Human mesenchymal stem cells are recruited to injured liver in a β1-integrin and CD44 dependent manner

CD44/Integrin β1 Association Drives Fast Motility on Hyaluronic Acid Substrates

In addition to proteins such as collagen (Col) and fibronectin, the extracellular matrix (ECM) is enriched with bulky proteoglycan molecules such as hyaluronic acid (HA). However, how ECM proteins and proteoglycans collectively regulate cellular processes has not been adequately explored. Here, we address this question by studying cytoskeletal and focal adhesion organization and dynamics on cells cultured on polyacrylamide hydrogels functionalized with Col, HA and a combination of Col and HA (Col/HA). We show that fastest migration on HA substrates is attributed to the presence of smaller and weaker focal adhesions. Integrinβ $\beta $ 1 co-localization and its association with CD44-which is the receptor for HA, and insensitivity of cell spreading to RGD on HA substrates suggests that focal adhesions on HA substrates are formed via integrin association with HA bound CD44. Consistent with this, adhesion formation and cell motility were inhibited when CD44 was knocked out. Collectively, our results suggest that association of integrinβ $\beta $ 1 with CD44 drives fast motility on HA substrates.

Pharmacokinetic characteristics of mesenchymal stem cells in translational challenges

Over the past two decades, mesenchymal stem/stromal cell (MSC) therapy has made substantial strides, transitioning from experimental clinical applications to commercial products. MSC therapies hold considerable promise for treating refractory and critical conditions such as acute graft-versus-host disease, amyotrophic lateral sclerosis, and acute respiratory distress syndrome. Despite recent successes in clinical and commercial applications, MSC therapy still faces challenges when used as a commercial product. Current detection methods have limitations, leaving the dynamic biodistribution, persistence in injured tissues, and ultimate fate of MSCs in patients unclear. Clarifying the relationship between the pharmacokinetic characteristics of MSCs and their therapeutic effects is crucial for patient stratification and the formulation of precise therapeutic regimens. Moreover, the development of advanced imaging and tracking technologies is essential to address these clinical challenges. This review provides a comprehensive analysis of the kinetic properties, key regulatory molecules, different fates, and detection methods relevant to MSCs and discusses concerns in evaluating MSC druggability from the perspective of integrating pharmacokinetics and efficacy. A better understanding of these challenges could improve MSC clinical efficacy and speed up the introduction of MSC therapy products to the market.

Isolation, culture, and delivery considerations for the use of mesenchymal stem cells in potential therapies for acute liver failure

Acute liver failure (ALF) is a high-mortality syndrome for which liver transplantation is considered the only effective treatment option. A shortage of donor organs, high costs and surgical complications associated with immune rejection constrain the therapeutic effects of liver transplantation. Recently, mesenchymal stem cell (MSC) therapy was recognized as an alternative strategy for liver transplantation. Bone marrow mesenchymal stem cells (BMSCs) have been used in clinical trials of several liver diseases due to their ease of acquisition, strong proliferation ability, multipotent differentiation, homing to the lesion site, low immunogenicity and anti-inflammatory and antifibrotic effects. In this review, we comprehensively summarized the harvest and culture expansion strategies for BMSCs, the development of animal models of ALF of different aetiologies, the critical mechanisms of BMSC therapy for ALF and the challenge of clinical application.

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.

TGFβ1 priming enhances CXCR3-mediated mesenchymal stromal cell engraftment to the liver and enhances anti-inflammatory efficacy

The immunomodulatory characteristics of mesenchymal stromal cells (MSC) confers them with potential therapeutic value in the treatment of inflammatory/immune-mediated conditions. Previous studies have reported only modest beneficial effects in murine models of liver injury. In our study we explored the role of MSC priming to enhance their effectiveness. Herein we demonstrate that stimulation of human MSC with cytokine TGβ₁ enhances their homing and engraftment to human and murine hepatic sinusoidal endothelium in vivo and in vitro, which was mediated by increased expression of CXCR3. Alongside improved hepatic homing there was also greater reduction in liver inflammation and necrosis, with no adverse effects, in the CCL₄ murine model of liver injury treated with primed MSC. Priming of MSCs with TGFβ₁ is a novel strategy to improve the anti-inflammatory efficacy of MSCs.

Loss of Epidermal Homeostasis Underlies the Development of Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) is one of the most common skin cancers. To develop targeted therapies for SCC, a comprehensive understanding of the disease through a systems approach is required. Here, we have collated and analyzed the literature on SCC and pathways that maintain skin homeostasis. Since, the loss of the Notch and the overactivation of the Wnt pathways in the epidermis cause SCC, we focused on these two pathways. We found that the two pathways are critical in maintaining epidermal homeostasis. Further, we found that the cancer stem cell (CSC) marker CD44 causes the transcription of SOX2, another CSC marker of SCC, activates the Wnt pathway, and blocks the Notch pathway. Similarly, the Wnt pathway causes the transcription of CD44 and SOX2 and blocks the Notch pathway. In this paper, we have discussed how the notch and the Wnt pathways affect epidermal homeostasis and the three CSCs (CD44, SOX2, and LGR6) affect the two pathways, linking the CSCs with epidermal homeostasis.

Mesenchymal stem cells protect against ferroptosis via exosome-mediated stabilization of SLC7A11 in acute liver injury

Mesenchymal stem cells (MSCs) have attracted interest for their potential to alleviate liver injury. Here, the protective effect of MSCs on carbon tetrachloride (CCl₄)-induced acute liver injury (ALI) was investigated. In this study, we illustrated a novel mechanism that ferroptosis, a newly recognized form of regulated cell death, contributed to CCl₄-induced ALI. Subsequently, based on the in vitro and in vivo evidence that MSCs and MSC-derived exosomes (MSC-Exo) treatment achieved pathological remission and inhibited the production of lipid peroxidation, we proposed an MSC-based therapy for CCl₄-induced ALI. More intriguingly, treatment with MSCs and MSC-Exo downregulated the mRNA level of prostaglandin-endoperoxide synthase 2 (Ptgs2) and lipoxygenases (LOXs) while it restored the protein level of SLC7A11 in primary hepatocytes and mouse liver, indicating that the inhibition of ferroptosis partly accounted for the protective effect of MSCs and MSC-Exo on ALI. We further revealed that MSC-Exo-induced expression of SLC7A11 protein was accompanied by increasing of CD44 and OTUB1. The aberrant expression of ubiquitinated SLC7A11 triggered by CCl₄ could be rescued with OTUB1-mediated deubiquitination, thus strengthening SLC7A11 stability and thereby leading to the activation of system X_C⁻ to prevent CCl₄-induced hepatocyte ferroptosis. In conclusion, we showed that MSC-Exo had a protective role against ferroptosis by maintaining SLC7A11 function, thus proposing a novel therapeutic strategy for ferroptosis-induced ALI.

Schematic diagram of the protective effect of MSC-derived exosomes on maintaining SLC7A11 function during ferroptosis involved in CCl₄-induced ALI.

The epicardial delivery of cardiosphere derived cells or their extracellular vesicles is safe but of limited value in experimental infarction

The epicardial administration of therapeutics via the pericardial sac offers an attractive route, since it is minimally invasive and carries no risks of coronary embolization. The aim of this study was to assess viability, safety and effectiveness of cardiosphere-derived cells (CDCs), their extracellular vesicles (EVs) or placebo administered via a mini-thoracotomy 72 h after experimental infarction in swine. The epicardial administration was completed successfully in all cases in a surgery time (knife-to-skin) below 30 min. No significant differences between groups were found in cardiac function parameters evaluated using magnetic resonance imaging before therapy and at the end of the study, despite a trend towards improved function in CDC-treated animals. Moreover, infarct size at 10 weeks was smaller in treated animals, albeit not significantly. Arrhythmia inducibility did not differ between groups. Pathological examination showed no differences, nor were there any pericardial adhesions evidenced in any case 10 weeks after surgery. These results show that the epicardial delivery of CDCs or their EVs is safe and technically easy 3 days after experimental myocardial infarction in swine, but it does not appear to have any beneficial effect on cardiac function. Our results do not support clinical translation of these therapies as implemented in this work.

Biological, chemical and mechanical factors regulating migration and homing of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are a population of primary and non-specialized cells, which can be isolated from various tissues. Currently, MSCs are key players in cellular therapy and regenerative medicine. However, the possibility of using MSCs in the treatment of many diseases needs to be preceded, though, by in-depth analysis of their properties, especially by determining the mechanism of tissue homing as well as the mechanism, due to which cells contribute to tissue regeneration. This review is intended to present information on recent findings regarding the mechanism of recruitment and tissue homing by MSCs and discuss current hypotheses for how MSCs can reach target tissues.

Evaluation of Strategies Aimed at Improving Liver Progenitor Cell Rolling and Subsequent Adhesion to the Endothelium

Adult-derived human liver stem/progenitor cells (ADHLSCs) are a promising alternative to orthotopic liver transplantation in the treatment of inborn errors of metabolism. However, as is the case with many mesenchymal stromal cells, ADHLSCs have shown a low level of engraftment, which could be explained by the fact that they lack expression of selectin ligand and LFA-1 and only slightly express VLA- 4, molecules that have been shown to be involved in cell adhesion to the endothelium. In this paper, we have investigated strategies to increase their rolling and adhesion during the homing process by (1) adding a selectin ligand (Sialyl Lewis X) to their surface using biotinyl-N-hydroxy-succinimide–streptavidin bridges, and (2) protecting the adhesion proteins from trypsinization-induced damage using a thermosensitive polymer for cell culture and a nonenzymatic cell dissociation solution (CDS) for harvest. Despite increasing adhesion of ADHLSCs to E-selectin during an adhesion test in vitro performed under shear stress, the addition of Sialyl Lewis X did not increase adhesion to endothelial cells under the same conditions. Cultivating cells on a thermosensitive polymer and harvesting them with CDS increased their adhesion to endothelial cells under noninflammatory conditions, compared to the use of trypsin. However, we were not able to demonstrate any improvement in cell adhesion to the endothelium following culture on polymer and harvest with CDS, suggesting that alternative methods of improving engraftment still need to be evaluated.

Mesenchymal Stem Cells for Neurological Disorders

Neurological disorders are becoming a growing burden as society ages, and there is a compelling need to address this spiraling problem. Stem cell-based regenerative medicine is becoming an increasingly attractive approach to designing therapies for such disorders. The unique characteristics of mesenchymal stem cells (MSCs) make them among the most sought after cell sources. Researchers have extensively studied the modulatory properties of MSCs and their engineering, labeling, and delivery methods to the brain. The first part of this review provides an overview of studies on the application of MSCs to various neurological diseases, including stroke, traumatic brain injury, spinal cord injury, multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease, Parkinson's disease, and other less frequently studied clinical entities. In the second part, stem cell delivery to the brain is focused. This fundamental but still understudied problem needs to be overcome to apply stem cells to brain diseases successfully. Here the value of cell engineering is also emphasized to facilitate MSC diapedesis, migration, and homing to brain areas affected by the disease to implement precision medicine paradigms into stem cell-based therapies.

Therapeutic Use of Mesenchymal Stromal Cells: The Need for Inclusive Characterization Guidelines to Accommodate All Tissue Sources and Species

Following their discovery over 50 years ago, mesenchymal stromal cells (MSCs) have become one of the most studied cellular therapeutic products by both academia and industry due to their regenerative potential and immunomodulatory properties. The promise of MSCs as a therapeutic modality has been demonstrated by preclinical data yet has not translated to consistent, successful clinical trial results in humans. Despite the disparities across the field, MSC shareholders are unified under one common goal-to use MSCs as a therapeutic modality to improve the quality of life for those suffering from a malady in which the standard of care is suboptimal or no longer effective. Currently, there is no Food and Drug Administration (FDA)-approved MSC therapy on the market in the United States although several MSC products have been granted regulatory approval in other countries. In this review, we intend to identify hurdles that are impeding therapeutic progress and discuss strategies that may aid in accomplishing this universal goal of widespread therapeutic use.

Mesenchymal Stromal Cells, a New Player in Reducing Complications From Liver Transplantation?

In response to the global burden of liver disease there has been a commensurate increase in the demand for liver transplantation. However, due to a paucity of donor organs many centers have moved toward the routine use of marginal allografts, which can be associated with a greater risk of complications and poorer clinical outcomes. Mesenchymal stromal cells (MSC) are a multi-potent progenitor cell population that have been utilized to modulate aberrant immune responses in acute and chronic inflammatory conditions. MSC exert an immunomodulatory effect on innate and adaptive immune systems through the release of both paracrine soluble factors and extracellular vesicles. Through these routes MSC can switch the regulatory function of the immune system through effects on macrophages and T regulatory cells enabling a switch of phenotype from injury to restoration. A key benefit seems to be their ability to tailor their response to the inflammatory environment without compromising the host ability to fight infection. With over 200 clinical trials registered to examine MSC therapy in liver disease and an increasing number of trials of MSC therapy in solid organ transplant recipients, there is increasing consideration for their use in liver transplantation. In this review we critically appraise the potential role of MSC therapy in the context of liver transplantation, including their ability to modulate reperfusion injury, their role in the reduction of medium term complications in the biliary tree and their potential to enhance tolerance in transplanted organs.

Dynamic Regulation of miRNA Expression by Functionally Enhanced Placental Mesenchymal Stem Cells PromotesHepatic Regeneration in a Rat Model with Bile Duct Ligation

Placenta-derived mesenchymal stem cells (PD-MSCs) were highlighted as therapeutic sources in several degenerative diseases. Recently, microRNAs (miRNAs)were found to mediate one of the therapeutic mechanisms of PD-MSCs in regenerative medicine. To enhance the therapeutic effects of PD-MSCs, we established functionally enhanced PD-MSCs with phosphatase of regenerating liver-1 overexpression (PRL-1(+)). However, the profile and functions of miRNAs induced by PRL-1(+) PD-MSCs in a rat model with hepatic failure prepared by bile duct ligation (BDL) remained unclear. Hence, the objectives of the present study were to analyze the expression of miRNAs and investigate their therapeutic mechanisms for hepatic regeneration via PRL-1(+) in a rat model with BDL. We selected candidate miRNAs based on microarray analysis. Under hypoxic conditions, compared with migrated naïve PD-MSCs, migrated PRL-1(+) PD-MSCs showed improved integrin-dependent migration abilitythrough Ras homolog (RHO) family-targeted miRNA expression (e.g., hsa-miR-30a-5p, 340-5p, and 146a-3p). Moreover, rno-miR-30a-5p and 340-5p regulated engraftment into injured rat liver by transplantedPRL-1(+) PD-MSCs through the integrin family. Additionally, an increase inplatelet-derived growth factor receptor A (PDGFRA) by suppressing rno-miR-27a-3p improved vascular structure in rat liver tissues after PRL-1(+) PD-MSC transplantation. Furthermore, decreased rno-miR-122-5p was significantly correlated with increased proliferation of hepatocytes in liver tissues by PRL-1(+) PD-MSCs byactivating the interleukin-6 (IL-6) signaling pathway through the repression of rno-miR-21-5p. Taken together, these findings improve the understandingof therapeutic mechanisms based on miRNA-mediated stem-cell therapy in liver diseases.

Mesenchymal Stem Cells in the Adult Human Liver: Hype or Hope?

Chronic liver diseases constitute a significant economic, social, and biomedical burden. Among commonly adopted approaches, only organ transplantation can radically help patients with end-stage liver pathologies. Cell therapy with hepatocytes as a treatment for chronic liver disease has demonstrated promising results. However, quality human hepatocytes are in short supply. Stem/progenitor cells capable of differentiating into functionally active hepatocytes provide an attractive alternative approach to cell therapy for liver diseases, as well as to liver-tissue engineering, drug screening, and basic research. The application of methods generally used to isolate mesenchymal stem cells (MSCs) and maintain them in culture to human liver tissue provides cells, designated here as liver MSCs. They have much in common with MSCs from other tissues, but differ in two aspects-expression of a range of hepatocyte-specific genes and, possibly, inherent commitment to hepatogenic differentiation. The aim of this review is to analyze data regarding liver MSCs, probably another type of liver stem/progenitor cells different from hepatic stellate cells or so-called hepatic progenitor cells. The review presents an analysis of the phenotypic characteristics of liver MSCs, their differentiation and therapeutic potential, methods for isolating these cells from human liver, and discusses issues of their origin and heterogeneity. Human liver MSCs are a fascinating object of fundamental research with a potential for important practical applications.

Biological functions of mesenchymal stem cells and clinical implications

Mesenchymal stem cells (MSCs) are isolated from multiple biological tissues-adult bone marrow and adipose tissues and neonatal tissues such as umbilical cord and placenta. In vitro, MSCs show biological features of extensive proliferation ability and multipotency. Moreover, MSCs have trophic, homing/migration and immunosuppression functions that have been demonstrated both in vitro and in vivo. A number of clinical trials are using MSCs for therapeutic interventions in severe degenerative and/or inflammatory diseases, including Crohn's disease and graft-versus-host disease, alone or in combination with other drugs. MSCs are promising for therapeutic applications given the ease in obtaining them, their genetic stability, their poor immunogenicity and their curative properties for tissue repair and immunomodulation. The success of MSC therapy in degenerative and/or inflammatory diseases might depend on the robustness of the biological functions of MSCs, which should be linked to their therapeutic potency. Here, we outline the fundamental and advanced concepts of MSC biological features and underline the biological functions of MSCs in their basic and translational aspects in therapy for degenerative and/or inflammatory diseases.

Bone Marrow-Derived CD44+ Cells Migrate to Tissue-Engineered Constructs via SDF-1/CXCR4-JNK Pathway and Aid Bone Repair

Background and Aims

Host-derived cells play crucial roles in the regeneration process of tissue-engineered constructs (TECs) during the treatment of large segmental bone defects (LSBDs). However, their identity, source, and cell recruitment mechanisms remain elusive.

Methods

A complex model was created using mice by combining methods of GFP⁺ bone marrow transplantation (GFP-BMT), parabiosis (GFP⁺-BMT and wild-type mice), and femoral LSBD, followed by implantation of TECs or DBM scaffolds. Postoperatively, the migration of host BM cells was detected by animal imaging and immunofluorescent staining. Bone repair was evaluated by micro-CT. Signaling pathway repressors including AMD3100 and SP600125 associated with the migration of BM CD44⁺ cells were further investigated. In vitro, transwell migration and western-blotting assays were performed to verify the related signaling pathway. In vivo, the importance of the SDF-1/CXCR4-JNK pathway was validated by ELISA, fluorescence-activated cell sorting (FACS), immunofluorescent staining, and RT-PCR.

Results

First, we found that host cells recruited to facilitate TEC-mediated bone repair were derived from bone marrow and most of them express CD44, indicating the significance of CD44 in the migration of bone marrow cells towards donor MSCs. Then, the predominant roles of SDF-1/CXCR4 and downstream JNK in the migration of BM CD44⁺ cells towards TECs were demonstrated.

Conclusion

Together, we demonstrated that during bone repair promoted by TECs, BM-derived CD44⁺ cells were essential and their migration towards TECs could be regulated by the SDF-1/CXCR4-JNK signaling pathway.

The role of stem cells in liver injury and repair

Introduction: Liver disease is an increasing cause of worldwide mortality, and currently the only curative treatment for end-stage liver disease is whole organ allograft transplantation. Whilst this is an effective treatment, there is a shortage of suitable grafts and consequently some patients die whilst on the waiting list. Cell therapy provides an alternative treatment to increase liver function and potentially ameliorate fibrosis. Areas covered: In this review, we discuss the different cellular sources for therapy investigated to date in humans including mature hepatocytes, hematopoietic stem cells, mesenchymal stromal cells and hepatic progenitor cells. Cells investigated in animals include embryonic stem cells, induced pluripotent stem cells and directly reprogrammed cells. We then appraise the experience and evidence base underlying each cell type. Expert opinion: We discuss how this field may evolve in the years to come focusing on opportunities to enhance the intrinsic regenerative response with therapeutic targets and cell therapies. Growing expertise in tissue engineering will likely lead to increasingly complex bio-reactors and bio-artificial livers, which open a further avenue to restore liver function and delay or prevent the need for transplantation.

Mesenchymal stem cell-based drug delivery strategy: from cells to biomimetic

Owing to the diversity and ease of preparation of nanomaterials, the rational nanocarriers with a rational design have become increasingly popular in medical researches. Although nanoparticle-based drug delivery exhibits great potential, there are some challenges facing like rapid plasma clearance, triggering or aggravation of immune response, etc. Herein, cell-based targeted drug delivery systems have drawn more and more attention owing to low immunogenicity and intrinsic mutation rate, and innate ability to allow targeted delivery. Mesenchymal stem cells (MSCs) have been used in gene and drug delivery. The use of MSCs is a promising approach for the development of gene transfer systems and drug loading strategies because of their intrinsic properties, including homing ability and tumor tropism. By combining the inherent cell properties and merits of synthetic nanoparticles (NPs), cell membrane coated NPs emerge as the time requires. Overall, we provide a comprehensive overview of the utility of MSCs in drug and gene delivery as well as MSC membrane coated nanoparticles for therapy and drug delivery, aiming to figure out the significant room for development and highlight the potential future directions.

Microgravity-induced hepatogenic differentiation of rBMSCs on board the SJ-10 satellite

Bone marrow-derived mesenchymal stem cells (BMSCs) are able to differentiate into functional hepatocytelike cells, which are expected to serve as a potential cell source in regenerative medicine, tissue engineering, and clinical treatment of liver injury. Little is known about whether and how space microgravity is able to direct the hepatogenic differentiation of BMSCs in the actual space microenvironment. In this study, we examined the effects of space microgravity on BMSC hepatogenic differentiation on board the SJ-10 Recoverable Scientific Satellite. Rat BMSCs were cultured and induced in hepatogenic induction medium for 3 and 10 d in custom-made space cell culture hardware. Cell growth was monitored periodically in orbit, and the fixed cells and collected supernatants were retrieved back to the Earth for further analyses. Data indicated that space microgravity improves the differentiating capability of the cells by up-regulating hepatocyte-specific albumin and cytokeratin 18. The resulting cells tended to be maturated, with an in-orbit period of up to 10 d. In space, mechanosensitive molecules of β1-integrin, β-actin, α-tubulin, and Ras homolog gene family member A presented enhanced expression, whereas those of cell-surface glycoprotein CD44, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, vinculin, cell division control protein 42 homolog, and Rho-associated coiled-coil kinase yielded reduced expression. Also observed in space were the depolymerization of actin filaments and the accumulation of microtubules and vimentin through the altered expression and location of focal adhesion complexes, Rho guanosine 5'-triphosphatases, as well as the enhanced exosome-mediated mRNA transfer. This work furthers the understanding of the underlying mechanisms of space microgravity in directing hepatogenic differentiation of BMSCs.-Lü, D., Sun, S., Zhang, F., Luo, C., Zheng, L., Wu, Y., Li, N., Zhang, C., Wang, C., Chen, Q., Long, M. Microgravity-induced hepatogenic differentiation of rBMSCs on board the SJ-10 satellite.

Mesenchymal Stem Cell Functionalization for Enhanced Therapeutic Applications

IMPACT STATEMENT

Culture expansion of MSCs has detrimental effects on various cell characteristics and attributes (e.g., phenotypic changes and senescence), which, in addition to inherent interdonor variability, negatively impact the standardization and reproducibility of their therapeutic potential. The identification of innate distinct functional MSC subpopulations, as well as the description of ex vivo protocols aimed at maintaining phenotypes and enhancing specific functions have the potential to overcome these limitations. The incorporation of those approaches into cell-based therapy would significantly impact the field, as more reproducible clinical outcomes may be achieved.

Ameliorating effect of encapsulated hepatocyte-like cells derived from umbilical cord in high mannuronic alginate scaffolds on acute liver failure in rats

OBJECTIVES

In this study, effects of encapsulated umbilical cord stem cells (UCSCs)-derived hepatocyte-like cells (HLCs) in high mannuronic alginate scaffolds was investigated on CCl4-induced acute liver failure (ALF) in rats.

MATERIAL AND METHODS

UCSCs were encapsulated in high mannuronic alginate scaffolds. Then the UCSCs differentiated into HLCs for treatment of CCl4-induced ALF in rats. Thirty rats randomly divided into 5 groups: Intoxicated group received only CCl4 to induce ALF. In other groups including cell-free, UCSCs and HLCs, alginate scaffolds were transplanted into the liver 4 days after CCl4 injection. Biochemical markers including albumin (ALB), blood urea nitrogen (BUN), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were evaluated. Histological changes and gene expression of ALB, alpha-fetoprotein (AFP), and cytokeratin 18 (CK-18) were also assessed.

RESULTS

Expression of CK-18 significantly increased in HLCs compared to the UCSCs in vitro. This indicates that UCSCs can effectively differentiate into the HLCs. In CCl4-intoxicated group, BUN, AST and ALT levels, and histological criteria, such as infiltration of inflammatory cells, accumulation of reticulocytes, nuclear pyknosis of hepatocyte and sinusoidal dilation, significantly increased. In this group, ALB secretion significantly decreased, while AFP expression significantly increased. Both UCSCs and HLCs encapsulated in alginate scaffolds effectively attenuated biochemical tests, improved liver cytoarchitecture, increased expression of ALB and reduced AFP expression.

CONCLUSION

Finding of the present study indicated that encapsulation of UCSCs or HLCs in alginate mannuronic scaffolds effectively improve CCl4-induced ALF.

Bioengineered cellular and cell membrane-derived vehicles for actively targeted drug delivery: So near and yet so far

Cellular carriers for drug delivery are attractive alternatives to synthetic nanoparticles owing to their innate homing/targeting abilities. Here, we review molecular interactions involved in the homing of Mesenchymal stem cells (MSCs) and other cell types to understand the process of designing and engineering highly efficient, actively targeting cellular vehicles. In addition, we comprehensively discuss various genetic and non-genetic strategies and propose futuristic approaches of engineering MSC homing using micro/nanotechnology and high throughput small molecule screening. Most of the targeting abilities of a cell come from its plasma membrane, thus, efforts to harness cell membranes as drug delivery vehicles are gaining importance and are highlighted here. We also recognize and report the lack of detailed characterization of cell membranes in terms of safety, structural integrity, targeting functionality, and drug transport. Finally, we provide insights on future development of bioengineered cellular and cell membrane-derived vesicles for successful clinical translation.

Origin-Specific Adhesive Interactions of Mesenchymal Stem Cells with Platelets Influence Their Behavior After Infusion

We investigated the adhesive behavior of mesenchymal stem cells (MSC) in blood, which might influence their fate when infused as therapy. Isolated human bone marrow MSC (BMMSC) or umbilical cord MSC (UCMSC) adhered efficiently from flow to the matrix proteins, collagen, or fibronectin, but did not adhere to endothelial selectins. However, when suspended in blood, BMMSC no longer adhered to collagen, while UCMSC adhered along with many aggregated platelets. Neither MSC adhered to fibronectin from flowing blood, although the fibronectin surface did become coated with a platelet monolayer. UCMSC induced platelet aggregation in platelet rich plasma, and caused a marked drop in platelet count when mixed with whole human or mouse blood in vitro, or when infused into mice. In contrast, BMMSC did not activate platelets or induce changes in platelet count. Interestingly, isolated UCMSC and BMMSC both adhered to predeposited platelets. The differences in behavior in blood were attributable to expression of podoplanin (an activating ligand for the platelet receptor CLEC‐2), which was detected on UCMSC, but not BMMSC. Thus, platelets were activated when bound to UCMSC, but not BMMSC. Platelet aggregation by UCMSC was inhibited by recombinant soluble CLEC‐2, and UCMSC did not cause a reduction in platelet count when mixed with blood from mice deficient in CLEC‐2. We predict that both MSC would carry platelets in the blood, but their interaction with vascular endothelium would depend on podoplanin‐induced activation of the bound platelets. Such interactions with platelets might target MSC to damaged tissue, but could also be thrombotic. Stem Cells2018;36:1062–1074

Mesenchymal stem cell therapy for advanced liver cirrhosis: A case report

Mesenchymal stem cell (MSC) transplant may offer an alternative to liver transplantation in patients with end‐stage liver disease. However, its efficacy remains uncertain. MSC was performed on a 50‐year‐old male with decompensated (Child‐Turcotte‐Pugh grade C) alcoholic liver cirrhosis due to an absence of donors for adult‐deceased and living‐related liver transplantation. Autologous bone marrow‐derived MSCs were harvested from the patient and cultured using standard protocols. The MSCs were subsequently re‐administrated into the liver via hepatic intra‐arterial infusion on two separate occasions. After infusion, there was an improvement in biochemical parameters (serum total bilirubin, serum albumin), and a reduction of diuretic use for ascites for up to 8 weeks. However, all biochemical and clinical parameters deteriorated on long‐term follow‐up without any further infusions. The patient eventually succumbed to his disease. MSC transplantation may have a clinical benefit on adult patients with end‐stage liver cirrhosis, but this appears to be transitory.

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.

Comprehensive Screening of Cell Surface Markers Expressed by Adult-Derived Human Liver Stem/Progenitor Cells Harvested at Passage 5: Potential Implications for Engraftment

Mesenchymal stromal cells (MSCs) are known to have potential therapeutic benefits for a number of diseases. However, many studies report low engraftment levels, regardless of the target organ. One possible explanation could be that MSCs do not express the necessary receptors for engraftment. Indeed, MSCs appear to use a similar mechanism to leukocytes to engraft into injured organs, relying on various receptors for rolling, firm adhesion, and transmigration. In this study, we conducted an extensive surface molecule screening of adult-derived human liver stem/progenitor cells (ADHLSC) in an attempt to shed some light on this subject. We observed that ADHLSCs lack expression of most of the costimulatory molecules tested. Furthermore, study of the adhesion molecule profile of ADHLSCs revealed that they do not express selectin ligands or LFA-1 which are, respectively, involved in the rolling process and the firm adhesion. In addition, ADHLSCs slightly express VLA-4 and lose expression of CXCR4 altogether on their surface during culture expansion. However, ADHLSCs express all the integrin couples and matrix metalloproteinases needed to bind and integrate the extracellular matrix once the endothelial barrier is crossed. Collectively, these results suggest that binding to the endothelium may be the critical weak point in the engraftment process.

Human endometrial regenerative cells alleviate carbon tetrachloride-induced acute liver injury in mice

Background

The endometrial regenerative cell (ERC) is a novel type of adult mesenchymal stem cell isolated from menstrual blood. Previous studies demonstrated that ERCs possess unique immunoregulatory properties in vitro and in vivo, as well as the ability to differentiate into functional hepatocyte-like cells. For these reasons, the present study was undertaken to explore the effects of ERCs on carbon tetrachloride (CCl₄)–induced acute liver injury (ALI).

Methods

An ALI model in C57BL/6 mice was induced by administration of intraperitoneal injection of CCl₄. Transplanted ERCs were intravenously injected (1 million/mouse) into mice 30 min after ALI induction. Liver function, pathological and immunohistological changes, cell tracking, immune cell populations and cytokine profiles were assessed 24 h after the CCl₄ induction.

Results

ERC treatment effectively decreased the CCl₄-induced elevation of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and improved hepatic histopathological abnormalities compared to the untreated ALI group. Immunohistochemical staining showed that over-expression of lymphocyte antigen 6 complex, locus G (Ly6G) was markedly inhibited, whereas expression of proliferating cell nuclear antigen (PCNA) was increased after ERC treatment. Furthermore, the frequency of CD4⁺ and CD8⁺ T cell populations in the spleen was significantly down-regulated, while the percentage of splenic CD4⁺CD25⁺FOXP3⁺ regulatory T cells (Tregs) was obviously up-regulated after ERC treatment. Moreover, splenic dendritic cells in ERC-treated mice exhibited dramatically decreased MHC-II expression. Cell tracking studies showed that transplanted PKH26-labeled ERCs engrafted to lung, spleen and injured liver. Compared to untreated controls, mice treated with ERCs had lower levels of IL-1β, IL-6, and TNF-α but higher level of IL-10 in both serum and liver.

Conclusions

Human ERCs protect the liver from acute injury in mice through hepatocyte proliferation promotion, as well as through anti-inflammatory and immunoregulatory effects.

Adhesion of mesenchymal stem cells to biomimetic polymers: A review

The mesenchymal stem cells (MSCs) are promising candidates for cell therapy due to the self-renewal, multi-potency, ethically approved state and suitability for autologous transplantation. However, key issue for isolation and manipulation of MSCs is adhesion in ex-vivo culture systems. Biomaterials engineered for mimicking natural extracellular matrix (ECM) conditions which support stem cell adhesion, proliferation and differentiation represent a main area of research in tissue engineering. Some of them successfully enhanced cells adhesion and proliferation because of their biocompatibility, biomimetic texture, and chemistry. However, it is still in its infancy, therefore intensification and optimization of in vitro, in vivo, and preclinical studies is needed to clarify efficacies as well as applicability of those bioengineered constructs. The aim of this review is to discuss mechanisms related to the in-vitro adhesion of MSCs, surfaces biochemical, biophysical, and other factors (of cell's natural and artificial micro-environment) which could affect it and a review of previous research attempting for its bio-chemo-optimization.

Liver regeneration - mechanisms and models to clinical application

Liver regeneration has been studied for many decades and the mechanisms underlying regeneration of the normal liver following resection or moderate damage are well described. A large number of factors extrinsic (such as bile acids and circulating growth factors) and intrinsic to the liver interact to initiate and regulate liver regeneration. Less well understood, and more clinically relevant, are the factors at play when the abnormal liver is required to regenerate. Fatty liver disease, chronic scarring, prior chemotherapy and massive liver injury can all inhibit the normal programme of regeneration and can lead to liver failure. Understanding these mechanisms could enable the rational targeting of specific therapies to either reduce the factors inhibiting regeneration or directly stimulate liver regeneration. Although animal models of liver regeneration have been highly instructive, the clinical relevance of some models could be improved to bridge the gap between our in vivo model systems and the clinical situation. Likewise, modern imaging techniques such as spectroscopy will probably improve our understanding of whole-organ metabolism and how this predicts the liver's regenerative capacity. This Review describes briefly the mechanisms underpinning liver regeneration, the models used to study this process, and discusses areas in which failed or compromised liver regeneration is clinically relevant.

Extrinsic and Intrinsic Mechanisms by Which Mesenchymal Stem Cells Suppress the Immune System

Mesenchymal stem cells (MSCs) are a group of fibroblast-like multipotent mesenchymal stromal cells that have the ability to differentiate into osteoblasts, adipocytes, and chondrocytes. Recent studies have demonstrated that MSCs possess a unique ability to exert suppressive and regulatory effects on both adaptive and innate immunity in an autologous and allogeneic manner. A vital step in stem cell transplantation is overcoming the potential graft-versus-host disease, which is a limiting factor to transplantation success. Given that MSCs attain powerful differentiation capabilities and also present immunosuppressive properties, which enable them to survive host immune rejection, MSCs are of great interest. Due to their ability to differentiate into different cell types and to suppress and modulate the immune system, MSCs are being developed for treating a plethora of diseases, including immune disorders. Moreover, in recent years, MSCs have been genetically engineered to treat and sometimes even cure some diseases, and the use of MSCs for cell therapy presents new perspectives for overcoming tissue rejection. In this review, we discuss the potential extrinsic and intrinsic mechanisms that underlie MSCs' unique ability to modulate inflammation, and both innate and adaptive immunity.

Mesenchymal stromal cell therapy in liver disease: opportunities and lessons to be learnt?

End-stage liver disease is responsible for 30,000 deaths per year in the United States alone, and it is continuing to increase every year. With liver transplantation the only curative treatment currently available, new therapies are in great demand. Mesenchymal stem cells (MSC) offer an opportunity to both treat liver inflammatory damage, as well as reverse some of the changes that occur following chronic liver injury. With the ability to regulate both the innate and adaptive immune system, as well as both inhibit and promote apoptosis of effector inflammatory cells, there are numerous therapeutic opportunities for MSC in acute and chronic liver disease. This article critically appraises the potential therapeutic roles of MSC in liver disease, as well as the barriers to their adoption into clinical practice.

Microenvironmental Interaction Between Hypoxia and Endothelial Cells Controls the Migration Ability of Placenta-Derived Mesenchymal Stem Cells via α4 Integrin and Rho Signaling

Mesenchymal stem cells (MSCs) are a powerful source for cell therapy in degenerative diseases. The migration ability of MSCs is an important factor that enhances the therapeutic effect of the cells when they are transplanted into target tissues or organs. Hypoxia and the endothelial barrier, which are representative migration microenvironmental factors, are known to be regulated by the integrin-mediated pathway in several cancers. However, their regulatory mechanisms in MSCs remain unclear. Here, the objectives of the study were to compare the expression of markers related to integrin-mediated signaling in placenta-derived MSCs (PDMSCs) dependent on hypoxia and co-cultured with human umbilical vein endothelial cells (HUVECs) and to evaluate their correlations between migration ability and microenvironmetal factors including hypoxia and endothelial cells. The migration abilities of PDMSCs exposed to hypoxic conditions were significantly increased compared with normal fibroblasts (WI-38) and control (P < 0.05). Interestingly, decreased integrin α4 in PDMSCs under hypoxia induce to increase migration abilities of PDMSCs. Also, Rho family-related markers were significantly increased in PDMSCs under hypoxic conditions compared with normoxia (P < 0.05). Furthermore, the migration ability of PDMSCs was decreased by Rho kinase inhibitor treatment (Y-27632) and co-culturing with HUVECs in an ex vivo system. ROCK activity was increased by inhibiting integrin α4 with HUVECs and hypoxia compared with the absence of HUVECs and under normoxia. The findings suggest microenvironment event by hypoxia and the interaction with endothelial cells may be useful as a regulator of MSC migration and provide insight into the migratory mechanism of MSCs in stem cell-based therapy.

Association between in vivo bone formation and ex vivo migratory capacity of human bone marrow stromal cells

Introduction

There is a clinical need for developing systemic transplantation protocols for use of human skeletal stem cells (also known bone marrow stromal stem cells) (hBMSC) in tissue regeneration. In systemic transplantation studies, only a limited number of hBMSC home to injured tissues suggesting that only a subpopulation of hBMSC possesses “homing” capacity. Thus, we tested the hypothesis that a subpopulation of hBMSC defined by ability to form heterotopic bone in vivo, is capable of homing to injured bone.

Methods

We tested ex vivo and in vivo homing capacity of a number of clonal cell populations derived from telomerized hBMSC (hBMSC-TERT) with variable ability to form heterotopic bone when implanted subcutaneously in immune deficient mice. In vitro transwell migration assay was used and the in vivo homing ability of transplanted hBMSC to bone fractures in mice was visualized by bioluminescence imaging (BLI). In order to identify the molecular phenotype associated with enhanced migration, we carried out comparative DNA microarray analysis of gene expression of hBMSC-derived high bone forming (HBF) clones versus low bone forming (LBF) clones.

Results

HBF clones were exhibited higher ex vivo transwell migration and following intravenous injection, better in vivo homing ability to bone fracture when compared to LBF clones. Comparative microarray analysis of HBF versus LBF clones identified enrichment of gene categories of chemo-attraction, adhesion and migration associated genes. Among these, platelet-derived growth factor receptor (PDGFR) α and β were highly expressed in HBF clones. Follow up studies showed that the chemoattractant effects of PDGF in vitro was more enhanced in HBF compared to LBF clones and this effect was reduced in presence of a PDGFRβ-specific inhibitor: SU-16 f. Also, PDGF exerted greater chemoattractant effect on PDGFRβ⁺ cells sorted from LBF clones compared to PDGFRβ^- cells.

Conclusion

Our data demonstrate phenotypic and molecular association between in vivo bone forming ability and migratory capacity of hBMSC. PDGFRβ can be used as a potential marker for the prospective selection of hBMSC populations with high migration and bone formation capacities suitable for clinical trials for enhancing bone regeneration.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0188-9) contains supplementary material, which is available to authorized users.

Pretreatment of Mesenchymal Stem Cells Manipulates Their Vasculoprotective Potential While Not Altering Their Homing Within the Injured Gut

Mesenchymal stem cells (MSCs) have shown therapeutic promise in many experimental and clinical models of inflammation. However, a commonly reported feature of MSC transplantation is poor homing to injured tissues. Previously, we have shown that pretreatment with cytokines/chemical factors enhances hematopoietic SC adhesion within intestinal microvasculature following ischemia-reperfusion (IR) injury. Using intravital microscopy, the ability of similar pretreatment strategies to enhance the recruitment of murine MSCs to murine intestinal microvasculature following IR injury was investigated. Primary MSCs were isolated from bone marrow and selected on the basis of platelet-derived growth factor receptor-α and SC antigen-1 positivity (PDGFRα(+) /Sca-1(+) ). MSC recruitment was similar in IR injured gut mucosa when compared with sham operated controls, with limited cell adhesion observed. MSCs appeared contorted in microvessels, suggesting physical entrapment. Although not recruited specifically by injury, MSC administration significantly reduced neutrophil recruitment and improved tissue perfusion in the severely injured jejunum. Vasculoprotective effects were not demonstrated in the lesser injured ileum. Pretreatment of MSCs with tumor necrosis factor (TNF)-α, CXCL12, interferon (IFN)-γ, or hydrogen peroxide did not enhance their intestinal recruitment. In fact, TNFα and IFNγ removed the previous therapeutic ability of transplanted MSCs to reduce neutrophil infiltration and improve perfusion in the jejunum. We provide direct evidence that MSCs can rapidly limit leukocyte recruitment and improve tissue perfusion following intestinal IR injury. However, this study also highlights complexities associated with strategies to improve MSC therapeutic efficacy. Future studies using cytokine/chemical pretreatments to enhance MSC recruitment/function require careful consideration and validation to ensure therapeutic function is not impeded.

Crosstalk between mesenchymal stem cells and endothelial cells leads to downregulation of cytokine-induced leukocyte recruitment

Mesenchymal stem cells (MSC) have immunomodulatory properties, but their effects on endothelial cells (EC) and recruitment of leukocytes are unknown. We cocultured human bone marrow-derived MSC with EC and found that MSC could downregulate adhesion of flowing neutrophils or lymphocytes and their subsequent transendothelial migration. This applied for EC treated with tumor necrosis factor-α (TNF), interleukin-1β (IL-1), or TNF and interferon-γ combined. Supernatant from cocultures also inhibited endothelial responses. This supernatant had much higher levels of IL-6 than supernatant from cultures of the individual cells, which also lacked inhibitory functions. Addition of neutralizing antibody against IL-6 removed the bioactivity of the supernatant and also the immunomodulatory effects of coculture. Studies using siRNA showed that IL-6 came mainly from the MSC in coculture, and reduction in production in MSC alone was sufficient to impair the protective effects of coculture. Interestingly, siRNA knockdown of IL-6-receptor expression in MSC as well as EC inhibited anti-inflammatory effects. This was explained when we detected soluble IL-6R receptor in supernatants and showed that receptor removal reduced the potency of supernatant. Neutralization of transforming growth factor-β indicated that activation of this factor in coculture contributed to IL-6 production. Thus, crosstalk between MSC and EC caused upregulation of production of IL-6 by MSC which in turn downregulated the response of EC to inflammatory cytokines, an effect potentiated by MSC release of soluble IL-6R. These studies establish a novel mechanism by which MSC might have protective effects against inflammatory pathology and cardiovascular disease.

Migration mechanism of mesenchymal stem cells studied by QD/NSOM

The migration of mesenchymal stem cells (MSCs) plays a key role in tumor-targeted delivery vehicles and tumor-related stroma formation. However, there so far has been no report on the distribution of cell surface molecules during the VEGF-induced migration of MSCs. Here, we have utilized near-field scanning optical microscopy (NSOM) combined with fluorescent quantum dot (QD)-based nano-technology to capture the functional relationship between CD44 and CD29 adhesion molecules on MSCs and the effect of their spatial rearrangements. Before VEGF-induced migration of MSCs, both CD44 and CD29 formed 200-220 nm nano-domains respectively, with little co-localization between the two types of domains. Surprisingly, the size of the CD44 nano-domain rapidly increased in size to 295 nm and apparently larger aggregates were formed following MSC treatment with VEGF for 10 min, while the area of co-localization increased to 0.327 μm2. Compared with CD44, CD29 was activated obviously later, for the fact that CD29 aggregation didn't appear until 30 min after VEGF treatment. Consistently, its co-localization area increased to 0.917 μm2. The CD44 and CD29 nano-domains further aggregated into larger nano-domains or even formed micro-domains on the membrane of activated MSCs. The aggregation and co-localization of these molecules promoted FAK formation and cytoskeleton rearrangement. All of the above changes induced by VEGF contributed to MSC migration. Taken together, our data of NSOM-based dual color fluorescent imaging demonstrated for the first time that CD44, together with CD29, involved in VEGF-induced migration of MSCs through the interaction between CD44 and its co-receptor of VEGFR-2.

Non-enzymatic dissociation of human mesenchymal stromal cells improves chemokine-dependent migration and maintains immunosuppressive function

BACKGROUND AIMS

Human bone marrow-derived mesenchymal stromal cells (MSC) can suppress inflammation; therefore their therapeutic potential is being explored in clinical trials. Poor engraftment of infused MSC limits their therapeutic utility; this may be caused by MSC processing before infusion, in particular the method of their detachment from culture.

METHODS

Enzymatic methods of detaching MSC (Accutase and TrypLE) were compared with non-enzymatic methods (Cell Dissociation Buffer [CDB], ethylenediamine tetra-acetic acid and scraping) for their effect on MSC viability, chemokine receptor expression, multi-potency, immunomodulation and chemokine-dependent migration.

RESULTS

TrypLE detachment preserved MSC viability and tri-lineage potential compared with non-enzymatic methods; however, this resulted in near complete loss of surface chemokine receptor expression. Of the non-enzymatic methods, CDB detachment preserved the highest viability while retaining significant tri-lineage differentiation potential. Once re-plated, CDB-detached MSC regained their original morphology and reached confluence, unlike with the use of other non-enzymatic methods. Viability was significantly reduced with the use of ethylenediamine tetra-acetic acid and further reduced with the use of cell scraping. Addition of 1% serum during CDB detachment led to higher MSC numbers entering autophagy and increased MSC recovery after re-plating. TrypLE and CDB-detached MSC suppressed CD3(+)CD4(+)CD25(-) T-cell proliferation, although TrypLE-detached MSC exhibited superior suppression at 1:20 ratio. CDB detachment retained surface chemokine receptor expression and consequently increased migration to CCL22, CXCL12 and CCL4, in contrast with TrypLE-detached MSC.

CONCLUSIONS

This study demonstrates that non-enzymatic detachment of MSC with the use of CDB minimizes the negative impact on cell viability, multipotency and immunomodulation while retaining chemokine-dependent migration, which may be of importance in MSC delivery and engraftment in sites of injury.

Advances in mesenchymal stem cells combined with traditional Chinese medicine therapy for liver fibrosis

Liver fibrosis is a primary cause of liver cirrhosis, and even hepatocarcinoma. Recently, the usage of mesenchymal stem cells (MSCs) has been investigated to improve liver fibrosis. It has been reported that the differentiation, proliferation and migration of MSCs can be regulated by traditional Chinese medicine treatment; however, the mechanisms are still unclear. In this article, the authors review the characteristics of MSCs such as multidirectional differentiation and homing, and its application in animal experiments and clinical trials. The authors also list areas that need further investigation, andlook at the future prospects of clinical application of MSCs.

RETRACTED: Human bone marrow, umbilical cord or liver mesenchymal stromal cells fail to improve liver function in a model of CCl4-induced liver damage in NOD/SCID/IL-2Rγ(null) mice

This article has been removed: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been removed at the request of the Editor in Chief. This retraction comes after a thorough investigation of the scientific research presented in the article, along with an investigation into the authorship of the article and the ownership of the data presented. The Editor in Chief's decision to retract the article is based upon the authors' misuse and misrepresentation of a peer's scientific data without consent or approval.

Adipose derived mesenchymal stem cells efficiently rescue carbon tetrachloride-induced acute liver failure in mouse

Background and Aim. Adipose derived mesenchymal stem cells (ADMSCs) may be an attractive source for acute and chronic liver injury because they are abundant and easy to obtain. We aim to investigate the efficacy of ADMSCs transplantation in the acute liver failure (ALF) caused by carbon tetrachloride (CCl₄) in mice. Methods. ADMSCs were isolated from inguinal fat pads of enhanced green fluorescent protein (EGFP) transgenic mice and their surface markers and differentiation potential were analyzed. ALF models were established by infusion of CCl₄ and divided into two groups: control group; EGFP-ADMSCs transplantation group. The restoration of biological functions of the livers receiving transplantation was assessed via a variety of approaches such as survival rates, live function parameters, histological localization of EGFP-ADMSCs, and Immunofluorescence analysis. Results. ADMSCs were positive for CD105, CD44 but negative for CD45, CD34 and had adipogenic, osteogenic differentiation potential. The survival rate of transplantation group significantly increased compared to PBS group. Furthermore, the transplanted cells were well integrated into injured livers and produced albumin, cytokeratin-18. Conclusion. Direct transplantation of ADMSCs is an effective treatment for ALF. The transplanted ADMSCs exhibit the potential to differentiate into hepatocyte-like cells in the injured livers.

A cell rolling cytometer reveals the correlation between mesenchymal stem cell dynamic adhesion and differentiation state

This communication presents quantitative studies of the dynamic adhesion behavior of mesenchymal stem cells (MSCs) enabled by the combination of cell-surface receptor-ligand interactions and three-dimensional hydrodynamic control by microtopography.

The chemokine system, and its CCR5 and CXCR4 receptors, as potential targets for personalized therapy in cancer

Chemokines and their receptors regulate the trafficking of leukocytes in hematopoiesis and inflammation, and thus are fundamental to the immune integrity of the host. In parallel, members of the chemokine system exert a large variety of functions that dictate processes of cancer development and progression. Chemokines can act as pro-tumoral or anti-tumoral regulators of malignancy by affecting cells of the tumor microenvironment (leukocytes, endothelial cells, fibroblasts) and the tumor cells themselves (migration, invasion, proliferation, resistance to chemotherapy). Several of the chemokines are generally skewed towards the cancer-promoting direction, including primarily the CCR5-CCL5 (RANTES) and the CXCR4-CXCL12 (SDF-1) axes. This review provides a general view of chemokines and chemokine receptors as regulators of malignancy, describing their multi-faceted activities in cancer. The tumor-promoting activities of the CCR5-CCL5 and CXCR4-CXCL12 pathways are enlightened, emphasizing their potential use as targets for personalized therapy. Indeed, novel blockers of chemokines and their receptors are constantly emerging, and two chemokine receptor inhibitors were recently approved for clinical use: Maraviroc for CCR5 and Plerixafor for CXCR4. The review addresses ongoing pre-clinical and clinical trials using these modalities and others in cancer. Then, challenges and opportunities of personalized therapy directed against chemokines and their receptors in malignancy are discussed, demonstrating that such novel personalized cancer therapies hold many challenges, but also offer hope for cancer patients.

Bone marrow mesenchymal stem cells and liver regeneration: believe the hypoxia!

There are limited data on the efficacy of mesenchymal stem cells (MSCs) in models of extensive hepatic resection. In the previous issue of Stem Cell Research &Therapy, Yu and colleagues demonstrate that transient hypoxic preconditioning of MSCs improves their efficacy in a rat model of massive hepatectomy. This effect appears to be mediated, in part, by increased vascular endothelial growth factor (VEGF) production by the preconditioned MSCs as well as the injured liver. Neutralizing VEGF antibodies ameliorated the benefit of hypoxia-preconditioned MSCs, establishing VEGF as a key mediator of their benefit. This novel approach merits further exploration both mechanistically and to establish the functional advantages of MSCs in other injury settings.

Therapeutic potential of mesenchymal stem cells in regenerative medicine

Mesenchymal stem cells (MSCs) are stromal cells that have the ability to self-renew and also exhibit multilineage differentiation into both mesenchymal and nonmesenchymal lineages. The intrinsic properties of these cells make them an attractive candidate for clinical applications. MSCs are of keen interest because they can be isolated from a small aspirate of bone marrow or adipose tissues and can be easily expanded in vitro. Moreover, their ability to modulate immune responses makes them an even more attractive candidate for regenerative medicine as allogeneic transplant of these cells is feasible without a substantial risk of immune rejection. MSCs secrete various immunomodulatory molecules which provide a regenerative microenvironment for a variety of injured tissues or organ to limit the damage and to increase self-regulated tissue regeneration. Autologous/allogeneic MSCs delivered via the bloodstream augment the titers of MSCs that are drawn to sites of tissue injury and can accelerate the tissue repair process. MSCs are currently being tested for their potential use in cell and gene therapy for a number of human debilitating diseases and genetic disorders. This paper summarizes the current clinical and nonclinical data for the use of MSCs in tissue repair and potential therapeutic role in various diseases.

An in vitro model of human acute ethanol exposure that incorporates CXCR3- and CXCR4-dependent recruitment of immune cells

Alcoholic liver disease (ALD) is one of the commonest causes of cirrhosis and liver failure in the developed world. Hepatic inflammation is the critical stage in progression of both ALD and non-ALD, but it remains difficult to study the underlying mechanisms in a human system, and current animal models do not fully recapitulate human liver disease. We developed a human tissue-based system to study lymphocyte recruitment in response to ethanol challenge. Precision-cut liver slices (PCLS) from human livers were incubated in culture, and hepatic function was determined by albumin production, 3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide assay, glucose uptake responses, and morphometric assessment. Responses of tissue and lymphocytes to ethanol exposure were determined by PCR, flow cytometry, histology, and lymphocyte infiltration assays. Human PCLS demonstrated appropriate upregulation of CYP2E1, ADH1α, and ADH3 in response to ethanol treatment. Ethanol also induced expression of endothelial VCAM-1 and ICAM-1, production of sICAM-1 and CXCL8, and the chemokine receptors CXCR3 and CXCR4 on CD4 and CD8 lymphocytes. CXCR3- and CXCR4-dependent migration of lymphocytes into the tissue increased significantly in response to treatment with ethanol. We have demonstrated that ethanol increases chemokine receptor expression and lymphocyte recruitment into human liver tissue, suggesting that it may operate directly to promote hepatitis in ALD. The physiological and pathophysiological responses of the PCLS to ethanol in vitro highlight the potential of this assay for dissecting the molecular mechanisms underlying human liver inflammation and as a screening tool for novel therapeutics.