Novel image analysis tool for rapid screening of cell morphology in preclinical animal models of disease

The field of cell biology has seen major advances in both cellular imaging modalities and the development of automated image analysis platforms that increase rigor, reproducibility, and throughput for large imaging data sets. However, there remains a need for tools that provide accurate morphometric analysis of single cells with complex, dynamic cytoarchitecture in a high-throughput and unbiased manner. We developed a fully automated image-analysis algorithm to rapidly detect and quantify changes in cellular morphology using microglia cells, an innate immune cell within the central nervous system, as representative of cells that exhibit dynamic and complex cytoarchitectural changes. We used two preclinical animal models that exhibit robust changes in microglia morphology: (1) a rat model of acute organophosphate intoxication, which was used to generate fluorescently labeled images for algorithm development; and (2) a rat model of traumatic brain injury, which was used to validate the algorithm using cells labeled using chromogenic detection methods. All ex vivo brain sections were immunolabeled for IBA-1 using fluorescence or diaminobenzidine (DAB) labeling, images were acquired using a high content imaging system and analyzed using a custom-built algorithm. The exploratory data set revealed eight statistically significant and quantitative morphometric parameters that distinguished between phenotypically distinct groups of microglia. Manual validation of single-cell morphology was strongly correlated with the automated analysis and was further supported by a comparison with traditional stereology methods. Existing image analysis pipelines rely on high-resolution images of individual cells, which limits sample size and is subject to selection bias. However, our fully automated method integrates quantification of morphology and fluorescent/chromogenic signals in images from multiple brain regions acquired using high-content imaging. In summary, our free, customizable image analysis tool provides a high-throughput, unbiased method for accurately detecting and quantifying morphological changes in cells with complex morphologies.

Identification of Demographic and Clinical Prognostic Factors in Traumatic Intraventricular Hemorrhage

BACKGROUND

The presence of traumatic intraventricular hemorrhage (tIVH) following traumatic brain injury (TBI) is associated with worse neurological outcome. The mechanisms by which patients with tIVH have worse outcome are not fully understood and research is ongoing, but foundational studies that explore prognostic factors within tIVH populations are also lacking. This study aimed to further identify and characterize demographic and clinical variables within a subset of patients with TBI and tIVH that may be implicated in tIVH outcome.

METHODS

In this observational study, we reviewed a large prospective TBI database to determine variables present on admission that predicted neurological outcome 6 months after injury. A review of 7,129 patients revealed 211 patients with tIVH on admission and 6-month outcome data. Hypothesized risk factors were tested in univariate analyses with significant variables (p < 0.05) included in logistic and linear regression models. Following the addition of either the Rotterdam computed tomography or Glasgow Coma Scale (GCS) score, we employed a backward selection process to determine significant variables in each multivariate model.

RESULTS

Our study found that that hypotension (odds ratio [OR] = 0.35, 95% confidence interval [CI] = 0.13-0.94, p = 0.04) and the hemoglobin level (OR = 1.33, 95% CI = 1.09-1.63, p = 0.006) were significant predictors in the Rotterdam model, whereas only the hemoglobin level (OR = 1.29, 95% CI = 1.06-1.56, p = 0.01) was a significant predictor in the GCS model.

CONCLUSIONS

This study represents one of the largest investigations into prognostic factors for patients with tIVH and demonstrates that admission hemoglobin level and hypotension are associated with outcomes in this patient population. These findings add value to established prognostic scales, could inform future predictive modeling studies, and may provide potential direction in early medical management of patients with tIVH.

An implantable helmet for studying repeat TBI

An estimated 3.8 million traumatic brain injuries (TBI) occur each year, the majority classified as mild. Interest in models of mild and repeat mild TBI has grown due to reports of lasting morbidity following sports- or combat-related injury. There remains a paucity of data linking cellular or systems-related mechanisms to behavioral outcomes following repeat mild TBI, particularly in adolescent and adult rats. It is critical, therefore, to develop flexible models to evaluate which parameters of injury are associated with brain vulnerability or poor chronic outcome compared to normal recovery. While there are several existing models of repeat mild TBI in rodents, studying the effects of multiple hits has been complicated by the need for multiple survival surgeries, extensive pre-injury anesthesia time, and limitations due to animal skull thickness.•We developed a chronic "helmet" implant by combining aspects of the Impact Acceleration and Controlled Cortical Impact models.•Implants were performed days before injury, allowing us to decouple surgery from TBI. Critically, by pre-implanting the animals, only minimal anesthesia was required to position them under the impactor.•The implant allows for flexibility in the number and severity of injuries and interval between impacts.

A new model of repeat mTBI in adolescent rats

Sports-related injury is frequently associated with repeated diffuse and mild traumatic brain injury (mTBI). We combined two existing models for inducing TBI in rats, the Impact Acceleration and Controlled Cortical Impact models, to create a new method relevant to the study of cognitive sequelae of repeat mTBI in adolescent athletes. Repeated mTBI, such as those incurred in sports, can result in a wide range of outcomes, with many individuals experiencing no chronic sequela while others develop profound cognitive and behavioral impairments, typically in the absence of lasting motor symptoms or gross tissue loss appreciable antemortem. It is critical to develop models of mTBI and repeat mTBI that have the flexibility to assess multiple parameters related to injury (e.g. number and magnitude of impacts, inter-injury interval, etc) that are associated with brain vulnerability compared to normal recovery. We designed a 3D-printed plastic implant to permanently secure a metal disc to the skull of adolescent rats in order to induce multiple injuries without performing multiple survival surgeries and also to minimize pre-injury anesthesia time. Rats were randomly assigned to sham injury (n = 12), single injury (n = 12; injury on P41), or repeat injury (n = 14; injuries on P35, P38, and P41) groups. Compared to single injury and sham injury, repeat injuries caused increased toe pinch reflex latency (F(2,34) = 4.126, p < .05) and diminished weight gain (F(2, 34) = 4.767, p < .05). Spatial navigation was tested using Morris water maze, beginning one week after the final injury (P48). While there were no differences between groups during acquisition, both single and repeat injuries resulted in deficits on probe trial performance (p < .01 and p < .05 respectively). Single injury animals also exhibited a deficit in working memory deficit across three days of testing (p < .05). Neither injury group had neuronal loss in the hilus or CA3, according to stereological quantification of NeuN. Therefore, by implanting a helmet we have created a relevant model of sports-related injury and repeated mTBI that results in subtle but significant changes in cognitive outcome in the absence of significant hippocampal cell death.

Clinically indicated electrical stimulation strategies to treat patients with medically refractory epilepsy

Focal epilepsies represent approximately half of all diagnoses, and more than one-third of these patients are refractory to pharmacologic treatment. Although resection can result in seizure freedom, many patients do not meet surgical criteria, as seizures may be multifocal in origin or have a focus in an eloquent region of the brain. For these individuals, several U.S. Food and Drug Administration (FDA)-approved electrical stimulation paradigms serve as alternative options, including vagus nerve stimulation, responsive neurostimulation, and stimulation of the anterior nucleus of the thalamus. All of these are safe, flexible, and lead to progressive seizure control over time when used as an adjunctive therapy to antiepileptic drugs. Focal epilepsies frequently involve significant comorbidities such as cognitive decline. Similar to antiepilepsy medications and surgical resection, current stimulation targets and parameters have yet to address cognitive impairments directly, with patients reporting persistent comorbidities associated with focal epilepsy despite a significant reduction in the number of their seizures. Although low-frequency theta oscillations of the septohippocampal network are critical for modulating cellular activity and, in turn, cognitive processing, the coordination of neural excitability is also imperative for preventing seizures. In this review, we summarize current FDA-approved electrical stimulation paradigms and propose that theta oscillations of the medial septal nucleus represent a novel neuromodulation target for concurrent seizure reduction and cognitive improvement in epilepsy. Ultimately, further advancements in clinical neurostimulation strategies will allow for the efficient treatment of both seizures and comorbidities, thereby improving overall quality of life for patients with epilepsy.

Impairments in precision, rather than spatial strategy, characterize performance on the virtual Morris Water Maze: A case study

Damage to the medial temporal lobes produces profound amnesia, greatly impairing the ability of patients to learn about new associations and events. While studies in rodents suggest a strong link between damage to the hippocampus and the ability to navigate using distal landmarks in a spatial environment, the connection between navigation and memory in humans remains less clear. Past studies on human navigation have provided mixed findings about whether patients with damage to the medial temporal lobes can successfully acquire and navigate new spatial environments, possibly due, in part, to issues related to patient demographics and characterization of medial temporal lobe damage. Here, we report findings from a young, high functioning patient who suffered severe medial temporal lobe damage. Although the patient is densely amnestic, her ability to acquire and utilize new, but coarse, spatial "maps" appears largely intact. Specifically, a novel computational analysis focused on the precision of her spatial search revealed a significant deficit in spatial precision rather than spatial search strategy. These findings argue that an intact hippocampus in humans is not necessary for representing multiple external landmarks during spatial navigation of new environments. We suggest instead that the human hippocampus may store and represent complex high-resolution bindings of features in the environment as part of a larger role in perception, memory, and navigation.

Voltage-gated calcium channel antagonists and traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability in the United States. Despite more than 30 years of research, no pharmacological agents have been identified that improve neurological function following TBI. However, several lines of research described in this review provide support for further development of voltage gated calcium channel (VGCC) antagonists as potential therapeutic agents. Following TBI, neurons and astrocytes experience a rapid and sometimes enduring increase in intracellular calcium ([Ca²⁺]_i). These fluxes in [Ca²⁺]_i drive not only apoptotic and necrotic cell death, but also can lead to long-term cell dysfunction in surviving cells. In a limited number of in vitro experiments, both L-type and N-type VGCC antagonists successfully reduced calcium loads as well as neuronal and astrocytic cell death following mechanical injury. In rodent models of TBI, administration of VGCC antagonists reduced cell death and improved cognitive function. It is clear that there is a critical need to find effective therapeutics and rational drug delivery strategies for the management and treatment of TBI, and we believe that further investigation of VGCC antagonists should be pursued before ruling out the possibility of successful translation to the clinic.