Multifunctional biomaterials from the sea: Assessing the effects of chitosan incorporation into collagen scaffolds on mechanical and biological functionality.

UNLABELLED: Natural biomaterials such as collagen show promise in tissue engineering applications due to their inherent bioactivity. The main limitation of collagen is its low mechanical strength and somewhat unpredictable and rapid degradation rate; however, combining collagen with another material, such as chitosan, can reinforce the scaffold mechanically and may improve the rate of degradation. Additionally, the high cost and the risk of prion transmission associated with mammal-derived collagen has prompted research into alternative sources such as marine-origin collagen. In this context, the overall goal of this study was to determine if the incorporation of chitosan into collagen scaffolds could improve the mechanical and biological properties of the scaffold. In addition the study assessed if collagen, derived from salmon skin (marine), can provide an alternative to collagen derived from bovine tendon (mammal) for tissue engineering applications. Scaffold architecture and mechanical properties were assessed as well as their ability to support mesenchymal stem cell growth and differentiation. Overall, the addition of chitosan to bovine and salmon skin-derived collagen scaffolds improved the mechanical properties, increasing the compressive strength, swelling ratio and prolonged the degradation rate. Mesenchymal stem cell (MSC) attachment and proliferation was most improved on the bovine-derived collagen scaffold containing a 75:25 ratio of collagen:chitosan, and when MSC osteogenic and chondrogenic potential on the scaffold was assessed, a significant increase in calcium production (p<0.001) and sulfated glycosaminoglycan (sGAG) production (p<0.001) was observed respectively. Regardless of chitosan content, the bovine-derived collagen scaffolds out-performed the salmon skin-derived collagen scaffolds, displaying a larger pore size and higher percentage porosity, more regular architecture, higher compressive modulus, a greater capacity for water uptake and allowed for more MSC proliferation and differentiation. This versatile scaffold incorporating the marine biomaterial chitosan show great potential as appropriate platforms for promoting orthopaedic tissue repair while the use of salmon skin-derived collagen may be more suitable in the repair of soft tissues such as skin. STATEMENT OF SIGNIFICANCE: Collagen is commonly used in tissue engineering due to its biocompatibility; however, it has low mechanical strength and an unpredictable degradation rate. In addition, high cost and risk of prion transmission associated with mammalian-derived collagen has prompted research into alternative collagen sources, namely, marine-derived collagen. In this study, scaffolds made from salmon-skin collagen were compared to the more commonly used bovine-derived collagen with a focus on orthopaedic applications. To improve the mechanical properties of these scaffolds, another marine biomaterial, chitosan, was added to produce scaffolds with increased mechanical stability. The collagen-chitosan composites were also shown to support mesenchymal stem cell differentiation towards both bone and cartilage tissue. This multi-functional scaffold therefore has potential in both bone and cartilage regeneration applications.