Fiber length and concentration: Synergistic effect on mechanical and cellular response in wet-laid poly(lactic acid) fibrous scaffolds.

Abstract

In the area of biomaterials, fibers not only offer increased mechanical response, but also serve as an extracellular matrix mimicking morphology to direct cellular attachment and proliferation. While biologically similar in morphology, soft, and flexible hydrogel materials have low mechanical properties. For applications in tissue engineering, the lack of directional cues and attachment regions within the biogels is undesired as cells require a guide for adequate attachment and organized proliferation. In this work, we have investigated the role of poly(lactic acid) (PLA) fiber length and concentration as a reinforcement phase in a gelatin hydrogel matrix and the resultant mechanical and cellular responses. With increasing fiber length and concentration, the ultimate tensile strength, modulus, and toughness increased for the samples. Similarly, for shorter fiber lengths, the loss and storage modulus increased with fiber concentration. After seeding human mesenchymal stem cells (hMSCs) onto the neat fibrous scaffolds it was found that the fabrication process imparted no cytotoxicity. Furthermore, it was the concentrations and lengths of fiber both caused discernable differences in cell viability at the extreme values. Fibers of all lengths, when in a 4.0 wt % concentration, had a decrease in cell viability after 10 days while the 12.7 mm fibers showed a similar response at 2.0 wt %, but all stayed about 90% viability. With increased incubation time, hMSCs became elongated with increased proliferation. These results indicate that the wet-lay process is a rapid and scalable method by which fibrous 3D-scaffolds can be produced to reinforce hydrogel matrices. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 332-341, 2019.