Delivery of miR-15b-5p via magnetic nanoparticle-enhanced bone marrow mesenchymal stem cell-derived extracellular vesicles mitigates diabetic osteoporosis by targeting GFAP.

Diabetic osteoporosis (DO) presents significant clinical challenges. This study aimed to investigate the potential of magnetic nanoparticle-enhanced extracellular vesicles (GMNPE-EVs) derived from bone marrow mesenchymal stem cells (BMSCs) to deliver miR-15b-5p, thereby targeting and downregulating glial fibrillary acidic protein (GFAP) expression in rat DO models. Data was sourced from DO-related RNA-seq datasets combined with GEO and GeneCards databases. Rat primary BMSCs, bone marrow-derived macrophages (BMMs), and osteoclasts were isolated and cultured. EVs were separated, and GMNPE targeting EVs were synthesized. Bioinformatic analysis revealed a high GFAP expression in DO-related RNA-seq and GSE26168 datasets for disease models. Experimental results confirmed elevated GFAP in rat DO bone tissues, promoting osteoclast differentiation. miR-15b-5p was identified as a GFAP inhibitor, but was significantly downregulated in DO and enriched in BMSC-derived EVs. In vitro experiments showed that GMNPE-EVs could transfer miR-15b-5p to osteoclasts, downregulating GFAP and inhibiting osteoclast differentiation. In vivo tests confirmed the therapeutic potential of this approach in alleviating rat DO. Collectively, GMNPE-EVs can effectively deliver miR-15b-5p to osteoclasts, downregulating GFAP expression, and hence, offering a therapeutic strategy for rat DO.

Regulation and mechanistic insights into tensile strain in mesenchymal stem cell osteogenic differentiation.

Bone marrow mesenchymal stem cells (BMSCs) are integral to bone remodeling and homeostasis, as they are capable of differentiating into osteogenic and adipogenic lineages. This differentiation is substantially influenced by mechanosensitivity, particularly to tensile strain, which is a prevalent mechanical stimulus known to enhance osteogenic differentiation. This review specifically examines the effects of various cyclic tensile stress (CTS) conditions on BMSC osteogenesis. It delves into the effects of different loading devices, magnitudes, frequencies, elongation levels, dimensionalities, and coculture conditions, providing a comparative analysis that aids identification of the most conducive parameters for the osteogenic differentiation of BMSCs. Subsequently, this review delineates the signaling pathways activated by CTS, such as Wnt/ß-catenin, BMP, Notch, MAPK, PI3K/Akt, and Hedgehog, which are instrumental in mediating the osteogenic differentiation of BMSCs. Through a detailed examination of these pathways, this study elucidates the intricate mechanisms whereby tensile strain promotes osteogenic differentiation, offering valuable guidance for optimizing therapeutic strategies aimed at enhancing bone regeneration.

BMSC loaded photo-crosslinked hyaluronic acid/collagen hydrogel incorporating FG4592 for enhanced cell proliferation and nucleus pulposus differentiation.

Intervertebral disc degeneration arises from damage or degeneration of the nucleus pulposus (NP). In this study, we developed a photo-crosslinkable hydrogel incorporating FG4592 to support the growth and differentiation of bone-marrow-derived mesenchymal stem cells (BMSC). Initially, hyaluronic acid was modified with tyramine and combined with collagen to introduce riboflavin as a photo-crosslinker. This hydrogel transitioned from liquid to gel upon exposure to blue light in 3 min. The results showed that the hydrogel was biodegradable and had mechanical properties comparable to those of human NP tissues. Scanning electron microscopy after BMSC seeding in the hydrogel revealed an even distribution, and cells adhered to the collagen fibers in the hydrogel with minimal cell mortality. The effect of FG4592 on BMSC proliferation and differentiation was examined, revealing the capability of FG4592 to promote BMSC proliferation and direct differentiation resembling human NP cells. After cultivating BMSCs in the photo-crosslinked hydrogel, there was an upregulation in the expression of glycosaminoglycans, aggrecan, type II collagen, and keratin 19 proteins. Cross-species analyses of rat and human BMSCs revealed consistent results. For potential clinical applications, BMSC loaded with photo-crosslinked hydrogels can be injected into damaged intervertebral disc to facilitate NP regeneration.

Photobiomodulation and mesenchymal stem cell-conditioned medium for the repair of experimental critical-size defects.

Orthopedic surgeons face a significant challenge in treating critical-size femoral defects (CSFD) caused by osteoporosis (OP), trauma, infection, or bone tumor resections. In this study for the first time, the application of photobiomodulation (PBM) and bone marrow mesenchymal stem cell-conditioned medium (BM-MSC-CM) to improve the osteogenic characteristics of mineralized bone scaffold (MBS) in ovariectomy-induced osteoporotic (OVX) rats with a CSFD was tested. Five groups of OVX rats with CSFD were created: (1) Control (C); (2) MBS; (3) MBS + CM; (4) MBS + PBM; (5) MBS + CM + PBM. Computed tomography scans (CT scans), compression indentation tests, and histological and stereological analyses were carried out after euthanasia at 12 weeks following implantation surgery. The CT scan results showed that CSFD in the MBS + CM, MBS + PBM, and MBS + CM + PBM groups was significantly smaller compared to the control group (p = 0.01, p = 0.04, and p = 0.000, respectively). Moreover, the CSFD size was substantially smaller in the MBS + CM + PBM treatment group than in the MBS, MBS + CM, and MBS + PBM treatment groups (p = 0.004, p = 0.04, and p = 0.01, respectively). The MBS + PBM and MBS + CM + PBM treatments had significantly increased maximum force relative to the control group (p = 0.01 and p = 0.03, respectively). Bending stiffness significantly increased in MBS (p = 0.006), MBS + CM, MBS + PBM, and MBS + CM + PBM treatments (all p = 0.004) relative to the control group. All treatment groups had considerably higher new trabecular bone volume (NTBV) than the control group (all, p = 0.004). Combined therapies with MBS + PBM and MBS + CM + PBM substantially increased the NTBV relative to the MBS group (all, p = 0.004). The MBS + CM + PBM treatment had a markedly higher NTBV than the MBS + PBM (p = 0.006) and MBS + CM (p = 0.004) treatments. MBS + CM + PBM, MBS + PBM, and MBS + CM treatments significantly accelerated bone regeneration of CSFD in OVX rats. PBM + CM enhanced the osteogenesis of the MBS compared to other treatment groups.

Role of epigenetic regulatory mechanisms in age-related bone homeostasis imbalance.

Alterations to the human organism that are brought about by aging are comprehensive and detrimental. Of these, an imbalance in bone homeostasis is a major outward manifestation of aging. In older adults, the decreased osteogenic activity of bone marrow mesenchymal stem cells and the inhibition of bone marrow mesenchymal stem cell differentiation lead to decreased bone mass, increased risk of fracture, and impaired bone injury healing. In the past decades, numerous studies have reported the epigenetic alterations that occur during aging, such as decreased core histones, altered DNA methylation patterns, and abnormalities in noncoding RNAs, which ultimately lead to genomic abnormalities and affect the expression of downstream signaling osteoporosis treatment and promoter of fracture healing in older adults. The current review summarizes the impact of epigenetic regulation mechanisms on age-related bone homeostasis imbalance.

Bone marrow mesenchymal stem cells-derived exosomal lncRNA GAS5 mitigates heart failure by inhibiting UL3/Hippo pathway-mediated ferroptosis.

BACKGROUND: Exosomes (Exos) are involved in the therapeutic effects of bone marrow mesenchymal stem cells (BMSCs) on heart failure (HF). We investigated the molecular mechanisms underlying the involvement of BMSC-Exos in ferroptosis on HF. METHODS: A rat model of HF and cellular model of hypoxia were established. BMSC-Exos were injected into model rats or co-cultured with model cells. In model rats, the cardiac function (echocardiography), oxidative stress (commercial kits), pathological damage (HE staining), fibrosis (MASSON staining), iron deposition (Prussian blue staining), and cell apoptosis (TUNEL staining) were examined. Viability (cell counting kit-8; CCK-8), cell cycle (flow cytometry), oxidative stress, and Fe2+ levels were detected in the model cells. GAS5, UL3, YAP, and TAZ expression were detected using qRT-PCR, western blotting, and immunohistochemistry analyses. RESULTS: BMSC-Exos restored cardiac function and inhibited oxidative stress, apoptosis, pathological damage, fibrosis, and iron deposition in myocardial tissues of HF rats. In hypoxic cells, BMSC-Exos increased cell viability, decreased the number of G1 phase cells, decreased Fe2+ levels, and inhibited oxidative stress. Ferrostatin-1 (a ferroptosis inhibitor) exhibited a synergistic effect with BMSC-Exos. Additionally, GAS5 was upregulated in BMSC-Exos, further upregulating its target UL3 and Hippo pathway effectors (YAP and TAZ). The relieving effects of BMSC-Exos on HF or hypoxia-induced injury were enhanced by GAS5 overexpression, but weakened by UL3 silencing or verteporfin (a YAP inhibitor). CONCLUSIONS: GAS5-harbouring BMSC-Exos inhibited ferroptosis by regulating the UL3/Hippo pathway, contributing to HF remission in vivo and in vitro.

Ganoderma spore lipid ameliorates docetaxel, cisplatin, and 5-fluorouracil chemotherapy-induced damage to bone marrow mesenchymal stem cells and hematopoiesis.

BACKGROUND: A triplet chemotherapy regimen of docetaxel, cisplatin, and 5-fluorouracil (TPF) is used to treat head and neck squamous cell carcinoma; however, it is toxic to bone marrow mesenchymal stem cells (BMSCs). We previously demonstrated that Ganoderma spore lipid (GSL) protect BMSCs against cyclophosphamide toxicity. In this study, we investigated the protective effects of GSL against TPF-induced BMSCs and hematopoietic damage. METHODS: BMSCs and C57BL/6 mice were divided into control, TPF, co-treatment (simultaneously treated with GSL and TPF for 2 days), and pre-treatment (treated with GSL for 7 days before 2 days of TPF treatment) groups. In vitro, morphology, phenotype, proliferation, senescence, apoptosis, reactive oxygen species (ROS), and differentiation of BMSCs were evaluated. In vivo, peripheral platelets (PLTs) and white blood cells (WBCs) from mouse venous blood were quantified. Bone marrow cells were isolated for hematopoietic colony-forming examination. RESULTS: In vitro, GSL significantly alleviated TPF-induced damage to BMSCs compared with the TPF group, recovering their morphology, phenotype, proliferation, and differentiation capacity (p < 0.05). Annexin V/PI and senescence-associated ß-galactosidase staining showed that GSL inhibited apoptosis and delayed senescence in TPF-treated BMSCs (p < 0.05). GSL downregulated the expression of caspase-3 and reduced ROS formation (p < 0.05). In vivo, GSL restored the number of peripheral PLTs and WBCs and protected the colony-forming capacity of bone marrow cells (p < 0.05). CONCLUSIONS: GSL efficiently protected BMSCs from damage caused by TPF and recovered hematopoiesis.

[Screening and Identification of lncRNA Related to Adipocity of Bone Marrow Microenvironment in Aplastic Anemia].

OBJECTIVE: To systematically screen and identify long noncoding RNA (lncRNA) associated with bone marrow adiposity changes in aplastic anemia (AA). METHODS: The PPARγ and C/EBPα ChIP-Seq data in ChIPBase was analyzed by bioinformatics and the potential lncRNA co-transcriptionally regulated by PPARγ and C/EBPα was screened. The expression of candidate lncRNA was verified by qRT-PCR in the in vitro adipogenic differentiation model of BM-MSC, BM-MSC infected with lenti-shPPARγ and lenti-shC/EBPα as well as clinical BM-MSC samples derived from AA and controls. RESULTS: PPARγ and C/EBPα were significantly highly expressed in AA BM-MSC, and knock-down of PPARγ and C/EBPα impaired the adipogenic capacity of AA BM-MSC. PPARγ and C/EBPα cotranscriptionally activate LINC01230 promoter activity in binding sites dependant manner. The LINC01230 was also aberrantly highly expressed in AA BM-MSC compared with controls. CONCLUSION: PPARγ and C/EBPα are aberrantly expressed in AA BM-MSC and may promote the adipogenic differentiation of AA BM-MSC, and to a certain extent mediate the bone marrow adiposity alteration by transcriptionally activating LINC01230 expression.

BMSC-derived Exosomes Ameliorate Peritoneal Dialysis-associated Peritoneal Fibrosis via the Mir-27a-3p/TP53 Pathway.

OBJECTIVE: Peritoneal fibrosis (PF) is the main cause of declining efficiency and ultrafiltration failure of the peritoneum, which restricts the long-term application of peritoneal dialysis (PD). This study aimed to investigate the therapeutic effects and mechanisms of bone marrow mesenchymal stem cells-derived exosomes (BMSC-Exos) on PF in response to PD. METHODS: Small RNA sequencing analysis of BMSC-Exos was performed by second-generation sequencing. C57BL/6J mice were infused with 4.25% glucose-based peritoneal dialysis fluid (PDF) for 6 consecutive weeks to establish a PF model. A total of 36 mice were randomly divided into 6 groups: control group, 1.5% PDF group, 2.5% PDF group, 4.25% PDF group, BMSC-Exos treatment group, and BMSC-Exos+TP53 treatment group. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed to measure the expression level of miR-27a-3p in BMSC-Exos and peritoneum of mice treated with different concentrations of PDF. HE and Masson staining were performed to evaluate the extent of PF. The therapeutic potential of BMSC-Exos for PF was examined through pathological examination, RT-qPCR, Western blotting, and peritoneal function analyses. Epithelial-mesenchymal transition (EMT) of HMrSV5 was induced with 4.25% PDF. Cells were divided into control group, 4.25% PDF group, BMSC-Exos treatment group, and BMSC-Exos+TP53 treatment group. Cell Counting Kit-8 assay was used to measure cell viability, and transwell migration assay was used to verify the capacity of BMSC-Exos to inhibit EMT in HMrSV5 cells. RESULTS: Small RNA sequencing analysis showed that miR-27a-3p was highly expressed in BMSC-derived exosomes compared to BMSCs. The RT-qPCR results showed that the expression of miR-27a-3p was upregulated in BMSC-Exos, but decreased in PD mice. We found that PF was glucose concentration-dependently enhanced in the peritoneum of the PD mice. Compared with the control mice, the PD mice showed high solute transport and decreased ultrafiltration volume as well as an obvious fibroproliferative response, with markedly increased peritoneal thickness and higher expression of α-SMA, collagen-I, fibronectin, and ECM1. The mice with PD showed decreased miR-27a-3p. Peritoneal structural and functional damage was significantly attenuated after BMSC-Exos treatment, while PF and mesothelial damage were significantly ameliorated. Additionally, markers of fibrosis (α-SMA, collagen-I, fibronectin, ECM1) and profibrotic cytokines (TGF-ß1, PDGF) were downregulated at the mRNA and protein levels after BMSC-Exos treatment. In HMrSV5 cells, BMSC-Exos reversed the decrease in cell viability and the increase in cell migratory capacity caused by high-glucose PDF. Western blotting and RT-qPCR analysis revealed that BMSC-Exos treatment resulted in increased expression of E-cadherin (epithelial marker) and decreased expression of α-SMA, Snail, and vimentin (mesenchymal markers) compared to those of the 4.25% PDF-treated cells. Importantly, a dual-luciferase reporter assay showed that TP53 was a target gene of miR-27a-3p. TP53 overexpression significantly reversed the decreases in PF and EMT progression induced by BMSC-Exos. CONCLUSION: The present results demonstrate that BMSC-Exos showed an obvious protective effect on PD-related PF and suggest that BMSC-derived exosomal miR-27a-3p may exert its inhibitory effect on PF and EMT progression by targeting TP53.

Collagen sponge scaffolds loaded with Trichostatin A pretreated BMSCs-derived exosomes regulate macrophage polarization to promote skin wound healing.

The process of wound healing includes the inflammatory stage, which plays an important role. Macrophages can promote inflammatory response and also promote angiogenesis, wound contraction and tissue remodeling required for wound healing. It is crucial to promote macrophages to polarize from M1 pro-inflammatory phenotype to M2 anti-inflammatory phenotype at a critical time for the quality of wound healing. Because mesenchymal stem cell-derived exosomes have broad therapeutic prospects in the field of tissue repair and regeneration, in this study, we explored whether trichostatin A pretreated bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (T-Exo) could promote wound healing by binding to biomaterial scaffolds through certain anti-inflammatory effects. In the cell experiment, we established macrophage inflammation model and then treated with T-Exo, and finally detected the expression levels of macrophage polarization proteins CD206, CD86 and TNF-α, iNOS, and Arg-1 by Western Blot and immunofluorescence staining; detected the expression levels of inflammation-related genes TNF-α, iNOS, IL-1ß, IL-10 and anti-inflammatory genes CD206 and Arg-1 by qRT-PCR; explored the promoting ability of T-Exo to promote cell migration and tube formation by cell scratch experiment and angiogenesis experiment. The results showed that T-Exo could promote the polarization of M1 macrophages to M2 macrophages, and promote the migration and angiogenesis of HUVECs. Because TSA pretreatment may bring about changes in the content and function of BMSCs-derived exosomes, proteomic analysis was performed on T-Exo and unpretreated BMSCs-derived exosomes (Exo). The results showed that the differentially expressed proteins in T-Exo were related to some pathways that promote angiogenesis, cell migration, proliferation, and re-epithelialization. Then, exosome/collagen sponge (T-Exo/Col) biological scaffolds were prepared, and the physicochemical properties and biocompatibility of the scaffolds were investigated. Animal skin wound models were established, and the therapeutic effect and anti-inflammatory effect of T-Exo/Col in wound repair were evaluated by small animal in vivo imaging, H&E staining, Masson trichrome staining, immunohistochemical staining, Western Blot, and qRT-PCR. The results showed that T-Exo significantly promoted wound healing by inhibiting inflammation, thereby further promoting angiogenesis and collagen formation in vivo. Moreover, the existence of Col scaffold in T-Exo/Col enabled T-Exo to achieve a certain sustained release effect. Finally, we further explored whether TSA exerts beneficial effects by inhibiting HDAC6 gene of BMSCs, but the results showed that knockdown of HDAC6 gene would cause oxidative stress damage to BMSCs, which means that TSA does not produce these beneficial effects by inhibiting HDAC6 gene. What molecular mechanisms TSA exerts beneficial effects through needs to be further elucidated in the future.

Plasma exosomal miR-30a-5p inhibits osteogenic differentiation of bone marrow mesenchymal stem cells from a chronic unpredictable mild stress-induced depression rat model.

With rising society stress, depression-induced osteoporosis is increasing. However, the mechanism involved is unclear. In this study, we explored the effect of plasma exosomal miRNAs on bone marrow mesenchymal stem cell (BMSC) osteogenic differentiation in a chronic unpredictable mild stress (CUMS)-induced depression rat model. After 12 weeks of CUMS-induced depression, the pathological changes in the bone tissue and markers of osteogenic differentiation were tested by micro-computed tomography, hematoxylin-eosin staining, and quantitative real-time reverse transcription PCR (qRT-PCR). Plasma exosomes from rats were isolated and co-incubated with BMSCs for 14 d to detect the effect on osteogenic markers. Next-generation sequencing identified the miRNAs in the plasma exosomes, and the differential miRNAs were analyzed and verified by qRT-PCR. BMSCs were infected with lentivirus to upregulate miRNA-30a-5p and incubated in a medium that induced osteogenic differentiation for 14 d. The effect of miR-30a-5p on osteogenic differentiation was determined by qPCR and alizarin red staining. CUMS-induced depression rat model was established successfully, and exhibited reduced bone mass and damaged bone microstructure compared to that of the controls. The observed pathological changes suggested the occurrence of osteoporosis in the CUMS group, and the mRNA expression of osteogenic markers was also significantly reduced. Incubation of BMSCs with plasma exosomes from the CUMS group for 14 d resulted in a significant decrease in the expression of osteogenic markers. Twenty-five differentially expressed miRNAs in plasma exosomes were identified and upregulation of miR-30a-5p was observed to significantly inhibit the expression of osteogenic markers in BMSCs. Our findings contributed to a comprehensive understanding of the mechanism of osteoporosis caused by depression, and demonstrated the potential of miR-30a-5p as a novel biomarker or therapeutic target for the treatment of osteoporosis.

Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Promote the Recovery of Spinal Cord Injury and Inhibit Ferroptosis by Inactivating IL-17 Pathway.

Mesenchymal stem cell (MSC)-derived exosomes are considered as alternative to cell therapy in various diseases. This study aimed to understand the effect of bone marrow MSC-derived exosomes (BMMSC-exos) on spinal cord injury (SCI) and to unveil its regulatory mechanism on ferroptosis. Exosomes were isolated from BMMSCs and the uptake of BMMSCs-exos by PC12 cells was determined using PKH67 staining. The effect of BMMSC-exos on SCI in rats was studied by evaluating pathological changes of spinal cord tissues, inflammatory cytokines, and ferroptosis-related proteins. Transcriptome sequencing was used to discover the differential expressed genes (DEGs) between SCI rats and BMMSC-exos-treated rats followed by functional enrichment analyses. The effect of BMMSC-exos on ferroptosis and interleukin 17 (IL-17) pathway was evaluated in SCI rats and oxygen-glucose deprivation (OGD)-treated PC12 cells. The results showed that particles extracted from BMMSCs were exosomes that could be taken up by PC12 cells. BMMSC-exos treatment ameliorated injuries of spinal cord, suppressed the accumulation of Fe2+, malondialdehyde (MDA), and reactive oxygen species (ROS), with the elevated glutathione (GSH). Also, BMMSC-exos downregulated the expression of acyl-CoA synthetase long chain family member 4 (ACSL4) and upregulated glutathione peroxidase 4 (GPX4) and cysteine/glutamate antiporter xCT. A total of 110 DEGs were discovered and they were mainly enriched in IL-17 signaling pathway. Further in vitro and in vivo experiments showed that BMMSC-exos inactivated IL-17 pathway. BMMSC-exos promote the recovery of SCI and inhibit ferroptosis by inhibiting the IL-17 pathway, which provides BMMSC-exos as an alternative to the management of SCI.

Phytic acid promotes high glucose-mediated bone marrow mesenchymal stem cells osteogenesis via modulating circEIF4B that sponges miR-186-5p and complexes with IGF2BP3.

Diabetes-related hyperglycemia inhibits bone marrow mesenchymal stem cell (BMSC) function, thereby disrupting osteoblast capacity and bone regeneration. Dietary supplementation with phytic acid (PA), a natural inositol phosphate, has shown promise in preventing osteoporosis and diabetes-related complications. Emerging evidence has suggested that circular (circ)RNAs implicate in the regulation of bone diseases, but their specific regulatory roles in BMSC osteogenesis in hyperglycemic environments remain elucidated. In this study, in virto experiments demonstrated that PA treatment effectively improved the osteogenic capability of high glucose-mediated BMSCs. Differentially expressed circRNAs in PA-induced BMSCs were identified using circRNA microarray analysis. Here, our findings highlight an upregulation of circEIF4B expression in BMSCs stimulated with PA under a high-glucose microenvironment. Further investigations demonstrated that circEIF4B overexpression promoted high glucose-mediated BMSC osteogenesis. In contrast, circEIF4B knockdown exerted the opposite effect. Mechanistically, circEIF4B sequestered microRNA miR-186-5p and triggered osteogenesis enhancement in BMSCs by targeting FOXO1 directly. Furthermore, circEIF4B inhibited the ubiquitin-mediated degradation of IGF2BP3, thereby stabilizing ITGA5 mRNA and promoting BMSC osteogenic differentiation. In vivo experiments, circEIF4B inhibition attenuated the effectiveness of PA treatment in diabetic rats with cranial defects. Collectively, our study identifies PA as a novel positive regulator of BMSC osteogenic differentiation through the circEIF4B/miR-186-5p/FOXO1 and circEIF4B/IGF2BP3/ITGA5 axes, which offers a new strategy for treating high glucose-mediatedBMSCosteogenic dysfunction and delayed bone regeneration in diabetes.

Bone Marrow Mesenchymal Stem Cell-derived Exosomal microRNA- 99b-5p Promotes Cell Growth of High Glucose-treated Human Umbilical Vein Endothelial Cells by Modulating THAP Domain Containing 2 Expression.

INTRODUCTION: Bone marrow mesenchymal stem cell-derived exosomes (BMSC-exos) may function as novel candidates for treating diabetic wounds due to their ability to promote angiogenesis. MATERIALS AND METHODS: This study investigated the effects of BMSC-exos on the growth and metastasis of human umbilical vein endothelial cells (HUVECs) treated with high glucose (HG). The exosomes were separated from BMSCs and identified. The cell phenotype was detected by 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and 5-ethynyl-2'-deoxyuridine, wound healing, and transwell assays, while the number of tubes was measured via tube formation assay. RESULT: The RNA and protein expression levels were studied using reverse transcription-quantitative polymerase chain reaction and western blotting, whereas integration of microRNA-99b-5p (miR-99b-5p) with THAP domain containing 2 (THAP2) was confirmed via dual-luciferase reporter and RNA pull-down assays. Results of transmission electron microscopy, nanoparticle tracking analysis, and laser scanning confocal microscopy revealed that exosomes were successfully separated from BMSCs and endocytosed into the cytoplasm by HUVECs. Similarly, BMSC-exos were found to promote the growth of HG-treated HUVECs, while their growth was inhibited by suppressing miR-99b-5p. THAP2 was found to bind to miR-99b-5p, where THAP2 inhibition reversed the miR-99b-5p-induced effects on cell growth, migration, and tube numbers. CONCLUSION: In conclusion, miR-99b-5p in BMSC-exo protects HUVECs by negatively regulating THAP2 expression.

Exosomes derived from CD271+CD56+ bone marrow mesenchymal stem cell subpopoulation identified by single-cell RNA sequencing promote axon regeneration after spinal cord injury.

Rationale: Spinal cord injury (SCI) results in neural tissue damage. However, the limited regenerative capacity of adult mammals' axons upon SCI leads to persistent neurological dysfunction. Thus, exploring the pathways that can enhance axon regeneration in injured spinal cord is of great significance. Methods: Through the utilization of single-cell RNA sequencing in this research, a distinct subpopulation of bone marrow mesenchymal stem cells (BMSCs) that exhibits the capacity to facilitate axon regeneration has been discovered. Subsequently, the CD271+CD56+ BMSCs subpopulation was isolated using flow cytometry, and the exosomes derived from this subpopulation (CD271+CD56+ BMSC-Exos) were extracted and incorporated into a hydrogel to create a sustained release system. The aim was to investigate the therapeutic effects of CD271+CD56+ BMSC-Exos and elucidate the underlying mechanisms involved in promoting axon regeneration and neural function recovery. Results: The findings indicate that CD271+CD56+ BMSC-Exos share similar physical and chemical properties with conventional exosomes. Importantly, in an SCI model, in situ implantation of CD271+CD56+ BMSC-Exos hydrogel resulted in increased expression of NF and synaptophysin, markers associated with axon regeneration and synapse formation, respectively. This intervention also contributed to improved neural function recovery. In vitro experiments demonstrated that CD271+CD56+ BMSC-Exos treatment significantly enhanced axon extension distance and increased the number of branches in dorsal root ganglion axons. Moreover, further investigation into the molecular mechanisms underlying CD271+CD56+ BMSC-Exos-mediated axon regeneration revealed the crucial involvement of the miR-431-3p/RGMA axis. Conclusion: In summary, the implantation of CD271+CD56+ BMSC-Exos hydrogel presents a promising and effective therapeutic approach for SCI.

Exosomal miR-4645-5p from hypoxic bone marrow mesenchymal stem cells facilitates diabetic wound healing by restoring keratinocyte autophagy.

Background: Refractory diabetic wounds are a common occurrence in patients with diabetes and epidermis-specific macroautophagy/autophagy impairment has been implicated in their pathogenesis. Therefore, identifying and developing treatment strategies capable of normalizing epidermis-specific macroautophagy/autophagy could facilitate diabetic wound healing. The study aims to investigate the potential of bone marrow mesenchymal stem cell-derived exosomes (BMSC-exos) from hypoxic conditions as a treatment to normalize epidermis-specific autophagy for diabetic wound healing. Methods: We compared the effects of bone marrow mesenchymal stem cell (BMSC)-sourced exosomes (BMSC-Exos) from hypoxic conditions to those of BMSC in normoxic conditions (noBMSC-Exos). Our studies involved morphometric assessment of the exosomes, identification of the microRNA (miRNA) responsible for the effects, evaluation of keratinocyte functions and examination of effects of the exosomes on several molecules involved in the autophagy pathway such as microtubule-associated protein 1 light chain 3 beta, beclin 1, sequestosome 1, autophagy-related 5 and autophagy-related 5. The experiments used human BMSCs from the American Type Culture Collection, an in vivo mouse model of diabetes (db/db) to assess wound healing, as well as the human keratinocyte HaCaT cell line. In the methodology, the authors utilized an array of approaches that included electron microscopy, small interfering RNA (siRNA) studies, RNA in situ hybridization, quantitative real-time reverse transcription PCR (qRT-PCR), the isolation, sequencing and differential expression of miRNAs, as well as the use of miR-4645-5p-specific knockdown with an inhibitor. Results: Hypoxia affected the release of exosomes from hypoxic BMSCs (hy-BMSCs) and influenced the size and morphology of the exosomes. Moreover, hyBMSC-Exo treatment markedly improved keratinocyte function, including keratinocyte autophagy, proliferation and migration. miRNA microarray and bioinformatics analysis showed that the target genes of the differentially expressed miRNAs were mainly enriched in 'autophagy' and 'process utilizing autophagic mechanism' in the 'biological process' category and miR-4645-5p as a major contributor to the pro-autophagy effect of hyBMSC-Exos. Moreover, mitogen-activated protein kinase-activated protein kinase 2 (MAPKAPK2) was identified as a potential target of exosomal miR-4645-5p; this was confirmed using a dual luciferase assay. Exosomal miR-4645-5p mediates the inactivation of the MAPKAPK2-induced AKT kinase group (comprising AKT1, AKT2, and AKT3), which in turn suppresses AKT-mTORC1 signaling, thereby facilitating miR-4645-5p-mediated autophagy. Conclusions: Overall, the results of this study showed that hyBMSC-Exo-mediated transfer of miR-4645-5p inactivated MAPKAPK2-induced AKT-mTORC1 signaling in keratinocytes, which activated keratinocyte autophagy, proliferation and migration, resulting in diabetic wound healing in mice. Collectively, the findings could aid in the development of a novel therapeutic strategy for diabetic wounds.

Overexpression of lncRNA LINC00665 inhibits the proliferation and chondroblast differentiation of bone marrow mesenchymal stem cells by targeting miR-214-3p.

BACKGROUND: Osteoarthritis is a chronic disease mainly involving the damage of articular cartilage and the whole articular tissue, which is the main cause of disability in the elderly. To explore more effective treatment measures, this study analyzed the regulatory role and molecular mechanism of lncRNA LINC00665 (LINC00665) in the chondrogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), providing a valuable theoretical basis for the pathogenesis and patient treatment of osteoarthritis. METHODS: Osteoarthritis tissues and healthy tissues were obtained from 52 patients with osteoarthritis and 34 amputated patients without osteoarthritis, and the levels of LINC00665 and miR-214-3p were assessed by RT-qPCR. BMSCs were cultured and induced chondrogenic differentiation. The proliferation ability of BMSCs was detected by CCK-8 method, and the apoptosis level of BMSCs was evaluated by flow cytometry. The content of proteoglycan-glycosaminoglycan (GAG) in cartilage matrix was determined by Alcian blue staining. In addition, the binding relationship between LINC00665 and miR-214-3p was verified by luciferase reporter assay, and the molecular mechanism was further analyzed. RESULTS: In osteoarthritis tissues, LINC00665 was elevated and miR-214-3p was down-regulated. With the chondrogenic differentiation of BMSCs, the level of GAG increased, and LINC00665 expression gradually decreased, while miR-214-3p level was on the contrary. After transfection of pcDNA3.1-LINC00665 in BMSCs, cell proliferation capacity was decreased, apoptosis rate was increased, and GAG content was reduced. Moreover, LINC00665 sponged miR-214-3p and negatively regulate its expression. Transfection of pcDNA3.1-LINC00665-miR-214-3p mimic changed the regulation of pcDNA3.1-LINC00665 on the viability and chondrogenic differentiation of BMSCs. CONCLUSIONS: Overexpression of lncRNA LINC00665 inhibited the proliferation and chondrogenic differentiation of BMSCs by targeting miR-214-3p. The LINC00665/miR-214-3p axis may improve joint damage and alleviate the progression of osteoarthritis.

BMSC-derived exosomal miR-148b-3p attenuates OGD/R-induced HMC3 cell activation by targeting DLL4 and Notch1.

Bone mesenchymal stem cell (BMSC)-derived exosome (BMSC-Exo) could be a treatment method for ischemic injury. In ischemic cerebrovascular disease (IC), microglia is pivotal in neuronal damage and remodeling. This study explores the mechanisms of BMSC-Exo miR-148b-3p in regulating oxygen-glucose deprivation/reoxygenation (OGD/R)-induced human microglial clone 3 (HMC3) cell activation. Transmission electron microscopy (TEM) and qNano were used to assess BMSC-Exo features. The functions of BMSC-Exo miR-148 b-3p in OGD/R-induced HMC3 cell activation were explored via MTT assay, flow cytometry, scratch, transwell, and enzyme-linked immunosorbent assay (ELISA) assays. A dual-luciferase reporter assay was performed to determine the relationship between miR-148b-3p and Delta-like ligand 4(DDL4) or neurogenic locus notch homolog protein 1 (Notch1). OGD/R decreased miR-148b-3p expression in HMC3 cells. After BMSC-Exo treatment, miR-148b-3p expression was upregulated, cell viability and migration were inhibited, cell cycles remained in the G0/G1 phase, and proinflammatory cytokines were decreased in OGD/R-induced HMC3 cells. More importantly, BMSC-Exo miR-148b-3p could further strengthen BMSC-Exo effects. DDL4 and Notch1 are direct targets of miR-148b-3p, respectively. Moreover, the knockdown of DLL4 or Notch1 could inhibit OGD/R-induced HMC3 cell activation. BMSC-Exo miR-148b-3p inhibited OGD/R-induced HMC3 cell activation via inhibiting DLL4 and Notch1 expression, which provided a new strategy for treating cerebral ischemia.