Cell Culture technology
What is the origin of Jianshun Biosciences cells? And are cells genetically modified by Jianshun Biosciences?

Except for EB66 suspension cells, which were not purchased from ATCC, all cell lines were purchased from this source. Suspension cells were adapted from adherent cells without further genetic modification.

Where can one find relevant information and culture conditions specific for each cell line?

Detailed information can be found for each cell line at the ATCC website, except for EB66 cells. ATCC gives specific cell type information such as, the source of the cells, culture and cryopreservation conditions, and references relevant to each cell strain.

Can cells be cultured in convex bottom plastic or glass flasks?

It is recommended to use disposable cell culture flasks in the early stage of cell recovery. Other culture vessels can be used after cell growth stabilizes.

Is the medium used in normal passaging of the cells the same as the medium used in virus production?

The medium used for normal passaging of the cells is not always that which is used during virus production. See cell-specific culture and transfection conditions for more detailed information regarding this inquiry.

Is it normal for the cell density of JSBio-HEK293 cells to reach 10⁷cells/ml?

Yes. With an initial cell density of 1.0 x 106 cells/mL, after 72 hours of incubation, the cell density may reach 10.0 x 106 cells/mL. 

Are there any limitations on passage number for suspension cell cultures?

There are no limitations on passaging for suspension cells, however optimal expression needs to be determined for each cell line to ensure optimal production and performance of the final products. Too many passages are not recommended.

How can one prevent mycoplasma contamination while culturing cells?

Using sterile techniques is required to prevent mycoplasma contamination in all cell cultures.  The best approach of prevention is to monitor cell strains for mycoplasma presence at various times during culturing of the cells to identify sources of mycoplasma contamination and to minimize contamination of adjacently cultured cells.

Why do suspension cells clump during culturing and how does one resolve this?

There are several reasons why suspension cells may clump during cultivation. These include:

(1)  The presence of calcium and magnesium ions. It is suggested to wash the cell with a balanced salt solution, not containing calcium and magnesium ions.

(2)  The condition of the cells has become poor because of overgrowth or other reasons causing clumping or the formation of a “dead cell ring” in the culture vessel. It is suggested to passage the cells to promote exponential cell growth of viable cells to reduce the number of dying cells and cell death factors in the growth medium.

(3)  Mycoplasma contamination. It is suggested that one regularly evaluate cell cultures for the presence of mycoplasma.

What is the standard cell density used for cryopreservation?

Generally, 1.0 x 107 cells/mL(vial).