Sahar Moghbeli Nejad - Department of Medical Genetics, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Hossein Mozdarani - Department of Medical Genetics, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Mohammad Ali Shokrghozar - National Cell Bank of Iran, Pasteur Institute, Tehran, Iran.
Vahideh Farahat - National Cell Bank of Iran, Pasteur Institute, Tehran, Iran.

Objective(s) The main objective of this study was to investigate the status of chromosome stability in ۳ human-mouse hybridoma cell lines over a period of time in various passages. Materials and Methods Metaphase spreads from ۳ human-mouse cell lines (HF۲X۶۵۳, SPMO-۴ and F۳B۶) that had been cultured in ۴ successive passages, from ۱ to ۴ weeks, were prepared and analyzed. Metaphase chromosomes stained in Giemsa and a fluorescent dye, Hoechst ۳۳۲۵۸, for differential staining. This staining was performed for differentiating human and mouse chromosomes. Results Numerical chromosome analysis showed that although in successive passages the total number of chromosomes in hybridoma cells remained unchanged, some changes occurred in the number of human and mouse metacentric and acrocentric chromosomes during different passages. These changes were detectable, using fluorescence staining method. Conclusion Since one of the main uses of human-mouse hybridoma cells is producing monoclonal antibody, chromosomal instability in these cells causes the loss of human chromosomes coding the antibody of interest occasionally. Therefore, cytogenetical analysis and characterization of these cells, especially by using the appropriate ways of chromosomal identification, is essential prior to use.

Chromosomal instability, Hoechst ۳۳۲۵۸, Hybrid cells, Staining