ClonaCell™-CHO CD Medium is a methylcellulose-based semi-solid medium recommended for selection and cloning of Chinese hamster ovary (CHO) cells. This medium is chemically defined, protein-free, and animal component-free. It does not contain L-glutamine, selection agents, or phenol red and is compatible with dihydrofolate reductase (DHFR) and glutamine synthetase (GS) selection systems.
Benefits of semi-solid cloning:
• Individual clones and their progeny remain localized together in a semi-solid matrix as they grow to form distinct monoclonal colonies. This prevents the loss of rare, high-producing clones by overgrowth from faster-growing cells, as can occur during selection in a liquid medium, and facilitates the isolation of a diverse set of clones with a wide range of growth rates and productivities to be obtained for downstream screening.
• Colonies obtained from semi-solid medium have a high probability of monoclonality, allowing clonal cell lines to be generated in less time and using fewer resources than with limiting dilution cloning.
• Colonies can be easily picked from the semi-solid medium by manual or robotic methods and dispersed into a liquid growth medium for screening and expansion.
• Enables single-cell cloning and expansion of CHO cells in a chemically defined, protein-free, animal component-free medium
• Kolliphor P188
• Other ingredients
Semi-Solid Media, Specialized Media
Cell Culture, Semi-Solid Cloning
Area of Interest
Antibody Development, Cell Line Development, Drug Discovery and Toxicity Testing
Protocol for Cloning CHO Cell Lines Using ClonaCell™-CHO Semi-Solid Medium
Video Tutorial: Probability of Monoclonality
Why Use Semi-Solid Medium for Cloning Hybridomas and CHO Cells
How to Perform Semi-Solid Cloning of CHO Cell Lines in 96-Well Plates Using ClonaCell™-CHO Medium
Semi-Solid Cloning of CHO Cells Using ClonaCell™-CHO Medium
Frequently Asked Question
Is the serum in ClonaCell™-TCS medium heat inactivated?
Yes, all serum used in ClonaCell™ is heat inactivated.
Is there any IgG in ClonaCell™ TCS?
While we don't add IgG to the ClonaCell™ media, we do add serum, which contains an undefined amount of IgG. We selectively use serum lots with low IgG levels in the production of ClonaCell™ media, however, levels vary from lot to lot. IgG levels in a specific lot of ClonaCell™ TCS medium are available in the lot-specific Certificate of Analysis.
Can ClonaCell™-TCS be used with any cell line?
A list of recommended cell lines can be found in the manual. Other cell lines may be compatible with ClonaCell™-TCS. It will be necessary, however, to determine the plating cell density and growth efficiency of the desired cells in ClonaCell™-TCS.
Why do I get more cells when I select my fusion in liquid medium rather than in methylcellulose-based semi-solid medium?
Cells grown in liquid medium may appear to grow more rapidly than in methylcellulose-based medium. This is often due to the presence of a few rapidly growing clones that multiply quickly and become abundant in liquid culture, overgrowing clones that grow more slowly. In methylcellulose cultures, the rapidly growing cells remain in close proximity to each other, resulting in large colonies, each derived from a single fusion or transfection product. The large clones don't overgrow smaller, slower growing colonies, which can be separately isolated.
How do I thaw ClonaCell™ methylcellulose-based semi-solid medium?
We recommend thawing the medium overnight in a refrigerator at 4°C and mixing well.
How do I measure and dispense methylcellulose semi-solid medium?
We recommend using a 12 mL syringe with a 16 gauge needle attached (blunt end needles are recommended for safety purposes). Do not dispense the semi-solid media/cell mixture using serological pipettes as the media will stick to the pipette walls, resulting in inaccurate dispensed volumes and loss of cells.
My ClonaCell™ methylcellulose semi-solid medium appears runny. Why does this happen?
"Runny" methylcellulose could be a result of improper handling. Diluting the methylcellulose with too much liquid medium, or insufficient mixing before use, will result in methylcellulose with altered viscosity. Excessive condensation on the inside of the cell culture dish lid can result in water dripping onto the cultures, lowering viscosity. Additionally, bumping, shaking or other sudden movement of the culture may also disrupt the colonies. Note: methylcellulose is less viscous at room temperature than at 37°C.
What is the optimal number of colonies per plate?
We recommend 50-150 colonies per plate. As it is difficult to anticipate the numbers of colonies after a fusion or transfection, we recommend plating at three different densities to increase the likelihood of achieving a plating density of approximately 100 colonies per plate. This density allows sufficient space between the colonies to allow for easy colony picking.
There are still bubbles in the media after I plate my cells. Do I need to disrupt the bubbles?
We recommend that you avoid creating large bubbles during plating, but there is no need to manually pop or disperse the small bubbles after plating. They will disperse over the incubation period of 10-14 days.
Do I ever need to re-clone cultures grown with ClonaCell™ semi-solid medium?
Re-cloning is a good practice to observe and is recommended if the number of colonies in the original dishes was very high.
Once I pick the colonies and grow the cells in plates, will the residual methylcellulose interfere with characterization? For example, will I have problems doing an ELISA?
There will likely be some residual methylcellulose contamination when colonies are picked and transferred to the 96-well plate with the liquid growth medium. The concentration of methylcellulose, however, should be low enough that it should not interfere with most assays.
How important is the incubator humidity when culturing in methylcellulose-based medium?
Very important. In situations where the humidity is not high enough, we recommend that the 100 mm Petri dishes should be placed with an open dish containing sterile water inside a larger plastic container with a lid. Without very high humidity, the media will dry out over the culture period and this will impede the growth of the colonies.
Do I have to use 100 mm petri dishes or can I use other cultureware?
We recommend 100 mm Petri dishes as these have been used to develop and test ClonaCell™ semi-solid media. We have found that the surface area of these dishes allows for easy colony picking. Other sizes of dish (e.g. 6-well plates) can be used. It is important to use non-coated dishes to prevent cells from sticking to the bottom of the plate and obscuring the colonies. The volume of media plated should be adjusted to reflect the surface area of the dish being used.
Are there any selective agents in ClonaCell™-CHO ACF or ClonaCell™-CHO CD?
These media do not contain hypoxanthine, aminopterin, thymidine, glutamine, or any other selective agents or antibiotics. These media are therefore fully customizable. Both ClonaCell™-CHO ACF and ClonaCell™-CHO CD are compatible with dihydrofolate reductase (DHFR) and glutamine synthetase (GS) selection.
My cells grow fine in ClonaCell™-CHO ACF but I do not see colony growth in ClonaCell™-CHO CD. Why?
The plating density for successful colony growth in protein-free medium needs to be higher than what is recommended for medium that contains protein. The optimal plating density should be determined empirically by plating several cell densities. For example, when re-cloning established cell lines, we recommend testing 200-1000 cells per 100 mm plate for ClonaCell™-CHO ACF and testing 2000-10000 cells per 100mm dish for ClonaCell™-CHO CD.
What medium do you recommend for the expansion of clones after selection in ClonaCell™-CHO ACF or ClonaCell™-CHO CD?
CHO cells selected in either ClonaCell™-CHO ACF or ClonaCell™-CHO CD semi-solid medium can be expanded in ClonaCell™-CHO CD Liquid medium.
How many cells should I plate for cloning in ClonaCell™-CHO CD?
Cloning efficiencies vary for different clones and cell lines. For optimal cloning efficiencies, cells should be in logarithmic phase prior to plating. If you have had previous experience with cloning in a chemically defined liquid medium, plating cell concentration that would result in ~100 clones may be used to plate in semi-solid medium (e.g. If plating at 1 cell/well in a 96-well plate results in 10 wells being positive for clones, plating 1000 cells per 100mm plate in semi-solid medium would be a good starting cell concentration to test). A minimum of three plating cell concentrations is recommended. If no work has been previously done with the specific cell line, we recommend a range of 25 000 - 100,000 cells per 100 mm dish for selection and cloning after transfection, and 2000 - 10,000 cells per 100 mm dish for subcloning. Additional optimization of cell concentrations may be necessary.
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It has been 50 years since cellular senescence was first described in human diploid fibroblasts (HDFs), yet its mechanism as well as its physiological and clinical implications are still not fully appreciated. Recent progress suggests that cellular senescence is a collective phenotype, composed of complex networks of effector programs. The balance and quality within the effector network varies depending on the cell type, the nature of the stress as well as the context. Therefore, understanding each of these effectors in the context of the whole network will be necessary in order to fully understand senescence as a whole. Furthermore, searching for new effector programs of senescence will help to define this heterogeneous and complex phenotype according to cellular contexts.
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