Synthetic collagen fascicles for the regeneration of tendon tissue.

The structure of an ideal scaffold for tendon regeneration must be designed to provide a mechanical, structural and chemotactic microenvironment for native cellular activity to synthesize functional (i.e. load bearing) tissue. Collagen fibre scaffolds for this application have shown some promise to date, although the microstructural control required to mimic the native tendon environment has yet to be achieved allowing for minimal control of critical in vivo properties such as degradation rate and mass transport. In this report we describe the fabrication of a novel multi-fibre collagen fascicle structure, based on type-I collagen with failure stress of 25-49 MPa, approximating the strength and structure of native tendon tissue. We demonstrate a microscopic fabrication process based on the automated assembly of type-I collagen fibres with the ability to produce a controllable fascicle-like, structural motif allowing variable numbers of fibres per fascicle. We have confirmed that the resulting post-fabrication type-I collagen structure retains the essential phase behaviour, alignment and spectral characteristics of aligned native type-I collagen. We have also shown that both ovine tendon fibroblasts and human white blood cells in whole blood readily infiltrate the matrix on a macroscopic scale and that these cells adhere to the fibre surface after seven days in culture. The study has indicated that the synthetic collagen fascicle system may be a suitable biomaterial scaffold to provide a rationally designed implantable matrix material to mediate tendon repair and regeneration.

Regeneration and repair of tendon and ligament tissue using collagen fibre biomaterials.

Collagen fibres are ubiquitous macromolecular assemblies in nature, providing the structures that support tensile mechanical loads within the human body. Aligned type I collagen fibres are the primary structural motif for tendon and ligament, and therefore biomaterials based on these structures are considered promising candidates for mediating regeneration of these tissues. However, despite considerable investigation, there remains no collagen-fibre-based biomaterial that has undergone clinical evaluation for this application. Recent research in this area has significantly enhanced our understanding of these complex and challenging biomaterials, and is reinvigorating interest in the development of such structures to recapitulate mechanical function. In this review we describe the progress to date towards a ligament or tendon regeneration template based on collagen fibre scaffolds. We highlight reports of particular relevance to the development of the underlying biomaterials science in this area. In addition, the potential for tailoring and manipulating the interactions between collagen fibres and biological systems, as hybrid biomaterial-biological ensembles, is discussed in the context of developing novel tissue engineering strategies for tendon and ligament.

Using small angle X-ray scattering to investigate the variation in composition across a graduated region within an intervertebral disc prosthesis.

The CAdisc-L is a polycarbonate urethane lumbar intervertebral disc prosthesis that aims to replicate the mechanical properties of a natural disc as closely as possible. In this work, Small Angle X-ray Scattering (SAXS) was used to investigate the variation in composition across prototype disc samples containing annulus and nucleus regions separated by a graduated region. An empirical data analysis method was developed involving the calculation of intensity ratios, since the SAXS data did not readily fit any of the standard analysis models. Calibration samples were used to quantify the variation in SAXS response with composition and a linescan method was employed to ascertain the change in composition across discs manufactured with different graduated region volumes. The graduated region width increases with the volume incorporated into it during manufacture, as expected, but the properties do not vary linearly across the graduated regions. The method developed during this work can be adapted for use with any series of polymer samples that shows a systematic variation in SAXS behaviour with composition.