In vitro assay of extracellular matrix elastin degradation

This report describes a method for determining specifically and sensitively the degradation of the elastin component within complicated extracellular matrices in vitro. Extracellular matrices rich in elastin were metabolically labeled with [3H]lysine during 3 week cultures of smooth muscle cells under ascorbate-free conditions in vitro. Elastin was quantitated on the basis of labeled desmosine/isodesmosine in the matrices as determined by a cation-exchange HPLC program utilizing a Beckman 6300 amino acid analyzer. The net loss of desmosine/isodesmosine during co-culture of human macrophages with the matrices was then used to assay cellular elastin degradation. This method allows for the production of reproducibly labeled matrices and compares favorably with previously described techniques of elastin degradation by live cells in vitro.