Label-free enrichment of fate-biased human neural stem and progenitor cells.

Human neural stem and progenitor cells (hNSPCs) have therapeutic potential to treat neural diseases and injuries since they provide neuroprotection and differentiate into astrocytes, neurons, and oligodendrocytes. However, cultures of hNSPCs are heterogeneous, containing cells linked to distinct differentiated cell fates. HNSPCs that differentiate into astrocytes are of interest for specific neurological diseases, creating a need for approaches that can detect and isolate these cells. Astrocyte-biased hNSPCs differ from other cell types in electrophysiological properties, namely membrane capacitance, and we hypothesized that this could be used to enrich these cells using dielectrophoresis (DEP). We implemented a two-step DEP sorting scheme, consisting of analysis to define the optimal sorting frequency followed by separation of cells at that frequency, to test whether astrocyte-biased cells could be separated from the other cell types present in hNSPC cultures. We developed a novel device that increased sorting reproducibility and provided both enriched and depleted cell populations in a single sort. Astrocyte-biased cells were successfully enriched from hNSPC cultures by DEP sorting, making this the first study to use electrophysiological properties for label-free enrichment of human astrocyte-biased cells. Enriched astrocyte-biased human cells enable future experiments to determine the specific properties of these important cells and test their therapeutic efficacy in animal models of neurological diseases.

Identification of neural stem and progenitor cell subpopulations using DC insulator-based dielectrophoresis.

Neural stem and progenitor cells (NSPCs) are an extremely important group of cells that form the central nervous system during development and have the potential to repair damage in conditions such as stroke impairment, spinal cord injury and Parkinson's disease degradation. Current schemes for separation of NSPCs are inadequate due to the complexity and diversity of cells in the population and lack sufficient markers to distinguish diverse cell types. This study presents an unbiased high-resolution separation and characterization of NSPC subpopulations using direct current insulator-based dielectrophoresis (DC-iDEP). The properties of the cells were identified by the ratio of electrokinetic (EK) to dielectrophoretic (DEP) mobilities. The ratio factor of NSPCs showed more heterogeneity variance (SD = 3.4-3.9) than the controlled more homogeneous human embryonic kidney cells (SD = 1.1), supporting the presence of distinct subpopulations of cells in NSPC cultures. This measure reflected NSPC fate potential since the ratio factor distribution of more neurogenic populations of NSPCs was distinct from the distribution of astrogenic NSPC populations (confidence level >99.9%). The abundance of NSPCs captured with different ranges of ratio of EK to DEP mobilities also exhibit final fate trends consistent with established final fates of the chosen samples. DC-iDEP is a novel, label-free and non-destructive method for differentiating and characterizing, and potentially separating, neural stem cell subpopulations that differ in fate.

Financial implications of telemedicine visits in an academic endocrine surgery program.

BACKGROUND: Telemedicine is an emerging medium for the delivery of ambulatory care, but the reimbursement profile of telemedicine visits in the surgical setting has not been well studied. METHODS: A retrospective assessment of telemedicine encounters for thyroid and parathyroid conditions occurring from April 2015 to April 2017 was performed. Financial reimbursement from commercial payers for new and established patient visits were compared between telemedicine visits and in-person visits. Patient "savings" in terms of travel distance and drive time were calculated. RESULTS: A total of 290 telemedicine encounters were conducted; 7% were initial consultations, 47% were postoperative visits, and 45% were follow-up visits. The median patient age was 57 years. The median round-trip travel distance saved was 123.6 miles with estimated drive time of 2.4 hours per encounter. In 2% of cases, a second in-person visit within the 90-day global period occurred after a postoperative telemedicine encounter. Charges were filed for 67 encounters. The initial unpaid claims rate was 6%, which was consistent with the unpaid claims rate for in-person visits. The charge-to-collection ratio was comparable to that of in-person visits. There was a higher ratio of level 2 visits in the telemedicine encounters. Over the study period, 70 clinic hours were liberated via the use of telemedicine. CONCLUSION: Endocrine surgery telemedicine visits have the same level for level reimbursement profile as in-person visits. Down-coding and elimination of components of in-office physical examinations may lead to modest decreases in overall reimbursement. Other advantages include reallocation of clinic resources and decreased travel burden for patients.

Impact of Hypothyroidism and Heart Failure on Hospitalization Risk.

BACKGROUND: Prior studies suggest that the relationship between hypothyroidism and mortality is dependent on underlying cardiovascular risk. Little is known about the association of hypothyroidism with hospitalization risk, and how these associations are modified by cardiovascular status. METHODS: This study examined the association of thyroid status, defined by serum thyrotropin (TSH), with hospitalization risk among patients who received care at a large university-based tertiary care center between 1990 and 2015. Thyroid status was categorized as hypothyroidism versus euthyroidism (TSH >4.7 vs. 0.3-4.7 mIU/L, respectively). The relationship between thyroid status and hospitalization risk stratified by cardiovascular status was examined using multivariable Cox models. RESULTS: Among 52,856 patients who met eligibility criteria, 49,791 (94.2%) had euthyroidism and 3065 (5.8%) had hypothyroidism. In analyses stratified by congestive heart failure (CHF) status, compared to euthyroidism, hypothyroidism was associated with higher risk of hospitalization in those with CHF but slightly lower risk in those without CHF (adjusted hazard ratio [aHRs] = 1.86 [confidence interval (CI) 1.17-2.94] and HR = 0.95 [CI 0.92-0.99], respectively; p = 0.006). In sensitivity analyses accounting for death as a competing event, underlying coronary artery disease modified the hypothyroidism-hospitalization relationship, such that stronger associations were observed among those with versus without coronary artery disease. In competing risk analyses, hypothyroidism was associated with higher versus lower risk of hospitalization among those with versus without cerebrovascular disease, respectively. CONCLUSIONS: Hypothyroidism is associated with higher hospitalization risk among patients with underlying cardiovascular disease. Future studies are needed to determine whether correction of thyroid status with replacement therapy ameliorates hospitalization risk in this population.

Phagocytic response of astrocytes to damaged neighboring cells.

This study aims to understand the phagocytic response of astrocytes to the injury of neurons or other astrocytes at the single cell level. Laser nanosurgery was used to damage individual cells in both primary mouse cortical astrocytes and an established astrocyte cell line. In both cases, the release of material/substances from laser-irradiated astrocytes or neurons induced a phagocytic response in near-by astrocytes. Propidium iodide stained DNA originating from irradiated cells was visible in vesicles of neighboring cells, confirming phagocytosis of material from damaged cortical cells. In the presence of an intracellular pH indicator dye, newly formed vesicles correspond to acidic pH fluorescence, thus suggesting lysosome bound degradation of cellular debris. Cells with shared membrane connections prior to laser damage had a significantly higher frequency of induced phagocytosis compared to isolated cells with no shared membrane. The increase in phagocytic response of cells with a shared membrane occurred regardless of the extent of shared membrane (a thin filopodial connection vs. a cell cluster with significant shared membrane). In addition to the presence (or lack) of a membrane connection, variation in phagocytic ability was also observed with differences in injury location within the cell and distance separating isolated astrocytes. These results demonstrate the ability of an astrocyte to respond to the damage of a single cell, be it another astrocyte, or a neuron. This single-cell level of analysis results in a better understanding of the role of astrocytes to maintain homeostasis in the CNS, particularly in the sensing and removal of debris in damaged or pathologic nervous tissue.