A Review of Recent Advances in 3D Bioprinting With an Eye on Future Regenerative Therapies in Veterinary Medicine

Alginate-Dialdehyde-Based Reporter Ink Enabling Online Detection of Matrix Metalloproteinase Activity of Encapsulated Cells

Biofabrication and three-dimensional (3D) bioprinting enable precise spatial arrangement of cells within biomaterial scaffolds. We developed an alginate-based and Förster resonance energy transfer (FRET)-responsive "turn-on" reporter ink platform to enable real-time monitoring of matrix metalloproteinase (MMP) activity. Three distinct MMP-cleavable turn-on peptide reporters were synthesized and characterized for their cell-specific cleavage profiles using recombinant MMPs, cell-derived media, and different cell cultures (NIH3T3, HEK293, and MelHo). All turn-on reporters were covalently and site-specifically incorporated into alginate dialdehyde (ADA) to yield an MMP reporter ink. The ADA reporter ink with an MMP 13 turn-on reporter was responsive to all tested cell types over time within the cast bulk constructs. The ADA reporter ink material blended with gelatin had comparable print resolution and structural fidelity as observed for ADA. The extrusion-based bioprinted MelHo cell grids, measuring 2 × 2 cm2 and containing 1 × 106 cells/mL, exhibited MMP activity responses comparable to those of the casted reporter ink system, with a 3-fold increase observed at 24 h. This study introduces a versatile, FRET-based alginate bioink platform for the real-time monitoring of MMP activities, expanding the toolkit to understand cellular performance in bioprinted 3D constructs.

Risk of Permanent Corneal Injury in Microgravity: Spaceflight-Associated Hazards, Challenges to Vision Restoration, and Role of Biotechnology in Long-Term Planetary Missions

Human space exploration presents an unparalleled opportunity to study life in extreme environments-but it also exposes astronauts to physiological stressors that jeopardize key systems like vision. Corneal health, essential for maintaining precise visual acuity, is threatened by microgravity-induced fluid shifts, cosmic radiation, and the confined nature of spacecraft living environments. These conditions elevate the risk of corneal abrasions, infections, and structural damage. In addition, Spaceflight-Associated Neuro-Ocular Syndrome (SANS)-while primarily affecting the posterior segment-has also been potentially linked to anterior segment alterations such as corneal edema and tear film instability. This review examines these ocular challenges and assesses current mitigation strategies. Traditional approaches, such as terrestrial eye banking and corneal transplantation, are impractical for spaceflight due to the limited viability of preserved tissues, surgical complexities, anesthetic risks, infection potential, and logistical constraints. The paper explores emerging technologies like 3D bioprinting and stem cell-based tissue engineering, which offer promising solutions by enabling the on-demand production of personalized corneal constructs. Complementary advancements, including adaptive protective eyewear, bioengineered tear substitutes, telemedicine, and AI-driven diagnostic tools, also show potential in autonomously managing ocular health during long-duration missions. By addressing the complex interplay of environmental stressors and biological vulnerabilities, these innovations not only safeguard astronaut vision and mission performance but also catalyze new pathways for regenerative medicine on Earth. The evolution of space-based ophthalmic care underscores the dual impact of space medicine investments across planetary exploration and terrestrial health systems.

3D bioprinting technology innovation in female reproductive system

Several diseases affect the female reproductive system, and both disease factors and treatments impact its integrity and function. Consequently, understanding the mechanisms of disease occurrence and exploring treatment methods are key research focuses in obstetrics and gynecology. However, constructing accurate disease models requires a microenvironment closely resembling the human body, and current animal models and 2D in vitro cell models fall short in this regard. Thus, innovative in vitro female reproductive system models are urgently needed. Additionally, female reproductive system diseases often cause tissue loss, yet effective tissue repair and regeneration have long been a bottleneck in the medical field. 3D bioprinting offers a solution by enabling the construction of implants with tissue repair and regeneration capabilities, promoting cell adhesion, extension, and proliferation. This helps maintain the long-term efficacy of bioactive implants and achieves both structural and functional repair of the reproductive system. By combining live cells with biomaterials, 3D bioprinting can create in vitro 3D biomimetic cellular models, facilitating in-depth studies of cell-cell and cell-extracellular microenvironment interactions, which enhances our understanding of reproductive system diseases and supports disease-specific drug screening. This article reviews 3D bioprinting methods and materials applicable to the female reproductive system, discussing their advantages and limitations to aid in selecting optimal 3D bioprinting strategies. We also summarize and critically evaluate recent advancements in 3D bioprinting applications for tissue regeneration and in vitro disease models and address the prospects and challenges for translating 3D bioprinting technology into clinical applications within the female reproductive system.

Application of 3D printing in veterinarian science

This article explores the transformative impact of 3D printing technology in veterinary medicine. It focuses on applications in various areas such as prosthetics and surgical planning. 3D printing allows for the creation of customized solutions for each animal, thus improving treatment outcomes and reducing surgical risks. Case studies demonstrate the successful adoption of this technology. It highlights innovations that improve patient care and improve veterinary practice. The discussion highlights the future potential of 3D printing in the advancement of veterinary medicine. It also considers ethical and practical challenges.

Application of Additive Manufacturing in Assisted Reproductive Techniques: What Is the Evidence? A Clinical and Technical Systematic Review of the Literature

Background and Objectives: This article investigates the transformative impact of 3D and bio 3D printing technologies in assisted reproductive technology (ART), offering a comprehensive review of their applications in improving reproductive outcomes. Materials and Methods: Following PRISMA guidelines, we conducted a thorough literature search focusing on the intersection of ART and additive manufacturing, resulting in the inclusion of 48 research papers. Results: The study highlights bio 3D printing's potential in revolutionizing female infertility treatments, especially in follicle complex culture and ovary printing. We explore the use of decellularized extracellular matrix (dECM) as bioink, demonstrating its efficacy in replicating the ovarian microenvironment for in vitro maturation of primordial oocytes. Furthermore, advancements in endometrial cavity interventions are discussed, including the application of sustained-release systems for growth factors and stem cell integration for endometrial regeneration, showing promise in addressing conditions like Asherman's syndrome and thin endometrium. We also examine the role of conventional 3D printing in reproductive medicine, including its use in educational simulators, personalized IVF instruments, and microfluidic platforms, enhancing training and precision in reproductive procedures. Conclusions: Our review underscores both 3D printing technologies' contribution to the dynamic landscape of reproductive medicine. They offer innovative solutions for individualized patient care, augmenting success rates in fertility treatments. This research not only presents current achievements but also anticipates future advancements in these domains, promising to expand the horizons for individuals and families seeking assistance in their reproductive journeys.

A 3D Bioprinting Approach to Studying Retinal Müller Cells

Background/Objectives: Bioprinting is an innovative technology in tissue engineering, enabling the creation of complex biological structures. This study aims to develop a three-dimensional (3D) bioprinted model of Müller cells (MCs) to enhance our understanding of their physiological and pathological roles in the retina. Methods: We investigated two different hydrogels for their ability to support the viability and differentiation of rMC-1 cells, an immortalized retinal cell line. Using 3D bioprinting technology, we assessed cell viability, differentiation, and functional characteristics through various assays, including live/dead assays and western blot analysis. Results: The collagen-based hydrogel significantly improved the viability of rMC-1 cells and facilitated the formation of spheroid aggregates, more accurately mimicking in vivo conditions compared to traditional two-dimensional (2D) culture systems. Moreover, 3D bioprinted MCs exhibited reduced markers of gliosis and oxidative stress compared to 2D cultures. Molecular analysis revealed decreased expression of GFAP and phosphorylated ERK in the 3D setting, indicating a less stressed cellular phenotype. Conclusions: Our findings demonstrate that 3D bioprinting technologies provide a more predictive platform for studying the biology of retinal MCs, which can help in the development of targeted therapeutic strategies for retinal diseases.

Innovative Bioscaffolds in Stem Cell and Regenerative Therapies for Corneal Pathologies

Corneal diseases, which can result in substantial visual impairment and loss of vision, are an important worldwide health issue. The aim of this review was to investigate the novel application of bioscaffolds in stem cell and regenerative treatments for the treatment of corneal disorders. The current literature reports that organic and artificial substances create bioscaffolds that imitate the inherent structure of the cornea, facilitating the attachment, growth, and specialization of stem cells. Sophisticated methods such as electrospinning, 3D bioprinting, and surface modification have been reported to enhance the characteristics of the scaffold. These bioscaffolds have been shown to greatly improve the survival of stem cells and facilitate the regrowth of corneal tissue in both laboratory and live animal experiments. In addition, the incorporation of growth factors and bioactive compounds within the scaffolds can promote a favorable milieu for corneal regeneration. To summarize, the advancement of these groundbreaking bioscaffolds presents a hopeful treatment strategy for the regeneration of the cornea, which has the potential to enhance the results for individuals suffering from corneal disorders. This study highlights the possibility of utilizing the fields of biomaterials science and stem cell treatment to tackle medical demands that have not yet been satisfied in the field of ophthalmology.

Enhancing periodontal defences with nanofiber treatment: recent advances and future prospects

The term periodontal disease is used to define diseases characterised by inflammation and regeneration of the gums, cementum, supporting bone, and periodontal ligament. The conventional treatment involves the combination of scaling, root planning, and surgical approaches which are invasive and can pose certain challenges. Intrapocket administration of nanofibers can be used for overcoming challenges which can help in speeding up the wound repair process and can also be used to promote osteogenesis. To help make drug delivery more effective, nanofibers are an interesting solution. Nanofibers are nanosized 3D structures that can fill the pockets and have excellent mucoadhesion which prolongs their retention time on the target site. Moreover, their structure mimics the natural extracellular matrix which enables nanomaterials to sense local biological conditions and start cellular-level reprogramming to produce the necessary therapeutic efficacy. In this review, the significance of intrapocket administration of nanofibers using recent research for the management of periodontitis has been discussed in detail. Furthermore, we have discussed polymers used for the preparation of nanofibers, nanofiber production methods, and the patents associated with these developments. This comprehensive compilation of data serves as a valuable resource, consolidating recent developments in nanofiber applications for periodontitis management into one accessible platform.

Advancing cardiac regeneration through 3D bioprinting: methods, applications, and future directions

Cardiovascular diseases (CVDs) represent a paramount global mortality concern, and their prevalence is on a relentless ascent. Despite the effectiveness of contemporary medical interventions in mitigating CVD-related fatality rates and complications, their efficacy remains curtailed by an array of limitations. These include the suboptimal efficiency of direct cell injection and an inherent disequilibrium between the demand and availability of heart transplantations. Consequently, the imperative to formulate innovative strategies for cardiac regeneration therapy becomes unmistakable. Within this context, 3D bioprinting technology emerges as a vanguard contender, occupying a pivotal niche in the realm of tissue engineering and regenerative medicine. This state-of-the-art methodology holds the potential to fabricate intricate heart tissues endowed with multifaceted structures and functionalities, thereby engendering substantial promise. By harnessing the prowess of 3D bioprinting, it becomes plausible to synthesize functional cardiac architectures seamlessly enmeshed with the host tissue, affording a viable avenue for the restitution of infarcted domains and, by extension, mitigating the onerous yoke of CVDs. In this review, we encapsulate the myriad applications of 3D bioprinting technology in the domain of heart tissue regeneration. Furthermore, we usher in the latest advancements in printing methodologies and bioinks, culminating in an exploration of the extant challenges and the vista of possibilities inherent to a diverse array of approaches.

Beyond the limiting gap length: peripheral nerve regeneration through implantable nerve guidance conduits

Peripheral nerve damage results in the loss of sensorimotor and autonomic functions, which is a significant burden to patients. Furthermore, nerve injuries greater than the limiting gap length require surgical repair. Although autografts are the preferred clinical choice, their usage is impeded by their limited availability, dimensional mismatch, and the sacrifice of another functional donor nerve. Accordingly, nerve guidance conduits, which are tubular scaffolds engineered to provide a biomimetic environment for nerve regeneration, have emerged as alternatives to autografts. Consequently, a few nerve guidance conduits have received clinical approval for the repair of short-mid nerve gaps but failed to regenerate limiting gap damage, which represents the bottleneck of this technology. Thus, it is still necessary to optimize the morphology and constituent materials of conduits. This review summarizes the recent advances in nerve conduit technology. Several manufacturing techniques and conduit designs are discussed, with emphasis on the structural improvement of simple hollow tubes, additive manufacturing techniques, and decellularized grafts. The main objective of this review is to provide a critical overview of nerve guidance conduit technology to support regeneration in long nerve defects, promote future developments, and speed up its clinical translation as a reliable alternative to autografts.

Competing interests at the heart of equine sports medicine ethics: A scoping review and thematic analysis

BACKGROUND

The ethics of using horses in sport is receiving increasing attention and media scrutiny. Sports medicine ethics is an important and well-established discipline within human medicine and biomedical ethics, which has, thus far, received little application to the equine veterinary field.

OBJECTIVES

The purpose of this scoping review was to explore the existing literature on equine sports medicine ethics, to understand the current concerns and issues, and to map areas for future research.

STUDY DESIGN

Scoping review.

METHODS

Academic databases (PubMed, Web of Science, CAB abstracts) were searched to identify papers, published in English, between 2000 and 2022, that mentioned aspect(s) of the ethics of veterinary provision to the performance horse. Additionally, grey (including lay) literature was identified through global search engines to locate supplementary and opinion articles. Relevant data on article characteristics and ethical concerns were extracted and charted. Thematic analysis was employed to identify key issues.

RESULTS

A literature source of 41 papers/articles was used; of which 35 were from veterinary sources, mostly veterinary journals and conference proceedings. Several themes were identified including: competing stakeholder interests; governing bodies, rules and regulations; provision of optimal veterinary care; confidentiality; and social licence for the veterinary profession. The most commonly mentioned specific ethical concern was the use of medication in performance horses.

MAIN LIMITATIONS

In this scoping review, we have not sought to critically analyse the ethical arguments within the included literature, but rather to collate them so that an overview of ethical concerns can be established.

CONCLUSIONS

Further consideration is required as to how the veterinary profession and sporting governing bodies can support individual veterinary surgeons to strive for the highest levels of professional conduct in equine sports medicine. The veterinary profession should continue to work towards establishing processes for determining what veterinary practices are ethical, optimal, excessive, permissible and impermissible.

Overview of Equine Stem Cells: Sources, Practices, and Potential Safety Concerns

Over the past 2 decades, equine veterinarians are turning increasingly to stem cell therapies to repair damaged tissues or to promote healing through modulation of the immune system. Research is ongoing into optimizing practices associated with stem cell product transport, dosage, and administration. Culture-expanded equine mesenchymal stem cell therapies seem safe, even when used allogeneically, but various safety concerns should be considered. Stem cells and cellular reprogramming tools hold great promise for future equine therapies.

3D printed cannulas for use in laparoscopic surgery in feline patients: A cadaveric study and case series

OBJECTIVE

To evaluate custom 3D printed laparoscopic cannulas (3DPC) in a feline cadaveric abdominal surgery model and report their use in two live feline subjects.

STUDY DESIGN

Experimental cadaver study, live subject case series.

ANIMALS

Ten feline cadavers; two feline subjects.

METHODS

Custom 3DPCs were initially modeled in a PLA filament material and then created in an autoclavable dental resin for use in live patients. The surgery time, number of surgical collisions and cannula complications were recorded during cadaver procedures before and after use of 3DPCs. Cannula complications were recorded during live procedures and patients were followed to suture removal to record any incisional complications.

RESULTS

There was a significant reduction in mean surgical time (125.6 vs. 95.2 min, p = 0.03), mean number of instrument collisions (6.8 vs. 2.6, p = 0.03), and mean number of cannula complications (10 vs. 2.2, p = 0.03) with the use of only 3DPCs during the procedure. During the live procedures the use of the 3DPCs was successful and no postoperative complications occurred at the incision sites.

CONCLUSION

The use of customized 3DPCs may improve surgical dexterity and decrease complications in advanced procedures and was not associated with any clinical complications in two cats. The use of 3DPCs in veterinary medicine may allow for wider practice of laparoscopic techniques in small animals.

Induced pluripotent stem cells in companion animals: how can we move the field forward?

Following a one medicine approach, the development of regenerative therapies for human patients leads to innovative treatments for animals, while pre-clinical studies on animals provide knowledge to advance human medicine. Among many different biological products under investigation, stem cells are among the most prominent. Mesenchymal stromal cells (MSCs) are extensively investigated, but they present challenges such as senescence and limited differentiation ability. Embryonic stem cells (ESCs) are pluripotent cells with a virtually unlimited capacity for self-renewal and differentiation, but the use of embryos carries ethical concerns. Induced pluripotent stem cells (iPSCs) can overcome all of these limitations, as they closely resemble ESCs but are derived from adult cells by reprogramming in the laboratory using pluripotency-associated transcription factors. iPSCs hold great potential for applications in therapy, disease modeling, drug screening, and even species preservation strategies. However, iPSC technology is less developed in veterinary species compared to human. This review attempts to address the specific challenges associated with generating and applying iPSCs from companion animals. Firstly, we discuss strategies for the preparation of iPSCs in veterinary species and secondly, we address the potential for different applications of iPSCs in companion animals. Our aim is to provide an overview on the state of the art of iPSCs in companion animals, focusing on equine, canine, and feline species, as well as to identify which aspects need further optimization and, where possible, to provide guidance on future advancements. Following a "step-by-step" approach, we cover the generation of iPSCs in companion animals from the selection of somatic cells and the reprogramming strategies, to the expansion and characterization of iPSCs. Subsequently, we revise the current applications of iPSCs in companion animals, identify the main hurdles, and propose future paths to move the field forward. Transferring the knowledge gained from human iPSCs can increase our understanding in the biology of pluripotent cells in animals, but it is critical to further investigate the differences among species to develop specific approaches for animal iPSCs. This is key for significantly advancing iPSC application in veterinary medicine, which at the same time will also allow gaining pre-clinical knowledge transferable to human medicine.

Space habitats for bioengineering and surgical repair: addressing the requirement for reconstructive and research tissues during deep-space missions

Numerous technical scenarios have been developed to facilitate a human return to the Moon, and as a testbed for a subsequent mission to Mars. Crews appointed with constructing and establishing planetary bases will require a superior level of physical ability to cope with the operational demands. However, the challenging environments of nearby planets (e.g. geological, atmospheric, gravitational conditions) as well as the lengthy journeys through microgravity, will lead to progressive tissue degradation and an increased susceptibility to injury. The isolation, distance and inability to evacuate in an emergency will require autonomous medical support, as well as a range of facilities and specialised equipment to repair tissue damage on-site. Here, we discuss the design requirements of such a facility, in the form of a habitat that would concomitantly allow tissue substitute production, maintenance and surgical implantation, with an emphasis on connective tissues. The requirements for the individual modules and their operation are identified. Several concepts are assessed, including the presence of adjacent wet lab and medical modules supporting the gradual implementation of regenerative biomaterials and acellular tissue substitutes, leading to eventual tissue grafts and, in subsequent decades, potential tissues/organ-like structures. The latter, currently in early phases of development, are assessed particularly for researching the effects of extreme conditions on representative analogues for astronaut health support. Technical solutions are discussed for bioengineering in an isolated planetary environment with hypogravity, from fluid-gel bath suspended manufacture to cryostorage, cell sourcing and on-site resource utilisation for laboratory infrastructure. Surgical considerations are also discussed.

Emerging biomaterials and technologies to control stem cell fate and patterning in engineered 3D tissues and organoids

The ability to create complex three-dimensional cellular models that can effectively replicate the structure and function of human organs and tissues in vitro has the potential to revolutionize medicine. Such models could facilitate the interrogation of developmental and disease processes underpinning fundamental discovery science, vastly accelerate drug development and screening, or even be used to create tissues for implantation into the body. Realization of this potential, however, requires the recreation of complex biochemical, biophysical, and cellular patterns of 3D tissues and remains a key challenge in the field. Recent advances are being driven by improved knowledge of tissue morphogenesis and architecture and technological developments in bioengineering and materials science that can create the multidimensional and dynamic systems required to produce complex tissue microenvironments. In this article, we discuss challenges for in vitro models of tissues and organs and summarize the current state-of-the art in biomaterials and bioengineered systems that aim to address these challenges. This includes both top-down technologies, such as 3D photopatterning, magnetism, acoustic forces, and cell origami, as well as bottom-up patterning using 3D bioprinting, microfluidics, cell sheet technology, or composite scaffolds. We illustrate the varying ways that these can be applied to suit the needs of different tissues and applications by focussing on specific examples of patterning the bone-tendon interface, kidney organoids, and brain cancer models. Finally, we discuss the challenges and future prospects in applying materials science and bioengineering to develop high-quality 3D tissue structures for in vitro studies.

Transcending Dimensions in Apicomplexan Research: from Two-Dimensional to Three-Dimensional In Vitro Cultures

Parasites belonging to the Apicomplexa phylum are among the most successful pathogens known in nature. They can infect a wide range of hosts, often remain undetected by the immune system, and cause acute and chronic illness. In this phylum, we can find parasites of human and veterinary health relevance, such as Toxoplasma, Plasmodium, Cryptosporidium, and Eimeria. There are still many unknowns about the biology of these pathogens due to the ethical and practical issues of performing research in their natural hosts. Animal models are often difficult or nonexistent, and as a result, there are apicomplexan life cycle stages that have not been studied. One recent alternative has been the use of three-dimensional (3D) systems such as organoids, 3D scaffolds with different matrices, microfluidic devices, organs-on-a-chip, and other tissue culture models. These 3D systems have facilitated and expanded the research of apicomplexans, allowing us to explore life stages that were previously out of reach and experimental procedures that were practically impossible to perform in animal models. Human- and animal-derived 3D systems can be obtained from different organs, allowing us to model host-pathogen interactions for diagnostic methods and vaccine development, drug testing, exploratory biology, and other applications. In this review, we summarize the most recent advances in the use of 3D systems applied to apicomplexans. We show the wide array of strategies that have been successfully used so far and apply them to explore other organisms that have been less studied.

Advancements in Three Dimensional In-Vitro Cell Culture Models

The scientific field is observing a gradual shift from monolayer cultures to three-dimensional (3D) models, as they give a more relevant data in pre-clinical stages. This review summarizes the major techniques and materials used to develop 3D platforms, especially for cancer. It also discusses the challenges and some unresolved issues of the field and highlights some techniques that have made it to the market.

3D bioprinting of tissue units with mesenchymal stem cells, retaining their proliferative and differentiating potential, in polyphosphate-containing bio-ink

The three-dimensional (3D)-printing processes reach increasing recognition as important fabrication techniques to meet the growing demands in tissue engineering. However, it is imperative to fabricate 3D tissue units, which contain cells that have the property to be regeneratively active. In most bio-inks, a metabolic energy-providing component is missing. Here a formulation of a bio-ink is described, which is enriched with polyphosphate (polyP), a metabolic energy providing physiological polymer. The bio-ink composed of a scaffold (N,O-carboxymethyl chitosan), a hydrogel (alginate) and a cell adhesion matrix (gelatin) as well as polyP substantially increases the viability and the migration propensity of mesenchymal stem cells (MSC). In addition, this ink stimulates not only the growth but also the differentiation of MSC to mineral depositing osteoblasts. Furthermore, the growth/aggregate pattern of MSC changes from isolated cells to globular spheres, if embedded in the polyP bio-ink. The morphogenetic activity of the MSC exposed to polyP in the bio-ink is corroborated by qRT-PCR data, which show a strong induction of the steady-state-expression of alkaline phosphatase, connected with a distinct increase in the expression ratio between RUNX2 and Sox2. We propose that polyP should become an essential component in bio-inks for the printing of cells that retain their regenerative activity.

Applications of 3-dimensional printing in small-animal surgery: A review of current practices

Three-dimensional (3D) printing, also called rapid prototyping or additive manufacturing, transforms digital images into 3D printed objects, typically by layering consecutive thin films of material. This technology has become increasingly accessible to the public, prompting applications in veterinary surgery. Three-dimensional prints provide direct visualization of complex 3D structures and also haptic feedback relevant to surgery. The main objective of this review is to report current applications of 3D printing in small-animal surgery, including surgical education, preoperative planning, and treatment of tissue defects. The reported uses of 3D prints, their proposed advantages, and current limitations are discussed considering published evidence. Aspects of the manufacturing process specific to each application are described, along with current practices in veterinary surgery.