Pre-treatments enhance the therapeutic effects of mesenchymal stem cells in liver diseases

Extracellular vesicles derived from "serum and glucose" deprived HUCMSCs promoted skin wound healing through enhanced angiogenesis

Extracellular vesicles (EVs) produced from MSCs were currently considered as a novel therapeutic agent for skin tissue regeneration and repair. Preconditioning stem cells may activate more molecular pathways and release more bioactive agents. In this study, we obtained EVs from normal (N-EVs) and serum- and glucose-deprived (SGD-EVs) human umbilical cord mesenchymal stem cells (HUCMSCs), and showed that SGD-EVs promoted the migration, proliferation, and tube formation of HUVECs in vitro. In vivo experiments utilizing a rat model show that both N-EVs and SGD-EVs boosted angiogenesis of skin defects and accelerated skin wound healing, while treating wounds with SGD-EVs led to faster skin healing and enhanced angiogenesis. miRNA sequencing showed that miR-29a-3p was abundant in SGD-EVs, and overexpressing miR-29a-3p enhanced the angiogenic ability of HUVECs, while inhibiting miR-29a-3p presented the opposite effect. Further studies demonstrated that miR-29a-3p directly targeted CTNNBIP1, which mediated angiogenesis of HUCMSCs-derived EVs through inhibiting CTNNBIP1 to activate Wnt/β-catenin signaling pathway. Taken together, these findings suggested that SGD-EVs promote angiogenesis via transferring miR-29a-3p, and activation of Wnt/β-catenin signaling pathway played a crucial role in SGD-EVs-induced VEGFA production during wound angiogenesis. Our results offered a new avenue for modifying EVs to enhance tissue angiogenesis and augment its role in skin repair.

Progress of mesenchymal stem cells (MSCs) & MSC-Exosomes combined with drugs intervention in liver fibrosis

Liver fibrosis is an intrahepatic chronic damage repair response caused by various reasons such as alcoholic liver, fatty liver, viral hepatitis, autoimmune diseases, etc., and is closely related to the progression of liver disease. Currently, the mechanisms of liver fibrosis and its treatment are hot research topics in the field of liver disease remedy. Mesenchymal stem cells (MSCs) are a class of adult stem cells with self-renewal and multidirectional differentiation potential, which can ameliorate fibrosis through hepatic-directed differentiation, paracrine effects, and immunomodulation. However, the low inner-liver colonization rate, low survival rate, and short duration of intervention after stem cell transplantation have limited their wide clinical application. With the intensive research on liver fibrosis worldwide, it has been found that MSCs and MSCs-derived exosomes combined with drugs have shown better intervention efficiency than utilization of MSCs alone in many animal models of liver fibrosis. In this paper, we review the interventional effects and mechanisms of mesenchymal stem cells and their exosomes combined with drugs to alleviate hepatic fibrosis in vivo in animal models in recent years, which will provide new ideas to improve the efficacy of mesenchymal stem cells and their exosomes in treating hepatic fibrosis in the clinic.

Challenges of mesenchymal stem cells in the clinical treatment of COVID-19

The 2019 coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has brought an enormous public health burden to the global society. The duration of the epidemic, the number of infected people, and the widespread of the epidemic are extremely rare in modern society. In the initial stage of infection, people generally show fever, cough, and dyspnea, which can lead to pneumonia, acute respiratory syndrome, kidney failure, and even death in severe cases. The strong infectivity and pathogenicity of SARS-CoV-2 make it more urgent to find an effective treatment. Mesenchymal stem cells (MSCs) are a kind of pluripotent stem cells with the potential for self-renewal and multi-directional differentiation. They are widely used in clinical experiments because of their low immunogenicity and immunomodulatory function. Mesenchymal stem cell-derived exosomes (MSC-Exo) can play a physiological role similar to that of stem cells. Since the COVID-19 pandemic, a series of clinical trials based on MSC therapy have been carried out. The results show that MSCs are safe and can significantly improve patients' respiratory function and prognosis of COVID-19. Here, the effects of MSCs and MSC-Exo in the treatment of COVID-19 are reviewed, and the clinical challenges that may be faced in the future are clarified.

Bioengineered MSCGFPCxcr2-Mmp13 Transplantation Alleviates Hepatic Fibrosis by Regulating Mammalian Target of Rapamycin Signaling

Aims: Hepatic fibrosis is the pathological change during chronic liver diseases (CLD) that turns into cirrhosis if not reversed timely. Allogenic mesenchymal stem cell (MSC) therapy is an alternative to liver transplantation for CLD. However, poor engraftment of the transplanted MSCs limits their therapeutic efficacy. MSCs express chemokine receptors that regulate their physiology. We observed several-fold increased expressions of Cxcl3 and decreased expression of Mmp13 in the fibrotic liver. Therefore, we bioengineered MSCs with stable overexpression of Cxcr2 (CXCL3-cognate receptor) and Mmp13, collagenase (MSCGFPCxcr2-Mmp13). Results: The CXCL3/CXCR2 axis significantly increased migration through the activation of AKT/ERK/mTOR signaling. These bioengineered MSCs transdifferentiated into hepatocyte-like cells (MSCGFPCxcr2-Mmp13-HLCs) that endured the drug-/hepatotoxicant-induced toxicity by significantly increasing the antioxidants-Nrf2 and Sod2, while decreasing the apoptosis-Cyt C, Casp3, Casp9, and drug-metabolizing enzyme-Cyp1A1, Cyp1A2, Cyp2E1 markers. Therapeutic transplantation of MSCGFPCxcr2-Mmp13 abrogated AAP-/CCl4-induced hepatic fibrosis in mice by CXCR2-mediated targeted engraftment and MMP-13-mediated reduction in collagen. Mechanistically, induction of CXCL3/CXCR2 axis-activated mTOR-p70S6K signaling led to increased targeted engraftment and modulation of the oxidative stress by increasing the expression and activity of nuclear Nrf2 and SOD2 expression in the regenerated hepatic tissues. A marked change in the fate of transplanted MSCGFPCxcr2-Mmp13 toward hepatocyte lineage demonstrated by co-immunostaining of GFP/HNF4α along with reduced COL1α1 facilitated the regeneration of the fibrotic liver. Innovation and Conclusions: Our study suggests the therapeutic role of allogenic Cxcr2/Mmp13-bioengineered MSC transplantation decreases the hepatic oxidative stress as an effective translational therapy for hepatic fibrosis mitigation-mediated liver regeneration.

Stem cell therapy for hepatocellular carcinoma and end-stage liver disease

Hepatocellular carcinoma (HCC) is a major health problem worldwide, especially for patients who are suffering from end-stage liver disease (ESLD). The ESLD is considered a great challenge for clinicians due to the limited chance for liver transplantation, which is the only curative treatment for those patients. Stem cell-based therapy as a part of regenerative medicine represents a promising application for ESLD patients. Many clinical trials were performed to assess the utility of bone marrow-derived stem cells as a potential therapy for patients with liver diseases. The aim of the present study is to present and review the various types of stem cell-based therapy, including the mesenchymal stem cells (MSCs), BM-derived mononuclear cells (BM-MNCs), CD34 + hematopoietic stem cells (HSCs), induced pluripotent stem cells (iPSCs), and cancer stem cells.Though this type of therapy achieved promising results for the treatment of ESLD, however still there is a confounding data regarding its clinical application. A large body of evidence is highly required to evaluate the stem cell-based therapy after long-term follow-up, with respect to the incidence of toxicity, immunogenicity, and tumorigenesis that developed in many patients.

Application of mesenchymal stem cells in regenerative medicine: A new approach in modern medical science

Mesenchymal Stem Cells (MSCs) are non-hematopoietic and multipotent stem cells, which have been considered in regenerative medicine. These cells are easily separated from different sources, such as bone marrow (BM), umbilical cord (UC), adipose tissue (AT), and etc. MSCs have the differentiation capability into chondrocytes, osteocytes, and adipocytes; This differentiation potential along with the paracrine properties have made them a key choice for tissue repair. MSCs also have various advantages over other stem cells, which is why they have been extensively studied in recent years. The effectiveness of MSCs-based therapies depend on several factors, including differentiation status at the time of use, concentration per injection, delivery method, the used vehicle, and the nature and extent of the damage. Although, MSCs have emerged promising sources for regenerative medicine, there are potential risks regarding their safety in their clinical use, including tumorigenesis, lack of availability, aging, and sensitivity to toxic environments. In this study, we aimed to discuss how MSCs may be useful in treating defects and diseases. To this aim, we will review recent advances of MSCs action mechanisms in regenerative medicine, as well as the most recent clinical trials. We will also have a brief overview of MSCs resources, differences between their sources, culture conditions, extraction methods, and clinical application of MSCs in various fields of regenerative medicine.

Mesenchymal stem cell-regulated miRNA-mRNA landscape in acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a major challenge in the field of hepatology. While mesenchymal stem cell (MSC) therapy can improve the prognosis of patients with ACLF, the molecular mechanisms through which MSCs attenuate ACLF remain poorly understood. We performed global miRNA and mRNA expression profiling via next-generation sequencing of liver tissues from MSC-treated ACLF mice to identify important signaling pathways and major factors implicated in ACLF alleviation by MSCs.

METHODS

Carbon tetrachloride-induced ACLF mice were treated with saline or mouse bone marrow-derived MSCs. Mouse livers were subjected to miRNA and mRNA sequencing. Related signal transduction pathways were obtained through Gene Set Enrichment Analysis. Functional enrichment, protein-protein interaction, and immune infiltration analyses were performed for the differentially expressed miRNA target genes (DETs). Hub miRNA and mRNA associated with liver injury were analyzed using LASSO regression. The expression levels of hub genes were subjected to Pearson's correlation analysis and verified using RT-qPCR. The biological functions of hub genes were verified in vitro.

RESULTS

The tricarboxylic acid cycle and peroxisome proliferator-activated receptor pathways were activated in the MSC-treated groups. The proportions of liver-infiltrating NK resting cells, M2 macrophages, follicular helper T cells, and other immune cells were altered after MSC treatment. The expression levels of six miRNAs and 10 transcripts correlated with the degree of liver injury. miR-27a-5p was downregulated in the mouse liver after MSC treatment, while its target gene E2f2 was upregulated. miR-27a-5p inhibited E2F2 expression, suppressed G1/S phase transition and proliferation of hepatocytes, in addition to promoting their apoptosis.

CONCLUSIONS

This is the first comprehensive analysis of miRNA and mRNA expression in the liver tissue of ACLF mice after MSC treatment. The results revealed global changes in hepatic pathways and immune subpopulations. The miR-27a-5p/E2F2 axis emerged as a central regulator of the MSC-induced attenuation of ACLF. The current findings improve our understanding of the molecular mechanisms through which MSCs alleviate ACLF.

Advances in stem cell therapy for peritoneal fibrosis: from mechanisms to therapeutics

Peritoneal fibrosis (PF) is a pathophysiological condition caused by a variety of pathogenic factors. The most important features of PF are mesothelial-mesenchymal transition and accumulation of activated (myo-)fibroblasts, which hinder effective treatment; thus, it is critical to identify other practical approaches. Recently, stem cell (SC) therapy has been indicated to be a potential strategy for this disease. Increasing evidence suggests that many kinds of SCs alleviate PF mainly by differentiating into mesothelial cells; secreting cytokines and extracellular vesicles; or modulating immune cells, particularly macrophages. However, there are relatively few articles summarizing research in this direction. In this review, we summarize the risk factors for PF and discuss the therapeutic roles of SCs from different sources. In addition, we outline effective approaches and potential mechanisms of SC therapy for PF. We hope that our review of articles in this area will provide further inspiration for research on the use of SCs in PF treatment.

Comparative Histological Study of Therapeutic Effect of Mesenchymal Stem Cells versus Mesenchymal Stem Cells Co-Cultured with Liver Tissue on Carbon Tetrachloride-Induced Hepatotoxicity in Adult Male Albino Rats

Context

Liver diseases are major causes of morbidity and mortality. Mesenchymal stem cells (MSCs) have immunomodulatory, anti-inflammatory, and antifibrotic effects, so they can be used in the treatment of liver diseases. MSCs co-cultured with diseased liver tissue improve the homing capacity, survival rate, and paracrine effects of the MSCs, as well as the ability to enhance liver function.

Aims

This work aimed to study the therapeutic effect of MSCs versus MSCs co-cultured with liver tissue on carbon tetrachloride (CCl4)-induced hepatotoxicity in adult male albino rats.

Settings and Design

Twenty adult male albino rats were divided into four equal groups; Group I (control group), Group II received CCl4 intraperitoneally (i.p.), Group III received CCl4 i.p. and then injected with MSCs intravenously (i.v.), and Group IV received CCl4 i.p. and then injected with co-cultured MSCs i.v.

Materials and Methods

Finally, liver specimens were processed for light microscopy (LM) and electron microscopy (EM). Statistical analysis was carried out to assess histological scoring, area percentage of collagen fibers, number of glial fibrillary acidic protein-positive cells, and biochemical analysis of alanine aminotransferase and aspartate aminotransferase.

Statistical Analysis Used

Statistical analysis of (histological scoring, area % of collagen fibers, and biochemical analysis) was done by using one-way analysis of variance (ANOVA) test using graphpad software (SanDiego, CA, USA). The means ± standard deviations were used for statistical analysis.

Results

LM of Group II revealed loss of hepatic architecture and diffuse fibrosis with dilated congested blood vessels, bile ductular proliferation, and cellular infiltrations. Vacuolated cytoplasm with or without pyknotic nuclei was observed in addition to micro- and macro-steatosis. EM demonstrated disfigured hepatocytes with abnormal organelles surrounding atypical nucleus. Group III showed restoration of the normal liver architecture with greater extent in Group IV. Statistical analysis confirmed the microscopic findings.

Conclusions

Co-cultured MSCs with diseased liver tissue augmented the therapeutic effects of MSCs in treating hepatotoxicity induced by CCl4 in adult male albino rats.

Multiple Dimensions of using Mesenchymal Stem Cells for Treating Liver Diseases: From Bench to Beside

Liver diseases impose a huge burden worldwide. Although hepatocyte transplantation has long been considered as a potential strategy for treating liver diseases, its clinical implementation has created some obvious limitations. As an alternative strategy, cell therapy, particularly mesenchymal stem cell (MSC) transplantation, is widely used in treating different liver diseases, including acute liver disease, acute-on-chronic liver failure, hepatitis B/C virus, autoimmune hepatitis, nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, alcoholic liver disease, liver fibrosis, liver cirrhosis, and hepatocellular carcinoma. Here, we summarize the status of MSC transplantation in treating liver diseases, focusing on the therapeutic mechanisms, including differentiation into hepatocyte-like cells, immunomodulating function with a variety of immune cells, paracrine effects via the secretion of various cytokines and extracellular vesicles, and facilitation of homing and engraftment. Some improved perspectives and current challenges are also addressed. In summary, MSCs have great potential in the treatment of liver diseases based on their multi-faceted characteristics, and more accurate mechanisms and novel therapeutic strategies stemming from MSCs will facilitate clinical practice.

Enhancing mesenchymal stem cell survival and homing capability to improve cell engraftment efficacy for liver diseases

Although mesenchymal stem cell (MSC) transplantation provides an alternative strategy for end-stage liver disease (ESLD), further widespread application of MSC therapy is limited owing to low cell engraftment efficiency. Improving cell engraftment efficiency plays a critical role in enhancing MSC therapy for liver diseases. In this review, we summarize the current status and challenges of MSC transplantation for ESLD. We also outline the complicated cell-homing process and highlight how low cell engraftment efficiency is closely related to huge differences in extracellular conditions involved in MSC homing journeys ranging from constant, controlled conditions in vitro to variable and challenging conditions in vivo. Improving cell survival and homing capabilities enhances MSC engraftment efficacy. Therefore, we summarize the current strategies, including hypoxic priming, drug pretreatment, gene modification, and cytokine pretreatment, as well as splenectomy and local irradiation, used to improve MSC survival and homing capability, and enhance cell engraftment and therapeutic efficiency of MSC therapy. We hope that this review will provide new insights into enhancing the efficiency of MSC engraftment in liver diseases.

The high level of IL-1β in the serum of ACLF patients induces increased IL-8 expression in hUC-MSCs and reduces the efficacy of hUC-MSCs in liver failure

BACKGROUND

Stem cells play a therapeutic role mainly through immunoregulation. However, the immunomodulatory function of stem cells may be affected by inflammation-related factors in patients' serum. Therefore, this study aims to investigate the possible mechanism by which acute-on-chronic liver failure (ACLF) patient serum influences the efficacy of hUC-MSCs.

METHODS

The serum of surviving and dead ACLF patients was collected to culture hUC-MSCs in vitro, and the hUC-MSCs cultured in the serum of ACLF patients were used to treat acute liver failure (ALF) rats. The therapeutic effect on the rats was evaluated by a survival curve, the transaminase level and liver histopathology. The expression of cytokines in hUC-MSCs was detected by Q-PCR and ELISA.

RESULTS

Serum pretreatment reduced the therapeutic effect of hUC-MSCs on ALF, especially pretreatment in the serum from dead ACLF patients. After hUC-MSCs were cultured in the serum of surviving or dead ACLF patients, the most differentially expressed factor was IL-8. Interfering with the expression of IL-8 in hUC-MSCs can improve the therapeutic effect of hUC-MSCs on ALF. The high level of IL-1β in the serum of dead ACLF patients causes the increased expression of IL-8 in hUC-MSCs through the activation of the NF-κB signaling pathway. Meanwhile, we found that the neutralizing IL-1β in serum from dead ACLF patients can improve the therapeutic effect of hUC-MSCs on ALF.

CONCLUSION

The high level of IL-1β in ACLF serum can promote the expression of IL-8 in hUC-MSCs through the NF-κB signaling pathway, thus reducing the effect of hUC-MSCs on ALF.

Magnetic Nanostructures and Stem Cells for Regenerative Medicine, Application in Liver Diseases

The term "liver disease" refers to any hepatic condition that leads to tissue damage or altered hepatic function and can be induced by virus infections, autoimmunity, inherited genetic mutations, high consumption of alcohol or drugs, fat accumulation, and cancer. Some types of liver diseases are becoming more frequent worldwide. This can be related to increasing rates of obesity in developed countries, diet changes, higher alcohol intake, and even the coronavirus disease 2019 (COVID-19) pandemic was associated with increased liver disease-related deaths. Although the liver can regenerate, in cases of chronic damage or extensive fibrosis, the recovery of tissue mass is impossible, and a liver transplant is indicated. Because of reduced organ availability, it is necessary to search for alternative bioengineered solutions aiming for a cure or increased life expectancy while a transplant is not possible. Therefore, several groups were studying the possibility of stem cells transplantation as a therapeutic alternative since it is a promising strategy in regenerative medicine for treating various diseases. At the same time, nanotechnological advances can contribute to specifically targeting transplanted cells to injured sites using magnetic nanoparticles. In this review, we summarize multiple magnetic nanostructure-based strategies that are promising for treating liver diseases.

TNF-α/IL-1β-licensed hADSCs alleviate cholestatic liver injury and fibrosis in mice via COX-2/PGE2 pathway

BACKGROUND

Adipose tissue-derived stem cell (ADSC) transplantation has been shown to be effective for the management of severe liver disorders. Preactivation of ADSCs enhanced their therapeutic efficacy. However, these effects have not yet been examined in relation to cholestatic liver injury.

METHODS

In the present study, a cholestatic liver injury model was established by bile duct ligation (BDL) in male C57BL/6 mice. Human ADSCs (hADSCs) with or without tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) pretreatment were administrated into the mice via tail vein injections. The efficacy of hADSCs on BDL-induced liver injury was assessed by histological staining, real-time quantitative PCR (RT-qPCR), Western blot, and enzyme-linked immune sorbent assay (ELISA). In vitro, the effects of hADSC conditioned medium on the activation of hepatic stellate cells (HSCs) were investigated. Small interfering RNA (siRNA) was used to knock down cyclooxygenase-2 (COX-2) in hADSCs.

RESULTS

TNF-α/IL-1β preconditioning could downregulate immunogenic gene expression and enhance the engraftment efficiency of hADSCs. Compared to control hADSCs (C-hADSCs), TNF-α/IL-1β-pretreated hADSCs (P-hADSCs) significantly alleviated BDL-induced liver injury, as demonstrated by reduced hepatic cell death, attenuated infiltration of Ly6G + neutrophils, and decreased expression of pro-inflammatory cytokines TNF-α, IL-1β, C-X-C motif chemokine ligand 1 (CXCL1), and C-X-C motif chemokine ligand 2 (CXCL2). Moreover, P-hADSCs significantly delayed the development of BDL-induced liver fibrosis. In vitro, conditioned medium from P-hADSCs significantly inhibited HSC activation compared to that from C-hADSCs. Mechanistically, TNF-α/IL-1β upregulated COX-2 expression and increased prostaglandin E2 (PGE2) secretion. The blockage of COX-2 by siRNA transfection reversed the benefits of P-hADSCs for PGE2 production, HSC activation, and liver fibrosis progression.

CONCLUSION

In conclusion, our results suggest that TNF-α/IL-1β pretreatment enhances the efficacy of hADSCs in mice with cholestatic liver injury, partially through the COX-2/PGE2 pathway.

Menstrual blood-derived endometrial stem cells alleviate neuroinflammation by modulating M1/M2 polarization in cell and rat Parkinson's disease models

BACKGROUND

Neuroinflammation is closely related to the development of Parkinson's disease (PD). Because of the extensive sources, non-invasive and periodical collection method, human menstrual blood-derived endometrial stem cells (MenSCs) have been explored as a promising tool for treatment of PD. This study aimed to investigate if MenSCs could inhibit neuroinflammation in PD rats by regulating M1/M2 polarization and to excavate the underlying mechanisms.

METHODS

MenSCs were co-cultured with 6-OHDA-exposed microglia cell lines. Then the morphology of microglia cells and the level of inflammatory factors were assessed by immunofluorescence and qRT-PCR. After MenSCs were transplanted into the brain of PD rats, animal motor function, the expression of tyrosine hydroxylase, and the level of inflammatory factors in the cerebrospinal fluid (CSF) and serum were detected to evaluate the therapeutic potential of MenSCs. Meanwhile, the expression of M1/M2 phenotype related genes was detected by qRT-PCR. One protein array kit containing 1000 kinds of factors was used to detect the protein components in the conditioned medium of MenSCs. Finally, bioinformatic analysis was performed to analyze the function of factors secreted by MenSCs and the signal pathways involved in.

RESULTS

MenSCs could suppress 6-OHDA-induced microglia cell activation and significantly decrease inflammation in vitro. After transplantation into the brain of PD rats, MenSCs improved animal motor function, which was indicated by the increased movement distance, ambulatory episodes, exercise time on the rotarod, and less contralateral rotation. Additionally, MenSCs reduced the loss of dopaminergic neurons and down-regulated the level of pro-inflammatory factors in the CSF and serum. Moreover, q-PCR and WB results showed the transplantation of MenSCs significantly down-regulated the expression of M1 phenotype cell markers and meanwhile up-regulated the expression of M2 phenotype cell markers in the brain of PD rats. 176 biological processes including inflammatory response, negative regulation of apoptotic process, and microglial cell activation were enriched by GO-BP analysis. 58 signal pathways including PI3K/Akt and MAPK were enriched by KEGG analysis.

CONCLUSIONS

In conclusion, our results provide preliminary evidence for the anti-inflammation capacity of MenSCs by regulating M1/M2 polarization. We firstly demonstrated the biological process of factors secreted by MenSCs and the signal pathways involved in using protein array and bioinformatic analysis.

Curcumin Nanofiber PCL/PLGA/Collagen Enhanced the Therapeutic Efficacy of Mesenchymal Stem Cells against Liver Fibrosis in Animal Model and Prevented its Recurrence

The aim of this study is preconditioning of hBM-MSCs using curcumin modified nanomembrane to optimize therapy of hepatic fibrosis and preventing its recurrence. Methods: The nanomembrane was prepared by electrospinning technique and characterized using conventional method (cur^- nanoscaffold and cur⁺ nanoscaffold). Kinetic release of curcumin was also measured by spectrophotometry. MSCs were isolated from human bone marrow (hBM-MSCs) and cultured on the both nanoscaffolds. We evaluated the in-vivo effect of hBM-MSCs from both nanoscaffold cultures (cur^- nanoscaffold/hMSCs and cur⁺ nanoscaffold/MSCs) on liver fibrosis from its effective and preventive points and we assessed the mechanisms of these effects as in vitro studies as cell proliferation, its effect on hepatogenic differentiation, its effect on paracrine release of hBM-MSCs and in-vivo studying the effect on cell migration, survival, engraftment, fate of transplanted cells, modifying the fibrogenic and inflammatory microenvironments. Results: The results of animal model showed that single injection of preconditioning of hBM-MSCs using curcumin modified nanoscaffold ameliorate the fibrosis and prevent its recurrence until 24 weeks of therapy in contrast to improvement but not ameliorative effect of hBM-MSCs/ curcumin negative nanoscaffold which recurred progressively after 12 weeks of therapy. These effects of curcumin modified nanoscaffold were results from its highly efficacy on cell proliferation, in-vitro and in-vivo hepatogenic differentiation, increasing cell migration, engraftment and survival in the inflammatory microenvironment which was markedly improved by down regulation of inflammatory mediators and upregulation of anti-oxidant factors. Conclusion: hBM-MSCs cultured on the prepared curcumin nanomembrane in this study is promising in regenerative therapy for ameliorating the hepatic fibrosis and to prevent its recurrence.

Exosomes Derived from microRNA-27a-3p Overexpressing Mesenchymal Stem Cells Inhibit the Progression of Liver Cancer through Suppression of Golgi Membrane Protein 1

Hepatocellular carcinoma (HCC) remains a significant health burden to date. Its early diagnosis and treatment are complicated by the lack of early diagnosis markers and multidrug resistance. microRNA regulation of HCC oncogenes are among the new diagnostic and therapeutic strategies being explored, although the mode of delivery of a therapeutic dose of the miRNA remains a challenge. In this study, we explored the use of exosomes from umbilical mesenchymal stem cells transfected with miR-27a-3p to interact with the oncogene GOLM1 in HCC and inhibit HCC progression both in vitro and in vivo. We first determined and compared the expression levels of miR-27a-3p in blood, various cell lines and tissues of HCC and their corresponding normal controls. We then employed bioinformatics analysis to determine the gene target for miR-27a-3p in HCC and later transfected upregulated miR-27a-3p in mesenchymal stem cells, and treated HCC cells with exosomes extracted from the transfected stem cells. We then created mouse models of HCC using balbc/nude mice and equally treated them with exosomes from miR-27a-3p transfected stem cells. The results showed that miR-27a-3p is downregulated in blood, cell lines, and tissues of HCC patients compared to normal controls. Exosomes from the miR-27a-3p transfected mesenchymal stem cells prevented HCC cell proliferation, invasion, and metastasis both in vitro and in vivo. Upregulation of miR-27a-3p prevented HCC through interacting with and downregulating GOLM1 as its target oncogene. In conclusion, miR-27a-3p is a potential therapeutic target for HCC acting through GOLM1.

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.

Close-to-native bone repair via tissue-engineered endochondral ossification approaches

In order to solve the clinical challenges related to bone grafting, several tissue engineering (TE) strategies have been proposed to repair critical-sized defects. Generally, the classical TE approaches are designed to promote bone repair via intramembranous ossification. Although promising, strategies that direct the osteogenic differentiation of mesenchymal stem/stromal cells are usually characterized by a lack of functional vascular supply, often resulting in necrotic cores. A less explored alternative is engineering bone constructs through a cartilage-mediated approach, resembling the embryological process of endochondral ossification. The remodeling of an intermediary hypertrophic cartilaginous template triggers vascular invasion and bone tissue deposition. Thus, employing this knowledge can be a promising direction for the next generation of bone TE constructs. This review highlights the most recent biomimetic strategies for applying endochondral ossification in bone TE while discussing the plethora of cell types, culture conditions, and biomaterials essential to promote a successful bone regeneration process.

Bone marrow mesenchymal stem cells in premature ovarian failure: Mechanisms and prospects

Premature ovarian failure (POF) is a common female reproductive disorder and characterized by menopause, increased gonadotropin levels and estrogen deficiency before the age of 40 years old. The etiologies and pathogenesis of POF are not fully clear. At present, hormone replacement therapy (HRT) is the main treatment options for POF. It helps to ameliorate perimenopausal symptoms and related health risks, but can't restore ovarian function and fertility fundamentally. With the development of regenerative medicine, bone marrow mesenchymal stem cells (BMSCs) have shown great potential for the recovery of ovarian function and fertility based on the advantages of abundant sources, high capacity for self-renewal and differentiation, low immunogenicity and less ethical considerations. This systematic review aims to summarize the possible therapeutic mechanisms of BMSCs for POF. A detailed search strategy of preclinical studies and clinical trials on BMSCs and POF was performed on PubMed, MEDLINE, Web of Science and Embase database. A total of 21 studies were included in this review. Although the standardization of BMSCs need more explorations, there is no doubt that BMSCs transplantation may represent a prospective therapy for POF. It is hope to provide a theoretical basis for further research and treatment for POF.

Strategies to improve the effect of mesenchymal stem cell therapy on inflammatory bowel disease

Inflammatory bowel disease (IBD) includes Crohn’s disease and ulcerative colitis and is an idiopathic, chronic inflammatory disease of the colonic mucosa. The occurrence of IBD, causes irreversible damage to the colon and increases the risk of carcinoma. The routine clinical treatment of IBD includes drug treatment, endoscopic treatment and surgery. The vast majority of patients are treated with drugs and biological agents, but the complete cure of IBD is difficult. Mesenchymal stem cells (MSCs) have become a new type of cell therapy for the treatment of IBD due to their immunomodulatory and nutritional functions, which have been confirmed in many clinical trials. This review discusses some potential mechanisms of MSCs in the treatment of IBD, summarizes the experimental results, and provides new insights to enhance the therapeutic effects of MSCs in future applications.

Mesenchymal stromal cells: promising treatment for liver cirrhosis

Liver fibrosis is a wound-healing process that occurs in response to severe injuries and is hallmarked by the excessive accumulation of extracellular matrix or scar tissues within the liver. Liver fibrosis can be either acute or chronic and is induced by a variety of hepatotoxic causes, including lipid deposition, drugs, viruses, and autoimmune reactions. In advanced fibrosis, liver cirrhosis develops, a condition for which there is no successful therapy other than liver transplantation. Although liver transplantation is still a viable option, numerous limitations limit its application, including a lack of donor organs, immune rejection, and postoperative complications. As a result, there is an immediate need for a different kind of therapeutic approach. Recent research has shown that the administration of mesenchymal stromal cells (MSCs) is an attractive treatment modality for repairing liver injury and enhancing liver regeneration. This is accomplished through the cell migration into liver sites, immunoregulation, hepatogenic differentiation, as well as paracrine mechanisms. MSCs can also release a huge variety of molecules into the extracellular environment. These molecules, which include extracellular vesicles, lipids, free nucleic acids, and soluble proteins, exert crucial roles in repairing damaged tissue. In this review, we summarize the characteristics of MSCs, representative clinical study data, and the potential mechanisms of MSCs-based strategies for attenuating liver cirrhosis. Additionally, we examine the processes that are involved in the MSCs-dependent modulation of the immune milieu in liver cirrhosis. As a result, our findings lend credence to the concept of developing a cell therapy treatment for liver cirrhosis that is premised on MSCs. MSCs can be used as a candidate therapeutic agent to lengthen the survival duration of patients with liver cirrhosis or possibly reverse the condition in the near future.

Exploring the Immunomodulatory Aspect of Mesenchymal Stem Cells for Treatment of Severe Coronavirus Disease 19

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is an enveloped, positive sense, single stranded RNA (+ssRNA) virus, belonging to the genus Betacoronavirus and family Coronaviridae. It is primarily transmitted from infected persons to healthy ones through inhalation of virus-laden respiratory droplets. After an average incubation period of 2–14 days, the majority of infected individuals remain asymptomatic and/or mildly symptomatic, whereas the remaining individuals manifest a myriad of clinical symptoms, including fever, sore throat, dry cough, fatigue, chest pain, and breathlessness. SARS-CoV-2 exploits the angiotensin converting enzyme 2 (ACE-2) receptor for cellular invasion, and lungs are amongst the most adversely affected organs in the body. Thereupon, immune responses are elicited, which may devolve into a cytokine storm characterized by enhanced secretion of multitude of inflammatory cytokines/chemokines and growth factors, such as interleukin (IL)-2, IL-6, IL-7, IL-8, IL-9, tumor necrosis factor alpha (TNF-α), granulocyte colony-stimulating factor (GCSF), basic fibroblast growth factor 2 (bFGF2), monocyte chemotactic protein-1 (MCP1), interferon-inducible protein 10 (IP10), macrophage inflammatory protein 1A (MIP1A), platelet-derived growth factor subunit B (PDGFB), and vascular endothelial factor (VEGF)-A. The systemic persistence of inflammatory molecules causes widespread histological injury, leading to functional deterioration of the infected organ(s). Although multiple treatment modalities with varying effectiveness are being employed, nevertheless, there is no curative COVID-19 therapy available to date. In this regard, one plausible supportive therapeutic modality may involve administration of mesenchymal stem cells (MSCs) and/or MSC-derived bioactive factors-based secretome to critically ill COVID-19 patients with the intention of accomplishing better clinical outcome owing to their empirically established beneficial effects. MSCs are well established adult stem cells (ASCs) with respect to their immunomodulatory, anti-inflammatory, anti-oxidative, anti-apoptotic, pro-angiogenic, and pro-regenerative properties. The immunomodulatory capabilities of MSCs are not constitutive but rather are highly dependent on a holistic niche. Following intravenous infusion, MSCs are known to undergo considerable histological trapping in the lungs and, therefore, become well positioned to directly engage with lung infiltrating immune cells, and thereby mitigate excessive inflammation and reverse/regenerate damaged alveolar epithelial cells and associated tissue post SARS-CoV-2 infection. Considering the myriad of abovementioned biologically beneficial properties and emerging translational insights, MSCs may be used as potential supportive therapy to counteract cytokine storms and reduce disease severity, thereby facilitating speedy recovery and health restoration.

Matrix stiffness regulates the immunomodulatory effects of mesenchymal stem cells on macrophages via AP1/TSG-6 signaling pathways

It is well-recognized that the matrix stiffness as an important stem cell niche can mediate stem cell behavior such as attachment, proliferation and differentiation, but how matrix stiffness affects the immunomodulatory efficacy of stem cells has been little explored, which, however, is of significant importance in determining the outcomes of stem cell-based therapies and engineered tissue mimics. We herein studied the immunomodulatory efficacy of mesenchymal stem cells (MSCs) in response to matrix stiffness by the evaluation of macrophage polarization in vitro and inflammatory response in vivo by subcutaneous implantation of MSC-laden hydrogels. Remarkably, we found that soft matrix enabled MSCs to produce significantly higher levels of immunomodulatory factors compared to stiff matrix, and induced the presence of more anti-inflammatory macrophages in vitro and attenuated macrophages-mediated inflammatory response in vivo. More importantly, we revealed stiffness-mediated immunoregulatory effect of MSCs was mainly attributed to tumor necrosis factor-α-stimulated protein 6 (TSG-6), which was mechanosensitively regulated by the MAPK and Hippo signaling pathway and downstream AP1 complex, and which in turn exerted an effect on macrophages through CD44 receptor to inhibit NF-κB pathway. To conclude, our results for the first time identify TSG-6 as the key factor in regulating immunomodulatory efficacy of MSCs in mechanical response, and can be potentially utilized to empower stem cell-based therapy and tissue engineering strategy in regenerative medicine. STATEMENT OF SIGNIFICANCE: Matrix stiffness as an important stem cell niche can mediate stem cell behavior such as attachment and differentiation, but how matrix stiffness affects the immunomodulatory efficacy of stem cells has been little explored, which, however, is of significant importance in determining the outcomes of stem cell-based therapies and engineered tissue mimics. Our results for the first time identify TSG-6 as the key factor in regulating the immunomodulatory efficacy of MSCs in mechanical response, which was regulated by the MAPK and Hippo signaling pathways and downstream AP1 complex, and which in turn exerted an effect on macrophages through CD44 receptor to inhibit NF-κB pathway, and can be potentially utilized to empower stem cell-based therapy and tissue engineering strategy in regenerative medicine.

Therapeutic Strategy of Mesenchymal-Stem-Cell-Derived Extracellular Vesicles as Regenerative Medicine

Extracellular vesicles (EVs) are lipid bilayer membrane particles that play critical roles in intracellular communication through EV-encapsulated informative content, including proteins, lipids, and nucleic acids. Mesenchymal stem cells (MSCs) are pluripotent stem cells with self-renewal ability derived from bone marrow, fat, umbilical cord, menstruation blood, pulp, etc., which they use to induce tissue regeneration by their direct recruitment into injured tissues, including the heart, liver, lung, kidney, etc., or secreting factors, such as vascular endothelial growth factor or insulin-like growth factor. Recently, MSC-derived EVs have been shown to have regenerative effects against various diseases, partially due to the post-transcriptional regulation of target genes by miRNAs. Furthermore, EVs have garnered attention as novel drug delivery systems, because they can specially encapsulate various target molecules. In this review, we summarize the regenerative effects and molecular mechanisms of MSC-derived EVs.

Amelioration of aflatoxin acute hepatitis rat model by bone marrow mesenchymal stem cells and their hepatogenic differentiation

Background and Aim:

Bone marrow-derived mesenchymal stem cells (BM-MSCs) transplantation and their hepatogenic differentiated cells (HDCs) can be applied for liver injury repair by tissue grafting. Regenerative potentiality in liver cirrhosis models was widely investigated; however, immunomodulation and anti-inflammation in acute hepatitis remain unexplored. This study aimed to explore the immunomodulatory and evaluate twice intravenous (IV) or intrahepatic (IH) administration of either BM-MSCs or middle-stage HDCs on aflatoxin (AF) acute hepatitis rat model.

Materials and Methods:

BM-MSCs viability, phenotypes, and proliferation were evaluated. Hepatogenic differentiation, albumin, and mmmmmmmm-fetoprotein gene expression were assessed. AF acute hepatitis was induced in rats using AFB1 supplementation. The transplantation of BM-MSCs or their HDCs was done either by IV or IH route. Hepatic ultrasound was performed after 3-weeks of therapy. Cytokines profile (tumor necrosis factor-α [TNF-α], interleukin [IL]-4, and IL-10) was assessed. Hepatic bio-indices, serum, and hepatic antioxidant activity were evaluated, besides examining liver histological sections.

Results:

Acute AFB1 showed a significant increase in TNF-α (p<0.01), liver enzyme activities (p<0.05), as well as decrease in IL-4, IL-10, and antioxidant enzyme activities (p<0.05). Cytokines profile was ameliorated in groups treated with IV and IH BM-MCs, showed a negative correlation between IL-4 and TNF-α (p<0.05), and a positive correlation between IL-10 upregulation and TNF-α (p<0.01). In IV HDCs treated group, positive correlations between IL-4 and IL-10 downregulation and TNF-α were observed. However, in IH HDCs group, a significant positive correlation between IL-4 and IL-10 upregulation and TNF-α, were recorded (p<0.05). In addition, IV BM-MSCs and IH HDCs treatments significantly increased antioxidant enzymes activity (p<0.05). IV and IH BM-MSCs significantly ameliorated liver transaminase levels, whereas IH HDCs significantly ameliorated alanine aminotransferase activity and nitric oxide concentration (p<0.05).

Conclusion:

The administration routes of BM-MSCs did not demonstrate any significant difference; however, the IH route of HDCs showed significant amelioration from the IV route. On the other hand, it showed noticeable anti-inflammatory and immunomodulatory improvements in aflatoxicosis rats. Therefore, it can be concluded that acute hepatitis can be treated by a noninvasive IV route without the expense of hepatogenic differentiation. Further research using clinical trials that address several problems regarding engraftment and potentiation are needed to determine the optimal manipulation strategy as well as to achieve better long term effects.

Characteristics and regulation of mesenchymal stem cell plasticity by the microenvironment — specific factors involved in the regulation of MSC plasticity

Mesenchymal stem cells (MSCs), multipotent stromal cells, have attracted extensive attention in the field of regenerative medicine and cell therapy due to the capacity of self-renewal, multilineage differentiation, and immune regulation. MSCs have different cellular effects in different diseases, and even have markedly different curative effects with different tissue sources, indicating the plasticity of MSCs. The phenotypes, secreted factors, and proliferative, migratory, differentiating, and immunomodulatory effects of MSCs depend on certain mediators present in their microenvironment. Understanding microenvironmental factors and their internal mechanisms in MSC responses may help in subsequent prediction and improvement of clinical benefits. This review highlighted the recent advances in MSC plasticity in the physiological and pathological microenvironment and multiple microenvironmental factors regulating MSC plasticity. It also highlighted some progress in the underlying molecular mechanisms of MSC remodeling in the microenvironment. It might provide references for the improvement in vitro culture of MSCs, clinical application, and in vivo induction.

Stem cell therapy for COVID-19 pneumonia

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus is a highly contagious microorganism, and despite substantial investigation, no progress has been achieved in treating post-COVID complications. However, the virus has made various mutations and has spread around the world. Researchers have tried different treatments to reduce the side effects of the COVID-19 symptoms. One of the most common and effective treatments now used is steroid therapy to reduce the complications of this disease. Long-term steroid therapy for chronic inflammation following COVID-19 is harmful and increases the risk of secondary infection, and effective treatment remains challenging owing to fibrosis and severe inflammation and infection. Sometimes our immune system can severely damage ourselves in disease. In the past, many researchers have conducted various studies on the immunomodulatory properties of stem cells. This property of stem cells led them to modulate the immune system of autoimmune diseases like diabetes, multiple sclerosis, and Parkinson's. Because of their immunomodulatory properties, stem cell-based therapy employing mesenchymal or hematopoietic stem cells may be a viable alternative treatment option in some patients. By priming the immune system and providing cytokines, chemokines, and growth factors, stem cells can be employed to build a long-term regenerative and protective response. This review addresses the latest trends and rapid progress in stem cell treatment for Acute Respiratory Distress Syndrome (ARDS) following COVID-19.

Adipose-Derived Mesenchymal Stromal/Stem Cell Line Prevents Hepatic Ischemia/Reperfusion Injury in Rats by Inhibiting Inflammasome Activation

Mesenchymal stromal/stem cells (MSCs) have shown potential in the treatment of degenerative diseases, including ischemia/reperfusion injury (IRI), which occurs during organ transplantation and represents the main cause of post-transplant graft dysfunction. However, MSCs have heterogeneous characteristics, and studies of MSCs therapy have shown a variety of outcomes. To establish a new effective MSCs therapy, we developed an adipose-derived mesenchymal stromal/stem cell line (ASCL) and compared its therapeutic effects on primary adipose-derived MSCs (ASCs) using a hepatocyte co-culture model of hypoxia/reoxygenation in vitro and a rat model of hepatic IRI in vivo. The results showed that both ASCL and ASCs protect against hypoxia by improving hepatocyte viability, inhibiting reactive oxygen species release, and upregulating transforming growth factor-β in vitro. In vivo, ASCL or ASCs were infused into the spleen 24 h before the induction of rat hepatic IRI. The results showed that ASCL significantly improved the survival outcomes compared with the control (normal saline infusion) with the significantly decreased serum levels of liver enzymes and less damage to liver tissues compared with ASCs. Both ASCL and ASCs suppressed NOD-like receptor family pyrin domain-containing 3 inflammasome activation and subsequently reduced the release of activated IL-1β and IL-18, which is considered an important mechanism underlying ASCL and ASCs infusion in hepatic IRI. In addition, ASCL can promote the release of interleukin-1 receptor antagonist, which was previously reported as a key factor in hampering the inflammatory cascade during hepatic IRI. Our results suggest ASCL as a new candidate for hepatic IRI treatment due to its relatively homogeneous characteristics.

Therapeutic effects of CXCL9-overexpressing human umbilical cord mesenchymal stem cells on liver fibrosis in rats

Umbilical cord mesenchymal stem cells (UC-MSCs) transplantation has become a promising treatment for liver fibrosis. However, UC-MSCs have limited anti-fibrosis ability, and their homing ability of UC-MSCs to the injured liver seems to be poor. In our study, we aimed to determine if the CXCL9-overexpressing UC-MSCs could have synergistic anti-fibrosis effects and whether it can promote the homing ability of UC-MSCs. Overexpression of CXCL9 in UC-MSCs (CXCL9-UC-MSCs) was attained by transfecting the lenti-CXCL9-mCherry to naive UC-MSCs. The therapeutic effect of transducted CXCL9-UC-MSCs on both repairing of hepatic fibrosis and target homing were evaluated by comparing with the control of UC-MSCs transfected with empty lenti-mCherry vector. The results revealed that the liver function of CXCL9-UC-MSCs treated group was significantly improved when compared with that of control UC-MSCs (P < 0.05), and the histopathology indicated an obvious decrease of the collagen fiber content and significant disappearing of pseudo-lobules with basically normal morphology of hepatic lobules. Furthermore, liver frozen sections confirmed that CXCL9-UC-MSCs have significantly stronger chemotaxis and stable persistence in the injured liver tissues. In summary, overexpression of CXCL9 could improve the efficacy of UC-MSCs therapy for liver fibrosis repairing on account of an enhanced ability of UC-MSCs in homing to and staying in the injured sites of liver fibrosis in rat models.

Targeting Programmed Cell Death to Improve Stem Cell Therapy: Implications for Treating Diabetes and Diabetes-Related Diseases

Stem cell therapies have shown promising therapeutic effects in restoring damaged tissue and promoting functional repair in a wide range of human diseases. Generations of insulin-producing cells and pancreatic progenitors from stem cells are potential therapeutic methods for treating diabetes and diabetes-related diseases. However, accumulated evidence has demonstrated that multiple types of programmed cell death (PCD) existed in stem cells post-transplantation and compromise their therapeutic efficiency, including apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. Understanding the molecular mechanisms in PCD during stem cell transplantation and targeting cell death signaling pathways are vital to successful stem cell therapies. In this review, we highlight the research advances in PCD mechanisms that guide the development of multiple strategies to prevent the loss of stem cells and discuss promising implications for improving stem cell therapy in diabetes and diabetes-related diseases.

Co-administration of human MSC overexpressing HIF-1α increases human CD34+ cell engraftment in vivo

Background

Poor graft function or graft failure after allogeneic stem cell transplantation is an unmet medical need, in which mesenchymal stromal cells (MSC) constitute an attractive potential therapeutic approach. Hypoxia-inducible factor-1α (HIF-1α) overexpression in MSC (HIF-MSC) potentiates the angiogenic and immunomodulatory properties of these cells, so we hypothesized that co-transplantation of MSC-HIF with CD34⁺ human cord blood cells would also enhance hematopoietic stem cell engraftment and function both in vitro and in vivo.

Methods

Human MSC were obtained from dental pulp. Lentiviral overexpression of HIF-1α was performed transducing cells with pWPI-green fluorescent protein (GFP) (MSC WT) or pWPI-HIF-1α-GFP (HIF-MSC) expression vectors. Human cord blood CD34⁺ cells were co-cultured with MSC WT or HIF-MSC (4:1) for 72 h. Then, viability (Annexin V and 7-AAD), cell cycle, ROS expression and immunophenotyping of key molecules involved in engraftment (CXCR4, CD34, ITGA4, c-KIT) were evaluated by flow cytometry in CD34⁺ cells. In addition, CD34⁺ cells clonal expansion was analyzed by clonogenic assays. Finally, in vivo engraftment was measured by flow cytometry 4-weeks after CD34⁺ cell transplantation with or without intrabone MSC WT or HIF-MSC in NOD/SCID mice.

Results

We did not observe significant differences in viability, cell cycle and ROS expression between CD34⁺ cells co-cultured with MSC WT or HIF-MSC. Nevertheless, a significant increase in CD34, CXCR4 and ITGA4 expression (p = 0.009; p = 0.001; p = 0.013, respectively) was observed in CD34⁺ cells co-cultured with HIF-MSC compared to MSC WT. In addition, CD34⁺ cells cultured with HIF-MSC displayed a higher CFU-GM clonogenic potential than those cultured with MSC WT (p = 0.048). We also observed a significant increase in CD34⁺ cells engraftment ability when they were co-transplanted with HIF-MSC compared to CD34⁺ co-transplanted with MSC WT (p = 0.016) or alone (p = 0.015) in both the injected and contralateral femurs (p = 0.024, p = 0.008 respectively).

Conclusions

Co-transplantation of human CD34⁺ cells with HIF-MSC enhances cell engraftment in vivo. This is probably due to the ability of HIF-MSC to increase clonogenic capacity of hematopoietic cells and to induce the expression of adhesion molecules involved in graft survival in the hematopoietic niche.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02669-z.

Role of the Microenvironment in Mesenchymal Stem Cell-Based Strategies for Treating Human Liver Diseases

Liver disease is a severe health problem that endangers human health worldwide. Mesenchymal stem cell (MSC) therapy is a novel treatment for patients with different liver diseases due to its vast expansion potential and distinctive immunomodulatory properties. Despite several preclinical trials having confirmed the considerable efficacy of MSC therapy in liver diseases, the questionable safety and efficacy still limit its application. As a precursor cell, MSCs can adjust their characteristics in response to the surrounding microenvironment. The microenvironment provides physical and chemical factors essential for stem cell survival, proliferation, and differentiation. However, the mechanisms are still not completely understood. We, therefore, summarized the mechanisms underlying the MSC immune response, especially the interaction between MSCs and the liver microenvironment, discussing how to achieve better therapeutic effects.

Regulatory T Cells Improved the Anti-cirrhosis Activity of Human Amniotic Mesenchymal Stem Cell in the Liver by Regulating the TGF-β-Indoleamine 2,3-Dioxygenase Signaling

Liver fibrosis is a progression stage of chronic liver disease, while current therapies cannot cure or attune cirrhosis effectively. Human amniotic mesenchymal stromal cell (hAMSC) presented immunoregulatory and tissue repairability of multiple illnesses. Regulatory T cells (Treg) had been proved to be functional in reducing immune cell activity. We showed that co-infusion of hAMSC and Treg prevented mild liver fibrosis comparing with hAMSC or Treg alone group. In vitro study indicated that the addition of Treg or the supernatant of Treg improved the hepatocyte growth factor (HGF) secreting and cell differentiation ability of hAMSC. Reduction of TGF-β significantly decreased the HGF secreting and differentiation of hAMSC. Multiple signal neutralizers were added to the culture to understand further the mechanism, which showed that 1-MT, the suppressor of Indoleamine 2,3-dioxygenase (IDO), was involved in the effect of TGF-β in regulating hAMSC. Depletion of TGF-β or IDO signaling successfully abolished the effect of Treg in improving hAMSC's function both in vitro and vivo. Finally, our result indicated that Treg improved the function of hAMSC by regulating the TGF-β-IDO signaling and co-infusion of hAMSC and Treg provided a promising approach for treating liver cirrhosis.

Human hepatocyte-derived extracellular vesicles attenuate the carbon tetrachloride-induced acute liver injury in mice

Acute liver injury (ALI) induced by chemicals or viruses can progress rapidly to acute liver failure (ALF), often resulting in death of patients without liver transplantation. Since liver transplantation is limited due to a paucity of donors, expensive surgical costs, and severe immune rejection, novel therapies are required to treat liver injury. Extracellular vesicles (EVs) are used for cellular communication, carrying RNAs, proteins, and lipids and delivering them intercellularly after being endocytosed by target cells. Recently, it was reported that EVs secreted from human hepatocytes have an ability to modulate the immune responses; however, these roles of EVs secreted from human hepatocytes were studied only with in vitro experiments. In the present study, we evidenced that EVs secreted from human hepatocytes attenuated the CCL₄-induced ALI by inhibiting the recruitment of monocytes through downregulation of chemokine receptor in the bone marrow and recruitment of neutrophils through the reduction of C-X-C motif chemokine ligand 1 (CXCL1) and CXCL2 expression levels in the liver.

Physiologic isolation and expansion of human mesenchymal stem/stromal cells for manufacturing of cell‐based therapy products

The utilization of mesenchymal stem/stromal cells raises new hopes in treatment of diseases and pathological conditions, while at the same time bringing immense challenges for researchers, manufacturers and physicians. It is essential to consider all steps along the in vitro fabrication of cell‐based products in order to reach efficient and reproducible treatment outcomes. Here, the optimal protocols for isolation, cultivation and differentiation of mesenchymal stem cells are required. In this review we discuss these aspects and their influence on the final cell‐based product quality. We demonstrate that physiological in vitro cell cultivation conditions play a crucial role in therapeutic functionalities of cultivated cells. We show that three‐dimensional cell culture, dynamic culture conditions and physiologically relevant in vitro oxygen concentrations during isolation and expansion make a decisive contribution towards the improvement of cell‐based products in regenerative medicine.

Regulation of autophagy protects against liver injury in liver surgery-induced ischaemia/reperfusion

Transient ischaemia and reperfusion in liver tissue induce hepatic ischaemia/reperfusion (I/R) tissue injury and a profound inflammatory response in vivo. Hepatic I/R can be classified into warm I/R and cold I/R and is characterized by three main types of cell death, apoptosis, necrosis and autophagy, in rodents or patients following I/R. Warm I/R is observed in patients or animal models undergoing liver resection, haemorrhagic shock, trauma, cardiac arrest or hepatic sinusoidal obstruction syndrome when vascular occlusion inhibits normal blood perfusion in liver tissue. Cold I/R is a condition that affects only patients who have undergone liver transplantation (LT) and is caused by donated liver graft preservation in a hypothermic environment prior to entering a warm reperfusion phase. Under stress conditions, autophagy plays a critical role in promoting cell survival and maintaining liver homeostasis by generating new adenosine triphosphate (ATP) and organelle components after the degradation of macromolecules and organelles in liver tissue. This role of autophagy may contribute to the protection of hepatic I/R‐induced liver injury; however, a considerable amount of evidence has shown that autophagy inhibition also protects against hepatic I/R injury by inhibiting autophagic cell death under specific circumstances. In this review, we comprehensively discuss current strategies and underlying mechanisms of autophagy regulation that alleviates I/R injury after liver resection and LT. Directed autophagy regulation can maintain liver homeostasis and improve liver function in individuals undergoing warm or cold I/R. In this way, autophagy regulation can contribute to improving the prognosis of patients undergoing liver resection or LT.

The impact of recipient age on the effects of umbilical cord mesenchymal stem cells on HBV-related acute-on-chronic liver failure and liver cirrhosis

Background

The results of a previous study verified that umbilical cord mesenchymal stem cells (UCMSCs) have good therapeutic effects for the treatment of HBV-related acute-on-chronic liver failure (ACLF) and liver cirrhosis (LC). Nevertheless, it is still unknown whether the effects of UCMSCs are affected by recipient age.

Methods

Patients treated with UCMSCs who met the criteria of HBV-related ACLF and liver cirrhosis were identified in this retrospective observational study. Patients were divided into subgroups according to the World Health Organization (WHO) age criteria (< 45 vs. ≥ 45 years). Group A included young ACLF patients (< 45 y), and group B included older ACLF patients (≥ 45 y). Young LC patients (< 45 y) were assigned to group C, and group D included older LC patients (≥ 45 y). Patients’ clinical characteristics, demographics, biochemical factors, and model for end-stage liver disease (MELD) scores were compared for 24 weeks.

Results

Sixty-four ACLF patients and 59 LC patients were enrolled in this study. Compared with patients in groups B and C, patients in group A did not show significant superiority in terms of the levels of ALT, AST, TBIL, AFP, and PTA and MELD scores. However, the median decrease and cumulative decrease in the TBIL and ALT levels of patients in group C were larger than those of patients in group D after four weeks of UCMSC transfusions. For older patients (≥ 45 y), the cumulative decrease and the median decrease in the TBIL of ACLF patients were significantly greater than those of LC patients after UCMSC treatment. However, the median decrease in ALT levels of ACLF patients was significantly greater than that of LC patients during UCMSC treatment, and the cumulative decrease in ALT levels of ACLF patients was significantly greater than that of LC patients at all time points.

Conclusion

The therapeutic effects of UCMSCs for HBV-related acute-on-chronic liver failure and liver cirrhosis varied partly by patient age. Assessing patient age is necessary prior to UCMSC clinical use.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02544-x.

The Application of Mesenchymal Stem Cells in the Treatment of Liver Diseases: Mechanism, Efficacy, and Safety Issues

Mesenchymal stem cell (MSC) transplantation is a novel treatment for liver diseases due to the roles of MSCs in regeneration, fibrosis inhibition and immune regulation. However, the mechanisms are still not completely understood. Despite the significant efficacy of MSC therapy in animal models and preliminary clinical trials, issues remain. The efficacy and safety of MSC-based therapy in the treatment of liver diseases remains a challenging issue that requires more investigation. This article reviews recent studies on the mechanisms of MSCs in liver diseases and the associated challenges and suggests potential future applications.

Enhancing therapeutic effects and in vivo tracking of adipose tissue-derived mesenchymal stem cells for liver injury using bioorthogonal click chemistry

Adipose tissue-derived mesenchymal stem cell (ADSC)-based therapy is attractive for liver diseases, but the long-term therapeutic outcome is still far from satisfaction due to the low hepatic engraftment efficiency of ADSC transplantation. Herein, we propose a strategy based on liver sinusoidal endothelial cell (LSEC)-targeting peptide modification and near infrared (NIR) fluorescent probe labeling for enhancing LSEC-barrier-migration ability and in vivo tracking of ADSCs in a liver injury mouse model. RLTRKRGLK (RK), a LSEC-targeted peptide, and indocyanine green (ICG), a FDA approved infrared fluorescent dye, were simultaneously modified on the ADSC surface via a bioorthogonal click reaction. The equipped ADSCs not only exhibited significant binding ability towards LSEC both in vitro and in vivo, but could also be monitored by NIR imaging in vivo. In particular, the RK-modified ADSCs showed remarkable higher hepatic accumulation as compared to unmodified ADSCs, resulting in better therapeutic outcomes. Therefore, this study provides a simple and convenient method for enhancing the homing of transplanted ADSCs to injured liver accompanying with in vivo cell tracking ability, which may shed light on accelerating the clinical translation of the ADSC-based therapy for liver diseases.

Cholangiogenic potential of human deciduous pulp stem cell-converted hepatocyte-like cells

Background

Stem cells from human exfoliated deciduous teeth (SHED) have been reported to show the in vivo and in vitro hepatic differentiation, SHED-Heps; however, the cholangiogenic potency of SHED-Heps remains unclear. Here, we hypothesized that SHED-Heps contribute to the regeneration of intrahepatic bile duct system in chronic fibrotic liver.

Methods

SHED were induced into SHED-Heps under cytokine stimulation. SHED-Heps were intrasplenically transplanted into chronically CCl₄-treated liver fibrosis model mice, followed by the analysis of donor integration and hepatobiliary metabolism in vivo. Immunohistochemical assay was examined for the regeneration of intrahepatic bile duct system in the recipient liver. Furthermore, SHED-Heps were induced under the stimulation of tumor necrosis factor alpha (TNFA).

Results

The intrasplenic transplantation of SHED-Heps into CCl₄-treated mice showed that donor SHED-Heps behaved as human hepatocyte paraffin 1- and human albumin-expressing hepatocyte-like cells in situ and ameliorated CCl₄-induced liver fibrosis. Of interest, the integrated SHED-Heps not only expressed biliary canaliculi ATP-binding cassette transporters including ABCB1, ABCB11, and ABCC2, but also recruited human keratin 19- (KRT19-) and KRT17-positive cells, which are considered donor-derived cholangiocytes, regenerating the intrahepatic bile duct system in the recipient liver. Furthermore, the stimulation of TNFA induced SHED-Heps into KRT7- and SRY-box 9-positive cells.

Conclusions

Collectively, our findings demonstrate that infused SHED-Heps showed cholangiogenic ability under the stimulation of TNFA in CCl₄-damaged livers, resulting in the regeneration of biliary canaliculi and interlobular bile ducts in chronic fibrotic liver. Thus, the present findings suggest that SHED-Heps may be a novel source for the treatment of cholangiopathy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-020-02113-8.

Applications of Mesenchymal Stem Cells in Liver Fibrosis: Novel Strategies, Mechanisms, and Clinical Practice

Liver fibrosis is a common result of most chronic liver diseases, and advanced fibrosis often leads to cirrhosis. Currently, there is no effective treatment for liver cirrhosis except liver transplantation. Therefore, it is important to carry out antifibrosis treatment to reverse liver damage in the early stage of liver fibrosis. Mesenchymal stem cells (MSCs) are the most widely used stem cells in the field of regenerative medicine. The preclinical and clinical research results of MSCs in the treatment of liver fibrosis and cirrhosis show that MSC administration is a promising treatment for liver fibrosis and cirrhosis. MSCs reverse liver fibrosis and increase liver function mainly through differentiation into hepatocytes, immune regulation, secretion of cytokines and other nutritional factors, reduction of hepatocyte apoptosis, and promotion of hepatocyte regeneration. Recently, many studies provided a variety of new methods and strategies to improve the effect of MSCs in the treatment of liver fibrosis. In this review, we summarized the current effective methods and strategies and their potential mechanisms of MSCs in the treatment of liver fibrosis, as well as the current research progress in clinical practice. We expect to achieve complete reversal of liver injury with MSC-based therapy in the future.

Urine-derived stem cells accelerate the recovery of injured mouse hepatic tissue

Urine-derived stem cells (USCs) are autologous stem cells that exhibit self-renewal ability and multi-lineage differentiation potential. These characteristics make USCs an ideal cell source for hepatocellular transplantation. Here, we investigated the biological characteristics of USCs and their potential use for the treatment of chronic liver injury. We characterized the cell-surface marker profile of USCs by flow cytometry and determined the osteogenic, adipogenic, and hepatic differentiation capacities of USCs using histology. We established a chronic liver-injury model by intraperitoneally injecting carbon tetrachloride into nude mice. USCs were then transplanted via tail vein injection. To determine liver function and histopathology following chronic liver injury, we calculated the liver index, measured serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, and performed histological staining. USCs were small, adherent cells expressing mesenchymal but not hematopoietic stem-cell markers. Some induced USCs underwent osteogenic and adipogenic differentiation. When co-cultured with hepatic progenitor cells, about 10% of USCs underwent hepatic differentiation. The ALT and AST levels of the USC-transplanted group were lower than that of the chronic liver-injury model group, and there were no significant differences between the two USC-transplanted groups. However, hepatocyte degeneration and liver fibrosis substantially improved in the hypoxia-pretreated USC-transplanted group compared with the normoxia USC-transplanted group. Taken together, USCs display desirable proliferation and differentiation characteristics, and USC transplantation partially improves abnormal liver function and pathology associated with chronic liver injury. Furthermore, hypoxia pretreatment promotes cell proliferation, migration, and colony formation by inducing autophagy, leading to USC-elicited liver tissue recovery following injury in vivo.

IL-1β Pretreatment Improves the Efficacy of Mesenchymal Stem Cells on Acute Liver Failure by Enhancing CXCR4 Expression

BACKGROUND

Mesenchymal stem cells (MSCs), with the powerful metabolic and functional supporting abilities for inflammatory diseases, may be an effective therapeutic strategy for acute liver failure (ALF). However, the efficacy of MSCs can still be promoted if pretreatment is applied to enhance their poor migration towards the damaged liver. The purpose of this study is to determine the effect of IL-1β pretreatment on the efficacy and homing ability of MSCs in ALF.

METHODS

MSCs were isolated by the whole bone marrow adherence method and characterized. The efficacy and homing ability of IL-1β-pretreated MSCs (Pre-MSCs) were examined in a rat ALF model and compared with that of MSCs and normal saline. Then, Western blot was performed to detect the c-Met and CXCR4 expression of MSCs and Pre-MSCs and followed by flow cytometry to detect the meaningful indicators. Finally, the migration abilities of different cells and different conditions were tested by the Transwell migration assay.

RESULTS

MSCs of ideal purity were successfully isolated and cultured. Comparing with MSCs, Pre-MSCs had significantly better efficacy on improving the survival rate and liver function of ALF rats. Further analyses of damaged liver tissues showed that IL-1β pretreatment significantly enhanced the efficacy of MSCs on suppressing liver necrosis. Besides, Pre-MSCs exhibited better effects in inhibiting apoptosis and activating proliferation. The results of tracing experiments with CM-Dil-labeled cells confirmed that more cells migrated to the damaged liver in the Pre-MSC group. In terms of mechanism, the CXCR4 expression was significantly enhanced by IL-1β pretreatment, and an increased migration ability towards SDF-1 that could be reversed by AMD3100 was found in Pre-MSCs.

CONCLUSION

IL-1β pretreatment could enhance the homing ability of MSCs at least partially by increasing the expression of CXCR4 and further improve the efficacy of MSCs on ALF.

Exosomes released from educated mesenchymal stem cells accelerate cutaneous wound healing via promoting angiogenesis

Objectives

Skin serves as the major interface between the external environment and body which is liable to many kinds of injuries. Mesenchymal stem cell (MSC) therapy has been widely used and became a promising strategy. Pre‐treatment with chemical agents, hypoxia or gene modifications can partially protect MSCs against injury, and the pre‐treated MSCs show the improved differentiation, homing capacity, survival and paracrine effects regard to attenuating injury. The aim of this study was to investigate whether the exosomes from the educated MSCs contribute to accelerate wound healing process.

Materials and methods

We extracted the exosomes from the two educated MSCs and utilized them in the cutaneous wound healing model. The pro‐angiogenetic effect of exosomes on endothelial cells was also investigated.

Results

We firstly found that MSCs pre‐treated by exosomes from neonatal serum significantly improved their biological functions and the effect of therapy. Moreover, we extracted the exosomes from the educated MSCs and utilized them to treat the cutaneous wound model directly. We found that the released exosomes from MSCs which educated by neonatal serum before had the more outstanding performance in therapeutic effect. Mechanistically, we revealed that the recipient endothelial cells (ECs) were targeted and the exosomes promoted their functions to enhance angiogenesis via regulating AKT/eNOS pathway.

Conclusions

Our findings unravelled the positive effect of the upgraded exosomes from the educated MSCs as a promising cell‐free therapeutic strategy for cutaneous wound healing.

Pre-treatments enhance the therapeutic effects of mesenchymal stem cells in liver diseases

Liver diseases caused by viral infection, alcohol abuse and metabolic disorders can progress to end‐stage liver failure, liver cirrhosis and liver cancer, which are a growing cause of death worldwide. Although liver transplantation and hepatocyte transplantation are useful strategies to promote liver regeneration, they are limited by scarce sources of organs and hepatocytes. Mesenchymal stem cells (MSCs) restore liver injury after hepatogenic differentiation and exert immunomodulatory, anti‐inflammatory, antifibrotic, antioxidative stress and antiapoptotic effects on liver cells in vivo. After isolation and culture in vitro, MSCs are faced with nutrient and oxygen deprivation, and external growth factors maintain MSC capacities for further applications. In addition, MSCs are placed in a harsh microenvironment, and anoikis and inflammation after transplantation in vivo significantly decrease their regenerative capacity. Pre‐treatment with chemical agents, hypoxia, an inflammatory microenvironment and gene modification can protect MSCs against injury, and pre‐treated MSCs show improved hepatogenic differentiation, homing capacity, survival and paracrine effects in vitro and in vivo in regard to attenuating liver injury. In this review, we mainly focus on pre‐treatments and the underlying mechanisms for improving the therapeutic effects of MSCs in various liver diseases. Thus, we provide evidence for the development of MSC‐based cell therapy to prevent acute or chronic liver injury. Mesenchymal stem cells have potential as a therapeutic to prolong the survival of patients with end‐stage liver diseases in the near future.