Combining electrospinning with 3D printing towards hierarchical architectures

Abstract:

The design of biomaterials for tissue engineering and regenerative medicine is a complex task, as it involves mimicking the complexity and hierarchical architectures of natural tissues and organs. While single techniques and materials can be used to fabricate simple structures, the fabrication of complex structures requires a more advanced approach. Promising approach is the combination of electrospinning and 3D printing, which can be used to create hierarchical micro/nano architectures that mimics the natural extracellular matrix (ECM) and geometry of tissues and organs such as vascular grafts. The arterial wall structure is organized into three concentric layers: intima, media and adventitia working in tandem to withstand the physiologically rigorous pressure conditions of the body and maintain homeostasis. Thus, fabricated three-dimensional tubular engineered vascular graft must provide a platform for cell migration, proliferation, and differentiation while mimicking the structural and mechanical integrity of native vascular extracellular matrix (ECM).

In our work, we performed the manufacturing of the micro/nano tubular hierarchical structures using 3D printing and electrospinning with new poly(butylene succinate-dilinoleic succinate)(PBS-DLS) copolymers modified by poly(ethylene glycol)(PEG). These new copolymers show biodegradation in presence of enzymes and very good in vitro biocompatibility in contact with mouse fibroblasts thus indicating their suitability for medical applications. The copolymers were evaluated for their processability to fabricate 5 mm diameter vascular grafts. The crystallized polymers were formulated directly from the reactor into filaments of 1.75mm diameter, suitable for fused filament fabrication 3D printing, thus eliminating the need for post-processing. Further, the 3D printed tubes served as supports to collect nanofibers during the electrospinning. The nanofibrous network indicated the formation of 400nm to 600nm thick fibres. The morphology of fabricated constructs has been verified by scanning electron microscopy (SEM) showing formation of micro- and nanoarchitectures with good interconnectivity between two different layers. This approach shows high potential for the fabrication of vascular grafts and other complex tissue structures, as it enables the design and control of both the macro- and nano-scale architectures of the final tissue model.