Growth Factors


 * A growth factor is an naturally occurring protein capable of stimulating cellular proliferation and differentiation
 * Bone morphogenic proteins stimulate stem cell differentiation into bone cells, while vascular endothelial growth factors stimulate endothelial proliferation
 * Growth factors govern tissue formation and organization
 * Important in regulating a variety of cellular processes such as adhesion, migration, and proliferation
 * Often promote cell differentiation and maturation, which varies between growth factors
 * Stored in ECM through specific binding with glycosaminoglycans (e.g. heparins), and can elicit their biological activity once released
 * Carboxyl groups in GAGs and amine groups in the growth factors bond to eachother electrostatically
 * Typically act as signaling molecules between cells and cell-ECM

Angiogenic Growth Factors

 * Angiogenesis is a physiological process involving the growth of new blood vessels
 * Angiogenesis is critical for tissue construct survival in vivo
 * When engineered tissues are implanted in vivo, they need sufficient nutrients and oxygen to survive, which can be provided by blood vessels
 * It is neccessary to quickly induce blood vessel formation after implantation of the engineered tissue (one of the biggest challenges in tissue engineering)
 * Angiogenic growth factors are naturally occurring compounds that stimulate blood vessel growth
 * FGF - Promotes proliferation & differentiation of endothelial cells, smooth muscle cells, and fibroblasts
 * Fibroblast growth factor
 * bFGF or FGF2 is used widely in tissue engineering
 * VEGF - Promotes proliferation of endothelial cells
 * Vascular endothelial growth factor
 * PDGF - Recruit smooth muscle cells
 * When engineering blood vessels endothelial cell formation is vital
 * If there is no layer of endothelial cells then clotting will occur, which will eventually lead to a heart attack or stroke

Stem Cells and Growth Factors

 * Embryonic stem cell differentiation is affected by the activity of a number of cellular signals such as growth factors
 * Growth factors guide mesenchymal stem cell (MSC) differentiation
 * TGF-β (transforming growth factor β)
 * FGF-2 (fibroblast growth factor 2)
 * BMP (bone morphogenetic protein)
 * EGF (epithelial growth factor)
 * How to induce Chondrogenesis
 * MSC+TGF-β+FGF-2+ascorbic acid
 * How to induce Osteogenesis
 * MSC+BMP
 * MSC+EGF