Coordinate expression of the insulin-like growth factor system after microembolisation in porcine heart

Abstract

Objectives: Coronary microembolisation in the pig heart induces angiogenesis in a model of sterile inflammation due to focal necrosis. We have recently shown in this model that insulin-like growth factor I (IGF-I) is involved in inflammation-linked angiogenic processes due to its enhanced transcription after 72 h of ischaemia by infiltrating monocytes in areas of microsphere-induced focal necrosis where capillary sprouting could be detected. To obtain further insights into this process we studied by means of Northern blot analysis and in situ hybridisation the gene expression of other members of the IGF family, i.e. the six IGF binding proteins (IGFBPs), the insulin receptor, and the type I IGF receptor. Methods: Myocardial injury was induced by injection of 25 μm non-radioactive microspheres into the left circumflex artery (LCx) in pigs that were killed after 3–24, 72, or 168 h of microembolisation. Tissue was collected from a non-ischaemic control area and the LCx region of the same heart for further analysis. Results: We found decreased IGFBP-5 (2.7-fold; PPConclusion: These results indicate a coordinate gene expression of the IGF system in microembolised porcine myocardium, compatible with a role of IGF-I, IGFBP-3, IGFBP-5, and IGFBP-6 in inflammation-linked angiogenesis and/or repair processes.