The Coronavirus Disease of 2019 (COVID-19) pandemic caused by SARS-CoV-2 resulted in widespread mortality, economic strain, and healthcare system disruption, highlighting the need for effective strategies to address viral threats. Tissue engineering and biomaterials can contribute significantly in advancing our understanding and treatment of respiratory viral infections by developing physiologically relevant in vitro models, controlled and targeted drug delivery systems, and effective next-generation vaccine platforms. Over the last 5 years, tissue-engineered cell-based models, including organ-on-a-chip systems, have improved our understanding of viral entry, immune response, and therapeutic efficacy in pulmonary, cardiac, neurological, and vascular tissue. Biomaterial-based delivery systems have enhanced the targeting, bioavailability, and sustained delivery of therapeutics such as antivirals, monoclonal antibodies, nucleic-acid-based vaccines, and anti-inflammatory drugs, while also reducing or eliminating system toxicity and our reliance on intravenous administration. Advancements in vaccine platforms using lipid nanoparticles, protein scaffolds, and vesicular or cell-based platforms are in different phases of development to stimulate more robust responses against emerging SARS-CoV-2 variants. Collectively, these advancements highlight the influence of tissue engineering and biomaterials in SARS-CoV-2 research and treatment. This review provides an overview of recent developments in in vitro modeling, drug delivery systems, and vaccine platforms, highlighting their future role in improving clinical outcomes, managing variants, and preparing for potential future pandemics, including addressing challenges in infrastructure such as limited access to high-containment biosafety facilities used to study emerging infectious pathogens.Impact StatementDuring the COVID-19 pandemic, we introduced basic tenets of virology to a tissue engineering audience and proposed different areas in which the field could contribute to developing diagnostics and therapeutics for respiratory viral infections. In this 5-year update, we highlight how tissue engineers and biomaterial scientists contributed tools to dissect virus pathophysiology and deliver therapies such as mRNA vaccines to prevent mortality during the pandemic. With the emergence of new variants and the threat of new respiratory viral pandemics, tissue engineers can continue to play important roles in virology.
In bone regenerative medicine, scaffolds play a pivotal role in promoting cell adhesion, proliferation, and differentiation. Among the various materials employed for creating scaffolds, mixed materials composed of poly-l-lactic acid and hydroxyapatite (PLLA/HA) have emerged as a favored option owing to their biodegradability, biocompatibility, and ability to support cellular activities. Our research has delved into the optimization of PLLA/HA scaffold design, with a particular focus on pore size, as it significantly influenced cellular behavior. We have found that PLLA/HA scaffolds with the pore size of 400 µm, created using selective laser sintering, exhibited the most favorable conditions for cell adhesion, proliferation, and osteogenic differentiation. Additionally, flow field environment simulation showed that scaffolds with the pore size of 400 µm possessed a more balanced flow field distribution, which was beneficial to cells. This finding provides research support for the pore size selection of bone scaffold in advanced treatment strategies for bone tissue engineering.
Adipose tissue is a highly plastic organ whose remodeling dynamics are central to whole-body metabolic health. Expansion of white adipose tissue occurs through either hyperplasia, which preserves tissue function, or hypertrophy, which causes local hypoxia, inflammation, and pathological extracellular matrix (ECM) accumulation. Under hypertrophic conditions, the ECM stiffens and transitions from a supportive scaffold to a fibrotic barrier that limits expansion and perpetuates metabolic dysfunction. Understanding how mechanical cues regulate adipose tissue remodeling is, therefore, essential for identifying new therapeutic strategies. Two mechanosensitive cell populations, adipose stem cells (ASC) and mature adipocytes, are central to this process. ASC interpret ECM stiffness and compositional changes, which determine lineage outcomes. Soft and flexible matrices favor adipogenesis, whereas stiff matrices drive fibroblast-like activation and matrix deposition. Adipocytes, though differentiated, retain mechanosensitive signaling capabilities that shape their function. Under chronic mechanical stresses, cytoskeletal remodeling pathways lead to changes in gene expression and partial dedifferentiation toward a fibroblast-like phenotype. Reciprocal signaling between ASC and adipocytes amplifies these processes, establishing feedback loops that reinforce either healthy or pathological remodeling. Cell and tissue engineering approaches are essential for dissecting these processes, with hydrogel substrates, 3D scaffolds, compression assays, and atomic force microscopy offering physiologically relevant platforms to model progenitors and adipose tissue cellular mechanics. Emerging tools, including nanotopography and mechanical stimulation devices, have the capacity to further clarify how mechanical signals influence adipose remodeling. By positioning ASC and adipocytes as active regulators of ECM mechanics, we underscore the importance of mechanotransduction pathways in adipose tissue health and point to bioengineering strategies that may help discover ways to restore tissue flexibility and improve metabolic outcomes.
Developmentally inspired tissue engineering strategies are increasingly being employed to generate biomimetic articular cartilage (AC) grafts. One such approach leverages the capacity of stem or progenitor cells to self-organize and generate microtissues or organoids, which can then be used as biological building blocks to fabricate larger grafts of clinically relevant size. While human mesenchymal stem/stromal cells (hMSCs) can be used to generate cartilage-like microtissues, they are often fibrocartilaginous in nature and/or have an inherent tendency to become hypertrophic and progress along an endochondral pathway. In this study, a gene silencing approach was explored to engineer hyaline cartilage microtissues by delivering the prochondrogenic factor, antimicro ribonucleic acid 221 (anti-miR-221), using a polymeric nonviral vector. Effective silencing of micro ribonucleic acid 221 (miR-221) was observed for a range of doses, while selected anti-miR-221 concentrations supported type II collagen deposition while simultaneously suppressing the production of type X collagen within the cartilage microtissues. In addition, large numbers of such "silenced" chondrogenic microtissues could be fused into larger grafts, with the resulting constructs again showing no signs of early hypertrophy. To conclude, miR-221-silenced hMSCs support the development of hyaline cartilage microtissues rich in type II collagen, which could be used as in vitro models of AC or as biological building blocks in the engineering of scaled-up regenerative grafts.
Ischemic cardiac injury, arising due to myocardial infarction (MI), ischemia-reperfusion injury (IRI), and other ischemia-associated forms of cardiac damage, remains a major clinical challenge. The irreversible loss of cardiomyocytes from within the myocardium, together with oxidative stress and inflammation, creates a complex post-MI milieu that is not readily addressed by existing therapeutic strategies. Cardiac tissue engineering solutions that combine advanced biomaterials with either stem cell-derived cardiovascular cells, their derivatives (such as extracellular vesicles and exosomes), or other bioactive compounds (including chemokines and cytokines) are being developed to repair and regenerate the infarcted human heart. This review highlights the state-of-the-art strategies that utilize cutting-edge technologies to develop tissue-inducing biomaterial solutions for cardiac regeneration and repair, with particular emphasis on (i) integrating biomaterials with cells in strategies undergoing clinical investigation, (ii) incorporating cellular derivatives into biomaterial scaffolds, and (iii) designing and evaluating intrinsically functional biomaterials. This review aims to provide both a theoretical foundation and future perspectives for the innovation and optimization of next-generation tissue-inducing biomaterial-based strategies for cardiac tissue regeneration and repair.
Vascularization and perfusion are essential for tissue engineering of large-scale bioartificial tissues and organs. Both fluid flow and hypoxia have been shown to influence capillary tube formation in bioartificial matrices. However, the ideal timing and combination of these two factors for optimizing capillary tube formation in tissue engineering approaches still remains unclear to date. Capillary tube formation was evaluated in 3D flow chamber wells, in which human microvascular endothelial cells (HMVEC) and adipogenous stem cells (ASCs) suspended in fibrin-based tissue matrices were exposed to fluid flow and hypoxia under defined conditions. Here, both factors were either applied alone or in combination, either from the beginning of the incubation period or after initial capillary tube formation on day 3. Capillary tube formation was analyzed by fluorescence microscopy and quantified two times on days 3 and 6. Furthermore, large-scale fibrin matrices surrounded a perfused microchannel under selected conditions. Exposure of HMVEC in fibrin-based matrices to flow and hypoxia alone or in combination immediately from the beginning of the in vitro culture resulted in impaired capillary tube formation compared with static or normoxic culture conditions in all settings. When initiated after initial tube formation under static conditions for 3 days, exposure to physiological fluid shear stress with or without parallel exposure to hypoxia was associated with significantly increased network complexity. The inhibition of capillary tube formation by continued fluid flow could be compensated for by adding exposure to hypoxia after 3 days of initial tube formation. The impact of both fluid flow and hypoxia was highly dependent on the timing of onset as well as their application alone or combined. Both fluid flow and hypoxia were identified as potent tools for regulating capillarization in vascular tissue engineering, but timing and combination are crucial for optimized in vitro tube formation.Impact StatementThe integration of a vascular network providing oxygen and nutrient supply throughout large-scale bioartificial tissues remains a major challenge in tissue and organ engineering. We here provide a timing-specific analysis of the impact of fluid flow and hypoxia on in vitro capillary tube formation with or without static and normoxic preincubation. With this, the ideal timing and combination of flow and hypoxia for capillary tube formation were identified. These insights can be used to refine the perfusion and culture strategies for tissue engineering of vascularized constructs and thus, optimize in vitro prevascularization of large-scale bioartificial tissues and organs.
Because articular cartilage (AC) lacks inherent repair capacity, research has focused on translating tissue-engineered cartilage to the clinic. Toward this, rapid and nondestructive methods would be useful for determining in-process and release characteristics during the manufacture of tissue-engineered products. The current work aims to introduce a Raman-based methodology for nondestructive qualitative and quantitative characterization of tissue development using AC. First, Raman shifts associated with critical biochemical components of AC, with particular emphasis on DNA, glycosaminoglycans (long chains of sugar molecules and a key component of cartilage), total collagen, as well as pyridinoline (a marker of collagen crosslinking and maturation), were collated. Next, verification of the molecular spectroscopic biomarkers was conducted by temporally tracking tissue maturation/development of nascent and mature AC, establishing a temporal reference dataset. Finally, validation was performed by correlating the spectroscopic biomarkers with traditional photometric biochemical assays and mass spectrometry. The results presented here include a Maturity Index for quantification of tissue development/maturation. Strong correlations were found between nondestructive spectroscopic-based measurements and destructive (photometric and mass spectrometric) measurements with high linearity for both nondestructive Raman (R2 > 0.96) and destructive biochemical (R2 > 0.97) assays, respectively. Uses of the proposed rapid and nondestructive method include in-line quality assessment (in which the sample is not removed from the process stream) to monitor the manufacturing of tissue-engineered medical products. This study shows that Raman spectroscopy has the capacity of being a powerful tool for nondestructive quality control and assurance in traditional biomanufacturing workflows, and the approach taken here may also be utilized as a template and research tool for studies on the development of other native and engineered tissues.
Traditional approaches to tissue-engineered small intestine (TESI) require implanting a construct in the omentum of the abdominal cavity to allow for vascularization of the construct and tissue maturation. A second operation is then needed to implant the construct in continuity with the intestine. The timing of the second operation has historically been chosen based on predetermined biological endpoints. Currently, no well-validated method has been used to noninvasively monitor for vascular maturity which would better inform when the second operation should be performed. We hypothesized that photoacoustic imaging (PAI) could serve as a tool to noninvasively monitor regional and temporal changes in vascular maturity in scaffolds implanted in the omentum. For this pilot study, tubular scaffolds used for TESI were fabricated with electrospinning and implanted in the omentum of Sprague-Dawley rats for 1 and 2 months. Scaffolds were imaged with PAI and tissue oxygenation and hemoglobin concentration were quantified. PAI was then correlated with gross observations of vascularization at each time point. PAI was able to determine regional and temporal changes in tissue oxygenation and hemoglobin concentration. Specifically, the oxygenation and hemoglobin concentration of the top wall of the construct showed better vascular maturity compared with the bottom wall. In addition, vascular maturity seemed to improve in the top wall from 1 to 2 months. The bottom wall was not well covered by the omentum and thus did not vascularize as well as the top wall. The PAI findings were confirmed on gross examination of the scaffolds and upon quantification of the histological analysis of endothelial cell density. Thus, PAI may serve as a critical tool for monitoring vascular maturity in TE, specifically within the abdomen. This will be a critical tool in the preclinical development and clinical translation of TESI.Impact StatementImaging methods to track functional changes in tissue-engineered constructs are need. These critical tools will be essential for tissue-engineered small intestine (TESI) development and clinical translation. In particular, understanding when a TESI construct has achieved vascular maturity is required prior to placing the TESI in connection with native intestine. In this proof-of-concept study, we have shown that photoacoustic imaging can be used to noninvasively track construct vascular maturity and that the imaging correlates with end-point histology. In addition to TESI, this tool is broadly applicable to all tissue-engineered constructs.
The liver is a multifunctional organ essential for detoxification, protein synthesis, glucose regulation, bile secretion, and drug metabolism. However, persistent damage leads to chronic inflammation, excessive extracellular matrix deposition, and progressive fibrosis culminating in cirrhosis, for which liver transplantation remains the only curative option. Yet, the scarcity of donor organs and risks of immune rejection underscore the urgent need for physiologically relevant in vitro liver models to investigate pathogenesis and facilitate therapeutic discovery. Current two-dimensional cultures and animal models fail to recapitulate the multicellular interactions that govern liver homeostasis and disease progression. Hepatocytes (Heps) constitute the primary parenchymal population, while hepatic stellate cells (HSCs) and liver sinusoidal endothelial cells (LSECs) coordinate fibrogenic, angiogenic, and regenerative responses. Dysregulation of this crosstalk drives fibrosis and architectural collapse, highlighting the necessity for multicellular systems that mimic native liver complexity. In this study, we established a three-dimensional (3D) microtissue platform that recapitulates both the structural and functional characteristics of the human liver. Human-induced pluripotent stem cells (hiPSCs) were differentiated into Heps, HSCs, and LSECs, which were subsequently cocultured within a self-organizing 3D microenvironment. We successfully reconstructed a miniaturized liver model that maintains hepatic functionality and exhibits steatogenic responses to alcohol exposure. This hiPSC-derived microtissue enables the modeling of chronic liver diseases, intercellular signaling, and fibrogenic pathways, thereby providing a translationally relevant system for mechanistic studies, drug toxicity testing, and personalized therapeutic development.
Cartilage and osteochondral disorders pose an increasing clinical, economic, and social challenge. With an aging population, there is a need to develop innovative, nonsurgical strategies for treating defects, fractures, and other osteochondral disorders. Bone implants require surgical intervention, carry a risk of complications, are expensive, and do not always provide comfort to the patient. Alternatively, stimulation of bone regeneration using synthetic peptides is a promising and less invasive option in the treatment of trauma, orthopedics, craniofacial surgery, and dentistry. In the present study, we evaluated the biological effects of two peptides: the novel peptide UG27 and CDP4 derived from the protein Cpne7 (Copine 7), on the activity of adipose tissue-derived mesenchymal stem cells. Using labeling, differentiation, and imaging methods, we demonstrated the effect of UG27 on viability, biomineralization, extracellular matrix, and calcium salt growth in osteocytes. The peptides were immunologically safe and stimulated cell migration without showing any cytotoxic effects. The peptide, UG27, has an active connection with the biomaterial and is a promising compound in bone injury therapies.
Stem cell-derived extracellular vesicles (EVs) play a crucial role in intercellular communication and reflect the functional characteristics of their parent cells. Despite the significant therapeutic potential of these EVs, the molecular features of EVs derived from different stem cells and their relationship with tissue specificity remain underexplored. In this study, we conducted integrated proteomic and transcriptomic analyses of EVs derived from six dental stem cells (DSCs) and three systemic stem cells (SSCs) to investigate the role of EVs in tissue-specific molecular transfer. This study found that although DSCs and SSCs share 92.1% of the core proteome, the EVs derived from each stem cell type displayed distinct molecular signatures. EVs from DSCs were enriched in signaling molecules, reflecting their parent cells' roles in local tissue repair, whereas EVs from SSCs carried mitochondrial and metabolic proteins, indicating their preferential involvement in metabolic regulation. Furthermore, we uncovered that the parent cells transferred 83% of the core proteins to their EVs in a tissue-specific pattern, ensuring that dental EVs retain prominent signaling functions. Thus, understanding the relationship between EVs and their parent stem cells with respect to tissue origin would be helpful to harness EVs as targeted therapeutic agents, particularly in oral regenerative medicine.
In tendons, ligaments, and menisci, collagen fibers running the length of the tissue are the primary source of strength and function. Cells assemble these fibers hierarchically from nanometer-wide fibrils into larger fibers and fascicles, increasing in size throughout development and with mechanical loading. These fibers largely do not regenerate after injury or with repair, limiting recovery options. Engineered replacements are a promising treatment option; however, it remains a challenge to produce the hierarchical collagen fibers essential to tissue strength, limiting their applications. To better repair, regenerate, and engineer these tissues, we must better understand how cells regulate hierarchical fiber formation and maintenance. It is well established that mechanical cues are critical for cell-driven hierarchical fiber formation, which cells sense through several mechanisms, such as integrin-mediated adhesions, cell-to-cell connections, mechanosensitive ion channels, primary cilia, and caveolae. These mechanisms of mechanosensation have been well studied at the fibril scale of collagen organization, but as tissues mature, the loading environment becomes more complex, with cells experiencing increasing secondary shear and compressive loads generated by the developing hierarchical structure. Mechanical cues in this environment are likely sensed through several pathways, each likely playing a role in tissue maturation and injury. There remains a clear gap in our understanding of the later stages of hierarchical fiber formation, which are crucial to better understand since large hierarchical fibers dominate the human musculoskeletal system. Here, we review the role of mechanobiology in hierarchical fiber development and maintenance, and highlight what still needs further research to better regenerate fibers in engineered replacements or in vivo after injury. A better understanding of the mechanisms by which cells form hierarchically organized collagen fibers could help to overcome the limitations of current tissue engineering techniques and help to create functional repairs and replacements.
For addressing the challenges regarding muscle injuries, 3D printing has been a promising technique to fabricate patient-specific scaffolds and effectively guide myotube alignment. Although methacrylate-conjugated gelatin (GelMA) is widely used as an ink material for 3D printing because of its facile photo-crosslinking and cell-adhesive properties, its intrinsic low viscosity and weak mechanics require high concentrations of the polymer for 3D printing and matching with tissue-like modulus, while its limited tissue adhesion further restricts its applicability in on-muscle printing. In this study, we propose a printable and bioadhesive hydrogel ink (PBAink) with low polymer concentration of alginate tethered with phenylborate and methacrylate (AlMABA), which exhibits a storage modulus similar to that of muscle tissues and undergoes rapid crosslinking within 90 s under blue light irradiation, making it suitable for 3D printing. Additionally, it exhibits low swelling under physiological conditions and good biocompatibility, owing to its excellent hydrophilic properties imparted by phenylborate groups, making it a suitable material for direct on-muscle printing. Notably, because dynamic bonds between cis-diols and phenylborate groups are formed in phosphate-buffered saline environments, we optimized the salt concentration of the buffer solution mixed with AlMABA to enhance cohesion; this led to the development of PBAink, which enhanced fidelity of printing at low concentrations, while the methacrylate groups ensured structural stability via photo-crosslinking. Moreover, PBAink exhibits tissue-adhesive properties compared with methacrylate-conjugated alginate and GelMA, supporting the direct on-muscle printing and conformal integration of the printed hydrogel with the muscle tissue. The PBAink exhibited intriguing cell-adhesive properties, inducing C2C12 clustering, while also promoting cell spreading. Finally, these features contributed to increased cell density and enhanced F-actin coverage on 3D-printed PBAink scaffolds, thereby highlighting its potential as an effective alternative to conventional GelMA-based inks.
Urethral strictures can cause significant discomfort and progressive urinary tract damage if left untreated. Current reconstructive options, including urethral resection and buccal mucosa grafting, are associated with several limitations such as donor-site morbidity, limited tissue availability, and variable long-term outcomes. To address these challenges, we developed a novel multilayered 3D-bioprinted urethral construct designed to closely mimic the native urethral architecture. Using an Integrated Tissue and Organ Printing System (ITOP) equipped with a rotating mandrel, tubular urethral constructs were fabricated with distinct layers consisting of urothelial cells (UC), basement membrane (BM), smooth muscle cells (SMC), and supportive polycaprolactone (PCL). Autologous UC and SMC isolated from urinary bladder tissue were incorporated into a fibrinogen-based hydrogel bioink. Following in vitro maturation, the constructs were evaluated using viability assays, immunohistochemistry, and biomechanical testing. Live/Dead staining demonstrated an average cell viability of 75% for both UC and SMC populations. Immunostaining confirmed appropriate localization of the different cell types within their respective layers. Tensile testing showed that constructs matured for 14 days developed stable and elastic tissue-like mechanical properties. To further improve construct handling and structural integrity, horizontal reinforcement bands were incorporated into the PCL layer. Using this approach, 4 cm-long and 0.5 cm-diameter urethral constructs with native-like multilayered organization were successfully fabricated. This novel 3D-bioprinting strategy demonstrates strong potential for generating customizable and biologically relevant urethral grafts for future reconstructive applications. Ongoing in vitro optimization and planned in vivo evaluation in a porcine model aim to further validate the structural and functional performance of the construct and support future clinical translation for urethral and other tubular tissue reconstruction.
Given the number of rotator cuff (RC) repairs performed annually and the high rate of structural failure, there remains a significant clinical need for new approaches to augment the repair by enhancing the rate and quality of the tendon healing processes. Tissue-engineering approaches that combine the use of scaffolds and bioactive molecules represent promising new solutions for RC repair. In this study, we investigated the effect of the incorporation of two innate immune pattern recognition receptor agonists (PRRAs) into surgically implanted hydrogels on healing in vitro using ovine RC tendon tissues and in vivo in a translational rat model of RC injury. To address the impact of these innate immune agonists on shoulder healing, we assessed gait function, surgical site histopathology, and quantification of local immune cell infiltrates. We also treated tendon tissues in vitro to assess the impact on tendon transcriptomic responses. We hypothesized that early stimulation of innate immune responses at the site of tendon injury would improve functional and structural tendon healing. We found that of the three PRRAs evaluated, only polyinosine-polycytidylic acid [Poly(I:C)] improved functional gait quality in the postinjury period. However, PRRA injection exerted minimal effects on tendon histology or the density of immune infiltrates. In vitro transcriptomic analysis of tendon blocks treated with PRAAs provided evidence of activation of interferon pathways by Poly(I:C)-treated tissues, suggesting a role of these innate immune cytokines in the pain reduction response. Thus, we conclude that incorporation of certain PRRAs in hydrogels may improve functional recovery after shoulder tendon repair surgery, but also recognize that the timing and release kinetics of agonists delivered in gels at the surgery site can be further optimized. Impact Statement The immunological cascade of healing rotator cuff tissue is a large determinant of whether the tissue will heal or scar. Immunomodulation through biologics has shown mixed success in clinical applications for rotator cuff repair, perpetuating high retear rates. As such, there is a need to investigate novel, immunologically instructive therapies. Herein, we demonstrate that incorporating Toll-like receptor 3 agonist, polyinosine-polycytidylic acid, into a methylcellulose/hyaluronic acid blend hydrogel can induce functional, but interestingly, not tissue, level changes in a rat model of rotator cuff damage. Indicating initial efficacy for a novel potential immunotherapy for rotator cuff injury.
Glioblastoma (GBM) tumors are characterized by an excess of extracellular glutamate, one important source of which is the tumor cells themselves. This abundance of glutamate promotes GBM proliferation, migration, and therapeutic resistance, and causes excitotoxicity in nearby neurons. However, despite glutamate's clear role in promoting GBM aggression, the exact mechanisms through which excess glutamate drives these phenotypes, particularly three-dimensional (3D) invasion, remain incompletely understood. To address this gap, we used a 3D brain-mimetic hyaluronic acid (HA) hydrogel to investigate the role of glutamate signaling in GBM 3D invasion. We demonstrate that inhibiting the glutamate N-methyl-d-aspartate receptor (NMDAR) reduces invasion from 3D tumorspheres, a result that is reproducible across multiple continuous culture models and a patient-derived xenograft cell line. We then conducted glutamate-driven invasion studies in 3D HA-based devices that can be microdissected to isolate and differentially analyze invasive and noninvasive cells. Transcriptomic analysis of invasive, noninvasive, and drug-treated populations of cells reveals that NMDAR inhibition suppresses several pathways associated with the mechanobiology of invasion, including matrix remodeling and collagen deposition. Correspondingly, supplementation with exogenous collagen VI partially rescued 3D invasion. Our work speaks to the potential value of biomaterial platforms for identifying the autocrine and paracrine mechanisms through which neurotransmitters fuel GBM invasion.Impact StatementGlutamate is an abundant signaling molecule in the glioblastoma (GBM) microenvironment and important driver of disease progression; however, the mechanisms through which glutamate promotes invasion in three-dimensional (3D) environments remain poorly understood. By combining engineered hyaluronic acid hydrogel platforms and transcriptomic analysis, we determine that blocking glutamate signaling through the N-methyl-d-aspartate receptor suppresses invasion in 3D by interfering with extracellular matrix remodeling processes. This work highlights the utility of biomaterial platforms in dissecting neurotransmitter signaling in GBM invasion.
Periodontal ligament (PDL) is a thin connective tissue that connects the tooth to the bony socket and plays a crucial role in the regeneration and maintenance of homeostasis of periodontal tissues by supplying stem/progenitor cells. Induced pluripotent stem cells (iPSCs) are highly anticipated in regenerative medicine because of their differentiation potential into a wide variety of cell types. In this study, we investigated the effects of humoral factors on iPSC differentiation by culturing iPSCs in the presence of PDL cell-derived culture supernatants. Changes in gene expression were analyzed using quantitative real-time PCR, reverse-transcription PCR, and RNA sequencing. The marker protein expression on the cell surface was assessed using flow cytometry. Periodontal regeneration was verified by microcomputed tomography and histomorphological observation in a periodontal defect model using male F344/NJcl-rnu/rnu rats. When iPSCs were cultured in the PDL culture supernatant, some cells formed clumps, and spindle-shaped cells grew out from them. Upon passaging, spindle cells increased further, and by the fifth passage, these cells occupied the entire culture. These cells (iPS-PDLs) expressed genes such as periostin and Asporin/PLAP1, and their comprehensive gene expression patterns resembled those of PDL cells. iPS-PDL cells exhibited a cell surface antigen profile of CD90+, CD73+, CD105+, CD44+, CD29+, CD14-, CD34-, CD45-, and CD19- and differentiation potential into osteoblasts, adipocytes, and chondrocytes. Transplantation of iPS-PDLs into rat periodontal defects increased the height of newly formed bone and enhanced periodontal tissue regeneration after 4 weeks. Our results showed that iPSCs differentiated into cells with properties similar to those of PDL cells in the presence of humoral factors of cultured PDL cells. Additionally, the transplantation of iPS-PDL cells into periodontal defects induces periodontal tissue regeneration. These findings provide valuable insights for developing novel periodontal regenerative therapies using iPSCs.
Critical-sized bone defects remain a significant clinical challenge, as their size prevents spontaneous healing and necessitates surgical intervention. Although autografts are considered the clinical gold standard, their use is limited by donor site morbidity and tissue availability, while allografts carry risks of disease transmission and long-term failure. In this study, we developed a composite polymer ink for high-resolution digital light processing (DLP) 3D printing of bone tissue engineering scaffolds intended for load-bearing applications. A combination of poly(propylene fumarate) (PPF), poly(caprolactone fumarate) (PCLF), and hydroxyapatite (HA) was formulated to achieve tunable mechanical properties and controlled scaffold architecture. Scaffolds with varying porosities and material compositions were fabricated and evaluated using compressive mechanical testing and finite element modeling to assess structural integrity and stress distributions. In vitro studies using preosteoblast cells demonstrated consistently high cell viability (>75%) across all scaffold designs, with sustained proliferation over 7 days. Notably, scaffold porosity and material composition influenced proliferative responses, with significant increases observed in select formulations. Collectively, these results demonstrate that DLP-printed PPF/PCLF/HA composite scaffolds provide a mechanically viable and cytocompatible platform with tunable properties, supporting their potential utility in bone tissue engineering applications.Impact StatementCritical-sized bone defects lack effective, widely accessible treatment options due to the limitations of current grafting strategies. This work introduces a digitally light processed (DLP) 3D-printable composite scaffold with tunable mechanical properties and architecture suitable for load-bearing applications. By integrating poly(propylene fumarate), poly(caprolactone fumarate), and hydroxyapatite, the platform enables control over structural and biological performance while maintaining high cytocompatibility. These findings highlight a scalable and customizable approach to bone tissue engineering that may reduce reliance on traditional grafts and improve outcomes in complex bone repair.
Micronized collagen-based bioscaffolds are increasingly used in clinical applications for wound repair and soft tissue regeneration. This study compared the structural properties of four different commercially available micronized products derived from either reconstituted collagen (pRC), urinary bladder matrix (pUBM), or ovine forestomach matrix (mOFM, mOFMµ). The test articles were characterized by laser diffraction analysis, scanning electron microscopy (SEM), micro-computed tomography (micro-CT), packing density, differential scanning calorimetry, rheometry, proteolytic stability, agarose gel electrophoresis, and blood clotting index. Particle size and surface morphology, assessed by laser diffraction, SEM, and micro-CT, revealed marked differences in particle size, shape, and aggregation. Packing density ranged from 80.3 ± 2.7 mg/cm3 (mOFM) to 484.7 ± 17.8 mg/cm3 (pRC). Thermal analysis demonstrated the native structure of the OFM-based test articles (Tm, 59.80 ± 0.11°C and 58.15 ± 0.15°C) relative to pUBM and pRC (Tm, 41.06 ± 0.06°C and 40.59 ± 0.23°C). Rheological testing revealed that mOFM and mOFMµ had increased cohesive energy, indicating better mechanical resilience when the micronized materials were rehydrated to form a paste. The OFM-based test articles exhibited the greatest resistance to proteolytic digestion (T1/2, 12.730 ± 1.232 and 5.759 ± 0.1296). All the test articles, except for the reconstituted collagen product, demonstrated hemostasis in whole blood. Micronized reconstituted collagen showed immediate dissolution and no fluid absorption, hemostasis, or resistance to proteolytic digestion, whereas micronized OFM showed the greatest proteolytic stability and packing density. Substantial differences among the micronized bioscaffolds were revealed from the analysis, most likely due to their different source materials and manufacturing processes. Careful consideration of these parameters is warranted when selecting a micronized product for soft tissue applications.