HER2/CD9 Exosome ELISA Kit (Human)

Cosmo Bio LTD

Catalog No: HAK-HELHER209-1

This
is a two-step sandwich ELISA kit that uses high-performance antibodies against exosome markers CD9 and HER2 to detect HER2 molecules expressed on the surface of exosomes secreted by cells in human blood and cell culture medium.

Background

What is HER2?

HER2 (human epidermal growth factor receptor type 2) is frequently overexpressed in various solid tumors. HER2 forms heterodimers with any of the other three receptors in the ErbB family. Heterodimerization of the receptor leads to autophosphorylation of tyrosine residues in the cytoplasmic domain of the heterodimer, initiating a signaling pathway that leads to cell proliferation and carcinogenesis1 ⁾ .
Molecular targeted therapy has been established for breast cancer with overexpression of HER2, and immunohistochemistry (IHC) is used to examine the overexpression of HER2 protein. In general, IHC testing is highly invasive and places a large burden on subjects, so research is also underway on liquid biopsies using exosomes that can reduce the burden. Exosomes are
also deeply involved in various diseases. In particular, HER2-positive exosomes secreted from HER2-positive breast cancer cells are problematic pathogenic factors that reduce the effectiveness of antibody drugs and promote metastasis of surrounding cancer cells2 ⁾ .
Until now, it has not been possible to directly measure exosomes derived from cancer cells that highly express HER2 quickly and easily. This product is a two-step sandwich ELISA kit that uses high-performance antibodies against CD9 and HER2, which are exosome markers, to detect HER2 molecules expressed on the surface of exosomes secreted by cells in human blood and cell culture fluid.

Features

• Direct quantification of HER2-positive exosomes in human blood samples, cell culture supernatants, etc.
• No special equipment is required; measurements can be performed with a standard plate reader.
• Stability and reproducibility are ensured by using HER2/CD9 fusion protein (standard protein) instead of exosomes themselves, which lack storage stability as a standard reagent.
• Relative quantification of each sample is possible by reading from a standard curve using HER2/CD9 fusion protein (standard protein).
• Detect human HER2-positive exosomes using a two-step sandwich method using immobilized HER2 antibody and HRP-labeled CD9 antibody.

Kit Components

Contents	capacity	quantity
Anti-HER2 antibody immobilized plate	96 well (8-well x 12 strips)	1 sheet
Standard protein (HER2/CD9 fusion protein)	100 µL	1pc ^*
Assay Buffer	25 mL	1 bottle
Washing buffer (10x)	25 mL	1 bottle
HRP-labeled anti-CD9 antibody (500x)	20 µL	1 bottle
Substrate solution	12 mL	1 bottle
Stop solution ( 2N H2SO4 )	6 mL	1 bottle
Plate seal	-	2 sheets

*; n=2, two calibration curves

Specification

Cross-reactivity	Sample Type	Measurement range	sensitivity
Human	serum, cell culture supernatant	4.688–300 ng/mL	Detection limit (DL) = 0.31ng/mL Quantitation limit (QL) = 0.93ng/mL

Example data

Figure 1. Standard curve

Figure 2. Measurement of purified exosomes
Exosomes purified by ultracentrifugation from the culture supernatant of the human breast cancer cell line SK-BR3-Luc were measured using this kit.