Search

Bone injuries and diseases are associated with profound changes in the biophysical properties of living bone tissues, particularly their electrical and mechanical properties. The biophysical properties of healthy bone are attributed to the complex network of interactions between its various cell types (i.e., osteocytes, osteoclast, immune cells and vascular endothelial cells) with the surrounding extracellular matrix (ECM) against the backdrop of a myriad of biomechanical and bioelectrical stimuli arising from daily physical activities. Understanding the pathophysiological changes in bone biophysical properties is critical to developing new therapeutic strategies and novel scaffold biomaterials for orthopedic surgery and tissue engineering, as well as provides a basis for the application of various biophysical stimuli as therapeutic agents to restore the physiological microenvironment of injured/diseased bone tissue, to facilitate its repair and regeneration. These include mechanical, electrical, magnetic, thermal and ultrasound stimuli, which will be critically examined in this review. A significant advantage of utilizing such biophysical stimuli to facilitate bone healing is that these may be applied non-invasively with minimal damage to surrounding tissues, unlike conventional orthopedic surgical procedures. Furthermore, the effects of such biophysical stimuli can be localized specifically at the bone defect site, unlike drugs or growth factors that tend to diffuse away after delivery, which may result in detrimental side effects at ectopic sites.

Biophysical cues play a crucial role in T cell biology, yet their implications in adoptive T cell therapy (ACT) remain largely unknown. Here, we investigate the effect of electrical stimuli on CD8+ T cells using a charged substrate composed of electroactive nanocomposites with tunable surface charge intensities. Electrical stimuli enhance the persistence and tumor-suppressive efficacy of transferred T cells, with effects dependent on substrate charge. Single-cell RNA-sequencing analysis unveils a decrease in virtual memory T (Tvm) cells and an increase in proliferative potential T (Tpp) cells, which exhibit superior antitumor activity and metabolic adaptations relative to those treated with uncharged substrate. ATAC-seq profiling demonstrates heightened accessibility at upstream binding sites for EGR1, a transcription factor critical for Tpp cell differentiation. Mechanistically, the charged substrate disrupts ionic TCR-lipid interactions, amplifies TCR signaling, and activates EGR1, thereby impeding Tvm polarization during ex vivo culture. Our findings thus highlight the importance of extracellular electrical stimuli in shaping T cell fate, offering potential for optimizing ACT for therapeutic applications. Biophysical cues play a crucial role in T cell biology, yet their implications in adoptive T cell therapy remain elusive. Here the authors use a charged substrate to enhance T cell proliferation and anti-tumor function for adoptive transfer therapy, with the mechanism of amplifying TCR signaling, activating EGR1 signaling and impeding virtual memory T polarization. [ABSTRACT FROM AUTHOR]

The remarkable evolution of teeth morphological complexity represents a giant leap for vertebrate. Despite its importance in life history, the understanding of spatiotemporal organization of teeth remains rudimentary. Herein, a high‐resolution genome‐wide molecular patterning of lineage allocation and cellular organization in tooth morphogenesis is described, constructed by integrating spatial transcriptome and single‐cell RNA sequencing. Twelve spatial compartments and seventeen heterogeneous cell clusters linked to tooth morphogenic milestones are identified. Eighty‐eight percent of total lineage species has already appeared in the initial tooth bud rather than the generally considered sequential emergence. A previously unrecognized sprouting‐like patterning mode of the dental papilla is discovered, that the inner compartment can break through the outer shell compartment to build up the final papilla cusp. Meanwhile, the continuum differentiation hierarchies of enamel knots in time and space are revealed. Furthermore, the regulatory network directing tooth morphogenesis is established, whereby a series of mechanotransduction signals are spatiotemporally involved beyond the well‐established classical odontogenesis signals. Finally, genes underlying tooth dysplasia are successfully tracked to highly specific time points and cell types. The results raise the idea that tooth morphogenesis is orchestrated by mechanical niches combined with biochemical signaling. [ABSTRACT FROM AUTHOR]

Here we designed enantiomeric lipid‐mimetic glutamic acid derivatives (L/D‐UG) and investigated their self‐assembled chiral nanostructures' interaction with the protein adsorption as well as the osteogenesis. It was found that L or D‐UG molecules can self‐assemble into vesicle bilayers and two‐dimensional (2D) nanocrystals via a kinetic and thermodynamic control, respectively. These chiral vesicles and 2D crystals showed differentiated adsorption of proteins, determined by their curvature and chirality. Specifically, fibronectin constituted by L‐amino acids adsorbed preferentially on L‐UG 2D crystal in a semi‐random pattern and L‐2D nanocrystal show as the most effective structures to promote bone regeneration. The controlled vesicle and 2D crystal assemblies with different chirality and curvature helps to clarify their determine roles in protein adsorption and osteogenesis. [ABSTRACT FROM AUTHOR]

Titanosilicate with H2O2 stands out as a highly consequential oxidized catalytic system, prized for its user‐friendly operation, mild conditions, and eco‐friendly attributes. However, a synthesis strategy for large surface area titanosilicalites approaching the theoretical lowest Si/Ti ratio without extra‐framework Ti species remains an ongoing challenge. In this study, we successfully synthesized single‐crystalline Ti‐rich nanosized aggregated TS‐1 by shielding effect with a Si/Ti polymer. This polymer demonstrated effectiveness in restraining TiO2 species by regulating the proximity of Si/Ti species in Ti‐Diol‐Si polymers. The polymer not only facilitated the synthesis of single‐crystalline Ti‐rich TS‐1 but also exploited the chain length of PEG, functioning as a shielding cage by hydrogen bonds, to synthesize nanosized aggregated TS‐1 (TS‐1‐PEG400). This TS‐1‐PEG400 exhibited superior conversion (~60%), selectivity (~90%), and stability in 1‐hexene epoxidation. This study not only establishes a synthesis pathway for Ti‐rich TS‐1 but also holds the potential to enhance related industrial oxidation reactions involving titanosilicates and H2O2. [ABSTRACT FROM AUTHOR]

Angiogenesis is crucial for successful bone defect repair. Co‐transplanting Bone Marrow Stromal Cells (BMSCs) and Endothelial Cells (ECs) has shown promise for vascular augmentation, but it face challenges in hostile tissue microenvironments, including poor cell survival and limited efficacy. In this study, the mitochondria of human BMSCs are isolated and transplanted to BMSCs from the same batch and passage number (BMSCsmito). The transplanted mitochondria significantly boosted the ability of BMSCsmito‐ECs to promote angiogenesis, as assessed by in vitro tube formation and spheroid sprouting assays, as well as in vivo transplantation experiments in balb/c mouse and SD rat models. The Dll4‐Notch1 signaling pathway is found to play a key role in BMSCsmito‐induced endothelial tube formation. Co‐transplanting BMSCsmito with ECs in a rat cranial bone defect significantly improves functional vascular network formation, and improve bone repair outcomes. These findings thus highlight that mitochondrial transplantation, by acting through the DLL4‐Notch1 signaling pathway, represents a promising therapeutic strategy for enhancing angiogenesis and improving bone repair. Hence, mitochondrial transplantation to BMSCS as a therapeutic approach for promoting angiogenesis offers valuable insights and holds much promise for innovative regenerative medicine therapies. [ABSTRACT FROM AUTHOR]

Cluster aggregation states are thermodynamically favored at the subnanoscale, for which an inverse growth from nanoparticles to clusters may be realized on subnanometer supports. Herein, we develop Au‐polyoxometalate‐layered double hydroxide (Au‐POM‐LDH) sub‐1 nm nanosheets (Sub‐APL) based on the above strategy, where sub‐1 nm Au clusters with negative valence are generated by the in situ disintegration of Au nanoparticles on POM‐LDH supports. Sub‐1 nm Au clusters with ultrahigh surface atom ratios exhibit remarkable efficiency for glutathione (GSH) depletion. The closely connected sub‐1 nm Au with negative valence and POM hetero‐units can promote the separation of hole‐electrons, resulting in the enhanced reactive oxygen species (ROS) generation under ultrasound (US). Besides, the reversible redox of Mo in POM is able to deplete GSH and trigger chemodynamic therapy (CDT) simultaneously, further enhancing the oxidative stress. Consequently, the Sub‐APL present 2‐fold ROS generation under US and 7‐fold GSH depletion compared to the discrete Au and POM‐LDH mixture. Therefore, the serious imbalance of redox in the TME caused by the sharp increase of ROS and rapid decrease of GSH leads to death of tumor ultimately. [ABSTRACT FROM AUTHOR]

Radiotherapy plays a vital role in cancer therapy. However, the hypoxic microenvironment of tumors greatly limits the effectiveness, thus it is crucial to develop a simple, efficient, and safe radiosensitizer to reverse hypoxia and ameliorate the efficacy of radiotherapy. Inspired by the structure of canonical nanodrug Abraxane, herein, a native HSA‐modified CaO2 nanoparticle system (CaO2‐HSA) prepared by biomineralization‐induced self‐assembly is developed. CaO2‐HSA will accumulate in tumor tissue and decompose to produce oxygen, altering the hypoxic condition inside the tumor. Simultaneously, ROS and calcium ions will lead to calcium overload and further trigger immunogenic cell death. Notably, its sensitizing enhancement ratio (SER = 3.47) is much higher than that of sodium glycididazole used in the clinic. Furthermore, in animal models of in situ oral cancer, CaO2‐HSA can effectively inhibit tumor growth. With its high efficacy, facile preparation, and heavy‐metal free biosafety, the CaO2‐HSA‐based radiosensitizer holds enormous potential for oral cancer therapy. [ABSTRACT FROM AUTHOR]

Background/Objectives: Glass, bone, and dentin are commonly applied substrates for osteoclast cultures; however, the impact of these substrates on osteoclastogenesis remains underexplored. This study aimed to address a significant gap in understanding how different substrates influence the process of osteoclastogenesis. Methods: RAW 264.7 cells were cultured and induced with RANKL on glass, bone, and dentin slides. Histological and molecular techniques were used to identify patterns and differences in osteoclast behavior on each substrate. Results: Osteoclasts cultured on glass slides possessed the greatest number of nuclei and the highest expression levels of ACP5 (TRAP) and CTSK, with osteoclasts on bone and dentin slides displaying progressively lower levels. Src expression was also most pronounced in osteoclasts on glass slides, with decreased levels observed on bone and dentin. This variation in Src expression likely contributed to differences in cytoskeletal remodeling and oxidative phosphorylation (OXPHOS), resulting in substrate-dependent divergences in osteoclastogenesis. Conclusions: Glass slides were the most favorable substrate for inducing osteoclastogenesis, while bone and dentin slides were less effective. The substrate-induced expression of Src played a fundamental role in shaping the phenotypic divergence of osteoclasts. These insights fill important knowledge gaps and have significant implications for the development and selection of in vitro models for bone-related diseases and drug screening platforms. [ABSTRACT FROM AUTHOR]

Due to the difficulty of forming a low Schottky barrier at the interface of a metal/SiC contact, preparing Ohmic contacts is still a key technical problem in developing SiC devices. In this paper, the effects of MoS2 intercalation on the interface properties of metal/SiC (Al, Ag, Ti, Au, and Mg) systems were investigated by first-principles calculation. The calculations show that all the metal/SiC contacts exhibit p-type Schottky contacts with strong Fermi level pinning (FLP) at the interfaces. After inserting a layer of MoS2, the Schottky barrier heights are significantly reduced. All the metal/MoS2/SiC systems are tuned to be n-type Ohmic contacts. By calculating and analyzing electron localization functions, projected band structure, partial density of states, and planar-averaged charge density difference, the Ohmic contact formation mechanism may be due to the saturation of dangling bonds of the SiC surface, the reduction in metal-induced gap states, the formation of interface dipole layer, and the shift of FLP position to the interface of metal/MoS2. [ABSTRACT FROM AUTHOR]

Macrophages play a pivotal role in the immunological cascade activated in response to biomedical implants, which predetermine acceptance or rejection of implants by the host via pro‐ and anti‐inflammatory polarisation states. The role of chemical signals in macrophage polarisation is well‐established, but how physical cues regulate macrophage function that may play a fundamental role in implant‐bone interface, remains poorly understood. Here we find that bone marrow‐derived macrophages (BMDM) cultured on polyacrylamide gels of varying stiffness exhibit different polarisation states. BMDM are 'primed' to a pro‐inflammatory M1 phenotype on stiff substrates, while to an anti‐inflammatory M2 phenotype on soft and medium stiffness substrates. It is further observed that matrix stiffening increases Piezo1 expression, as well as leads to subsequent activation of the mechanotransduction signalling effector YAP, thus favouring M1 polarisation whilst suppressing M2 polarisation. Moreover, upon treatment with YAP inhibitor, we successfully induce macrophage re‐polarisation to the M2 state within the implant site microenvironment, which in turn promotes implant osseointegration. Collectively, our present study thus characterises the critical role of the Piezo1‐YAP signalling axis in macrophage mechanosensing and stiffness‐mediated macrophage polarisation and provides cues for the design of immuno‐modulatory biomaterials that can regulate the macrophage phenotype. [ABSTRACT FROM AUTHOR]