As I discussed Introductory part and some benefits of 3D-Bioprinting in the previous blog now I would like to emphasis of the Central approaches of 3D-bioprinting in Medical. So, Lets begin with three central approaches to bioprinting are biomimicry, autonomous self-assembly, and a microtissue-based method. These general strategies are not exclusive to bioprinting and are broadly applied to many investigational areas within the larger scope of regenerative medicine. In many cases, these are used for tissue engineering applications unrelated to bioprinting. However, a discussion of these fundamental strategies is necessary when considering the optimal approach to bioprinting objectives. Each of these may applied to specific bioprinting applications to varying degrees based on factors such as target tissue type, user experience, and printing method. It is not uncommon to combine strategies for more complex tissue types. I would to discuss each of these in detail below.
With the understanding that function will follow form, a biomimetic approach attempts to engineer each individual component of native tissue. While it is the most conceptually straightforward approach, it is extremely difficult to reproduce all elements that make up the milieu of a given target tissue. Even for relatively simple tissue types, the sheer volume and dynamic nature of cellular interactions that occur reach staggering complexity. In addition to the numerous cell types, signaling molecules, and structural elements within the tissue itself, all environmental factors including pressure, temperature, and electrical forces must be considered.4,5 As tissues become more complex, the 3D structure and resultant mechanical forces add yet more complexity.
The self-assembly approach attempts to replicate embryonic environmental and structural elements with the end goal of creating correct embryologic anatomy. Bioprinting may be utilized to produce these discrete units that can self-organize for tissue development. This strategy depends on the understanding that with the correct embryonic elements in place, development will recapitulate that seen in nature, with cells and supporting structures self organizing and interacting to create any other raw materials needed during development to mature tissue. This is distinct from the biomimetic approach in which an attempt is made to externally influence the maturation of a tissue at all stages of development. The autonomous self-assembly approach does not adhere to the traditional tissue engineering approach of seeding cells onto a scaffold but relies on the conceptual reasoning that tissues and organs have inherent mechanisms for development and often do not require a template or scaffold.
The concept of a microtissue approach to bioprinting relies on the fact that a typical complex in vivo tissue is composed of many simpler units whose combined structure and function contribute to the overall whole. In utilizing this strategy, tissue engineering techniques are used to form the smallest structural and functional units which can be combined into the final target tissue.1 The term mini tissues is often used interchangeably with the term microtissues by some investigators. When a microtissue based approach is used, the term macro tissue is typically used to distinguish fully developed tissue from its smaller constituent units. Microtissues are incorporated into bioink and consolidation to macro tissue occurs after printing. Self-assembly or biomimetic strategies may be used to facilitate this consolidation. There is a multifactorial effect on the speed and efficiency of the bioprinting process when using a microtissue based approach. First, the smaller size of microtissues are more easily incorporated into bioinks for bioprinting,a process that greatly increases the overall efficiency of the bioprinting process.
By using these many approaches their are numerous success stories and trials were performed across the globe, so now I would like to take you throgh those stories. Firstly, Three-year-old girl from Northern Ireland has become the first to have a life-saving adult kidney transplant, using 3D printing. At four months old, Lucy Boucher suffered heart failure which starved her kidneys of oxygen. She was told she would need to have kidney dialysis for life, until surgeons at London's Guy's and St Thomas' and Great Ormond Street Hospital performed the transplant. To conduct the transplant, for which Lucy's father Chris, 35, donated his kidney, the surgeons made detailed models of Mr Boucher's kidney and Lucy's abdomen with a 3D printer, so they could map out the procedure with precision, hence minimising risks. According to Guy's and St Thomas' NHS Foundation Trust: "It is the first time in the world that 3D printing has been used to aid kidney transplant surgery involving an adult donor and a child recipient." Mr Boucher said: "My first reaction when I saw the 3D printout of my kidney was surprise at how big it was and I wondered how it could possibly fit into Lucy. "Seeing the model of her abdomen and the way the kidney was going to be transplanted inside her gave me a clear understanding of exactly what was going to happen."Lucy's mother Ciara said: "We found it amazing that we could see these incredibly detailed models of Chris' kidney and Lucy's abdomen. "Considering all the potential complications, it's fantastic that everything has gone so well - it's a massive relief. The transplant is life-changing for Lucy."
Additionally, Vladimir Mironov’s 3D printed medical breakthrough: the world’s first 3D printed transplantable organ, to be used on a mouse. This week, it was reported that not only did the mouse thyroid transplant surgery go relatively smoothly, but that the 3D printed thyroid gland is completely functional. The news has exciting implications for the future of medicine, Russian scientists, along with the rest of the world, set their sights on 3D printing functional human organs next.
While most surgical applications of 3D printing technology are having very rare cases and strange deformities or injuries, some startups are also hard at work standardizing this customization process for hospitals everywhere. One of the most successful is the British startup Embody Orthopaedic of Dr Susannah Clarke, which has used 3D printing to develop a system for manufacturing custom 3D printed instruments and surgical models to be used in knee and hip surgeries. Having extensively tested them in hundreds of surgeries in the Charing Cross Hospital in London, Clarke and Embody Orthopaedic are now ready to expand their services to hospitals across Britain.
Moreover, A 22-year-old woman from the Netherlands who suffers from a chronic bone disorder -- which has increased the thickness of her skull from 1.5cm to 5cm, causing reduced eyesight and severe headaches -- has had the top section of her skull removed and replaced with a 3D printed implant. The operation was performed by a team of neurosurgeons at the University Medical Centre Utrecht and the university claims this is this first instance of a successful 3D printed cranium that has not been rejected by the patient.The operation, which took 23 hours, was led by Dr Bon Verweij. The patient's skull was so thick, that had the operation not been performed, serious brain damage or death may have occurred in the near future. "It was only a matter of time before critical brain functions were compromised and she would die," said Dr Verweij. Major surgery was inevitable, but prior to the 3D printing technique, there was no ideal effective treatment. The skull was made specifically for the patient using an unspecified durable plastic. Since the operation, the patient has gained her sight back entirely, is symptom-free and back to work. It is not known whether the plastic will require replacing at a later date or if it will last a lifetime.
Altogether,Medical 3D printing centres of excellence, technical recommendations stratified by clinical
application will be determined regarding the imaging data acquisition,
postprocessing, 3D printing technologies, and materials used. The
additive benefit of 3D printing for each application under investigation
will be established by the effect on patient care, routine clinical
practice, patient–physician
communication, society, and economy, as well as the cost-effectiveness
of the technology. Such clinical trials will potentially lead to the
implementation of medical 3D printing in treatment guidelines and
recommendations.
References:
1. Tanveer ahmad mir et al., tissue engineering: part b volume 23, number 3, 2017
2. Andreas Giannopoulos, Applications of 3D printing in cardiovascular diseases, Nature Reviews Cardiology 13(12) · October 2016.
3. Murphy SV, Atala A. 3D bioprinting of tissues and organs. Nat Biotechnol. 2014;32(8):773e785.
4. Irvine SA, Venkatraman SS. Bioprinting and differentiation of stem cells. Molecules. 2016;21(9). pii: E1188.
5. Gao G, Cui X. Three-dimensional bioprinting in tissue engineering and regenerative medicine. Biotechnol Lett. 2016; 38(2):203e211.
6. Ingber DE, Mow VC, Butler D, et al. Tissue engineering and developmental biology: going biomimetic. Tissue Eng. 2006; 12(12):3265e3283.
7.Grayson WL, Martens TP, Eng GM, Radisic M, Vunjak- Novakovic G. Biomimetic approach to tissue engineering. Semin Cell Dev Biol. 2009;20(6):665e673.
8. Huang Y, Zhang XF, Gao G, Yonezawa T, Cui X. 3D bioprinting and the current applications in tissue engineering. Biotechnol J. 2017;12(8). https://doi.org/10.1002/biot.201600734.
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