Table 2.

Selected growth factors and their functions in fracture healing [34], [57], [183].

	Source	Receptors class/target cells	Functions	Clinical applications in orthopaedics
BMPs	Osteoprogenitor cells, osteoblasts, bone extracellular matrix	Serine/threonine kinase receptors, stem cell and chondrocyte	Promotes differentiation of mesenchymal stem cells/ osteoprogenitor cells into chondrocytes and osteoblasts, influences skeletal pattern formation	rhBMP-2 is used for the treatment of anterior lumbar spinal fusion and open tibial fractures, and rhBMP-7 is used for posterolateral lumbar spine fusion
FGFs	Macrophage, mesenchymal cells, chondrocytes, osteoblasts	Tyrosine kinase receptors	Mitogenic for mesenchymal stem cells, chondrocytes, and osteoblasts. Increases collagen deposition and angiogenesis [57]
VEGF	Platelets, chondrocytes in callus	Vascular endothelial cells	Increases angiogenesis and vascular development
PTH	Parathyroid glands	Stem cell, chondrocyte and osteoblast	Increased callus size, bone mass and mineral content	The full length PTH(1–84) and a segment, PTH(1–34), is used to increase the cancellous bone mass and reduce the risk of vertebral and non-vertebral fracture of patients with osteoporosis
PRP	blood	Variety cell types	Cocktail of growth factors	Mainly applied in orthopaedics and sports medicine to help hemostasis and musculoskeletal healing [184]

Abbreviations: BMPs, bone morphogenetic proteins; FGFs, fibroblast growth factors; VEGF, vascular endothelial growth factor; (rh)PTH, (recombinant human)parathyroid hormone; PRP, platelet-rich plasma.