Trypsin is an essential reagent for routine cell culture work. In the cultivation of mammalian cells, it has been extensively used for cell isolation from tissues or cell dislodging in subculturing. It may damage the cell membrane in contact of cells during long trypsinization. However, there is no specific report on time-dependent effect of trypsinization on cells. In the present study, we investigated the time dependent effects of trypsinization on equine chondrocytes. Cell viability after trypsinization with 0.25% trypsin-EDTA for 5 to 60 minutes was quantified by trypan blue exclusion assay, propidium iodide-Hoechst double staining, flow cytometry analysis and XTT assay. The results showed that trypsin-EDTA decreased the proliferation of equine chondrocytes depending on the exposure time of trypsinization. After 20 and 60 minutes of trypsinization, the cell membranes were strongly affected and the percentages of viable cells reduced to 91% and 85% respectively detected by trypan blue exclusion assay. Similar results were observed both in flow cytometric evaluation and propidium iodide-Hoechst double staining. The XTT assay result also showed decreased cell viability with the extended time of trypsinization. In order to minimize the time dependant cytotoxicity of trypsinization, as minimum as short time exposure is suggestive that maximizes live cell isolation from tissue as well as subculture of equine chondrocytes or other cells.

Key words: Cell culture; Equine chondrocytes; Trypsinization; Viability