Characterizing the composition of bone formed during fracture healing using scanning electron microscopy techniques

Calcif Tissue Int. 2015 Jan;96(1):11-7. doi: 10.1007/s00223-014-9930-z. Epub 2014 Dec 25.

Abstract

About 5-10% of all bone fractures suffer from delayed healing, which may lead to non-union. Bone morphogenetic proteins (BMPs) can be used to induce differentiation of osteoblasts and enhance the formation of the bony callus, and bisphosphonates help to retain the newly formed callus. The aim of this study was to investigate if scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) can identify differences in the mineral composition of the newly formed bone compared to cortical bone from a non-fractured control. Moreover, we investigate whether the use of BMPs and bisphosphonates-alone or combined-may have an effect on bone mineralization and composition. Twelve male Sprague-Dawley rats at 9 weeks of age were randomly divided into four groups and treated with (A) saline, (B) BMP-7, (C) bisphosphonates (Zoledronate), and (D) BMP-7 + Zoledronate. The rats were sacrificed after 6 weeks. All samples were imaged using SEM and chemically analyzed with EDS to quantify the amount of C, N, Ca, P, O, Na, and Mg. The Ca/P ratio was the primary outcome. In the fractured samples, two areas of interest were chosen for chemical analysis with EDS: the callus and the cortical bone. In the non-fractured samples, only the cortex was analyzed. Our results showed that the element composition varied to a small extent between the callus and the cortical bone in the fractured bones. However, the Ca/P ratio did not differ significantly, suggesting that the mineralization at all sites is similar 6 weeks post-fracture in this rat model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Density Conservation Agents / therapeutic use*
  • Bone Morphogenetic Protein 7 / therapeutic use
  • Bone Morphogenetic Proteins / metabolism
  • Bone and Bones / pathology
  • Bone and Bones / ultrastructure*
  • Bony Callus / drug effects*
  • Bony Callus / pathology
  • Calcification, Physiologic / drug effects
  • Cell Differentiation / drug effects
  • Diphosphonates / therapeutic use
  • Fracture Healing / drug effects*
  • Fracture Healing / physiology
  • Fractures, Bone / drug therapy*
  • Fractures, Bone / pathology
  • Imidazoles / therapeutic use
  • Male
  • Microscopy, Electron, Scanning*
  • Rats, Sprague-Dawley
  • Zoledronic Acid

Substances

  • Bone Density Conservation Agents
  • Bone Morphogenetic Protein 7
  • Bone Morphogenetic Proteins
  • Diphosphonates
  • Imidazoles
  • Zoledronic Acid