We believe that late effects of radiation are not strictly caused by stem cell depopulation and that late effects such as progressive ischemia and fibrosis may be preventable by appropriate manipulations of growth factors and other chronic cytokine expression. We have shown that various deleterious cytokines (TNF, TGFbeta) cause late effects including fibrovascular damage. Other "beneficial" cytokines can prevent unwanted apoptosis, cytokine induced inflammation and vascular damage. We will try to clarify the role cytokines and chronic inflammation have on the production of radiation complications.