Bone marrow mesenchymal stromal cell-derived exosomes (BMSC-Exos) can recruit stem cells for bone repair, with neovessels serving as the main migratory channel for stem cells to the injury site. However, existing exosome (Exo) delivery strategies cannot reach the angiogenesis phase following bone injury. To that end, an enzyme-sensitive Exo delivery material that responds to neovessel formation during the angiogenesis phase was designed in the present study to achieve spatiotemporally controlled Exo release. Herein, matrix metalloproteinase-1 (MMP1) was found to be highly expressed in neovascularized bone; as a result, we proposed an injectable MMP1-sensitive hydrogel microspheres (KGE) made using a microfluidic chip prepared by mixing self-assembling peptide (KLDL-MMP1), GelMA, and BMSC-Exos. The results revealed that KGE microspheres had a uniform diameter of 50-70 µm, ideal for minimally invasive injection and could release exosomes in response to MMP1 expression. In vitro experiments demonstrated that KGE had less cytotoxicity and could promote the migration and osteodifferentiation of BMSCs. Furthermore, in vivo experiments confirmed that KGE could promote bone repair during angiogenesis by recruiting CD90⁺ stem cells via neovessels. Collectively, our results suggest that injectable enzyme-responsive KGE microspheres could be a promising Exo-secreting material for accelerating neovascularized bone healing. STATEMENT OF SIGNIFICANCE: Exosomes can spread through blood vessels and activate stem cells to participate in bone repair, but under normal circumstances, exosomes lacking sustained-release delivery materials cannot be maintained until the angiogenesis phase. In this study, we found that MMP1 was highly expressed in neovascularized bone, then we proposed an MMP1-sensitive injectable microsphere that carries exosomes and responds temporally and spatially to neovascularization, which maximizes the ability of exosomes to recruit stem cells. Different from previous strategies that focus on promoting angiogenesis to accelerate bone healing, this is a brand new delivery strategy that is stimuli-responsive to neovessel formation. In addition, the preparation of self-assembled peptide microspheres by a microfluidic chip is also proposed for the first time.

Background: Surgical sutures for sealing gastric perforations (GP) are associated with severe inflammation and postoperative adhesions. Hydrogel bioadhesives offer a potential alternative for sutureless repair of GP; however, their application in minimally invasive surgery is limited due to their prefabricated patch-form, lacking in situ gelation capability. In this study, we emphasized an all-in-one minimally invasive strategy for sutureless repair of acute GP.

The slow proliferation rate and poor osteodifferentiation ability of inflammatory periodontal membrane stem cells extracted from periodontitis tissues (i-PDLSCs) account for poor efficiency in treating inflammatory bone loss. Exosomes reportedly have inducible and relatively stable components, allowing them to promote inflammatory bone repair, but obtaining i-PDLSCs exosomes with the ability to promote osteodifferentiation is challenging. In the present study, i-PDLSCs were extracted from periodontal membrane tissues of patients with severe periodontitis, and in vitro induction with gallic acid (GA) significantly promoted the proliferative activity of i-PDLSCs at a concentration of 10 mM, with TC₀ of 11.057 mM and TC₅₀ of 67.56 mM for i-PDLSCs. After mRNA sequencing, we found that GA could alleviate oxidative stress in i-PDLSCs and increase its mitochondrial membrane potential and glucose aerobic metabolism level, thus promoting the osteodifferentiation of i-PDLSCs. After exosomes of i-PDLSCs after GA induction (i-EXO-GA) were isolated by differential centrifugation, we found that 200 ug/mL of i-EXO-GA could remarkably promote the osteodifferentiation of i-PDLSCs. Overall, our results suggest that GA induction can enhance the proliferation and osteodifferentiation in primary cultures of i-PDLSCs in vitro, mediated by alleviating oxidative stress and glycometabolism levels in cells, which further influences the osteodifferentiation-promoting ability of i-EXO-GA. Overall, we provide a viable cell and exosome induction culture method for treating inflammatory alveolar defects associated with periodontitis.

Infrapatellar fat pad mesenchymal stem cells (IPFP-MSCs) extracellular vesicles (EVs) are found to be capable of accelerating Osteoarthritis (OA) progression. However, which pathways and which pathogenic EVs subgroups are involved are not defined. In our study we found that there were a higher percentage of TOMM20⁺ EV's within the total synovial fluid EV's from OA patients than from trauma patients as well as increased mtDNA content. This implicates the mitochondria derived EV sub-group - mitochondria derived vesicles (MDVs) as a potential driver in OA. We found with the single-cell data that MDVs may be secreted from IPFP-MSCs with VPS35. Furthermore, these cells were harvested from the body of the OA patient. IPFP-MSC derived MDVs can deliver exogenous mtDNA to chondrocytes by fusing directly, thus inhibiting chondrocyte matrix synthesis, inducing mitochondrial dysfunction, and activating pro-inflammatory signaling cascades in chondrocytes. Protein microarrays showed that MDVs delivered exogenous mtDNA to chondrocytes, which then activated the cGAS-STING pathway and downstream inflammatory mediators (TBK1, NF-κB, TNF-α). Intra-articular MDV injection worsened cartilage degradation and synovitis in OA rats but STING inhibition alleviated them. This study showed that IPFP-MSC-derived MDVs are essential for OA pathogenesis via mtDNA transfer and cGAS-STING pathway activation. These results show how the mitochondria and immune system talk to each other in the joints causing pain and destroying the cartilage, MDVs are new things that can tell us if someone has this disease and help doctors fix it. Pharmacological blockade of the cGAS-STING axis has shown therapeutic potential, providing a dual approach to mitigate mitochondrial stress and innate immune hyperactivation in OA.

Non-essential proteins for viral replication affect host cell metabolism, while the function of the UL43 protein of herpes simplex virus 1 (HSV-1) is not clear. Herein, we performed a comprehensive microarray analysis of HUVEC cells infected with HSV-1 and its UL43-deficient mutant and found significant variation in genes associated with cellular energy metabolic pathways. The localization of UL43 protein in host cells and how it affects cellular energy metabolism pathways were further investigated. Internalization analysis showed that the UL43 protein could be endocytosis-mediated by YPLF motif (aa144–147) and localized to mitochondria. At the same time, more ATP was produced by coupling with mitochondrial small G protein ARF-like 2 (ARL2) GTPase, which triggered the phosphorylation of ANT1 (SLC25A4) to affect the opening degree of mitochondrial permeability transition pore (mPTP), and significantly promoted the aerobic oxidation and oxidative phosphorylation of glucose. Our study shows that UL43 mediates the improvement of host cell metabolism after HSV-1 infection. Additionally, UL43 protein could be a valuable ATP-stimulating factor for mammalian cells.

Accelerated population aging and rising incidence of bone defects have intensified the need for advanced bone regeneration strategies. While tissue-engineered scaffolds fabricated via 3D printing offer promising alternatives to conventional grafts, most techniques fail to replicate the multi-scale fibrous architecture of native bone extracellular matrix, limiting their biofunctionality. To address this, we developed a hybrid manufacturing strategy integrating low-temperature thermally induced phase separation with extrusion-based 3D printing of polylactic acid (PLA) scaffolds. By optimizing solvent ratios (THF: DMF = 3:1) and freezing temperatures (−196 °C–4 °C), we produced scaffolds with tunable micro-nano fibrous surfaces and macroporous structures. Key findings revealed that scaffolds processed at −196 °C (PLA-196) exhibited the highest porosity (pore size: 6.01 ± 2.06 μm), superior hydrophilicity, and enhanced compressive modulus. These scaffolds significantly promoted BMSC adhesion, proliferation, and osteogenic differentiation via activation of Macf1-mediated pro-osteogenic signaling pathways, leading to elevated expression of Runx2, Ocn, and Col-I. In vivo, PLA-196 scaffolds accelerated cranial defect healing, achieving 62 % bone volume fraction and robust vascularization within 8 weeks. This study demonstrates a scalable, biocompatible platform for fabricating hierarchically structured bone scaffolds that bridge the gap between structural complexity and biological efficacy, offering significant potential for clinical translation in regenerative medicine.