm the superiority of LMWH over UH in pediatric patients with TBI. Moreover, outcomes of VTE prophylaxis in the very young remain understudied; therefore, dedicated studies to evaluate this population are needed.

The survival benefit of low molecular weight heparin over unfractionated heparin in pediatric trauma patients

INTRODUCTION

Venous thromboembolism (VTE) prophylaxis in pediatric patients is controversial and is mainly dependent on protocols derived from adult practices. Our study aimed to compare outcomes among pediatric trauma patients who received low molecular weight heparin (LMWH) compared to those who received unfractionated heparin (UFH).

METHODS

We performed 2 years (2015-2016) retrospective analysis of the Pediatrics ACS-TQIP database. Pediatric trauma patients (age ≤17) who received thromboprophylaxis with either LMWH or UFH were included. Patients were stratified into three age groups. Analysis of each subgroup and the entire cohort was performed. Outcome measures included VTE events (deep vein thrombosis [DVT] and pulmonary embolism [PE]), hospital and ICU length of stay (LOS) among survivors, and mortality. Propensity score matching was used to match the two cohorts LMWH vs UFH.

RESULTS

A matched cohort of 1,678 pediatric trauma patients was analyzed. A significant difference in survival, DVT events, and in-hospital LOS was seen in the age groups above 9 years. Overall, the patients who received LMWH had lower mortality (1.4% vs 3.6%, p<0.01), DVT (1.7% vs 3.7%, p<0.01), and hospital LOS among survivors (7 days vs 9 days, p<0.01) compared to those who received UFH. There was no significant difference in the ICU LOS among survivors and the incidence of PE between the two groups.

CONCLUSION

LMWH is associated with increased survival, lower rates of DVT, and decreased hospital LOS compared to UFH among pediatric trauma patients age 10-17 years.

LEVEL OF EVIDENCE

Level III Prophylactic.

STUDY TYPE

Prophylactic.

Antithrombin III ameliorates post-traumatic brain injury cerebral leukocyte mobilization enhancing recovery of blood brain barrier integrity

BACKGROUND

Acute traumatic coagulopathy often accompanies traumatic brain injury (TBI) and may impair cognitive recovery. Antithrombin III (AT-III) reduces the hypercoagulability of TBI. Antithrombin III and heparinoids such as enoxaparin (ENX) demonstrate potent anti-inflammatory activity, reducing organ injury and modulating leukocyte (LEU) activation, independent of their anticoagulant effect. It is unknown what impact AT-III exerts on cerebral LEU activation and blood-brain barrier (BBB) permeability after TBI. We hypothesized that AT-III reduces live microcirculatory LEU-endothelial cell (EC) interactions and leakage at the BBB following TBI.

METHODS

CD1 mice (n = 71) underwent either severe TBI (controlled cortical impact (CCI), 6-m/s velocity, 1-mm depth, and 4-mm diameter) or sham craniotomy and then received either AT-III (250 IU/kg), ENX (1.5 mg/kg), or vehicle (saline) every 24 hours. Forty-eight hours post-TBI, cerebral intravital microscopy visualized in vivo penumbral microvascular LEU-EC interactions and microvascular leakage to assess BBB inflammation/permeability. Body weight loss and the Garcia neurological test (motor, sensory, reflex, balance) served as surrogates of clinical recovery.

RESULTS

Both AT-III and ENX similarly reduced in vivo penumbral LEU rolling and adhesion (p < 0.05). Antithrombin III also reduced live BBB leakage (p < 0.05). Antithrombin III animals demonstrated the least 48-hour body weight loss (8.4 ± 1%) versus controlled cortical impact and vehicle (11.4 ± 0.5%, p < 0.01). Garcia neurological test scores were similar among groups.

CONCLUSION

Antithrombin III reduces post-TBI penumbral LEU-EC interactions in the BBB leading to reduced neuromicrovascular permeability. Antithrombin III further reduced body weight loss compared with no therapy. Further study is needed to determine if these AT-III effects on neuroinflammation affect longer-term neurocognitive recovery after TBI.

Collagen/heparin scaffold combined with vascular endothelial growth factor promotes the repair of neurological function in rats with traumatic brain injury

The objective of this study was to evaluate the therapy effects of a novel biological scaffold containing heparin, collagen and vascular endothelial growth factor (VEGF) in treating traumatic brain injury (TBI).

Timing and Type of Venous Thromboembolic Prophylaxis in Isolated Severe Liver Injury Managed Non-Operatively

BACKGROUND

The optimal timing and type of pharmacological venous thromboembolic prophylaxis (VTEp) after severe liver injury selected for nonoperative management (NOM) are controversial. The aim of this study was to assess the effect of timing and type of VTEp in severe liver injuries selected for NOM.

METHODS

ACS-TQIP database study (2013-17) including patients with blunt isolated severe liver injuries (AIS ≥ 3), selected for NOM, who received VTEp with either unfractionated heparin (UH) or low-molecular-weight heparin (LMWH). Patients who underwent laparotomy or angiointervention within 24 h or prior to the initiation of VTEp were excluded. The study population was stratified according to the timing of VTEp ≤ 48 h (EP) and > 48 h (LP) groups. Univariate and multivariate analyses were used to identify differences between the groups.

RESULTS

A total of 4074 patients was included in the study. 2004 (49.2%) received EP and 2070 (50.8%) LP. Patients with more severe injuries were more likely to receive LP than an EP [ISS 24 (19-29) vs 22 (17-27), p < 0.001]. On multivariate analysis (correcting for age, gender, comorbidities, blood pressure, GCS, ISS, type of VTEp), LP was identified as an independent risk factor for thromboembolic events (OR 1.52, p = 0.032) and mortality (OR 2.49, p = 0.031). LMWH was independently associated with lower mortality (OR 0.36, p = 0.007), compared to UH. EP did not increase the risk of laparotomy or angiointervention after starting VTEp, compared to LP (p = 0.992).

CONCLUSION

Early VTEp (≤ 48 h) is safe and independently associated with fewer thromboembolic events and a lower mortality after isolated severe liver injuries managed nonoperatively. LMWH was independently associated with improved outcomes when compared with UH.

Therapeutic Anticoagulation with Argatroban and Heparins Reduces Granulocyte Migration: Possible Impact on ECLS-Therapy?

Introduction

Anticoagulants such as argatroban and heparins (low-molecular-weight and unfractionated) play an immense role in preventing thromboembolic complications in clinical practice. Nevertheless, they can also have a negative effect on the immune system. This study is aimed at investigating the influence of these substances on polymorphonuclear neutrophils (PMNs), whose nonspecific defense mechanisms can promote thrombogenesis.

Methods

Blood samples from 30 healthy volunteers were investigated, whereby PMNs were isolated by density gradient centrifugation and incubated with 0.8 μg/mL of argatroban, 1.0 U/mL of low-molecular-weight heparin (LMWH), 1.0 U/mL of unfractionated heparin (UFH), or without drug (control). A collagen-cell mixture was prepared and filled into 3D μ-slide chemotaxis chambers (IBIDI® GmbH, Germany). Stimulation was initiated by using a chemokine gradient of n-formyl-methionine-leucyl-phenylalanine (fMLP), and microscopic observation was conducted for 4.5 hours. The cells' track length and track straightness, as well as the number of attracted granulocytes, level of ROS (reactive oxygen species) production, and NET (neutrophil extracellular traps) formation, were analyzed and categorized into migration distances and time periods.

Results

All three anticoagulants led to significantly reduced PMN track lengths, with UFH having the biggest impact. The number of tracks observed in the UFH group were significantly reduced compared to the control group. Additionally, the UFH group demonstrated a significantly lower track straightness compared to the control. ROS production and NET formation were unaffected.

Conclusion

Our data provide evidence that anticoagulants have an inhibitory effect on the extent of PMN migration and chemotactic migration efficiency, thus indicating their potential immune-modulatory and prothrombotic effects.

The Safety of Early Thromboembolic Prophylaxis in Closed Traumatic Intracranial Hemorrhage

Background

Venous thromboembolism (VTE) is a major cause of morbidity and mortality in patients with traumatic brain injury (TBI); this study is testing the safety of enoxaparin use for the prevention of venous thromboembolism in this group of patients.

Patients and Methods

From January 2016 to May 2018, 46 patients (36 males, 10 females) with closed traumatic intracranial bleeding received early (ie, within 72 hours) venous thromboembolic prophylaxis with 40 mg of enoxaparin. Patients with traumatic intracranial hemorrhage were followed up both clinically and with repeated brain computed tomography to examine the safety of enoxaparin VTE prophylaxis.

Results

The age of the patients ranged from 16–91 years (43.9±25.8 years). Glasgow coma score ranged from 5–15 (9.9±4.7). Twenty patients had mild TBI (GCS 15–13), 17 patients had moderate TBI (GCS 12–9), and nine patients had severe TBI (GCS≤8). Brain computed tomography showed variable types of brain injuries. Non-surgical management was applied for 18 patients. Craniotomy and surgical evacuation of significant (≥1cm in maximum diameter) EDH and/or SDH was carried out in 26 patients. External ventricular drain was inserted in two patients with significant IVH. Thirty-eight patients had good overall outcome, eight patients showed poor outcome. None of the reviewed patients developed clinical deterioration and/or progression of the intracranial bleeding on follow-up brain CT scans.

Conclusion

Enoxaparin is a safe prophylaxis against venous thromboembolism in patients with traumatic closed intracranial bleeding.

Multi-target approaches to CNS repair: olfactory mucosa-derived cells and heparan sulfates

Spinal cord injury (SCI) remains one of the biggest challenges in the development of neuroregenerative therapeutics. Cell transplantation is one of numerous experimental strategies that have been identified and tested for efficacy at both preclinical and clinical levels in recent years. In this Review, we briefly discuss the state of human olfactory cell transplantation as a therapy, considering both its current clinical status and its limitations. Furthermore, we introduce a mesenchymal stromal cell derived from human olfactory tissue, which has the potential to induce multifaceted reparative effects in the environment within and surrounding the lesion. We argue that no single therapy will be sufficient to treat SCI effectively and that a combination of cell-based, rehabilitation and pharmaceutical interventions is the most promising approach to aid repair. For this reason, we also introduce a novel pharmaceutical strategy based on modifying the activity of heparan sulfate, an important regulator of a wide range of biological cell functions. The multi-target approach that is exemplified by these types of strategies will probably be necessary to optimize SCI treatment.

Cerebral Microvascular Injury: A Potentially Treatable Endophenotype of Traumatic Brain Injury-Induced Neurodegeneration

Traumatic brain injury (TBI) is one the most common human afflictions, contributing to long-term disability in survivors. Emerging data indicate that functional improvement or deterioration can occur years after TBI. In this regard, TBI is recognized as risk factor for late-life neurodegenerative disorders. TBI encompasses a heterogeneous disease process in which diverse injury subtypes and multiple molecular mechanisms overlap. To develop precision medicine approaches where specific pathobiological processes are targeted by mechanistically appropriate therapies, techniques to identify and measure these subtypes are needed. Traumatic microvascular injury is a common but relatively understudied TBI endophenotype. In this review, we describe evidence of microvascular dysfunction in human and animal TBI, explore the role of vascular dysfunction in neurodegenerative disease, and discuss potential opportunities for vascular-directed therapies in ameliorating TBI-related neurodegeneration. We discuss the therapeutic potential of vascular-directed therapies in TBI and the use and limitations of preclinical models to explore these therapies.

The complexity of neuroinflammation consequent to traumatic brain injury: from research evidence to potential treatments

This review recounts the definitions and research evidence supporting the multifaceted roles of neuroinflammation in the injured brain following trauma. We summarise the literature fluctuating from the protective and detrimental properties that cytokines, leukocytes and glial cells play in the acute and chronic stages of TBI, including the intrinsic factors that influence cytokine responses and microglial functions relative to genetics, sex, and age. We elaborate on the pros and cons that cytokines, chemokines, and microglia play in brain repair, specifically neurogenesis, and how such conflicting roles may be harnessed therapeutically to sustain the survival of new neurons. With a brief review of the clinical and experimental findings demonstrating early and chronic inflammation impacts on outcomes, we focus on the clinical conditions that may be amplified by neuroinflammation, ranging from acute seizures to chronic epilepsy, neuroendocrine dysfunction, dementia, depression, post-traumatic stress disorder and chronic traumatic encephalopathy. Finally, we provide an overview of the therapeutic agents that have been tested to reduce inflammation-driven secondary pathological cascades and speculate the future promise of alternative drugs.

A concomitant bone fracture delays cognitive recovery from traumatic brain injury

BACKGROUND

Brain injury progression after severe traumatic brain injury (TBI) is associated with worsening cerebral inflammation but it is unknown how a concomitant bone fracture (BF) affects this progression. Enoxaparin (ENX) decreases penumbral leukocyte mobilization after TBI and improves neurologic recovery. We hypothesized that a concomitant BF worsens learning/memory recovery weeks after TBI and that ENX improves this recovery.

METHODS

CD1 male mice underwent controlled cortical impact or sham craniotomy with or without tibial fracture, receiving either daily ENX (0.8 mg/kg) or saline for 14 days after injury. Randomization defined four groups (Sham, TBI only, TBI + Fx, TBI + Fx + ENX, n = 5/each). Body weight loss and neurologic recovery (Garcia Neurologic Test, max score = 18) were assessed each day. Mouse learning (swimming time [s] and total distance [m] to reach the submerged platform Days 14 to 17 after TBI) and memory (swimming time [s] in platform quadrant after platform removed [probe]) was assessed by the Morris water maze. Ly-6G (cerebral neutrophil sequestration) and glial fibrillary acidic protein were evaluated by immunohistochemistry in brain tissue post mortem. Analysis of variance with Tukey's post hoc test determined significance (p < 0.05).

RESULTS

A concurrent BF worsened Garcia Neurologic Test scores post-TBI Days 2 to 4 (p < 0.01) as compared with TBI only, and ENX reversed this worsening on Day 4 (p < 0.01). Learning was significantly slower (greater swimming time and distance) in TBI + Fx versus TBI only on Day 17 (p < 0.01). This was despite similar swimming velocities in both groups, indicating intact extremity motor function. Memory was similar in isolated TBI and Sham which was significantly better than in TBI + Fx animals (p < 0.05). Glial fibrillary acidic protein-positive cells in penumbral cortex were most prevalent in TBI + Fx animals, significantly greater than in Sham (p < 0.05).

CONCLUSION

A long BF accompanying TBI worsens early neurologic recovery and subsequent learning/memory. Enoxaparin may partially counter this and improve neurologic recovery.

Early low-anticoagulant desulfated heparin after traumatic brain injury: Reduced brain edema and leukocyte mobilization is associated with improved watermaze learning ability weeks after injury

BACKGROUND

Unfractionated heparin administered immediately after traumatic brain injury (TBI) reduces brain leukocyte (LEU) accumulation, and enhances early cognitive recovery, but may increase bleeding after injury. It is unknown how non-anticoagulant heparins, such as 2,3-O desulfated heparin (ODSH), impact post-TBI cerebral inflammation and long-term recovery. We hypothesized that ODSH after TBI reduces LEU-mediated brain inflammation and improves long-term neurologic recovery.

METHODS

CD1 male mice (n = 66) underwent either TBI (controlled cortical impact [CCI]) or sham craniotomy. 2,3-O desulfated heparin (25 mg/kg [25ODSH] or 50 mg/kg [50ODSH]) or saline was administered for 48 hours after TBI in 46 animals. At 48 hours, intravital microscopy visualized rolling LEUs and fluorescent albumin leakage in the pial circulation, and the Garcia Neurologic Test assessed neurologic function. Brain edema (wet/dry ratio) was evaluated post mortem. In a separate group of animals (n = 20), learning/memory ability (% time swimming in the Probe platform quadrant) was assessed by the Morris Water Maze 17 days after TBI. Analysis of variance with Bonferroni correction determined significance (p < 0.05).

RESULTS

Compared with CCI (LEU rolling: 32.3 ± 13.7 LEUs/100 μm per minute, cerebrovascular albumin leakage: 57.4 ± 5.6%), both ODSH doses reduced post-TBI pial LEU rolling (25ODSH: 18.5 ± 9.2 LEUs/100 μm per minute, p = 0.036; 50ODSH: 7.8 ± 3.9 LEUs/100 μm per minute, p < 0.001) and cerebrovascular albumin leakage (25ODSH: 37.9 ± 11.7%, p = 0.001, 50ODSH: 32.3 ± 8.7%, p < 0.001). 50ODSH also reduced injured cerebral hemisphere edema (77.7 ± 0.4%) vs. CCI (78.7 ± 0.4 %, p = 0.003). Compared with CCI, both ODSH doses improved Garcia Neurologic Test at 48 hours. Learning/memory ability (% time swimming in target quadrant) was lowest in CCI (5.9 ± 6.4%) and significantly improved in the 25ODSH group (27.5 ± 8.2%, p = 0.025).

CONCLUSION

2,3-O desulfated heparin after TBI reduces cerebral LEU recruitment, microvascular permeability and edema. 2,3-O desulfated heparin may also improve acute neurologic recovery leading to improved learning/memory ability weeks after injury.

Timing of venous thromboprophylaxis in isolated severe pelvic fracture: Effect on mortality and outcomes

INTRODUCTION

Optimal timing of pharmacological thromboprophylaxis (VTEp) in patients with severe pelvic fractures remains unclear. The high risk of venous thromboembolic (VTE) complications after severe pelvic fractures supports early VTEp however concern for fracture-associated hemorrhage can delay initiation. Patients with pelvic fractures also frequently have additional injuries that complicate the interpretation of the VTEp safety profiles. To minimize this problem, the study included only patients with isolated severe pelvic fractures.

MATERIALS AND METHODS

The Trauma Quality Improvement Program was used to collect patients with blunt severe pelvic fractures (AIS > 3) who received VTEp with unfractionated heparin (UH) or low-molecular-weight heparin (LMWH). Patients with head, chest, spine, and abdominal injuries AIS > 3, or those with angio or operative intervention prior to VTEp were excluded. The study population was stratified according to timing of VTEp, early (<48 h) and late (>48 h). Outcomes included in-hospital mortality and VTE.

RESULTS

2752 patients were included in the study. Overall, 2007 patients (72.9%) received early VTEp, while 745 (27.1%) received late VTEp. LMWH was administered in 2349 (85.4%) and UH in 403 (14.6%). Late VTEp was associated with significantly higher incidence of VTE (4.3% vs. 2.2%, p = 0.004). Logistic regression identified late VTEp as an independent risk factor for VTE (OR 1.93, p = 0.009) and mortality (OR 4.03, p = 0.006). LMWH was an independent factor protective for both VTE and mortality (OR 0.373, p < 0.001, OR 0.266, p = 0.009, respectively).

CONCLUSION

In isolated severe pelvic fractures, early VTEp is independently associated with improved survival and fewer VTE. LMWH may be preferred over UH for this purpose.

Enoxaparin in the treatment of severe traumatic brain injury: A randomized clinical trial

Background:

Enoxaparin was shown to have a neuroprotective effect in animal models as well as a human study following traumatic brain injury. This study was conducted to assess the effect of enoxaparin on the clinical outcome of severe traumatic brain injury (TBI) and its safety.

Methods:

This study is a randomized double-blinded placebo-controlled trial. The inclusion criteria were age 16–70, a closed head injury, a postresuscitation Glasgow Coma Scale (GCS) between 5 and 8, and a latency time between the injury and entering the study of less than 5 h. The patients were randomized into enoxaparin and placebo groups. In the enoxaparin group, 0.5 mg/kg enoxaparin was injected subcutaneously every 6 h in six total doses. The two groups were compared for the occurrence of intracranial hematoma (ICH) and for clinical neurological outcome, assessed by the Glasgow Outcome Scale.

Results:

Twenty-seven patients were assigned to the placebo group and 26 to the enoxaparin group. The two groups were similar regarding baseline characteristics, including age, sex, postresuscitation GCS, and best motor response. The occurrence of new ICH or an ICH size increase was insignificantly more frequent in the enoxaparin group than the placebo group (26.9% vs. 7.4%, P = 0.076). The favorable outcome rate in the enoxaparin group was significantly higher than in the placebo group (57.7% vs. 25.9%, P = 0.019).

Conclusions:

This study showed that the early administration of enoxaparin could lead to favorable outcomes in severe TBI patients without significantly increasing cerebral hemorrhagic complications.

Cerebral Edema and Neurological Recovery after Traumatic Brain Injury Are Worsened if Accompanied by a Concomitant Long Bone Fracture

Progression of severe traumatic brain injury (TBI) is associated with worsening cerebral inflammation, but it is unknown how a concomitant bone fracture (FX) affects this progression. Enoxaparin (ENX), a low molecular weight heparin often used for venous thromboembolic prophylaxis, decreases penumbral leukocyte (LEU) mobilization in isolated TBI and improves neurological recovery. We investigated if TBI accompanied by an FX worsens LEU-mediated cerebral inflammation and if ENX alters this process. CD1 male mice underwent controlled cortical impact (CCI) or sham craniotomy with or without an open tibial FX, and received either ENX (1 mg/kg, three times/day) or saline for 2 days following injury. Randomization defined four groups (Sham, CCI, CCI+FX, CCI+FX+ENX, n = 10/group). Two days after CCI, neurological recovery was assessed with the Garcia Neurological Test (GNT); intravital microscopy (LEU rolling and adhesion, microvascular leakage) and blood hemoglobin levels were also evaluated. Penumbral cerebral neutrophil sequestration (Ly-6G immunohistochemistry [IHC]) were evaluated post-mortem. In vivo LEU rolling was greater in CCI+FX (45.2 ± 4.8 LEUs/100 μm/min) than in CCI alone (26.5 ± 3.1, p = 0.007), and was suppressed by ENX (23.2 ± 5.5, p = 0.003 vs. CCI + FX). Neurovascular permeability was higher in CCI+FX (71.1 ± 2.9%) than CCI alone (42.5 ± 2.3, p < 0.001). GNT scores were lower in CCI+FX (15.2 ± 0.2) than in CCI alone (16.3 ± 0.3, p < 0.001). Hemoglobin was lowest in the CCI+FX+ENX group, lower than in Sham or CCI. IHC demonstrated greatest polymorphonuclear neutrophil (PMN) invasion in CCI+FX in uninjured cerebral territories. A concomitant long bone FX worsens TBI-induced cerebral LEU mobilization, microvascular leakage, and cerebral edema, and impairs neurological recovery at 48 h. ENX suppresses this progression but may increase bleeding.

Apolipoprotein E4 impairs spontaneous blood brain barrier repair following traumatic brain injury

BACKGROUND

Traumatic Brain Injury (TBI) is a major cause of disability and mortality, to which there is currently no comprehensive treatment. Blood Brain Barrier (BBB) dysfunction is well documented in human TBI patients, yet the molecular mechanisms that underlie this neurovascular unit (NVU) pathology remains unclear. The apolipoprotein-E (apoE) protein has been implicated in controlling BBB integrity in an isoform dependent manner, via suppression of Cyclophilin A (CypA)-Matrix metallopeptidase-9 (MMP-9) signaling cascades, however the contribution of this pathway in TBI-induced BBB permeability is not fully investigated.

METHODS

We exposed C57Bl/6 mice to controlled cortical impact and assessed NVU and BBB permeability responses up to 21 days post-injury. We pharmacologically probed the role of the CypA-MMP-9 pathway in BBB permeability after TBI using Cyclosporin A (CsA, 20 mg/kg). Finally, as the apoE4 protein is known to be functionally deficient compared to the apoE3 protein, we used humanized APOE mice as a clinically relevant model to study the role of apoE on BBB injury and repair after TBI.

RESULTS

In C57Bl/6 mice there was an inverse relationship between soluble apoE and BBB permeability, such that damaged BBB stabilizes as apoE levels increase in the days following TBI. TBI mice displayed acute pericyte loss, increased MMP-9 production and activity, and reduced tight-junction expression. Treatment with the CypA antagonist CsA in C57Bl/6 mice attenuates MMP-9 responses and enhances BBB repair after injury, demonstrating that MMP-9 plays an important role in the timing of spontaneous BBB repair after TBI. We also show that apoe mRNA is present in both astrocytes and pericytes after TBI. We report that APOE3 and APOE4 mice have similar acute BBB responses to TBI, but APOE3 mice display faster spontaneous BBB repair than APOE4 mice. Isolated microvessel analysis reveals delayed pericyte repopulation, augmented and sustained MMP-9 expression at the NVU, and impaired stabilization of Zonula Occludens-1, Occludin and Claudin-5 expression at tight junctions in APOE4 mice after TBI compared to APOE3 mice.

CONCLUSIONS

These data confirm apoE as an important modulator of spontaneous BBB stabilization following TBI, and highlights the APOE4 allele as a risk factor for poor outcome after TBI.

Early heparin administration after traumatic brain injury: Prolonged cognitive recovery associated with reduced cerebral edema and neutrophil sequestration

BACKGROUND

Early administration of unfractionated heparin (UFH) after traumatic brain injury (TBI) reduces early in vivo circulating leukocytes (LEUs) in peri-injury penumbral brain tissue, enhancing cognitive recovery 2 days after injury. It remains unclear how long this effect lasts and if this is related to persistently accumulating LEUs in penumbral brain tissue. We hypothesized that UFH reduces LEU brain tissue sequestration resulting in prolonged cognitive recovery.

METHODS

CD1 male mice underwent either TBI by controlled cortical impact (CCI) or sham craniotomy. Unfractionated heparin (75 or 225 U/kg) or vehicle was repeatedly administered after TBI. Neurologic function (Garcia Neurological Test [maximum score = 18]) and body weight loss ratios were evaluated at 24 hours to 96 hours after TBI. Brain and lung wet-to-dry ratios, hemoglobin levels, and brain LEU sequestration (Ly6G immunohistochemistry) were evaluated 96 hours postmortem. Analysis of variance with Bonferroni correction determined significance (p < 0.05).

RESULTS

Compared with untreated CCI animals (24 hours, 14.7 ± 1.0; 48 hours, 15.5 ± 0.7; 72 hours, 15.0 ± 0.8; 96 hours, 16.5 ± 0.9), UFH75 (24 hours, 16.0 ± 1.0, p < 0.01; 48 hours, 16.5 ± 0.7, p < 0.05; 72 hours, 17.1 ± 0.6, p < 0.01; 96 hours, 17.4 ± 0.7, p < 0.05) increased cognitive recovery throughout the entire observation period after TBI. At 48 hours, UFH225 significantly worsened body weight loss (10.2 ± 4.7%) as compared with uninjured animals (5.5 ± 2.9%, p < 0.05). Both UFH75 (60.8 ± 40.9 PMNs per high-power field [HPF], p < 0.05) and UFH225 (36.0 ± 17.6 PMNs/HPF, p < 0.01) significantly decreased brain neutrophil sequestration found in untreated CCI animals (124.2 ± 44.1 PMNs/HPF) 96 hours after TBI. Compared with untreated CCI animals (78.8 ± 0.8%), UFH75 (77.3 ± 0.6%, p = 0.04) reduced cerebral edema to uninjured levels (77.4 ± 0.6%, p = 0.04 vs. CCI). Only UFH225 (10.6 ± 1.2 g/dL) resulted in lower hemoglobin than in uninjured animals (13.0 ± 1.2 g/dL, p < 0.05).

CONCLUSIONS

Heparin after TBI reduces tissue LEU sequestration and edema in injured brain for up to 4 days. This is associated with persistent improved cognitive recovery, but only when low-dose UFH is given. Early administration of UFH following TBI may blunt LEU-related cerebral swelling and slow progression of secondary brain injury.

Unfractionated heparin after TBI reduces in vivo cerebrovascular inflammation, brain edema and accelerates cognitive recovery

BACKGROUND

Severe traumatic brain injury (TBI) may increase the risk of venous thromboembolic complications; however, early prevention with heparinoids is often withheld for its anticoagulant effect. New evidence suggests low molecular weight heparin reduces cerebral edema and improves neurological recovery after stroke and TBI, through blunting of cerebral leukocyte (LEU) recruitment. It remains unknown if unfractionated heparin (UFH) similarly affects brain inflammation and neurological recovery post-TBI. We hypothesized that UFH after TBI reduces cerebral edema by reducing LEU-mediated inflammation and improves neurological recovery.

METHODS

CD1 male mice underwent either TBI by controlled cortical impact (CCI) or sham craniotomy. UFH (75 U/kg or 225 U/kg) or vehicle (VEH, 0.9% saline) was administered 2, 11, 20, 27, and 34 hours after TBI. At 48 hours, pial intravital microscopy through a craniotomy was used to visualize live brain LEUs interacting with endothelium and microvascular fluorescein isothiocyanate-albumin leakage. Neurologic function (Garcia Neurological Test, GNT) and body weight loss ratios were evaluated 24 and 48 hours after TBI. Cerebral and lung wet-to-dry ratios were evaluated post mortem. ANOVA with Bonferroni correction was used to determine significance (p < 0.05).

RESULTS

Compared to positive controls (CCI), both UFH doses reduced post-TBI in vivo LEU rolling on endothelium, concurrent cerebrovascular albumin leakage, and ipsilateral cerebral water content after TBI. Additionally, only low dose UFH (75 U/kg) improved GNT at both 24 and 48 hours after TBI. High dose UFH (225 U/kg) significantly increased body weight loss above sham at 48 hours. Differences in lung water content and blood pressure between groups were not significant.

CONCLUSIONS

UFH after TBI reduces LEU recruitment, microvascular permeability, and brain edema to injured brain. Lower UFH doses concurrently improve neurological recovery whereas higher UFH may worsen functional recovery. Further study is needed to determine if this is caused by increased bleeding from injured brain with higher UFH doses.

Heparin and Heparin-Derivatives in Post-Subarachnoid Hemorrhage Brain Injury: A Multimodal Therapy for a Multimodal Disease

Pharmacologic efforts to improve outcomes following aneurysmal subarachnoid hemorrhage (aSAH) remain disappointing, likely owing to the complex nature of post-hemorrhage brain injury. Previous work suggests that heparin, due to the multimodal nature of its actions, reduces the incidence of clinical vasospasm and delayed cerebral ischemia that accompany the disease. This narrative review examines how heparin may mitigate the non-vasospastic pathological aspects of aSAH, particularly those related to neuroinflammation. Following a brief review of early brain injury in aSAH and heparin’s general pharmacology, we discuss potential mechanistic roles of heparin therapy in treating post-aSAH inflammatory injury. These roles include reducing ischemia-reperfusion injury, preventing leukocyte extravasation, modulating phagocyte activation, countering oxidative stress, and correcting blood-brain barrier dysfunction. Following a discussion of evidence to support these mechanistic roles, we provide a brief discussion of potential complications of heparin usage in aSAH. Our review suggests that heparin’s use in aSAH is not only safe, but effectively addresses a number of pathologies initiated by aSAH.

Dose-dependent neuroprotective effect of enoxaparin on cold-induced traumatic brain injury

Recent evidence exists that enoxaparin can reduce brain injury because of its anticoagulant activity. To investigate the potential therapeutic effect of enoxaparin on cold-induced traumatic brain injury, at 20 minutes after modeling, male BALB/c mouse models of cold-induced traumatic brain injury were intraperitoneally administered 3 and 10 mg/kg enoxaparin or isotonic saline solution. Twenty-four hours later, enoxaparin at 10 mg/kg greatly reduced infarct volume, decreased cell apoptosis in the cortex and obviously increased serum level of total antioxidant status. By contrast, administration of enoxaparin at 3 mg/kg did not lead to these changes. These findings suggest that enoxaparin exhibits neuroprotective effect on cold-induced traumatic brain injury in a dose-dependent manner.

Does enoxaparin interfere with HMGB1 signaling after TBI? A potential mechanism for reduced cerebral edema and neurologic recovery

BACKGROUND

Enoxaparin (ENX) has been shown to reduce cerebral edema and improve neurologic recovery after traumatic brain injury (TBI), through blunting of cerebral leukocyte (LEU) recruitment. High mobility group box 1 (HMGB1) protein may induce inflammation through LEU activation. We hypothesized that ENX after TBI reduces LEU-mediated edema through blockade of HMGB1 signaling.

METHODS

Twenty-three CD1 mice underwent severe TBI by controlled cortical impact and were randomized to one of four groups receiving either monoclonal antibody against HMGB1 (MAb) or isotype (Iso) and either ENX (1 mg/kg) or normal saline (NS): NS + Iso (n = 5), NS + MAb (n = 6), ENX + Iso (n = 6), ENX + MAb (n = 6). ENX or NS was administered 2, 8, 14, 23 and 32 hours after TBI. MAb or Iso (25 μg) was administered 2 hours after TBI. At 48 hours, cerebral intravital microscopy served to visualize live LEU interacting with endothelium and microvascular fluorescein isothiocyanate-albumin leakage. The Neurological Severity Score (NSS) graded neurologic recovery; wet-to-dry ratios determined cerebral/lung edema. Analysis of variance with Bonferroni correction was used for statistical analyses.

RESULTS

ENX and MAb similarly reduced in vivo pial LEU rolling without demonstrating additive effect. In vivo albumin leakage was greatest in vehicle-treated animals but decreased by 25% with either MAb or ENX but by 50% when both were combined. Controlled cortical impact-induced cerebral wet-to-dry ratios were reduced by MAb or ENX without additive effect. Postinjury lung water was reduced by ENX but not by MAb. Neurologic recovery at 24 hours and 48 hours was similarly improved with ENX, MAb, or both treatments combined.

CONCLUSION

Mirroring ENX, HMGB1 signaling blockade reduces LEU recruitment, cerebrovascular permeability, and cerebral edema following TBI. ENX further reduced lung edema indicating a multifaceted effect beyond HMGB1 blockade. Further study is needed to determine how ENX may play a role in blunting HMGB1 signaling in brain injury patients.