Collagen-containing sutures for wound closure

Abstract

This thesis investigates the properties and biomedical applications of collagen-containing surgical sutures, with a focus on their potential to enhance wound healing. Collagen, an abundant natural biopolymer in the extracellular matrix, is known for its biocompatibility, biodegradability, and low immunogenicity. It is also known for its contribution in each phase of tissue repair: haemostasis, inflammation, proliferation, and remodelling. Rapid degradation and limited mechanical strength limit the use of pure collagen, which calls for the use of composite materials.

Sutures are materials used for wound closure, categorized by absorbability (absorbable or non-absorbable) and material origin (natural or synthetic). While absorbable sutures degrade over time and non-absorbable sutures require removal or remain in the body, both have limitations. To overcome these limitations, sutures can be modified by incorporating bioactive agents such as collagen, either onto the surface as a coating or integrated within the fibre. Fabrication methods for modified sutures include dipping/coating, melt-spinning, and electrospinning. Incorporating collagen, particularly using a synthetic base with better mechanical properties, aims to combine structural support with biological activity.

The study explores the incorporation of collagen into/onto absorbable suture materials to improve tissue regeneration and reduce inflammatory responses. A comparative analysis was conducted between traditional synthetic sutures and collagen-enhanced variants, examining parameters such as tensile strength, degradation rate, and biological compatibility. In vitro studies showed that denatured collagen-coated PE/PEE sutures significantly enhanced adhesion and proliferation of human osteoblasts and tenocytes compared to uncoated sutures, especially when knotted and subjected to abrasion. Denatured collagen coating also promoted alkaline phosphatase activity, a marker for bone mineralization. In vivo studies using rat and mouse models demonstrated beneficial outcomes. A study on rat Achilles tendon repair found that atelocollagen-coated Vicryl resulted in improved load to failure at 6 weeks post-operation compared to standard Vicryl and DOPA-coated Vicryl, along with lower modified Bonar scores (indicating more normal histology) at both 1 and 6 weeks. The collagen coating also appeared to influence early collagen synthesis and organization, resulting in larger fibril diameters at week 1. Another study in a mouse acute incision wound healing model showed that electrospun PCL@COL sutures degraded slower than Vicryl or PCL and significantly accelerated wound closure efficacy. PCL@COL sutures demonstrated the highest mean collagen deposition density and increased formation of new blood vessels. While the findings indicate that collagen-containing sutures demonstrate favourable mechanical properties and enhanced biological activity, the study was limited by a relatively small number of experimental samples, which may affect the generalizability of the results.

However, the research supports the potential of collagen-based sutures as promising alternatives in surgical practice, particularly for wounds that are prone to infections, and for cosmetic scars.