Mar 02, 2017

3D printing in a clinical setting

3D printing is certainly popular. Papers published in academic journals and the mainstream media frequently praise its potential, covering the latest feats of ingenuity while hinting at future advances that until recently were considered in the realm of science fiction. This is particularly true in the biomedical sector. Reports have focused almost exclusively on the manufacture of advanced, customized devices - airway splints1, bionic ears2- and the distant, but increasingly feasible, prospect of 3D-printed organs and soft tissues, as detailed by Murphy and Atala3. Although enthusiasm and adventure in these advanced applications is guaranteed, readers should also realize that 3D printing offers opportunities in less complex, cheaper and more accessible implementations.

3D printing represents a form of additive manufacturing where end products are realized through the successive layering of materials according to a digitally programmed design. Despite being technologically feasible since the 1980s, its use on a large scale within a nonspecialized environment has realistically been possible for only 3-4 years. This is primarily possible because the cost of 3D printers is no longer prohibitive and user friendly and intuitive computer-assisted designed (CAD) software is now available. Today, these advances, with practive and a certain degree of knowledge, make such 3D printing technically and economically comparable to standard two-dimensional (2D) printing. The clear difference is the expanded scope of what may be achived by the former.

1

Fig. 1 | Programming localized anisotropy via biomimetic 4D printing. One-step alignment of cellulose fibrils during hydrogel composite ink printing. a, Schematic of the shear-induced alignment of cellulose fibrils during direct ink writing and subsequent effects on anisotropic stiffness E and swelling strain . b–d, Direct imaging of cellulose fibrils (stained blue) in isotropic (cast) (b), unidirectional (printed) (c) and patterned (printed) (d) samples (scale bar, 200 µm).

Increasing availability and accessibility has led to the trial of 3D printing by a small but growing number of clinicians and researchers. Recent publications, receiving little praise. have optimistically described 3D printing’s successful application not only to complex medical procedures but also to the production of tools and equipment that facilitate research and practice in many disciplines. Objects of diverse complexity have been manufactured using an array of substrates, from 96-well plates to basic optics equipment4, intricate chemical reactionware5 through to everything needed to run a physiology laboratory6. Clinically, 3D printing has been used to manufacture a range of products, from comparatively simple objects, such as zirconia dental prostheses7 and surgical instruments8, to complex ones, such as models of anatomy and pathology reconstructed from cross-sectional imaging to facilitate medical education and both clinical planning and communication9. As a plus, the designs for these items are often made available online, free, by their creator, and made using common open-source software accessible by all (e.g., www.thingiverse.com). Hence, by connecting a 3D printer, communally shared designs generated by freely available computer programs have, for the first time, allowed the production of open-source scientific and clinical hardware10.

Such an assemble offers several key advantages over both traditional commercial purchasing and internal design and manufacture, the most obvious being cost and time savings10. Researchers and clinicians can label commonly employed items where 3D printing may poutlay is roduce viable end products, download designs and within a few hours have the object ready to use. Printed objects may be used as well in conjunction with or to modify off-the-shelf products, for example, custom-designed centrifuge tubes and plate holders. Once the initial discounted, this approach has been demonstrated to achieve significant cost reduction over commercially available laboratory and medical equipment, which can exceed 99%4,8. In addition, aside from computing literacy and initial set-up, no specialist skills are are required in the design and manufacture of objects, unless post-production physical or chemical customization is required. Thus, access to this technology is not restricted by technical ability, but only by a lack of awareness and/or a willingness to embrace such novel technology.

2

Fig. 2 | FRESH printing of biological structures based on 3D imaging data and functional analysis of the printed parts. (A) A model of a human femur from 3D CT imaging data is scaled down and processed into machine code for FRESH printing. (B) The femur is FRESH printed in alginate, and after removal from the support bath, it closely resembles the model and is easily handled. (C) Uniaxial tensile testing of the printed femur demonstrates the ability to be strained up to 40% and elastically recover. (D) A model of a section of a human right coronary arterial tree from 3D MRI is processed at full scale into machine code for FRESH printing. (E) An example of the arterial tree printed in alginate (black) and embedded in the gelatin slurry support bath. (F) A section of the arterial trees printed in fluorescent alginate (green) and imaged in 3D to show the hollow lumen and multiple bifurcations. (G) A zoomed-in view of the arterial tree shows the defined vessel wall that is <1mmthick and the well-formed lumen. (H) A dark-field image of the arterial tree mounted in a perfusion fixture to position a syringe in the root of the tree. (I) A time-lapse image of black dye perfused through the arterial tree false-colored at time points of 0 to 6 s to show flow through the lumen and not through the vessel wall. Scale bars, 4 mm (B), 10 mm (E), 2.5 mm (F), 1 mm (G), and 2.5 mm (H and I).

We view the arrival of accessible 3D printing as a pivotal moment in translational research for the masses. Not only can scientists, clinicians, engineers, architects and designers alike achieve in-house production of ordinary items with associated cost- and time-saving benefits, but they can also customize existing products or develop entirely new bespoke ones. The free sharing of designs in a collective, decentralized manner clearly supports collaboration. Individuals separated temporally and spatially may contribute with specialist knowledge to the same design, testing the end product for efficiency and suggesting adaptations. In addition, newly developed tools may be rapidly published, accelerating research by other groups while ensuring standardization and reproducibility of results. Individualization of products is also facilitated where modifications to an established design are more readily achieved at a pace and cost unachievable by standard manufacturing approaches. Finally, 3D printing may have special applicability in remote or resource-limited environments - often where healthcare and biomedical research are most needed8,11. Here, the possibility to manufacture laboratory tools and/or clinical equipment from freely available designs using materials with low overheads will be of extreme importance, and could offer a more viable long-term strategy than the traditional supply of expensive, commercially available end-products.

3D printing has the potential to become as invaluable and common an asset in the medical research laboratory or hospital as the centrifuge or microplate reader. The only factor limiting 3D printing’s extensive implementation is a lack of awareness of its accessibility and applications. As bioengineers and clinicians have integrated 3D printing into their research process, it has already delivered in transforming their timelines and cost structure. We would highly recommend this technology to all those interested in accelerating end user-inspired biomedical innovation - get one, you won’t regret it. 

References:

  1. Zopf, D.A. et al. N. Engl. J. Med. 368, 2043–2045 (2013).
  2. Mannoor,  M.S.  et  al.  Nano  Lett.  13,  2634–2639 (2013). 
  3. Murphy, S.V . & Atala, A. Nat. Biotechnol. 32, 773–785 (2014).
  4. Zhang, C. et al. PLoS ONE 8, e59840 (2013). 
  5. Symes, M.D. et al. Nat. Chem. 4, 349–354 (2012).
  6. Sulkin, M.S. et al. Am. J. Physiol. Heart Circ. Physiol. 305, H1569–H1573 (2013). 
  7. Ebert, J. et al. J. Dent. Res. 88, 673–676 (2009). 
  8. Rankin,  T.M.  et  al.  J.  Surg.  Res.  189,  193–197 (2014).
  9. Zein, N.N. et al. Liver Transpl. 19, 1304–1310 (2013).
  10. Pearce, J.M. Science 337, 1303–1304 (2012). 
  11. Lang, T. Science 331, 714–717 (2011). 
 
Tagged under