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Morphological changes in rat hepatocytes in primary culture induced by Misonidazole, desmethylmisonidazole and Ro
Abstract:
Isolated rat hepatocytes in early primary culture were incubated in the presence of three substituted nitroimidazoles currently of clinical interest as tumour radiosensitisers. The effects of 3h treatments with Misonidazole (MISO), Desmethylmisonidazole (DESMISO) and the basic compound Ro 03-8799 were monitored both directly from treatment and following a 24h 'recovery' period. Morphological changes were observed by SEM and TEM and included effects on the plasma membrane and the nucleus. The plasma membrane of DESMISO and 03-8799 treated cells was characterised by blebbed regions not present in control cultures, and considered indicative of an early toxic insult. Blebs were most evident in 03-8799 treated hepatocytes where they often contained coils of endoplasmic reticulum within the ground plasma. Blebbed areas were less evident 24h after the removal of the drugs from surviving cells. An increased aggregation of peripherally located heterochromatin within the nucleus was the other main morphological alteration induced by nitroimidazole treatment. This was again more prevalent in 03-8799 and DESMISO exposures; and particularly in cells demonstrating membrane damage. Parallel viability studies indicated an efficacy of the nitroimidazole towards rat liver parenchymal cells in primary culture of Ro 03-8799 greater than DESMISO greater than MISO. This fitted the order predicted from the morphological findings and from previously published clinical data. The validity of monitoring structural parameters as a means of initially indicating lesion sites following drug treatments in the hepatocyte cytotoxic screening model is considered.
Insights
This study investigated the toxic effects of three nitroimidazoles on rat hepatocytes. Ro 03-8799 showed greater toxicity than Desmethylmisonidazole and Misonidazole, impacting cell membranes and nuclei.
Area of Science:
- Cell Biology
- Toxicology
- Pharmacology
Background:
- Nitroimidazoles are clinically relevant as tumor radiosensitizers.
- Understanding their cytotoxic effects on normal tissues is crucial for therapeutic applications.
Purpose of the Study:
- To evaluate the morphological and cytotoxic effects of Misonidazole (MISO), Desmethylmisonidazole (DESMISO), and Ro 03-8799 on isolated rat hepatocytes.
- To correlate structural changes with cell viability to assess the efficacy of these radiosensitizers.
Main Methods:
- Primary rat hepatocyte cultures were treated with MISO, DESMISO, and Ro 03-8799 for 3 hours.
- Morphological changes were analyzed using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).
- Cell viability was assessed following drug treatment and a 24-hour recovery period.
Main Results:
- Nitroimidazole treatment induced morphological alterations, including plasma membrane blebbing and nuclear heterochromatin aggregation.
- Ro 03-8799 exhibited the most pronounced membrane damage and heterochromatin changes.
- Cell viability assays revealed a toxicity order of Ro 03-8799 > DESMISO > MISO.
Conclusions:
- Morphological changes in hepatocytes serve as reliable indicators of early cytotoxic insult from nitroimidazole treatment.
- The observed toxicity profile in vitro aligns with clinical data, validating the hepatocyte model for screening radiosensitizers.