The research, published in the journal 3D Printing in Medicine, was conducted by a team from the Regional Hospital in Liberec, the Motol Faculty Hospital in Prague, the Faculty of Medicine in Hradec Kralove and the Technical University of Liberec in the Czech Republic. Led by Lukas Capek of the Department of Clinical Biomechanics, the group set out to answer a deceptively simple question: how well do the materials commonly fed into desktop fused deposition modeling printers actually mimic the mechanical behavior of pediatric cranial bone? The answer, distilled through mechanical testing and computer simulation, is that most of them do not, and that even the best candidate carries trade-offs that anyone building surgical training models needs to understand.

The team compared six widely available fused deposition modeling materials: polylactic acid, better known as PLA; acrylonitrile styrene acrylate, or ASA; PET-G; a commercial filament marketed under the name Simu Bone specifically for anatomical models; polypropylene, or PP; and thermoplastic polyurethane, or TPU. These were benchmarked against genuine ex vivo specimens of pediatric calvarial bone, the skull cap bone harvested with ethical approval from Motol University Hospital. The mechanical yardstick was the three-point bending test, a standard technique in which a sample is supported at both ends and loaded in the middle until it deflects, allowing researchers to extract the Young’s modulus, a measure of stiffness that describes how much a material resists elastic deformation.

The numbers revealed a striking spread. Native pediatric cranial bone exhibited a mean Young’s modulus of 375 plus or minus 204 megapascals, a value that reflects both the intrinsic softness of infant skull bone and considerable biological variability between specimens. Simu Bone, the filament explicitly designed to imitate bone, turned out to be dramatically too stiff, measuring 3380 plus or minus 14 megapascals, roughly nine times stiffer than the real tissue it is meant to emulate. At the opposite extreme, TPU was far too compliant at just 61 plus or minus 11 megapascals, behaving more like a flexible rubber than a cranial plate. Polypropylene emerged as the closest match to native bone mechanics, although the researchers note that printing with it posed practical challenges, since PP is notoriously prone to warping and poor bed adhesion on consumer printers.

Between those extremes sat the everyday workhorse filaments. PLA, ASA and PET-G, the materials most hobbyists and hospital makerspaces reach for first, all landed well above the stiffness of pediatric calvarial bone, meaning models printed from them will feel rigid and unyielding where a real infant skull would flex and give under surgical instruments. That discrepancy matters more than it might appear. In craniosynostosis procedures, surgeons rely on tactile feedback, feeling how bone bends, springs and fractures as it is cut, contoured and reshaped. A model that is nine times too stiff invites the trainee to apply far more force than would ever be safe in the operating room, while one that is too soft fails to convey the resistance that guides instrument handling.

The researchers also explored a popular workaround: tuning the infill density of the print. Fused deposition modeling builds parts as hollow shells filled with internal lattice patterns, and reducing the infill percentage is the easiest way to soften a printed part without changing material. The experiments showed that infill reduction does modestly decrease stiffness, offering a degree of tunability. But the effect is limited and gradual, and it cannot bridge the enormous gap between, say, a 3380 megapascal filament and 375 megapascal bone. Infill tuning, in other words, is a fine adjustment tool, not a substitute for choosing the right polymer in the first place.

Perhaps the most conceptually important finding came from the finite element analysis, the computational half of the study. The team built numerical simulations of the bending tests to explore whether matching a single global property such as overall elasticity is enough to make a printed model behave like bone. The simulations indicated that it is not. Regional deformation patterns, the way strain distributes across the geometry of a skull segment during loading, are critical for realistic simulation, and a material can match the average stiffness of bone while still deforming in the wrong places and in the wrong way. This finding pushes the field beyond the naive goal of hitting one target number and toward the harder challenge of replicating the spatial mechanical behavior of layered, heterogeneous cranial bone.

The implications reach well beyond the laboratory. Patient-specific three-dimensional printed models have become a mainstay of preoperative planning and surgical rehearsal for complex craniofacial cases, and they are increasingly central to training the next generation of neurosurgeons and craniofacial surgeons. Hospitals around the world have installed banks of desktop printers precisely because printed skulls are cheap, fast to produce and anatomically faithful, derived directly from patient imaging. This study adds a crucial caveat to that enthusiasm: anatomical accuracy without mechanical fidelity produces a model that looks right but feels wrong, and in surgery, feel is often what counts. The authors emphasize that anyone selecting materials for cranial training models must balance mechanical fidelity against printability, since the most mechanically faithful option, polypropylene, is also among the most difficult to print reliably.

There are also broader lessons for the growing field of medical simulation. The wide scatter in the native bone measurements, with a standard deviation of more than half the mean modulus, is a reminder that pediatric cranial bone is not a single well-defined material but a biological structure whose properties vary with donor age, skull location and the layered architecture of inner and outer cortical tables separated by diploë. Any single polymer, however well tuned, will be an approximation. The Czech team’s work, supported by the Ministry of Health of the Czech Republic under grant NW25-08-00228, provides the quantitative baseline that material scientists and biomedical engineers will need as they develop next-generation bone-mimicking filaments, and it gives surgical educators an evidence-based ranking for the materials they can buy today. For now, the practical takeaway is clear: if the goal is to rehearse surgery on an infant skull, polypropylene is the closest thing to bone that a standard fused deposition modeling printer can deliver, provided the printer operator is prepared to wrestle with its temperamental printing behavior.

Subject of Research: Comparative mechanical assessment of 3D printed skull materials versus pediatric cranial bone for craniosynostosis surgical training

Article Title: Comparative assessment of 3D printed skull materials and ex vivo bone for craniosynostosis training: a finite element analysis

Article References: Capek, L., Celisova, S., Taborsky, J., Vitvar, J., Benes, V., & Solfronk, P. (2026). Comparative assessment of 3D printed skull materials and ex vivo bone for craniosynostosis training: a finite element analysis. 3D Printing in Medicine. https://doi.org/10.1186/s41205-026-00347-5

Image Credits: AI Generated

DOI: 10.1186/s41205-026-00347-5

Keywords: craniosynostosis, 3D printing, fused deposition modeling, surgical training, finite element analysis, Young's modulus, pediatric cranial bone, polypropylene, Simu Bone, three-point bending, patient-specific models, surgical simulation

The study focuses on the maturation process of parietal cells—crucial components of gastric epithelium involved in acid secretion. By leveraging the capabilities of assembloids, the researchers successfully created a model that encapsulates different regions of the stomach, allowing for a more accurate representation of its diverse cellular environment. This multi-regional approach is essential as it reflects the varying physiological characteristics across distinct sections of the gastric tract, thereby providing insights that single-region models simply cannot offer.

Antral foveolar hyperplasia, a condition associated with gastric inflammation and potential precursors to more serious ailments, has long puzzled researchers and clinicians. The unique insights gained from the assembloid model enable a deeper understanding of the cellular dynamics and stress responses that characterize this condition. By utilizing patient-derived cells to populate these assembloids, the research team has taken a significant step toward personalized medicine, wherein treatments can be tailored to individual cellular responses and vulnerabilities.

One of the most remarkable aspects of this study is the ability of these assembloids to replicate not just the structural properties of gastric tissue but also its functional behaviors. This includes the secretion of gastric acids and hormones, critical for digestion, and maintaining metabolic homeostasis. The researchers meticulously monitored the activity of key signaling pathways to determine how they differ in health versus disease states, providing a treasure trove of data for future studies aimed at developing interventions for gastric disorders.

The implications of this research extend beyond the immediate understanding of gastric physiology. As the assembloid technology matures, it can potentially be harnessed for drug testing and toxicity assessments. With the capacity to model disease states accurately, these assemblies could serve as platforms for screening new pharmacological agents, thus streamlining the drug development pipeline and ensuring that only the most promising candidates make it to clinical trials.

As gastritis, antral foveolar hyperplasia, and other related conditions continue to pose significant health burdens worldwide, the urgency for novel therapeutic strategies has never been greater. The ability to generate patient-specific assembloids empowers clinicians and researchers with tools that facilitate the identification of unique biomarkers and therapeutic targets in individual patients. This could drastically improve patient outcomes by allowing for treatments that are more aligned with the underlying biological realities of the disease.

Furthermore, multi-regional assembloids present an unprecedented opportunity for educational and training purposes in the biomedical field. They can serve as state-of-the-art models for instructing students and new researchers about the complexities of human gastronomy, disease pathology, and cellular interactions in a controlled, replicable environment. With the potential to observe real-time cellular processes and responses to various stimuli, these assembloids redefine traditional approaches to both teaching and learning in the life sciences.

While the excitement surrounding this research is palpable, it is essential to consider the ethical dimensions of using human cells in such advanced bioengineering applications. Ensuring that all procedures align with ethical standards and regulations is paramount as the field progresses. The research team is committed to maintaining the highest ethical standards and transparency in all aspects of their research, from cell sourcing to potential clinical applications.

The potential of multi-regional assembloids extends to collaborations across disciplines, fostering partnerships between bioengineers, clinicians, and molecular biologists. This interdisciplinary approach is crucial for addressing the multifaceted challenges posed by gastric diseases and could result in innovations that further enhance our understanding of human health and disease. The collaborative endeavors stemming from this research could pave the way for comprehensive strategies that tackle gastric inflammation at multiple levels.

In summary, the study on human gastric multi-regional assembloids represents a watershed moment in biomedical engineering and clinical research. The promising results signal a shift toward integrating advanced model systems in understanding, diagnosing, and treating gastric disorders. With these developments, researchers are poised to unveil new therapeutic strategies that are personalized and effective, offering hope for patients afflicted by gastric diseases.

Through the lens of this research, the integration of technology, biology, and patient care exemplifies the future of medicine—one that is not only innovative but also deeply empathetic toward individual patient needs. As this work gains traction in the scientific community, its influence on both basic and applied sciences is likely to resonate for years to come, making it a cornerstone of future research in the field of gastroenterology.

As we stand on the precipice of this new frontier in gastric research, it is clear that the journey has only just begun. The possibilities are vast and exciting, and as the research community continues to harness the capabilities of these advanced assembloids, one can only imagine the groundbreaking discoveries awaiting us in the coming years.

Subject of Research: Human gastric multi-regional assembloids for functional parietal maturation and patient-specific modelling of antral foveolar hyperplasia.

Article Title: Human gastric multi-regional assembloids for functional parietal maturation and patient-specific modelling of antral foveolar hyperplasia.

Article References:
Jones, B.C., Benedetti, G., Calà, G. et al. Human gastric multi-regional assembloids for functional parietal maturation and patient-specific modelling of antral foveolar hyperplasia. Nat. Biomed. Eng (2026). https://doi.org/10.1038/s41551-025-01553-y

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41551-025-01553-y

Keywords: gastric multi-regional assembloids, parietal cell maturation, antral foveolar hyperplasia, personalized medicine, bioengineering, gastric health, drug testing, ethical standards, interdisciplinary collaboration.