Dry versus hydrated collagen scaffolds: are dry states representative of hydrated states?

AbstractIntroductionCollagen composite scaffolds have been used for a number of studies in tissue engineering. The hydration of such highly-porous and hydrophilic structures may influence mechanical behaviour and porosity due... [ view full abstract ]

Abstract

Introduction

Collagen composite scaffolds have been used for a number of studies in tissue engineering. The hydration of such highly-porous and hydrophilic structures may influence mechanical behaviour and porosity due to swelling. The differences in physical properties following hydration would represent a significant limiting factor for the seeding, growth and differentiation of cells in vitro and the overall applicability of such hydrophilic materials in vivo.

The aim of the present work, however, is to describe the study of the influence of eight differing scaffold material compositions, focusing on collagen content and their final properties such as internal structure, porosity and mechanical properties in both the dry and hydrated states. It was anticipated that the differences in physical properties following hydration would represent a significant limiting factor for the seeding, growth and differentiation of mesenchymal stem cells and the overall applicability of such hydrophilic materials.

Methods

Scaffolds based on collagen matrix, poly(DL-lactide) nanofibers, calcium phosphate particles and sodium hyaluronate with 8 different material compositions were characterized in the dry and hydrated states using X-ray micro-computed tomography, compression tests, hydraulic permeability measurement, degradation tests and infrared spectrometry.

Results

Hydration, simulating the conditions of cell seeding and cultivation up to 48 hours and 576 hours, was found to exert a minor effect on the morphological parameters and permeability. Conversely, hydration had a major statistically significant effect on the mechanical behaviour of all the tested scaffolds. The elastic modulus and compressive strength of all the scaffolds decreased by approx. 95%. The quantitative results provided confirm the importance of analysing scaffolds in the hydrated rather than the dry state since the former more precisely simulates the real environment for which such materials are designed. The measurement of scaffolds in the dry state is, however, useful regarding to the basic characterisation of the selection of preparation methods; however, it is important that real conditions not be neglected, especially with concern to hydrophilic polymers.

Acknowledgements

This study was supported by a grant project awarded by the Ministry of Health of the Czech Republic (15-25813A).