"In particular aspects, the agent is a chemical, a drug, a proteinaceous molecule, a nucleic acid, a lipid, an antibody, an antigen, a hormone, a nutritional substance, a cell or a combination thereof In certain aspects, the hormone is a growth factor, including but not limited to transforming growth factor beta, basic fibroblast growth factor, epidermal growth factor, vascular endothelial growth f" . . . .