DREDge: robust motion correction for high-density extracellular recordings across species.

High-density microelectrode arrays (MEAs) have opened new possibilities for systems neuroscience in human and non-human animals, but brain tissue motion relative to the array poses a challenge for downstream analyses, particularly in human recordings. We introduce DREDge (Decentralized Registration of Electrophysiology Data), a robust algorithm which is well suited for the registration of noisy, nonstationary extracellular electrophysiology recordings. In addition to estimating motion from spikes in the action potential (AP) frequency band, DREDge enables automated tracking of motion at high temporal resolution in the local field potential (LFP) frequency band. In human intraoperative recordings, which often feature fast (period <1s) motion, DREDge correction in the LFP band enabled reliable recovery of evoked potentials, and significantly reduced single-unit spike shape variability and spike sorting error. Applying DREDge to recordings made during deep probe insertions in nonhuman primates demonstrated the possibility of tracking probe motion of centimeters across several brain regions while simultaneously mapping single unit electrophysiological features. DREDge reliably delivered improved motion correction in acute mouse recordings, especially in those made with an recent ultra-high density probe. We also implemented a procedure for applying DREDge to recordings made across tens of days in chronic implantations in mice, reliably yielding stable motion tracking despite changes in neural activity across experimental sessions. Together, these advances enable automated, scalable registration of electrophysiological data across multiple species, probe types, and drift cases, providing a stable foundation for downstream scientific analyses of these rich datasets.

Co-transplantation of autologous Treg cells in a cell therapy for Parkinson's disease.

The specific loss of midbrain dopamine neurons (mDANs) causes major motor dysfunction in Parkinson's disease, which makes cell replacement a promising therapeutic approach1-4. However, poor survival of grafted mDANs remains an obstacle to successful clinical outcomes5-8. Here we show that the surgical procedure itself (referred to here as 'needle trauma') triggers a profound host response that is characterized by acute neuroinflammation, robust infiltration of peripheral immune cells and brain cell death. When midbrain dopamine (mDA) cells derived from human induced pluripotent stem (iPS) cells were transplanted into the rodent striatum, less than 10% of implanted tyrosine hydroxylase (TH)+ mDANs survived at two weeks after transplantation. By contrast, TH- grafted cells mostly survived. Notably, transplantation of autologous regulatory T (Treg) cells greatly modified the response to needle trauma, suppressing acute neuroinflammation and immune cell infiltration. Furthermore, intra-striatal co-transplantation of Treg cells and human-iPS-cell-derived mDA cells significantly protected grafted mDANs from needle-trauma-associated death and improved therapeutic outcomes in rodent models of Parkinson's disease with 6-hydroxydopamine lesions. Co-transplantation with Treg cells also suppressed the undesirable proliferation of TH- grafted cells, resulting in more compact grafts with a higher proportion and higher absolute numbers of TH+ neurons. Together, these data emphasize the importance of the initial inflammatory response to surgical injury in the differential survival of cellular components of the graft, and suggest that co-transplanting autologous Treg cells effectively reduces the needle-trauma-induced death of mDANs, providing a potential strategy to achieve better clinical outcomes for cell therapy in Parkinson's disease.

Clinical considerations in Parkinson's disease cell therapy.

Cell replacement therapy is an area of increasing interest for treating Parkinson's disease (PD). However, to become a clinically practical option for PD patients, it must first overcome significant barriers, including establishment of safe and standardized surgical procedures, determination of appropriate perioperative medication regimens, demonstration of long-term graft survival and incorporation, and standardized, clinically meaningful follow-up measures. In this review, we will describe the current status of cell therapy for PD with special attention to these critical requirements, to define guideposts on the road to bring the benefit of this therapy to the Parkinson's clinic.

Panning for gold: Purifying mesencephalic dopaminergic progenitors differentiated from human pluripotent stem cells.

In a recently published study, Xu et al. used two surface markers, CLSTN2 and PTPRO, to generate highly purified donor dopaminergic neurons and achieved stable and predictable therapeutic outcomes by transplantation into the brain of PD animal models (Xu et al., 2022).

A Pitx3-deficient developmental mouse model for fine motor, olfactory, and gastrointestinal symptoms of Parkinson's disease.

Parkinson's disease (PD) is characterized by the selective death of substantia nigra pars compacta (SNpc) dopaminergic neurons and includes both motor and non-motor symptoms. While numerous models exist for the study of typical PD motor deficits, fewer exist for non-motor symptoms. Previous studies have shown that a Pitx3-/- mouse model (aphakia or ak mouse) has specific developmental failure of the dopaminergic neuron population in the SNpc and that it can be used for the study of PD-related gross motor dysfunction as well as cognitive functional deficits. It remains unclear whether the aphakia mouse, both male and female, might also be used to model fine motor deficits and for additional studies of non-motor deficits associated with PD. Here, using an extensive battery of behavioral tests, we demonstrate that the aphakia mouse shows both gross and fine motor functional deficits compared with control mice. Furthermore, aphakia mice show deficits of olfactory function in buried pellet, odor discrimination and odor habituation/dishabituation tests. We also found that aphakia mice suffer from gastrointestinal dysfunction (e.g., longer whole gut transit time and colon motility deficits), suggesting that the mutation also affects function of the gut-brain axis in this animal model. Moreover, our data demonstrate that in the aphakia mouse, L-DOPA, the gold standard PD medication, can rescue both gross and fine motor function deficits but neither olfactory nor gastrointestinal symptoms, a pattern much like that seen in PD patients. Altogether, this suggests that the aphakia mouse is a suitable model for fine motor, olfactory and gastrointestinal behavioral studies of PD as well as for the development of novel disease-modifying therapeutics. SIGNIFICANCE STATEMENT: While several animal models are available to study the major motor symptoms of PD, there are fewer that replicate non-motor symptoms, which constitute a major source of morbidity for patients. Moreover, available models often require manipulations resulting in sudden massive cell loss and inflammation, both of which may interfere with understanding of the direct effects of dopaminergic neuronal loss in the SNpc. We describe a model of congenital SNpc cell deficiency in a Pitx3-/- mouse and characterize it with a battery of behavioral tests suggesting that it closely mimics non-motor as well as motor symptoms of PD, providing a useful insight into the effects of the nigrostriatal dopamine deficit. Taken together, these data suggest that the ak mouse represents a useful model to study dopaminergic system function for both motor and non-motor symptoms of PD.

Cortical Spreading Depolarizations and Clinically Measured Scalp EEG Activity After Aneurysmal Subarachnoid Hemorrhage and Traumatic Brain Injury.

BACKGROUND: Spreading depolarizations (SDs) are associated with worse outcome following subarachnoid hemorrhage (SAH) and traumatic brain injury (TBI), but gold standard detection requires electrocorticography with a subdural strip electrode. Electroencephalography (EEG) ictal-interictal continuum abnormalities are associated with poor outcomes after TBI and with both delayed cerebral ischemia (DCI) and poor outcomes after SAH. We examined rates of SD detection in patients with SAH and TBI with intraparenchymal and subdural strip electrodes and assessed which continuous EEG (cEEG) measures were associated with intracranially quantified SDs. METHODS: In this single-center cohort, we included patients with SAH and TBI undergoing ≥ 24 h of interpretable intracranial monitoring via eight-contact intraparenchymal or six-contact subdural strip platinum electrodes or both. SDs were rated according to established consensus criteria and compared with cEEG findings rated according to the American Clinical Neurophysiology Society critical care EEG monitoring consensus criteria: lateralized rhythmic delta activity, generalized rhythmic delta activity, lateralized periodic discharges, generalized periodic discharges, any ictal-interictal continuum, or a composite scalp EEG tool for seizure risk estimation: the 2HELPS2B score. Among patients with SAH, cEEG was assessed for validated DCI biomarkers: new or worsening epileptiform abnormalities and new background deterioration. RESULTS: Over 6 years, SDs were recorded in 5 (18%) of 28 patients recorded with intraparenchymal electrodes and 4 (40%) of 10 patients recorded with subdural strip electrodes. There was no significant association between occurrence of SDs and day 1 cEEG findings (American Clinical Neurophysiology Society main terms lateralized periodic discharges, generalized periodic discharges, lateralized rhythmic delta activity, or seizures, individually or in combination). After SAH, established cEEG DCI predictors were not associated with SDs. CONCLUSIONS: Intraparenchymal recordings yielded low rates of SD, and documented SDs were not associated with ictal-interictal continuum abnormalities or other cEEG DCI predictors. Identifying scalp EEG correlates of SD may require training computational EEG analytics and use of gold standard subdural strip electrocorticography recordings.

A step closer to autologous cell therapy for Parkinson's disease.

In a recent report in Nature Medicine, Tao et al. (2021) demonstrate that MPTP-treated monkeys receiving autologous, but not allogeneic, transplantation showed significant long-term improvement in motor and depressive behaviors, supporting the feasibility of autologous cell therapy for Parkinson's disease (PD).

Personalized iPSC-Derived Dopamine Progenitor Cells for Parkinson's Disease.

We report the implantation of patient-derived midbrain dopaminergic progenitor cells, differentiated in vitro from autologous induced pluripotent stem cells (iPSCs), in a patient with idiopathic Parkinson's disease. The patient-specific progenitor cells were produced under Good Manufacturing Practice conditions and characterized as having the phenotypic properties of substantia nigra pars compacta neurons; testing in a humanized mouse model (involving peripheral-blood mononuclear cells) indicated an absence of immunogenicity to these cells. The cells were implanted into the putamen (left hemisphere followed by right hemisphere, 6 months apart) of a patient with Parkinson's disease, without the need for immunosuppression. Positron-emission tomography with the use of fluorine-18-L-dihydroxyphenylalanine suggested graft survival. Clinical measures of symptoms of Parkinson's disease after surgery stabilized or improved at 18 to 24 months after implantation. (Funded by the National Institutes of Health and others.).

Columnar Injection for Intracerebral Cell Therapy.

BACKGROUND: Surgical implantation of cellular grafts into the brain is of increasing importance, as stem cell-based therapies for Parkinson and other diseases continue to develop. The effect of grafting technique on development and survival of the graft has received less attention. Rate and method of graft delivery may impact the cell viability and success of these therapies. Understanding the final location of the graft with respect to the intended target location is also critical. OBJECTIVE: To describe a "columnar injection" technique designed to reduce damage to host tissue and result in a column of graft material with greater surface area to volume ratio than traditional injection techniques. METHODS: Using a clinically relevant model system of human embryonic stem cell-derived dopaminergic progenitors injected into athymic rat host brain, we describe a novel device that allows separate control of syringe barrel and plunger, permitting precise deposition of the contents into the cannula tract during withdrawal. Controls consist of contralateral injection using traditional techniques. Graft histology was examined at graft maturity. RESULTS: Bolus grafts were centered on the injection tract but were largely proximal to the "target" location. These grafts displayed a conspicuous peripheral distribution of cells, particularly of mature dopaminergic neurons. In contrast, column injections remained centered at the intended target, contained more evenly distributed cells, and had significantly more mature dopaminergic neurons. CONCLUSION: We suggest that this columnar injection technique may allow better engraftment and development of intracerebral grafts, enhancing outcomes of cell therapy, compared to fixed-point injection techniques.

Human autologous iPSC-derived dopaminergic progenitors restore motor function in Parkinson's disease models.

Parkinson's disease (PD) is a neurodegenerative disorder associated with loss of striatal dopamine, secondary to degeneration of midbrain dopamine (mDA) neurons in the substantia nigra, rendering cell transplantation a promising therapeutic strategy. To establish human induced pluripotent stem cell-based (hiPSC-based) autologous cell therapy, we report a platform of core techniques for the production of mDA progenitors as a safe and effective therapeutic product. First, by combining metabolism-regulating microRNAs with reprogramming factors, we developed a method to more efficiently generate clinical-grade iPSCs, as evidenced by genomic integrity and unbiased pluripotent potential. Second, we established a "spotting"-based in vitro differentiation methodology to generate functional and healthy mDA cells in a scalable manner. Third, we developed a chemical method that safely eliminates undifferentiated cells from the final product. Dopaminergic cells thus express high levels of characteristic mDA markers, produce and secrete dopamine, and exhibit electrophysiological features typical of mDA cells. Transplantation of these cells into rodent models of PD robustly restores motor function and reinnervates host brain, while showing no evidence of tumor formation or redistribution of the implanted cells. We propose that this platform is suitable for the successful implementation of human personalized autologous cell therapy for PD.

Successful placement of intracranial pressure monitors by trauma surgeons.

BACKGROUND: The Brain Trauma Foundation guidelines advocate for the use of intracranial pressure (ICP) monitoring following traumatic brain injury (TBI) in patients with a Glasgow Coma Scale (GCS) score of 8 or less and an abnormal computed tomographic scan finding. The absence of 24-hour in-house neurosurgery coverage can negatively impact timely monitor placement. We reviewed the safety profile of ICP monitor placement by trauma surgeons trained and credentialed in their insertion by neurosurgeons. METHODS: In 2005, the in-house trauma surgeons at a Level I trauma center were trained and credentialed in the placement of ICP parenchymal monitors by the neurosurgeons. We abstracted all TBI patients who had ICP monitors placed during a 6-year period. Demographic information, Injury Severity Score (ISS), outcome, and monitor placement by neurosurgery or trauma surgery were identified. Misplacement, hemorrhage, infections, malfunctions, and dislodgement were considered complications. Comparisons were performed by χ testing and Student's t tests. RESULTS: During the 6-year period, 410 ICP monitors were placed for TBI. The mean (SD) patient age was 40.9 (18.9) years, 73.7% were male, mean (SD) ISS was 28.3 (9.4), mean (SD) length of stay was 19 (16) days, and mortality was 36.1%. Motor vehicle collisions and falls were the most common mechanisms of injury (35.2% and 28.7%, respectively). The trauma surgeons placed 71.7 % of the ICP monitors and neurosurgeons for the remainder. The neurosurgeons placed most of their ICP monitors (71.8%) in the operating room during craniotomy. The overall complication rate was 2.4%. There was no significant difference in complications between the trauma surgeons and neurosurgeons (3% vs. 0.8%, p = 0.2951). CONCLUSION: After appropriate training, ICP monitors can be safely placed by trauma surgeons with minimal adverse effects. With current and expected specialty shortages, acute care surgeons can successfully adopt procedures such as ICP monitor placement with minimal complications. LEVEL OF EVIDENCE: Therapeutic/care management study, level IV.

Increased expression of erythropoietin receptor on blood vessels in the human epileptogenic hippocampus with sclerosis.

Microvascular (capillary) proliferation is a readily observed, but largely ignored phenomenon of the mesial temporal lobe epilepsy (MTLE) hippocampus. Here, we report that the proliferated capillaries in surgically resected MTLE hippocampi were strongly immunoreactive for erythropoietin receptor (EPO-r). Further, we found that these capillaries were most prominent in areas of the MTLE hippocampus with extensive neuronal loss and gliosis, i.e. the CA3, CA1, and dentate hilus. High-resolution immunogold electron microscopy revealed that the capillary EPO-r was localized to the luminal and abluminal plasma membrane of endothelial cells, to endosome-like structures of these cells, and to pericapillary astrocytic end-feet. Previous studies have shown that systemically administered EPO appears in the cerebrospinal fluid in experimental animals, and the present results are consistent with the idea that EPO enters the brain via receptor-mediated endocytosis. The enrichment of EPO-r shown here suggests a highly efficient uptake of plasma EPO into the MTLE hippocampus and a possible role for this cytokine in epileptogenesis. Moreover, the presence of EPO-r in the MTLE hippocampus may provide a new vehicle for highly efficient delivery of hitherto impermeable drugs into the epileptic brain.