Specific accumulation of ¹⁸F-deoxyglucose in three-dimensional long-term cultures of human and rodent brain tissue

Summary

Aim: Organotypic slice cultures (OSC) of human brain specimens represent an intriguing experimental model for translational studies addressing, e.g., stem cell transplantation in neurodegenerative diseases or targeting invasion by malignant glioma ex vivo. However, long-term viability and phenomena of structural reorganization of human OSC remain to be further characterized. Here, we report the use of ¹⁸F-deoxyglucose (FDG) for evaluating the viability of brain slice preparations obtained either from postnatal rats or human hippocampal specimens. Methods: Anatomically well preserved human hippocampi obtained from epilepsy surgery and rat hippocampus slice cultures obtained from six day old Wistar rats were dissected into horizontal slices. The slices were incubated with FDG in phosphate buffered saline up to 1 h, either with or without supplementation of glucose at a concentration of 2.5 mg/ml. Radioactivity within the medium or slice cultures was measured using a gamma-counter. In addition, distribution of radioactivity was autoradiographically visualized and quantified as counts per mm². Results: In rat hippocampal slices, FDG accumulated with 1 300 000 ± 68 000 counts/mm², whereas the incorporation of the radioactive label in human slices was in the order of 1 500 000 ± 370 000 counts/ mm². The elevation of glucose concentration within the medium led to a significant three-fold decrease of FDG accumulation in rat slices and to a 2.4-fold decrease in human specimens. Conclusions: FDG accumulated in organotypic brain cultures of human or rodent origin. FDG is thus suited to investigate the viability of OSC. Furthermore, these preparations open new ways to study the factors governing cerebral FDG uptake in brain tissue ex vivo.

Zusammenfassung

Ziel: Organotypische Hirnschnittkulturen (OSC) sind ein experimentelles Modell für Hirnerkrankungen. Jedoch müssen die längerfristige Lebensfähigkeit und Strukturreorganisation von menschlichen Hirnschnitten in Kultur weiter charakterisiert werden. Methoden: Wir untersuchten die Anreicherung von ¹⁸F-Deoxyglukose (FDG) in OSC aus postnatalen Ratten (n = 18)und menschlichen hippokampalen Operationspräparaten (n = 3). Die Hippokampi wurden in horizontale Scheiben geschnitten und mit FDG bis zu 1 h inkubiert. Die Verdrängung von FDG erfolgte durch Zusatz von Glukose (2,5 mg/ml). Die Radioaktivitätskonzentration im Medium und im gesamten Schnitt wurde am Gammacounter gemessen, die Verteilung der Radioaktivität autoradiographisch dargestellt. Ergebnisse: In den hippokampalen Schnitten der Ratte reicherte sich FDG in einer Stunde mit 1 300 000 ± 68 000 counts/mm² an, wohingegen sich für die menschlichen Hirnschnitte 1 500 000 ± 370 000 counts/mm² ergaben. Durch die Erhöhung der Glukosekonzentration im Medium kam es zu einer dreifachen Abnahme der FDG-Aufnahme im Hirnschnitt der Ratte und zu einer 2,4fachen Abnahme der FDG-Aufnahme im humanen Hirnschnitt. Schlussfolgerungen: OSC reichern FDG spezifisch an. Dieser Tracer eignet sich deshalb prinzipiell zur Kontrolle ihrer Vitalität. Ferner stellen OSC ein interessantes Ex-vivo-Modell für Faktoren dar, die die zerebrale FDG-Anreicherung beeinflussen.

Keywords

Radioimaging - autoradiography - glucose metabolism - ¹⁸F-deoxyglucose - organotypic brain cultures

Schlüsselwörter

Autoradiographie - Glukosemetabolismus - ¹⁸F-Deoxyglukose - organotypische Hirnschnittkulturen

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