Lymphoblastoid transmembrane potential in bipolar patients, their siblings, and unrelated healthy comparison subjects

Olfactory Neuroepithelial Neural Progenitor Cells from Subjects with Bipolar I Disorder

Background:

Research into the pathophysiology of bipolar disorder (BD) is limited by the inability to examine brain cellular processes in subjects with the illness.

Methods:

Endoscopic biopsy was performed in subjects with bipolar I disorder to establish olfactory neural progenitor (ONP) cell lines. Olfactory function was assessed prebiopsy and postbiopsy using the University of Pennsylvania Smell Identification Test (UPSIT). Cells were characterized to determine their lineage.

Results:

There were no significant complications associated with the biopsy procedure, including olfaction. Outpatient olfactory neuroepithelial biopsy yielded ONP cells in three out of 13 biopsy attempts (23.1%). ONPs were positive for neuron-specific proteins (β-tubulin III, nestin, hexaribonucleotide binding protein-3, and peripherin) and glia-specific proteins (glial fibrillary acidic protein and myelin basic protein).

Conclusions:

ONP cells can be obtained safely from awake outpatients and are potentially useful for pathophysiological studies of bipolar illness and perhaps other neuropsychiatric conditions. Such cells allow for the investigation of potential pathological cellular processes without the confounding factors of genetic manipulation, which is required for induced pluripotent cells.

Cellular models to study bipolar disorder: A systematic review

BACKGROUND

There is an emerging interest in the use of cellular models to study psychiatric disorders. We have systematically reviewed the application of cellular models to understand the biological basis of bipolar disorder (BD).

METHOD

Published scientific literature in MEDLINE, PsychINFO and SCOPUS databases were identified with the following search strategy: [(Lymphoblastoid OR Lymphoblast OR Fibroblast OR Pluripotent OR Olfactory epithelium OR Olfactory mucosa) AND (Bipolar disorder OR Lithium OR Valproate OR Mania)]. Studies were included if they had used cell cultures derived from BD patients.

RESULTS

There were 65 articles on lymphoblastoid cell lines, 14 articles on fibroblasts, 4 articles on olfactory neuronal epithelium (ONE) and 2 articles on neurons reprogrammed from induced pluripotent stem cell lines (IPSC). Several parameters have been studied, and the most replicated findings are abnormalities in calcium signaling, endoplasmic reticulum (ER) stress response, mitochondrial oxidative pathway, membrane ion channels, circadian system and apoptosis related genes. These, although present in basal state, seem to be accentuated in the presence of cellular stressors (e.g. oxidative stress--rotenone; ER stress--thapsigargin), and are often reversed with in-vitro lithium.

CONCLUSION

Cellular modeling has proven useful in BD, and potential pathways, especially in cellular resilience related mechanisms have been identified. These findings show consistency with other study designs (genome-wide association, brain-imaging, and post-mortem brain expression). ONE cells and IPSC reprogrammed neurons represent the next generation of cell models in BD. Future studies should focus on family-based study designs and combine cell models with deep sequencing and genetic manipulations.

Evaluating the validity of blood-based membrane potential changes for the identification of bipolar disorder I

OBJECTIVE

The objective of this study was to develop a diagnostic blood test for bipolar disorder I using membrane potentials as biological markers.

METHODS

We measured the fluorescence intensity of a dye sensitive to membrane potential in whole blood samples from bipolar I, unipolar, schizophrenic patients, and psychiatrically normal controls. Patients were diagnosed through structured clinical interviews according to DSM-IV. Both the t-test and logistic regression analysis were used to analyze the data.

RESULTS

The membrane potential as indicated by the fluorescence intensity of the membrane potential dye in blood cells drawn from patients with bipolar disorder I was significantly different from the blood cells drawn from unipolar and schizophrenic patients, and from psychiatrically normal controls (P<0.001). The specificity and sensitivity were determined to be 0.88 and 0.78 respectively which compared well with the state of the art diagnostic techniques for other diseases. Logistic regression analysis revealed that the membrane potential was a reliable predictor which could be used as a diagnostic marker for bipolar I.

CONCLUSIONS

These results indicate that the membrane potential of blood cells can be used as a diagnostic marker to augment the DSM-IV diagnosis of bipolar disorder I. Expanded clinical trials are needed to establish this technique for general use.

Lamotrigine and the treatment of mania in bipolar disorder

Anticonvulsants, including valproate and carbamazepine, have established efficacy in the treatment of mania. The anticonvulsant, lamotrigine. has been reported to have antimanic and antidepressant efficacy, and mood-stabilising effects in case reports and preliminary open trials. The efficacy and tolerability of lamotrigine has been compared with olanzapine and lithium in a randomised, prospective, controlled fashion over a period of 4 weeks treatment in a total of 45 hospitalised patients with DSM-IV-defined mania. Significant improvements of a similar magnitude were observed for all treatment groups and lamotrigine was well tolerated. Mechanisms of action proposed to explain the antimanic activity of lamotrigine include inhibition of voltage-sensitive and use-dependent sodium channels, inhibition of glutamate release and calcium channel blockade. Platelet studies have indicated supersensitivity of glutamate receptors and increased intracellular calcium concentrations in patients with mania. Further clinical and mechanistic studies of lamotrigine use in mania are warranted.