Cancellous Bone Properties and Matrix Content of TGF-β2 and IGF-I in Human Tibia: A Pilot Study

Abstract

Transforming and insulin-like growth factors are important in regulating bone mass. Thus, one would anticipate correlations between matrix concentrations of growth factors and functional properties of bone. We therefore investigated the relationships of (1) TGF-b2 and (2) IGF-I matrix concentrations with the trabecular microstructure, stress distribution, and mechanical properties of tibial cancellous bone from six male human cadavers. Trabecular stress amplification (VMExp/r app ) and variability (VMCOV) were calculated using microcomputed tomography (lCT)-based finite element simulations. Bone volume fraction (BV/TV), surface/volume ratio (BS/BV), trabecular thickness (Tb.Th), number (Tb.N) and separation (Tb.Sp), connectivity (Eu.N), and anisotropy (DA) were measured using 3-D morphometry. Bone stiffness and strength were measured by mechanical testing. Matrix concentrations of TGF-b2 and IGF-I were measured by ELISA. We found higher matrix concentrations of TGF-b2 were associated with higher Tb.Sp and VMExp/r app for pooled data and within subjects. Similarly, a higher matrix concentration of IGF-I was associated with lower stiffness, strength, BV/TV and Tb.Th and with higher BS/BV, Tb.Sp, VMExp/r app and VMCOV for pooled data and within subjects. IGF-I and Tb.N were negatively associated within subjects. It appears variations of the stress distribution in cancellous bone correlate with the variation of the concentrations of TGF-b2 and IGF-I in bone matrix: increased local matrix concentrations of growth factors are associated with poor biomechanical and architectural properties of tibial cancellous bone.

The Measurement of Bone Quality Using Gray Level Co-Occurrence Matrix Textural Features

“…Three crucial parameters were obtained from the bone specimens: elastic modulus, strength; and bone volume fraction (BV/TV). The Micro-CT image data and mechanical test data were obtained from previous studies 6, 8 .…”

“…Chappard 5 uses run-length distribution texture analysis methods on X-ray radiographs to prove that it is a reliable descriptor of bone loss in a rat bone model. Recent studies also indicate that Markov Random Field based models such as semivariograms are capable of assessing bone characteristic properties 6–8 . The Trabecular Bone Score (TBS) has gained the attention of researchers in the assessment of fracture risk 9, 10 .…”

Biomechanical properties and microarchitecture parameters of trabecular bone are correlated with stochastic measures of 2D projection images

“…3D Micro-CT images of trabecular bone specimens and their microarchitecture parameters were obtained from previous studies [31, 32]. Fifteen cylindrical specimens of trabecular bone with a diameter of 8 mm and a height of 10 mm were cored from the proximal tibias of six male human cadavers (48 ± 14 years old) that were free of bone diseases.…”

“…These trabecular bone specimens were scanned by a high resolution Micro-CT system following established techniques [33, 34]. Raw images of trabecular bone specimens were reconstructed to produce 3D Micro-CT images with a voxel size of 50 m. A custom-written program was used to compute microarchitecture parameters from 3D Micro-CT images [32]. Bone volume fraction (BV/TV), bone surface-to-volume ratio (BS/BV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp) were calculated using stereology principles [35].…”

Capacidade osteorregenerativa da elastina, hidroxiapatita e proteí­na morfogenética óssea no tratamento de defeitos femorais em ratos

“…Os fatores de crescimento beta (TGF-) pertencem a grande família de fatores de crescimento e de diferenciação incluindo as proteínas morfogenéticas do osso, fator de crescimento transformador beta, fatores de diferenciação do crescimento (GDF), activinas e inibinas. Pelo menos trinta e quatro membros desta linhagem foram identificados no genoma humano (DIMITRIOU;GROSS, 2012;KURIEN;PEARSON;SCAMMELL, 2013;LIEBERMAN;DALUISKI;EINHORN, 2002;YENI et al, 2009).…”