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The commercial 3D bioprinting industry
The commercial 3D bioprinting industry
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E. Combellack*,†, Z.M. Jessop*,†, I.S. Whitaker*,† Reconstructive Surgery and Regenerative Medicine Research Group, Swansea University Medical School, Swansea, United Kingdom, †The Welsh Centre for Burns and Plastic Surgery, Morrison Hospital, Swansea, United Kingdom
*
20.1 Introduction Modern three-dimensional (3D) bioprinting promises the creation of bespoke tissue-engineered constructs that would herald the end of donor site morbidity, creation of solid complex organs “made to order,” and facilitate a revolution in both biological sciences and medical research. Biotechnology companies along with major laboratories worldwide, in response to this potential, have invested decades and millions of dollars in the development of printing technology and its applications across a number of disciplines. The relatively simple core principle of stereolithography developed in the 1980s has sparked a materials and technological revolution that has seen the development of more precise printers, intelligent bioinks, and scaffold materials capable of supporting de novo tissue growth. The original aims of producing solid 3D polymer models have been superseded, and today 3D bioprinting is used in a range of scientific and commercial fields such as in drug delivery systems, cosmetic testing, and in the printing of customized 3D scaffolds to support tissue growth [1–3]. While much of the activity worldwide is research based, there is already a significant commercial element, which incorporates these new technologies into modern practice. The current uses of 3D printing include the creation of devices and implants which have been available for a number of years and allow the production of personalized implants to augment operative technique and bespoke 3D prosthesis for reconstruction [4–6]. The added biological component to 3D printing moves this relatively established technology into a different sphere of potential manufacturing and revenue streams. There are a number of key areas within which bioprinting may convey a paradigm shift and alter the way in which companies, health-care providers, and consumers interact. Broadly speaking, some of these key areas involve tissue engineering of solid organ transplants, cosmetic and consumer testing, and drug discovery. Along with food and animal products, biosensors and implants, bioprinting has the potential to transform the way in which personalized manufacturing might shape and impact our lives over the next 30 years. In this chapter, we give a brief overview of the current global market, key areas of significant investment and growth, and discuss some of the companies leading the way in 3D bioprinting. The bioprinting landscape and key translational steps needed to deliver this technology to market will be discussed 3D Bioprinting for Reconstructive Surgery. https://doi.org/10.1016/B978-0-08-101103-4.00029-6 © 2018 Elsevier Ltd. All rights reserved.
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further and touching on future challenges, we discuss how these barriers might be overcome to ensure that the full potential of this novel technology is delivered.
20.2 The market Each of the bioprinting companies on the market, whether developing their own platform technology or adapting the existing hardware, uses one of the four main print-head technologies: extrusion, laser-induced forward transfer (LIFT), inkjet, and microvalve [7–14]. Between 2014 and 2015, the 3D bioprinting market saw the entry of a number of new companies, start-ups, spinouts, and subsidiaries all vying for a place in this developing field. Investment and initial valuations have been driven by future promises and early demonstration of potential application of their bioprinting technology [15,16]. As such it is difficult to estimate the value of these companies who all promise target delivery of printed tissue first with astronomical revenue potential.
20.2.1 3D printing: The evolution of the base technology To put 3D bioprinting into context, it is important to understand the development of the 3D printing and additive manufacturing (AM) industry over the last 30 years. In 2013, it was estimated that this market was worth around $1.3 billion with forecasts that would rise to between $4 and 6 billion by 2018 [16,17]. A number of major companies have announced a significant investment into 3D printing and AM in the last 2 years. Stryker announced in January 2016 that it would spend nearly $400 million building an AM facility for the production of implants, with Siemens in Sweden, and UK-based Metalysis investing €21.4 and £20 million, respectively, in printing technology and infrastructure [16]. Comparably 3D bioprinting is still in its infancy; however, market and tech forecast of leading companies suggest that ultimately the market will be measured in the tens of billions of dollars with an initial value of around $1.8 billion achieved by 2027 [15]. With the introduction of a new technology there is variable uptake and a need for significant and sustained investment in addition to a fundamental consumer need or perceived gap, which must exist for a product to be fully integrated into the marketplace. Each year Gartner produces its technology maturation curve or the “hype cycle” for new and emerging technologies as a way of informing the market and separating fleeting technologies from those, which are commercially viable with transformational potential. Cycling through the initial interest and influx of investment during the primary phase of innovation trigger, technologies must weather the peak of inflated expectation through the trough of disillusionment before emerging into the plateau of productivity. 3D bioprinting has relied on the success of 3D printing to garner interest and investment. Hype for the base technology, which was developed in the 1980s really began in 2014 when the first industrial-grade 3D printers entered the marketplace and demonstrated that it was possible to print in high-definition resin or metal [18]. The consumer market responded with smaller “desktop” printers shortly after, which
The commercial 3D bioprinting industry415 Advanced analytics with self-service delivery Autonomous vehicles Internet of things Speech-to-speech translation Machine learning Wearables Cryptocurrencies Consumer 3D printing Natural-language question answering
Expectations Smart advisors Microdata centers Digital dexterity Software-defined security Neurobusiness Citizen data science Biochips loT platform Connected home Affective computing Smart robots 3D bioprinting systems for organ transplant Volumetric displays Human augmentation Brain-computer interface Quantum computing
Hybrid cloud computing
Enterprise 3D printing
Augmented reality
Gesture control Bioacoustic sensing People-literate technology Digital security
Virtual reality Autonomous field vehicles
Cryptocurrency exchange Virtual personal assistants Smart dust
Innovation trigger
Peak of inflated expectations
As of July 2015 Trough of disillusionment
Slope of enlightenment
Plateau of productivity
Time Plateau will be reached in: <2 years
2–5 years
5–10 years
more than 10 years
Obsolete before plateau
Fig. 20.1 2015 Hype cycle for emerging technologies demonstrating the position of 3D printing having peaked the previous year, now heading toward the trough of disillusionment [19].
was made possible by the expiration of a number of key patents detailing the original 3D printing process. The consumer demand for the technology increased exponentially as did the applications in medical device and implants resulting in a spike in unit production [18]. The lack of surrounding infrastructure however, complexity of programming, and poor user interface meant that the consumers were left disillusioned and the initial investment wavered meaning that only a year later it was on the downward slope [19] (Fig. 20.1). In the 24 months that followed, however, a number of companies including P&G, HP, and GE have all invested heavily in 3D printing and bioprinting as expectations have been reset and the application of this technology has focused on the industrial and commercial applications within the marketplace. 3D printing is expanding commercially with scale no longer being a barrier, most recently demonstrated by the San Francisco-based start-up Apis Cor, who printed an entire house in 24 h [20]. Similarly, bioprinting has now become a key investment priority for Big Pharma, medical devices, and cosmetic companies, which has seen the technology diverge from traditional printing, and coupled with biological advancements in cell source and scaffold material creates opportunities to meet potentially significant gaps in the market.
20.2.2 Bioprinting: The gap in the market Initially focusing on the commercial and industrial market it becomes possible to identify strategic gaps, which create a potential opportunity for bioprinting companies. The cost of drug development is becoming prohibitively expensive and stricter guidance around animal testing means that the pharmaceutical and cosmetic
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c ompanies are looking for more cost-effective alternatives without compromising results. Procter and Gamble (P&G) has already banned animal testing on all but the 20% of its products which require it by law [21] mandating an alternative approach to product testing. In health care, waiting lists for patients on long-term dialysis or approaching end-stage liver failure present an economic health burden felt by every health system in the world. Tissue engineering promises the creation of solid organ transplants that would save thousands each year and lift the chronic health burden. In addition, tissue engineering holds the potential to restore form and function to patients born with congenital deformity or who acquire it later in life secondary to trauma or malignancy. Bioprinting companies have recognized the opportunity to supply the health-care sector with personalized tissue-engineered constructs and the investment is reflected in the development of advanced printer systems and the creation of novel biomaterials [1,22–24].
20.2.2.1 Tissue engineering Tissue engineering is a promising technology but not as mature as the cellular therapy sector. Replacement of damaged or missing tissue in pursuit of restoration of form and function is the holy grail of tissue engineering. An interdisciplinary field, it relies on an optimized cell source, scaffold, and printing technology to create de novo tissue fit-for-purpose. A decade on from the Vacanti mouse, we saw the first report of a tissue-engineered organ (bladder) being implanted into a patient [25]. Since then, the technology has advanced significantly and several organs and tissues have been engineered and implanted into patients; however, the materials engineering and cell biology require further work [26]. Flat structures such as the skin, which are the most efficient to engineer, have seen the most progress and examples of technology being offered to patients for wound healing include Integra (collagen scaffolds) as well as cellular matrices such as Apligraft. Bioprinting is a platform technology that has the potential to expand the tissue engineering field by allowing production of more complex tissues for reconstructive surgery using the bottom-up approach rather than decellularizing the existing structures. Bioprinting firms have diversified to include a range of cell source, scaffold material, and printing techniques in order to address some of the key hurdles and translational steps, but the same fundamental scientific questions exist to allow production of native-like tissues.
20.2.2.2 Organ transplant With the development of intelligent bioinks, novel scaffold materials, and diverse cell sources, 3D bioprinting has the potential to answer a number of clinical and research-based questions. Significant commercial potential lies within the field of tissue engineering and the creation of bioprinted 3D solid organs. The need for organ donation globally presents a set of unique challenges that mean an ever-increasing population of patients are waiting for a donor match. In 2014 more than 119,000 transplants were performed worldwide, an increase of almost 2% from the year previously and desperately short of total global need accounting for <10% of all transplant patients
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waiting [27]. The current system is a resource-intensive service, which has been under increasing scrutiny in the environment of austerity and economic constraints [28]. The promise to eliminate the waiting time, need for immunosuppression, and a donor-matched organ has attracted significant financial, research, and technological investment with the potential to change lives significantly [29–32]. In current tech reports which are forecasting into the late 2020s, it is theorized that this technology may be achievable within our lifetimes. However, it is more likely that simple structural tissues such as the cartilage and bone used in reconstructive surgeries will be some of the first transplanted due to the inherent complexity in architecture and function of solid organs which is more difficult to reproduce. A 30-year horizon view estimates that it is conceivable that the health-care burden created by organ transplant will be substantially reduced with issues revolving around a route to market, up-scaling production to meet complex global demand, and regulation of manufacturing and implantation quality control [15,33].
20.2.2.3 Drug development Drug discovery is a highly expensive and resource-heavy process that often results in failure to reach market and clear final regulatory hurdles due to lack of sufficient preclinical data, which accurately demonstrates the testing methodologies [33]. With the estimated cost of a new drug to market at around $2.6 billion, reliance on animal testing and 2D human cell assays is often a poor substitute for the human model and results in a significant cost to the pharmaceutical company [34]. In 2014, the bioprinting company Organovo's first product to market was a 3D-bioprinted liver assay which survived for 40 days and allowed more accurate toxicity testing and metabolic studies of pharmaceuticals [35]. With more companies now offering 3D-bioprinted tissue models including liver, kidney, lung, and thyroid, drug companies are better positioned to complete early phase testing before applying to proceed into first-phase human trials.
20.2.2.4 Cosmetic testing In 2013, the European Union issued a ban covering both the testing of cosmetic products and ingredients on animals, and bringing to market any product which had been tested on animals [36]. While the ban on cosmetic component testing had been in effect since 2009, the ban on testing finished cosmetics came into effect the following year in September 2014. This raised a number of issues with cosmetic companies manufacturing and selling their products within the EU. To address this, companies such as L'Oreal have turned to 3D bioprinting as part of the solution. In 2013, in advance of the ban enforcement, it had set up a partnership with Organovo to create skin models for cosmetic testing [21,33]. Organovo was able to print live cells at a cellular concentration of 100% creating the skin models required to gain essential information during the process of product development. Proctor & Gamble has also set up a $44 million fund as part of a wider 5-year research plan to invite researchers (primarily in Singapore) to submit proposals and bring bioprinting expertise into P&G. As the 3D models printed become more robust, the scope of testing will increase, significantly reducing the need for external testing, while meeting the legal and ethical obligations required [2,37,38].
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20.3 Key companies With a market expected to be worth around $1.8 billion by 2027, it is understandable that each year more companies are entering the market and established 3D printing companies are expanding to offer bioprinters and hardware to support this emerging field. Broadly speaking, companies are diverging into one of the two categories: focusing on the printers and support for the physical machinery with and without bioink supply, and those focusing on the production of 3D-bioprinted products such as skin models, assays, and tissue for cosmetic and drug testing. Companies with more than a decade of 3D printing experience such as EnvisionTEC have diversified and are now manufacturing bioprinters for biofabrication and implants which cost just under $200,000 which have been available since the early 2000s. They have an established supply chain and are simply adapting existing technology to “keep up” with the changing landscape while maintaining their core business,continuing to supply 3D printers to a number of commercial and industrial sectors. Start-ups focusing solely on 3D bioprinting such as BioBots which was founded by two friends at the University of Pennsylvania in 2013 have already developed two versions of their desktop 3D bioprinter, the latest of which costs around $5000. In 2015, they raised $1.5 million in funding and with more than 100 units of their BioBot 1 printer sold, they have made an estimated $1 million in revenue to date [39]. The concept is clear; they are offering an accessible entry-level product, which allows smaller research institutions to buy the technology into their organizations without any significant research investment. By providing on-going tech-support BioBots are able to access a wealth of free user data as it refines its technology ready for the next model to be released. In addition, they produce a range of support and sacrificial biopinks to use specifically in their machines; conceivably, you only need to add the cellular component and you are ready to go. There are a number of spin offs such as OxSyBio from Oxford University whose aim is to develop 3D printing techniques to produce a functional range of tissues for the repair and replacement of organs and skin. Although they raised £1 million in 2015 from the IP Group PLC to develop their proprietary droplet printing technology they are still in the research phase and as of yet do not have a product to take to market. Another company, CELLINK, initially focused on developing bioinks for extrusion bioprinting, is now expanding into producing bioprinters aimed at life science companies and researchers. Despite the substantial investment to date, many of the more strategically placed companies are yet to post significant profits, rather generating revenues from research grants and kick-starter or open platform fundraising. Organovo, the only publically traded bioprinting company, generated huge interest when it first went public and at one point trading at an estimated value of $1 billion despite having generated minimal profit. There is a fine balance however, and after their CEO and cofounder Keith Murphy left in April 2017 their share price bore the brunt, falling nearly 8% in the hours following the announcement. Their new CEO Taylor Crouch has previous experience with eStudySite, which in part conducted clinical trials, will be essential as Organovo aims to bring more of its bioprinted products to market and boost its revenue streams. It is important however to bear in mind that without extensive track records or significant profits, all bioprinting companies, public
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or privately owned, rely on the hype and promise of what is to come. The key will be sustaining the interest and investment while the technology catches up with the imagination and aspirations of the commercial markets.
20.4 Translational steps The refinement of current technologies will be an essential part of the progression not only of the technology but also of the logistical process, which will support the product to market. Regardless of the estimated value of these innovative tech start-ups, all they need is a sustainable way of generating revenue in the medium to long term by reliably bringing a product to market. No product can get to market without a robust end-to-end supply chain and as the technology develops, so too the regulation and infrastructure that surrounds this new technology. Regulatory boards that monitor and manage implantable devices will be quick to halt any process, which does not meet the standards designed to protect patient safety and guarantee traceability. Large-scale production to meet regional, national, or international demand must also be considered, with raw materials, processes, and storage not generating a total item cost that would put it beyond the reach of most health-care systems.
20.5 Future development Incremental advancements in 3D printing technology are getting ever smaller as the techniques are refined and the market place becomes more crowded. At some point producing a smaller printer will no longer be enough to gain market share and reliability along with a range of scaffolds and more diverse cell sources will become the economic differentiators. Market analysts are already talking about the next evolution within bioprinting, hinting that the addition of an extra dimension will alter the way in which bioprinting is ultimately utilized [40]. 4D printing hints at advanced technology that allows printed constructs or implants to respond to their environment promising wearable or implantable technology that adapts to the underling host system, external signal, or disease process [41–44]. The 3D bioprinting field offers unprecedented opportunity to change the paradigm in health care, but requires significant investment as well as the conviction to push the research through to clinical translation.
References [1] Chia HN, Wu BM. Recent advances in 3D printing of biomaterials. J Biol Eng 2015;9(1):1728. [2] Vijayavenkataraman S, Lu WF, Fuh JYH. 3D bioprinting of skin: a state-of-the-art review on modelling, materials, and processes. Biofabrication 2016;8(3):032001. [3] Hsieh FY, Lin HH, Hsu S. 3D bioprinting of neural stem cell-laden thermoresponsive biodegradable polyurethane hydrogel and potential in central nervous system repair. Biomaterials 2015;71:48–57.
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[4] Ventola CL. Medical applications for 3D printing: current and projected uses. P T 2014;39:704–11. [5] Prakash BB. 3D printing and its applications. Int J Sci Res 2016;5(3):1532–5. [6] Nale SB, Kalbande AG. A review on 3D printing technology. Int J Innov Emerg Res Eng 2015;2(9):33–6. [7] Gudapati H, Dey M, Ozbolat I. A comprehensive review on droplet-based bioprinting: past, present and future. Biomaterials 2016;102:20–42. [8] Ng WL, Yeong WY, Naing MW. Microvalve bioprinting of cellular droplets with high resolution and consistency. Proceedings of the 2nd international conference on progress in additive manufacturing (Pro-AM 2016); 2016. p. 397–402. [9] Catros S, Fricain JC, Guillotin B, Pippenger B. Laser-assisted bioprinting for creating on-demand patterns of human osteoprogenitor cells and nano-hydroxyapatite. Biofabrication 2011;3:025001. IOPscience. [10] Xu T, Jin J, Gregory C, Hickman JJ, Boland T. Inkjet printing of viable mammalian cells. Biomaterials 2005;26(1):93–9. [11] Arai K, Iwanaga S, Toda H, Genci C, Nishiyama Y, Nakamura M. Three-dimensional inkjet biofabrication based on designed images. Biofabrication 2011;3(3):034113. [12] Roth EA, Xu T, Das M, Gregory C, Hickman JJ, Boland T. Inkjet printing for high- throughput cell patterning. Biomaterials 2004;25(17):3707–15. [13] Michael S, Sorg H, Peck C-T, Koch L, Deiwick A, Chichkov B, et al. Tissue engineered skin substitutes created by laser-assisted bioprinting form skin-like structures in the dorsal skin fold chamber in mice. PLoS One 2013;8(3):e57741. [14] Lee JM, Yeong WY. Design and printing strategies in 3D bioprinting of cell-hydrogels: a review. Adv Healthc Mater 2016;5(22):2856–65. [15] Tsao N. 3D Bioprinting 2017-2027: technologies, markets, forecasts. www.idtechex. com; 2017. Available from: http://www.idtechex.com/research/reports/3d-bioprinting2017-2027-technologies-markets-forecasts-000537.asp [cited 16 September 2016]. [16] Associates W. Additive manufacturing: the state of the industry. Wohlers Report; 2016 Aprïl p. 1–6. [17] Gonzalez EE, la Cerda de R. Quo Vadis; 2015. p. 6. Available from: https://www.pwc. com/mx/es/industrias/archivo/2015-04-quovadis.pdf [cited 24 July 2017]. [18] Hilkene C. 3D printing in 2017: moving past disillusionment and into production applications. www.idtechex.com; 2017. Available from: https://www.ame.org/target/articles/ 2017/3d-printing-2017-moving-past-disillusionment-and-production-applications [cited 25 July 2017]. [19] Gartner. Gartner's 2015 Hype cycle for emerging technologies identifies the computing innovations that organizations should monitor; 2015. Available from: http://www.gartner. com/newsroom/id/3114217 [cited 27 July 2017]. [20] Apis Cor. The first on-site house has been printed in Russia. www.apis-cor.com; 2017. Available from: http://apis-cor.com/en/about/news/first-house [cited 21 July 2017]. [21] Gordon R. P&G, L'Oreal push 3D bioprinting from research to commercial products. www.idtechex.com. Available from: http://www.idtechex.com/research/articles/p-g- loreal-push-3d-bioprinting-from-research-to-commercial-products-00007888.asp?donotredirect=true [cited 27 July 2017]. [22] Chen F-M, Liu X. Advancing biomaterials of human origin for tissue engineering. Prog Polym Sci 2016;53:86–168. [23] Zhang YS, Arneri A, Bersini S, Shin SR, Zhu K, Goli-Malekabadi Z, et al. Bioprinting 3D microfibrous scaffolds for engineering endothelialized myocardium and heart-on-achip. Biomaterials 2016;110:45–59.
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[24] Lee J-S, Hong JM, Jung JW, Shim J-H, Oh J-H, Cho D-W. 3D printing of composite tissue with complex shape applied to ear regeneration. Biofabrication 2014;6(2):024103. [25] Atala A, Bauer SB, Soker S, Yoo JJ, Retik AB. Tissue-engineered autologous bladders for patients needing cystoplasty. Lancet 2006;367(9518):1241–6. [26] Vacanti CA, Cima LG, Ratkowski D, Upton J, Vacanti JP. Tissue engineered growth of new cartilage in the shape of a human ear using synthetic polymers seeded with chondrocytes. MRS Proc 2011;252:475. [27] Reports 2014—GODT. 2016. Available from: http://www.transplant-observatory.org/ data-reports-2014/. [28] Axelrod DA. Economic and financial outcomes in transplantation. Curr Opin Organ Transplant 2013;18(2):222–8. [29] Mironov V, Boland T, Trusk T, Forgacs G. Organ printing: computer-aided jet-based 3D tissue engineering. Trends Biotechnol 2003;21(4):157–61. [30] Marx V. Tissue engineering: organs from the lab. Nature 2015;522(7556):373–7. [31] Marga F, Jakab K, Khatiwala C, Shepherd B, Dorfman S, Hubbard B, et al. Toward engineering functional organ modules by additive manufacturing. Biofabrication 2012;4(2):022001. [32] Murphy SV, Atala A. 3D bioprinting of tissues and organs. Nat Biotechnol 2014;32(8):773– 85. Nature Publishing Group. [33] IDTechX. 3D Bioprinting 2014-2024: Applications, Markets, Players. www.idtechex. com; 2015. p. 1–104. Available from: http://www.idtechex.com/research/articles/3d-bioprinting-2014-2024-applications-and-markets-00006479.asp?donotredirect=true [cited 26 July 2017]. [34] Mullard A. New drugs cost US$2.6 billion to develop. Nat Rev Drug Discov 2014;13(12):877. [35] Murphy K. Organovo’s bioprinting platform: enabling 3D, architecturally correct, fully human tissue for drug discovery and transplantation. Organovo. Available from: http:// organovo.com/cell-gene-meeting-mesa/ [cited 27 July 2017]. [36] European Commision. Ban on animal testing. European Commision; 2013. Available from: https://ec.europa.eu/growth/sectors/cosmetics/animal-testing_en [cited 20 July 2017]. [37] Velasquillo C, Galue EA, Rodriquez L, Ibarra C. Skin 3D bioprinting. J Cosmet Dermatol Sci Appl 2013;3:85–9. [38] Cubo N, Garcia M, del Cañizo JF, Velasco D, Jorcano JL. 3D bioprinting of functional human skin: production and in vivo analysis. Biofabrication 2016;9(1):1–12. IOP Publishing. [39] Dill K. Inside the company that wants to put a $10,000 3D bioprinter on every lab bench. Forbes; 2016. Available from: https://www.forbes.com/sites/kathryndill/2016/11/02/inside-the-company-that-wants-to-put-a-10000-3d-bioprinter-on-everylab-bench/#3e961f4edf30 [cited 21 July 2017]. [40] Panetta K. 3 Trends appear in the gartner hype cycle for emerging technologies; 2016. Available from: http://www.gartner.com/smarterwithgartner/3-trends-appear-in-the- gartner-hype-cycle-for-emerging-technologies-2016/ [cited 22 July 2017]. [41] Li Y-C, Zhang YS, Akpek A, Shin SR, Khademhosseini A. 4D bioprinting: the next-generation technology for biofabrication enabled by stimuli-responsive materials. Biofabrication 2016;9(1):012001. [42] Gao B, Yang Q, Zhao X, Jin G, Ma Y, Xu F. 4D bioprinting for biomedical applications. Trends Biotechnol 2016;34(9):746–56. [43] An J, Chua CK, Mironov V. A perspective on 4D bioprinting. Int J Bioprint 2016;2:3–5. [44] Leist SK, Zhou J. Current status of 4D printing technology and the potential of light- reactive smart materials as 4D printable materials. Virtual Phys Prototyp 2016;11(4):249– 62. 1st ed., Taylor & Francis.
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E. Combellack*,†, Z.M. Jessop*,†, I.S. Whitaker*,† Reconstructive Surgery and Regenerative Medicine Research Group, Swansea University Medical School, Swansea, United Kingdom, †The Welsh Centre for Burns and Plastic Surgery, Morrison Hospital, Swansea, United Kingdom
*
20.1 Introduction Modern three-dimensional (3D) bioprinting promises the creation of bespoke tissue-engineered constructs that would herald the end of donor site morbidity, creation of solid complex organs “made to order,” and facilitate a revolution in both biological sciences and medical research. Biotechnology companies along with major laboratories worldwide, in response to this potential, have invested decades and millions of dollars in the development of printing technology and its applications across a number of disciplines. The relatively simple core principle of stereolithography developed in the 1980s has sparked a materials and technological revolution that has seen the development of more precise printers, intelligent bioinks, and scaffold materials capable of supporting de novo tissue growth. The original aims of producing solid 3D polymer models have been superseded, and today 3D bioprinting is used in a range of scientific and commercial fields such as in drug delivery systems, cosmetic testing, and in the printing of customized 3D scaffolds to support tissue growth [1–3]. While much of the activity worldwide is research based, there is already a significant commercial element, which incorporates these new technologies into modern practice. The current uses of 3D printing include the creation of devices and implants which have been available for a number of years and allow the production of personalized implants to augment operative technique and bespoke 3D prosthesis for reconstruction [4–6]. The added biological component to 3D printing moves this relatively established technology into a different sphere of potential manufacturing and revenue streams. There are a number of key areas within which bioprinting may convey a paradigm shift and alter the way in which companies, health-care providers, and consumers interact. Broadly speaking, some of these key areas involve tissue engineering of solid organ transplants, cosmetic and consumer testing, and drug discovery. Along with food and animal products, biosensors and implants, bioprinting has the potential to transform the way in which personalized manufacturing might shape and impact our lives over the next 30 years. In this chapter, we give a brief overview of the current global market, key areas of significant investment and growth, and discuss some of the companies leading the way in 3D bioprinting. The bioprinting landscape and key translational steps needed to deliver this technology to market will be discussed 3D Bioprinting for Reconstructive Surgery. https://doi.org/10.1016/B978-0-08-101103-4.00029-6 © 2018 Elsevier Ltd. All rights reserved.
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further and touching on future challenges, we discuss how these barriers might be overcome to ensure that the full potential of this novel technology is delivered.
20.2 The market Each of the bioprinting companies on the market, whether developing their own platform technology or adapting the existing hardware, uses one of the four main print-head technologies: extrusion, laser-induced forward transfer (LIFT), inkjet, and microvalve [7–14]. Between 2014 and 2015, the 3D bioprinting market saw the entry of a number of new companies, start-ups, spinouts, and subsidiaries all vying for a place in this developing field. Investment and initial valuations have been driven by future promises and early demonstration of potential application of their bioprinting technology [15,16]. As such it is difficult to estimate the value of these companies who all promise target delivery of printed tissue first with astronomical revenue potential.
20.2.1 3D printing: The evolution of the base technology To put 3D bioprinting into context, it is important to understand the development of the 3D printing and additive manufacturing (AM) industry over the last 30 years. In 2013, it was estimated that this market was worth around $1.3 billion with forecasts that would rise to between $4 and 6 billion by 2018 [16,17]. A number of major companies have announced a significant investment into 3D printing and AM in the last 2 years. Stryker announced in January 2016 that it would spend nearly $400 million building an AM facility for the production of implants, with Siemens in Sweden, and UK-based Metalysis investing €21.4 and £20 million, respectively, in printing technology and infrastructure [16]. Comparably 3D bioprinting is still in its infancy; however, market and tech forecast of leading companies suggest that ultimately the market will be measured in the tens of billions of dollars with an initial value of around $1.8 billion achieved by 2027 [15]. With the introduction of a new technology there is variable uptake and a need for significant and sustained investment in addition to a fundamental consumer need or perceived gap, which must exist for a product to be fully integrated into the marketplace. Each year Gartner produces its technology maturation curve or the “hype cycle” for new and emerging technologies as a way of informing the market and separating fleeting technologies from those, which are commercially viable with transformational potential. Cycling through the initial interest and influx of investment during the primary phase of innovation trigger, technologies must weather the peak of inflated expectation through the trough of disillusionment before emerging into the plateau of productivity. 3D bioprinting has relied on the success of 3D printing to garner interest and investment. Hype for the base technology, which was developed in the 1980s really began in 2014 when the first industrial-grade 3D printers entered the marketplace and demonstrated that it was possible to print in high-definition resin or metal [18]. The consumer market responded with smaller “desktop” printers shortly after, which
The commercial 3D bioprinting industry415 Advanced analytics with self-service delivery Autonomous vehicles Internet of things Speech-to-speech translation Machine learning Wearables Cryptocurrencies Consumer 3D printing Natural-language question answering
Expectations Smart advisors Microdata centers Digital dexterity Software-defined security Neurobusiness Citizen data science Biochips loT platform Connected home Affective computing Smart robots 3D bioprinting systems for organ transplant Volumetric displays Human augmentation Brain-computer interface Quantum computing
Hybrid cloud computing
Enterprise 3D printing
Augmented reality
Gesture control Bioacoustic sensing People-literate technology Digital security
Virtual reality Autonomous field vehicles
Cryptocurrency exchange Virtual personal assistants Smart dust
Innovation trigger
Peak of inflated expectations
As of July 2015 Trough of disillusionment
Slope of enlightenment
Plateau of productivity
Time Plateau will be reached in: <2 years
2–5 years
5–10 years
more than 10 years
Obsolete before plateau
Fig. 20.1 2015 Hype cycle for emerging technologies demonstrating the position of 3D printing having peaked the previous year, now heading toward the trough of disillusionment [19].
was made possible by the expiration of a number of key patents detailing the original 3D printing process. The consumer demand for the technology increased exponentially as did the applications in medical device and implants resulting in a spike in unit production [18]. The lack of surrounding infrastructure however, complexity of programming, and poor user interface meant that the consumers were left disillusioned and the initial investment wavered meaning that only a year later it was on the downward slope [19] (Fig. 20.1). In the 24 months that followed, however, a number of companies including P&G, HP, and GE have all invested heavily in 3D printing and bioprinting as expectations have been reset and the application of this technology has focused on the industrial and commercial applications within the marketplace. 3D printing is expanding commercially with scale no longer being a barrier, most recently demonstrated by the San Francisco-based start-up Apis Cor, who printed an entire house in 24 h [20]. Similarly, bioprinting has now become a key investment priority for Big Pharma, medical devices, and cosmetic companies, which has seen the technology diverge from traditional printing, and coupled with biological advancements in cell source and scaffold material creates opportunities to meet potentially significant gaps in the market.
20.2.2 Bioprinting: The gap in the market Initially focusing on the commercial and industrial market it becomes possible to identify strategic gaps, which create a potential opportunity for bioprinting companies. The cost of drug development is becoming prohibitively expensive and stricter guidance around animal testing means that the pharmaceutical and cosmetic
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c ompanies are looking for more cost-effective alternatives without compromising results. Procter and Gamble (P&G) has already banned animal testing on all but the 20% of its products which require it by law [21] mandating an alternative approach to product testing. In health care, waiting lists for patients on long-term dialysis or approaching end-stage liver failure present an economic health burden felt by every health system in the world. Tissue engineering promises the creation of solid organ transplants that would save thousands each year and lift the chronic health burden. In addition, tissue engineering holds the potential to restore form and function to patients born with congenital deformity or who acquire it later in life secondary to trauma or malignancy. Bioprinting companies have recognized the opportunity to supply the health-care sector with personalized tissue-engineered constructs and the investment is reflected in the development of advanced printer systems and the creation of novel biomaterials [1,22–24].
20.2.2.1 Tissue engineering Tissue engineering is a promising technology but not as mature as the cellular therapy sector. Replacement of damaged or missing tissue in pursuit of restoration of form and function is the holy grail of tissue engineering. An interdisciplinary field, it relies on an optimized cell source, scaffold, and printing technology to create de novo tissue fit-for-purpose. A decade on from the Vacanti mouse, we saw the first report of a tissue-engineered organ (bladder) being implanted into a patient [25]. Since then, the technology has advanced significantly and several organs and tissues have been engineered and implanted into patients; however, the materials engineering and cell biology require further work [26]. Flat structures such as the skin, which are the most efficient to engineer, have seen the most progress and examples of technology being offered to patients for wound healing include Integra (collagen scaffolds) as well as cellular matrices such as Apligraft. Bioprinting is a platform technology that has the potential to expand the tissue engineering field by allowing production of more complex tissues for reconstructive surgery using the bottom-up approach rather than decellularizing the existing structures. Bioprinting firms have diversified to include a range of cell source, scaffold material, and printing techniques in order to address some of the key hurdles and translational steps, but the same fundamental scientific questions exist to allow production of native-like tissues.
20.2.2.2 Organ transplant With the development of intelligent bioinks, novel scaffold materials, and diverse cell sources, 3D bioprinting has the potential to answer a number of clinical and research-based questions. Significant commercial potential lies within the field of tissue engineering and the creation of bioprinted 3D solid organs. The need for organ donation globally presents a set of unique challenges that mean an ever-increasing population of patients are waiting for a donor match. In 2014 more than 119,000 transplants were performed worldwide, an increase of almost 2% from the year previously and desperately short of total global need accounting for <10% of all transplant patients
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waiting [27]. The current system is a resource-intensive service, which has been under increasing scrutiny in the environment of austerity and economic constraints [28]. The promise to eliminate the waiting time, need for immunosuppression, and a donor-matched organ has attracted significant financial, research, and technological investment with the potential to change lives significantly [29–32]. In current tech reports which are forecasting into the late 2020s, it is theorized that this technology may be achievable within our lifetimes. However, it is more likely that simple structural tissues such as the cartilage and bone used in reconstructive surgeries will be some of the first transplanted due to the inherent complexity in architecture and function of solid organs which is more difficult to reproduce. A 30-year horizon view estimates that it is conceivable that the health-care burden created by organ transplant will be substantially reduced with issues revolving around a route to market, up-scaling production to meet complex global demand, and regulation of manufacturing and implantation quality control [15,33].
20.2.2.3 Drug development Drug discovery is a highly expensive and resource-heavy process that often results in failure to reach market and clear final regulatory hurdles due to lack of sufficient preclinical data, which accurately demonstrates the testing methodologies [33]. With the estimated cost of a new drug to market at around $2.6 billion, reliance on animal testing and 2D human cell assays is often a poor substitute for the human model and results in a significant cost to the pharmaceutical company [34]. In 2014, the bioprinting company Organovo's first product to market was a 3D-bioprinted liver assay which survived for 40 days and allowed more accurate toxicity testing and metabolic studies of pharmaceuticals [35]. With more companies now offering 3D-bioprinted tissue models including liver, kidney, lung, and thyroid, drug companies are better positioned to complete early phase testing before applying to proceed into first-phase human trials.
20.2.2.4 Cosmetic testing In 2013, the European Union issued a ban covering both the testing of cosmetic products and ingredients on animals, and bringing to market any product which had been tested on animals [36]. While the ban on cosmetic component testing had been in effect since 2009, the ban on testing finished cosmetics came into effect the following year in September 2014. This raised a number of issues with cosmetic companies manufacturing and selling their products within the EU. To address this, companies such as L'Oreal have turned to 3D bioprinting as part of the solution. In 2013, in advance of the ban enforcement, it had set up a partnership with Organovo to create skin models for cosmetic testing [21,33]. Organovo was able to print live cells at a cellular concentration of 100% creating the skin models required to gain essential information during the process of product development. Proctor & Gamble has also set up a $44 million fund as part of a wider 5-year research plan to invite researchers (primarily in Singapore) to submit proposals and bring bioprinting expertise into P&G. As the 3D models printed become more robust, the scope of testing will increase, significantly reducing the need for external testing, while meeting the legal and ethical obligations required [2,37,38].
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20.3 Key companies With a market expected to be worth around $1.8 billion by 2027, it is understandable that each year more companies are entering the market and established 3D printing companies are expanding to offer bioprinters and hardware to support this emerging field. Broadly speaking, companies are diverging into one of the two categories: focusing on the printers and support for the physical machinery with and without bioink supply, and those focusing on the production of 3D-bioprinted products such as skin models, assays, and tissue for cosmetic and drug testing. Companies with more than a decade of 3D printing experience such as EnvisionTEC have diversified and are now manufacturing bioprinters for biofabrication and implants which cost just under $200,000 which have been available since the early 2000s. They have an established supply chain and are simply adapting existing technology to “keep up” with the changing landscape while maintaining their core business,continuing to supply 3D printers to a number of commercial and industrial sectors. Start-ups focusing solely on 3D bioprinting such as BioBots which was founded by two friends at the University of Pennsylvania in 2013 have already developed two versions of their desktop 3D bioprinter, the latest of which costs around $5000. In 2015, they raised $1.5 million in funding and with more than 100 units of their BioBot 1 printer sold, they have made an estimated $1 million in revenue to date [39]. The concept is clear; they are offering an accessible entry-level product, which allows smaller research institutions to buy the technology into their organizations without any significant research investment. By providing on-going tech-support BioBots are able to access a wealth of free user data as it refines its technology ready for the next model to be released. In addition, they produce a range of support and sacrificial biopinks to use specifically in their machines; conceivably, you only need to add the cellular component and you are ready to go. There are a number of spin offs such as OxSyBio from Oxford University whose aim is to develop 3D printing techniques to produce a functional range of tissues for the repair and replacement of organs and skin. Although they raised £1 million in 2015 from the IP Group PLC to develop their proprietary droplet printing technology they are still in the research phase and as of yet do not have a product to take to market. Another company, CELLINK, initially focused on developing bioinks for extrusion bioprinting, is now expanding into producing bioprinters aimed at life science companies and researchers. Despite the substantial investment to date, many of the more strategically placed companies are yet to post significant profits, rather generating revenues from research grants and kick-starter or open platform fundraising. Organovo, the only publically traded bioprinting company, generated huge interest when it first went public and at one point trading at an estimated value of $1 billion despite having generated minimal profit. There is a fine balance however, and after their CEO and cofounder Keith Murphy left in April 2017 their share price bore the brunt, falling nearly 8% in the hours following the announcement. Their new CEO Taylor Crouch has previous experience with eStudySite, which in part conducted clinical trials, will be essential as Organovo aims to bring more of its bioprinted products to market and boost its revenue streams. It is important however to bear in mind that without extensive track records or significant profits, all bioprinting companies, public
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or privately owned, rely on the hype and promise of what is to come. The key will be sustaining the interest and investment while the technology catches up with the imagination and aspirations of the commercial markets.
20.4 Translational steps The refinement of current technologies will be an essential part of the progression not only of the technology but also of the logistical process, which will support the product to market. Regardless of the estimated value of these innovative tech start-ups, all they need is a sustainable way of generating revenue in the medium to long term by reliably bringing a product to market. No product can get to market without a robust end-to-end supply chain and as the technology develops, so too the regulation and infrastructure that surrounds this new technology. Regulatory boards that monitor and manage implantable devices will be quick to halt any process, which does not meet the standards designed to protect patient safety and guarantee traceability. Large-scale production to meet regional, national, or international demand must also be considered, with raw materials, processes, and storage not generating a total item cost that would put it beyond the reach of most health-care systems.
20.5 Future development Incremental advancements in 3D printing technology are getting ever smaller as the techniques are refined and the market place becomes more crowded. At some point producing a smaller printer will no longer be enough to gain market share and reliability along with a range of scaffolds and more diverse cell sources will become the economic differentiators. Market analysts are already talking about the next evolution within bioprinting, hinting that the addition of an extra dimension will alter the way in which bioprinting is ultimately utilized [40]. 4D printing hints at advanced technology that allows printed constructs or implants to respond to their environment promising wearable or implantable technology that adapts to the underling host system, external signal, or disease process [41–44]. The 3D bioprinting field offers unprecedented opportunity to change the paradigm in health care, but requires significant investment as well as the conviction to push the research through to clinical translation.
References [1] Chia HN, Wu BM. Recent advances in 3D printing of biomaterials. J Biol Eng 2015;9(1):1728. [2] Vijayavenkataraman S, Lu WF, Fuh JYH. 3D bioprinting of skin: a state-of-the-art review on modelling, materials, and processes. Biofabrication 2016;8(3):032001. [3] Hsieh FY, Lin HH, Hsu S. 3D bioprinting of neural stem cell-laden thermoresponsive biodegradable polyurethane hydrogel and potential in central nervous system repair. Biomaterials 2015;71:48–57.
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[4] Ventola CL. Medical applications for 3D printing: current and projected uses. P T 2014;39:704–11. [5] Prakash BB. 3D printing and its applications. Int J Sci Res 2016;5(3):1532–5. [6] Nale SB, Kalbande AG. A review on 3D printing technology. Int J Innov Emerg Res Eng 2015;2(9):33–6. [7] Gudapati H, Dey M, Ozbolat I. A comprehensive review on droplet-based bioprinting: past, present and future. Biomaterials 2016;102:20–42. [8] Ng WL, Yeong WY, Naing MW. Microvalve bioprinting of cellular droplets with high resolution and consistency. Proceedings of the 2nd international conference on progress in additive manufacturing (Pro-AM 2016); 2016. p. 397–402. [9] Catros S, Fricain JC, Guillotin B, Pippenger B. Laser-assisted bioprinting for creating on-demand patterns of human osteoprogenitor cells and nano-hydroxyapatite. Biofabrication 2011;3:025001. IOPscience. [10] Xu T, Jin J, Gregory C, Hickman JJ, Boland T. Inkjet printing of viable mammalian cells. Biomaterials 2005;26(1):93–9. [11] Arai K, Iwanaga S, Toda H, Genci C, Nishiyama Y, Nakamura M. Three-dimensional inkjet biofabrication based on designed images. Biofabrication 2011;3(3):034113. [12] Roth EA, Xu T, Das M, Gregory C, Hickman JJ, Boland T. Inkjet printing for high- throughput cell patterning. Biomaterials 2004;25(17):3707–15. [13] Michael S, Sorg H, Peck C-T, Koch L, Deiwick A, Chichkov B, et al. Tissue engineered skin substitutes created by laser-assisted bioprinting form skin-like structures in the dorsal skin fold chamber in mice. PLoS One 2013;8(3):e57741. [14] Lee JM, Yeong WY. Design and printing strategies in 3D bioprinting of cell-hydrogels: a review. Adv Healthc Mater 2016;5(22):2856–65. [15] Tsao N. 3D Bioprinting 2017-2027: technologies, markets, forecasts. www.idtechex. com; 2017. Available from: http://www.idtechex.com/research/reports/3d-bioprinting2017-2027-technologies-markets-forecasts-000537.asp [cited 16 September 2016]. [16] Associates W. Additive manufacturing: the state of the industry. Wohlers Report; 2016 Aprïl p. 1–6. [17] Gonzalez EE, la Cerda de R. Quo Vadis; 2015. p. 6. Available from: https://www.pwc. com/mx/es/industrias/archivo/2015-04-quovadis.pdf [cited 24 July 2017]. [18] Hilkene C. 3D printing in 2017: moving past disillusionment and into production applications. www.idtechex.com; 2017. Available from: https://www.ame.org/target/articles/ 2017/3d-printing-2017-moving-past-disillusionment-and-production-applications [cited 25 July 2017]. [19] Gartner. Gartner's 2015 Hype cycle for emerging technologies identifies the computing innovations that organizations should monitor; 2015. Available from: http://www.gartner. com/newsroom/id/3114217 [cited 27 July 2017]. [20] Apis Cor. The first on-site house has been printed in Russia. www.apis-cor.com; 2017. Available from: http://apis-cor.com/en/about/news/first-house [cited 21 July 2017]. [21] Gordon R. P&G, L'Oreal push 3D bioprinting from research to commercial products. www.idtechex.com. Available from: http://www.idtechex.com/research/articles/p-g- loreal-push-3d-bioprinting-from-research-to-commercial-products-00007888.asp?donotredirect=true [cited 27 July 2017]. [22] Chen F-M, Liu X. Advancing biomaterials of human origin for tissue engineering. Prog Polym Sci 2016;53:86–168. [23] Zhang YS, Arneri A, Bersini S, Shin SR, Zhu K, Goli-Malekabadi Z, et al. Bioprinting 3D microfibrous scaffolds for engineering endothelialized myocardium and heart-on-achip. Biomaterials 2016;110:45–59.
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[24] Lee J-S, Hong JM, Jung JW, Shim J-H, Oh J-H, Cho D-W. 3D printing of composite tissue with complex shape applied to ear regeneration. Biofabrication 2014;6(2):024103. [25] Atala A, Bauer SB, Soker S, Yoo JJ, Retik AB. Tissue-engineered autologous bladders for patients needing cystoplasty. Lancet 2006;367(9518):1241–6. [26] Vacanti CA, Cima LG, Ratkowski D, Upton J, Vacanti JP. Tissue engineered growth of new cartilage in the shape of a human ear using synthetic polymers seeded with chondrocytes. MRS Proc 2011;252:475. [27] Reports 2014—GODT. 2016. Available from: http://www.transplant-observatory.org/ data-reports-2014/. [28] Axelrod DA. Economic and financial outcomes in transplantation. Curr Opin Organ Transplant 2013;18(2):222–8. [29] Mironov V, Boland T, Trusk T, Forgacs G. Organ printing: computer-aided jet-based 3D tissue engineering. Trends Biotechnol 2003;21(4):157–61. [30] Marx V. Tissue engineering: organs from the lab. Nature 2015;522(7556):373–7. [31] Marga F, Jakab K, Khatiwala C, Shepherd B, Dorfman S, Hubbard B, et al. Toward engineering functional organ modules by additive manufacturing. Biofabrication 2012;4(2):022001. [32] Murphy SV, Atala A. 3D bioprinting of tissues and organs. Nat Biotechnol 2014;32(8):773– 85. Nature Publishing Group. [33] IDTechX. 3D Bioprinting 2014-2024: Applications, Markets, Players. www.idtechex. com; 2015. p. 1–104. Available from: http://www.idtechex.com/research/articles/3d-bioprinting-2014-2024-applications-and-markets-00006479.asp?donotredirect=true [cited 26 July 2017]. [34] Mullard A. New drugs cost US$2.6 billion to develop. Nat Rev Drug Discov 2014;13(12):877. [35] Murphy K. Organovo’s bioprinting platform: enabling 3D, architecturally correct, fully human tissue for drug discovery and transplantation. Organovo. Available from: http:// organovo.com/cell-gene-meeting-mesa/ [cited 27 July 2017]. [36] European Commision. Ban on animal testing. European Commision; 2013. Available from: https://ec.europa.eu/growth/sectors/cosmetics/animal-testing_en [cited 20 July 2017]. [37] Velasquillo C, Galue EA, Rodriquez L, Ibarra C. Skin 3D bioprinting. J Cosmet Dermatol Sci Appl 2013;3:85–9. [38] Cubo N, Garcia M, del Cañizo JF, Velasco D, Jorcano JL. 3D bioprinting of functional human skin: production and in vivo analysis. Biofabrication 2016;9(1):1–12. IOP Publishing. [39] Dill K. Inside the company that wants to put a $10,000 3D bioprinter on every lab bench. Forbes; 2016. Available from: https://www.forbes.com/sites/kathryndill/2016/11/02/inside-the-company-that-wants-to-put-a-10000-3d-bioprinter-on-everylab-bench/#3e961f4edf30 [cited 21 July 2017]. [40] Panetta K. 3 Trends appear in the gartner hype cycle for emerging technologies; 2016. Available from: http://www.gartner.com/smarterwithgartner/3-trends-appear-in-the- gartner-hype-cycle-for-emerging-technologies-2016/ [cited 22 July 2017]. [41] Li Y-C, Zhang YS, Akpek A, Shin SR, Khademhosseini A. 4D bioprinting: the next-generation technology for biofabrication enabled by stimuli-responsive materials. Biofabrication 2016;9(1):012001. [42] Gao B, Yang Q, Zhao X, Jin G, Ma Y, Xu F. 4D bioprinting for biomedical applications. Trends Biotechnol 2016;34(9):746–56. [43] An J, Chua CK, Mironov V. A perspective on 4D bioprinting. Int J Bioprint 2016;2:3–5. [44] Leist SK, Zhou J. Current status of 4D printing technology and the potential of light- reactive smart materials as 4D printable materials. Virtual Phys Prototyp 2016;11(4):249– 62. 1st ed., Taylor & Francis.