Up-regulation of CXCR4 in rat umbilical mesenchymal stem cells induced by serum from rat with acute liver failure promotes stem cells migration to injured liver tissue

Unveiling heterogeneity in MSCs: exploring marker-based strategies for defining MSC subpopulations

Mesenchymal stem/stromal cells (MSCs) represent a heterogeneous cell population distributed throughout various tissues, demonstrating remarkable adaptability to microenvironmental cues and holding immense promise for disease treatment. However, the inherent diversity within MSCs often leads to variability in therapeutic outcomes, posing challenges for clinical applications. To address this heterogeneity, purification of MSC subpopulations through marker-based isolation has emerged as a promising approach to ensure consistent therapeutic efficacy. In this review, we discussed the reported markers of MSCs, encompassing those developed through candidate marker strategies and high-throughput approaches, with the aim of explore viable strategies for addressing the heterogeneity of MSCs and illuminate prospective research directions in this field.

Mesenchymal Stem Cell Therapy in Acute Liver Failure

Acute liver failure (ALF) is a severe liver disease syndrome with rapid deterioration and high mortality. Liver transplantation is the most effective treatment, but the lack of donor livers and the high cost of transplantation limit its broad application. In recent years, there has been no breakthrough in the treatment of ALF, and the application of stem cells in the treatment of ALF is a crucial research field. Mesenchymal stem cells (MSCs) are widely used in disease treatment research due to their abundant sources, low immunogenicity, and no ethical restrictions. Although MSCs are effective for treating ALF, the application of MSCs to ALF needs to be further studied and optimized. In this review, we discuss the potential mechanisms of MSCs therapy for ALF, summarize some methods to enhance the efficacy of MSCs, and explore optimal approaches for MSC transplantation.

Down-Regulation of CXCR4 in Mesenchymal Stem Cells by Septic Serum

Background

Sepsis is one of the main concerns of health and one of the leading causes of death in hospitals. It is essential to manage sepsis in hospitalized patients. In recent years, cell therapy has been considered as a new approach to treat sepsis. This study evaluated the effect of CXCR4 as one of the main proteins involved in the homing of mesenchymal stem cells in the sepsis serum in mice model.

Methods

Mouse sepsis model was induced by injection of E.coli and biochemical analyses was done to confirm the organ failure. Mesenchymal stem cells (MSCs) derived from bone marrow were separated into sepsis and control groups. In the sepsis serum group, MSCs were treated with sepsis serum at two time points: 24 and 48 h. Quantitative RT-PCR and flow cytometry were performed to determine the mRNA expression of CXCR4 in sepsis serum group compared to control group. Also, a migration assay was done to assess the migration capacity of bone marrow MSCs during inflammation and treatment in sepsis.

Results

Our result showed that treatment with sepsis serum can control migration by decrease in CXCR4 level (P ≤ 0.05) compared to control group. Moreover it was also reported that sepsis serum decreased mRNA expression of CXCR4 in MScs.

Conclusions

In our study, MSCs treated with septic serum were no longer able to migrate . Probably many variables such as source, dose, injection time, and injection route of MSCs after sepsis induction in the animal models are key factors for successful cell therapy.

CCR9 axis inhibition enhances hepatic migration of plasmacytoid dendritic cells and protects against liver injury

Plasmacytoid dendritic cells (pDCs) perform dual proinflammatory and immunosuppressive roles. We recently reported the potential of pDC therapy for treatment of intractable acute liver failure. However, establishment of efficient methods to deliver pDCs to the liver is essential for future clinical therapeutic applications. The present study demonstrates a higher abundance of liver and peripheral blood pDCs in mice lacking the C-C motif chemokine receptor 9 (CCR9), a pDC gut-homing receptor, than that in wild-type (WT) mice. Adoptive pDC transfer resulted in a higher efficiency of Ccr9-/- pDC migration to the liver than that to the original target organ, the small intestine, compared with that of WT pDCs. Further, Ccr9-/- pDCs consistently migrated efficiently to the concanavalin A-induced inflamed liver, and exerted a more effective immunosuppressive effect, resulting in better protection against acute liver inflammation than that demonstrated by WT pDCs. These findings highlight the therapeutic potential of the manipulation of CCR9 axis as a novel approach to improve migration of immunosuppressive pDCs to the liver in order to exploit their beneficial effects in acute liver disease.

Emerging Importance of Chemokine Receptor CXCR4 and Its Ligand in Liver Disease

Chemokine receptors are members of the G protein-coupled receptor superfamily, which together with chemokine ligands form chemokine networks to regulate various cellular functions, immune and physiological processes. These receptors are closely related to cell movement and thus play a vital role in several physiological and pathological processes that require regulation of cell migration. CXCR4, one of the most intensively studied chemokine receptors, is involved in many functions in addition to immune cells recruitment and plays a pivotal role in the pathogenesis of liver disease. Aberrant CXCR4 expression pattern is related to the migration and movement of liver specific cells in liver disease through its cross-talk with a variety of significant cell signaling pathways. An in-depth understanding of CXCR4-mediated signaling pathway and its role in liver disease is critical to identifying potential therapeutic strategies. Current therapeutic strategies for liver disease mainly focus on regulating the key functions of specific cells in the liver, in which the CXCR4 pathway plays a crucial role. Multiple challenges remain to be overcome in order to more effectively target CXCR4 pathway and identify novel combination therapies with existing strategies. This review emphasizes the role of CXCR4 and its important cell signaling pathways in the pathogenesis of liver disease and summarizes the targeted therapeutic studies conducted to date.

Downregulation of augmenter of liver regeneration impairs the therapeutic efficacy of liver epithelial progenitor cells against acute liver injury by enhancing mitochondrial fission

Cell-based therapeutic approaches have been proven to be effective strategies for the treatment of acute liver injury (ALI). However, widespread application of these procedures is limited by several key issues, including rapid loss of stemness in vitro, aberrant differentiation into undesirable cell types, and low engraftment in vivo. In this study, liver epithelial progenitor cells (LEPCs) were characterized and transfected with augmenter of liver regeneration (ALR). The results revealed that in ALI mice with CCl₄ , the transplantation of ALR-bearing LEPCs into the liver markedly protected mice against ALI by decreasing the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), thus relieving hepatic tissue injury and attenuating inflammatory infiltration. Mechanistically, the knockdown of ALR in LEPCs activated the phosphorylation of dynamin-related protein 1 (Drp1) at the S616 site and thereby enhanced mitochondrial fission. In contrast, the transfection of ALR into LEPCs significantly inhibited Drp1 phosphorylation, thereby favoring the maintenance of mitochondrial integrity and the preservation of adenosine triphosphate contents in LEPCs. Consequently, the ALR-bearing LEPCs transplanted into ALI mice exhibited substantially greater homing ability to the injured liver via the SDF-1/CXCR4 axis than that of LEPCs-lacking ALR. In conclusion, we demonstrated that the transplantation of ALR-transfected LEPCs protected mice against CCl₄ -induced ALI, thus offering immense curative potential in the clinic.

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.

Progress in mesenchymal stem cell-based therapy for acute liver failure

Acute liver failure is a life-threatening clinical syndrome characterized by rapid development of hepatocellular necrosis leading to high mortality and resource costs. Numerous treatment strategies for acute liver failure simply prevent complications and decelerate disease progression. The only curative treatment for acute liver failure is liver transplantation, but there are many restrictions on the application of liver transplantation. In recent years, a growing number of studies have shown that stem cells can effectively treat acute liver failure. Several types of stem cells have been used to study liver diseases; mesenchymal stem cells are most commonly used because they are easy to obtain and present no ethical problems. The aims of this article are to review the current knowledge regarding therapeutic mechanisms of mesenchymal stem cells in acute liver failure, to discuss recent advancements in preclinical and clinical studies in the treatment of mesenchymal stem cells, and to summarize the methodological improvement of mesenchymal stem cell transplantation in treating liver failure.

Stroke Induces Mesenchymal Stem Cell Migration to Infarcted Brain Areas Via CXCR4 and C-Met Signaling

Mesenchymal stem cells circulate between organs to repair and maintain tissues. Mesenchymal stem cells cultured with fetal bovine serum have therapeutic effects when intravenously administered after stroke. However, only a small number of mesenchymal stem cells reach the brain. We hypothesized that the serum from stroke patients increases mesenchymal stem cells trophism toward the infarcted brain area. Mesenchymal stem cells were grown in fetal bovine serum, normal serum from normal rats, or stroke serum from ischemic stroke rats. Compared to the fetal bovine serum group, the stroke serum group but not the normal serum group showed significantly greater migration toward the infarcted brain area in the in vitro and in vivo models (p < 0.05). Both C-X-C chemokine receptor type 4 and c-Met expression levels significantly increased in the stroke serum group than the others. The enhanced mesenchymal stem cells migration of the stroke serum group was abolished by inhibition of signaling. Serum levels of chemokines, cytokines, matrix metalloproteinase, and growth factors were higher in stroke serum than in normal serum. Behavioral tests showed a significant improvement in the recovery after stroke in the stroke serum group than the others. Stroke induces mesenchymal stem cells migration to the infarcted brain area via C-X-C chemokine receptor type 4 and c-Met signaling. Culture expansion using the serum from stroke patients could constitute a novel preconditioning method to enhance the therapeutic efficiency of mesenchymal stem cells.

Transplantation of Adipose-Derived Mesenchymal Stem Cells Efficiently Rescues Thioacetamide-Induced Acute Liver Failure in Mice

BACKGROUND

We aimed to investigate the efficacy of adipose-derived mesenchymal stem cell (ADMSC) transplantation in acute liver failure caused by thioacetamide in mice as well as its underlying mechanism by comparing transplantation routes.

METHODS

ADMSCs were isolated from inguinal fat pads of enhanced green fluorescent protein (EGFP) transgenic mice and analyzed regarding their surface markers and differentiation potential. Acute liver failure models were established by infusion of thioacetamide, and then we injected EGFP-ADMSCs or phosphate-buffered saline solution by intrasplenic or intravenous route. The restoration of biologic functions of the livers receiving transplantation was assessed by means of a variety of approaches, such as survival rates, live function parameters, histology, localization of EGFP-ADMSCs, and immunofluorescence analysis.

RESULTS

ADMSCs were positive for CD90 and CD44 and negative for CD34 and had adipogenic and osteogenic differentiation potential. And they prevented the release of liver injury biomarkers. Transplantation via tail vein provided a significant survival benefit, but no significant differences were observed in the intrasplenic pathway and between the 2 pathways in our animal experiments. Furthermore, the transplanted cells were well integrated into injured livers and produced albumin and cytokeratin-8.

CONCLUSIONS

Direct transplantation of ADMSCs is an effective treatment for acute liver failure rather than intrasplenic transplantation. The transplanted ADMSCs exhibit the potential to differentiate into hepatocyte-like cells in the injured livers. Thus, ADCMSCs would be a potential option for treatment of acute liver failure.

Pathology-targeted cell delivery via injectable micro-scaffold capsule mediated by endogenous TGase

Targeted cell delivery to lesion sites via minimally invasive approach remains an unmet need in regenerative medicine to endow satisfactory therapeutic efficacy and minimized side-effects. Here, we rationally designed a pathology-targeted cell delivery strategy leveraging injectable micro-scaffolds as cell-loading capsule and endogenous tissue transglutaminase (TGase) at lesion site as adhesive. Up-regulated TGase post-liver injury catalyzed chemical bonding between the glutamine and lysine residues on liver surface and micro-scaffolds both ex vivo and in vivo, facilitating sufficient adhesion on the pathological liver. Upon intraperitoneal injection, Mesenchymal Stem Cell-loaded capsules, exhibiting cell protection from shear-induced damage and post-transplantation anoikis, adhered to the CCl₄-treated liver with a hundred-fold improvement in targeting efficiency (70.72%) compared to free-cell injection, which dramatically improved mice survival (33.3% vs. 0% for free-cell therapy) even with low-dosage treatment. This unique and widely-applicable cell delivery mechanism and strategy hold great promise for transforming cell therapy for refractory diseases.

Intraportal mesenchymal stem cell transplantation prevents acute liver failure through promoting cell proliferation and inhibiting apoptosis

BACKGROUND

Transplantation of mesenchymal stem cells (MSCs) has been regarded as a potential treatment for acute liver failure (ALF), but the optimal route was unknown. The present study aimed to explore the most effective MSCs transplantation route in a swine ALF model.

METHODS

The swine ALF model induced by intravenous injection of D-Gal was treated by the transplantation of swine MSCs through four routes including intraportal injection (InP group), hepatic intra-arterial injection (AH group), peripheral intravenous injection (PV group) and intrahepatic injection (IH group). The living conditions and survival time were recorded. Blood samples before and after MSCs transplantation were collected for the analysis of hepatic function. The histology of liver injury was interpreted and scored in terminal samples. Hepatic apoptosis was detected by TUNEL assay. Apoptosis and proliferation related protein expressions including cleaved caspase-3, survivin, AKT, phospho-AKT (Ser473), ERK and phospho-ERK (Tyr204) were analyzed by Western blotting.

RESULTS

The average survival time of each group was 10.7+/-1.6 days (InP), 6.0+/-0.9 days (AH), 4.7+/-1.4 days (PV), 4.3+/-0.8 days (IH), respectively, when compared with the average survival time of 3.8+/-0.8 days in the D-Gal group. The survival rates between the InP group and D-Gal group revealed a statistically significant difference (P<0.01). Pathological and biochemical analysis showed that liver damage was the worst in the D-Gal group, while less injury in the InP group. Histopathological scores revealed a significant decrease in the InP group (3.17+/-1.04, P<0.01) and AH group (8.17+/-0.76, P<0.05) as compared with that in the D-Gal group (11.50+/-1.32). The apoptosis rate in the InP group (25.0%+/-3.4%, P<0.01) and AH group (40.5%+/-1.0%, P<0.05) was lower than that in the D-Gal group (70.6%+/-8.5%). The expression of active caspase-3 was inhibited, while the expression of survivin, AKT, phospho-AKT (Ser473), ERK and phospho-ERK (Tyr204) was elevated in the InP group.

CONCLUSIONS

Intraportal injection was superior to other pathways for MSC transplantation. Intraportal MSC transplantation could improve liver function, inhibit apoptosis and prolong the survival time of swine with ALF. The transplanted MSCs may participate in liver regeneration via promoting cell proliferation and suppressing apoptosis during the initial stage of ALF.

Neurosphere formation enhances the neurogenic differentiation potential and migratory ability of umbilical cord-mesenchymal stromal cells

BACKGROUND AIMS

The human umbilical cord (UC) is a rich source of mesenchymal stromal cells (MSCs), which have been reported to have multi-lineage potential. The objectives of this study were to investigate the characteristics and capacity of UC-MSC neurosphere formation and whether this event enhances the propensity of UC-MSCs to undergo neural differentiation.

METHODS

UC-MSCs were collected by the improved explant method. UC-MSCs and neurosphere-forming UC-MSCs (UC-MSC-neurospheres) were induced to undergo neurogenic differentiation, the latter of which were induced by suspension culturing in the presence of epidermal growth factor and basic fibroblast growth factor. The differentiation and migratory capacities of the individual cultures were then compared on the basis of the expression of neural markers, as measured by immunocytochemistry, immunoblotting and quantitative real-time polymerase chain reaction and transwell assays, respectively.

RESULTS

Both UC-MSCs and UC-MSC-neurospheres were capable of differentiating into neurogenic cells when cultured in neurogenic differentiation medium. However, pre-conditioned UC-MSC-neurospheres exhibited significantly higher expression of neural markers--including microtubule-associated protein (MAP2), MUSASHI1, glial fibrillary acidic protein (GFAP), and NESTIN--compared with those derived from UC-MSCs directly. Moreover, UC-MSC-neurospheres expressed significantly higher levels of the stemness markers NANOG, KLF4 and OCT4 than did UC-MSCs. Migration assays also revealed that both UC-MSCs and UC-MSC-neurospheres actively migrate toward glucose-depleted cells.

CONCLUSIONS

Neurogenic differentiation potential probably is greater in UC-MSC-neurospheres than in UC-MSCs. Thus, UC-MSC-neurospheres may serve as a better source of cells for neurogenic regenerative medicine.

Genetic Engineering of Mesenchymal Stem Cells to Induce Their Migration and Survival

Mesenchymal stem cells (MSCs) are very attractive for regenerative medicine due to their relatively easy derivation and broad range of differentiation capabilities, either naturally or induced through cell engineering. However, efficient methods of delivery to diseased tissues and the long-term survival of grafted cells still need improvement. Here, we review genetic engineering approaches designed to enhance the migratory capacities of MSCs, as well as extend their survival after transplantation by the modulation of prosurvival approaches, including prevention of senescence and apoptosis. We highlight some of the latest examples that explore these pivotal points, which have great relevance in cell-based therapies.

Combined mesenchymal stem cell transplantation and interleukin-1 receptor antagonism after partial hepatectomy

AIM: To study the therapeutic effects of mesenchymal stem cells (MSCs) and an interleukin-1 receptor antagonist (IL-1Ra) in acute liver failure.

METHODS: Chinese experimental miniature swine (15 ± 3 kg, 5-8 mo) were obtained from the Laboratory Animal Centre of the Affiliated Drum Tower Hospital of Nanjing University Medical School. Acute liver failure was induced via 85% hepatectomy, and animals were treated by MSC transplantation combined with IL-1Ra injection. Blood samples were collected for hepatic function analysis, and the living conditions and survival time were recorded. Liver injury was histologically analyzed. Hepatic cell regeneration and apoptosis were studied by Ki67 immunohistochemistry and terminal deoxynucleotidyl transferase dUTP nick end labeling, respectively. The levels of protein kinase B and nuclear factor-κB expression were analyzed by Western blotting.

RESULTS: MSCs were infected with a lentivirus for expression of green fluorescent protein (GFP) for subsequent identification; 97.3% of the MSCs were positive for GFP as assessed by flow cytometry. Additional flow cytometric analysis of cell surface marker expression demonstrated that > 90% of GFP-expressing MSCs were also positive for CD29, CD44, and CD90, indicating that most of these cells expressed typical markers of MSCs, and the population of MSCs was almost pure. Transplantation of MSCs in combination with 2 mg/kg IL-1Ra therapy significantly improved survival time compared to the acute liver failure model group (35.3 ± 6.7 d vs 17.3 ± 5.5 d, P < 0.05). Combined therapy also promoted improvement in serum inflammatory cytokines and biochemical conditions. The observed hepatic histopathologic score was significantly lower in the group with combined therapy than in the model group (3.50 ± 0.87 vs 8.17 ± 1.26, P < 0.01). In addition, liver cell apoptosis in the combined therapy group was significantly inhibited (18.1 ± 2.1% vs 70.8 ± 3.7%, P < 0.01), and hepatic cell regeneration increased. A significant increase in protein kinase B expression and decrease in nuclear factor-κB expression were observed (P < 0.01), which supports their important roles in liver regeneration.

CONCLUSION: MSCs and IL-1Ra had a synergistic effect in liver regeneration via regulation of inflammation and apoptotic signaling.

The Therapeutic Promise of Mesenchymal Stem Cells for Liver Restoration

Hepatocyte transplantation aims to provide a functional substitution of liver tissue lost due to trauma or toxins. Chronic liver diseases are associated with inflammation, deterioration of tissue homeostasis, and deprivation of metabolic capacity. Recent advances in liver biology have focused on the pro-regenerative features of mesenchymal stem cells (MSCs). We argue that MSCs represent an attractive therapeutic option to treat liver disease. Indeed, their pleiotropic actions include the modulation of immune reactions, the stimulation of cell proliferation, and the attenuation of cell death responses. These characteristics are highly warranted add-ons to their capacity for hepatocyte differentiation. Undoubtedly, the elucidation of the regenerative mechanisms of MSCs in different liver diseases will promote their versatile and disease-specific therapeutic use.