Accelerating isotope dilution LC-MS-based desmosine quantification for estimating elastin turnover

Circulating total desmosine, representing endogenous systemic elastin degradation activity, is an emerging biomarker for mortality risk in several diseases and aging. However, the existing analytical method takes more than 23 hours to complete, limiting its potential applications. The objective of this study was to shorten the turnover time of a stable isotope dilution liquid chromatogram mass spectrometry-based desmosine assay. Plasma samples were analyzed using acid hydrolysis followed by solid-phase extraction and LC-MS. Two approaches to reduce assay time were tested: microwave-assisted acid hydrolysis and direct injection following solid-phase extraction. The combination of acid hydrolysis at 180°C for 8 minutes and a low-volume elution design for solid-phase extraction reduced the overall assay time to ~ 30 minutes. The assay was validated with intra-day precision and accuracy ranging from 4% to 14%, and −7% to 9%, respectively, while inter-day precision and accuracy were 0% to 9% and 1% to 3%, respectively. The assay was tested in a cohort of patients with acute aortic dissection and control subjects, where desmosine concentrations were approximately three-fold higher in patients. These results demonstrated that rapid desmosine analysis can be achieved with the use of both microwave-assisted hydrolysis and streamlined solid-phase extraction.