Improved mechanical properties by modifying fibrin scaffold with PCL and its biocompatibility evaluation

Previous studies have proved that fibrin is an excellent scaffold material for tissue engineered blood vessel. However, the mechanical properties of fibrin are not enough. One way to solve the problem is to combine polymer materials with fibrin to enhance its biomechanical properties. In this study, a novel polycaprolactone (PCL)/fibrin composite scaffold was prepared by electrospinning technology. The morphological, physicochemical analysis, blood compatibility, biomechanical properties, biocompatibility and biodegradability of this vascular scaffold were evaluated. The results showed that electrospun PCL/fibrin scaffold possessed smaller aperture and larger fiber diameter than that of fibrin scaffold. The swelling ratio of the vascular PCL/fibrin scaffold at (0:100), (10:90), (20:80) and (30:70) was 112 +/- 5.3, 103 +/- 6.9, 94 +/- 5.9 and 89 +/- 3.4%, respectively. Mechanical properties of fibrin scaffolds were enhanced significantly by the addition of PCL. Furthermore, the time of plasma re-calcification, activated partial thromboplastin time and thromboplastin time in four different proportions of PCL/fibrin scaffolds were similar to that of the control group. Degradation experiments in vitro demonstrated that the degradation rate of PCL/fibrin scaffold was closely related to the content of PCL. MTT assays and immunofluorescence staining indicated that the stem cells cocultured with the PCL/fibrin scaffold had good proliferation behavior. Live/dead assay confirmed that the number of MSCs in the PCL/fibrin (10:90) group was significantly increased as compared to other groups. The tests in vivo results showed PCL/fibrin scaffold could promote cell infiltration and tissue regeneration and its degradation in vivo was faster than that of PCL scaffold. In summary, PCL/fibrin (20:80) scaffold exhibited balanced mechanical properties and degradability, as well as good cell compatibility properties; therefore, it was a promising tissue engineering material for vascular graft.