Rab27a-mediated extracellular vesicle secretion contributes to osteogenesis in periodontal ligament-bone niche communication

In situ architecture of the intercellular organelle reservoir between epididymal epithelial cells by volume electron microscopy

Mammalian epididymal epithelial cells are crucial for sperm maturation. Historically, vacuole-like ultrastructures in epididymal epithelial cells were observed via transmission electron microscopy but were undefined. Here, we utilize volume electron microscopy (vEM) to generate 3D reconstructions of epididymal epithelial cells and identify these vacuoles as intercellular organelle reservoirs (IORs) in the lateral intercellular space (LIS), which contains protein aggregates, autophagosomes, lysosome-related organelles and mitochondrial residues. Immunolabelling of organelle markers such as P62, LC3, LAMP1 and TOMM20 confirm these findings. The IOR size or number varies across four epididymal regions and decreases with age. Rab27a mutant mice exhibit reduced IORs in the caput epididymis and a subfertility phenotype, suggesting the involvement of Rab27a in the formation of IORs. Furthermore, we observe the presence of IORs between intestinal epithelial cells besides epididymis. Amino acid transporters at IOR edges suggest dynamic protein recycling. Our findings reveal that the IOR is an important structure critical for organelle turnover and recycling outside epithelial cells with limited self-degradation capabilities.

Mesenchymal stem cell-derived extracellular vesicles in periodontal bone repair

Periodontitis is a chronic inflammatory disease that destroys tooth-supporting structures and poses significant public health challenges due to its high prevalence and links to systemic health conditions. Traditional treatments are effective in reducing the inflammatory response and improving the clinical symptoms of periodontitis. However, these methods are challenging to achieve an ideal treatment effect in alveolar bone repair. Mesenchymal stem cells (MSCs) represent a potential alternative for the treatment of periodontal bone defects due to their self-renewal and differentiation capabilities. Recent research indicates that MSCs exert their effects primarily through paracrine mechanisms. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) serve as pivotal mediators in intercellular communication, transferring microRNAs (miRNAs), messenger RNAs (mRNAs), proteins, and cytokines to recipient cells, thereby emulating the therapeutic effects of MSCs. In periodontitis, MSC-EVs play a pivotal role in immunomodulation and bone remodeling, thereby facilitating periodontal bone repair. As a cell-free therapy, MSC-EVs demonstrate considerable clinical potential due to their specialized membrane structure, minimal immunogenicity, low toxicity, high biocompatibility, and nanoscale size. This review indicates that MSC-EVs represent a promising approach for periodontitis treatment, with the potential to overcome the limitations of traditional therapies and offer a more effective solution for bone repair in periodontal disease. In this review, we introduce MSC-EVs, emphasizing their mechanisms and clinical applications in periodontal bone repair. It synthesizes recent advances, existing challenges, and future prospects to present up-to-date information and novel techniques for periodontal regeneration and to guide the improvement of MSC-EV therapy in clinical practice.

Odontogenesis-Empowered Extracellular Vesicles Safeguard Donor-Recipient Stem Cell Interplay to Support Tooth Regeneration

Harnessing the developmental events of mesenchymal condensation to direct postnatal dental stem cell aggregation represents a cutting-edge and promising approach to tooth regeneration. Tooth avulsion is among the most prevalent and serious dental injuries, and odontogenic aggregates assembled by stem cells from human exfoliated deciduous teeth (SHED) have proven effective in revitalizing avulsed teeth after replantation in the clinical trial. However, whether and how SHED aggregates (SA) communicate with recipient components and promote synergistic tissue regeneration to support replanted teeth remains elusive. Here, it is shown that SA-mediated avulsed tooth regeneration involves periodontal restoration and recovery of recipient Gli1+ stem cells, which are mobilized and necessarily contribute to the reestablishment of the tooth-periodontal ligament-bone interface. Mechanistically, the release of extracellular vesicles (EVs) is revealed indispensable for the implanted SA to mobilize recipient Gli1+ cells and regenerate avulsed teeth. Furthermore, SHED aggregates-released EVs (SA-EVs) are featured with odontogenic properties linked to tissue regeneration, which enhance migration, proliferation, and differentiation of Gli1+ cells. Importantly, local application of SA-EVs per se empowers recipient Gli1+ cells and safeguards regeneration of avulsed teeth. Collectively, the findings establish a paradigm in which odontogenesis-featured EVs govern donor-recipient stem cell interplay to achieve tooth regeneration, inspiring cell-free translational regenerative strategies.

Jaw osteoporosis: Challenges to oral health and emerging perspectives of treatment

Osteoporosis is a prevalent bone metabolic disease that poses a significant challenge to global human health. Jaw osteoporosis, characterized by microstructural damage of the jaw resulting from various factors, is one of the common manifestations of this condition. Recent studies have demonstrated that jaw osteoporosis has multifaceted effects on oral health and can negatively impact conditions such as periodontitis, oral implantation, orthodontic treatment, and wound healing. However, there are still some limitations in the conventional treatment of osteoporosis. For instance, while bisphosphonates can enhance bone quality, they may also lead to osteonecrosis of the jaw, which poses a potential safety hazard in oral diagnosis and treatment. In recent years, considerable attention has been focused on improving the pathological condition of jaw osteoporosis. Treatment strategies such as gut microbial regulation, extracellular vesicles, molecular targeted therapy, herbal medicine, mechanical stimulation are expected to enhance efficacy and minimize adverse reactions. Therefore, understanding these effects and exploring novel treatments for jaw osteoporosis may provide new insights for oral health maintenance and disease treatment. This article reviews the impact of jaw osteoporosis on oral health and describes the limitations associated with current methods. It also discusses emerging perspectives on treatment, offering a comprehensive overview of the challenges and future directions in managing jaw osteoporosis.

Extracellular vesicles miR-31-5p promotes pancreatic cancer chemoresistance via regulating LATS2-Hippo pathway and promoting SPARC secretion from pancreatic stellate cells

Pancreatic cancer remains one of the most lethal malignant diseases. Gemcitabine-based chemotherapy is still one of the first-line systemic treatments, but chemoresistance occurs in the majority of patients. Recently, accumulated evidence has demonstrated the role of the tumour microenvironment in promoting chemoresistance. In the tumour microenvironment, pancreatic stellate cells (PSCs) are among the main cellular components, and extracellular vesicles (EVs) are common mediators of cell‒cell communication. In this study, we showed that SP1-transcribed miR-31-5p not only targeted LATS2 in pancreatic cancer cells but also regulated the Hippo pathway in PSCs through EV transfer. Consequently, PSCs synthesized and secreted protein acidic and rich in cysteins (SPARC), which was preferentially expressed in stromal cells, stimulating Extracellular Signal regulated kinase (ERK) signalling in pancreatic cancer cells. Therefore, pancreatic cancer cell survival and chemoresistance were improved due to both the intrinsic Hippo pathway regulated by miR-31-5p and external SPARC-induced ERK signalling. In mouse models, miR-31-5p overexpression in pancreatic cancer cells promoted the chemoresistance of coinjected xenografts. In a tissue microarray, pancreatic cancer patients with higher miR-31-5p expression had shorter overall survival. Therefore, miR-31-5p regulates the Hippo pathway in multiple cell types within the tumour microenvironment via EVs, ultimately contributing to the chemoresistance of pancreatic cancer cells.

circ_0029463 promotes osteoclast differentiation by mediating miR-134-5p/Rab27a axis

OBJECTIVE

Osteoporosis is the imbalance in bone homeostasis between osteoblasts and osteoclasts. In this study, we investigated the effects of the circ_0029463/miR-134-5p/Rab27a axis on RANKL-induced osteoclast differentiation.

METHODS

RT-qPCR and western blotting were used to detect the expression of circ_0029463, miR-134-5p, and Rab27a in tissues from patients with osteoporosis and in RANKL-induced osteoclasts. Osteoclast differentiation was verified by TRAP staining. Osteoclast biomarkers, including NFATc1, TRAP, and CTSK, were measured. The target and regulatory relationships between circ_0029463, miR-134-5p, and the Rab27a axis were verified using RIP, dual-luciferase reporter gene, and RNA pull-down assays.

RESULTS

Elevated expression of circ_0029463 and Rab27a and decreased miR-134-5p expression were observed in the tissues of patients with osteoporosis, and a similar expression pattern was observed in RANKL-induced osteoclasts. Suppression of circ_0029463 expression or miR-134-5p overexpression curbed RANKL-induced osteoclast differentiation, whereas such an effect was abolished by Rab27 overexpression. circ_0029463 sponges miR-134-5p to induce Rab27a expression.

CONCLUSION

circ_0029463 sponges miR-134-5p to abolish its suppressive effect of miR-134-5p on Rab27a expression, thereby promoting osteoclast differentiation.

Improving physio-mechanical and biological properties of 3D-printed PLA scaffolds via in-situ argon cold plasma treatment

As a bone tissue engineering material, polylactic acid (PLA) has received significant attention and interest due to its ease of processing and biocompatibility. However, its insufficient mechanical properties and poor wettability are two major drawbacks that limit its extensive use. For this purpose, the present study uses in-situ cold argon plasma treatment coupled with a fused deposition modeling printer to enhance the physio-mechanical and biological behavior of 3D-printed PLA scaffolds. Following plasma treatment, field emission scanning electron microscopy images indicated that the surface of the modified scaffold became rough, and the interlayer bonding was enhanced. This resulted in an improvement in the tensile properties of samples printed in the X, Y, and Z directions, with the enhancement being more significant in the Z direction. Additionally, the root mean square value of PLA scaffolds increased (up to 70-fold) after plasma treatment. X-ray photoelectron spectroscopy analysis demonstrated that the plasma technique increased the intensity of oxygen-containing bonds, thereby reducing the water contact angle from 92.5° to 42.1°. The in-vitro degradation study also demonstrated that argon plasma treatment resulted in a 77% increase in PLA scaffold degradation rate. Furthermore, the modified scaffold improved the viability, attachment, and proliferation of human adipose-derived stem cells. These findings suggest that in-situ argon plasma treatment may be a facile and effective method for improving the properties of 3D-printed parts for bone tissue engineering and other applications.