Automatic Quantitative Micro-Computed Tomography Evaluation of Angiogenesis in an Axially Vascularized Tissue-Engineered Bone Construct

Abstract

In this study quantitative analysis of vascularization using micro-CT along with 3D reconstruction and automatic analysis exhibit to be a powerful method superior to histological evaluation of cross sections.

Evaluation of Angiogenesis of Bioactive Glass in the Arteriovenous Loop Model

“…17 Moreover, recent studies have demonstrated axially vascularization of different bone scaffolds such as custom-made processed bovine cancellous bone matrix, particulated porous hydroxyapatite, and beta-tricalcium phosphate matrix using the AVL model. 14,15 It is known that the venous and the graft segments of the AVL are responsible for early angiogenesis up to day 14. 25 The thick tunica media of the artery was thought to avoid vascular sprouting at early stages after AVL construction.…”

“…In previous studies using a particulated porous hydroxyapatite and beta-tricalcium phosphate matrix, a predominance of neocapillaries arising from the venous part of the AVL was found at 2 weeks, whereas no further difference was detected at the 4-week explantation time point between the arterial and venous AVL segments. 15 We determined the vascular network both histologically and by microcomputed tomography. Histology can evaluate a limited number of 2D cross sections and therefore yields a 2D approximation, while mCT offers the opportunity to reconstruct and morphometrically evaluate the vascular network of the entire specimen.…”

“…29 Recently, we were able to show an increased neovascularization in the AVL model by the use of fibrin gelimmobilized VEGF 165 and basic fibroblast growth factor (bFGF). 15,17 The incorporation of 45S5 Bioglass Ò should lead to increased secretion of VEGF in vitro and increased neovascularization in vivo, as documented in the literature. 30 In a recent investigation, we were able to prove the possible combination of the intrinsic AVL model with an extrinsic vascular pathway using a newly developed porous titanium chamber to allow additional extrinsic vascularization of scaffolds via incorporated pores in the chamber design.…”

“…13 Recently, our group managed to vascularize different bone scaffolds using this arteriovenous loop (AVL) model. 14,15 We also evaluated different angiogenic growth factors in this AVL model to enhance angiogenesis, and we were able to show an increased survival of osteoblasts in this model compared to extrinsic vascularized scaffolds. [16][17][18] 45S5 Bioglass Ò has been used to develop bone tissue scaffolds, and the effects of Bioglass Ò dissolution products to support angiogenesis by secretion of vascular endothelial growth factor (VEGF) have been reported.…”

Imaging Strategies for Tissue Engineering Applications

“…One study evaluated the vascular ingrowth within a gel system consisting of an arteriovenous loop placed in a particulated porous hydroxyapatite and btricalcium phosphate matrix with and without incorporation of exogenous growth factors. 25 Micro-CT analysis was performed with Microfil contrast enhancement to visualize the 3D geometry of the vascular tree within the construct (Fig. 3B), allowing for easy and accurate quantification compared to 2D histological analysis.…”