Arjun V. Pendharkar

Biodistribution of Neural Stem Cells After Intravascular Therapy for Hypoxic–Ischemia

Background and Purpose— Intravascular transplantation of neural stem cells represents a minimally invasive therapeutic approach for the treatment of central nervous system diseases. The cellular biodistribution after intravascular injection needs to be analyzed to determine the ideal delivery modality. We studied the biodistribution and efficiency of targeted central nervous system delivery comparing intravenous and intra-arterial (IA) administration of neural stem cells after brain ischemia. Methods— Mouse neural stem cells were transduced with a firefly luciferase reporter gene for bioluminescence imaging (BLI). Hypoxic–ischemia was induced in adult mice and reporter neural stem cells were transplanted IA or intravenous at 24 hours after brain ischemia. In vivo BLI was used to track transplanted cells up to 2 weeks after transplantation and ex vivo BLI was used to determine single organ biodistribution. Results— Immediately after transplantation, BLI signal from the brain was 12 times higher in IA versus intravenous injected animals (P<0.0001). After IA injection, 69% of the total luciferase activity arose from the brain early after transplantation and 93% at 1 week. After intravenous injection, 94% of the BLI signal was detected in the lungs (P=0.004) followed by an overall 94% signal loss at 1 week, indicating lack of cell survival outside the brain. Ex vivo single organ analysis showed a significantly higher BLI signal in the brain than in the lungs, liver, and kidneys at 1 week (P<0.0001) and 2 weeks in IA (P=0.007). Conclusion— IA transplantation results in superior delivery and sustained presence of neural stem cells in the ischemic brain in comparison to intravenous infusion.

The CCR2/CCL2 Interaction Mediates the Transendothelial Recruitment of Intravascularly Delivered Neural Stem Cells to the Ischemic Brain

Background and Purpose— The inflammatory response is a critical component of ischemic stroke. In addition to its physiological role, the mechanisms behind transendothelial recruitment of immune cells also offer a unique therapeutic opportunity for translational stem cell therapies. Recent reports have demonstrated homing of neural stem cells (NSC) into the injured brain areas after intravascular delivery. However, the mechanisms underlying the process of transendothelial recruitment remain largely unknown. Here we describe the critical role of the chemokine CCL2 and its receptor CCR2 in targeted homing of NSC after ischemia. Methods— Twenty-four hours after induction of stroke using the hypoxia-ischemia model in mice CCR2+/+ and CCR2−/− reporter NSC were intra-arterially delivered. Histology and bioluminescence imaging were used to investigate NSC homing to the ischemic brain. Functional outcome was assessed with the horizontal ladder test. Results— Using NSC isolated from CCR2+/+ and CCR2−/− mice, we show that receptor deficiency significantly impaired transendothelial diapedesis specifically in response to CCL2. Accordingly, wild-type NSC injected into CCL2−/− mice exhibited significantly decreased homing. Bioluminescence imaging showed robust recruitment of CCR2+/+ cells within 6 hours after transplantation in contrast to CCR2−/− cells. Mice receiving CCR2+/+ grafts after ischemic injury showed a significantly improved recovery of neurological deficits as compared to animals with transplantation of CCR2−/− NSC. Conclusions— The CCL2/CCR2 interaction is critical for transendothelial recruitment of intravascularly delivered NSC in response to ischemic injury. This finding could have significant implications in advancing minimally invasive intravascular therapeutics for regenerative medicine or cell-based drug delivery systems for central nervous system diseases.

Intra-Arterial Injection of Neural Stem Cells using a Microneedle Technique does not Cause Microembolic Strokes

Intra-arterial (IA) injection represents an experimental avenue for minimally invasive delivery of stem cells to the injured brain. It has however been reported that IA injection of stem cells carries the risk of reduction in cerebral blood flow (CBF) and microstrokes. Here we evaluate the safety of IA neural progenitor cell (NPC) delivery to the brain. Cerebral blood flow of rats was monitored during IA injection of single cell suspensions of NPCs after stroke. Animals received 1×106 NPCs either injected via a microneedle (microneedle group) into the patent common carotid artery (CCA) or via a catheter into the proximally ligated CCA (catheter group). Controls included saline-only injections and cell injections into non-stroked sham animals. Cerebral blood flow in the microneedle group remained at baseline, whereas in the catheter group a persistent (15 minutes) decrease to 78% of baseline occurred (P < 0.001). In non-stroked controls, NPCs injected via the catheter method resulted in higher levels of Iba-1-positive inflammatory cells (P = 0.003), higher numbers of degenerating neurons as seen in Fluoro-Jade C staining (P < 0.0001) and ischemic changes on diffusion weighted imaging. With an appropriate technique, reduction in CBF and microstrokes do not occur with IA transplantation of NPCs.

Timing of Intra-Arterial Neural Stem Cell Transplantation After Hypoxia–Ischemia Influences Cell Engraftment, Survival, and Differentiation

Background and Purpose— Intra-arterial neural stem cell (NSC) transplantation shows promise as a minimally invasive therapeutic option for stroke. We assessed the effect of timing of transplantation on cell engraftment, survival, and differentiation. Methods— Mouse NSCs transduced with a green fluorescent protein and renilla luciferase reporter gene were transplanted into animals 6 and 24 hours and 3, 7, and 14 days after hypoxia–ischemia (HI). Bioluminescent imaging was used to assess cell survival at 6 hours and 4 and 7 days after transplantation. Immunohistochemistry was used to assess NSC survival and phenotypic differentiation 1 month after transplantation. NSC receptor expression and brain gene expression were evaluated using real-time reverse transcription–quantitative polymerase chain reaction to elucidate mechanisms of cell migration. Boyden chamber assays were used to assess cell migratory potential in vitro. Results— NSC transplantation 3 days after HI resulted in significantly higher cell engraftment and survival at 7 and 30 days compared with all other groups (P<0.05). Early transplantation at 6 and 24 hours after HI resulted in significantly higher expression of glial fibrillary acidic protein (P=0.0140), whereas late transplantation at 7 and 14 days after HI resulted in higher expression of &bgr;-tubulin (P<0.0001). Corroborating the high cell engraftment 3 days after HI was robust expression of vascular cell adhesion molecule-1, CCL2, and CXCL12 in brain homogenates 3 days after HI. Conclusion— Intra-arterial transplantation 3 days after HI results in the highest cell engraftment. Early transplantation of NSCs leads to greater differentiation into astrocytes, whereas transplantation at later time points leads to greater differentiation into neurons.

Clinical evaluation of concussion: the evolving role of oculomotor assessments.

Sports-related concussion is a change in brain function following a direct or an indirect force to the head, identified in awake individuals and accounting for a considerable proportion of mild traumatic brain injury. Although the neurological signs and symptoms of concussion can be subtle and transient, there can be persistent sequelae, such as impaired attention and balance, that make affected patients particularly vulnerable to further injury. Currently, there is no accepted definition or diagnostic criteria for concussion, and there is no single assessment that is accepted as capable of identifying all patients with concussion. In this paper, the authors review the available screening tools for concussion, with particular emphasis on the role of visual function testing. In particular, they discuss the oculomotor assessment tools that are being investigated in the setting of concussion screening.

Deep Brain Stimulation for Obesity

Obesity is now the third leading cause of preventable death in the US, accounting for 216,000 deaths annually and nearly 100 billion dollars in health care costs. Despite advancements in bariatric surgery, substantial weight regain and recurrence of the associated metabolic syndrome still occurs in almost 20-35% of patients over the long-term, necessitating the development of novel therapies. Our continually expanding knowledge of the neuroanatomic and neuropsychiatric underpinnings of obesity has led to increased interest in neuromodulation as a new treatment for obesity refractory to current medical, behavioral, and surgical therapies. Recent clinical trials of deep brain stimulation (DBS) in chronic cluster headache, Alzheimer’s disease, and depression and obsessive-compulsive disorder have demonstrated the safety and efficacy of targeting the hypothalamus and reward circuitry of the brain with electrical stimulation, and thus provide the basis for a neuromodulatory approach to treatment-refractory obesity. In this study, we review the literature implicating these targets for DBS in the neural circuitry of obesity. We will also briefly review ethical considerations for such an intervention, and discuss genetic secondary-obesity syndromes that may also benefit from DBS. In short, we hope to provide the scientific foundation to justify trials of DBS for the treatment of obesity targeting these specific regions of the brain.

Successful treatment of severe cerebral vasospasm following hemorrhage of an arteriovenous malformation. Case report.

The authors describe the case of a 13-year-old boy who presented with an intraventricular hemorrhage caused by a left trigonal arteriovenous malformation. After an initial recovery, the patient experienced complete right-sided paresis on posthemorrhage Day 6. Severe cerebral vasospasm was found on MR angiography and confirmed on conventional cerebral angiography. Intraarterial nicardipine injection and balloon angioplasty were successfully performed with improved vasospasm and subsequent neurological recovery. Cerebral vasospasm should be considered in the differential diagnosis for neurological deterioration following an arteriovenous malformation hemorrhage, and aggressive treatment can be administered to prevent ischemia and further neurological deficits.

Cushing's disease: predicting long-term remission after surgical treatment

Cushings disease (CD) is a state of excess glucocorticoid production resulting from an adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma. The gold-standard treatment for CD is transsphenoidal adenomectomy. In the hands of an experienced neurosurgeon, gross-total resection is possible in the majority of ACTH-secreting pituitary adenomas, with early postoperative remission rates ranging from 67% to 95%. In contrast to the strong data in support of resection, the clinical course of postsurgical persistent or recurrent disease remains unclear. There is significant variability in recurrence rates, with reports as high as 36% with a mean time to recurrence of 15-50 months. It is therefore important to develop biochemical criteria that define postsurgical remission and that may provide prognosis for long-term recurrence. Despite the use of a number of biochemical assessments, there is debate regarding the accuracy of these tests in predicting recurrence. Here, the authors review the various biochemical criteria and assess their utility in predicting CD recurrence after resection.

Junior Seau: An Illustrative Case of Chronic Traumatic Encephalopathy and Update on Chronic Sports-Related Head Injury

BACKGROUND Few neurologic diseases have captured the nations attention more completely than chronic traumatic encephalopathy (CTE), which has been discovered in the autopsies of professional athletes, most notably professional football players. The tragic case of Junior Seau, a Hall of Fame, National Football League linebacker, has been the most high-profile confirmed case of CTE. Here we describe Seaus case, which concludes an autopsy conducted at the National Institutes of Health that confirmed the diagnosis. CASE DESCRIPTION Since 1990, Junior Seau had a highly distinguished 20-year career playing for the National Football League as a linebacker, from which he sustained multiple concussions. He committed suicide on May 2, 2012, at age 43, after which an autopsy confirmed a diagnosis of CTE. His clinical history was significant for a series of behavioral disturbances. Seaus history and neuropathologic findings were used to better understand the pathophysiology, diagnosis, and possible risk factors for CTE. CONCLUSIONS This high-profile case reflects an increasing awareness of CTE as a long-term consequence of multiple traumatic brain injuries. The previously unforeseen neurologic risks of American football have begun to cast doubt on the safety of the sport.

Endoscopic Transnasal Approach for Urgent Decompression of the Craniocervical Junction in Acute Skull Base Osteomyelitis.

Ventral epidural abscess with osteomyelitis at the craniocervical junction is a rare occurrence that typically mandates spinal cord decompression via a transoral approach. However, given the potential for morbidity with transoral surgery, especially in the setting of immunosuppression, together with the advent of extended endonasal techniques, the transnasal approach could be attractive for selected patients. We present two cases of ventral epidural abscess and osteomyelitis at the craniocervical junction involving C1/C2 that were successfully treated via the endoscopic transnasal approach. Both were treated in staged procedures involving posterior cervical fusion followed by endoscopic transnasal resection of the ventral C1 arch and odontoid process for decompression of the ventral spinal cord and medulla. Dural repairs were successfully performed using multilayered, onlay techniques where required. Both patients tolerated surgery exceedingly well, had brief postoperative hospital stays, and recovered uneventfully to their neurologic baselines. Postoperative magnetic resonance imaging confirmed complete decompression of the foramen magnum and upper C-spine. These cases illustrate the advantages and low morbidity of the endonasal endoscopic approach to the craniocervical junction in the setting of frank skull base infection and immunosuppression, representing to our knowledge a unique application of this technique to osteomyelitis and epidural abscess at the craniocervical junction.