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Cell passaging

Adherent cultures should be passaged when they are in the log phase before they reach confluence, otherwise, it takes them longer to recover when reseeded. Normally, you can detect that visually by estimating the percentage of confluence as the amount of free space between cells. Usually, the normal range to perform the cell passage is 70-90%. It is also important to passage your cells according to a programmed schedule to ensure a reproducible behavior that allows you to monitor their health status. Deviations from the growth patterns usually indicate that the culture is unhealthy or a component of your culture system is not functioning properly. Therefore, it is strongly recommended to keep a detailed cell culture log of the cell growth.

Dissociation techniques

The first step in subculturing adherent cells is to detach them from the surface of the culture vessel. You can do that using enzymatic or mechanical procedures, as you can see in the table below.

Table 1. The headings are procedure and dissociation agent. Under procedure, there are three rows: shake-off, scraping, and enzymatic dissociation. Under dissociation agent, Corresponding to the shake-off procedure, there is shaking or rocking of culture vessel or vigorous pipetting. On the same row as scraping, the dissociation agent is cell scraper. When it comes to enzymatic dissociation, trypsin, trypsin plus collagenase, and dispase are used.

Figure 1. Dissociation techniques