Characterization of Collagen Metabolism in Normal and Chronic Obstructive Pulmonary Diseased Human Lung Fibroblasts Reared in Serum‐free Medium

Abstract

The structural integrity of the human lung is maintained by a healthy extracellular matrix (ECM). One of the main components, collagen type I is produced by fibroblasts and provides strength and structure to the cells and the function of the lung. A careful balance of collagen degradation and production is controlled by matrix metalloproteases (MMPs). In diseased states such as Chronic Obstructive Pulmonary Disease (COPD), two collagenases, MMP‐8 and MMP‐12, are upregulated. In this study we measure collagen metabolism of human lung fibroblasts (HLFs) reared in serum‐free media (subconfluent normal (NHLF) and COPD diseased (DHLF)). Commercially available early passage human lung fibroblasts established from lung tissue, obtained during biopsy, were cultured and passaged in our laboratory through P4 and P5 for both the NHLF and DHLF. Both normal and diseased HLF cells were viable when cultured at subconfluence for 24 hours in serum free medium. They produced detectable quantities of intact collagen type I secreted and incorporated in the ECM. The amount of intact collagen decreased between passage 4 and 5 (p<0.01) in both cell types indicating there is a limit to the passages that can be utilized to measure ECM alterations. Degraded collagen type I was present in the cell layer fractions of both cell types, but was 10 fold higher in the cell layer of diseased HLF cells. This indicates that the expected ECM profile of diseased HLF can be demonstrated in serum‐free culture. Both cell types produced detectable levels of MMP‐8 and MMP‐12 collagenases. In this study we have demonstrated that normal and diseased HLF can be cultured in serum‐free conditions while maintaining their metabolic profile. The production of MMPs and collagens provides an experimental system in which we can test potential therapeutics that may alter the fibrotic response during COPD. Support or Funding Information This work is supported by a grant from the PCOM Alumni and the Division of Research at PCOM.