The Effect of Pore Directionality of Collagen Scaffolds on Cell Differentiation and In Vivo Osteogenesis.

Miguelangel Moncayo-Donoso,Rick Visser,Diego A Garzón-Alvarado,José Becerra,Gustavo A Rico-Llanos,Marta R Fontanilla

doi:10.3390/polym13183187

Abstract

Although many bone substitutes have been designed and produced, the development of bone tissue engineering products that mimic the microstructural characteristics of native bone remains challenging. It has been shown that pore orientation within collagen scaffolds influences bone matrix formation by the endochondral route. In addition, that the unidirectional orientation of the scaffolds can limit the growth of blood vessels. However, a comparison between the amount of bone that can be formed in scaffolds with different pore orientations in addition to analyzing the effect of loading osteogenic and proangiogenic factors is still required. In this work we fabricated uni- and multidirectional collagen sponges and evaluated their microstructural, physicochemical, mechanical and biological characteristics. Although the porosity and average pore size of the uni- and multidirectional scaffolds was similar (94.5% vs. 97.1% and 260 µm vs. 269 µm, respectively) the unidirectional sponges had a higher tensile strength, Young’s modulus and capacity to uptake liquids than the multidirectional ones (0.271 MPa vs. 0.478 MPa, 9.623 MPa vs. 3.426 MPa and 8000% mass gain vs. 4000%, respectively). Culturing of rat bone marrow mesenchymal stem cells demonstrated that these scaffolds support cell growth and osteoblastic differentiation in the presence of BMP-2 in vitro, although the pore orientation somehow affected cell attachment and differentiation. The evaluation of the ability of the scaffolds to support bone growth when loaded with BMP-2 or BMP-2 + VEGF in an ectopic rat model showed that they both supported bone formation. Histological analysis and quantification of mineralized matrix revealed that the pore orientation of the collagen scaffolds influenced the osteogenic process.

Highlights

IntroductionTissue engineering is a field that has become increasingly important in biomedicine during the last decades and has been dedicated to the design of better and more sophisticated biomaterials for a great variety of applications [5,6]
Since it has been well described that the osteogenic activity of bone morphogenetic proteins can be synergistically promoted by angiogenic factors such as VEGF [16,17,18], we evaluated the ability of these scaffolds to guide bone growth when loaded with BMP-2 or BMP-2 and VEGF in a rat ectopic model, as well as the effect that the implanted UC and MC scaffolds had on the amount of bone matrix formed
We found that the directionality of the pores within collagen type I scaffolds influenced their mechanical properties, as the UC sponges had a higher tensile strength and modulus of elasticity

Summary

Introduction

Tissue engineering is a field that has become increasingly important in biomedicine during the last decades and has been dedicated to the design of better and more sophisticated biomaterials for a great variety of applications [5,6]. In this context, the production of 3D porous scaffolds with significant similarity to the natural bone matrix has been a challenge for BTE researchers [7,8]

Methods

Results

Discussion

Conclusion