Bio-Composites Based on Unique Soft Coral Collagen Fibers Towards Tissue Engineered Blood Vessels

Background: Cardiovascular diseases are the leading cause of death worldwide. These are manifested by, inter alia, the mechanical degradation of the blood vessels. The source of the mechanical strength of blood vessels is primarily influenced by type-I collagen fibers.

Methods: This study introduces a novel bio-composite consisting of ultralong collagen fibers (cm scale), derived from soft corals, and embedded within an alginate matrix. The new bio-composite was used to fabricate a graft towards tissue engineered blood vessels. The mechanical properties of the individual composite layers were investigated and compared with reported native tissue properties. Subsequently, mechanical tests and finite element simulations of layered cylindrically-shaped bio-composite grafts were conducted. Next, cytotoxicity of the bio-material was tested and fibroblast cell growth metrics including cell growth rate and cell orientation within the composite constructs were examined.

Results: The mechanical properties of the bio-composite layers confirmed our ability to match native tissue properties by tailoring the collagen fiber volume fractions. Simulations of the graft predicted close stress-strain behavior to the measured. The cells remained alive for more than 28 days and demonstrated higher growth rates during the first two weeks. The cells were aligned with the collagen fibers for the entire duration of the experiment.

Conclusions: The novelty of this study is manifested in the use of naturally derived long collagen fibers for the development of a new class of tissue-engineered grafts. The proposed novel bio-composite and associated construct show a great potential for future tissue engineered replacements of blood vessels.