Cell-based assays can be used to test the overall cell growth or death caused by lysis, necrosis, or apoptosis in response to stress and external stimuli. Creative Bioarray provides both luminescent-based and fluorescent-based methods to test the efficacy of candidate compounds to cell proliferation/viability.
Creative Bioarray offers four solutions for cell proliferation/viability assays: metabolic activity testing, DNA synthesis measurement, detection of ATP concentration and proliferation markers. Endpoint detection or dynamic monitoring of proliferation is available according to the assays you choose.
Metabolic activity is tested by using a spectrum of tetrazolium salt dyes including MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium), or XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide). After being added to the cells to be tested, the dye will be reduced by actively growing cells to formazan product with a changed color which can be detected via spectrophotometer.
DNA synthesis measurement is one of the most accurate and sensitive assays for cell proliferation, especially for slow growing cells. Creative Bioarray offers radioactive label 3H-thymidine and non-radioactive label 5-bromo-2'-deoxyuridine (BrdU) to detect DNA synthesis. The labels can be incorporated into newly synthesized DNA in proliferating cells, which then be detected.
ATP detection assays are based on the intact regulation of intracellular ATP within live cells. In the cell lysate collected from live cells, ATP concentration exhibits a linear relationship with cell number, which is absent in dying or dead cells. The bioluminescent ATP detection platform at Creative Bioarray utilizes the light from the reaction of ATP produced by live cells and added luciferin catalyzed by the enzyme luciferase, which is proportional to the ATP concentration. This platform is very sensitive and the readout can be easily detected by a luminometer, which is well suited to HTS assays.
Immunohistochemical detection of proliferation markers is another effective way to monitor cell proliferation. Many antigens specifically present in proliferating cells have been identified as proliferation markers. For example, human Ki-67 protein, only expressed during the S, G2 and M phases of the cell cycle, can be recognized by its specific antibody. Besides of Ki-67, Creative Bioarray measures protein levels of other proliferation markers, such as PCNA (proliferating cell nuclear antigen) and MCM 2 (minichromosome maintenance 2), to detect cell proliferation in an immunohistochemical way.