Hepatocyte growth factor-mediated attraction of mesenchymal stem cells for apoptotic neuronal and cardiomyocytic cells

The dual role of mesenchymal stem cells in apoptosis regulation

Mesenchymal stem cells (MSCs) are widely distributed pluripotent stem cells with powerful immunomodulatory capacity. MSCs transplantation therapy (MSCT) is widely used in the fields of tissue regeneration and repair, and treatment of inflammatory diseases. Apoptosis is an important way for tissues to maintain cell renewal, but it also plays an important role in various diseases. And many studies have shown that MSCs improves the diseases by regulating cell apoptosis. The regulation of MSCs on apoptosis is double-sided. On the one hand, MSCs significantly inhibit the apoptosis of diseased cells. On the other hand, MSCs also promote the apoptosis of tumor cells and excessive immune cells. Furthermore, MSCs regulate apoptosis through multiple molecules and pathways, including three classical apoptotic signaling pathways and other pathways. In this review, we summarize the current evidence on the regulation of apoptosis by MSCs.

Donor-Matched Peripheral Blood-Derived Mesenchymal Stem Cells Combined With Platelet-Rich Plasma Synergistically Ameliorate Surgery-Induced Osteoarthritis in Rabbits: An In Vitro and In Vivo Study

BACKGROUND

Osteoarthritis (OA) is a common disease that causes joint pain and disability. Stem cell therapy is emerging as a promising treatment for OA.

PURPOSE

To evaluate the ability of peripheral blood-derived mesenchymal stem cells (PBMSCs) combined with donor-matched platelet-rich plasma (PRP) to treat OA in a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

PBMSCs and donor-matched PRP were isolated and prepared from the same rabbit. PBMSCs were treated with serum-free medium, fetal bovine serum, and PRP; a series of PBMSC behaviors, including proliferation, migration, and adhesion, were compared among groups. The ability of PBMSCs or PRP alone and PBMSCs+PRP to protect chondrocytes against proinflammatory cytokine (interleukin 1β [IL-1β]) treatment was compared by analyzing reactive oxygen species (ROS)-scavenging ability and apoptosis. Real-time quantitative polymerase chain reaction and immunofluorescence were used to investigate the expression of extracellular matrix (ECM) metabolism genes and proteins, and Western blotting was used to explore the potential mechanism of the corresponding signaling pathway. In vivo, the effect of PBMSCs+PRP on cartilage and inflammation of the synovium was observed in a surgery-induced OA rabbit model via gross observation, histological and immunohistochemical staining, and enzyme-linked immunosorbent assay.

RESULTS

Proliferation, migration, and adhesion ability were enhanced in PBMSCs treated with PRP. Moreover, compared with either PBMSCs or PRP alone, PBMSCs+PRP enhanced ROS-scavenging ability and inhibited apoptosis in IL-1β-treated chondrocytes. PBMSCs+PRP also reversed the IL-1β-induced degradation of collagen type 2 and aggrecan and increased expression of matrix metalloproteinase 13, and this effect was related to increased expression of ECM synthesis and decreased expression of degradation and inflammatory genes and proteins. Mechanistically, PBMSCs+PRP reduced the phosphorylation of inhibitor of nuclear factor-κBα (IκBα), which further inhibited the phosphorylation of downstream nuclear factor-κB (NF-κB) in the NF-κB signaling pathway. In vivo, compared with PBMSCs or PRP alone, intra-articular (IA) injection of PBMSCs+PRP enhanced cartilage regeneration and attenuated synovial inflammation in OA-induced rabbits.

CONCLUSION

These results demonstrate that PRP could enhance biological activities, including viability, migration, and adhesion, in PBMSCs. PBMSCs+PRP could rescue ECM degeneration by inhibiting inflammatory signaling in IL-1β-treated OA chondrocytes. In addition, IA injection of PBMSCs+PRP effectively attenuated OA progression in a surgery-induced OA rabbit model.

CLINICAL RELEVANCE

PBMSCs+PRP may provide a promising treatment for knee OA, and this study can advance the related basic research.

Emerging roles of growth factors in osteonecrosis of the femoral head

Osteonecrosis of the femoral head (ONFH) is a potentially disabling orthopedic condition that requires total hip arthroplasty in most late-stage cases. However, mechanisms underlying the development of ONFH remain unknown, and the therapeutic strategies remain limited. Growth factors play a crucial role in different physiological processes, including cell proliferation, invasion, metabolism, apoptosis, and stem cell differentiation. Recent studies have reported that polymorphisms of growth factor-related genes are involved in the pathogenesis of ONFH. Tissue and genetic engineering are attractive strategies for treating early-stage ONFH. In this review, we summarized dysregulated growth factor-related genes and their role in the occurrence and development of ONFH. In addition, we discussed their potential clinical applications in tissue and genetic engineering for the treatment of ONFH.

Factor XII protects neurons from apoptosis by epidermal and hepatocyte growth factor receptor-dependent mechanisms

BACKGROUND

Factor XII (FXII) is a serine protease that participates in the intrinsic coagulation pathway. Several studies have shown that plasma FXII exerts a deleterious role in cerebral ischemia and traumatic brain injury by promoting thrombo-inflammation. Nevertheless, the impact of FXII on neuronal cell fate remains unknown.

OBJECTIVES

We investigated the role of FXII and FXIIa in neuronal injury and apoptotic cell death.

METHODS

We tested the neuroprotective roles of FXII and FXIIa in an experimental model of neuronal injury induced by stereotaxic intracerebral injection of N-methyl-D-aspartic acid (NMDA) in vivo and in a model of apoptotic death of murine primary neuronal cultures through serum deprivation in vitro.

RESULTS

Here, we found that exogenous FXII and FXIIa reduce brain lesions induced by NMDA injection in vivo. Furthermore, FXII protects cultured neurons from apoptosis through a growth factor--like effect. This mechanism was triggered by direct interaction with epidermal growth factor (EGF) receptor and subsequent activation of this receptor. Interestingly, the "proteolytically" active and two-chain form of FXII, FXIIa, exerts its protective effects by an alternative signaling pathway. FXIIa activates the pro-form of hepatocyte growth factor (HGF) into HGF, which in turn activated the HGF receptor (HGFR) pathway.

CONCLUSION

This study describes two novel mechanisms of action of FXII and identifies neurons as target cells for the protective effects of single and two-chain forms of FXII. Therefore, inhibition of FXII in neurological disorders may have deleterious effects by preventing its beneficial effects on neuronal survival.

Integrin-specific hydrogels modulate transplanted human bone marrow-derived mesenchymal stem cell survival, engraftment, and reparative activities

Stem cell therapies are limited by poor cell survival and engraftment. A hurdle to the use of materials for cell delivery is the lack of understanding of material properties that govern transplanted stem cell functionality. Here, we show that synthetic hydrogels presenting integrin-specific peptides enhance the survival, persistence, and osteo-reparative functions of human bone marrow-derived mesenchymal stem cells (hMSCs) transplanted in murine bone defects. Integrin-specific hydrogels regulate hMSC adhesion, paracrine signaling, and osteoblastic differentiation in vitro. Hydrogels presenting GFOGER, a peptide targeting α2β1 integrin, prolong hMSC survival and engraftment in a segmental bone defect and result in improved bone repair compared to other peptides. Integrin-specific hydrogels have diverse pleiotropic effects on hMSC reparative activities, modulating in vitro cytokine secretion and in vivo gene expression for effectors associated with inflammation, vascularization, and bone formation. These results demonstrate that integrin-specific hydrogels improve tissue healing by directing hMSC survival, engraftment, and reparative activities.

Platelets and Immune Responses During Thromboinflammation

Besides mediating hemostatic functions, platelets are increasingly recognized as important players of inflammation. Data from experiments in mice and men revealed various intersection points between thrombosis, hemostasis, and inflammation, which are addressed and discussed in this review in detail. One such example is the intrinsic coagulation cascade that is initiated after platelet activation thereby further propagating and re-enforcing wound healing or thrombus formation but also contributing to the pathophysiology of severe diseases. FXII of the intrinsic pathway connects platelet activation with the coagulation cascade during immune reactions. It can activate the contact system thereby either creating an inflammatory state or accelerating inflammation. Recent insights into platelet biology could show that platelets are equipped with complement receptors. Platelets are important for tissue remodeling after injury has been inflicted to the endothelial barrier and to the subendothelial tissue. Thus, platelets are increasingly recognized as more than just cells relevant for bleeding arrest. Future insights into platelet biology are to be expected. This research will potentially offer novel opportunities for therapeutic intervention in diseases featuring platelet abundance.

Johnny on the Spot-Chronic Inflammation Is Driven by HMGB1

Although much has been made of the role of HMGB1 acting as an acute damage associated molecular pattern (DAMP) molecule, prompting the response to tissue damage or injury, it is also released at sites of chronic inflammation including sites of infection, autoimmunity, and cancer. As such, the biology is distinguished from homeostasis and acute inflammation by the recruitment and persistence of myeloid derived suppressor cells, T regulatory cells, fibrosis and/or exuberant angiogenesis depending on the antecedents and the other individual inflammatory partners that HMGB1 binds and focuses, including IL-1β, CXCL12/SDF1, LPS, DNA, RNA, and sRAGE. High levels of HMGB1 released into the extracellular milieu and its persistence in the microenvironment can contribute to the pathogenesis of many if not all autoimmune disorders and is a key factor that drives inflammation further and worsens symptoms. HMGB1 is also pivotal in the maintenance of chronic inflammation and a “wound healing” type of immune response that ultimately contributes to the onset of carcinogenesis and tumor progression. Exosomes carrying HMGB1 and other instructive molecules are released and shape the response of various cells in the chronic inflammatory environment. Understanding the defining roles of REDOX, DAMPs and PAMPs, and the host response in chronic inflammation requires an alternative means for positing HMGB1's central role in limiting and focusing inflammation, distinguishing chronic from acute inflammation.

Pegfilgrastim and linagliptin potentiate chemoattraction of Ccr2 and Cd44 stem cells accompanied by alterations of cardiac Hgf, Igf-1 and Mcp-1 in daunorubicin cardiomyopathy

Objective

Daunorubicin (DAU) downregulates cytokines promoting stem cell migration and homing into the heart, reducing cardiac regeneration after anticancer chemotherapy. Pegfilgrastim (PFIL) protects from DAU-induced neutropenia but its cardioprotective potential remains unclear. We tested whether pegfilgrastim and a dipeptidyl peptidase-4 inhibitor linagliptin, potential enhancers of stem cells migration and homing, would improve DAU-cardiomyopathy.

Methods

DAU (7.5 mg/kg, i.v.) was administered to male Wistar rats to induce cardiotoxicity. Pegfilgrastim (100 µg/kg, s.c.) was administered 24h after DAU, and linagliptin was administered orally for 8 weeks (5 mg/kg/day, LINA). Cardiac damage markers (Nppa, Myh6, Myh7, Gp91phox), cytokines (Sdf-1alpha, Mcp-1, Vegf, Hgf, Igf-1), stem cell markers (Cxcr4, Ccr2, Cd34, Cd133, Cd44, Cd105) were determined by qRT-PCR.

Key findings

Decreased Myh6, elevated Myh7 Nppa, and Gp91phox were not ameliorated by PFIL + LINA. Downregulated expressions of cytokines (Vegf, Sdf-1alpha) and stem cells markers (Cxcr4, Cd34, Cd133, and Cd105) remained decreased after PFIL + LINA. DAU-induced upregulation of Mcp-1, Ccr2 and Cd44 was further potentiated by PFIL + LINA. PFIL + LINA normalised expression of Hgf and Igf-1.

Conclusions

Although PFIL + LINA failed in universal potentiation of stem cells migration and homing, the expression of stem cell markers Ccr2 and Cd44 in the heart potentially increased through the preservation of Hgf, Igf-1 and upregulation of Mcp-1.

Valproic acid stimulates in vitro migration of the placenta-derived mesenchymal stem/stromal cell line CMSC29

Background

The placenta is an abundant source of mesenchymal stem/stromal cells (MSC), but our understanding of their functional properties remains limited. We previously created a placental-derived chorionic MSC (CMSC) cell line to overcome the difficulties associated with conducting extensive ex vivo optimization and experimental work on primary cells. The aim of this study was to characterize the migratory behavior of the CMSC29 cell line in vitro.

Methods

Stimulators of MSC migration, including two cytokines, stromal cell-derived factor-1α (SDF-1α) and hepatocyte growth factor (HGF), and a pharmacological agent, valproic acid (VPA), were tested for their ability to stimulate CMSC29 cell migration. Assessment of cell migration was performed using the xCELLigence Real-Time Cell Analyzer (RTCA).

Results

There was no significant increase in CMSC29 cell migration towards serum free medium with increasing concentration gradients of SDF-1α or HGF. In contrast, treating CMSC29 cells with VPA alone significantly increased their migration towards serum free medium.

Conclusions

Immortalized CMSC29 cells retain important properties of primary CMSC, but their migratory properties are altered. CMSC29 cells do not migrate in response to factors that reportedly stimulate primary MSC/CMSC migration. However, CMSC29 increase their migration in response to VPA treatment alone. Further studies are needed to determine the mechanism by which VPA acts alone to stimulate CMSC29 migration. Still, this study provides evidence that VPA pre-treatment may improve the benefits of cell-based therapies that employ certain MSC sub-types.

Iron oxide nanoparticles promote the migration of mesenchymal stem cells to injury sites

Background

Developing new methods to deliver cells to the injured tissue is a critical factor in translating cell therapeutics research into clinical use; therefore, there is a need for improved cell homing capabilities.

Materials and methods

In this study, we demonstrated the effects of labeling rat bone marrow-derived mesenchymal stem cells (MSCs) with fabricated polydopamine (PDA)-capped Fe₃O₄ (Fe₃O₄@PDA) superparticles employing preassembled Fe₃O₄ nanoparticles as the cores.

Results

We found that the Fe₃O₄@PDA composite superparticles exhibited no adverse effects on MSC characteristics. Moreover, iron oxide nanoparticles increased the number of MSCs in the S-phase, their proliferation index and migration ability, and their secretion of vascular endothelial growth factor relative to unlabeled MSCs. Interestingly, nanoparticles not only promoted the expression of C-X-C chemokine receptor 4 but also increased the expression of the migration-related proteins c-Met and C-C motif chemokine receptor 1, which has not been reported previously. Furthermore, the MSC-loaded nanoparticles exhibited improved homing and anti-inflammatory abilities in the absence of external magnetic fields in vivo.

Conclusion

These results indicated that iron oxide nanoparticles rendered MSCs more favorable for use in injury treatment with no negative effects on MSC properties, suggesting their potential clinical efficacy.

The Platelet Response to Tissue Injury

In recent years, various studies have increasingly explained platelet functions not only in their central role as a regulator in cellular hemostasis and coagulation. In fact, there is growing evidence that under specific conditions, platelets act as a mediator between the vascular system, hemostasis, and the immune system. Therefore, they are essential in many processes involved in tissue remodeling and tissue reorganization after injury or inflammatory responses. These processes include the promotion of inflammatory processes, the contribution to innate and adaptive immune responses during bacterial and viral infections, the modulation of angiogenesis, and the regulation of cell apoptosis in steady-state tissue homeostasis or after tissue breakdown. All in all platelets may contribute to the control of tissue homeostasis much more than generally assumed. This review summarizes the current knowledge of platelets as part of the tissue remodeling network and seeks to provide possible translational implications for clinical therapy.

Highly Efficient In Vitro Reparative Behaviour of Dental Pulp Stem Cells Cultured with Standardised Platelet Lysate Supplementation

Dental pulp is an accessible source of multipotent mesenchymal stromal cells (MSCs). The perspective role of dental pulp stem cells (DPSCs) in regenerative medicine demands an in vitro expansion and in vivo delivery which must deal with the safety issues about animal serum, usually required in cell culture practice. Human platelet lysate (PL) contains autologous growth factors and has been considered as valuable alternative to fetal bovine serum (FBS) in cell cultures. The optimum concentration to be added of such supplement is highly dependent on its preparation whose variability limits comparability of results. By in vitro experiments, we aimed to evaluate a standardised formulation of pooled PL. A low selected concentration of PL (1%) was able to support the growth and maintain the viability of the DPSCs. The use of PL in cell cultures did not impair cell surface signature typically expressed by MSCs and even upregulated the transcription of Sox2. Interestingly, DPSCs cultured in presence of PL exhibited a higher healing rate after injury and are less susceptible to toxicity mediated by exogenous H₂O₂ than those cultured with FBS. Moreover, PL addition was shown as a suitable option for protocols promoting osteogenic and chondrogenic differentiation of DPSCs. Taken together, our results indicated that PL is a valid substitute of FBS to culture and differentiate DPSCs for clinical-grade use.

Rebuilding the Damaged Heart: Mesenchymal Stem Cells, Cell-Based Therapy, and Engineered Heart Tissue

Mesenchymal stem cells (MSCs) are broadly distributed cells that retain postnatal capacity for self-renewal and multilineage differentiation. MSCs evade immune detection, secrete an array of anti-inflammatory and anti-fibrotic mediators, and very importantly activate resident precursors. These properties form the basis for the strategy of clinical application of cell-based therapeutics for inflammatory and fibrotic conditions. In cardiovascular medicine, administration of autologous or allogeneic MSCs in patients with ischemic and nonischemic cardiomyopathy holds significant promise. Numerous preclinical studies of ischemic and nonischemic cardiomyopathy employing MSC-based therapy have demonstrated that the properties of reducing fibrosis, stimulating angiogenesis, and cardiomyogenesis have led to improvements in the structure and function of remodeled ventricles. Further attempts have been made to augment MSCs' effects through genetic modification and cell preconditioning. Progression of MSC therapy to early clinical trials has supported their role in improving cardiac structure and function, functional capacity, and patient quality of life. Emerging data have supported larger clinical trials that have been either completed or are currently underway. Mechanistically, MSC therapy is thought to benefit the heart by stimulating innate anti-fibrotic and regenerative responses. The mechanisms of action involve paracrine signaling, cell-cell interactions, and fusion with resident cells. Trans-differentiation of MSCs to bona fide cardiomyocytes and coronary vessels is also thought to occur, although at a nonphysiological level. Recently, MSC-based tissue engineering for cardiovascular disease has been examined with quite encouraging results. This review discusses MSCs from their basic biological characteristics to their role as a promising therapeutic strategy for clinical cardiovascular disease.

Mesenchymal stem cells in cardiac regeneration: a detailed progress report of the last 6 years (2010-2015)

Mesenchymal stem cells have been used for cardiovascular regenerative therapy for decades. These cells have been established as one of the potential therapeutic agents, following several tests in animal models and clinical trials. In the process, various sources of mesenchymal stem cells have been identified which help in cardiac regeneration by either revitalizing the cardiac stem cells or revascularizing the arteries and veins of the heart. Although mesenchymal cell therapy has achieved considerable admiration, some challenges still remain that need to be overcome in order to establish it as a successful technique. This in-depth review is an attempt to summarize the major sources of mesenchymal stem cells involved in myocardial regeneration, the significant mechanisms involved in the process with a focus on studies (human and animal) conducted in the last 6 years and the challenges that remain to be addressed.

Hepatocyte growth factor and alternative splice variants - expression, regulation and implications in osteogenesis and bone health and repair

INTRODUCTION

Bone marrow-derived mesenchymal stem cells (MSCs) can differentiate into multiple cell types, including osteoblasts, chondrocytes, and adipocytes. These pluripotent cells secrete hepatocyte growth factor (HGF), which regulates cell growth, survival, motility, migration, mitogenesis and is important for tissue development/regeneration. HGF has four splice variants, NK1, NK2, NK3, and NK4 which have varying functions and affinities for the HGF receptor, cMET. HGF promotes osteoblastic differentiation of MSCs into bone forming cells, playing a role in bone development, health and repair.

AREAS COVERED

This review will focus on the effects of HGF in osteogenesis, bone repair and bone health, including structural and functional insights into the role of HGF in the body.

EXPERT OPINION

Approximately 6.2 million Americans experience a fracture annually, with 5-10% being mal- or non-union fractures. HGF is important in priming MSCs for osteogenic differentiation in vitro and is currently being studied to assess its role during bone repair in vivo. Due to the high turnover rate of systemic HGF, non-classic modes of HGF-treatment, including naked-plasmid HGF delivery and the use of HGF splice variants (NK1 & NK2) are being studied to find safe and efficacious treatments for bone disorders, such as mal- or non-union fractures.

In vitro migration and proliferation ("wound healing") potential of mesenchymal stromal cells generated from human CD271(+) bone marrow mononuclear cells

Background

Emerging evidence indicates that mesenchymal stromal cells (MSCs) isolated from different tissue sources may be used in vivo as tissue restorative agents. To date, there is no evidence, however, on migration and proliferation (“wound healing”) potential of different subsets of MSCs. The main goal of this study was therefore to compare the in vitro “wound healing” capacity of MSCs generated from positively selected CD271⁺ bone marrow mononuclear cells (CD271-MSCs) and MSCs generated by plastic adherence (PA-MSCs).

Methods

The in vitro model of wound healing (CytoSelect™ 24-Well Wound Healing Assay) was used in order to compare the migration and proliferation potential of CD271-MSCs and PA-MSCs of passage 2 and 4 cultured in presence or absence of growth factors or cytokines.

Results

CD271-MSCs of both passages when compared to PA-MSCs demonstrated a significantly higher potential to close the wound 12 and 24 h after initiation of the wound healing assay (P < 0.003 and P < 0.002, respectively). Noteworthy, the migration capacity of PA-MSCs of second passage was significantly improved after stimulation with FGF-2 (P < 0.02), PDGF-BB (P < 0.006), MCP-1 (P < 0.002) and IL-6 (P < 0.03), whereas only TGF-β enhanced significantly migration process of PA-MSCs of P4 12 h after the treatment (P < 0.02). Interestingly, treatment of CD271-MSCs of both passages with growth factors or cytokines did not affect their migratory potential.

Conclusions

Our in vitro data provide the first evidence that CD271-MSCs are significantly more potent in “wound healing” than their counterparts PA-MSCs.

Necrotic cell-derived high mobility group box 1 attracts antigen-presenting cells but inhibits hepatocyte growth factor-mediated tropism of mesenchymal stem cells for apoptotic cell death

Tissue damage due to apoptotic or necrotic cell death typically initiates distinct cellular responses, leading either directly to tissue repair and regeneration or to immunological processes first, to clear the site, for example, of potentially damage-inducing agents. Mesenchymal stem cells (MSC) as well as immature dendritic cells (iDC) and monocytes migrate to injured tissues. MSC have regenerative capacity, whereas monocytes and iDC have a critical role in inflammation and induction of immune responses, including autoimmunity after tissue damage. Here, we investigated the influence of apoptotic and necrotic cell death on recruitment of MSC, monocytes and iDC, and identified hepatocyte growth factor (HGF) and the alarmin high mobility group box 1 (HMGB1) as key factors differentially regulating these migratory responses. MSC, but not monocytes or iDC, were attracted by apoptotic cardiomyocytic and neuronal cells, whereas necrosis induced migration of monocytes and iDC, but not of MSC. Only apoptotic cell death resulted in HGF production and HGF-mediated migration of MSC towards the apoptotic targets. In contrast, HMGB1 was predominantly released by the necrotic cells and mediated recruitment of monocytes and iDC via the receptor of advanced glycation end products. Moreover, necrotic cardiomyocytic and neuronal cells caused an HMGB1/toll-like receptor-4-dependent inhibition of MSC migration towards apoptosis or HGF, while recruitment of monocytes and iDC by necrosis or HMGB1 was not affected by apoptotic cells or HGF. Thus, the type of cell death differentially regulates recruitment of either MSC or monocytes and iDC through HGF and HMGB1, respectively, with a dominant, HMGB1-mediated role of necrosis in determining tropism after tissue injury.

Prepubertal children with a history of extra-uterine growth restriction exhibit low-grade inflammation

Intra-uterine growth restriction (IUGR) may induce significant metabolic and inflammatory anomalies, increasing the risk of obesity and CVD later in life. Similarly, alterations in the adipose tissue may lead to metabolic changes in children with a history of extra-uterine growth restriction (EUGR). These mechanisms may induce alterations in immune response during early life. The aim of the present study was to compare pro-inflammatory markers in prepubertal EUGR children with those in a reference population. A total of thirty-eight prepubertal children with a history of EUGR and a reference group including 123 healthy age- and sex-matched children were selected. Perinatal data were examined. In the prepubertal stage, the concentrations of inflammatory biomarkers were measured in both groups. The serum concentrations of C-reactive protein (CRP) and plasma concentrations of hepatocyte growth factor (HGF), IL-6, IL-8, monocyte chemotactic protein type 1 (MCP-1), neural growth factor, TNF-α and plasminogen activator inhibitor type 1 were determined. The plasma concentrations of inflammatory biomarkers CRP, HGF, IL-8, MCP-1 and TNF-α were higher in the EUGR group than in the reference group (P< 0·001). After adjustment for gestational age, birth weight and length, blood pressure values and TNF-α concentrations remained higher in the EUGR group than in the reference group. Therefore, further investigations should be conducted in EUGR children to evaluate the potential negative impact of metabolic, nutritional and pro-inflammatory changes induced by the EUGR condition.

Hepatocyte growth factor and p38 promote osteogenic differentiation of human mesenchymal stem cells

Hepatocyte growth factor (HGF) is a paracrine factor involved in organogenesis, tissue repair, and wound healing. We report here that HGF promotes osteogenic differentiation through the transcription of key osteogenic markers, including osteocalcin, osterix, and osteoprotegerin in human mesenchymal stem cells and is a necessary component for the establishment of osteoblast mineralization. Blocking endogenous HGF using PHA665752, a c-Met inhibitor (the HGF receptor), or an HGF-neutralizing antibody attenuates mineralization, and PHA665752 markedly reduced alkaline phosphatase activity. Moreover, we report that HGF promotion of osteogenic differentiation involves the rapid phosphorylation of p38 and differential regulation of its isoforms, p38α and p38β. Western blot analysis revealed a significantly increased level of p38α and p38β protein, and reverse transcription quantitative PCR revealed that HGF increased the transcriptional level of both p38α and p38β. Using small interfering RNA to reduce the transcription of p38α and p38β, we saw differential roles for p38α and p38β on the HGF-induced expression of key osteogenic markers. In summary, our data demonstrate the importance of p38 signaling in HGF regulation of osteogenic differentiation.

The therapeutic potential of bone marrow-derived mesenchymal stromal cells on hepatocellular carcinoma

Mesenchymal stromal cells (MSCs) are more often obtained from adult and extraembryonic tissues, with the latter sources being likely better from a therapeutic perspective. MSCs show tropism towards inflamed or tumourigenic sites. Mechanisms involved in MSC recruitment into tumours are comprehensively analysed, including chemoattractant signalling axes, endothelial adhesion and transmigration. In addition, signals derived from hepatocellular carcinoma (HCC) tumour microenvironment and their influence in MSC tropism and tumour recruitment are dissected, as well as the present controversy regarding their influence on tumour growth and/or metastasis. Finally, evidences available on the use of MSCs and other selected progenitor/stem cells as vehicles of antitumourigenic genes are discussed. A better knowledge of the mechanisms involved in progenitor/stem cell recruitment to HCC tumours is proposed in order to enhance their tumour targeting which may result in improvements in cell-based gene therapy strategies.

Activated platelets interfere with recruitment of mesenchymal stem cells to apoptotic cardiac cells via high mobility group box 1/Toll-like receptor 4-mediated down-regulation of hepatocyte growth factor receptor MET

Recruitment of mesenchymal stem cells (MSC) following cardiac injury, such as myocardial infarction, plays a critical role in tissue repair and may contribute to myocardial recovery. However, the mechanisms that regulate migration of MSC to the site of tissue damage remain elusive. Here, we demonstrate in vitro that activated platelets substantially inhibit recruitment of MSC toward apoptotic cardiac myocytes and fibroblasts. The alarmin high mobility group box 1 (HMGB1) was released by platelets upon activation and mediated inhibition of the cell death-dependent migratory response through Toll-like receptor (TLR)-4 expressed on the MSC. Migration of MSC to apoptotic cardiac myocytes and fibroblasts was driven by hepatocyte growth factor (HGF), and platelet activation was followed by HMGB1/TLR-4-dependent down-regulation of HGF receptor MET on MSC, thereby impairing HGF-driven MSC recruitment. We identify a novel mechanism by which platelets, upon activation, interfere with MSC recruitment to apoptotic cardiac cells, a process that may be of particular relevance for myocardial repair and regeneration.

Platelets in tissue repair: control of apoptosis and interactions with regenerative cells

Besides mediating primary hemostasis and thrombosis, platelets play a critical role in tissue repair and regeneration. They regulate fundamental mechanisms involved in the healing process including cellular migration, proliferation, and angiogenesis. Control of apoptosis/cell survival and interaction with progenitor cells, which are clinically relevant but poorly understood aspects of platelets in tissue repair, will be highlighted in this review. Gaining deeper insight into the less well-characterized molecular mechanisms is necessary to develop new therapeutic platelet-based options.

Effects of murine and human bone marrow-derived mesenchymal stem cells on cuprizone induced demyelination

For the treatment of patients with multiple sclerosis there are no regenerative approaches to enhance remyelination. Mesenchymal stem cells (MSC) have been proposed to exert such regenerative functions. Intravenous administration of human MSC reduced the clinical severity of experimental autoimmune encephalomyelitis (EAE), an animal model mimicking some aspects of multiple sclerosis. However, it is not clear if this effect was achieved by systemic immunomodulation or if there is an active neuroregeneration in the central nervous system (CNS). In order to investigate remyelination and regeneration in the CNS we analysed the effects of intravenously and intranasally applied murine and human bone marrow-derived MSC on cuprizone induced demyelination, a toxic animal model which allows analysis of remyelination without the influence of the peripheral immune system. In contrast to EAE no effects of MSC on de- and remyelination and glial cell reactions were found. In addition, neither murine nor human MSC entered the lesions in the CNS in this toxic model. In conclusion, MSC are not directed into CNS lesions in the cuprizone model where the blood-brain-barrier is intact and thus cannot provide support for regenerative processes.

Hepatocyte growth factor-loaded biomaterials for mesenchymal stem cell recruitment

Human adult mesenchymal stem cells (MSC) can be readily harvested from bone marrow through aspiration. MSC are involved in tissue regeneration and repair, particularly in wound healing. Due to their high self-renewal capacity and excellent differentiation potential in vitro, MSC are ideally suited for regenerative medicine. The complex interactions of MSC with their environment and their influence on the molecular and functional levels are widely studied but not completely understood. MSC secrete, for example, hepatocyte growth factor (HGF), whose concentration is enhanced in wounded areas and which is shown to act as a chemoattractant for MSC. We produced HGF-loaded biomaterials based on collagen and fibrin gels to develop a recruitment system for endogenous MSC to improve wound healing. Here, we report that HGF incorporated into collagen or fibrin gels leads to enhanced and directed MSC migration in vitro. HGF-loaded biomaterials might be potentially used as in vivo wound dressings to recruit endogenous MSC from tissue-specific niches towards the wounded area. This novel approach may help to reduce costly multistep procedures of cell isolation, in vitro culture, and transplantation usually used in tissue engineering.

Autologous bone marrow-derived mesenchymal stem cell transplantation promotes liver regeneration after portal vein embolization in cirrhotic rats

BACKGROUND

Preexisting cirrhosis usually leads to an inadequate and delayed regeneration of the future liver remnant (FLR) after portal vein embolization (PVE). Bone marrow-derived mesenchymal stem cells (BMSC) are promising candidates for therapeutic applications in liver diseases. In this study, the efficacy of autologous BMSCs transplantation to promote FLR regeneration was investigated in a rat cirrhotic model.

METHODS

Autologous BMSCs were expanded and labeled with PKH26, and then were injected immediately into nonembolized lobes after PVE through portal vein in cirrhotic rat. At 7, 14, and 28 d after this, liver weight and Ki-67 labeling index were measured, and blood analysis was performed. Cirrhotic degree of FLR was assessed by hydroxyproline content assay and histopathology. Gene expressions of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), interleukin-10 (IL-10), and matrix metalloproteinase-9 (MMP-9) were detected with real-time reverse transcriptase-polymerase chain reaction. Distribution and hepatocyte differentiation of BMSCs in FLR were determined by confocal microscopy.

RESULTS

Autologous BMSCs significantly increased the FLR weight ratio to the total liver and the Ki-67 labeling index, and serum albumin levels were significantly higher and total bilirubin levels were significantly lower in the BMSCs group compared with the controls without BMSCs transplantation 14 and 28 d post-PVE. BMSCs significantly decreased the hydroxyproline content and collagen accumulation, up-regulated the expressions of HGF, IL-10, VEGF, and MMP-9 28 d post-PVE, and expressed hepatocyte-specific markers, such as α-fetoprotein, cytokeratin 18, and albumin in a time-dependent manner in FLR.

CONCLUSIONS

Autologous BMSCs can differentiate into hepatocyte and promote FLR regeneration after PVE in cirrhotic liver, which may be through improving local microenvironment by decreasing cirrhosis, up-regulating the gene expressions of VEGF, HGF, IL-10, and MMP-9.

Migration of mesenchymal stem cells towards glioblastoma cells depends on hepatocyte-growth factor and is enhanced by aminolaevulinic acid-mediated photodynamic treatment

Hepatocyte-growth factor (HGF) is expressed by glioblastomas and contributes to their growth, migration and invasion. HGF also mediates migration of mesenchymal stem cells (MSC) to sites of apoptotic cell death. Moreover, MSC show tropism for glioblastomas, which is exploited in gene therapy to deliver the therapeutics to the tumor cells. Here, we have studied whether HGF contributes to the recruitment of MSC by glioblastoma cells and whether aminolaevulinic acid-mediated photodynamic therapy (ALA/PDT), a novel therapeutic approach that induces apoptosis in glioblastoma cells, affects HGF release and this migratory response. MSC expressed the HGF receptor MET and migrated towards U87 and U251 glioblastoma spheroids. Migration increased significantly when spheroids were subjected to ALA/PDT, which was associated with induction of apoptosis and up-regulation of HGF. Neutralizing HGF resulted in significant inhibition of MSC migration towards untreated as well as ALA/PDT-treated spheroids. Thus, glioblastoma cells express HGF, which contributes to the attraction of MSC. ALA/PDT induces apoptosis and augments HGF release causing enhanced MSC migration towards the tumor cells. ALA/PDT may therefore be exploited to improve targeting of MSC delivered gene therapy, but it may also constitute a risk in terms of beneficial effects for the tumor.

High targeted migration of human mesenchymal stem cells grown in hypoxia is associated with enhanced activation of RhoA

INTRODUCTION

A feature which makes stem cells promising candidates for cell therapy is their ability to migrate effectively into damaged or diseased tissues. Recent reports demonstrated the increased motility of human mesenchymal stem cells (hMSC) grown under hypoxic conditions compared to normoxic cells. However, the directional migration of hMSC cultured in hypoxia has not been investigated. In this study we examined the in vitro transmembrane migration of hMSC permanently cultured in hypoxia in response to various cytokines. We also studied the involvement of RhoA, a molecule believed to play an essential role in the migration of MSC via reorganization of the cytoskeleton.

METHODS

We compared the directional migration of human hMSCs grown permanently under normal (21%, normoxic) and low O2 (5%, hypoxic) conditions until passage 4 using an in vitro transmembrane migration assay. A series of 17 cytokines was used to induce chemotaxis. We also compared the level of GTP-bound RhoA in the cell extracts of calpeptin-activated hypoxic and normoxic hMSC.

RESULTS

We found that hMSC cultured in hypoxia demonstrate markedly higher targeted migration activity compared to normoxic cells, particularly towards wound healing cytokines, including those found in ischemic and myocardial infarction. We also demonstrated for the first time that hMSC are dramatically more sensitive to activation of RhoA.

CONCLUSIONS

The results of this study indicate that high directional migration of hMSCs permanently grown in hypoxia is associated with the enhanced activation of RhoA. The enhanced migratory capacity of hypoxic hMSC would further suggest their potential advantages for clinical applications.

Concise review: the potential of stromal cell-derived factor 1 and its receptors to promote stem cell functions in spinal cord repair

Transplanted stem cells provide beneficial effects on regeneration/recovery after spinal cord injury (SCI) by the release of growth-promoting factors, increased tissue preservation, and provision of a permissive environment for axon regeneration. A rise in chemokine stromal cell-derived factor 1 (SDF-1/CXCL12) expression levels in central nervous system (CNS) injury sites has been shown to play a central role in recruiting transplanted stem cells. Although technically more challenging, it has been shown that after SCI few endogenous stem cells are recruited via SDF-1/CXCR4 signaling. Evidence is accumulating that increasing SDF-1 levels at the injury site (e.g., by exogenous application or transfection methods) further enhances stem cell recruitment. Moreover, SDF-1 might, in addition to migration, also influence survival, proliferation, differentiation, and cytokine secretion of stem cells. Here, we discuss the experimental data available on the role of SDF-1 in stem and progenitor cell biology following CNS injury and suggest strategies for how manipulation of the SDF-1 system could facilitate stem cell-based therapeutic approaches in SCI. In addition, we discuss challenges such as how to circumvent off-target effects in order to facilitate the transfer of SDF-1 to the clinic.

Various types of stem cells, including a population of very small embryonic-like stem cells, are mobilized into peripheral blood in patients with Crohn's disease

BACKGROUND

Developmentally early cells, including hematopoietic stem progenitor cells (HSPCs), mesenchymal stem cells (MSCs), endothelial progenitor cells (EPCs), and very small embryonic-like stem cells (VSELs), are mobilized into peripheral blood (PB) in response to tissue/organ injury. We sought to determine whether these cells are mobilized into PB in patients with Crohn's disease (CD).

METHODS

Twenty-five patients with active CD, 20 patients in clinical remission, and 25 age-matched controls were recruited and PB samples harvested. The circulating CD133+/Lin-/CD45+ and CD34+/Lin-/CD45+ cells enriched for HSPCs, CD105+/STRO-1+/CD45- cells enriched for MSCs, CD34+/KDR+/CD31+/CD45-cells enriched for EPCs, and small CXCR4+CD34+CD133+ subsets of Lin-CD45- cells that correspond to the population of VSELs were counted by fluorescence-activated cell sorting (FACS) and evaluated by direct immunofluorescence staining for pluripotency embryonic markers and by reverse-transcription polymerase chain reaction (RT-PCR) for expression of messenger (m)RNAs for a panel of genes expressed in intestine epithelial stem cells. The serum concentration of factors involved in stem cell trafficking, such as stromal derived factor-1 (SDF-1), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF) were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our data indicate that cells expressing markers for MSCs, EPCs, and small Oct-4+Nanog+SSEA-4+CXCR4+lin-CD45- VSELs are mobilized into PB in CD. The mobilized cells also expressed at the mRNA level genes playing a role in development and regeneration of gastrointestinal epithelium. All these changes were accompanied by increased serum concentrations of VEGF and HGF.

CONCLUSIONS

CD triggers the mobilization of MSCs, EPCs, and VSELs, while the significance and precise role of these mobilized cells in repair of damaged intestine requires further study.

Effects of hepatocyte growth factor overexpressed bone marrow-derived mesenchymal stem cells on prevention from left ventricular remodelling and functional improvement in infarcted rat hearts

Bone marrow-derived mesenchymal stem cells (BM-MSCs ) transplantation has been reported to be a promising therapy for myocardial infarction (MI). However, low survival rate of BM-MSCs in infarcted heart is one of the major limitations for the perspective clinical application. In this study, we aimed to investigate the effect of hepatocyte growth factor (HGF) on left ventricular function improvement of HGF gene-modified BM-MSCs (HGF-MSCs) after its delivery into the infarcted rat hearts. BM-MSCs were isolated with fibroblast-like morphology and expressed CD44+CD29+CD90+/CD34-CD45-CD31-CD11a. After 5-azacytidine induction in vitro, 20%-30% of the cells were positively stained for desmin, cardiac-specific cardiac troponin I and connexin-43. Histological staining revealed that 2 weeks after MI is an optimal time point with decreased neutrophil infiltration and increased vascular number. Minimal infarct size and best haemodynamic analysis were also observed after cell injection at 2 weeks compared with that of 1 h, 1 week or 4 weeks. Echocardiogram confirmed that transplantation with HGF-MSCs significantly improved left ventricular function compared with other groups in rat MI models. MSCs and HGF-MSCslabelled with DAPI were detected 4 weeks after MI in the infarcted area. Decreased infarcted scar area and increased angiogenesis formation could be found in HGF-MSCs group than in other groups as demonstrated by hematoxylin and eosin (H&E) staining and factor VIII staining. These results indicate that HGF-MSCs transplantation could enhance the contractile function and attenuate left ventricular remodelling efficiently in rats with MI.

Therapeutic potential of adult bone marrow-derived mesenchymal stem cells in diseases of the skeleton

Mesenchymal stem cells (MSCs) are the most popular among the adult stem cells in tissue engineering and regenerative medicine. Since their discovery and functional characterization in the late 1960s and early 1970s, MSCs or MSC-like cells have been obtained from various mesodermal and non-mesodermal tissues, although majority of the therapeutic applications involved bone marrow-derived MSCs. Based on its mesenchymal origin, it was predicted earlier that MSCs only can differentiate into mesengenic lineages like bone, cartilage, fat or muscle. However, varied isolation and cell culturing methods identified subsets of MSCs in the bone marrow which not only differentiated into mesenchymal lineages, but also into ectodermal and endodermal derivatives. Although, true pluripotent status is yet to be established, MSCs have been successfully used in bone and cartilage regeneration in osteoporotic fracture and arthritis, respectively, and in the repair of cardiac tissue following myocardial infarction. Immunosuppressive properties of MSCs extend utility of MSCs to reduce complications of graft versus host disease and rheumatoid arthritis. Homing of MSCs to sites of tissue injury, including tumor, is well established. In addition to their ability in tissue regeneration, MSCs can be genetically engineered ex vivo for delivery of therapeutic molecule(s) to the sites of injury or tumorigenesis as cell therapy vehicles. MSCs tend to lose surface receptors for trafficking and have been reported to develop sarcoma in long-term culture. In this article, we reviewed the current status of MSCs with special emphasis to therapeutic application in bone-related diseases.