Hi Mohit,

Cell based assays are in vitro assays. In vitro roughly means “in test tube”, while in vivo means roughly “in life”. In vivo assays involve the use of animals. In vitro assays like cell based assays and receptor binding assays involve tissue derived from animals. The receptor based in vitro assays generally involve using a protein extract from tissue and placed in petri dishes or plates with smaller wells for analysis. The cell based in vitro assays generally use immortalized cancer cells. These cancer cells are grown in plastic dishes and then placed in petri dishes or plates with smaller wells for analysis.

Very Thank u Sir , for this brief explanation.................

From ur explanation.in my mind certain querries r there-:

1. How this protein is extracted from tissue as there r number of proteins(enzymes, and many others) expressed in tissue ,i know that receptor is protein too?

2. is it always neccessary to take immortalized cells but not normal healthy cells in any case?

3. ur above explanation concludes that we take whole cell other than specific protein in tissue......?

4. where can i find detail explanation..........from where i can have a review for that??

Thank u

Yours sincerely,

Mohit Kwatra

(India)

Hi Mohit,

1. There are a number of ways to extract proteins form tissue or cells. First you simply grow or collect the tissue of interest. Then you must break apart the tissue and start separating the proteins. There are numerous techniques for this which can be found in most biochemistry texts, but they include fracturing the cells, centrifugation and precipitating out the protein of interest. Purity of the protein depends on the test being run. Some require very pure protein, others do not.

2. Both immortalized cells and normal tissue can be used in cell bioassays. Most people like the immortalized cancer cells because they reproduce by themselves and are very easy to work with. However it depends on what you are trying to study. Some studies require normal tissue.

3. For cell bioassays, yes, you use the whole cell for the test. Often people will use a small trey with 96 wells. They grow the cells in the wells and then add the chemical of interest to some of the wells, leaving some wells without the chemical of interest to act as the base line or “negative control”. They then look at all of the wells to see the difference. The difference may be cell growth, cell death, or other markers used to see the desired effect.

4. Google is your best bet for finding good explanations of “in vitro”, “in vivo” and cell bioassays. Wikipedia also does a good job. http://en.wikipedia.org/wiki/Bioassay

Hello John ,

Thanks for this well structured response........

I appreciate your support.

Best Regards ,

Mohit Kwatra(New Delhi,India)

Cell based assays qualitatively measure the function of the product/molecule. Assay plays a key role in determining the quality of biological products. Potency can be determined with  relevant cell-based assays, not just by one assay. Assay designing depends on molecule's MOA. In simple terms determining drug quality before risking in pre-clinical studies.