Print Me an Organ? Ethical and Regulatory Issues Emerging from 3D Bioprinting in Medicine

[3D printing in surgery: relevance of technology maturity assessment in bioprinting research studies]

Biological 3D printing (bioprinting) is an extension of what is defined as additive manufacturing in the American Society for Testing and Materials (ASTM) and International Organization for Standardization (ISO) standards and is based on the automated printing of living cells and biomaterials. Researchers and experts in the field of biomaterial science, tissue engineering and regenerative medicine (TE&RM) are constantly pointing to the potential of biological 3D printing and scientific articles regularly announce the imminent clinical application. We argue in this article that these announcements are often premature and counterproductive as they focus heavily on technological progress but regularly ignore the critical stages that need to be completed in order to successfully translate a technology into the healthcare market. The technology readiness level (TRL) scale is a potentially useful tool for measuring the relative maturity of a technology in terms of overcoming a series of critical milestones. We propose an adaptation of the TRL scale and use it to discuss the current state of research on biological 3D printing. Finally, we provide specific recommendations for optimizing future research projects to pave the way for clinical applications of biological 3D printing and thus achieve a direct positive impact on surgical patient care.

Harnessing native blueprints for designing bioinks to bioprint functional cardiac tissue

Cardiac tissue lacks regenerative capacity, making heart transplantation the primary treatment for end-stage heart failure. Engineered cardiac tissues developed through three-dimensional bioprinting (3DBP) offer a promising alternative. However, reproducing the native structure, cellular diversity, and functionality of cardiac tissue requires advanced cardiac bioinks. Major obstacles in CTE (cardiac tissue engineering) include accurately characterizing bioink properties, replicating the cardiac microenvironment, and achieving precise spatial organization. Optimizing bioink properties to closely mimic the extracellular matrix (ECM) is essential, as deviations may result in pathological effects. This review encompasses the rheological and electromechanical properties of bioinks and the function of the cardiac microenvironment in the design of functional cardiac constructs. Furthermore, it focuses on improving the rheological characteristics, printability, and functionality of bioinks, offering valuable perspectives for developing new bioinks especially designed for CTE.

Extrusion bioprinting: meeting the promise of human tissue biofabrication?

Extrusion is the most popular bioprinting platform. Predictions of human tissue and whole-organ printing have been made for the technology. However, after decades of development, extruded constructs lack the essential microscale resolution and heterogeneity observed in most human tissues. Extrusion bioprinting has had little clinical impact with the majority of research directed away from the tissues most needed by patients. The distance between promise and reality is a result of technology hype and inherent design flaws that limit the shape, scale and survival of extruded features. By more widely adopting resolution innovations and softening its ambitions the biofabrication field could define a future for extrusion bioprinting that more closely aligns with its capabilities.

Material-Mediated Immunotherapy to Regulate Bone Aging and Promote Bone Repair

As the global population ages, an increasing number of elderly people are experiencing weakened bone regenerative capabilities, resulting in slower bone repair processes and associated risks of various complications. This review outlines the research progress on biomaterials that promote bone repair through immunotherapy. This review examines how manufacturing technologies such as 3D printing, electrospinning, and microfluidic technology contribute to enhancing the therapeutic effects of these biomaterials. Following this, it provides detailed introductions to various anti-osteoporosis drug delivery systems, such as injectable hydrogels, nanoparticles, and engineered exosomes, as well as bone tissue engineering materials and coatings used in immunomodulation. Moreover, it critically analyzes the current limitations of biomaterial-mediated bone immunotherapy and explores future research directions for material-mediated bone immunotherapy. This review aims to inspire new approaches and broaden perspectives in addressing the challenges of bone repair and aging by exploring innovative biomaterial-mediated immunotherapy strategies.

3D bioprinting for the construction of drug testing models-development strategies and regulatory concerns

A drug to be successfully launched in the market requires a significant amount of capital, resources and time, where the unsuccessful results in the last stages lead to catastrophic failure for discovering drugs. This is the very reason which calls for the invention of innovative models that can closely mimic the human in vivo model for producing reliable results. Throughout the innovation line, there has been improvement in the rationale in silico designing but yet there is requirement for in vitro-in vivo correlations. During the evolving of the drug testing models, the 3D models produced by different methods have been proven to produce better results than the traditional 2D models. However, the in vitro fabrications of live tissues are still bottleneck in realizing their complete potential. There is an urgent need for the development of single, standard and simplified in vitro 3D tissue models that can be reliable for investigating the biological and pathological aspects of drug discovery, which is yet to be achieved. The existing pre-clinical models have considerable drawbacks despite being the gold standard in pre-clinical research. The major drawback being the interspecies differences and low reliability on the generated results. This gap could be overcome by the fabrication of bioengineered human disease models for drug screening. The advancement in the fabrication of 3D models will provide a valuable tool in screening drugs at different stages as they are one step closer to bio-mimic human tissues. In this review, we have discussed on the evolution of preclinical studies, and different models, including mini tissues, spheroids, organoids, bioengineered three dimensional models and organs on chips. Furthermore, we provide details of different disease models fabricated across various organs and their applications. In addition to this, the review also focuses on the limitations and the current prospects of the role of three dimensionally bioprinted models in drug screening and development.

Advances in three-dimensional printing of hydrogel formulations for vascularized tissue and organ regeneration

Over the last decades, three-dimensional (3D) printing has emerged as one of the most promising alternative tissue and organ regeneration technologies. Recent advances in 3D printing technology, particularly in hydrogel-derived bioink formulations, offer promising solutions for fabricating intricate, biomimetic scaffolds that promote vascularization. In this review, we presented numerous studies that have been conducted to fabricate 3D-printed hydrogel vascularized constructs with significant advancements in printing integumentary systems, cardiovascular systems, vascularized bone tissues, skeletal muscles, livers, and kidneys. Furthermore, this work also discusses the engineering considerations, current challenges, proposed solutions, and future outlooks of 3D bioprinting.

Three-Dimensional Printing/Bioprinting and Cellular Therapies for Regenerative Medicine: Current Advances

The application of three-dimensional (3D) printing/bioprinting technologies and cell therapies has garnered significant attention due to their potential in the field of regenerative medicine. This paper aims to provide a comprehensive overview of 3D printing/bioprinting technology and cell therapies, highlighting their results in diverse medical applications, while also discussing the capabilities and limitations of their combined use. The synergistic combination of 3D printing and cellular therapies has been recognised as a promising and innovative approach, and it is expected that these technologies will progressively assume a crucial role in the treatment of various diseases and conditions in the foreseeable future. This review concludes with a forward-looking perspective on the future impact of these technologies, highlighting their potential to revolutionize regenerative medicine through enhanced tissue repair and organ replacement strategies.

Bioprinting and Intellectual Property: Challenges, Opportunities, and the Road Ahead

Bioprinting, an innovative combination of biotechnology and additive manufacturing, has emerged as a transformative technology in healthcare, enabling the fabrication of functional tissues, organs, and patient-specific implants. The implementation of the aforementioned, however, introduces unique intellectual property (IP) challenges that extend beyond conventional biotechnology. The study explores three critical areas of concern: IP protection for bioprinting hardware and bioinks, ownership and ethical management of digital files derived from biological data, and the implications of commercializing bioprinted tissues and organs. Employing a multidisciplinary approach, the paper analyzes existing IP frameworks, highlights their limitations when applied to bioprinting, and examines ethical dilemmas, such as ownership of bioprinted human tissues and the commodification of biological innovations. Findings suggest that current IP laws inadequately address the complexities of bioprinting, particularly in managing the intersection of proprietary technologies and ethical considerations. The study underscores the need for adaptive legal and ethical frameworks to balance innovation with equitable access and sustainability. Recommendations include the development of tailored IP policies for bioprinting and enhanced international collaboration to harmonize legal protections across jurisdictions. This work aims to provide a comprehensive foundation for stakeholders to navigate the rapidly evolving landscape of bioprinting IP.

Why bioprinting in regenerative medicine should adopt a rational technology readiness assessment

Bioprinting is an annex of additive manufacturing, as defined by the American Society for Testing and Materials (ASTM) and International Organization for Standardization (ISO) standards, characterized by the automated deposition of living cells and biomaterials. The tissue engineering and regenerative medicine (TE&RM) community has eagerly adopted bioprinting, while review articles regularly herald its imminent translation to the clinic as functional tissues and organs. Here we argue that such proclamations are premature and counterproductive; they place emphasis on technological progress while typically ignoring the critical stage-gates that must be passed through to bring a technology to market. We suggest the technology readiness level (TRL) scale as a valuable metric for gauging the relative maturity of a bioprinting technology in relation to how it has passed a series of key milestones. We suggest guidelines for a bioprinting-oriented scale and use this to discuss the state-of-the-art of bioprinting in regenerative medicine (BRM) today. Finally, we make corresponding recommendations for improvements to BRM research that would support its progression to clinical translation.

Patient, parent and professional expert perspectives on personalized regenerative implants: a qualitative focus group study

Background: Perspectives of patients, parents and professional experts on personalized regenerative implants for regenerative medicine purposes are largely unknown.Method: To better understand these perspectives, we conducted four focus groups with professional experts of mixed European nationality (n = 8), Dutch patients with regular implants (n = 8), Dutch and Belgian (n = 5) and Spanish (n = 8) parents of children with cleft palate.Results: Two overarching themes were identified: 'patient-centered research and care' and 'ambivalent attitudes toward personalized regenerative implants'.Discussion: The results reveal that stakeholders should adopt a participatory rather than an impairment discourse and address the ambivalence among professional experts, patients and parents.Conclusion: Considering stakeholder perspectives facilitates ethical and responsible development and use of personalized regenerative implants.

Three-Dimensional Bioprinting: A Comprehensive Review for Applications in Tissue Engineering and Regenerative Medicine

Since three-dimensional (3D) bioprinting has emerged, it has continuously to evolved as a revolutionary technology in surgery, offering new paradigms for reconstructive and regenerative medical applications. This review highlights the integration of 3D printing, specifically bioprinting, across several surgical disciplines over the last five years. The methods employed encompass a review of recent literature focusing on innovations and applications of 3D-bioprinted tissues and/or organs. The findings reveal significant advances in the creation of complex, customized, multi-tissue constructs that mimic natural tissue characteristics, which are crucial for surgical interventions and patient-specific treatments. Despite the technological advances, the paper introduces and discusses several challenges that remain, such as the vascularization of bioprinted tissues, integration with the host tissue, and the long-term viability of bioprinted organs. The review concludes that while 3D bioprinting holds substantial promise for transforming surgical practices and enhancing patient outcomes, ongoing research, development, and a clear regulatory framework are essential to fully realize potential future clinical applications.

Strategies for developing 3D printed ovarian model for restoring fertility

Ovaries play a crucial role in the regulation of numerous essential processes that occur within the intricate framework of female physiology. They are entrusted with the responsibility of both generating a new life and orchestrating a delicate hormonal symphony. Understanding their functioning is crucial for gaining insight into the complexities of reproduction, health, and fertility. In addition, ovaries secrete hormones that are crucial for both secondary sexual characteristics and the maintenance of overall health. A three-dimensional (3D) prosthetic ovary has the potential to restore ovarian function and preserve fertility in younger females who have undergone ovariectomies or are afflicted with ovarian malfunction. Clinical studies have not yet commenced, and the production of 3D ovarian tissue for human implantation is still in the research phase. The main challenges faced while creating a 3D ovary for in vivo implantation include sustenance of ovarian follicles, achieving vascular infiltration into the host tissue, and restoring hormone circulation. The complex ovarian microenvironment that is compartmentalized and rigid makes the biomimicking of the 3D ovary challenging in terms of biomaterial selection and bioink composition. The successful restoration of these properties in animal models has led to expectations for the development of human ovaries for implantation. This review article summarizes and evaluates the optimal 3D models of ovarian structures and their safety and efficacy concerns to provide concrete suggestions for future research.

Sculpting the future: A narrative review of 3D printing in plastic surgery and prosthetic devices

Background and Aims

The advent of 3D printing has revolutionized plastic surgery and prosthetic devices, providing personalized solutions for patients with traumatic injuries, deformities, and appearance-related conditions. This review offers a comprehensive overview of 3D printing's applications, advantages, limitations, and future prospects in these fields.

Methods

A literature search was conducted in PubMed, Google Scholar, and Scopus for studies on 3D printing in plastic surgery.

Results

3D printing has significantly contributed to personalized medical interventions, with benefits like enhanced design flexibility, reduced production time, and improved patient outcomes. Using computer-aided design (CAD) software, precise models tailored to a patient's anatomy can be created, ensuring better fit, functionality, and comfort. 3D printing allows for intricate geometries, leading to improved aesthetic outcomes and patient-specific prosthetic limbs and orthoses. The historical development of 3D printing, key milestones, and breakthroughs are highlighted. Recent progress in bioprinting and tissue engineering shows promising applications in regenerative medicine and transplantation. The integration of AI and automation with 3D printing enhances surgical planning and outcomes. Emerging trends in patient-specific treatment planning and precision medicine are potential game-changers. However, challenges like technical considerations, economic implications, and ethical issues exist. Addressing these challenges and advancing research in materials, design processes, and long-term outcomes are crucial for widespread adoption.

Conclusion

The review underscores the increasing adoption of 3D printing in healthcare and its impact on plastic surgery and prosthetic devices. It emphasizes the importance of evaluating the current state and addressing knowledge gaps through future research to foster further advancements.

Constructing appropriate bioprinting regulations: the ethical importance of recognising a liminal technology

This article provides an analysis of bioprinting personalised medical device technology and its ethical challenges to regulation and research ethics. I argue the inclusion of bioprinting applications within existing regulatory frameworks does not adequately address the technologies disruption to the traditionally siloed activities of research and treatment. Using the conceptual framework of liminality, I offer a meaningful way to engage with this technology and address some identified concerns with how it will be categorised and the appropriate recognition of its evidentiary thresholds. I demonstrate these concerns through the exploration of limited conventional research methodologies tasked with the production of generalisable knowledge, specifically population-based evidence that is derived from Randomised Clinical Trials. I use Australian regulatory amendments introduced in 2021 as an example of current regulatory trajectories and highlight why I believe this approach to be insufficient. The significance of this argument will be to demonstrate the disruption of bioprinting applications to current approaches in medical policy, and how various jurisdictions are enacting regulation that is not fit for purpose.

Personalized 3D printed scaffolds: The ethical aspects

Personalized 3D printed scaffolds are a new generation of implants for tissue engineering and regenerative medicine purposes. Scaffolds support cell growth, providing an artificial extracellular matrix for tissue repair and regeneration and can biodegrade once cells have assumed their physiological and structural roles. The ethical challenges and opportunities of these implants should be mapped in parallel with the life cycle of the scaffold to assist their development and implementation in a responsible, safe, and ethically sound manner. This article provides an overview of these relevant ethical aspects. We identified nine themes which were linked to three stages of the life cycle of the scaffold: the development process, clinical testing, and the implementation process. The described ethical issues are related to good research and clinical practices, such as privacy issues concerning digitalization, first-in-human trials, responsibility and commercialization. At the same time, this article also creates awareness for underexplored ethical issues, such as irreversibility, embodiment and the ontological status of these scaffolds. Moreover, it exemplifies how to include gender in the ethical assessment of new technologies. These issues are important for responsible development and implementation of personalized 3D printed scaffolds and in need of more attention within the additive manufacturing and tissue engineering field. Moreover, the insights of this review reveal unresolved qualitative empirical and normative questions that could further deepen the understanding and co-creation of the ethical implications of this new generation of implants.

Use of 3D Printing Techniques to Fabricate Implantable Microelectrodes for Electrochemical Detection of Biomarkers in the Early Diagnosis of Cardiovascular and Neurodegenerative Diseases

This Review provides a comprehensive overview of 3D printing techniques to fabricate implantable microelectrodes for the electrochemical detection of biomarkers in the early diagnosis of cardiovascular and neurodegenerative diseases. Early diagnosis of these diseases is crucial to improving patient outcomes and reducing healthcare systems' burden. Biomarkers serve as measurable indicators of these diseases, and implantable microelectrodes offer a promising tool for their electrochemical detection. Here, we discuss various 3D printing techniques, including stereolithography (SLA), digital light processing (DLP), fused deposition modeling (FDM), selective laser sintering (SLS), and two-photon polymerization (2PP), highlighting their advantages and limitations in microelectrode fabrication. We also explore the materials used in constructing implantable microelectrodes, emphasizing their biocompatibility and biodegradation properties. The principles of electrochemical detection and the types of sensors utilized are examined, with a focus on their applications in detecting biomarkers for cardiovascular and neurodegenerative diseases. Finally, we address the current challenges and future perspectives in the field of 3D-printed implantable microelectrodes, emphasizing their potential for improving early diagnosis and personalized treatment strategies.

Three-Dimensional Bioprinting of Human Organs and Tissues: Bioethical and Medico-Legal Implications Examined through a Scoping Review

Three-dimensional bioprinting is a rapidly evolving technology that holds the promise of addressing the increasing demand for organs, tissues, and personalized medicine. By employing computer-aided design and manufacturing processes, 3D bioprinting allows for the precise deposition of living cells, biomaterials, and biochemicals to create functional human tissues and organs. The potential applications of this technology are vast, including drug testing and development, disease modeling, regenerative medicine, and ultimately, organ transplantation. However, as with any groundbreaking technology, 3D bioprinting presents several ethical, legal, and regulatory concerns that warrant careful consideration. As the technology progresses towards clinical applications, it is essential to address these challenges and establish appropriate frameworks to guide the responsible development of 3D bioprinting. This article, utilizing the Arksey and O'Malley scoping review model, is designed to scrutinize the bioethical implications, legal and regulatory challenges, and medico-legal issues that are intertwined with this rapidly evolving technology.

The regulatory challenge of 3D bioprinting

New developments in additive manufacturing and regenerative medicine have the potential to radically disrupt the traditional pipelines of therapy development and medical device manufacture. These technologies present a challenge for regulators because traditional regulatory frameworks are designed for mass manufactured therapies, rather than bespoke solutions. 3D bioprinting technologies present another dimension of complexity through the inclusion of living cells in the fabrication process. Herein we overview the challenge of regulating 3D bioprinting in comparison to existing cell therapy products as well as custom-made 3D printed medical devices. We consider a range of specific challenges pertaining to 3D bioprinting in regenerative medicine, including classification, risk, standardization and quality control, as well as technical issues related to the manufacturing process and the incorporated materials and cells.

3D and 4D Bioprinting Technologies: A Game Changer for the Biomedical Sector?

Bioprinting is an innovative and emerging technology of additive manufacturing (AM) and has revolutionized the biomedical sector by printing three-dimensional (3D) cell-laden constructs in a precise and controlled manner for numerous clinical applications. This approach uses biomaterials and varying types of cells to print constructs for tissue regeneration, e.g., cardiac, bone, corneal, cartilage, neural, and skin. Furthermore, bioprinting technology helps to develop drug delivery and wound healing systems, bio-actuators, bio-robotics, and bio-sensors. More recently, the development of four-dimensional (4D) bioprinting technology and stimuli-responsive materials has transformed the biomedical sector with numerous innovations and revolutions. This issue also leads to the exponential growth of the bioprinting market, with a value over billions of dollars. The present study reviews the concepts and developments of 3D and 4D bioprinting technologies, surveys the applications of these technologies in the biomedical sector, and discusses their potential research topics for future works. It is also urged that collaborative and valiant efforts from clinicians, engineers, scientists, and regulatory bodies are needed for translating this technology into the biomedical, pharmaceutical, and healthcare systems.

A mechanically validated open-source silicone model for the training of gastric perforation sewing

BACKGROUND

Gastrointestinal perforation is commonly seen in emergency departments. The perforation of the stomach is an emergency situation that requires immediate surgical treatment. The necessary surgical skills require regular practical training. Owing to patient`s safety, in vivo training opportunities in medicine are restricted. Animal tissue especially porcine tissue, is commonly used for surgical training. Due to its limiting factors, artificial training models are often to be preferred. Many artificial models are on the market but to our knowledge, none that mimic the haptic- and sewing properties of a stomach wall at the same time. In this study, an open source silicone model of a gastric perforation for training of gastric sewing was developed that attempts to provide realistic haptic- and sewing behaviour.

METHODS

To simulate the layered structure of the human stomach, different silicone materials were used to produce three different model layups. The production process was kept as simple as possible to make it easily reproducible. A needle penetration setup as well as a systematic haptic evaluation were developed to compare these silicone models to a real porcine stomach in order to identify the most realistic model.

RESULTS

A silicone model consisting of three layers was identified as being the most promising and was tested by clinical surgeons.

CONCLUSIONS

The presented model simulates the sewing characteristics of a human stomach wall, is easily reproducible at low-costs and can be used for practicing gastric suturing techniques.

TRIAL REGISTRATIONS

Not applicable.

The Ethical Implications of Tissue Engineering for Regenerative Purposes: A Systematic Review

Tissue Engineering (TE) is a branch of Regenerative Medicine (RM) that combines stem cells and biomaterial scaffolds to create living tissue constructs to restore patients' organs after injury or disease. Over the last decade, emerging technologies such as 3D bioprinting, biofabrication, supramolecular materials, induced pluripotent stem cells, and organoids have entered the field. While this rapidly evolving field is expected to have great therapeutic potential, its development from bench to bedside presents several ethical and societal challenges. To make sure TE will reach its ultimate goal of improving patient welfare, these challenges should be mapped out and evaluated. Therefore, we performed a systematic review of the ethical implications of the development and application of TE for regenerative purposes, as mentioned in the academic literature. A search query in PubMed, Embase, Scopus, and PhilPapers yielded 2451 unique articles. After systematic screening, 237 relevant ethical and biomedical articles published between 2008 and 2021 were included in our review. We identified a broad range of ethical implications that could be categorized under 10 themes. Seven themes trace the development from bench to bedside: (1) animal experimentation, (2) handling human tissue, (3) informed consent, (4) therapeutic potential, (5) risk and safety, (6) clinical translation, and (7) societal impact. Three themes represent ethical safeguards relevant to all developmental phases: (8) scientific integrity, (9) regulation, and (10) patient and public involvement. This review reveals that since 2008 a significant body of literature has emerged on how to design clinical trials for TE in a responsible manner. However, several topics remain in need of more attention. These include the acceptability of alternative translational pathways outside clinical trials, soft impacts on society and questions of ownership over engineered tissues. Overall, this overview of the ethical and societal implications of the field will help promote responsible development of new interventions in TE and RM. It can also serve as a valuable resource and educational tool for scientists, engineers, and clinicians in the field by providing an overview of the ethical considerations relevant to their work. Impact statement To our knowledge, this is the first time that the ethical implications of Tissue Engineering (TE) have been reviewed systematically. By gathering existing scholarly work and identifying knowledge gaps, this review facilitates further research into the ethical and societal implications of TE and Regenerative Medicine (RM) and other emerging biomedical technologies. Moreover, it will serve as a valuable resource and educational tool for scientists, engineers, and clinicians in the field by providing an overview of the ethical considerations relevant to their work. As such, our review may promote successful and responsible development of new strategies in TE and RM.

Ethical challenges with 3D bioprinted tissues and organs

3D Bioprinting is fast advancing to offer capabilities to process living cells into geometrically and functionally complex tissue and organ substitutes. As bioprinted constructs are making their way into clinic, the bioprinting community needs to consider the responsible innovation and translation of the bioprinted tissues and organs.

Three-Dimensional (3D) Printing of Organs according to the Perspective of Islamic Law

The outburst of the fourth Industrial Revolution had a significant impact on many aspects of life. The discovery of new technologies in medicine has resulted in innovations: organ transplants. The introduction of three-dimensional (3D) organ printing technology promises improvements to the field. Organs such as the liver, kidneys, heart and others are printed to meet the needs of the actual organs. However, the production of prototype organs to replace the original organs is associated with the issue of changing the creation of Allah. Accordingly, this study will analyse the issue of changing the creation of God in three-dimensional (3D) organ printing technology according to the perspective of Islamic law. Several appropriate methodologies in Islamic law (usul fiqh) are used such as legal reasoning through maqasid shariah perspective and analogical reasoning. The result shows that three-dimensional (3D) organ printing technology falls under the permissible category of changing the creation of Allah because it can save human lives. The production of organs through 3D printing involving changes included in the category of necessity (daruri) and need (hajiy) is permissible, but the category of desirable (tahsini) requires further specifications.

Ethical and regulatory issues of stem cell-derived 3-dimensional organoid and tissue therapy for personalised regenerative medicine

BACKGROUND

Regenerative medicine has the potential to treat genetic disorders and replace damaged or missing tissue. The use of donor or animal tissue raises many well-known issues, including limited tissue availability, the possibility of rejection and patient infection. Stem cell therapy raised hope of overcoming these issues, but created new risks including tumour formation and limited benefit if the desired target tissue does not form. The recent development of 3-dimensional tissues, including organoids, allows the creation of more complex tissues for personalised regenerative medicine.

METHODS

This article details the potential health risks of 3-dimensional organoid and tissue therapy versus dissociated stem cell therapy. The current ethical and regulatory issues surrounding 3-dimensional organoid and tissue therapy are presented with a focus on the highly influential FDA and International Society of Stem Cell Research (ISSCR) guidelines.

CONCLUSIONS

The potential use of 3-dimensional organoid and tissue therapy may deliver greater patient benefits than other regenerative medicine approaches, but raises new health and ethical risks. Preclinical testing of these therapies will not mitigate some of their risks; they may only be understood after first-in-human trials. The potential irreversibility and high risk of these therapies affects how clinical trials should be structured, including post-trial care for participants.

A review on cell damage, viability, and functionality during 3D bioprinting

Three-dimensional (3D) bioprinting fabricates 3D functional tissues/organs by accurately depositing the bioink composed of the biological materials and living cells. Even though 3D bioprinting techniques have experienced significant advancement over the past decades, it remains challenging for 3D bioprinting to artificially fabricate functional tissues/organs with high post-printing cell viability and functionality since cells endure various types of stress during the bioprinting process. Generally, cell viability which is affected by several factors including the stress and the environmental factors, such as pH and temperature, is mainly determined by the magnitude and duration of the stress imposed on the cells with poorer cell viability under a higher stress and a longer duration condition. The maintenance of high cell viability especially for those vulnerable cells, such as stem cells which are more sensitive to multiple stresses, is a key initial step to ensure the functionality of the artificial tissues/organs. In addition, maintaining the pluripotency of the cells such as proliferation and differentiation abilities is also essential for the 3D-bioprinted tissues/organs to be similar to native tissues/organs. This review discusses various pathways triggering cell damage and the major factors affecting cell viability during different bioprinting processes, summarizes the studies on cell viabilities and functionalities in different bioprinting processes, and presents several potential approaches to protect cells from injuries to ensure high cell viability and functionality.

The translational paradigm of nanobiomaterials: Biological chemistry to modern applications

Recently nanotechnology has evolved as one of the most revolutionary technologies in the world. It has now become a multi-trillion-dollar business that covers the production of physical, chemical, and biological systems at scales ranging from atomic and molecular levels to a wide range of industrial applications, such as electronics, medicine, and cosmetics. Nanobiomaterials synthesis are promising approaches produced from various biological elements be it plants, bacteria, peptides, nucleic acids, etc. Owing to the better biocompatibility and biological approach of synthesis, they have gained immense attention in the biomedical field. Moreover, due to their scaled-down sized property, nanobiomaterials exhibit remarkable features which make them the potential candidate for different domains of tissue engineering, materials science, pharmacology, biosensors, etc. Miscellaneous characterization techniques have been utilized for the characterization of nanobiomaterials. Currently, the commercial transition of nanotechnology from the research level to the industrial level in the form of nano-scaffolds, implants, and biosensors is stimulating the whole biomedical field starting from bio-mimetic nacres to 3D printing, multiple nanofibers like silk fibers functionalizing as drug delivery systems and in cancer therapy. The contribution of single quantum dot nanoparticles in biological tagging typically in the discipline of genomics and proteomics is noteworthy. This review focuses on the diverse emerging applications of Nanobiomaterials and their mechanistic advancements owing to their physiochemical properties leading to the growth of industries on different biomedical measures. Alongside the implementation of such nanobiomaterials in several drug and gene delivery approaches, optical coding, photodynamic cancer therapy, and vapor sensing have been elaborately discussed in this review. Different parameters based on current challenges and future perspectives are also discussed here.

Within or Without You? A Perspective Comparing In Situ and Ex Situ Tissue Engineering Strategies for Articular Cartilage Repair

Human articular cartilage has a poor ability to self-repair, meaning small injuries often lead to osteoarthritis, a painful and debilitating condition which is a major contributor to the global burden of disease. Existing clinical strategies generally do not regenerate hyaline type cartilage, motivating research toward tissue engineering solutions. Prospective cartilage tissue engineering therapies can be placed into two broad categories: i) Ex situ strategies, where cartilage tissue constructs are engineered in the lab prior to implantation and ii) in situ strategies, where cells and/or a bioscaffold are delivered to the defect site to stimulate chondral repair directly. While commonalities exist between these two approaches, the core point of distinction-whether chondrogenesis primarily occurs "within" or "without" (outside) the body-can dictate many aspects of the treatment. This difference influences decisions around cell selection, the biomaterials formulation and the surgical implantation procedure, the processes of tissue integration and maturation, as well as, the prospects for regulatory clearance and clinical translation. Here, ex situ and in situ cartilage engineering strategies are compared: Highlighting their respective challenges, opportunities, and prospects on their translational pathways toward long term human cartilage repair.

Latest Advances in 3D Bioprinting of Cardiac Tissues

Cardiovascular diseases (CVDs) are known as the major cause of death worldwide. In spite of tremendous advancements in medical therapy, the gold standard for CVD treatment is still transplantation. Tissue engineering, on the other hand, has emerged as a pioneering field of study with promising results in tissue regeneration using cells, biological cues, and scaffolds. Three-dimensional (3D) bioprinting is a rapidly growing technique in tissue engineering because of its ability to create complex scaffold structures, encapsulate cells, and perform these tasks with precision. More recently, 3D bioprinting has made its debut in cardiac tissue engineering, and scientists are investigating this technique for development of new strategies for cardiac tissue regeneration. In this review, the fundamentals of cardiac tissue biology, available 3D bioprinting techniques and bioinks, and cells implemented for cardiac regeneration are briefly summarized and presented. Afterwards, the pioneering and state-of-the-art works that have utilized 3D bioprinting for cardiac tissue engineering are thoroughly reviewed. Finally, regulatory pathways and their contemporary limitations and challenges for clinical translation are discussed.

Early-Phase Clinical Trials of Bio-Artificial Organ Technology: A Systematic Review of Ethical Issues

Regenerative medicine has emerged as a novel alternative solution to organ failure which circumvents the issue of organ shortage. In preclinical research settings bio-artificial organs are being developed. It is anticipated that eventually it will be possible to launch first-in-human transplantation trials to test safety and efficacy in human recipients. In early-phase transplantation trials, however, research participants could be exposed to serious risks, such as toxicity, infections and tumorigenesis. So far, there is no ethical guidance for the safe and responsible design and conduct of early-phase clinical trials of bio-artificial organs. Therefore, research ethics review committees will need to look to related adjacent fields of research, including for example cell-based therapy, for guidance. In this systematic review, we examined the literature on early-phase clinical trials in these adjacent fields and undertook a thematic analysis of relevant ethical points to consider for early-phase clinical trials of transplantable bio-artificial organs. Six themes were identified: cell source, risk-benefit assessment, patient selection, trial design, informed consent, and oversight and accountability. Further empirical research is needed to provide insight in patient perspectives, as this may serve as valuable input in determining the conditions for ethically responsible and acceptable early clinical development of bio-artificial organs.

Application of cardiovascular 3-dimensional printing in Transcatheter aortic valve replacement

Transcatheter aortic valve replacement (TAVR) has been performed for nearly 20 years, with reliable safety and efficacy in moderate- to high-risk patients with aortic stenosis or regurgitation, with the advantage of less trauma and better prognosis than traditional open surgery. However, because surgeons have not been able to obtain a full view of the aortic root, 3-dimensional printing has been used to reconstruct the aortic root so that they could clearly and intuitively understand the specific anatomical structure. In addition, the 3D printed model has been used for the in vitro simulation of the planned procedures to predict the potential complications of TAVR, the goal being to provide guidance to reasonably plan the procedure to achieve the best outcome. Postprocedural 3D printing can be used to understand the depth, shape, and distribution of the stent. Cardiovascular 3D printing has achieved remarkable results in TAVR and has a great potential.

Progress in 3D Bioprinting Technology for Osteochondral Regeneration

Osteochondral injuries can lead to osteoarthritis (OA). OA is characterized by the progressive degradation of the cartilage tissue together with bone tissue turnover. Consequently, joint pain, inflammation, and stiffness are common, with joint immobility and dysfunction being the most severe symptoms. The increase in the age of the population, along with the increase in risk factors such as obesity, has led OA to the forefront of disabling diseases. In addition, it not only has an increasing prevalence, but is also an economic burden for health systems. Current treatments are focused on relieving pain and inflammation, but they become ineffective as the disease progresses. Therefore, new therapeutic approaches, such as tissue engineering and 3D bioprinting, have emerged. In this review, the advantages of using 3D bioprinting techniques for osteochondral regeneration are described. Furthermore, the biomaterials, cell types, and active molecules that are commonly used for these purposes are indicated. Finally, the most recent promising results for the regeneration of cartilage, bone, and/or the osteochondral unit through 3D bioprinting technologies are considered, as this could be a feasible therapeutic approach to the treatment of OA.

Role of three-dimensional printing and artificial intelligence in the management of hepatocellular carcinoma: Challenges and opportunities

Hepatocellular carcinoma (HCC) constitutes the fifth most frequent malignancy worldwide and the third most frequent cause of cancer-related deaths. Currently, treatment selection is based on the stage of the disease. Emerging fields such as three-dimensional (3D) printing, 3D bioprinting, artificial intelligence (AI), and machine learning (ML) could lead to evidence-based, individualized management of HCC. In this review, we comprehensively report the current applications of 3D printing, 3D bioprinting, and AI/ML-based models in HCC management; we outline the significant challenges to the broad use of these novel technologies in the clinical setting with the goal of identifying means to overcome them, and finally, we discuss the opportunities that arise from these applications. Notably, regarding 3D printing and bioprinting-related challenges, we elaborate on cost and cost-effectiveness, cell sourcing, cell viability, safety, accessibility, regulation, and legal and ethical concerns. Similarly, regarding AI/ML-related challenges, we elaborate on intellectual property, liability, intrinsic biases, data protection, cybersecurity, ethical challenges, and transparency. Our findings show that AI and 3D printing applications in HCC management and healthcare, in general, are steadily expanding; thus, these technologies will be integrated into the clinical setting sooner or later. Therefore, we believe that physicians need to become familiar with these technologies and prepare to engage with them constructively.

Balancing the customization and standardization: exploration and layout surrounding the regulation of the growing field of 3D-printed medical devices in China

Medical devices are instruments and other tools that act on the human body to aid clinical diagnosis and disease treatment, playing an indispensable role in modern medicine. Nowadays, the increasing demand for personalized medical devices poses a significant challenge to traditional manufacturing methods. The emerging manufacturing technology of three-dimensional (3D) printing as an alternative has shown exciting applications in the medical field and is an ideal method for manufacturing such personalized medical devices with complex structures. However, the application of this new technology has also brought new risks to medical devices, making 3D-printed devices face severe challenges due to insufficient regulation and the lack of standards to provide guidance to the industry. This review aims to summarize the current regulatory landscape and existing research on the standardization of 3D-printed medical devices in China, and provide ideas to address these challenges. We focus on the aspects concerned by the regulatory authorities in 3D-printed medical devices, highlighting the quality system of such devices, and discuss the guidelines that manufacturers should follow, as well as the current limitations and the feasible path of regulation and standardization work based on this perspective. The key points of the whole process quality control, performance evaluation methods and the concept of whole life cycle management of 3D-printed medical devices are emphasized. Furthermore, the significance of regulation and standardization is pointed out. Finally, aspects worthy of attention and future perspectives in this field are discussed.

3D Bioprinting in Skin Related Research: Recent Achievements and Application Perspectives

In recent years, significant progress has been observed in the field of skin bioprinting, which has a huge potential to revolutionize the way of treatment in injury and surgery. Furthermore, it may be considered as an appropriate platform to perform the assessment and screening of cosmetic and pharmaceutical formulations. Therefore, the objective of this paper was to review the latest advances in 3D bioprinting dedicated to skin applications. In order to explain the boundaries of this technology, the architecture and functions of the native skin were briefly described. The principles of bioprinting methods were outlined along with a detailed description of key elements that are required to fabricate the skin equivalents. Next, the overview of recent progress in 3D bioprinting studies was presented. The article also highlighted the potential applications of bioengineered skin substituents in various fields including regenerative medicine, modeling of diseases, and cosmetics/drugs testing. The advantages, limitations, and future directions of this technology were also discussed.

Cardiac Patch Transplantation Instruments for Robotic Minimally Invasive Cardiac Surgery: Initial Proof-of-concept Designs and Surgery in a Porcine Cadaver

Background: Damaged cardiac tissues could potentially be regenerated by transplanting bioengineered cardiac patches to the heart surface. To be fully paradigm-shifting, such patches may need to be transplanted using minimally invasive robotic cardiac surgery (not only traditional open surgery). Here, we present novel robotic designs, initial prototyping and a new surgical operation for instruments to transplant patches via robotic minimally invasive heart surgery.

Methods: Robotic surgical instruments and automated control systems were designed, tested with simulation software and prototyped. Surgical proof-of-concept testing was performed on a pig cadaver.

Results: Three robotic instrument designs were developed. The first (called “Claw” for the claw-like patch holder at the tip) operates on a rack and pinion mechanism. The second design (“Shell-Beak”) uses adjustable folding plates and rods with a bevel gear mechanism. The third (“HeartStamp”) utilizes a stamp platform protruding through an adjustable ring. For the HeartStamp, rods run through a cylindrical structure designed to fit a uniportal Video-Assisted Thorascopic Surgery (VATS) surgical port. Designed to work with or without a sterile sheath, the patch is pushed out by the stamp platform as it protrudes. Two instrument robotic control systems were designed, simulated in silico and one of these underwent early ‘sizing and learning’ prototyping as a proof-of-concept. To reflect real surgical conditions, surgery was run “live” and reported exactly (as-it-happened). We successfully picked up, transferred and released a patch onto the heart using the HeartStamp in a pig cadaver model.

Conclusion: These world-first designs, early prototypes and a novel surgical operation pave the way for robotic instruments for automated keyhole patch transplantation to the heart. Our novel approach is presented for others to build upon free from restrictions or cost—potentially a significant moment in myocardial regeneration surgery which may open a therapeutic avenue for patients unfit for traditional open surgery.

3D Printing in Eye Care

Three-dimensional printing enables precise modeling of anatomical structures and has been employed in a broad range of applications across medicine. Its earliest use in eye care included orbital models for training and surgical planning, which have subsequently enabled the design of custom-fit prostheses in oculoplastic surgery. It has evolved to include the production of surgical instruments, diagnostic tools, spectacles, and devices for delivery of drug and radiation therapy. During the COVID-19 pandemic, increased demand for personal protective equipment and supply chain shortages inspired many institutions to 3D-print their own eye protection. Cataract surgery, the most common procedure performed worldwide, may someday make use of custom-printed intraocular lenses. Perhaps its most alluring potential resides in the possibility of printing tissues at a cellular level to address unmet needs in the world of corneal and retinal diseases. Early models toward this end have shown promise for engineering tissues which, while not quite ready for transplantation, can serve as a useful model for in vitro disease and therapeutic research. As more institutions incorporate in-house or outsourced 3D printing for research models and clinical care, ethical and regulatory concerns will become a greater consideration. This report highlights the uses of 3D printing in eye care by subspecialty and clinical modality, with an aim to provide a useful entry point for anyone seeking to engage with the technology in their area of interest.

The promising rise of bioprinting in revolutionalizing medical science: Advances and possibilities

Bioprinting is a relatively new yet evolving technique predominantly used in regenerative medicine and tissue engineering. 3D bioprinting techniques combine the advantages of creating Extracellular Matrix (ECM)like environments for cells and computer-aided tailoring of predetermined tissue shapes and structures. The essential application of bioprinting is for the regeneration or restoration of damaged and injured tissues by producing implantable tissues and organs. The capability of bioprinting is yet to be fully scrutinized in sectors like the patient-specific spatial distribution of cells, bio-robotics, etc. In this review, currently developed experimental systems and strategies for the bioprinting of different types of tissues as well as for drug delivery and cancer research are explored for potential applications. This review also digs into the most recent opportunities and future possibilities for the efficient implementation of bioprinting to restructure medical and technological practices.

Surveillance in Next-Generation Personalized Healthcare: Science and Ethics of Data Analytics in Healthcare

Advances in science and technology have allowed for incredible improvements in healthcare. Additionally, the digital revolution in healthcare provides new ways of collecting and storing large volumes of patient data, referred to as big healthcare data. As a result, healthcare providers are now able to use data to gain a deeper understanding of how to treat an individual in what is referred to as personalized healthcare. Regardless, there are several ethical challenges associated with big healthcare data that affect how personalized healthcare is delivered. To highlight these issues, this article will review the role of big data in personalized healthcare while also discussing the ethical challenges associated with it. The article will also discuss public health surveillance, its implications, and the challenges associated with collecting participants' information. The article will proceed by highlighting next generation technologies, including robotics and 3D printing. The article will conclude by providing recommendations on how patient privacy can be protected in next-generation personalized healthcare.

In Vitro Strategies to Vascularize 3D Physiologically Relevant Models

Vascularization of 3D models represents a major challenge of tissue engineering and a key prerequisite for their clinical and industrial application. The use of prevascularized models built from dedicated materials could solve some of the actual limitations, such as suboptimal integration of the bioconstructs within the host tissue, and would provide more in vivo-like perfusable tissue and organ-specific platforms. In the last decade, the fabrication of vascularized physiologically relevant 3D constructs has been attempted by numerous tissue engineering strategies, which are classified here in microfluidic technology, 3D coculture models, namely, spheroids and organoids, and biofabrication. In this review, the recent advancements in prevascularization techniques and the increasing use of natural and synthetic materials to build physiological organ-specific models are discussed. Current drawbacks of each technology, future perspectives, and translation of vascularized tissue constructs toward clinics, pharmaceutical field, and industry are also presented. By combining complementary strategies, these models are envisioned to be successfully used for regenerative medicine and drug development in a near future.

Biofabrication Strategies for Musculoskeletal Disorders: Evolution towards Clinical Applications

Biofabrication has emerged as an attractive strategy to personalise medical care and provide new treatments for common organ damage or diseases. While it has made impactful headway in e.g., skin grafting, drug testing and cancer research purposes, its application to treat musculoskeletal tissue disorders in a clinical setting remains scarce. Albeit with several in vitro breakthroughs over the past decade, standard musculoskeletal treatments are still limited to palliative care or surgical interventions with limited long-term effects and biological functionality. To better understand this lack of translation, it is important to study connections between basic science challenges and developments with translational hurdles and evolving frameworks for this fully disruptive technology that is biofabrication. This review paper thus looks closely at the processing stage of biofabrication, specifically at the bioinks suitable for musculoskeletal tissue fabrication and their trends of usage. This includes underlying composite bioink strategies to address the shortfalls of sole biomaterials. We also review recent advances made to overcome long-standing challenges in the field of biofabrication, namely bioprinting of low-viscosity bioinks, controlled delivery of growth factors, and the fabrication of spatially graded biological and structural scaffolds to help biofabricate more clinically relevant constructs. We further explore the clinical application of biofabricated musculoskeletal structures, regulatory pathways, and challenges for clinical translation, while identifying the opportunities that currently lie closest to clinical translation. In this article, we consider the next era of biofabrication and the overarching challenges that need to be addressed to reach clinical relevance.

Modern World Applications for Nano-Bio Materials: Tissue Engineering and COVID-19

Over the past years, biomaterials-based nano cues with multi-functional characteristics have been engineered with high interest. The ease in fine tunability with maintained compliance makes an array of nano-bio materials supreme candidates for the biomedical sector of the modern world. Moreover, the multi-functional dimensions of nano-bio elements also help to maintain or even improve the patients' life quality most securely by lowering or diminishing the adverse effects of in practice therapeutic modalities. Therefore, engineering highly efficient, reliable, compatible, and recyclable biomaterials-based novel corrective cues with multipurpose applications is essential and a core demand to tackle many human health-related challenges, e.g., the current COVID-19 pandemic. Moreover, robust engineering design and properly exploited nano-bio materials deliver wide-ranging openings for experimentation in the field of interdisciplinary and multidisciplinary scientific research. In this context, herein, it is reviewed the applications and potential on tissue engineering and therapeutics of COVID-19 of several biomaterials. Following a brief introduction is a discussion of the drug delivery routes and mechanisms of biomaterials-based nano cues with suitable examples. The second half of the review focuses on the mainstream applications changing the dynamics of 21st century materials. In the end, current challenges and recommendations are given for a healthy and foreseeable future.

The path toward ectogenesis: looking beyond the technical challenges

BACKGROUND

Breakthroughs in animal studies make the topic of human application of ectogenesis for medical and non-medical purposes more relevant than ever before. While current data do not yet demonstrate a reasonable expectation of clinical benefit soon, several groups are investigating the feasibility of artificial uteri for extracorporeal human gestation.

MAIN TEXT

This paper offers the first comprehensive and up to date discussion of the most important pros and cons of human ectogenesis in light of clinical application, along with an examination of crucial ethical (and legal) issues that continued research into, and the clinical translation of, ectogenesis gives rise to. The expected benefits include advancing prenatal medicine, improving neonatal intensive care, and providing a novel pathway towards biological parenthood. This comes with important future challenges. Prior to human application, important questions have to be considered concerning translational research, experimental use of human fetuses and appropriate safety testing. Key questions are identified regarding risks to ectogenesis' subjects, and the physical impact on the pregnant person when transfer from the uterus to the artificial womb is required. Critical issues concerning proportionality have to be considered, also in terms of equity of access, relative to the envisaged application of ectogenesis. The advent of ectogenesis also comes with crucial issues surrounding abortion, extended fetal viability and moral status of the fetus.

CONCLUSIONS

The development of human ectogenesis will have numerous implications for clinical practice. Prior to human testing, close consideration should be given to whether (and how) ectogenesis can be introduced as a continuation of existing neonatal care, with due attention to both safety risks to the fetus and pressures on pregnant persons to undergo experimental and/or invasive procedures. Equally important is the societal debate about the acceptable applications of ectogenesis and how access to these usages should be prioritized. It should be anticipated that clinical availability of ectogenesis, possibly first as a way to save extremely premature fetuses, may spark demand for non-medical purposes, like avoiding physical and social burdens of pregnancy.

Three-Dimensional Engineered Peripheral Nerve: Toward a New Era of Patient-Specific Nerve Repair Solutions

Reconstruction of peripheral nerve injuries (PNIs) with substance loss remains challenging because of limited treatment solutions and unsatisfactory patient outcomes. Currently, nerve autografting is the first-line management choice for bridging critical-sized nerve defects. The procedure, however, is often complicated by donor site morbidity and paucity of nerve tissue, raising a quest for better alternatives. The application of other treatment surrogates, such as nerve guides, remains questionable, and it is inefficient in irreducible nerve gaps. More importantly, these strategies lack customization for personalized patient therapy, which is a significant drawback of these nerve repair options. This negatively impacts the fascicle-to-fascicle regeneration process, critical to restoring the physiological axonal pathway of the disrupted nerve. Recently, the use of additive manufacturing (AM) technologies has offered major advancements to the bioengineering solutions for PNI therapy. These techniques aim at reinstating the native nerve fascicle pathway using biomimetic approaches, thereby augmenting end-organ innervation. AM-based approaches, such as three-dimensional (3D) bioprinting, are capable of biofabricating 3D-engineered nerve graft scaffolds in a patient-specific manner with high precision. Moreover, realistic in vitro models of peripheral nerve tissues that represent the physiologically and functionally relevant environment of human organs could also be developed. However, the technology is still nascent and faces major translational hurdles. In this review, we spotlighted the clinical burden of PNIs and most up-to-date treatment to address nerve gaps. Next, a summarized illustration of the nerve ultrastructure that guides research solutions is discussed. This is followed by a contrast of the existing bioengineering strategies used to repair peripheral nerve discontinuities. In addition, we elaborated on the most recent advances in 3D printing and biofabrication applications in peripheral nerve modeling and engineering. Finally, the major challenges that limit the evolution of the field along with their possible solutions are also critically analyzed.

Engineering bioinks for 3D bioprinting

In recent years, three-dimensional (3D) bioprinting has attracted wide research interest in biomedical engineering and clinical applications. This technology allows for unparalleled architecture control, adaptability and repeatability that can overcome the limits of conventional biofabrication techniques. Along with the emergence of a variety of 3D bioprinting methods, bioinks have also come a long way. From their first developments to support bioprinting requirements, they are now engineered to specific injury sites requirements to mimic native tissue characteristics and to support biofunctionality. Current strategies involve the use of bioinks loaded with cells and biomolecules of interest, without altering their functions, to deliverin situthe elements required to enhance healing/regeneration. The current research and trends in bioink development for 3D bioprinting purposes is overviewed herein.

Current Insights Into 3D Bioprinting: An Advanced Approach for Eye Tissue Regeneration

Three-dimensional (3D) printing is a game changer technology that holds great promise for a wide variety of biomedical applications, including ophthalmology. Through this emerging technique, specific eye tissues can be custom-fabricated in a flexible and automated way, incorporating different cell types and biomaterials in precise anatomical 3D geometries. However, and despite the great progress and possibilities generated in recent years, there are still challenges to overcome that jeopardize its clinical application in regular practice. The main goal of this review is to provide an in-depth understanding of the current status and implementation of 3D bioprinting technology in the ophthalmology field in order to manufacture relevant tissues such as cornea, retina and conjunctiva. Special attention is paid to the description of the most commonly employed bioprinting methods, and the most relevant eye tissue engineering studies performed by 3D bioprinting technology at preclinical level. In addition, other relevant issues related to use of 3D bioprinting for ocular drug delivery, as well as both ethical and regulatory aspects, are analyzed. Through this review, we aim to raise awareness among the research community and report recent advances and future directions in order to apply this advanced therapy in the eye tissue regeneration field.