UP-REGULATION OF IGF-I AND COLLAGEN-I MESSENGER-RNA IN HUMAN ATHEROSCLEROTIC TISSUE IS NOT ACCOMPANIED BY CHANGES IN TYPE-1 IGF RECEPTOR ORCOLLAGEN-III MESSENGER-RNA - AN IN-SITU HYBRIDIZATION STUDY

Background Immunoreactive insulin-like growth factor-1 (IGF-I) has rec ently been localized to vascular smooth muscle cells in coronary ather ectomy plaques, but it remains unclear whether these cells are the sou rce of this growth factor. We therefore investigated the gene expressi on of this factor, and the expression of the genes for its receptor an d two types of collagen known to be regulated by IGF-I, in vascular ti ssue samples from patients with atherosclerosis or restenosis. Methods Gene expression and localization were investigated by in situ hybridi zation, using S-35-labelled complementary RNA probes specific for IGF- I, its type 1 receptor, collagen I, and collagen III, The cellular com position of the tissue samples was determined by immunohistochemistry using antibodies specific for smooth muscle cells and macrophages. Res ults IGF-I and collagen I messenger RNAs were found in areas containin g smooth muscle cells and macrophages, but collagen III and type 1 IGF receptor gene expression could not be detected in any tissue samples. Conclusion IGF-I appears to be involved in the progression of the ath erosclerotic plaque, even at an advanced stage, but preliminary data f rom two restenotic plaques indicate that it may not be involved in the later stages of restenosis.