A Detailed Introduction to Exosome Proteomics

Posted by Dora West on March 24th, 2022

What are exosomes?

Exosomes, a tiny membrane vesicle with a lipid bilayer structure, are secreted by most cells and are approximately 40-200 nm in diameter. exosomes are found in body fluids, including blood, saliva, urine and breast milk. exosomes of different tissue origins differ in content composition and function, and this difference is dynamically regulated by the extracellular matrix and microenvironment. Exosomes secreted by host cells or tumor cells are involved in tumorigenesis, growth, invasion and metastasis. The analysis and detection of exosomes can assist in early diagnosis, efficacy evaluation and prognostic analysis of the disease.

Exosome isolation and extraction method

For exosome research, isolation and collection of exosomes is a very critical step. There are several main methods for exosome collection: ultra-high speed centrifugation, density gradient centrifugation, magnetic bead immunization, ultrafiltration method, polymer precipitation, etc., and each method has different advantages and disadvantages. After extraction, exosomes need to be identified. Currently, electron microscopy techniques (morphological identification), NTA (particle size analysis), and Western blot assay (detection of marker proteins, such as CD9, CD63, CD81, TSG101, HSP70, etc.) are commonly used to identify exosomes.

Exosome proteomics research

Exosomes can affect the function of target cells by transmitting messages, activate cellular signaling pathways, and play a role in immune, coagulation, tumor and other physiopathological processes. And the differential expression of proteins among them is an important feature to distinguish exosomes of different origins and is an important way to study the origin of exosomes. Proteomics has gradually become an important tool for studying the proteomes of various subcellular fractions. Proteomics studies on exosomes can reveal the pathogenesis of diseases, search for biomarkers for disease diagnosis and prognosis, and screen for disease therapeutic targets.

Creative Proteomics offers differentiated exosome proteomics services based on the different needs of researchers.

1.        Tandem mass tag (TMT) quantitative proteomics

TMT is a classic high-throughput screening technique in quantitative proteomics that uses 6, 10 and 16 isotopes of labels to specifically label amino groups of peptides for tandem analysis by high-resolution mass spectrometry, allowing simultaneous comparison of protein expression between up to 16 samples.

1.        Label free proteomics

Label free protein quantification allows the relative quantification of peptides by mass spectrometric analysis of enzymatically cleaved peptides without the use of expensive stable isotope labels as internal standards, simply by analyzing the mass spectrometric data generated during large-scale protein identification and comparing the signal intensity of the corresponding peptides in different samples.