The increase in the prevalence of liver diseases and the lack of versatile treatment options for end-stage liver diseases stresses the need for novel approaches and advanced technologies for developing physiologically and pathologically relevant models of the liver. Liver bioengineering through bioprinting has emerged as a pivotal area of research, aiming to address the critical shortage of donor organs, improve drug testing, and improve disease modeling. Through bioprinting the complex structure, composition and geometry of the liver microstructure can be replicated to give rise to liver models that can mimic the healthy or diseased tissue. These capabilities render bioprinted liver models suitable for advancing drug discovery and testing studies, as well as disease modeling. This review paper explores the application of bioprinting technologies in liver tissue engineering, highlighting the progress in the field through exploring materials, cell sources, and new current techniques used in the bioprinting of liver models. Additionally, the article explores spheroid printing and current preclinical models as well as key challenges and future perspectives. This comprehensive overview aims to provide insights into the current state of liver bioengineering through bioprinting and to identify future directions for research and clinical application.

With the rising global incidence of cancer and the limitations of traditional treatment methods, the integration of three-dimensional (3D) printing technology with drug delivery systems offers a promising solution for precision medicine. 3D printing, with its high flexibility and precise production control, allows for the accurate modulation of drug delivery systems, particularly in terms of targeted delivery and controlled drug release rates, thus significantly enhancing therapeutic efficacy and reducing side effects. This review focuses on the applications of various drug delivery forms, such as microneedle patches, implants, and tablets, in the treatment of cancers including breast cancer, melanoma, osteosarcoma, cervical cancer, colorectal cancer, and prostate cancer. Furthermore, the review explores the synergistic effects of combination therapies, such as photothermal therapy, chemotherapy, and immunotherapy, within 3D-printed drug delivery systems, and assesses their potential in addressing tumor recurrence, drug resistance, and treatment-related side effects. Despite the substantial promise of 3D printing technology in cancer treatment, challenges remain in material selection, process optimization, and production standardization. As technology continues to evolve and multidisciplinary collaborations deepen, 3D printing is expected to play an increasingly significant role in the future of precision medicine and personalized cancer therapy.

Biological tissues possess intricate hierarchical structures that enable diverse cellular functions, which are critical for maintaining physiological processes. Mimicking these properties is central to advancing tissue engineering and regenerative medicine. Aqueous two-phase systems (ATPS)-derived microgel bioinks have emerged as a versatile platform, offering biocompatibility, mechanical tunability, and multifunctionality for bioprinting applications. Recent advancements, such as oxygen-releasing constructs and modular designs, have demonstrated the potential of ATPS-derived microgel bioinks to create tailored cellular microenvironments, addressing challenges like oxygen delivery and tissue-specific integration while replicating the complexities of native tissues. This review synthesizes these advancements, critically discussing key considerations, including material selection, physicochemical properties, mechanotransduction, and stress-relaxation behavior. Future directions include advancing multi-scale fabrication techniques, refining cell-material interactions, and addressing scalability challenges to bridge the gap between research and clinical application. By providing a comprehensive perspective on the state-of-the-art in ATPS-derived microgel bioinks, this review emphasizes their potential to transform bioprinting and tissue engineering.

Developing physiologically relevant cardiac-engineered in vitro models has been a longstanding challenge in cardiac tissue engineering. Bioprinting technologies have been utilized to recreate the complex architecture of the human heart via the precise placement of cells and biomaterials. Concurrently, self-organizing cardiac organoids have emerged as powerful tools for developing cardiac tissues accurately mimicking the heart’s biological composition. This review explores the merging of these two rapidly evolving fields to produce functionally mature engineered cardiac tissues. Together, bioprinting can provide spatial control and mechanical support to guide cardiac self-organization, including strategies to directly print cardioids or incorporate them as modular units, while cardioid differentiation protocols promote multi-cellular complexity and developmental relevance to improve the functionality of engineered cardiac constructs. In this review, we discuss the key processing challenges and goals across the bioprinting workflow—spanning pre-processing, processing, and post-processing—and evaluate how they intersect with cell viability, structural integrity, and electromechanical function. We then explore the formation and functional features of self-organized cardioids, outlining major differentiation protocols, signaling cues, and functional outcomes. Finally, we propose a convergence between bioprinting and cardioid technologies to produce the next generation of in vitro cardiac models.

Biomedical research has long faced challenges in accurately replicating human organ microenvironments and overcoming interspecies biological differences, thereby limiting the in-depth understanding of physiopathological mechanisms and hindering the development of cutting-edge therapeutic approaches. Recently, novel technologies such as organoids, microfluidics, and three-dimensional (3D) bioprinting offer promising solutions, fostering innovation, and accelerating progress in biomedical science. However, none of these technologies alone can serve as a fully representative preclinical model, underscoring the need for integrated approaches. This review provides a comprehensive overview of various strategies combining microfluidics, organoids, and 3D bioprinting to develop more physiologically relevant preclinical models. After briefly introducing each technology, we examine the advantages of their pairwise integrations and discuss their prospects for drug research, disease modeling, and beyond. In addition, we explore the potential of combining all three technologies, including the emerging concept of 4D culture systems, which incorporate the temporal dimension to better mimic dynamic biological processes. We anticipate that these integrated models will propel significant advances in biomedical research and contribute to the transformation of future healthcare.

Cartilage and osteochondral tissues are vital tissues in the human body for normal activities. Cartilage and osteochondral defects represent prevalent clinical entities due to the limited regenerative capacity of the corresponding tissues. This growing disease burden underscores the urgent need for advanced therapeutic strategies facilitating both cartilage and osteochondral regeneration. With advancements in bioprinting technology, cartilage and osteochondral tissue engineering offers new hope for treatment. However, bioprinting of cartilage and osteochondral tissue still faces significant challenges, including replicating the mechanical properties and lubrication function of cartilage and osteochondral tissue, as well as mimicking the structural complexity of bone-cartilage tissues. In recent years, the development of innovative bioinks and novel bioprinting technologies has provided new solutions for the biomanufacturing of cartilage and osteochondral tissue. This article systematically reviews the latest developments in the field of bioprinting for cartilage and osteochondral tissue engineering, addressing potential directions, challenges, and covering topics, such as bioprinting techniques, bioinks, and recent advancements in cartilage and osteochondral regeneration. Through this article, future potential directions and existing challenges in the bioprinting of cartilage and osteochondral tissue can be further clarified.

Using selective laser melting, a metal three-dimensional (3D) printing technique, we developed bionic trabecular titanium alloy scaffolds with a micro-nano composite porous structure to address the limitations of traditional titanium implants. By integrating bionic design principles with advanced metal 3D printing strategies, these scaffolds mimic the trabecular network of cancellous bone, reducing elastic modulus (to ~4 GPa) and mitigating stress shielding. The bioprinted scaffolds exhibited enhanced surface properties that promoted Schwann cell (SC) adhesion, elongation, and spindle-like morphology, forming cellular networks along the microporous architecture. In contrast, SCs on solid titanium scaffolds displayed a flattened morphology with limited functionality. Transcriptomic analysis revealed that the scaffold’s micro-nano structure regulated SC behavior via the focal adhesion kinase-mitogen-activated protein kinase mechanotransduction pathway, enhancing the secretion of pro-osteogenic (e.g., platelet-derived growth factor with two A subunits) and pro-angiogenic (e.g., vascular endothelial growth factor) factors. Trabecular-like scaffold-conditioned medium significantly accelerated bone marrow mesenchymal stem cell proliferation, osteogenic differentiation, and endothelial cell angiogenesis, achieving a 36% higher healing rate compared to controls. While in vivo validation remains essential, our in vitro model isolates SC-driven mechanisms, avoiding systemic confounders. This study highlights the potential of 3D bioprinted scaffolds for personalized bone defect repair, offering a biomechanically and biologically optimized solution to enhance osseointegration.

Tissue engineering (TE) is a promising strategy to repair large bone defects by inducing endogenous bone regeneration. The ideal bone TE scaffold should possess high porosity (90%), suitable stiffness (1 MPa), and most importantly, a composition that mimics natural bone, including the same components (mineralized collagen) and cross-macro- and microscale structures. However, existing 3D-printed mineralized collagen bone TE scaffold hardly reproduces the cross-scale structure of natural bone, leading to low porosity (60%) and poor stiffness (100 kPa). To address this challenge, this study applied cryogenic 3D printing, also known as low-temperature field-assisted direct ink writing, to achieve 3D mineralized collagen scaffolds with cross-macro- and microscale structures. The inclusion of numerous micro-pores within the extruded fibers resulted in a porosity of 95%. In addition, through the control of scaffold microstructure and in situ mineralization, Young’s modulus of the cryogenic-printed collagen scaffold can be increased by 240% while maintaining the porosity at 95%, matching the properties of an ideal bone TE scaffold. In summary, this work provides new guidelines for technological innovation and application of cryogenic 3D printing, achieving a biomimetic mineralized collagen bone TE scaffold. In addition, the high porosity of the scaffolds produced by this technology enables these scaffolds to be used in various fields, including impact resistance, wave absorption, thermal insulation, flexible materials, and piezoelectric ceramics, among others.

Currently, traditional osteogenesis methods face significant challenges in terms of therapeutic efficiency and biocompatibility, particularly in the context of bone repair where higher precision and efficacy are required. In this study, we fabricated a novel composite scaffold composed of polycaprolactone (PCL), polydopamine (PDA), and iron oxide nanoparticles (IONPs) and investigated its osteogenic potential. The incorporation of IONPs imparts magnetic responsiveness to the scaffold, thereby enabling the application of an external magnetic field to stimulate osteogenesis. Characterization of the scaffold confirmed its structural integrity, porosity, and biocompatibility, whereas the inclusion of PDA improved its hydrophilicity and cell adhesion properties. In vitro studies demonstrated that an external magnetic field significantly enhanced cell proliferation, osteogenic differentiation, and mineral deposition of osteoprogenitor cells cultured on the scaffolds. Furthermore, in vivo evaluation revealed that when the scaffold was exposed to magnetic stimulation, bone regeneration was accelerated, and integration of the defect site was improved. The magnetic-field-mediated approach proposed in this study effectively enhanced the osteogenic rate by augmenting the magnetic responsiveness of IONPs and combining the biocompatibility and cell-adhesion-promoting functions of PCL/PDA. This method offers a more controllable and biologically responsive alternative strategy for bone tissue regeneration with considerable potential for clinical applications.

The development of bioinks with optimized printability, mechanical properties, and biocompatibility is critical for advancing three-dimensional (3D) bioprinting and tissue engineering. In this study, we introduce an alginate/gelatin/dextran-aldehyde (AGDA) bioink, designed to balance structural integrity and cellular functionality. Among the tested formulations, AGDA1 demonstrated superior performance, with optimized printability and high cell compatibility. AGDA bioinks involve dual crosslinking (ionic gelation of alginate and Schiff base formation between gelatin and dextran-aldehyde), permitting appropriate stiffness, viscosity, and thixotropic behavior. Fibroblasts encapsulated in AGDA, either as single cells, spheroids, or a combination of both, exhibited high viability and proliferative capacity. Notably, the combination method supported the highest cellular density and fibroblast-specific morphological transformations, surpassing the commercially available GelXA bioink. These findings highlight AGDA’s potential as a versatile bioink for fabricating complex and scalable tissue constructs. In summary, this study contributes to the development of bioinks tailored for enhanced cell engraftment and regenerative applications.

The natural extracellular matrix (ECM) exhibits remarkable viscoelasticity and stress relaxation. Constructing viscoelastic scaffolds that can precisely control the stress relaxation rate and possess good biocompatibility is a key challenge in the design of tissue engineering scaffolds. Understanding the factors influencing the viscoelasticity of scaffolds and their mechanisms, as well as implementing comprehensive regulatory strategies based on this understanding, are effective methods for precisely controlling the stress relaxation rate. Current research on viscoelastic scaffolds mainly focuses on the regulation of bulk hydrogel viscoelasticity, while the impact of 3D printing parameters on stress relaxation time remains underexplored. In this study, we controlled the structure and morphology of silk fibroin to obtain a crystalline silk fibroin fiber (SL) solution, which was then mixed with gelatin solution to achieve high-precision printing of low-concentration (<2%) silk fibroin. Based on this, we explored the effects of printing angle, fiber diameter, and porosity on the stress relaxation rate and elastic modulus of the scaffold. Specifically, as porosity increases, the relaxation rate tends to rise, while the elastic modulus decreases. Conversely, as the printing angle and fiber diameter increase, the relaxation rate significantly decreases, and the elastic modulus correspondingly increases. We verified these effects using alginate-based bioink, demonstrating the universality of the influence of printing parameters on scaffold viscoelasticity. Additionally, we constructed scaffolds with similar elastic moduli but different stress relaxation rates and investigated their effects on cell growth, thereby confirming the good biocompatibility of viscoelastic scaffolds. This study not only provides a theoretical basis for precisely controlling the stress relaxation rate of 3D-printed viscoelastic scaffolds but also offers new insights for the design and optimization of tissue engineering scaffolds.

Treating large-sized infectious bone defects is currently one of the most urgent clinical challenges that need to be addressed in clinical practice. The clinical application of autologous and allogeneic bone grafts faces numerous persistent challenges that remain unresolved. Therefore, there is an urgent need to develop a bone repair scaffold capable of large-scale production, safe for in vivo use, and possessing robust bone repair and anti-infective properties. In this study, a 3D-printed bone repair scaffold was fabricated using a polycaprolactone (PCL) and magnesium phosphate (MgP) composite material. The scaffold subsequently underwent surface modification with the antimicrobial peptide Tet213 with a DOPA tail, ultimately leading to the development of a novel bone repair scaffold named DTet213@PCL/MgP. The experimental results demonstrated that the DTet213@PCL/MgP scaffold exhibited outstanding antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), along with superior proliferation and osteogenesis capabilities for MC3T3-E1 preosteoblastic cells. In a rat radial defect model, the scaffold effectively induced new bone formation at the defect site, resulting in rapid bone regeneration. Furthermore, histopathological examination (HE staining) of major organs confirmed the excellent in vivo biocompatibility and safety profile of the DTet213@PCL/MgP scaffold. In the future, the DTet213@PCL/MgP scaffold represents a novel solution for the treatment of large-scale infected bone defects, capitalizing on its dual functionality in osteogenesis and infection control.

Bioprinting is an emerging additive manufacturing process that offers great potential for fabricating living tissue by precisely printing cells and biomaterials onto various substrates. This technique can imitate native tissue functions, enabling clinical trials to explore new pathways for regenerative medicine. Among various bioprinting techniques, laser-induced forward transfer (LIFT) offers a high spatial resolution, accurate and controlled bio-ink deposition, and high post-printing cell viability. Effective bioprinting requires a deep understanding of material properties, especially the rheological behavior of bio-inks, which is critical for achieving the desired outcomes. Rheological characterization of these materials is essential for understanding their behavior under bioprinting conditions. The LIFT technique utilizes a wide range of soft biomaterials, generating printed structures containing cells, which proliferate for several days post-printing. These biomaterials can be controllably deposited in a variety of substrates. In this study, two cell-laden bio-inks with low and high number cell densities were printed at controlled depths within an extracellular matrix (ECM) by adjusting the laser energy. This process allows precise immobilization of cells at desired depths within the ECM using light and a proper optical setup. The rheological behavior of all bio-inks was analyzed using a microfabricated rheometer-viscometer on a chip. To investigate the transfer dynamics, a high-speed camera was integrated into the LIFT setup, monitoring the immobilization phenomenon within the ECM, and highlighting important characteristics of the jet propagations during printing. The morphological characteristics of the two sequential and distinct cell-laden jets were examined in detail during the printing process. This study showcases the ability to precisely deposit cells up to 2.5 mm deep within a soft matrix substrate, fabricating any desired cell-laden architecture for bio-engineering applications.

Assessing the positioning of prostheses after surgery is essential for evaluating therapeutic efficacy and optimizing surgical methods in three-dimensional (3D)-printed patient-specific acetabular revision implants. However, the lack of an effective 3D accuracy assessment framework for these customized implants has impeded the development of standardized benchmarks for verifying spatial alignment between intraoperative placement and preoperative digital planning. To bridge this gap, we introduce a novel evaluation system that integrates point localization, vector-based angular assessment, and volumetric overlap analysis to comprehensively quantify alignment between implanted prostheses and preoperative templates. Patients were classified into cohorts according to postoperative Harris Hip Scores (HHS) and complication profiles, differentiating a “better outcome” group (HHS ≥ 80, no major complications) from a “regular outcome” group. A computed tomography (CT)-based pelvic 3D coordinate system, established through anatomical landmarks, facilitated comparative analyses of intergroup variations in positional deviation, angular deviation, and volumetric overlap accuracy. The system’s reliability was confirmed via inter- and intra-observer consistency tests. Findings revealed outstanding measurement consistency (κ > 0.8). Compared to the regular outcome group, patients with better outcomes demonstrated significantly lower positional deviations (p < 0.001) and angular deviations (p = 0.003), along with superior volumetric overlap accuracy (p < 0.001). This CT-guided stereotactic assessment system offers a clinically relevant, high-fidelity approach for evaluating postoperative implant placement in 3D-printed acetabular prostheses. Notably, it represents the first validated methodology leveraging a pelvic 3D coordinate framework for a comprehensive analysis of preoperative planning versus postoperative implant positioning.

Nasopharyngeal carcinoma (NPC) is a prominent head and neck malignancy, yet the mechanisms underlying its occurrence, progression, recurrence, metastasis, drug resistance, and radiation resistance have not been fully understood. This knowledge gap is partly due to the lack of preclinical NPC models for research. Compared to traditional 2D cell cultures, 3D bioprinting (3DP) offers significant advantages in replicating the tumor microenvironment. However, no studies to date have used 3DP technology to model NPC. In this study, we used extrusion-based 3DP to develop a new preclinical NPC model (3DP-HK1) using the emerging bio-ink gelatin methacryloyl. The model successfully demonstrated the ability to sustain long-term tumor cell activity. Immunohistochemistry and immunofluorescence analyses demonstrated that 3DP-HK1 largely retained the histopathological features and tumor-related protein expression of NPC. In addition, we conducted a wound healing experiment, which indicated that tumor cells in 3DP-HK1 have stronger migration ability than 2D-cultured cells (2D-HK1), highlighting differences in cellular phenotype. The different responses of 3DP-HK1 and 2D-HK1 to various anti-tumor drugs and radiation reflect the advantages of 3DP-HK1 for preclinical drug screening and exploring mechanisms of radiotherapy in NPC. Transcriptome sequencing revealed that 3DP-HK1 has a distinct gene expression profile compared to 2D-HK1, with significantly upregulated expression of malignant genes, such as keratin 6B (KRT6B), S100 calcium-binding protein A8 (S100A8), and crystallin alpha B (CRYAB). Meanwhile, genes associated with drug resistance (e.g., lysine demethylase 5B [KDM5B]) and radiation resistance (e.g., carnitine palmitoyltransferase 1A [CPT1A]) were also upregulated, confirming findings from other experimental analyses at the RNA level. In conclusion, this study successfully constructed a 3DP-based preclinical model for NPC research and proved its reliability and significant potential for advancing drug screening and mechanistic studies.

Additive manufacturing holds significant potential in the field of tissue engineering, particularly for healing, replacing, and regenerating damaged or diseased tissues. However, the high cost of commercially available bioprinters and the limited availability of suitable biomaterials for bioprinting have hindered its widespread implementation and practical application in clinical settings. The aim of this study was to identify printing parameters tailored to the viscosity of the bioink and the evaporation characteristics of the organic solvent used in its formulation, with the broader goal of developing a cost-effective and accessible bioprinting platform for scaffold fabrication. To this end, we present a novel approach involving the design and fabrication of a cost-effective three-dimensional (3D) bioprinter conversion kit, developed using commercially available 3D printers. Bioprinting high-viscosity bioinks present specific challenges due to their resistance to flow and a high tendency to clog printing nozzles; however, this issue was mitigated through comprehensive rheological characterization. By leveraging the favorable properties of cellulose acetate as the chosen biomaterial, scaffold fabrication via 3D bioprinting was achieved efficiently without the need for curing or post-processing steps. Furthermore, a parametric troubleshooting procedure was developed to optimize printing parameters, elucidate the material behavior, and improve scaffold resolution, as assessed through scanning electron microscopy. Additionally, preliminary cell culture studies were carried out to evaluate the influence of the printed scaffolds’ biophysical cues on cellular responses, including adhesion and proliferation. This innovative and cost-effective solution has great potential to support researchers in tissue engineering and facilitate further exploration of advanced bioprinting techniques.

The orthopedic potential of biodegradable iron (Fe)-manganese (Mn)-copper (Cu) alloys remains insufficiently defined, necessitating comprehensive investigation into their mechanical properties, wear resistance, magnetic resonance imaging compatibility, biodegradation behavior, antibacterial efficacy, cytocompatibility, and osteogenic differentiation capacity. This study systematically addresses these aspects through microstructural characterization, mechanical testing, and biological evaluations of Fe-30Mn-6Cu alloy fabricated via selective laser melting (SLM). For comparison, a Cu-free Fe-30Mn alloy was fabricated under similar SLM conditions. The incorporation of 6 wt.% Cu into Fe-30Mn stabilized the γ-austenite phase, enhanced yield strength, improved wear resistance, accelerated electrochemical biodegradation, and imparted strong antibacterial activity. The SLMed Fe-30Mn- 6Cu (i) exhibited a fully γ-austenite microstructure with fine equiaxed grains (~7 μm) containing Cu-enriched intergranular second-phase particles; (ii) demonstrated a yield strength of ~230 MPa—approximately ~24% higher than that of SLMed Fe- 30Mn—along with improved tribological performance, a reduced hysteresis loop area indicating extremely low saturation magnetization and magnetic susceptibility, and a biodegradation rate three times higher compared to the Cu-free counterpart; and (iii) achieved a bacteriostatic rate exceeding 99% against Escherichia coli and Staphylococcus aureus, alongside excellent cytocompatibility and promotion of osteogenic differentiation in MC3T3-E1 cells. These findings provide insights into the structure-property-function relationship of multifunctional Fe-Mn-Cu alloys and their promising applicability in orthopedic implants.

3D printing technology is widely used for creating magnetic resonance imaging (MRI) phantoms, mimicking tissue, and contrast levels found in real patients. Traditionally, 3D-printed structures were filled with gels containing contrast agents. Recently, studies have shown that some 3D-printed materials can be directly used to create MRI phantoms. However, each material typically produces a unique MRI signal, requiring specific materials for desired contrasts, or a single material can produce various contrasts, but these often do not match the properties of different soft tissues. In this study, we aimed to investigate MRI signal properties of 3D-printed phantoms made of silicone in MRI. We determined the MRI relaxation times of extrusion silicone 3D-printed phantoms from different materials with different infill densities and correlated them with the reference values in soft tissues. We also evaluated the performance of our approach using realistic tumor phantoms. A reproducibility analysis as well as longitudinal stability analysis was also performed. The experimental results showed that the 3D-printed silicone phantoms could achieve MRI signal properties with good correspondence to a range of soft tissues and organs (T1 relaxation time range from 850.8 to 1113.3 ms and T2 relaxation time range from 22.6 to 140.7 ms). Our results demonstrated good stability of the T1 and T2 values over time and also good agreement for the replicas compared to the original samples, confirming the reproducibility of the printed materials. A good agreement was observed between the MRI signal property in tumor phantoms and the reference values of invasive ductal carcinoma of the breast in patients.

Bioprinting is an emerging technology with significant potential in biomedical fields, enabling the creation of highly customized, cell-laden constructs. Despite the promise, achieving high-quality, reproducible prints remains challenging due to the lack of standardized protocols, which has hindered the widespread adoption of the technique. In this study, we present a systematic bioprinting protocol designed to optimize the performance of an in-house photo-curable biomaterial ink composed of gelatin methacryloyl and egg white protein. Printing quality was evaluated through the following three key assessments: extrusion, deposition, and printability. To facilitate accurate image analysis, we developed a custom three-dimensional (3D)- printed lens support specifically designed for a USB microscope. Additionally, we implemented a Python script to quantitatively assess bioprinting quality. Our results indicate that a pressure range of 70-80 kPa, combined with speeds between 300 and 900 mm/min, yields reliable extrusion flow, with 75 kPa and 600 mm/min emerging as optimal parameters for bioprinting 3D constructs. These findings underscore the importance of carefully tuning parameters—including pressure and speed—to achieve stable, high-resolution extrusions. Such optimization mitigates common printing issues, including tip clogging, filament dragging, and unintended merging of adjacent filaments, thereby enhancing structural accuracy. This work provides a comprehensive framework for evaluating and optimizing bioprinting parameters, offering a reproducible methodology to enhance print quality. It contributes to ongoing efforts to standardize bioprinting processes and advance their applications in tissue engineering and regenerative medicine.

Critical bone defect repair remains a major challenge in orthopedics. Cynomorium songaricum polysaccharide (CSP), derived from the traditional medicinal plant Cynomorium songaricum Rupr. in China, demonstrates excellent anti-inflammatory and osteogenic properties. Given these promising biological activities, we developed a novel therapeutic approach using a hydrogel composite scaffold incorporating CSP (GAC-C) for treating critical-sized bone defects. The composite scaffold was fabricated by embedding CSP into a methacrylated gelatin (GelMA)/sodium alginate (SA)/carboxymethyl chitosan (CMCS) blend via three-dimensional (3D) printing technology. The structural, mechanical, and biological properties of GAC-C were characterized, and osteogenic performance was evaluated both in vitro with rat bone marrow stromal cells (rBMSCs) and in vivo using a critical-sized bone defect model. Results indicated that the GAC-C scaffold demonstrated excellent biocompatibility, promoted osteogenic differentiation of rBMSCs, and enhanced bone integration and repair. Thus, the GAC-C scaffold has the potential for effectively repairing criticalsized bone defects.

Excessive inflammation remains a major impediment to the clinical repair of critical-sized bone defects, with the immune micro-environment playing a pivotal role in osteogenesis. An appropriate local immune response following biomaterial implantation is essential for successful bone tissue regeneration. In this study, a hydroxyapatite/montmorillonite nanoclay/polycaprolactone (HNP) composite scaffold was designed and subsequently fabricated using three-dimensional (3D) printing, with the aim of modulating macrophage polarization and promoting bone regeneration. The resulting HNP scaffold exhibited favorable mechanical strength and significantly promoted bone marrow mesenchymal stem cell adhesion, proliferation, secretion of osteogenic cytokines, and osteogenic differentiation. Moreover, it modulated the bone immune micro-environment by suppressing M1 macrophage polarization and promoting a shift toward the M2 phenotype, thereby establishing a pro-osteogenic immune milieu. In vivo studies using a rat calvarial defect model demonstrated that, compared with other groups, the HNP scaffold markedly enhanced M2 macrophage polarization, promoted angiogenesis, and accelerated new bone formation. Overall, the 3D-printed HNP scaffold effectively regulated the immune micro-environment and facilitated both bone regeneration and neovascularization, highlighting its strong potential as a candidate for bone tissue engineering applications.

Lymphedema is a condition resulting from impaired lymphatic function, with limited effective treatment options available. This study investigates the potential of 3D-bioprinted scaffolds, utilizing biomaterials and human adipose-derived stem cells (hADSCs), as a novel approach to promote lymphangiogenesis and improve treatment outcomes in lymphedema. Scaffolds were characterized for cell viability, mechanical properties through compressive strength testing, and structural integrity after printing. In vivo therapeutic effects were assessed in Sprague-Dawley rats through fluorescence imaging, histopathological analysis, and immunofluorescence staining. Additionally, protein and gene expression of lymphangiogenic markers (LYVE-1, VEGF-C, VEGF-A) were analyzed using Western blotting and quantitative polymerase chain reaction. The scaffolds demonstrated high cell viability, structural integrity, and mechanical stability, with enhanced cell distribution and extracellular matrix deposition over time. Scaffolds containing hADSCs showed the most lymph node-like characteristics, with a well-defined capsule and increased lymphocytic infiltration. Immunofluorescence analysis revealed enhanced expression of LYVE-1, Prox1, and CD31, indicating significant lymphatic and vascular remodeling. Additionally, upregulation of LYVE-1, VEGF-C, and VEGF-A protein and mRNA levels highlighted the scaffolds’ potential in promoting lymphangiogenesis and angiogenesis. These findings highlight the significant potential of hADSCs-loaded scaffolds in enhancing tissue regeneration, particularly in restoring lymphatic function in lymphedema.

Three-dimensional (3D)-bioprinting is widely used in tissue engineering due to its customizability, avoidance of allogeneic rejection, and absence of disease transmission risk. Cellulose, a renewable natural polymer, is valued as an excellent bioink for its non-toxicity, biocompatibility, biodegradability, and cost-effectiveness. In this study, 2,2,6,6-tetramethylpiperidine-1-oxyl radical-oxidized microcellulose was subjected to homogenization. The resulting bioink was characterized using Fourier transform infrared spectroscopy, conductivity measurements, and rheometric analyses. Scaffolds were subsequently fabricated using 3D bioprinting, and cell viability was evaluated through cell culture on the printed scaffold. Optimization of the oxidation process revealed that a 6-h treatment achieved the highest degree of oxidation, exhibiting superior viscosity and printability compared to other durations. A straightforward scale-up of the 6-h process enabled the successful fabrication of 3D-bioprinted scaffolds. Cell culture experiments demonstrated excellent cell adhesion and viability on the scaffolds. Our findings demonstrate that oxidized microcellulose serves as a promising bio-based, non-toxic, structurally stable, and cell-compatible bioink for 3D bioprinting in tissue engineering applications.

Translational medicine for neurodegenerative diseases can advance through the use of in vitro models incorporating human neural cells derived from patient-specific induced pluripotent stem cells (iPSCs). Previously, we investigated whether motor neuron (MN) progenitors derived from human iPSCs could differentiate from MNs within three-dimensional (3D)-printed scaffolds. While extensive neurite arborization was observed on the scaffold surface, no neurite outgrowth occurred within the scaffold interior. Here we showed the extensive growth of the neurites from iPSC-derived neural progenitors, imbedded into the gelatin scaffolds during 30 days of experimental time. We presented a bioink formulation that softens the scaffold while preserving its 3D structure, thereby facilitating neurite outgrowth throughout the scaffold. MN differentiation, evidenced by extensive neurite arborization and the expression of choline acetyltransferase (ChAT), was verified in 3D images deep within the scaffold structure. Notably, the degree of MN differentiation appeared to depend on two factors as follows: the delivery of MN differentiation factors via mesoporous silica particles (MSPs) embedded in the bioink and the method used to generate MN progenitors prior to 3D printing. In this paper, we provide a detailed protocol for 3D-printing human iPSC-derived MN progenitors, enabling their differentiation and survival within gelatin scaffolds. This protocol could be expanded to incorporate additional cell types, allowing the creation of more complex and standardized 3D neural tissues. Such advancements could facilitate investigations into the pathophysiology of motor neuron diseases and the development of new therapeutic strategies.

Traditional monolithic microfluidic devices are constrained by their inability to accommodate modifications to circuit elements, necessitating complete redesign and refabrication. To address these limitations, this study introduces modular microfluidic connectors fabricated via stereolithographic (SL) 3D printing. We designed and evaluated three distinct connector types—tessellated, sponge, and solid-walled—using tailored photoresins to enhance reusability, flexibility, and sealing performance. The tessellated connectors, printed with poly(ethylene glycol) diacrylate (PEGDA; Mw ~258) and incorporating an octet unit cell structure, reduced the rigidity of PEGDA prints, improving reusability under moderate conditions. The sponge connectors, fabricated from a PEGDA and 2-hydroxyethyl acrylate (2-HEA; Mw ~116) blend (2-HEA-co-PEGDA), exhibited greater flexibility; however, swelling in aqueous environments may limit their long-term utility. In contrast, the solid-walled connectors, produced with commercial Asiga Soft Resin, demonstrated superior reliability and adaptability, as validated in a reconfigurable concentration gradient generator with scalable output capabilities. Cytocompatibility tests confirmed that PEGDA-printed devices, following isopropanol and ultraviolet post-processing, are suitable for bioanalytical applications that do not require incubation. These findings establish SL 3D printing as a promising method for developing flexible, reconfigurable microfluidic platforms, with potential uses in material synthesis, chemical analysis, and point-of-care diagnostics. While challenges related to environmental durability persist, these advances lay the foundations for developing more robust and adaptable microfluidic systems with versatile applications.