The distinctive milieu of the bone marrow (BM), known as the BM niche, supports hematopoietic stem cells (HSCs) and serves as a foundation for hematopoietic regeneration. Myeloablative stress disrupts not only hematopoietic stem and progenitor cells but also essential BM niche components, including endothelial cells (ECs) and mesenchymal stromal cells (MSCs); disruption of the latter impairs efficient hematopoietic recovery. However, therapeutic strategies targeting niche restoration remain largely underdeveloped. Here, we demonstrate that the Hippo pathway effectors YAP/TAZ are critical for enabling ECs and MSCs to respond to BM injury, and that YAP/TAZ activation accelerates BM niche recovery, thereby promoting hematopoietic regeneration. We found that YAP/TAZ are rapidly activated in both MSCs and ECs following myeloablative stress, maintaining MSC multipotency and orchestrating vascular remodeling. Mechanistically, YAP/TAZ function as transcriptional hubs in MSCs, regulating key transcriptional factors such as Ebf1 and Ebf3. This regulation preserves MSC identity by preventing osteogenic and fibrogenic differentiation while promoting the expression of hematopoietic factors such as Cxcl12 and angiogenic factors. In addition, YAP/TAZ signaling in MSCs and ECs appeared to coordinately remodel sinusoidal vessels following BM injury. These YAP/TAZ-mediated niche responses are essential for HSC retention and hematopoietic regeneration following diverse myelosuppressive therapies. Notably, pharmacological activation of YAP/TAZ enhances BM niche reorganization and augments hematopoietic regeneration following myeloablative therapies. These findings establish YAP/TAZ as central regulators of BM niche resilience, providing a rationale for niche-targeted therapeutic strategies to enhance hematopoietic regeneration.
Tail regeneration in lizards occurs after formation of a wound (regenerating) epidermis that surrounds and protects the inner mass of mesenchymal-like cells of regenerating blastema formed in highly hydrated conditions. Aside mechanical protection, enrichment of lipids mixed with Intermediate Filament Keratins (IFKs) is essential for maintaining the blastema alive to form a regenerated tail. After tail amputation in the wall lizard Podarcis muralis, a regenerating wound epidermis is formed which keratinocytes accumulate lipids among IFKs during their differentiation into corneocytes. The present mass spectrometric study characterizes in details the different lipids produced in normal and regenerating tail epidermis of this reptile. Among the classes of lipids that undergo to significative variations are included cholesterol esters and hexosylceramides that increase in comparison to the normal, non-regenerating epidermis. Among other lipid classes, also lysophospholipids, phosphoglycerids and cardiolipins undergo a significant increment in wound keratinocytes, probably related to cell membrane turnover during keratinocyte regeneration. In contrast, in wound keratinocytes triglycerides decrease in comparison to those of normal epidermis. Other classes of lipids do not differ significantly between normal and regenerating epidermis, indicating minor roles for the formation of a water-loss barrier. We suggest that the marked changes in lipid profile due to the increase in cholesteroyl-esters and hexosylceramides in parallel with the triacylglycerols decrease, are correlated with the establishment of a more effective barrier against water loss in the lizard epidermis. The evolution of an efficient barrier to water-loss was essential, in addition to specific gene developmental pathways, for tail regeneration in lizards.
Local injections such as bupivacaine are used to treat strabismus, although the mechanism of its clinical effects is unknown. The purpose of this study is to analyze the effects of bupivacaine on extraocular muscle regeneration in a preclinical model. Laboratory study. Three-month-old male New Zealand white rabbits with age- and sex-matched saline injection controls and uninjected controls. One superior rectus muscle per animal was injected with either 3% bupivacaine or saline control and harvested at 1 week, 1 month, or 3 months after treatment. Histomorphometric analysis was used to determine the effects of bupivacaine on extraocular muscles. Data were analyzed for the global and orbital layer separately, as well as the entire muscle cross-sectional area. Muscle morphology, markers of muscle regeneration, muscle size. Treatment with 3% bupivacaine had a myodestructive effect on the injected extraocular muscle, with disruption of myofiber organization and areas of missing myofibers. However, even 1 week after injection, we observed significantly more embryonic myosin heavy chain-positive myofibers, indicating newly regenerated myofibers, in the bupivacaine group compared with the saline group. Embryonic myosin heavy chain was still significantly expressed at 1 month after bupivacaine injection in extraocular muscles, in stark contrast to skeletal muscles elsewhere in the body where embryonic myosin heavy chain expression decreases 1 to 2 weeks after injury. There was a significant increase in the density of muscle stem cells and myofibers with centralized nuclei 3 months after bupivacaine injection compared with saline in both the orbital and global layers. Muscle size and extracellular matrix components were not increased at 3 months after bupivacaine injection compared with saline. Bupivacaine's effects on extraocular muscles may be explained in part by bupivacaine triggering a regenerative response, initially forming new myofibers and increasing the number of muscle stem cells to exert its effects as a treatment for strabismus. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
The regeneration of vascularized bone tissue requires biomaterials that deliver coordinated osteogenic and angiogenic signals within mechanically robust three-dimensional architectures. Here, we present a decellularized osteo-angiogenic scaffold generated by integrating mineral-coated nanofiber-incorporated human adipose-derived stem cell spheroids into a 3D-printed polymer scaffold. The mineral-coated spheroids enhanced extracellular matrix (ECM) deposition and osteogenic priming during preculture, and subsequent decellularization efficiently removed cellular components while preserving osteoinductive matrix proteins and pro-angiogenic growth factors. The resulting cell-free scaffold established a homogeneous, multifunctional signaling microenvironment that supported host cell infiltration and potently induced coupled osteogenic and angiogenic responses in vitro without exogenous growth factor supplementation. In a murine critical-sized calvarial defect model, the mineralized scaffold achieved significantly enhanced neovascularization (16 ± 1 α-SMA+ arterioles per mm2) and mature lamellar bone formation (66.2 ± 5.9% BV/TV) compared with the non-mineralized controls. This work introduces a stem cell-derived, ECM-enriched 3D scaffold platform that couples osteogenesis and angiogenesis through endogenous bioactive cues, providing a clinical translation strategy for vascularized bone regeneration.
Guided bone regeneration relies on biomaterials that support bone formation while modulating the healing environment; however, materials with similar indications may exhibit different biological behaviors over time. This study compared the performance of two bovine-derived bone substitutes containing collagen using a rat calvarial critical-size defect model. Fifty-four Wistar rats were allocated to three groups: blood clot (control), Bio-Oss Collagen®, and Extra Graft XG13®. Standardized 5-mm defects were created and treated under guided bone regeneration conditions using a resorbable collagen membrane. Animals were euthanized at 7, 14, and 28 days. Mineralized tissue formation and microarchitecture were assessed by micro-CT, while histological, histomorphometric, inflammatory, angiogenic, and collagen organization analyses were performed to characterize the healing process. Both biomaterials supported tissue formation within the defect compared to the control. Extra Graft XG13® was associated with higher mineralized tissue volume and volume fraction at 14 and 28 days, with more favorable micro-CT-derived microarchitectural parameters and reduced porosity. Early inflammatory and angiogenic responses were comparable between biomaterials, yet defects treated with Extra Graft XG13® exhibited greater new bone formation over time. A reduction in mineralized tissue volume from 14 to 28 days in this group, accompanied by increased collagen organization, may suggest a possible transition toward remodeling; however, this interpretation should be considered with caution due to the absence of direct remodeling markers. In contrast, Bio-Oss Collagen® showed a more gradual pattern of tissue formation and delayed collagen maturation. Overall, Extra Graft XG13® was associated with greater mineralized tissue formation and a higher proportion of organized collagen fibers at later time points, indicating differences in the progression of mineralized tissue formation and matrix organization over time compared to Bio-Oss Collagen®. These findings should be interpreted within the limitations of the experimental model.
Oral cancer is a significant global health challenge, ranking as the sixth most prevalent cancer worldwide, with approximately 377,000 new cases diagnosed annually. The high morbidity and mortality rates are largely attributed to tobacco and alcohol use. While conventional treatments such as surgery, radiation, and chemotherapy have improved survival rates, they often lead to unfavourable aesthetic and functional outcomes. Tissue engineering offers a promising alternative, providing regenerative solutions aimed at restoring both oral function and appearance. By integrating biomaterials, biological systems, and engineering principles, tissue engineering enables the creation of functional tissue replacements. The current review examines different t pathways the potential applications of autologous tissue, oral cancer cell lines, CRISPR, gene-editing technologies, and epigenetic modifications for tissue regeneration. Advanced scaffold technologies that mimic the natural extracellular matrix, along with stem cell-based therapies and bioactive molecules, are employed to support tissue growth and differentiation. Mesenchymal stem cells (MSCs) and induced pluripotent stem cells (iPSCs) show significant potential in regenerating hard and soft oral tissues, while also targeting cancer stem cells (CSCs) to prevent recurrence. Furthermore, innovative technologies like 3D bio printing, combined with vascularization strategies, hold promise for developing patient-specific tissue constructs for reconstructive procedures. In conclusion, tissue engineering offers transformative potential for oral cancer treatment, presenting regenerative therapies that can significantly enhance patient outcomes and quality of life.
Large-scale bone defects resulting from trauma, infection, or tumor resection pose a formidable clinical challenge, with traditional grafting approaches limited by donor availability and potential immune complications. While synthetic biomaterials offer alternatives, their clinical efficacy critically depends on their interactions with the host immune system, particularly macrophages. This review explores the emerging paradigm of "immuno-smart" 3D-printed scaffolds that harness macrophage plasticity to enhance bone regeneration. Analysis is focused on the mechanisms by which macrophages orchestrate the transition from inflammation to healing via dynamic M1-to-M2 polarization, thereby directly influencing osteogenesis, angiogenesis, and tissue remodeling. Current evidence indicates that 3D-printed scaffolds can be engineered to modulate macrophage behavior through multiple strategies: controlled release of bioactive ions (e.g., Mg²⁺, Sr²⁺, and Cu²⁺), incorporation of immunomodulatory molecules, optimization of physical properties such as piezoelectricity, photothermal responsiveness, and precise architectural design. These approaches, which regulate the macrophage-mesenchymal stem cell axis to create pro-regenerative microenvironments, are critically evaluated. Despite promising preclinical outcomes, clinical translation remains challenging due to an incomplete understanding of spatiotemporal immune dynamics, insufficient long-term safety data, and a lack of standardized evaluation protocols. Ultimately, this review provides a comprehensive framework for developing next-generation immunomodulatory bone scaffolds, highlighting the integration of materials science, immunology, and regenerative medicine. We conclude that personalized, closed-loop systems capable of real-time immune modulation represent the future of bone tissue engineering, marking a shift from passive structural support to active biological orchestration.
Wound healing involves a cascade of four overlapping phases-hemostasis, inflammation, proliferation, and remodeling-that demand temporally coordinated intervention. However, most current hemostatic materials merely target the initial hemostatic stage and frequently impair physiological blood clotting, an essential endogenous platform for subsequent tissue regeneration. Herein, we report a novel powder hemostatic material that synergizes with endogenous clotting to orchestrate a continuous hemostasis-to-regeneration cascade. The powder consists of a lipoic acid-sodium lipoate copolymer (PolyLA-LANa) and quaternized chitosan (QCS). Upon contact with blood, this powder rapidly absorbs fluid and forms an adhesive hydrogel in situ via electrostatic and hydrogen bonding. The material concentrates platelets and coagulation factors to form a stable "material-clot" composite. This composite effectively seals wound sites and acts as a functional reservoir for the sustained release of LA-derived bioactive molecules. In rat and rabbit models (liver, femoral artery, muscle/vessel injury), the powder achieves rapid hemostasis with significantly reduced blood loss. In a challenging rat tooth extraction socket model, it stabilizes the clot, prevents dry socket formation, and promotes alveolar bone preservation and soft tissue healing. This "clotting-synergistic" strategy transforms passive hemostats into active regenerative platforms for complex bleeding wounds.
Acute liver failure (ALF) is characterised by massive hepatocyte death and compromised regenerative capacity, yet the metabolic-immune crosstalk underlying these pathological processes remains poorly understood. Here, we demonstrate that lactate acts as a pivotal signal that triggers neutrophil extracellular traps (NETs) formation and release. Integrated RNA-seq and scRNA-seq analyses revealed profound glycolytic reprogramming in Kupffer cells (KCs) during ALF, leading to lactate accumulation within the hepatic microenvironment. Mechanistically, neutrophils import exogenous lactate into mitochondria via monocarboxylate transporter 1 (MCT1), which subsequently activates NETosis. Macrophage depletion or administration of an MCT1 inhibitor reduced NETs formation and ameliorated liver injury. Furthermore, we demonstrate that hepatocytes internalise NETs DNA, which is sensed by endosomal Toll-like receptor 9 (TLR9). Activation of the TLR9 signalling pathway suppresses the expression of Krüppel-like factor 15 (KLF15). This downregulation diminishes AJUBA and disrupts the KLF15-AJUBA interaction, thereby increasing the phosphorylation of YAP1 and impeding hepatocyte proliferation. Notably, KLF15 overexpression bypassed TLR9-mediated inhibitory signals and rescued the NETs-induced regenerative failure in vitro. In conclusion, our study elucidates a novel KCs-neutrophil-hepatocyte crosstalk wherein lactate-driven NETosis thwarts liver regeneration via the TLR9/KLF15/AJUBA axis, thereby identifying potential therapeutic targets for the clinical management of ALF.
Intervertebral disc degeneration (IVDD) is a leading cause of chronic back pain and long-term disability, imposing a substantial burden on healthcare systems worldwide. At the core of this degenerative process lies oxidative stress, a pathological condition driven by excessive accumulation of reactive oxygen species (ROS). This redox imbalance initiates a destructive cascade within the intervertebral disc, resulting in injury, premature senescence, and death of nucleus pulposus cells. The loss of these critical cells subsequently provokes inflammatory responses and degradation of the extracellular matrix, ultimately compromising the structural integrity of the disc. Although conventional clinical interventions effectively alleviate symptoms, they typically fail to target the underlying biological mechanisms or halt disease progression. This unmet therapeutic need has spurred growing interest in antioxidant materials, which offer a more proactive approach by directly neutralizing ROS and restoring redox homeostasis. Beyond mere ROS scavenging, these materials also mitigate inflammation and foster a microenvironment supportive of tissue regeneration. Current research efforts are increasingly focused on the rational design of such antioxidant systems, particularly their integration with advanced cell-based therapies to enhance regenerative outcomes. A detailed assessment of how these materials modulate specific pathological pathways is essential to clarify their practical utility and inherent limitations. Translating promising laboratory results into clinical practice remains a major challenge, necessitating rigorous evaluation of their performance in complex biological settings. Refining these antioxidant strategies may ultimately pave the way for a paradigm shift, from symptomatic relief to genuine functional restoration in patients with IVDD.
The accumulation of root-exuded berberine (BER) in soil is a key contributor to continuous cropping obstacles, threatening sustainable agriculture. In this study, a novel biochar-montmorillonite composite was synthesized via co-ball milling using traditional Chinese medicine residue derived biochar and montmorillonite (Mt) for berberine removal. The composite exhibited superior adsorption performance with a maximum capacity of 231.60 mg·g-1. Characterization by Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy revealed that co-ball milling created an intimate hybrid structure with enhanced surface area and abundant functional groups. Adsorption kinetics followed a pseudo-second-order model governed by intraparticle diffusion, while isotherms were well-described by Langmuir, Freundlich, and Temkin models. Thermodynamic analysis indicated spontaneous and endothermic adsorption. The optimal pH range for berberine (BER) adsorption onto the BMC-Mt10% composite was 5-7. Relatively low concentrations of dissolved HA (≤10 mg) can enhance the adsorption capacity for BER, and the composite maintained 76.99% of its initial adsorption capacity after five consecutive regeneration cycles. Mechanistic studies elucidated that the adsorption involved multifaceted interactions, including pore filling, hydrogen bonding, π-π stacking, cation exchange, and electrostatic attraction. These findings demonstrate that biochar-montmorillonite composites are promising materials for mitigating berberine-induced continuous cropping obstacles in agricultural soils.
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Meristems are the growth centers of plants and fundamental in understanding plant development, morphogenesis, and vegetative propagation. Across all plant groups, the phytohormone auxin controls meristem maintenance, represses the emergence of new meristems (apical dominance), and mediates cellular reprogramming when new meristems regenerate following removal of existing meristems. The liverwort Marchantia produces clonal propagules (gemmae) featuring two apical notches that develop into functional meristems. This presents a tractable experimental system to study meristem developmental biology. I used laser ablation microscopy to precisely disrupt cells in and around the developing premeristem in the apical notches of germinating gemma, finding that the first cell row is indispensable. Within this layer, a contiguous quorum of stem cells is required for activity. Apical notches reorientate in response to damage, demonstrating that the apical notch stem cells act as a communicating population. Feedback from the stem cell population is necessary to maintain notch activity and generate the notch apex. These experiments show communication between notches and regenerating meristems. The apical dominance signal represses cell division and requires both sources and sinks, features of auxin-mediated communication. Central regions of the gemma could transmit these apical dominance signals, but the tissues of the gemma periphery could not. I present a model of Marchantia gemma and apical notch organization, involving intra-, inter-, and extranotch communication. This provides a framework for further study of meristem formation, communication, and maintenance in Marchantia and improving knowledge of plant meristems more generally.
Osteoporosis (OP) is a gradual metabolic bone disease characterized by decreased bone mass and degradation of bone microarchitecture. It affects hundreds of millions of people globally and places considerable pressure on healthcare systems. Current pharmacological treatments, such as bisphosphonates, selective estrogen receptor modulators, and anabolic agents, can reduce fracture risk; however, their prolonged use is limited by significant adverse effects, elevated treatment costs, and a lack of sustained disease remission. Their constraints have intensified interest in restorative approaches utilizing mesenchymal stem cells (MSCs). In the past 20 years, MSCs have emerged as attractive treatment options for OP due to their capacity to differentiate into osteoblasts, modulate immune responses, and exert paracrine effects. Bone marrow-MSCs are the best characterized; nevertheless, MSCs obtained from adipose tissue, umbilical cord, and dental pulp have distinct benefits. Preclinical data demonstrate that direct MSC transplantation enhances bone mineral density, promotes osteoblast production, and reestablishes the equilibrium of bone remodeling in many OP models, including Ovariectomy, glucocorticoid-induced OP, and diabetic OP. Nonetheless, significant obstacles persist: insufficient targeting of osteoporotic bone surfaces, suboptimal cell viability and integration, donor heterogeneity, and unresolved safety concerns. The discovery that the secretome and exosomes (EXOs) produced from MSCs recapitulate several therapeutic advantages of the original cells has initiated a transition toward cell-free methodologies. EXOs produced from MSCs include osteogenic microRNAs (including miR-150-3p and miR-21), inhibit NLRP3 inflammasome activation in osteoclasts, promote macrophage polarization toward an M2 phenotype via TRIM25/TREM1 signaling, and facilitate angiogenesis through the activation of the PI3K/Akt pathway. Furthermore, nanoparticle engineering and combinatorial medicines are advancing to enhance targeting and therapeutic efficacy.
Many plant species can propagate asexually or be regenerated in vitro; but asexual offspring are more likely to maintain environmentally induced epigenetic marks, for instance, inheritance of the prolonged cold-induced 'vernalized state' in overwintering plants through asexual reproduction. Here we demonstrate that 'vernalized state' is reprogrammed during Arabidopsis asexual propagation through somatic embryogenesis. This overturns a long-standing idea, that the vernalized state could not be reset through asexual reproduction, and provides a strategy to erase parental effects on offspring during asexual reproduction.
[This corrects the article DOI: 10.1016/j.mtbio.2025.102324.].
Tooth extraction is a fundamental dental intervention for managing oral infections; however, the resulting tooth loss is associated with systemic health risks, including cognitive decline and increased mortality. Alveolar bone resorption following tooth extraction significantly alters jaw morphology, complicating subsequent functional rehabilitation. Despite its clinical significance, the cellular and molecular mechanisms governing bone regeneration within extraction sockets remain poorly understood. Here, we identified group 2 innate lymphoid cells (ILC2s) as pivotal regulators of alveolar bone regeneration following tooth extraction. Using single-cell RNA sequencing and flow cytometry, we demonstrated that ILC2s accumulate and persist within extraction sockets beyond the acute inflammatory phase. Genetic lymphocyte ablation revealed that loss of all ILCs severely impairs bone formation, highlighting their essential role in socket regeneration. Following tooth extraction, ILC2s exhibited increased interleukin (IL)-13 production and promoted bone formation via IL-13-mediated activation of bone marrow-derived mesenchymal stromal cells. Single-cell RNA sequencing and histological analyses suggested that gingival fibroblasts are a major source of IL-33 in extraction sockets during mucosal healing. IL-33 activated ILC2s, increasing IL-13 production and promoting osteogenesis, whereas IL-33 neutralization suppressed ILC2 activation and impaired socket bone regeneration. Collectively, these findings suggest that the gingival fibroblast-IL-33-ILC2-IL-13 axis may contribute to the regulation of alveolar bone regeneration following tooth extraction. This study provides a biological basis for developing novel therapeutic strategies to optimize postextraction bone preservation.
One of the key factors for hard tissue regeneration is to develop mineralized fibrous scaffolds. These scaffolds can provide a micro-environment resembling the structure and mechanical properties of the extracellular matrix (ECM) of hard tissues favorable for subsequent cell responses and tissue regeneration. During biomineralization, amorphous precursor phases of calcium phosphate infiltrate into preformed collagen fibrils, and upon crystallization, the collagen fibrils are embedded with oriented hydroxyapatite (HA) nanocrystals. We previously demonstrated that hydrogels made of elastin-like recombinamers (ELRs) can template mineralization where minerals were selectively deposited into their frameworks. In this work, we focus on mimicking the nanostructure of the mineralized tissues, namely the intra- and extrafibrillar mineralized collagen fibrils, using the synthetic ELRs. We first electrospun the ELRs into nanofibers and then biomimetically mineralized them via the polymer-induced liquid-precursor (PILP) process. We tested two different ELRs one with a peptide sequence derived from the salivary protein statherin (st-ELR) and a reference one lacking the statherin sequence (ref-ELR). X-ray diffractometry (XRD) and Energy-dispersive X-Ray Spectroscopy (EDS) verified the mineral phase in the ELR nanofibers was HA. Scanning and Transmission Electorn Microscopy (SEM and TEM) analyses revealed that HA nanocrystals were infiltrated into and randomly oriented within the ELR nanofibers. The elastic modulus and hardness of the mineralized ELR nanofibers was increased significantly compared to unmineralized ELR. The mineralized nanofibers promoted the proliferation and osteogenic differentiation of pre-osteoblasts. These results support that a scaffold obtained using this biomimetic strategy and made of mineralized ELR electrospun nanofibers with controlled mineralization and improved mechanical properties has great potential for being used in hard tissue regeneration, such as craniofacial and periodontal and perimplant regeneration as well as tertiary dentin regeneration, as it mimics the structure and mechanical properties of collagen-HA nanocomposites.
Articular cartilage repair remains a major clinical challenge. Although microfracture (MF) is widely applied, it frequently results in fibrocartilaginous repair with limited mechanical durability and unsatisfactory long-term outcomes. The persistent inflammatory microenvironment following cartilage injury disrupts tissue homeostasis and impairs chondrogenic differentiation of bone marrow stem cells (BMSCs), representing a major impediment to regeneration. Here, an injectable, thermosensitive composite hydrogel, constructed from a dopamine-modified hyaluronic acid and Pluronic F127 network, which incorporates chlorogenic acid (CA) and ZIF-8 nanoparticles encapsulated with kartogenin (KGN), is developed to establish a cascade repair strategy. Preferential release of CA can efficiently reprogram macrophages toward a pro-regenerative M2 phenotype and improve anti-inflammatory cytokine secretion, thereby creating a pro-regeneration microenvironment. Subsequently, the sustained release of KGN further stimulates BMSCs chondrogenic differentiation within this optimized niche. Biological assays demonstrate that this synergistic mechanism enhances cartilage-specific matrix synthesis and alleviates matrix degradation under inflammatory conditions. Furthermore, this composite hydrogel, combined with MF, improves cartilage tissue regeneration in a rat model, as evidenced by smooth defect filling, well-organized extracellular matrix deposition, and reduced Matrix metalloproteinase 13-mediated degradation. This work presents a synergistic immuno-chondroregenerative platform that overcomes fundamental limitations of MF and offers a promising paradigm for functional cartilage regeneration.
The transition to green energy depends on the effective conversion of lignocellulosic biomass into a high-quality fossil-feedstock-compatible bio-oil, and catalytic pyrolysis is a promising approach. Here, we present a new design of a radial-axial fixed-bed ex-situ catalytic pyrolysis system to address the common issue of excessive pressure buildup in traditional fixed-bed reactors. This system includes a radial-flow pyrolysis reactor and an axial-flow catalytic pyrolysis-vapor upgrading reactor, thereby enabling the study of reaction parameters, mass balances, and three-phase product properties in ex-situ catalytic pyrolysis of biomass, as well as the stability and regenerability of the catalyst. As a demonstration, ex-situ catalytic pyrolysis of pinewood using Na2CO3/γ-Al2O3 catalyst was performed at 500 °C at different biomass-to-catalyst (B/C) ratios (of 2-16), and multiple reaction-regeneration cycles were conducted. Catalytic pyrolysis bio-oil at a B/C ratio of 2 exhibited high quality, with an oxygen content of 16.1 wt% and an HHV of 34.0 MJ kg-1 over the fresh catalyst. However, it degraded during reaction-regeneration cycles, showing an oxygen content of 27.0 wt% and an HHV of 27.8 MJ kg-1 over the 4th-time-regenerated catalyst. Comprehensive characterization revealed both reversible catalyst deactivation (due to coke deposition) and irreversible catalyst deactivation (related to the transformation of the active sites to NaAlO2). This work emphasizes the development of novel catalysts with good stability and regenerability under harsh catalytic pyrolysis and regeneration conditions, and this new radial-axial fixed-bed ex-situ catalytic pyrolysis system provides an alternative reactor option.