Biomimetic multi-channel nerve conduits with micro/nanostructures for rapid nerve repair.

Peripheral nervous system (PNS) injuries often lead to significant sensory and motor impairments. Traditional artificial nerve conduits, lacking anisotropic structures, have been associated with prolonged repair time and failures in nerve regeneration. This study aimed to address these challenges by developing a novel approach for rapid repair of peripheral nerve injuries (PNI). A 3D oriented fibers scaffold featuring distinct radial (RFs) and longitudinal (LFs) fibers orientations was engineered using coaxial electrospinning and gas directional foaming techniques. This scaffold was then integrated with a shape memory conduit to form a directional multi-channel nerve conduit with micro/nanostructures. The results revealed that the grooved surface of the fibers significantly improved cellular directional guidance, effectively facilitating the migration of SCs from the periphery towards the center and from the base to the apex of the scaffold. In a rat model with a 10 mm nerve defect, the ND-PLATMC/LF ND-PCL scaffold significantly enhanced nerve regeneration and motor function recovery within 4 weeks. These results suggest the potential of this innovative scaffold for efficient repair of the nerve injuries.

Amphiphilic cytokine traps remodel marrow adipose tissue for hematopoietic microenvironment amelioration.

Hematopoietic stem cell transplantation (HSCT) is extensively employed in the treatment of hematological malignancies but is markedly constrained by the paucity of hematopoietic stem/progenitor cells (HSPCs). Recent studies have found that marrow adipose tissue (MAT) acts on hematopoiesis through complicated mechanisms. Therefore, the osteo-organoids fabricated in vivo using biomaterials loaded with recombinant human bone morphogenetic protein 2 (rhBMP-2) have been used as models of MAT for our research. To obtain sufficient amounts of therapeutic HSPCs and healthy MAT, we have developed amphiphilic chitosan (AC)-gelatin as carriers of rhBMP-2 to the regulate type conversion of adipose tissue and trap hematopoietic growth factors. Unlike medicine interventions or cell therapies, the traps based on AC not only attenuate the occupancy of adipocytes within the hematopoietic microenvironment while preserving stem cell factor concentrations, but also improve marrow metabolism by promoting MAT browning. In conclusion, this approach increases the proportion of HSPCs in osteo-organoids, and optimizes the composition and metabolic status of MAT. These findings furnish an experimental basis for regulating hematopoiesis in vivo through materials that promote the development of autologous HSPCs. Additionally, this approach presents a theoretical model of rapid adipogenesis for the study of adipose-related pathologies and potential pharmacological targets.

The Effect of Aligned and Random Electrospun Fibers Derived from Porcine Decellularized ECM on Mesenchymal Stem Cell-Based Treatments for Spinal Cord Injury.

The impact of traumatic spinal cord injury (SCI) can be extremely devastating, as it often results in the disruption of neural tissues, impeding the regenerative capacity of the central nervous system. However, recent research has demonstrated that mesenchymal stem cells (MSCs) possess the capacity for multi-differentiation and have a proven track record of safety in clinical applications, thus rendering them effective in facilitating the repair of spinal cord injuries. It is urgent to develop an aligned scaffold that can effectively load MSCs for promoting cell aligned proliferation and differentiation. In this study, we prepared an aligned nanofiber scaffold using the porcine decellularized spinal cord matrix (DSC) to induce MSCs differentiation for spinal cord injury. The decellularization method removed 87% of the immune components while retaining crucial proteins in DSC. The electrospinning technique was employed to fabricate an aligned nanofiber scaffold possessing biocompatibility and a diameter of 720 nm. In in vitro and in vivo experiments, the aligned nanofiber scaffold induces the aligned growth of MSCs and promotes their differentiation into neurons, leading to tissue regeneration and nerve repair after spinal cord injury. The approach exhibits promising potential for the future development of nerve regeneration scaffolds for spinal cord injury treatment.

Calcium Ion-Coupled Polyphosphates with Different Degrees of Polymerization for Bleeding Control.

The development of efficient hemostatic materials is crucial for achieving rapid hemorrhage control and effective wound healing. Inorganic polyphosphate (polyP) is recognized as an effective modulator of the blood coagulation process. However, the specific effect of polyP chain length on coagulation is not yet fully understood. Furthermore, calcium ions (Ca2+) are essential for the coagulation process, promoting multiple enzyme-catalyzed reactions within the coagulation cascade. Hence, calcium ion-coupled polyphosphate powders with three different degrees of polymerization (CaPP-n, n = 20, 50, and 1500) are synthesized by an ion-exchange reaction. CaPP exhibits a crystalline phase at a low polymerization degree and transitions to an amorphous phase as the polymerization degree increases. Notably, the addition of Ca2+ enhances the wettability of polyP, and CaPP promotes hemostasis, with varying degrees of effectiveness related to chain length. CaPP-50 exhibits the most promising hemostatic performance, with the lowest blood clotting index (BCI, 12.1 ± 0.7%) and the shortest clotting time (302.0 ± 10.5 s). By combining Ca2+ with polyP of medium-chain length, CaPP-50 demonstrates an enhanced ability to accelerate the adhesion and activation of blood cells, initiate the intrinsic coagulation cascade, and form a stable blood clot, outperforming both CaPP-20 and CaPP-1500. The hemostatic efficacy of CaPP-50 is further validated using rat liver bleeding and femoral artery puncture models. CaPP-50 is proven to possess hemostatic properties comparable to those of commercial calcium-based zeolite hemostatic powder and superior to kaolin. In addition, CaPP-50 exhibits excellent biocompatibility and long-term storage stability. These results suggest that CaPP-50 has significant clinical and commercial potential as an active inorganic hemostatic agent for rapid control of bleeding.

Protonated-chitosan sponge with procoagulation activity for hemostasis in coagulopathy.

Hemostatic materials are essential for managing acute bleeding in medical settings. Chitosan (CS) shows promise in hemostasis but its underlying mechanism remains incompletely understood. We unexpectedly discovered that certain protonated-chitosan (PCS) rapidly assembled plasma proteins to form protein membrane (PM) upon contact with platelet-poor plasma (PPP). We hypothesized that the novel observation was intricately related to the procoagulant effect of chitosan. Herein, the study aimed to elucidate the conditions necessary and mechanism for PM formation, identify the proteins within the PM and PCS's procoagulant action at the molecule levels. We confirmed that the amount of -NH3 + groups (>4.9 mmol/g) on PCS molecules played a crucial role in promoting coagulation. The -NH3 + group interacted with blood's multiple active components to exert hemostatic effects: assembling plasma proteins including coagulation factors such as FII, FV, FX, activating blood cells and promoting the secretion of coagulation-related substances (FV, ADP, etc) by platelets. Notably, the hemostatic mechanism can be extended to protonated-chitosan derivatives like quaternized, alkylated, and catechol-chitosan. In the blood clotting index (BCI) experiment, compared to other groups, PCS95 achieved the lowest BCI value (∼6 %) within 30 s. Protonated-chitosan exhibited excellent biocompatibility and antibacterial properties, with PCS95 demonstrating inhibition effectiveness of over 95 % against Escherichia coli (E.coil) and Staphylococcus aureus (S. aureus). Moreover, PCS performed enhanced hemostatic effectiveness over chitosan-based commercially agents (Celox™ and ChitoGauze®XR) in diverse bleeding models. In particular, PCS95 reduced bleeding time by 70 % in rabbit models of coagulopathy. Overall, this study investigated the coagulation mechanism of materials at the molecular level, paving the way for innovative approaches in designing new hemostatic materials.

Polarization-Accelerated Seawater Splash Simulation for Rapid Evaluation of Protection Performance of an Epoxy Coating on Carbon Steel.

The application of organic coatings is the most cost-effective and common method for metallic equipment toward corrosion, whose anti-corrosion property needs to be improved and evaluated in a short time. To rapidly and rationally assess the anti-corrosion property of organic coatings in the ocean splash zone, a new accelerated test was proposed. In the study, the corrosion protection property of the coating samples was measured by an improved AC-DC-AC test in a simulated seawater of 3.5 wt.% NaCl solution, a simulated ocean splash zone test and a new accelerated test combining the above two tests. The results showed that the corrosion rate of the coating samples was high in the improved AC-DC-AC test, which lost its anti-corrosion property after 24 cycles equal to 96 h. The main rapid failure reason was that the time of the water and corrosive media arriving at the carbon steel substrate under the alternating cathodic and anodic polarization with symmetrical positive and negative electric charges was shortened. The entire impedance of the coating samples was improved by about 1.6 times more than that in the initial early time in the simulated ocean splash zone test, which was caused by the damage effect from the salt spraying, drying, humidifying, salt immersion, high temperature and UVA irradiation being weaker than the enhancement effect from the post-curing process by the UVA irradiation. In the new accelerated test, the samples lost their corrosion resistance after 12 cycles equal to 288 h with the fastest failure rate. On account of the coupling process of the salt spraying, drying, humidifying, salt immersion, high temperature combined with the cathodic and anodic polarization and the UVA irradiation, the penetration and transmission rate of water and corrosive media in the coating were further accelerated, the corrosion rate on the carbon steel substrate was reinforced even larger and the destruction of the top polymer molecules was more serious. The new accelerated test showed the strongest damage-acceleration effect than that in the other two tests.

Boron Cluster Renders Organic Radicals Water-Stable for Photothermal Anti-Infections.

Water-stable organic radicals are promising photothermal conversion candidates for photothermal therapy (PTT). However, organic radicals are usually unstable in biological environments, which greatly hinders their wide application. Here, we have developed a chaotropic effect-based and photoinduced water-stable supramolecular radical (MB12-2) for efficient antibacterial PTT. The supramolecular radical precursor MB12-1 was constructed by the chaotropic effect between closo-dodecaborate cluster (B12H122-) and N,N'-dimethylated dipyridinium thiazolo [5,4-d] thiazole (MPT2+). Subsequently, with triethanolamine (TEOA) serving as an electron donor, MB12-1 could transform to its radical form MB12-2 through photoinduced electron transfer (PET) under 435-nm laser irradiation. The N2 adsorption-desorption analysis confirmed that MB12-2 was tightly packed through the introduction of B12H122-, which effectively enhanced its stability via a spatial site-blocked effect. Moreover, the half-life of MB12-2 in water was calculated through ultraviolet-visible light (UV-vis) absorption spectra results for periods as long as 20 days. In addition, in the skin infection model, MB12-2, as a wound dressing, showed remarkable photothermal antibacterial activity (>97%) under 660-nm laser irradiation and promoted wound healing. This study presents a simple method for designing long-term water-stable supramolecular radicals, offering a novel avenue for noncontact treatments for bacterial infections.

Evaluation of deep learning-based reconstruction late gadolinium enhancement images for identifying patients with clinically unrecognized myocardial infarction.

BACKGROUND: The presence of infarction in patients with unrecognized myocardial infarction (UMI) is a critical feature in predicting adverse cardiac events. This study aimed to compare the detection rate of UMI using conventional and deep learning reconstruction (DLR)-based late gadolinium enhancement (LGEO and LGEDL, respectively) and evaluate optimal quantification parameters to enhance diagnosis and management of suspected patients with UMI. METHODS: This prospective study included 98 patients (68 men; mean age: 55.8 ± 8.1 years) with suspected UMI treated at our hospital from April 2022 to August 2023. LGEO and LGEDL images were obtained using conventional and commercially available inline DLR algorithms. The myocardial signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and percentage of enhanced area (Parea) employing the signal threshold versus reference mean (STRM) approach, which correlates the signal intensity (SI) within areas of interest with the average SI of normal regions, were analyzed. Analysis was performed using the standard deviation (SD) threshold approach (2SD-5SD) and full width at half maximum (FWHM) method. The diagnostic efficacies based on LGEDL and LGEO images were calculated. RESULTS: The SNRDL and CNRDL were two times better than the SNRO and CNRO, respectively (P < 0.05). Parea-DL was elevated compared to Parea-O using the threshold methods (P < 0.05); however, no intergroup difference was found based on the FWHM method (P > 0.05). The Parea-DL and Parea-O also differed except between the 2SD and 3SD and the 4SD/5SD and FWHM methods (P < 0.05). The receiver operating characteristic curve analysis revealed that each SD method exhibited good diagnostic efficacy for detecting UMI, with the Parea-DL having the best diagnostic efficacy based on the 5SD method (P < 0.05). Overall, the LGEDL images had better image quality. Strong diagnostic efficacy for UMI identification was achieved when the STRM was ≥ 4SD and ≥ 3SD for the LGEDL and LGEO, respectively. CONCLUSIONS: STRM selection for LGEDL magnetic resonance images helps improve clinical decision-making in patients with UMI. This study underscored the importance of STRM selection for analyzing LGEDL images to enhance diagnostic accuracy and clinical decision-making for patients with UMI, further providing better cardiovascular care.

Hsa_circ_0004872 mitigates proliferation, metastasis and immune escape of meningioma cells by suppressing PD-L1.

Meningioma is a prevalent intracranial malignancy known for its aggressive growth. Circular RNAs (circRNAs) play a crucial role in the development of various cancers. However, their involvement in meningioma remains understudied. This study aimed to investigate the function and underlying mechanism of hsa_circ_0004872 in meningioma. The molecular expression of hsa_circ_0004872, PD-L1 and EIF4A3 was identified by RT-qPCR and/or western blot assays. Cell viability, migration, and invasion were assessed through CCK-8 and Transwell assays, respectively. Cytotoxicity was determined using an LDH assay, and cell apoptosis was monitored by flow cytometry. The RNA and protein interactions were assessed through RNA-protein immunoprecipitation (RIP) and RNA pull down analyses. Our findings revealed that hsa_circ_0004872 expression was significantly downregulated in both meningioma tissue samples and cells. Overexpression of hsa_circ_0004872 inhibited the proliferation, metastasis, and immune escape of meningioma cells, as well as enhanced the cytotoxicity of CD8+ T cells by suppressing PD-L1. Furthermore, hsa_circ_0004872 directly interacted with EIF4A3, leading to the degradation of PD-L1 mRNA. Finally, inhibiting EIF4A3 improved the proliferation, metastasis, and immune escape of meningioma cells, as well as the cytotoxicity of CD8+ T cells. Our study demonstrated that hsa_circ_0004872 mitigated the proliferation, metastasis,and immune escape of meningioma cells by targeting the EIF4A3/PD-L1 axis. These findings suggested that hsa_circ_0004872 and EIF4A3 might serve as promising biological markers and therapeutic targets for meningioma treatment.

Regulating the bioactivity of non-glycosylated recombinant human bone morphogenetic protein-2 to enhance bone regeneration.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is the predominant growth factor that effectively induces osteogenic differentiation in orthopedic procedures. However, the bioactivity and stability of rhBMP-2 are intrinsically associated with its sequence, structure, and storage conditions. In this study, we successfully determined the amino acid sequence and protein secondary structure model of non-glycosylated rhBMP-2 expressed by an E. coli expression system through X-ray crystal structure analysis. Furthermore, we observed that acidic storage conditions enhanced the proliferative and osteoinductive activity of rhBMP-2. Although the osteogenic activity of non-glycosylated rhBMP-2 is relatively weaker compared to glycosylated rhBMP-2; however, this discrepancy can be mitigated by incorporating exogenous chaperone molecules. Overall, such information is crucial for rationalizing the design of stabilization methods and enhancing the bioactivity of rhBMP-2, which may also be applicable to other growth factors.

Decellularized extracellular matrix enriched with GDNF enhances neurogenesis and remyelination for improved motor recovery after spinal cord injury.

Motor functional improvement represents a paramount treatment objective in the post-spinal cord injury (SCI) recovery process. However, neuronal cell death and axonal degeneration following SCI disrupt neural signaling, impeding the motor functional recovery. In this study, we developed a multifunctional decellularized spinal cord-derived extracellular matrix (dSECM), crosslinked with glial cell-derived neurotrophic factor (GDNF), to promote differentiation of stem cells into neural-like cells and facilitate axonogenesis and remyelination. After decellularization, the immunogenic cellular components were effectively removed in dSECM, while the crucial protein components were retained which supports stem cells proliferation and differentiation. Furthermore, sustained release of GDNF from the dSECM facilitated axonogenesis and remyelination by activating the PI3K/Akt and MEK/Erk pathways. Our findings demonstrate that the dSECM-GDNF platform promotes neurogenesis, axonogenesis, and remyelination to enhance neural signaling, thereby yielding promising therapeutic effects for motor functional improvement after SCI. STATEMENT OF SIGNIFICANCE: The dSECM promotes the proliferation and differentiation of MSCs or NSCs by retaining proteins associated with positive regulation of neurogenesis and neuronal differentiation, while eliminating proteins related to negative regulation of neurogenesis. After crosslinking, GDNF can be gradually released from the platform, thereby promoting neural differentiation, axonogenesis, and remyelination to enhance neural signaling through activation of the PI3K/Akt and MEK/Erk pathways. In vivo experiments demonstrated that dSECM-GDNF/MSC@GelMA hydrogel exhibited the ability to facilitate neuronal regeneration at 4 weeks post-surgery, while promoting axonogenesis and remyelination at 8 weeks post-surgery, ultimately leading to enhanced motor functional recovery. This study elucidates the ability of neural regeneration strategy to promote motor functional recovery and provides a promising approach for designing multifunctional tissue for SCI treatment.

Swift Covalent Gelation Coupled with Robust Wet Adhesive Powder: A Novel Approach for Acute Massive Hemorrhage Control in Dynamic and High-Pressure Wound Environments.

The quest for efficient hemostatic agents in emergency medicine is critical, particularly for managing massive hemorrhages in dynamic and high-pressure wound environments. Traditional self-gelling powders, while beneficial due to their ease of application and rapid action, fall short in such challenging conditions. To bridge this gap, the research introduces a novel self-gelling powder that combines ultrafast covalent gelation and robust wet adhesion, presenting a significant advancement in acute hemorrhage control. This ternary system comprises ε-polylysine (ε-PLL) and 4-arm polyethylene glycol succinyl succinate (4-arm-PEG-NHS) forming the hydrogel framework. Na2HPO4 functions as the "H+ sucker" to expedite the amidation reaction, slashing gelation time to under 10 s, crucial for immediate blood loss restriction. Moreover, PEG chains' hydrophilicity facilitates efficient absorption of interfacial blood, increasing the generated hydrogel's cross-linking density and strengthens its tissue bonding, thereby resulting in excellent mechanical and wet adhesion properties. In vitro experiments reveal the optimized formulation's exceptional tissue compliance, procoagulant activity, biocompatibility and antibacterial efficacy. In porcine models of heart injuries and arterial punctures, it outperforms commercial hemostatic agent Celox, confirming its rapid and effective hemostasis. Conclusively, this study presents a transformative approach to hemostasis, offering a reliable and potent solution for the emergency management of massive hemorrhage.

Sulfated Polysaccharide-Based Nanocarrier Drives Microenvironment-Mediated Cerebral Neurovascular Remodeling for Ischemic Stroke Treatment.

Stroke is a leading cause of global mortality and severe disability. However, current strategies used for treating ischemic stroke lack specific targeting capabilities, exhibit poor immune escape ability, and have limited drug release control. Herein, we developed an ROS-responsive nanocarrier for targeted delivery of the neuroprotective agent rapamycin (RAPA) to mitigate ischemic brain damage. The nanocarrier consisted of a sulfated chitosan (SCS) polymer core modified with a ROS-responsive boronic ester enveloped by a red blood cell membrane shell incorporating a stroke homing peptide. When encountering high levels of intracellular ROS in ischemic brain tissues, the release of SCS combined with RAPA from nanoparticle disintegration facilitates effective microglia polarization and, in turn, maintains blood-brain barrier integrity, reduces cerebral infarction, and promotes cerebral neurovascular remodeling in a mouse stroke model involving transient middle cerebral artery occlusion (tMCAO). This work offers a promising strategy to treat ischemic stroke therapy.

Biomaterial design for regenerating aged bone: materiobiological advances and paradigmatic shifts.

China's aging demographic poses a challenge for treating prevalent bone diseases impacting life quality. As bone regeneration capacity diminishes with age due to cellular dysfunction and inflammation, advanced biomaterials-based approaches offer hope for aged bone regeneration. This review synthesizes materiobiology principles, focusing on biomaterials that target specific biological functions to restore tissue integrity. It covers strategies for stem cell manipulation, regulation of the inflammatory microenvironment, blood vessel regeneration, intervention in bone anabolism and catabolism, and nerve regulation. The review also explores molecular and cellular mechanisms underlying aged bone regeneration and proposes a database-driven design process for future biomaterial development. These insights may also guide therapies for other age-related conditions, contributing to the pursuit of 'healthy aging'.

Biomaterial-assisted therapeutic cell production and modification in vivo.

Hematopoietic stem cell transplantation remains the preferred treatment for a variety of hematopoietic function disorders. To address the issue of limited numbers of hematopoietic stem/progenitor cells (HSPCs), significant progress has been made in the technology for ex vivo expansion of HSPCs. In addition, biomaterial-assisted in vivo production technology for therapeutic cells, including HSPCs, is gradually gaining attention. With the aid of specifically functional biomaterials, researchers can construct bone-like tissues exhibiting typical bone marrow-like structures (termed in vivo osteo-organoids in this article) for the production of therapeutic cells. These in vivo osteo-organoids mimic the native bone marrow niche and provide a microenvironment conducive to the expansion and differentiation of HSPCs. In this perspective article, we systematically summarize the history of in vivo osteo-organoids as a model for studying hematopoiesis and cancer metastasis and propose the challenges faced by the in vivo osteo-organoid production platform for therapeutic cells in terms of clinical translation. Ultimately, we hope to achieve functional customization of in vivo osteo-organoid-derived cells through continuously developed material design methods, so as to meet the treatment needs of different types of diseases and bring hope for life to more people.

[Expert consensus on integrated traditional Chinese and western medicine diagnosis and treatment for osteoporotic fractures].

Osteoporotic fractures represent the most severe complications of osteoporosis,characterized by insidious onset,high mortality and disability rates,and a steadily increasing incidence,imposing a significant socioeconomic burden. Western medicine has advantages in diagnosis and surgical interventions,while traditional Chinese medicine excels in holistic management and the restoration of bodily equilibrium. The integration of both traditional Chinese medicine (TCM) and western medicine emerges as an effective therapeutic strategy for osteoporotic fractures. In order to propagate the concept of integrated diagnosis and treatment,foster the advancement of integrated medical techniques for osteoporotic fractures,and establish standardized and normative protocols for disease prevention,diagnosis,and treatment,a consensus expert group,led by Geriatric Branch of Chinese Geriatrics Society,the Young Osteoporosis Group of Orthopedics Branch of Chinese Medical Association,Osteoporosis Group of Orthopedics Branch of Chinese Physician Association,and Osteoporosis Professional Committee of the Shanghai Society of Integrated Traditional Chinese and Western Medicine,was established. This group engaged in deliberations and formulated the "Expert Consensus on Integrated Traditional Chinese and Western Medicine Diagnosis and Treatment of Osteoporotic Fractures" elucidating the concept of integrated medicine and offering recommendations in the domains of prevention,diagnosis,and treatment,with the aspiration of ameliorating the prognosis of osteoporotic fractures and enhancing the quality of life for these patients.

Comparison evaluation pretreatments on the quality characteristics, oxidative stability, and volatile flavor of walnut oil.

In this study, we applied various thermal pretreatment methods (e.g., hot-air, microwave, and stir-frying) to process walnut kernels, and conducted comparative analysis of the physicochemical properties, nutritional components, in vitro antioxidant activity, and flavor substances of the extracted walnut oil (WO). The results indicated that, thermal pretreatment significantly increased the extraction of total trace nutrients (e.g., total phenols, tocopherols, and phytosterols) in WO. The WO produced using microwave had 2316.71 mg/kg of total trace nutrients, closely followed by the stir-frying method, which yielded an 11.22% increase compared to the untreated method. The WO obtained by the microwave method had a higher Oxidative inductance period (4.05 h) and oil yield (2.48%). After analyzing the flavor in WO, we found that aldehydes accounted for 28.77% of the 73 of volatile compounds and 58.12% of the total flavor compound content in microwave-pretreated WO, these percentages were higher than those recorded by using other methods. Based on the comprehensive score obtained by the PCA, microwave-pretreatment might be a promising strategy to improve the quality of WO based on aromatic characteristics.

In Vivo Osteo-organoid Approach for Harvesting Therapeutic Hematopoietic Stem/Progenitor Cells.

Hematopoietic stem cell transplantation (HSCT) requires a sufficient number of therapeutic hematopoietic stem/progenitor cells (HSPCs). To identify an adequate source of HSPCs, we developed an in vivo osteo-organoid by implanting scaffolds loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2) into an internal muscle pouch near the femur in mice. After 12 weeks of implantation, we retrieved the in vivo osteo-organoids and conducted flow cytometry analysis on HPSCs, revealing a significant presence of HSPC subsets within the in vivo osteo-organoids. We then established a sublethal model of hematopoietic/immune system injury in mice through radiation and performed hematopoietic stem cell transplantation (HSCT) by injecting the extracted osteo-organoid-derived cells into the peripheral blood of radiated mice. The effect of hematopoietic recovery was evaluated through hematological, peripheral blood chimerism, and solid organ chimerism analyses. The results confirmed that in vivo osteo-organoid-derived cells can rapidly and efficiently reconstruct damaged peripheral and solid immune organs in irradiated mice. This approach holds potential as an alternative source of HSPCs for HSCT, offering benefits to a larger number of patients.

The Effect of Process Parameters on the Temperature and Stress Fields in Directed Energy Deposition Inconel 690 Alloy.

Additive manufacturing (AM) technology has the advantages of designability, short process times, high flexibility, etc., making it especially suitable for manufacturing complex high-performance components for high-end industrial systems. However, the intensive temperature gradients caused by the rapid heating and cooling processes of AM can generate high levels of residual stresses, which directly affect the precision and serviceability of the components. Taking Inconel 690 alloy, which is widely used in nuclear power plants, as the research object, a thermo-coupled mechanical model of temperature field and residual stress field of directed energy deposition (DED) of Inconel 690 was established based on ABAQUS 2019 finite element software to study the influence of process parameters on the temperature history and the distribution of residual stresses in the DED process. The experimental results show that the peak temperature of each layer in the fabrication process increases with the increase in laser power and preheating temperature, and decreases with the increase in scanning speed and interlayer dwell time. Substrate preheating only has a large effect on the peak temperature of the first four layers. Residual stresses are mainly concentrated in the upper and middle parts, the bottom of the substrate, and the sides combined with the substrate, and the residual stresses increase with the increasing laser power and decrease with the increasing interlayer dwell time. Decreasing laser power, longer dwell time, higher preheating temperature, and appropriate scanning speed are beneficial for the reduction in residual stresses in Inconel 690 components. This research has important significance for the process design and residual stress modulation in the additive manufacturing of Inconel 690 alloy.