Growth Factor
A naturally occurring peptide or protein that stimulates cellular growth, proliferation, and differentiation. Key growth factors include IGF-1, EGF, VEGF, BDNF, PDGF, FGF, and TGF-β. Many peptide drugs work by stimulating or modulating growth factor pathways.
Technical Context
Growth factors are polypeptides that regulate cell proliferation, differentiation, migration, and survival by binding to specific cell surface receptors (predominantly receptor tyrosine kinases). Major families relevant to peptide therapeutics: EGF family (EGF, TGF-α — keratinocyte proliferation, wound re-epithelialisation), FGF family (22 members — fibroblast proliferation, angiogenesis, bone development; FGFR3 is the achondroplasia target), PDGF family (fibroblast recruitment, proliferation — becaplermin is recombinant PDGF-BB approved for diabetic ulcers), VEGF family (angiogenesis — critical for wound healing and tumour vascularisation), TGF-β superfamily (TGF-β1/2/3, BMPs, activins — fibrosis, bone formation, immune regulation), IGF family (IGF-1, IGF-2 — growth, anabolism), and NGF/BDNF/GDNF (neurotrophic support). Growth factors typically act through autocrine (on self), paracrine (on nearby cells), and endocrine (via bloodstream) signalling modes.