Email updates

Keep up to date with the latest news and content from BMC Research Notes and BioMed Central.

Open Access Technical Note

Quantification of active and total transforming growth factor-β levels in serum and solid organ tissues by bioassay

Shaukat A Khan1, Jennifer Joyce1 and Takeshi Tsuda12*

Author affiliations

1 Nemours Biomedical Research, Alfred I. duPont Hospital for Children, 1600 Rockland Rd, Wilmington, DE, 19803, USA

2 Nemours Cardiac Center, Alfred I. duPont Hospital for Children, 1600 Rockland Rd, Wilmington, DE, 19803, USA

For all author emails, please log on.

Citation and License

BMC Research Notes 2012, 5:636  doi:10.1186/1756-0500-5-636

Published: 14 November 2012

Abstract

Background

Transforming growth factor-β (TGF-β) is a multi-factorial peptide growth factor that has a vital role in the regulation of cell growth, differentiation, inflammation, and tissue repair. Quantification of biologically active TGF-β levels in tissues is crucial to illustrate mechanisms involved in various physiological and pathological processes, but direct measurement of bioactive TGF-β level in the tissue has been hampered by lack of reliable methods. Here, we introduced mink lung epithelial cell bioassay to quantify both active and total TGF-β levels in serum and protein lysates from solid organs in the mouse model.

Findings

Mink lung epithelial cells were stably transfected with plasminogen activator inhibitor-1 promoter/luciferase construct, in which bioactive TGF-β level was represented by luciferase activity. Serum total TGF-β levels were comparable between the bioassay and enzyme-linked immunosorbent assay (ELISA), but active TGF-β levels measured by ELISA were significantly lower than those obtained by the bioassay. Active and total TGF-β levels in the solid organs including heart, liver, and kidney were also measured. Total TGF-β levels were relatively comparable among these organs, but active TGF-β levels were slightly higher in hearts and kidneys than in livers. Positive luciferase activities in the bioassay were almost completely inhibited by adding pan-TGF-β neutralizing antibodies, suggesting its high specificity to bioactive TGF-β. We also measured myocardial TGF-β levels after myocardial infarction and sham control by the bioassay, and compared the values with those obtained by ELISA. The bioassay demonstrated that both active and total tissue TGF-β levels were significantly higher in post-myocardial infarction than in sham myocardium. ELISA was markedly less sensitive in detecting both active and total TGF-β levels than our bioassay and failed to show any statistically significant difference in TGF-β levels between myocardial infarction and sham myocardium.

Conclusions

Our data suggested that the bioassay was significantly more sensitive than ELISA in detecting active TGF-β in serum and both active and total TGF-β in solid organ tissues. The bioassay will be useful in investigating TGF-β profile in various solid organs in physiological and pathological conditions.

Keywords:
Transforming growth factor-β (TGF-β); Βioassay; Plasminogen activator inhibitor-1; Mink lung epithelial cells; Enzyme-linked immunosorbent assay (ELISA); Myocardial infarction; Ventricular remodeling; Biomarker