Accelerating the Pace of Discovery

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At Exalpha Biologicals our aim is to make continuous improvements while providing the best quality and value for our customers. As part of this mission, we are proud to relaunch our updated BrdU Immunohistochemistry Kit (product code #X1545K.1) produced using more animal-friendly manufacturing processes.

Bromodeoxyuridine (BrdU) is a thymidine analog which is selectively incorporated into the DNA of proliferating cells, providing a marker for DNA replication during the S-phase of the cell cycle. This allows the number of BrdU labeled proliferating cells to be quantified in cell lysates, cell suspensions or tissue sections using a BrdU-specific antibody. Historically, the detection of cell proliferation was performed by the measurement [3H] thymidine uptake; a slow, labor intensive technique which involved the handling and disposal of radioisotopes, and expensive equipment.

Our BrdU Immunohistochemistry Kit (X1545K.1) can be used for the immunohistochemical staining of BrdU labeled tissues, using formalin-fixed, paraffin-embedded (FFPE) sections or frozen sections, and the immunocytochemical staining of formalin-fixed cells. BrdU labeling, detected using biotinylated antibody, is further labeled with Streptavidin-HRP and visualized by addition of DAB (diaminobenzidine) substrate. A hematoxylin counterstain is provided with the kit, and the material included is sufficient to run 50 slides.

Our improvements

Exalpha Biologicals has developed a cell-based alternative to the mouse intestinal tissue sections previously used as control slides within the kit. Formalin-fixed MCF7 cells labeled with BrdU (also available separately, product code# J0169) are included. Five control slides are provided in total, one a prestained example of a positive reaction, and a further four unstained slides for use alongside the experimental slides, to act as controls for the immunostaining procedure. The unstained slides act as both positive and negative controls with approximately 50% of the cells displaying strong positive staining and the remainder remaining completely negative. See sample pictures below.


  • More efficient animal-friendly manufacturing process
  • The MCF-7 cells are labeled with an exact concentration of BrdU, meaning low/negligible batch-to batch variation
  • Controls are more relevant to experimental samples. Many researchers and pharmaceutical companies use the BrdU kit to test the efficacy of drugs that influence proliferative capacity using specific cell cultures
  • Slides can be kept frozen while still maintaining their morphology, and can withstand multiple freeze-thaw cycles
  • Ease of interpretation compared to tissue sections, no knowledge of the morphology of intestinal tissue is required (see sample pictures below)
Figure 1
Figure 2

Sample Pictures

Example picture of formalin-fixed MCF7 cells labeled with BrdU stained using Exalpha’s BrdU Immunohistochemistry kit. More diffuse nuclear immunostaining (Figure 1) can be seen next to a more localized nuclear staining reaction (Figure 2).