Objective-To evaluate the numbers and proportions of olfactory ensheathing cells (OECs) in cell cultures derived from the olfactory bulb (OB) and olfactory mucosa of dogs. Animals-7 dogs. Procedures-OB tissue and olfactory mucosa from the nasal cavity and frontal sinus were obtained from euthanatized dogs and prepared for cell culture. At 7, 14, and 21 days of culture in vitro, numbers and proportions of OECs, astrocytes, and fibroblasts were determined via immunocytochemistry. Antibody against the low-affinity nerve growth factor receptor p75 was used to identify OECs, antibody against glial fibrillary acidic protein was used to identify astrocytes, and antibody against fibronectin was used to identify fibroblasts. Results-Cultured OECs derived from the olfactory mucosa of the nasal cavity and frontal sinus had similar characteristics. However, whereas OECs in the OB cell cultures constituted approximately 50% of the cells at 7 days and approximately 75% at 21 days the proportion of OECs in cultures derived from both mucosal types was much lower, with approximately 40% OECs at 7 days and approximately 25% at 21 days. Analysis of OEC numbers revealed that these changes were accompanied by corresponding decreases and increases in the population of cells with fibronectin receptors. Conclusions and Clinical Relevance-Although olfactory mucosal cell cultures yielded a sufficient number of OECs for spinal cord transplantation procedures in dogs, modification of culture conditions would be required to ensure that the derived cell population contained a sufficient proportion of OECs.

The LEC rat is reported to exhibit hypersensitivity to X-irradiation, deficiency in DNA double-strand break repair, and radio-resistant DNA synthesis. This character of the LEC rat has been thought to be due to abnormal G1 arrest in cells after X-irradiation. In this report, we re-investigated the effect of X-irradiation on the cell cycle in primary-cultured fibroblasts. Primary-cultured fibroblasts derived from LEC and BN rats were exposed to 4 Gy of X-ray and their cell cycle analysis was performed with a flow cytometer. Fibroblasts derived from both rats showed normal response of the cell cycle, indicating the arrest at both G1- and G2/M-phase and no difference in the cell cycle population between fibroblasts derived from both rats. In contrast, when the same analysis was performed using the cell line, L7 and W8, which had been established from the lung fibroblasts of LEC and control WKAH rats, respectively, by immortalizing with SV40 T-antigen, L7 cells but not W8 cells showed impaired G1 arrest and abnormal cell cycle. These results suggest that fibroblasts derived from LEC rats possess the normal cell cycle response after X-irradiation, if they are kept naive as not immortalized with SV40 T-antigen.