Neoplasia following use of BMPs: is there an increased risk?

INTRODUCTION: Bone morphogenetic proteins are multi-functional growth factors, which play an important role in embryonic development and cellular functions. Among several molecules in this family, BMP-2 and BMP-7 are currently being used in the clinical setting. Main clinical targets include the treatment of non-union, open fractures and spinal fusion. Their use has not been without complications, one of which might be a carcinogenic effect. AREAS COVERED: The authors offer a comprehensive review of the existing literature on the clinical studies analysing the role of bone morphogenetic proteins (BMPs) on carcinogenesis. The authors analyse the available literature and describe potential signalling pathways that can be affected as per available experimental in vitro and in vivo models. EXPERT OPINION: The available experimental data and clinical evidence are rather inadequate to allow any safe scientific conclusions. Clinical studies provide incomplete evidence to support the hypothesis that BMPs are carcinogenic. The available literature has several limitations including incomplete documentation, unreported data and inhered bias as a large number of trials have been funded by the industry. The need of well-structured studies is essential to address these safety concerns.

Release of growth factors and the effect of age, sex, and severity of injury after long bone fracture. A preliminary report.

BACKGROUND AND PURPOSE: The systemic response after fracture is regulated by a complex mechanism involving numerous growth factors. In this study, we analyzed the kinetics of key growth factors following lower-limb long bone fracture. MATERIALS AND METHODS: Human serum was isolated from 15 patients suffering from lower-limb long bone fracture (tibia/femur) requiring surgical fixation. The levels of platelet-derived growth factor (PDGF-BB), vascular edothelial growth factor (VEGF), insulin growth factor-I (IGF-I), and transforming growth factor ß1 (TGF-ß1) were assayed by colorimetric ELISA at different time points during the first week after fracture. 10 healthy volunteers made up the control group of the study. Serum levels of the growth factors measured were compared to age, sex, and injury severity score. RESULTS: We found that there was a decline in the levels of PDGF-BB, IGF-I and TGF-ß1 during the first 3 days after fracture. However, VEGF levels remained unchanged. The levels of all the growth factors studied then increased, with the highest concentrations noted at day 7 after surgery. No correlation was found between circulating levels of growth factors and age, injury severity score (ISS), blood loss, or fluid administration. INTERPRETATION: There are systemic mitogenic and osteogenic signals after fracture. Important growth factors are released into the peripheral circulation, but early after surgery it appears that serum levels of key growth factors fall. By 7 days postoperatively, the levels had increased considerably. Our findings should be considered in cases where autologous serum is used for ex vivo expansion of mesenchymal stem cells. There should be further evaluation of the use of these molecules as biomarkers of bone union.

Do nonsteroidal anti-inflammatory drugs affect bone healing? A critical analysis.

Nonsteroidal anti-inflammatory drugs (NSAIDs) play an essential part in our approach to control pain in the posttraumatic setting. Over the last decades, several studies suggested that NSAIDs interfere with bone healing while others contradict these findings. Although their analgesic potency is well proven, clinicians remain puzzled over the potential safety issues. We have systematically reviewed the available literature, analyzing and presenting the available in vitro animal and clinical studies on this field. Our comprehensive review reveals the great diversity of the presented data in all groups of studies. Animal and in vitro studies present so conflicting data that even studies with identical parameters have opposing results. Basic science research defining the exact mechanism with which NSAIDs could interfere with bone cells and also the conduction of well-randomized prospective clinical trials are warranted. In the absence of robust clinical or scientific evidence, clinicians should treat NSAIDs as a risk factor for bone healing impairment, and their administration should be avoided in high-risk patients.

The effect of antibiotics on bone healing: current evidence.

INTRODUCTION: Bone healing is a complex cascade of events that involves the proliferation and differentiation of osteoblastic cells under the influence of signals from growth factors, cytokines and mechanical loading. Several medications have been found to interact negatively with this process including cytostatics, NSAIDs and corticosteroids; however, the effect of antibiotics on bone repair processes remains obscure. AREAS COVERED: The authors offer a comprehensive review of the existing literature on the in vivo and in vitro effect of antibiotics on bone, bone cells and fracture healing. The authors describe the pharmacokinetic characteristics of antibiotics after parenteral administration as well as their levels when applied locally together with a delivery vehicle. EXPERT OPINION: The available experimental data and clinical evidence are rather limited to allow safe conclusions. In vitro studies indicate that high doses administered after systemic administration have little or no direct effect on bone cells. Further studies are desirable to define the effect of higher or prolonged concentrations on bone biology and especially that of high concentrations released by locally implanted antibiotic-delivery systems, that is, bone cement, spacers and beads.

The effect of bone morphogenetic protein-2, bone morphogenetic protein-7, parathyroid hormone, and platelet-derived growth factor on the proliferation and osteogenic differentiation of mesenchymal stem cells derived from osteoporotic bone.

INTRODUCTION: It has been previously shown that in patients with osteoporosis, mesenchymal stem cell (MSC) growth rate and osteogenic potential is decreased contributing to inferior fracture consolidation. The aim of this study was to investigate the effect of bone morphogenetic protein-2 (BMP-2), BMP-7, parathyroid hormone (PTH), and platelet-derived growth factor (PDGF) on proliferation and osteogenic differentiation of MSCs derived from patients with osteoporosis. MATERIALS AND METHODS: Trabecular bone was obtained from 10 patients (four males, mean age 76 years) with lower extremity osteoporotic fractures. MSCs were isolated by enzymatic digestion. Functional assays of proliferation and osteogenic differentiation were performed under the influence of a wide range of concentrations of BMP-2, BMP-7, PTH, and PDGF-BB. Proliferation was assessed using CFU-F and XTT assays. Osteogenic differentiation was assessed by alkaline phosphatase activity and total calcium production. RESULTS: MSC proliferation was found to be stimulated by supplementation with BMP-7 and PDGF-BB, whereas BMP-2 and PTH had little effect. The largest increase in proliferation rate was observed after administration 100 ng/mL of BMP-7. All four molecules induced alkaline phosphatase activity and calcium production in growing osteoblasts with a dose-dependent effect noted. BMP-2 and BMP-7 at their highest studied concentration (100 ng/mL) produced a threefold increase in the osteogenic potential of MSCs. CONCLUSION: BMP-7, BMP-2, PTH, and PDGF-BB were observed to have a positive effect on osteogenic differentiation of MSCs. BMP-7 and PDGF-BB (in high doses) could be considered most potentially advantageous because they enhance both proliferation and osteogenic differentiation of MSCs derived from elderly osteoporotic bone.

Efficacy of minimally invasive techniques for enhancement of fracture healing: evidence today.

The successful treatment of nonunions represents a major challenge for orthopaedic surgeons. Lately, ongoing advances made in the field of molecular medicine and molecular biology have increased our understanding of the pathways and involvement of mediators surrounding the bone healing process. As a result, the surgeon's armamentarium has been increased in terms of options for intervention. This article aims to provide an overview of minimally invasive techniques applicable in the treatment of nonunions of fractures.

Use of high-resolution microscopy coil MRI for depicting orbital anatomy.

OBJECTIVE: High-resolution MRI (HR-MRI) is a powerful non-invasive tool that provides images of higher spatial resolution and enables visualization of tissues previously unidentified with conventional techniques. The utilization of HR-MRI in the eye and orbit is essential due to the minute structure with great tissue diversity. The purpose of this study is to investigate the use of a novel surface coil and to explore the potential of this approach to depict normal anatomy. METHODS: MR images were acquired using a commonly available 1.5T scanner. Ten normal volunteers were imaged using a surface microscopy coil of 47 mm inner diameter. T1- and T2-weighting and fat suppression techniques were used. HR-MR images were compared with conventional head coil MR images. RESULTS: Overall exquisite anatomic detail of the eye and orbit is revealed. The in-plane resolution was 312 microm and the displayed pixel dimension 156 microm. Previously unobserved distinction of the globe layers and muscle groups is possible. To our best knowledge, our group was the first to demonstrate Tenon's capsule and the tarsal plate with MRI. The ciliary body and zonules of the lens are clearly visible. The superior muscle group is illustrated, being apparently divided into its components, namely the superior rectus and the levator palpebrae superioris muscles. Finally, the retrobulbar fat and parts of its connective tissue are depicted. CONCLUSION: High-resolution microscopy coil MRI improves the image resolution dramatically and enables a detailed tissue depiction of the orbital and globe structures. Therefore, its introduction in routine clinical use can facilitate diagnosis and pre-operative planning in challenging cases.

Pharmacological agents and impairment of fracture healing: what is the evidence?

Bone healing is an extremely complex process which depends on the coordinated action of several cell lineages on a cascade of biological events, and has always been a major medical concern. The use of several drugs such as corticosteroids, chemotherapeutic agents, non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, anticoagulants and drugs which reduce osteoclastic activity have been shown to affect bone healing. This review article presents our current understanding on this topic, focusing on data illustrating the effect of these drugs on fracture healing and bone regeneration.