Exosomes derived from mesenchymal stem cells inhibit neointimal hyperplasia by activating the Erk1/2 signalling pathway in rats

Orchestration of macrophage polarization dynamics by fibroblast-secreted exosomes during skin wound healing

Macrophages undertake pivotal yet dichotomous functions during skin wound healing, mediating both early pro-inflammatory immune activation and late anti-inflammatory tissue remodeling processes. The timely phenotypic transition of macrophages from inflammatory M1 to pro-resolving M2 activation states is essential for efficient healing. However, the endogenous mechanisms calibrating macrophage polarization in accordance with the evolving tissue milieu remain undefined. Here, we reveal an indispensable immunomodulatory role for fibroblast-secreted exosomes in directing macrophage activation dynamics. Fibroblast exosomes permitted spatiotemporal coordination of macrophage phenotypes independent of direct intercellular contact. Exosomes enhanced macrophage sensitivity to both M1 and M2 polarizing stimuli, yet also accelerated timely switching from M1 to M2 phenotypes. Exosomes inhibition dysregulated macrophage responses resulting in aberrant inflammation and impaired healing, while provision of exogenous fibroblast exosomes corrected defects. Topical application of fibroblast exosomes onto chronic diabetic wounds normalized dysregulated macrophage activation to resolve inflammation and restore productive healing. Our findings elucidate fibroblast-secreted exosomes as remote programmers of macrophage polarization that calibrate immunological transitions essential for tissue repair. Harnessing exosomes represents a previously unreported approach to steer productive macrophage activation states with immense therapeutic potential for promoting healing in chronic inflammatory disorders.

Improved therapeutic effects on vascular intimal hyperplasia by mesenchymal stem cells expressing MIR155HG that function as a ceRNA for microRNA-205

Coronary artery bypass grafting (CABG) is an effective treatment for coronary heart disease, with vascular transplantation as the key procedure. Intimal hyperplasia (IH) gradually leads to vascular stenosis, seriously affecting the curative effect of CABG. Mesenchymal stem cells (MSCs) were used to alleviate IH, but the effect was not satisfactory. This work aimed to investigate whether lncRNA MIR155HG could improve the efficacy of MSCs in the treatment of IH and to elucidate the role of the competing endogenous RNA (ceRNA). The effect of MIR155HG on MSCs function was investigated, while the proteins involved were assessed. IH was detected by HE and Van Gieson staining. miRNAs as the target of lncRNA were selected by bioinformatics analysis. qRT-PCR and dual-luciferase reporter assay were performed to verify the binding sites of lncRNA-miRNA. The apoptosis, Elisa and tube formation assay revealed the effect of ceRNA on the endothelial protection of MIR155HG-MSCs. We observed that MIR155HG improved the effect of MSCs on IH by promoting viability and migration. MIR155HG worked as a sponge for miR-205. MIR155HG/miR-205 significantly improved the function of MSCs, avoiding apoptosis and inducing angiogenesis. The improved therapeutic effects of MSCs on IH might be due to the ceRNA role of MIR155HG/miR-205.

Isoxanthohumol reduces neointimal hyperplasia through the apelin/AKT pathway

The abnormal proliferation, migration, and inflammation of vascular smooth muscle cells (VSMCs) play crucial roles in the development of neointimal hyperplasia and restenosis. Exposure to inflammatory cytokines such as platelet-derived growth factor (PDGF)-BB and tumour necrosis factor-alpha (TNF-α) induces the transformation of contractile VSMCs into abnormal synthetic VSMCs. Isoxanthohumol (IXN) has significant anti-inflammatory, antiproliferative, and antimigratory effects. This study aimed to explore the therapeutic impact and regulatory mechanism of IXN in treating neointimal hyperplasia. The present findings indicate that IXN effectively hinders the abnormal proliferation, migration, and inflammation of VSMCs triggered by PDGF or TNF-α. This inhibition is primarily achieved through the modulation of the apelin/AKT or AKT pathway, respectively. In an in vivo model, IXN effectively reduced neointimal hyperplasia in denuded femoral arteries. These results suggest that IXN holds promise as a potential and innovative therapeutic candidate for the treatment of restenosis.

Decellularized fish swim bladder patch loaded with mesenchymal stem cells inhibits neointimal hyperplasia

We previously showed decellularized fish swim bladder can be used as vascular patch and tube graft in rats, mesenchymal stem cells (MSCs) have showed the capability to inhibit neointimal hyperplasia in different animal models. We hypothesized that decellularized fish swim bladder patch loaded with MSCs (bioinspired patch) can inhibit neointimal hyperplasia in a rat aortic patch angioplasty model. Rat MSCs were grown in vitro and flow cytometry was used to confirm their quality. 3.6 × 10⁵ MSCs were mixed into 100 μl of sodium alginate (SA)/hyaluronic acid (HA) hydrogel, two layers of fish swim bladders (5 mm × 5 mm) were sutured together, bioinspired patch was created by injection of hydrogel with MSCs into the space between two layers of fish swim bladder patches. Decellularized rat thoracic aorta patch was used as control. Patches were harvested at days 1 and 14 after implantation. Samples were examined by histology, immunohistochemistry, and immunofluorescence. The decellularized rat thoracic aorta patch and the fish swim bladder patch had a similar healing process after implantation. The bioinspired patch had a similar structure like native aorta. Bioinspired patch showed a decreased neointimal thickness (p = .0053), fewer macrophages infiltration (p = .0090), and lower proliferation rate (p = .0291) compared to the double layers fish swim bladder patch group. Decellularized fish swim bladder patch loaded with MSCs can inhibit neointimal hyperplasia effectively. Although this is a preliminary animal study, it may have a potential application in large animals or clinical research.

Exosomes Derived from AT2R-Overexpressing BMSC Prevent Restenosis After Carotid Artery Injury by Attenuating the Injury-Induced Neointimal Hyperplasia

Restenosis is a severe complication after percutaneous transluminal coronary angioplasty which limits the long-term efficacy of the intervention. In this study, we investigated the efficiency of exosomes derived from AT2R-overexpressing bone mesenchymal stem cells on the prevention of restenosis after carotid artery injury. Our data showed that AT2R-EXO promoted the proliferation and migration of vascular endothelial cells and maintained the ratio of eNOS/iNOS. On the contrary, AT2R-EXO inhibited the proliferation and migration of vascular smooth muscle cells. In vivo study proved that AT2R-Exo were more effectively accumulated in the injured carotid artery than EXO and Vehicle-EXO controls. AT2R-EXO treatment could improve blood flow of the injured carotid artery site more effectively. Further analysis revealed that AT2REXO prevents restenosis after carotid artery injury by attenuating the injury-induced neointimal hyperplasia. Our study provides a novel and more efficient exosome for the treatment of restenosis diseases after intervention.

The effect of lncRNA MIR155HG-modified MSCs and exosome delivery to synergistically attenuate vein graft intimal hyperplasia

Background

The mesenchymal stem cells (MSCs) were used to repair tissue injury. However, the treatment effect was not satisfactory. We investigated whether lncRNA MIR155HG could promote survival and migration of MSCs under oxidative stress, which mimics in vivo environments. Furthermore, we studied the protective effect of exosomes secreted by MSCs transfected with MIR155HG on endothelial cells. This study aimed to determine whether exploiting MSCs and exosomes modified with lncRNA MIR155HG would exert synergistic therapeutic effect to attenuate vein graft intimal hyperplasia more effectively.

Methods

Lentivirus containing lncRNA MIR155HG overexpressing vector was packaged and used to infect MSCs. Then, CCK-8 assay, flow cytometry, Transwell assay, and Elisa assay were used to assess the functional changes of MSCs with overexpressed MIR155HG (OE-MSCs). Furthermore, the associated pathways were screened by Western blot. MIR155HG-MSCs-derived exosomes (OE-exo) were collected and co-cultured with human umbilicus vein endothelial cell (HUVEC). We validated the protective effect of OE-exo on HUVEC. In vivo, both MSCs and exosomes modified with MIR155HG were injected into a vein graft rat model via tail vein. We observed MSCs homing and intimal hyperplasia of vein graft using a fluorescent microscope and histological stain.

Results

Our study found that lncRNA MIR155HG promoted proliferation, migration, and anti-apoptosis of MSCs. NF-κB pathway took part in the regulation process induced by MIR155HG. OE-exo could enhance the activity and healing ability of HUVEC and reduce apoptosis. In vivo, OE-MSCs had a higher rate of homing to vascular endothelium. The combined treatment with OE-MSCs and OE-exo protected vascular endothelial integrity, reduced inflammatory cell proliferation, and significantly attenuated intimal hyperplasia of vein graft.

Conclusion

LncRNA MIR155HG could promote the survival and activity of MSCs, and reduce the apoptosis of HUVECs using exosome delivery. Exploiting MSCs and exosomes modified with MIR155HG could attenuate vein graft intimal hyperplasia more effectively and maximize the surgical effect.

Extracellular vesicles produced by human-induced pluripotent stem cell-derived endothelial cells can prevent arterial stenosis in mice via autophagy regulation

Intravascular transplantation of human-induced pluripotent stem cells (hiPSCs) demonstrated a significant therapeutic effect in the treatment of restenosis by the paracrine function of extracellular vesicles (EVs). However, the risk of tumorigenicity and poor cell survival limits its clinical applications. In this study, we for the first time applied a highly efficient and robust three-dimensional (3D) protocol for hiPSC differentiation into endothelial cells (ECs) with subsequent isolation of EVs from the derived hiPSC-EC (ECs differentiated from hiPSCs), and validated their therapeutic effect in intimal hyperplasia (IH) models. We found that intravenously (iv) injected EVs could accumulate on the carotid artery endothelium and significantly alleviate the intimal thickening induced by the carotid artery ligation. To elucidate the mechanism of this endothelial protection, we performed miRNA expression profiling and found out that among the most conserved endothelial miRNAs, miR-126 was the most abundant in hiPSC-EC-produced EVs (hiPSC-EC-EV). MiR-126 depletion from hiPSC-EC-EV can hinder its protective effect on human umbilical vein endothelial cells (HUVECs) in an inflammatory process. A variety of functional in vitro studies revealed that miR-126 was able to prevent endothelial apoptosis after inflammatory stimulation, as well as promote EC migration and tube formation through autophagy upregulation. The latter was supported by in vivo studies demonstrating that treatment with hiPSC-EC-EV can upregulate autophagy in mouse carotid artery ECs, thereby preventing IH and modulating vascular homeostasis via remodeling of the vascular intima. Our findings suggest a regulatory mechanism for the therapeutic effect on arterial restenosis by autophagy regulation, and provide a potential strategy for clinical treatment of the disease.

Intra-arterial injection of mesenchymal stem cells to accelerate neointima formation after endovascular stenting in a rabbit model

OBJECTIVE

Delayed neointima formation over a neurovascular stent is associated with thrombotic complications that can lead to stroke. The purpose of this study was to evaluate whether an intra-arterial injection of mesenchymal stem cells (MSCs) after stent placement leads to improved neointima and reduced thrombus formation over the device.

METHODS

Solitaire stents were placed into the aortas of rabbits that were divided into MSC and control groups. The MSC group received an intra-arterial injection of MSCs through the same microcatheter used for stent deployment. Optical coherence tomography (OCT) was used to evaluate and compare neointima and thrombus formation in a blinded fashion. Explanted specimens were also imaged with scanning electron microscopy (SEM) and evaluated by observers blinded to group allocation using an endothelialization scoring system.

RESULTS

The 3-day MSC group was similar to the 7-day controls in terms of stent strut coverage ratio and maximum neointimal thickness, but these values were significantly higher than the 3-day control group based on a hierarchical mixed-effects linear regression analysis. SEM revealed a significantly higher endothelialization score for the MSC group compared with controls at the same time point. There was no difference in thrombus formation between any of the groups.

CONCLUSIONS

The intra-arterial injection of MSCs after endovascular stenting accelerated early neointima formation but had no effect on thrombus formation in this study. Larger studies are required to verify these findings and determine the durability and mechanism of this effect.

Dendritic epidermal T cells secreting exosomes promote the proliferation of epidermal stem cells to enhance wound re-epithelialization

Background

Efficient re-epithelialization is important for successful skin wound healing. The proportion of epidermal stem cells (EpSCs) and dendritic epidermal T cells (DETCs) determines the extent of wound re-epithelialization, especially in large areas of skin tissue loss. However, it remains unknown whether and how DETCs regulate the status of EpSCs to impact wound re-epithelialization.

Methods

To investigate how DETCs regulate EpSCs in skin re-epithelialization, we utilized normal or full-thickness skin deficient wide type (WT) mice and Tcrσ knockout (Tcrσ^−/−) mice with DETCs or DETCs-derived exosomes (Exos) treatment. Flow cytometry analysis (FCAS), BrdU labelled experiments, immunofluorescence and immunohistochemical assays were performed to detect the proportion of EpSCs in the epidermis. Wound closure rate and re-epithelialization were assayed by a macroscopical view and hematoxylin–eosin (H&E) staining. EpSCs in vitro were co-cultured with DETCs in a transwell-dependent or -independent manner, or supplement with GW4869 or Exos (5 µg/mL, 15 µg/mL and 45 µg/mL), and the proliferation of EpSCs was detected by means of FCAS and CFSE.

Results

Our data showed that the proportion of CD49f^briCD71^dim cells, K15⁺ cells and BrdU⁺ cells in the normal epidermis of Tcrδ^−/− mice had no significant difference compared to WT mice. For wounded Tcrδ^−/− mice, DETCs treatment increase the proportion of CD49f^briCD71^dim cells, K15⁺ cells and BrdU⁺ cells in the epidermis around the wound in comparison to PBS treatment. DETCs significantly increased the number of CD49f^briCD7^dim cells and K15⁺ cells through transwell-dependent or -independent manners relative to control group. Furthermore, Exos stimuli remarkedly promote the proliferation of EpSCs compared to control group, while the increasement was suppressed when DETCs were interfered with GW4869. Gross observation and H&E staining showed that Exos significantly accelerated wound closure and increased re-epithelialization length in Tcrδ^−/− mice when compared to control mice. Additionally, we found in vivo that Exos observably facilitated the proliferation of CD49f^briCD7^dim cells and K15⁺ cells.

Conclusions

We revealed that DETCs enhanced the proliferation of EpSCs in the epidermis around the wounds to accelerate re-epithelialization in which Exos played important roles in the remote regulation of EpSCs proliferation. Together, these findings suggest a mechanistic link among DETC-derived exosomes, the proliferation of EpSCs, and wound re-epithelialization in the skin.

Therapeutic effect and molecular mechanism of Salvia Miltiorrhiza on rats with acute brain injury after carbon monoxide poisoning based on the strategy of internet pharmacology

The pathogenesis of brain injury caused by carbon monoxide poisoning (COP) is very complex, and there is no exact and reliable treatment in clinic. In the present study, we screened the therapeutic target and related signal pathway of Salvia Miltiorrhiza for acute COP brain injury, and clarified the pharmacological mechanism of multicomponent, multitarget, and multisignal pathway in Salvia Miltiorrhiza by network pharmacology. To further verify the therapeutic effect of Salvia Miltiorrhiza on acute brain injury based on the results of network analysis, a total of 216 male healthy Sprague Dawley rats were collected in the present study and randomly assigned to a normal control group, a COP group and a Tanshinone IIA sulfonate treatment group (72 rats in each group). The rat model of acute severe COP was established by the secondary inhalation in a hyperbaric oxygen chamber. We found that Salvia Miltiorrhiza had multiple active components, and played a role in treating acute brain injury induced by COP through multiple targets and multiple pathways, among them, MAPK/ERK1/2 signaling pathway was one of the most important. COP can start apoptosis process, activate the MAPK/ERK1/2 signaling pathway, and promote the expression of VEGF-A protein and the formation of brain edema. Tanshinone IIA can effectively inhibit apoptosis, up-regulate the expressions of VEGF-A, P-MEK1/2 and P-ERK1/2 proteins, thereby protect endothelial cells, promote angiogenesis and microcirculation, and finally alleviate brain edema.

Human umbilical cord mesenchymal stem cell-derived exosomal microRNA-148a-3p inhibits neointimal hyperplasia by targeting Serpine1

BACKGROUND

Restenosis is inevitable when patients undergo percutaneous transluminal angioplasty due to neointimal hyperplasia (NIH). Human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-Exos) have been studied in the field of cardiovascular diseases. However, the effects and mechanisms of hucMSC-Exos on NIH are unclear. We aimed to investigate whether MSC-Exos regulate vascular smooth muscle cell (VSMC) functions to inhibit NIH and explore the underlying mechanisms.

METHODS

HucMSCs and mouse VSMCs were isolated and characterized by flow cytometry and immunofluorescence. HucMSC-Exos were identified by transmission electron microscopy, nanoparticle tracking analysis and western blots. Exosomes (Exos) were intravenously injected into mice with left common carotid artery ligation, and their effects on NIH were assessed by haematoxylin and eosin (H&E) and immunohistochemistry staining. The effects of hucMSC-Exos on VSMCs were evaluated by Cell Counting Kit-8, scratch wound, Transwell and Western blot assays. MicroRNA sequencing data in the Gene Expression Omnibus and mRNA sequencing results were used to identify potential molecules in hucMSC-Exos and target genes in VSMCs, respectively. We tested the regulatory effect of microRNAs in Exos and target genes in VSMCs using overexpression and knockdown experiments.

RESULTS

Primary hucMSCs, VSMCs and hucMSC-Exos were isolated and characterized. Administration of hucMSC-Exos suppressed NIH after artery ligation. H&E and immunohistochemistry results showed that hucMSC-Exos decreased the intima and media area and intima/media ratio, increased the contractile phenotype protein SM22a in the media layer and downregulated Serpine1 expression in the carotid artery. Exos were ingested by VSMCs, which inhibited migration and upregulated SM22a expression by suppressing Serpine1 expression in vitro. MiR-148a-3p was enriched in hucMSC-Exos and repressed Serpine1 by targeting its 3' untranslated region. Moreover, exosomal miR-148a-3p suppressed VSMC phenotypic switching and migration by targeting Serpine1.

CONCLUSIONS

We found that hucMSC-Exos inhibited NIH in a mouse carotid artery ligation model and that the inhibitory effects on VSMC phenotypic switching and migration were mediated by delivery of miR-148a-3p to VSMCs to target Serpine1.

Exosomes from mesenchymal stem cells expressing microribonucleic acid-125b inhibit the progression of diabetic nephropathy via the tumour necrosis factor receptor-associated factor 6/Akt axis

Diabetic nephropathy (DN) seriously threatens the health of patients with diabetes. Moreover, it has been reported that mesenchymal stem cell (MSC)-derived exosomal miRNAs can modulate the progression of multiple diseases, including DN. It has been suggested that miR-125b is involved in DN. However, the biological functions of exosomal miRNAs, especially miR-125b, in DN are still unclear. To establish a DN model in vitro, we used a model of human embryonic kidney epithelial cells (HKCs) injury induced by high glucose (HG). Then, miR-125b was delivered to the model cells in vitro via MSC-derived exosomes (MSC-Exos), and the effect of exosomal miR-125b on HKCs apoptosis was evaluated by flow cytometry. qRT-PCR or western blotting was performed to measure miR-125b or tumour necrosis factor receptor-associated factor 6 (TRAF6) expression in HKC. The effect of MSC-Exos on HKCs apoptosis after miR-125b knockdown was determined by flow cytometry. Moreover, dual-luciferase reporter assays were used to determine the targeting relationship between miR-125b and TRAF6 in HKCs. Our data revealed that MSC-Exos increased HG-induced autophagy in HKCs and reversed HKCs apoptosis. Moreover, our study found that miR-125b was enriched in MSC-Exos and directly targeted TRAF6 in HKCs. In addition, exosomally transferred miR-125b inhibited the apoptosis of HG-treated HKCs by mediating Akt signalling. In summary, MSC-derived exosomal miR-125b induced autophagy and inhibited apoptosis in HG-treated HKCs via the downregulation of TRAF6. Therefore, our study provided a new idea for DN treatment.

Exosomal microRNA-1246 from human umbilical cord mesenchymal stem cells potentiates myocardial angiogenesis in chronic heart failure

microRNAs (miRNAs) are of importance to chronic heart failure (CHF). However, the relevance of the exosomal miRNAs produced during CHF remains unknown. Our purpose here was to examine the relevance of exosomal microRNA-1246 (miR-1246) released from human umbilical cord mesenchymal stem cell (hucMSC) during CHF and the mechanism of action. Cardiac function, myocardial infarction area, apoptosis, and angiogenesis were all evaluated in a CHF rat model following treatment with hucMSC-derived exosomes (hucMSC-Exos). H9C2 and human umbilical vascular endothelial cells (HUVECs) were subjected to oxygen and glucose deprivation and exosome treatment to quantify the cell proliferation and apoptosis in H9C2 cells and the tube formation capacity of the HUVECs. A dual-luciferase activity reporter assay was conducted to validate the interaction between miR-1246 and serine protease 23 (PRSS23). HucMSCs treatment led to a reduction in H9C2 apoptosis and an increase in HUVEC angiogenesis, which were mitigated when hucMSCs were treated with a miR-1246 inhibitor. We also confirmed that PRSS23 is a putative target of miR-1246 and that miR-1246 attenuated hypoxia-induced myocardial tissue damage by targeting PRSS23 and inhibiting the activation of the Snail/alpha-smooth muscle actin signaling. Our findings suggest that exosomal miR-1246 from hucMSCs protects the heart from failure by targeting PRSS23.

Aralia armata (Wall.) Seem Improves Intimal Hyperplasia after Vascular Injury by Downregulating the Wnt3α/Dvl-1/β-Catenin Pathway

The aim of the study is to examine the mechanism of Aralia armata (Wall.) Seem (AAS) in improving intimal hyperplasia after vascular injury in rats. Rats with femoral artery injury were randomly divided into three groups: the model group, AAS low-dose group (40 mg/kg), and AAS high-dose group (80 mg/kg). The sham operation group was used as a control group. HE staining was used to observe the changes in femoral artery vessels. Immunohistochemistry was adopted to detect α-SMA, PCNA, GSK-3β, and β-catenin proteins in femoral artery tissue. The CCK-8 test and wound healing assay were employed to analyze the effect of AAS on proliferation and migration of vascular smooth muscle cells (VSMCs) cultured in vitro. Western blotting (WB) and polymerase chain reaction (PCR) assays were used to evaluate the molecular mechanism. AAS reduced the stenosis of blood vessels and the protein expressions of α-SMA, PCNA, GSK-3β, and β-catenin compared to the model group. In addition, AAS (0-15 μg/mL) effectively inhibited the proliferation and migration of VSMCs. Moreover, the results of WB and PCR showed that AAS could inhibit the activation of β-catenin induced by 15% FBS and significantly decrease the expression levels of Wnt3α, Dvl-1, GSK-3β, β-catenin, and cyclin D1 in the upstream and downstream of the pathway. AAS could effectively inhibit the proliferation and migration of neointima after vascular injury in rats by regulating the Wnt/β-catenin signaling pathway.

Bone marrow mesenchymal stem cells-secreted exosomal microRNA-205-5p exerts inhibitory effect on the progression of liver cancer through regulating CDKL3

OBJECTIVE

Bone marrow mesenchymal stem cells-derived exosomes (BMSCs-exo) carrying microRNA (miR) cargo have been emerged as a promising therapy for human cancers. Therein, we pivoted on the integral function of BMSCs-exo and miR-205-5p in liver cancer through mediation of cyclin-dependent kinase-like 3 (CDKL3).

METHODS

Patients with liver cancer were enrolled to collect the clinical tissue and determine miR-205-5p and CDKL3 expression. miR-205-5p expression in BMSCs was altered by transfection, and BMSCs-exo were extracted and co-cultured with LM3 cells. Meanwhile, LM3 cells were independently transfected with CDKL3 low or high expression vector. Since then, cell growth in vitro was observed, and the effect of exosomal miR-205-5p on tumor growth in vivo was further investigated.

RESULTS

miR-205-5p expression was low while CDKL3 was high in liver cancer. BMSCs-exo blocked cellular growth of liver cancer in vitro and in vivo. Overexpressing exosomal miR-205-5p decelerated the biological development of liver cancer cells while suppressing exosomal miR-205-5p had the contrary function in vitro and in vivo. Loss of CDKL3 impaired the malignant activities of liver cancer cells, and could even impair the pro-tumor effects of down-regulated exosomal miR-205-5p.

CONCLUSION

It is clearly concluded that BMSCs-secreted exosomal miR-205-5p exerts inhibitory effect on the progression of liver cancer through regulating CDKL3.

Factors Affecting the Re-Endothelialization of Endothelial Progenitor Cell

The vascular endothelium, which plays an essential role in maintaining the normal shape and function of blood vessels, is a natural barrier between the circulating blood and the vascular wall tissue. The endothelial damage can cause vascular lesions, such as atherosclerosis and restenosis. After the vascular intima injury, the body starts the endothelial repair (re-endothelialization) to inhibit the neointimal hyperplasia. Endothelial progenitor cell is the precursor of endothelial cells and plays an important role in the vascular re-endothelialization. However, re-endothelialization is inevitably affected in vivo and in vitro by factors, which can be divided into two types, namely, promotion and inhibition, and act on different links of the vascular re-endothelialization. This article reviews these factors and related mechanisms.

Exosomes and cancer: from molecular mechanisms to clinical applications

Exosomes are extracellular nanovesicles secreted from almost all types of normal and cancer cells. Collective evidence suggests that exosomes participate in cell-cell communication via transmitting their cargo, including nucleic acids, proteins, and metabolites to recipient cells. Tumor-derived exosomes (TEXs) play prominent roles in the regulation of molecular pathways in malignancies. Internalization of exosomes by tumor cells affects cellular pathways and several cancer hallmarks, including reprogramming of stromal cells, modulating immune responses, reconstructing extracellular matrix architecture, or even endowing tumor cells with drug features resistance. The unique biogenesis pathways of exosomes, their composition, low immunogenicity, and nontoxicity, together with their ability to target tumor cells, bring them up as an attractive vesicles for cancer therapy. Thus, understanding the molecular mechanisms of exosomes' participation in tumorigenesis will be critical for the next generation of cancer therapeutics. This review aims to summarize the exosomes' roles in different mechanisms underlying cancer progression for the rational design of tailored strategies against this illness. The present study also highlights the new findings on using these smart vesicles as therapeutic targets and potential biomarkers. Recent advances in exosome biology will open up new, more effective, less invasive, and more individualized clinical applications for treating cancer patients.

Emerging biogenesis technologies of extracellular vesicles for tissue regenerative therapeutics

Extracellular vesicles (EVs), including exosomes, carry the genetic packages of RNA, DNA, and proteins and are heavily involved in cell-cell communications and intracellular signalings. Therefore, EVs are spotlighted as therapeutic mediators for the treatment of injured and dysfunctional tissues as well as biomarkers for the detection of disease status and progress. Several key issues in EVs, including payload content and bioactivity, targeting and bio-imaging ability, and mass-production, need to be improved to enable effective therapeutics and clinical translation. For this, significant efforts have been made recently, including genetic modification, biomolecular and chemical treatment, application of physical/mechanical cues, and 3D cultures. Here we communicate those recent technological advances made mainly in the biogenesis process of EVs or at post-collection stages, which ultimately aimed to improve the therapeutic efficacy in tissue healing and disease curing and the possibility of clinical translation. This communication will help tissue engineers and biomaterial scientists design and produce EVs optimally for tissue regenerative therapeutics.

Recent Advances in Extracellular Vesicles as Drug Delivery Systems and Their Potential in Precision Medicine

Extracellular vesicles (EVs) are membrane-bilayered nanoparticles released by most cell types. Recently, an enormous number of studies have been published on the potential of EVs as carriers of therapeutic agents. In contrast to systems such as liposomes, EVs exhibit less immunogenicity and higher engineering potential. Here, we review the most relevant publications addressing the potential and use of EVs as a drug delivery system (DDS). The information is divided based on the key steps for designing an EV-mediated delivery strategy. We discuss possible sources and isolation methods of EVs. We address the administration routes that have been tested in vivo and the tissue distribution observed. We describe the current knowledge on EV clearance, a significant challenge towards enhancing bioavailability. Also, EV-engineering approaches are described as alternatives to improve tissue and cell-specificity. Finally, a summary of the ongoing clinical trials is performed. Although the application of EVs in the clinical practice is still at an early stage, a high number of studies in animals support their potential as DDS. Thus, better treatment options could be designed to precisely increase target specificity and therapeutic efficacy while reducing off-target effects and toxicity according to the individual requirements of each patient.