Evaluation of spiramycin for topical applications: a cell culture study

O. Yagiz Aghayarov, N. Bayar Muluk, C. Vejselova Sezer, H.M. Kutlu, C. Cingi

Department of Otorhinolaryngology, Izmir Health Sciences University, Tepecik Training and Research Hospital, Izmir, Turkey. nbayarmuluk@yahoo.com

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• Otorhinolaryngology

OBJECTIVE: Through a cell culture test, we analyzed the cytotoxic effects of topical spiramycin on NIH/3T3 fibroblast cells.

MATERIALS AND METHODS: Dulbecco’s Modified Eagle Medium (DMEM) supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin was used for the growth of NIH/3T3 fibroblast cells in a 5% CO2 incubator. Spiramycin’s cytotoxicity was measured using the MTT assay. 5,000 NIH/3T3 cells per well of a 96-well plate were seeded in each well, and the cells were treated with spiramycin (3.13-100 μM) for 24, 48 and 72 hours while the plates were incubated at 37°C in a humidified 5% CO2 atmosphere. First, 105 NIH/3T3 cells were seeded onto coverslips in 6-well plates for morphological analysis of both untreated and spiramycin-treated cells. For 24 hours, NIH/3T3 cells were exposed to a 100 μM dosage of spiramycin. The cells in the control group were grown in complete growth media alone.

RESULTS: Spiramycin was non-toxic to NIH/3T3 fibroblast cells in a MTT test. The concentration of spiramycin used to stimulate cell growth increased as the concentration was increased. After 24 and 48 hours of treatment with 100 μM NIH/3T3, the cells showed the most significant increase in size. Cell viability was shown to be significantly reduced at spiramycin doses of 50 and 100 μM. All MTT findings revealed that spiramycin enhanced cell viability and was not harmful to the fibroblast cells for short-term application of 24 and 48 hours but lowered the viability of fibroblast cells at the doses of 50 and 100 μM for long-term application duration of 72 hours. Confocal micrographs showed that spiramycin treatment did not affect the cytoskeleton or nucleus of fibroblast cells, in contrast to the control NIH/3T3 cells. Both untreated and treated with spiramycin, fibroblast cells were found to be fusiform and compact, with their nuclei remaining unaltered and unreduced in size.

CONCLUSIONS: It was concluded that spiramycin has a beneficial effect on fibroblast cells and is safe for use over short periods. Spiramycin reduced fibroblast cell viability when applied for 72 hours. Confocal micrographs showed that fibroblast cell skeletons and nuclei were unharmed and undamaged, that cell shapes were fusiform and compact, and that nuclei were neither broken nor shrunken. Topical spiramycin could be recommended for septorhinoplasty procedures due to anti-inflammatory effects for short-term usage if clinical trials will confirm experimental data.

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