3D bioprinting for meniscus tissue engineering: a review of key components, recent developments and future opportunities

3D bioprinting has the potential to transform the field of regenerative medicine as it enables the precise spatial patterning of biomaterials, cells and biomolecules to produce engineered tissues. Although numerous tissue engineering strategies have been developed for meniscal repair, the field has yet to realize an implant capable of completely regenerating the tissue. This paper first summarized existing meniscal repair strategies, highlighting the importance of engineering biomimetic implants for successful meniscal regeneration. Next, we reviewed how developments in 3D (bio)printing are accelerating the engineering of functional meniscal tissues and the development of implants targeting damaged or diseased menisci. Some of the opportunities and challenges associated with use of 3D bioprinting for meniscal tissue engineering are identified. Finally, we discussed key emerging research areas with the capacity to enhance the bioprinting of meniscal grafts.

Biomimetic design considerations for 3D-printed joints

3D-printing innovations are being explored as a uniting framework for the future of individualized joint replacement. The ability to convert 2D medical images to adjustable 3D models means a patient’s own anatomy can serve as the foundation for implant design. There are three biomimetic design considerations to understand the research on these new implants. First, optimizing the unit cell of 3D models can give researchers the essential building block necessary to 3D-print reliable artificial joints. Second, adequate porosity when designing a 3D-printed biomimetic joint is a balance between strength and the need for osseointegration. Third, functionally graded material as a design principle connects unit cell and porosity to create a 3D-printed product with complex properties along different spacial axes. 3D printing offers the opportunity to incorporate biomimetic design principles that were previously unobtainable with traditional manufacturing methods.

Deep learning in bioengineering and biofabrication: a powerful technology boosting translation from research to clinics

Bioengineering has been revolutionizing the production of biofunctional tissues for tackling unmet clinical needs. Bioengineers have been focusing their research in biofabrication, especially 3D bioprinting, providing cutting-edge approaches and biomimetic solutions with more reliability and cost–effectiveness. However, these emerging technologies are still far from the clinical setting and deep learning, as a subset of artificial intelligence, can be widely explored to close this gap. Thus, deep-learning technology is capable to autonomously deal with massive datasets and produce valuable outputs. The application of deep learning in bioengineering and how the synergy of this technology with biofabrication can help (more efficiently) bring 3D bioprinting to clinics, are overviewed herein.

MeTiS: a modular pipeline for extracting 3D-printable brain-surface models from conventional and ultra-high field MRI

Aim: To develop a modular software pipeline for robustly extracting 3D brain-surface models from MRIs for visualization or printing. No other end-to-end pipeline specialized for neuroimaging does this directly with an interchangeable combination of methods. Materials & methods: A software application was developed to dynamically generate Nipype workflows using interfaces from the Analysis of Functional NeuroImages, Advanced Normalization Tools, FreeSurfer, BrainSuite, Nighres and the FMRIB Software Library suites. The application was deployed for public use via the LONI pipeline environment. Results: In a small, head-to-head comparison test, a pipeline using FreeSurfer for both the skull stripping and cortical-mesh extraction stages earned the highest subjective quality scores. Conclusion: We have deployed a publicly available and modular software tool for extracting 3D models from brain MRIs to use in medical education.

3D printing in spine surgery: current and future applications

The revolutionary technology of 3D printing has gained traction in the medical field in recent years; spine surgery has in particular seen major advances in 3D printing. The applications of this technology have grown from utilizing 3D models to enhance patient education to patient specific, highly detailed intraoperative anatomical molds. However, obstacles remain that prevent the widespread utilization of 3D printing in spine surgery such as cost, time consumption, lack of long-term data, and regulation by the US FDA. Despite these obstacles, it is evident that 3D printing will be utilized to optimize preoperative, intraoperative, and postoperative care of patients with spine deformity. The purpose of this review is to establish the applications of 3D printing for spine surgery.

Bespoke regulation for bespoke medicine? A comparative analysis of bioprinting regulation in Europe, the USA and Australia

Like most health-technology innovators, bioprinters are required to traverse a complex landscape featuring varied forms of regulation. This article focuses on one of the most complex aspects: the requirement imposed by regulatory authorities to satisfy them of the safety, efficacy and clinical utility of resultant healthcare products. Satisfaction of such requirements can result in a significant lag between ‘breakthrough’ and clinical delivery. This article examines this aspect of regulation in the USA, Europe and Australia, three leading bioprinting research jurisdictions. In particular, it examines medical devices and medicines categories of regulation, questioning whether a new approach to regulation is required or whether existing product-based regimes are sufficiently adaptive.

Evaluation of 3D-printer settings for producing personal protective equipment

Aim: COVID-19 resulted in a shortage of personal protective equipment. Community members united to 3D-print face shield headbands to support local healthcare workers. This study examined factors altering print time and strength. Materials & methods: Combinations of infill density (50%, 100%), shell thickness (0.8, 1.2 mm), line width (0.2 mm, 0.4 mm), and layer height (0.1 mm, 0.2 mm) were evaluated through tensile testing, finite element analysis, and printing time. Results: Strength increased with increased infill (p < 0.001) and shell thickness (p < 0.001). Layer height had no effect on strength. Increasing line width increased strength (p < 0.001). Discussion: Increasing layer height and line width decreased print time by 50 and 39%, respectively. Increased shell thickness did not alter print time. These changes are recommended for printing.