Characterization of an iPSC-based barrier model for blood-brain barrier investigations using the SBAD0201 stem cell line

BACKGROUND

Blood-brain barrier (BBB) models based on primary murine, bovine, and porcine brain capillary endothelial cell cultures have long been regarded as robust models with appropriate properties to examine the functional transport of small molecules. However, species differences sometimes complicate translating results from these models to human settings. During the last decade, brain capillary endothelial-like cells (BCECs) have been generated from stem cell sources to model the human BBB in vitro. The aim of the present study was to establish and characterize a human BBB model using human induced pluripotent stem cell (hiPSC)-derived BCECs from the hIPSC line SBAD0201.

METHODS

The model was evaluated using transcriptomics, proteomics, immunocytochemistry, transendothelial electrical resistance (TEER) measurements, and, finally, transport assays to assess the functionality of selected transporters and receptor (GLUT-1, LAT-1, P-gp and LRP-1).

RESULTS

The resulting BBB model displayed an average TEER of 5474 ± 167 Ω·cm2 and cell monolayer formation with claudin-5, ZO-1, and occludin expression in the tight junction zones. The cell monolayers expressed the typical BBB markers VE-cadherin, VWF, and PECAM-1. Transcriptomics and quantitative targeted absolute proteomics analyses revealed that solute carrier (SLC) transporters were found in high abundance, while the expression of efflux transporters was relatively low. Transport assays using GLUT-1, LAT-1, and LRP-1 substrates and inhibitors confirmed the functional activities of these transporters and receptors in the model. A transport assay suggested that P-gp was not functionally expressed in the model, albeit antibody staining revealed that P-gp was localized at the luminal membrane.

CONCLUSIONS

In conclusion, the novel SBAD0201-derived BBB model formed tight monolayers and was proven useful for studies investigating GLUT-1, LAT-1, and LRP-1 mediated transport across the BBB. However, the model did not express functional P-gp and thus is not suitable for the performance of drug efflux P-gp reletated studies.

[The value of postoperative radiotherapy in colonic carcinomas]

From 1979 to 1988 63 patients with cancer of the colon received postoperative adjuvant radiotherapy. The mean age was 62 years and the median follow-up period was 71 months. Pathologic staging showed a B1-tumour in nine cases, B2 in 25, C1 in three and a C2-tumour in 26 cases according to the Astler and Coller modification of the Duke's classification. 53 patients received doses between 41 and 50 Gy. 47 patients were treated with a 60Co megavoltage unit and 16 cases with 8 MV photons. The overall five years survival rate is 65%. There was no significant difference between the survival rates for all stages. Only four patients with primary positive lymph nodes experienced a local relapse. 16 developed metastatic disease. In twelve cases (19%) liver metastases appeared: four patients (6%) developed intraperitoneal metastases, one patient had a metastasis in the abdominal wall and another showed pulmonary carcinosis. Acute and transient side effects were seen in 35% of our patients. Three patients underwent a second operation for radiation induced bowel stenosis. Compared with the results of surgery adjuvant radiotherapy yields improved five-year survival data in patients with C2 and G4 tumours.