Assessment of various crosslinking agents on collagen/chitosan scaffolds for myocardial tissue engineering

Suitable material for scaffolds that support cell attachment, proliferation, vascularization and contraction has always been a challenge in myocardial tissue engineering. Much research effort has been focused on natural polymers including collagen, gelatin, chitosan, fibrin, alginate, etc. Among them, a collagen/chitosan composite scaffold was widely used for myocardial tissue engineering. Due to the non-proliferative and contractile characteristics of cardiomyocytes, the biocompatibility and mechanical properties of the scaffolds are extremely important for supporting intercellular connection and tissue function for myocardial tissue engineering. To the best of our knowledge, the three crosslinking agents (glutaraldehyde (GTA), genipin (GP), tripolyphosphate (TPP)) have not yet been comparatively studied in myocardial tissue engineering. Thus, the aim of this study is to compare and identify the crosslinking effect of GTA, GP and TPP for myocardial tissue engineering. The collagen/chitosan scaffolds prepared with various crosslinking agents were fabricated and evaluated for physical characteristics, biocompatibility and contractile performance. All the groups of scaffolds exhibited high porosity (>65%) and good swelling ratio suitable for myocardial tissue engineering. TPP crosslinked scaffolds showed excellent mechanical properties, with their elastic modulus (81.0 ± 8.1 kPa) in the physiological range of native myocardium (20∼100 kPa). Moreover, GP and TPP crosslinked scaffolds exhibited better biocompatibility than GTA crosslinked scaffolds, as demonstrated by the live/dead staining and proliferation assay. In addition, cardiomyocytes within TPP crosslinked scaffolds showed the highest expression of cardiac-specific marker protein and the best contractile performance. To conclude, of the three crosslinking agents, TPP was recommended as the most suitable crosslinking agent for collagen/chitosan scaffold in myocardial tissue engineering.