Maintenance of radiation-induced intestinal fibrosis: cellular and molecular features.

Recent advances in cell and molecular radiobiology clearly showed that tissue response to radiation injury cannot be restricted to a simple cell-killing process, but depends upon continuous and integrated pathogenic processes, involving cell differentiation and crosstalk between the various cellular components of the tissue within the extracellular matrix. Thus, the prior concept of primary cell target in which a single-cell type (whatever it's epithelial or endothelial cells) dictates the whole tissue response to radiation injury has to be replaced by the occurrence of coordinated multicellular response that may either lead to tissue recovery or to sequel development. In this context, the present review will focus on the maintenance of the radiation-induced wound healing and fibrogenic signals triggered by and through the microenvironment toward the mesenchymal cell compartment, and will highlight how sequential and sustained modifications in cell phenotypes will in cascade modify cell-to-cell interactions and tissue composition.