There is an unmet need for artificial tissue to address current limitations with donor organs and problems with donor site morbidity. Despite the success with sophisticated tissue engineering endeavours, which employ cells as building blocks, they are limited to dedicated labs suitable for cell culture, with associated high costs and long tissue maturation times before available for clinical use. Direct 3D printing presents rapid, bespoke, acellular solutions for skull and bone repair or replacement, and can potentially address the need for elastic tissue, which is a major constituent of smooth muscle, cartilage, ligaments and connective tissue that support organs. Thermoplastic polyurethanes are one of the most versatile elastomeric polymers. Their segmented block copolymeric nature, comprising of hard and soft segments allows for an almost limitless potential to control physical properties and mechanical behaviour. Here we show direct 3D printing of biocompatible thermoplastic polyurethanes with Fused Deposition Modelling, with a view to presenting cell independent in-situ tissue substitutes. This method can expeditiously and economically produce heterogenous, biomimetic elastic tissue substitutes with controlled porosity to potentially facilitate vascularisation. The flexibility of this application is shown here with tubular constructs as exemplars. We demonstrate how these 3D printed constructs can be post-processed to incorporate bioactive molecules. This efficacious strategy, when combined with the privileges of digital healthcare, can be used to produce bespoke elastic tissue substitutes in-situ, independent of extensive cell culture and may be developed as a point-of-care therapy approach.

Introduction: Mimicking physiological functions of nitric oxide (NO) has applications in regenerative medicine. However, few NO delivery systems have progressed to clinical trials owing to limitations in delivery. Materials and methods: A novel NO delivery system was explored by integrating S-nitro-N-acetylpenicillamine-functionalized long-chain aliphatic hydrocarbons (LCAHs) into a polyurethane-based polymer. Results and discussion: Contact angle analysis determined the novel delivery system to be significantly more hydrophobic than control. Chemilluminscence showed a four-phase NO release profile of the delivery system with more stable and prolong NO release than control. Conclusion: LCAHs can optimize the duration and rate of NO delivery and present a viable option for use in surgical implants and biomedical applications.