Mesenchymal Stem Cell-derived Exosomes Research Articles

Effect of pulsed electromagnetic fields on mesenchymal stem cell-derived exosomes in inhibiting chondrocyte apoptosis

The study aims to explore the effect of mesenchymal stem cells-derived exosomes (MSCs-Exo) on staurosporine (STS)-induced chondrocyte apoptosis before and after exposure to pulsed electromagnetic field (PEMF) at different frequencies. The AMSCs were extracted from the epididymal fat of healthy rats before and after exposure to the PEMF at 1 mT amplitude and a frequency of 15, 45, and 75 Hz, respectively, in an incubator. MSCs-Exo was extracted and identified. Exosomes were labeled with DiO fluorescent dye, and then co-cultured with STS-induced chondrocytes for 24 h. Cellular uptake of MSC-Exo, apoptosis, and the protein and mRNA expression of aggrecan, caspase-3 and collagenⅡA in chondrocytes were observed. The study demonstrated that the exposure of 75 Hz PEMF was superior to 15 and 45 Hz PEMF in enhancing the effect of exosomes in alleviating chondrocyte apoptosis and promoting cell matrix synthesis. This study lays a foundation for the regulatory mechanism of PEMF stimulation on MSCs-Exo in inhibiting chondrocyte apoptosis, and opens up a new direction for the prevention and treatment of osteoarthritis.

Human Pluripotent Stem Cell-Mesenchymal Stem Cell-Derived Exosomes Promote Ovarian Granulosa Cell Proliferation and Attenuate Cell Apoptosis Induced by Cyclophosphamide in a POI-like Mouse Model.

Premature ovarian insufficiency (POI) is a complex disease which causes amenorrhea, hypergonadotropism and infertility in patients no more than 40 years old. Recently, several studies have reported that exosomes have the potential to protect ovarian function using a POI-like mouse model induced by chemotherapy drugs. In this study, the therapeutic potential of exosomes derived from human pluripotent stem cell-mesenchymal stem cells (hiMSC exosomes) was evaluated through a cyclophosphamide (CTX)-induced POI-like mouse model. POI-like pathological changes in mice were determined by serum sex-hormones levels and the available number of ovarian follicles. The expression levels of cellular proliferation proteins and apoptosis-related proteins in mouse ovarian granulosa cells were measured using immunofluorescence, immunohistochemistry and Western blotting. Notably, a positive effect on the preservation of ovarian function was evidenced, since the loss of follicles in the POI-like mouse ovaries was slowed. Additionally, hiMSC exosomes not only restored the levels of serum sex hormones, but also significantly promoted the proliferation of granulosa cells and inhibited cell apoptosis. The current study suggests that the administration of hiMSC exosomes in the ovaries can preserve female-mouse fertility.

Bone marrow mesenchymal stem cell-derived exosomes attenuate the maturation of dendritic cells and reduce the rejection of allogeneic transplantation

Bone marrow mesenchymal stem cell-derived exosomes attenuate the maturation of dendritic cells and reduce the rejection of allogeneic transplantation

Ginkgolide A improves the pleiotropic function and reinforces the neuroprotective effects by mesenchymal stem cell-derived exosomes in 6-OHDA-induced cell model of Parkinson's disease.

Parkinson's disease (PD) is a common disorder attributed to the loss of midbrain dopamine (mDA) neurons and reduced dopamine secretion. Currently, the treatment regimes for PD comprise deep brain stimulations, however, it attenuates the PD progression marginally and does not improve neuronal cell death. We investigated the function of Ginkgolide A (GA) to reinforce Wharton's Jelly-derived mesenchymal stem cells (WJMSCs) for treating the in vitro model of PD. GA enhanced the self-renewal, proliferation, and cell homing function of WJMSCs as assessed by MTT and transwell co-culture assay with a neuroblastoma cell line. GA pre-treated WJMSCs can restore 6-hydroxydopamine (6-OHDA)-induced cell death in a co-culture assay. Furthermore, exosomes isolated from GA pre-treated WJMSCs significantly rescued 6-OHDA-induced cell death as determined by MTT assay, flow cytometry, and TUNEL assay. Western blotting showed that apoptosis-related proteins were decreased following GA-WJMSCs exosomal treatment which further improved mitochondrial dysfunction. We further demonstrated that exosomes isolated from GA-WJMSCs could restore autophagy using immunofluorescence staining and immunoblotting assay. Finally, we used the alpha-synuclein recombinant protein and found that exosomes derived from GA-WJMSCs led to the reduced aggregation of alpha-synuclein compared to that in control. Our results suggested that GA could be a potential candidate for strengthening stem cell and exosome therapy for PD.

Exosomes rich in Wnt5 improved circadian rhythm dysfunction via enhanced PPARγ activity in the 6-hydroxydopamine model of Parkinson's disease

Sleep disorder is one of the most common non-motor symptoms in Parkinson's disease (PD) and even appear as early symptoms. Here we investigated the therapeutic potential of mesenchymal stem cell-derived exosomes (MSC-EXOs) on sleep disorder in PD rats. 6-hydroxydopa (6-OHDA) was used to establish the PD rat model. BMSCquiescent-EXO and BMSCinduced-EXO groups were given intravenous injection 100 µg/g per day for 4 weeks, while control groups were given intravenous injection of the same volume of normal saline. The total sleep time, slow-wave sleep time and fast-wave sleep time in the BMSCquiescent-EXO and BMSCinduced-EXO groups were significantly prolonged (P < 0.05) compared with PD group, while the awakening time was significantly shortened (P < 0.05). In addition, increased levels of dopamine (P < 0.05) and 5-hydroxytryptamine (P < 0.05) levels were observed in the striatum of BMSCquiescent-EXO and BMSCinduced-EXO groups. Further, qPCR and western blot revealed that the mRNA levels of CLOCK, BMAL1 and PER2 in suprachiasmatic nucleus (SCN) were notably increased in BMSCquiescent-EXO and BMSCinduced-EXO groups compared to those from PD rats. More importantly, peroxisome proliferation-activated receptor γ (PPARγ) activities were significantly enhanced after treatment with BMSCquiescent-EXO and BMSCinduced-EXO. JC-1 fluorescence staining showed that mitochondrial membrane potential imbalance was repaired after inoculation of BMSCinduced-EXO. In summary, MSC-EXOs showed the improvement of sleep disorder in PD rats through recovering circadian rhythm associated gene expression. The potential mechanisms may be related with increased PPARγ activities and rescued mitochondrial membrane potential imbalance in Parkinson striatum.

Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Alleviate Peritoneal Dialysis-Associated Peritoneal Injury.

Peritoneal fibrosis is a critical sequela that limits the application of peritoneal dialysis (PD). This study explored the role and mechanism of bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) in preventing PD-associated peritoneal injury. C57BL/6 mice were randomized into three groups: a control (saline), peritoneal injury [2.5% glucose peritoneal dialysate + lipopolysaccharide (LPS)], and peritoneal injury + exosome group. After 6 weeks, mice were dissected, and the parietal peritoneum was collected. The level of peritoneal structural and functional damage was assessed. Additionally, transcriptome analysis of the peritoneum and miRNA sequencing on BMSC-Exos were performed. The parietal peritoneum had significantly thickened, and peritoneal function was impaired in the peritoneal injury group. Peritoneal structural and functional damage was significantly reduced after exosome treatment, while peritoneal inflammation, fibrosis, angiogenesis, and mesothelial damage significantly increased. Transcriptomic analysis showed that the BMSC-Exos affected the cell cycle process, cell differentiation, and inflammatory response regulation. Significant pathways in the exosome group were enriched by inflammation, immune response, and cell differentiation, which constitute a molecular network that regulates the peritoneal protective mechanism. Additionally, inflammatory factors (TNF-α, IL-1β), fibrosis markers (α-SMA, collagen-III, fibronectin), profibrotic cytokines (TGF-β1), and angiogenesis-related factor (VEGF) were downregulated at the mRNA and protein levels through BMSC-Exos treatment. BMSC-Exos treatment can prevent peritoneal injury by inhibiting peritoneal fibrosis, inflammation, and angiogenesis, showing a multitarget regulatory effect. Therefore, BMSC-Exos therapy might be a new therapeutic strategy for treating peritoneal injury.

HucMSC-Ex Alleviates IBD-Associated Intestinal Fibrosis by Inhibiting ERK Phosphorylation in Intestinal Fibroblasts.

Intestinal fibrosis, one of the complications of inflammatory bowel disease (IBD), is associated with fistula and intestinal stricture formation. There are currently no treatments for fibrosis. Mesenchymal stem cell-derived exosomes have been proven to exert inhibitory and reversal effects in IBD and other organ fibrosis. In this study, we explored the role of human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-Ex) in IBD-related fibrosis and its associated mechanism to provide new ideas for the prevention and treatment of IBD-related intestinal fibrosis. We established a DSS-induced mouse IBD-related intestinal fibrosis model and observed the effect of hucMSC-Ex on the mouse model. We also used the TGF-induced human intestinal fibroblast CCD-18Co to observe the role of hucMSC-Ex in the proliferation, migration, and activation of intestinal fibroblasts. Having observed that the extracellular-signal-regulated kinase (ERK) pathway in intestinal fibrosis can be inhibited by hucMSC-Ex, we treated intestinal fibroblasts with an ERK inhibitor to emphasize the potential target of ERK phosphorylation in the treatment of IBD-associated intestinal fibrosis. In the animal model of IBD-related fibrosis, hucMSC-Ex alleviated inflammation-related fibrosis as evident in the thinning of the mice's intestinal wall and decreased expression of related molecules. Moreover, hucMSC-Ex inhibited TGF-β-induced proliferation, migration, and activation of human intestinal fibroblasts, and ERK phosphorylation played a key role in IBD-associated fibrosis. The inhibition of ERK decreased the expression of fibrosis-related indicators such as α-SMA, fibronectin, and collagen I. hucMSC-Ex alleviates DSS-induced IBD-related intestinal fibrosis by inhibiting profibrotic molecules and intestinal fibroblast proliferation and migration by decreasing ERK phosphorylation.

Mesenchymal and Neural Stem Cell-Derived Exosomes in Treating Alzheimer's Disease.

As the most common form of dementia and a progressive neurodegenerative disorder, Alzheimer's disease (AD) affects over 10% world population with age 65 and older. The disease is neuropathologically associated with progressive loss of neurons and synapses in specific brain regions, deposition of amyloid plaques and neurofibrillary tangles, neuroinflammation, blood-brain barrier (BBB) breakdown, mitochondrial dysfunction, and oxidative stress. Despite the intensive effort, there is still no cure for the disorder. Stem cell-derived exosomes hold great promise in treating various diseases, including AD, as they contain a variety of anti-apoptotic, anti-inflammatory, and antioxidant components. Moreover, stem cell-derived exosomes also promote neurogenesis and angiogenesis and can repair damaged BBB. In this review, we will first outline the major neuropathological features associated with AD; subsequently, a discussion of stem cells, stem cell-secreted exosomes, and the major exosome isolation methods will follow. We will then summarize the recent data involving the use of mesenchymal stem cell- or neural stem cell-derived exosomes in treating AD. Finally, we will briefly discuss the challenges, perspectives, and clinical trials using stem cell-derived exosomes for AD therapy.

Hair follicle mesenchymal stem cell exosomal lncRNA H19 inhibited NLRP3 pyroptosis to promote diabetic mouse skin wound healing.

Skin wounds caused by diabetes are a major medical problem. Mesenchymal stem cell-derived exosomes hold promise to quicken wound healing due to their ability to transfer certain molecules to target cells, including mRNAs, microRNAs, lncRNAs, and proteins. Nonetheless, the specific mechanisms underlying this impact are not elucidated. Therefore, this research aimed to investigate the effect of MSC-derived exosomes comprising long non-coding RNA (lncRNA) H19 on diabetic skin wound healing. Hair follicle mesenchymal stem cells (HF-MSCs) were effectively isolated and detected, and exosomes (Exo) were also isolated smoothly. Pretreatment with 30 mM glucose for 24 h (HG) could efficiently induce pyroptosis in HaCaT cells. Exosomal H19 enhanced HaCaT proliferation and migration and inhibited pyroptosis by reversing the stimulation of the NLRP3 inflammasome. Injection of exosomes overexpressing lncRNA H19 to diabetic skin wound promoted sustained skin wound healing, whereas sh-H19 exosomes did not have this effect. In conclusion, Exosomes overexpressing H19 promoted HaCaT proliferation, migration and suppressed pyroptosis both in vitro and in vivo. Therefore, HFMSC-derived exosomes that overexpress H19 may be included in strategies for healing diabetic skin wounds.

3D bioprinting of dECM/Gel/QCS/nHAp hybrid scaffolds laden with mesenchymal stem cell-derived exosomes to improve angiogenesis and osteogenesis

Craniofacial bone regeneration is a coupled process of angiogenesis and osteogenesis, which, associated with infection, still remains a challenge in bone defects after trauma or tumor resection. 3D tissue engineering scaffolds with multifunctional-therapeutic properties can offer many advantages for the angiogenesis and osteogenesis of infected bone defects. Hence, in the present study, a microchannel networks-enriched 3D hybrid scaffold composed of decellularized extracellular matrix (dECM), gelatin (Gel), quaterinized chitosan (QCS) and nano-hydroxyapatite (nHAp) (dGQH) was fabricated by an extrusion 3D bioprinting technology. And enlightened by the characteristics of natural bone microstructure and the demands of vascularized bone regeneration, the exosomes (Exos) isolated from human adipose derived stem cells as angiogenic and osteogenic factors were then co-loaded into the desired dGQH20 hybrid scaffold based on an electrostatic interaction. The results of the hybrid scaffolds performance characterization showed that these hybrid scaffolds exhibited an interconnected pore structure and appropriate degradability (>61% after 8 weeks of treatment), and the dGQH20 hybrid scaffold displayed the highest porosity (83.93 ± 7.38%) and mechanical properties (tensile modulus: 62.68 ± 10.29 MPa, compressive modulus: 16.22 ± 3.61 MPa) among the dGQH hybrid scaffolds. Moreover, the dGQH20 hybrid scaffold presented good antibacterial activities (against 94.90 ± 2.44% of Escherichia coli and 95.41 ± 2.65% of Staphylococcus aureus, respectively) as well as excellent hemocompatibility and biocompatibility. Furthermore, the results of applying the Exos to the dGQH20 hybrid scaffold showed that the Exo promoted the cell attachment and proliferation on the scaffold, and also showed a significant increase in osteogenesis and vascularity regeneration in the dGQH@Exo scaffolds in vitro and in vivo. Overall, this novel dECM/Gel/QCS/nHAp hybrid scaffold laden with Exo has a considerable potential application in reservation of craniofacial bone defects.

MAPK/AP-1 Signaling Pathway Is Involved in the Protection Mechanism of Bone Marrow Mesenchymal Stem Cells-Derived Exosomes against Ultraviolet-Induced Photoaging in Human Dermal Fibroblasts

Introduction: The role of bone marrow mesenchymal stem cells-derived exosomes (BMSCs-exo) in skin photoaging was explored in human dermal fibroblasts (HDFs). The underlying mechanism was further explored. Methods: HDFs were exposed to UVB irradiation to establish the cell photodamage models. The cell viability and levels of oxidative stress-related factors were tested. ELISA was done to detect TNF-α, IL-6, and IL-1β concentrations. Western blot was applied for protein examination. Results: UVB treatment led to the inhibition of cell viability. But after BMSCs-exo addition, the inhibitory effect was returned in a dose manner. UVB exposure contributed to the increase of reactive oxygen species and LDH and the downregulation of superoxide dismutase. In addition, excessive secretion of TNF-α, IL-6, and IL-1β was also detected in cells exposed to UVB. However, BMSCs-exo addition eliminated the effects of UVB on oxidative stress and inflammation in HDFs. BMSCs-exo inhibited matrix metalloproteinases MMP-1 and MMP-3 expression but promoted collagen I expression. UVB radiation activated the MAPK/AP-1 signaling, manifested as the increase of p-p38, c-Jun, and c-Fos protein levels, which were reversed by BMSCs-exo. As a p38 agonist, anisomycin counteracted the effect of BMSCs-exo on HDF’s viability, oxidative stress, and inflammation. Conclusion: BMSCs-exo protected HDFs against UVB-induced inhibition of cell viability and the activation of cell oxidative stress and inflammation, which might be related to the inhibition of the MAPK/AP-1 signaling pathway.

Loading Ovalbumin into Mesenchymal Stem Cell-Derived Exosomes as a Nanoscale Carrier with Immunomodulatory Potential for Allergen-Specific Immunotherapy.

Exosomes are nanoscale vesicles widely used as drug delivery systems. Mesenchymal stem cell (MSC)-derived exosomes have shown immunomodulatory potential. This study optimized loading OVA into the mice adipose tissue-derived MSC-isolated exosomes to prepare the OVA-MSC-exosome complex for allergen-specific immunotherapy. MSCs were harvested from mice adipose tissue and characterized by flow cytometry and evaluating differentiation potential. The exosomes were isolated and characterized via Dynamic Light Scattering, Scanning Electron Microscopy, and flow cytometry. Different concentrations of ovalbumin were incubated with MSC-exosome in various durations to optimize a more suitable protocol. BCA and HPLC analysis were used to quantify, and DLS was applied to qualify the prepared formulation of the OVA-exosome complex. The harvested MSCs and isolated exosomes were characterized. Analysis of the OVA-exosome complex revealed that OVA in primary 500 μg/ml concentration and incubation for 6 h results in higher efficacy. Loading OVA into MSC-derived exosomes was successfully optimized and could be administrated for allergen-specific immunotherapy in the animal model.

Oral delivery of layer-by-layer coated exosomes for colitis therapy.

Mesenchymal stem cell-derived exosomes (MSC-Exos) have attracted much attention as a potential cell-free therapy for ulcerative colitis (UC), mainly due to their anti-inflammatory, tissue repair, and immunomodulatory properties. Although intravenous injection of MSC-Exos is able to improve UC to a certain extent, oral administration of exosomes is the preferred method to treat gastrointestinal diseases such as UC. However, exosomes contain proteins and nucleic acids that are vulnerable to degradation by the gastrointestinal environment, making oral administration difficult to implement. Layer-by-layer (LbL) self-assembly technology provides a promising strategy for the oral delivery of exosomes. Therefore, an efficient LbL-Exos self-assembly system was constructed in this study for the oral delivery of exosomes targeted to the colon to improve UC treatment. Biocompatible and biodegradable N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) and oxidized konjac glucomannan (OKGM) polysaccharides were used as the outer layers to provide colon targeting and to protect exosomes from degradation. Similar to plain exosomes, LbL-Exos had a similar structure and features, but LbL provided controlled release of exosomes in the inflammatory colon. Compared with intravenous administration, oral administration of LbL-Exos could effectively alleviate UC using half the number of exosomes. Mechanistic studies showed that LbL-Exos were internalized by macrophages and intestinal epithelial cells to exert anti-inflammatory and tissue repair effects and therefore alleviate UC. Furthermore, the LbL-Exos system was able to improve UC via MAPK/NF-κB signaling pathway inhibition. Overall, our data show that LbL-MSC-Exos can alleviate UC after oral administration and therefore may constitute a new strategy for UC treatment in the future.

Human umbilical cord mesenchymal stem cells-derived exosomal circDLGAP4 promotes angiogenesis after cerebral ischemia-reperfusion injury by regulating miR-320/KLF5 axis.

Accumulating evidence suggests that human umbilical cord mesenchymal stem cell-derived exosomes (hUC-MSCs-Exos) are a promising therapeutic strategy for cerebral ischemia-reperfusion injury (CIRI). However, the underlying mechanism remains unclear. hUC-MSCs-Exos were identified by electron microscopy, NTA, and Western blotting. In the hypoxia/reoxygenation (H/R) cell model, human brain microvascular endothelial cells (HBMECs) were cocultured with hUC-MSCs-Exos. Then, cell viability, migration, apoptosis, and tube formation were measured by MTT, flow cytometry, transwell, and tube formation assays. RT-qPCR and Western blotting were used to detect the changes in RNA and protein. RNA pull-down and dual luciferase reporter assays confirmed the relationship between circDLGAP4, miR-320, and KLF5. Ischemia-reperfusion (I/R) rat model was established for in vivo experiments. hUC-MSCs-Exos increased the expression levels of circDLGAP4 and KLF5 but decreased miR-320 in H/R-treated HBMECs by transferring exosomal circDLGAP4. Knockdown of circDLGAP4 in hUC-MSCs-Exos reversed the promoting effects of hUC-MSCs-Exos on cell viability, migration, and tube formation in H/R-treated HBMECs in vitro and also abolished the protective effects of hUC-MSCs-Exos on cerebrovascular injury in I/R rats. Mechanistically, exosomal circDLGAP4 negatively regulated miR-320 in HBMECs, which directly bound to KLF5. In addition, the downregulation of miR-320 could reverse the regulatory effect of exosomal shcircDLGAL5 in H/R-treated HBMECs by upregulating KLF5. hUC-MSCs-Exos-derived circDLGAP4 reduced cerebrovascular injury by regulating miR-320/KLF5 signaling. These results provide a stem cell-based approach to treat CIRI.

TGF-β1 stimulated mesenchymal stem cells-generated exosomal miR-29a promotes the proliferation, migration and fibrogenesis of tenocytes by targeting FABP3.

Rotator cuff Tear (RCT) causes a lot of inconvenience for patients. In most cases, RCT injury does not heal back to bone after repair, and there is a high chance of retearing. Therefore, there is a need to explore more effective targeted therapies. Bone mesenchymal stem cell-derived exosome (BMSCs-Exo) has been proved to be beneficial to the proliferation of tendon cells, but its specific mechanism remains to be further explored. BMSCs-Exo was isolated and identified by detecting the specific markers using flow cytometry and western blot assays. qRT-PCR and western blot were utilized to determine the gene or protein expressions, respectively. Cell proliferation, and migration in tenocytes were measured by CCK8, EdU and transwell assays. The interaction between miR-29a and FABP3 was analyzed using dual-luciferase reporter assay. Our findings demonstrated that miR-29a was expressed in BMSCs-Exo and could be significantly enriched after TGF-β1 treatment. Moreover, TGF-β1-modified BMSCs-Exo co-cultured could promote the proliferation, migration and fibrosis of tenocytes by carrying miR-29a. Upon miR-29a was reduced in BMSCs-Exo, the regulatory roles of BMSCs-Exo on tenocytes were reversed. Mechanistically, miR-29a negatively regulated FABP3 via interaction with its 3'-UTR. Enforced expression of FABP3 could reverse the modulation of exosomal miR-29a in tenocytes. Exosomal miR-29a derived from TGF-β1-modified BMSCs facilitated the proliferation, migration and fibrosis of tenocytes through targeting FABP3.

Mesenchymal Stem Cell-Derived Exosomes Ameliorate Diabetic Kidney Disease Through the NLRP3 Signaling Pathway.

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease worldwide. Exosomes (Exo) derived from human umbilical cord mesenchymal stem cells (HUC-MSCs) have been demonstrated to be an effective therapy for DKD, but the underlying mechanisms of this action remain poorly defined. We investigated the association of DKD with inflammasome activation and the pathophysiological relevance of Exo-mediated inflammation relief as well as damage repair in this progression. We co-cultured podocytes and HUC-MSCs derived Exo (MSCs-Exo) under high glucose (HG) and injected MSCs-Exo into diabetic mice, then we detected the NLRP3 inflammasome both in vitro and in vivo. We found that HG reduced the viability of podocytes, activated the NLRP3 signaling pathway and increased inflammation in podocytes and diabetic mice. MSCs-Exo attenuated the inflammation, including the expression of IL-6, IL-1β, IL-18, TNF-α; depressed the activation of NLRP3 signaling pathway in podocytes under HG and diabetic mice, ameliorated kidney injury. Furthermore, miR-22-3p, which is relatively highly expressed miRNAs in exosomes of MSCs, may be the key point in this progress, by suppressing the expression of its known target, NLRP3. Knocking down miR-22-3p from MSCs-Exo abolished their anti-inflammation activity and beneficial function both in vitro and in vivo. Collectively, our results have demonstrated that exosomes transferring miR-22-3p protected the podocytes and diabetic mice from inflammation by mediating NLRP3 inflammasome, indicating that MSC-derived exosomes may be a promising therapeutic cell-free strategy for DKD.

Mesenchymal Stem Cell-Derived Exosomes Enhance 3D-Printed Scaffold Functions and Promote Alveolar Bone Defect Repair by Enhancing Angiogenesis.

The reconstruction of severe alveolar bone defects remains a complex and challenging field for clinicians. Three-dimensional-printed scaffolds can adapt precisely to the complicated shape of the bone defects, which is an alternative solution to bone tissue engineering. Our previous study constructed an innovative low-temperature 3D-printed silk fibroin/collagen I/nano-hydroxyapatite (SF/COL-I/nHA) composite scaffold with a stable structure and remarkable biocompatibility. However, the clinical translation of most scaffolds is limited by insufficient angiogenesis and osteogenesis. In this study, we investigated the effects of human umbilical cord mesenchymal-stem-cell-derived exosomes (hUCMSC-Exos) on bone regeneration, especially from the perspective of inducing angiogenesis. HUCMSC-Exos were isolated and characterized. In vitro, the effect of hUCMSC-Exos on the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs) was examined. Moreover, the loading and release of hUCMSC-Exos on 3D-printed SF/COL-I/nHA scaffolds were evaluated. In vivo, hUCMSC-Exos and 3D-printed SF/COL-I/nHA scaffolds were implanted into alveolar bone defects, and bone regeneration and angiogenesis were investigated by micro-CT, HE staining, Masson staining, and immunohistochemical analysis. The results showed that hUCMSC-Exos stimulated HUVEC proliferation, migration, and tube formation in vitro, and the effect increased with increasing exosome concentrations. In vivo, the combination of hUCMSC-Exos and 3D-printed SF/COL-I/nHA scaffolds promoted alveolar bone defect repair by enhancing angiogenesis and osteogenesis. We constructed an elaborate cell-free bone-tissue-engineering system by combining hUCMSC-Exos with 3D-printed SF/COL-I/nHA scaffolds, potentially providing new ideas for treating alveolar bone defects.

Hyaluronan-based hydrogel integrating exosomes for traumatic brain injury repair by promoting angiogenesis and neurogenesis

With wide clinical demands, therapies for traumatic brain injury (TBI) are far from satisfactory. Combining the merits of stem cells but avoiding the risk of immunologic rejection, bone marrow mesenchymal stem cell-derived exosomes (BME) attract increasing interests and have been proved effective for TBI repair by intravenous or in situ injection. However, difficulties in sustained delivery or aggregation in lesion sites remain obstacle to using BME for TBI. Inspired by that hydrogels are promising to bridge the destroyed neural gap and provide neural niches, we raised a novel strategy of incorporating BME into hyaluronan-collagen hydrogel (DHC-BME) to achieve both mimicking of brain matrix and steady release of exosomes, and thus realizing TBI repair. External characterizations proved that the BME and DHC synergistically promoted neural stem cells (NSCs) differentiation into neurons and oligodendrocytes while inhibited astrocytes differentiation. DHC-BME induced angiogenesis and neurogenesis, from endogenous NSC recruitment to neuronal differentiation and vascularization to synergistically promote axonal regeneration, remyelination, synapse formation and even brain structural remodeling, and lastly, neurological functional recovery of TBI.

Human umbilical cord mesenchymal stem cell-derived exosomes carrying miR-1827 downregulate SUCNR1 to inhibit macrophage M2 polarization and prevent colorectal liver metastasis.

microRNA-1827 (miR-1827) is proposed to be enriched in exosomes from mesenchymal stem cells (MSCs-Exos). A recent study has addressed the suppressive effect of exosomes from human umbilical cord mesenchymal stem cells (hUC-MSCs-Exos) on colorectal cancer (CRC) metastasis. Hence, our study aims at investigating whether hUC-MSCs-Exos can modulate the liver metastasis in CRC by mediating miR-1827. Transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) were used to identify hUC-MSCs-Exos. Using gain- and loss-of-function approaches, the expression of miR-1827 and succinate receptor 1 (SUCNR1) was altered. Consequently, the biological functions of CRC cells were assessed by CCK-8 and Transwell assays and macrophage M2 polarization was assayed by flow cytometry. Dual-luciferase reporter assay was applied to clarify interaction between miR-1827 and SUCNR1. CRC cells were incubated with hUC-MSCs-Exos and tumor-bearing mice were injected with hUC-MSCs-Exos to examine the effects on CRC cell growth and metastasis. SUCNR1, lowly expressed in CRC, could promote CRC cell growth and macrophage M2 polarization. miR-1827 could target SUCNR1 and hence suppress the progression and metastasis of CRC. hUC-MSCs-Exos carried miR-1827 to inhibit M2 macrophage polarization by downregulating SUCNR1 expression, and inhibited proliferating, migrating and invading properties of CRC cells. Furthermore, hUC-MSCs-Exos carrying miR-1827 blocked CRC liver metastasis in vivo. These findings indicate hUC-MSCs-Exos as an inhibitor of M2 macrophage polarization and liver metastasis in CRC through inducing miR-1827-targeted inhibition of SUCNR1. This provides a theoretical basis for understanding the mechanisms underlying Exos-based target therapy for CRC.

Bone marrow mesenchymal stem cell-derived exosomal lncRNA KLF3-AS1 stabilizes Sirt1 protein to improve cerebral ischemia/reperfusion injury via miR-206/USP22 axis

BackgroundCerebral ischemia/reperfusion (I/R) is a pathological process that occurs in ischemic stroke. Bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) have been verified to relieve cerebral I/R-induced inflammatory injury. Hence, we intended to clarify the function of BMSC-Exos-delivered lncRNA KLF3-AS1 (BMSC-Exos KLF3-AS1) in neuroprotection and investigated its potential mechanism.MethodsTo mimic cerebral I/R injury in vivo and in vitro, middle cerebral artery occlusion (MCAO) mice model and oxygen–glucose deprivation (OGD) BV-2 cell model were established. BMSC-Exos KLF3-AS1 were administered in MCAO mice or OGD-exposed cells. The modified neurological severity score (mNSS), shuttle box test, and cresyl violet staining were performed to measure the neuroprotective functions, while cell injury was evaluated with MTT, TUNEL and reactive oxygen species (ROS) assays. Targeted genes and proteins were detected using western blot, qRT-PCR, and immunohistochemistry. The molecular interactions were assessed using RNA immunoprecipitation, co-immunoprecipitation and luciferase assays.ResultsBMSC-Exos KLF3-AS1 reduced cerebral infarction and improved neurological function in MCAO mice. Similarly, it also promoted cell viability, suppressed apoptosis, inflammatory injury and ROS production in cells exposed to OGD. BMSC-Exos KLF3-AS1 upregulated the decreased Sirt1 induced by cerebral I/R. Mechanistically, KLF3-AS1 inhibited the ubiquitination of Sirt1 protein through inducing USP22. Additionally, KLF3-AS1 sponged miR-206 to upregulate USP22 expression. Overexpression of miR-206 or silencing of Sirt1 abolished KLF3-AS1-mediated protective effects.ConclusionBMSC-Exos KLF3-AS1 promoted the Sirt1 deubiquitinating to ameliorate cerebral I/R-induced inflammatory injury via KLF3-AS1/miR-206/USP22 network.