In Vitro Effects of Combined and Sequential Bone Morphogenetic Protein Administration

Abstract

Objective: To assess the effects of combined and sequential administration of bone morphogenetic protein 2 (BMP-2) and BMP-7 on osteoblastic differentiation compared with administration of single growth factors.Design: In vitro study of osseous differentiation in murine pluripotent cells using assays of extracellular matrix calcification, alkaline phosphatase activity, and expression of osseous markers. Mesenchymal cells were cultured with BMP-2, BMP-7, or a combination of these growth factors or were sequentially exposed to the growth factors.Results: Sequential administration of BMP-2 and BMP-7 resulted in increased extracellular matrix calcification and expression of osteocalcin, whereas all groups treated with BMP up-regulated expression of the osteoblastic transcription factor Runx2/cbfa1, type I collagen, and the inhibitory BMP second messenger Smad6. None of the experimental groups demonstrated increased expression of osteopontin or Smad1, and only cells treated with concurrent administration of BMP-2 and BMP-7 increased Smad5 expression. Alkaline phosphatase activity was increased from baseline only in cells treated with BMP-2 alone.Conclusions: Culture with BMP-2 and BMP-7, their sequential administration, and their coadministration had variable effects on osseous differentiation in mesenchymal cells. These results demonstrate the need for increased understanding of the role of growth factors and their combinations in bone development and have important implications for the ongoing development of osteoinductive therapies.Arch Facial Plast Surg. 2007;9(4):242-247

Bone morphogenetic proteins 2, 5, and 6 in combination stimulate osteoblasts but not osteoclasts in vitro

“…The combination of all three BMPs significantly increased the expression of collagen type 1, although this increase was also seen with BMP-2 alone. 9 The combination also had the greatest effect on runx2 and osterix expression.…”

“…BMP-5 and BMP- 6 have not yet been examined in this setting. 9 The in vivo effect of BMP-5 and its role in bone formation were recently investigated. As the growth of long bones and certain stages of fracture healing occur by endochondral bone formation, these studies suggest that BMP-5 plays an important role in regulating the cellular activity involved in the bone remodeling process.…”

“…9,10,40 The cell cultures used in our study constitute a mixed population of different cell types and stages of differentiation to mimic in vivo cell populations. Nevertheless, bone formation is a complex process that may occur through endochondral or intramembraneous ossification preceded by bone resorption.…”

“…Few studies have addressed the combined effects of BMPs on osteogenesis, mainly focusing on BMP-2 and BMP-7. 9,10 We showed that BMP-2, BMP-5, and BMP-6 alone have distinct and diverse effects on osteoclasts and osteoblasts in vitro. 8 The aim of the present study was to investigate the effects of the simultaneous use of BMP-2, BMP-5, and BMP-6 on osteoblast and osteoclast generation to test the hypothesis that BMPs in combination exert synergistic effects on processes of bone regeneration.…”

Effects of a Mixture of Growth Factors and Proteins on the Development of the Osteogenic Phenotype in Human Alveolar Bone Cell Cultures

“…In bone tissue, therapies with GFs have been applied to promote, and in some cases to induce, desirable amounts of new bone formation in bone defects, in sites of fracture healing, and adjacent to metal implant devices (Bessho et al 1999;Ramoshebi et al 2002;Schliephake 2002;Kloen et al 2003). Considering that in the body, cells are exposed to diverse GFs simultaneously, ideally any therapy should involve a mixture of GFs with similarities to those implicated in bone tissue healing (Cheifetz et al 1996;Roethy et al 2001;Raiche and Puleo 2004;Arosarena and Puleo 2007). Indeed, a well-known therapy with GFs for bone defects is the application of autologous platelet-rich plasma (PRP) (Marx et al 1998;Dugrillon et al 2002;reviewed in Anitua et al 2007b), a concentrate of platelets in plasma.…”