Gene expression profile of adult human bone marrow-derived mesenchymal stem cells stimulated by the chemokine CXCL7

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.

Bronchial epithelial gene expression and interstitial lung abnormalities

INTRODUCTION

Interstitial lung abnormalities (ILA) often represent early fibrotic changes that can portend a progressive fibrotic phenotype. In particular, the fibrotic subtype of ILA is associated with increased mortality and rapid decline in lung function. Understanding the differential gene expression that occurs in the lungs of participants with fibrotic ILA may provide insight into development of a useful biomarker for early detection and therapeutic targets for progressive pulmonary fibrosis.

METHODS

Measures of ILA and gene expression data were available in 213 participants in the Detection of Early Lung Cancer Among Military Personnel (DECAMP1 and DECAMP2) cohorts. ILA was defined using Fleischner Society guidelines and determined by sequential reading of computed tomography (CT) scans. Primary analysis focused on comparing gene expression in ILA with usual interstitial pneumonia (UIP) pattern with those with no ILA.

RESULTS

ILA was present in 51 (24%) participants, of which 16 (7%) were subtyped as ILA with a UIP pattern. One gene, pro platelet basic protein (PPBP) and seventeen pathways (e.g. TNF-α signalling) were significantly differentially expressed between those with a probable or definite UIP pattern of ILA compared to those without ILA. 16 of these 17 pathways, but no individual gene, met significance when comparing those with ILA to those without ILA.

CONCLUSION

Our study demonstrates that abnormal inflammatory processes are apparent in the bronchial airway gene expression profiles of smokers with and without lung cancer with ILA. Future studies with larger and more diverse populations will be needed to confirm these findings.

The Role of Mesenchymal Stem Cells in the Induction of Cancer-Stem Cell Phenotype

Cancer stem cells (CSCs) modify and form their microenvironment by recruiting and activating specific cell types such as mesenchymal stem cells (MSCs). Tumor-infiltrating MSCs help to establish a suitable tumor microenvironment for the restoration of CSCs and tumor progression. In addition, crosstalk between cancer cells and MSCs in the microenvironment induces a CSC phenotype in cancer cells. Many mechanisms are involved in crosstalk between CSCs/cancer cells and MSCs including cell-cell interaction, secretion of exosomes, and paracrine secretion of several molecules including inflammatory mediators, cytokines, and growth factors. Since this crosstalk may contribute to drug resistance, metastasis, and tumor growth, it is suggested that blockade of the crosstalk between MSCs and CSCs/cancer cells can provide a new avenue to improving the cancer therapeutic tools. In this review, we will discuss the role of MSCs in the induction of cancer stem cell phenotype and the restoration of CSCs. We also discuss targeting the crosstalk between MSCs and CSCs/cancer cells as a therapeutic strategy.

Transcriptome profiling in head kidney of rainbow trout (Oncorhynchus mykiss) after infection with the low-virulent Nagano genotype of infectious hematopoietic necrosis virus

Infectious hematopoietic necrosis virus (IHNV) causes clinical diseases and mortality in a wide variety of salmonid species. Here, we studied transcriptional responses in rainbow trout infected by the IHNV-Nagano strain isolated in Korea. RNA-seq-based transcriptome analysis of head kidney tissues cataloged differentially expressed genes. Enrichment analysis of gene ontology annotations was performed, and a total of fifteen biological process terms were commonly identified at all time points. In the Kyoto Encyclopedia of Genes and Genomes pathway analysis, pathogen recognition receptor (PRR) signaling pathways such as the retinoic-acid-inducible gene-I-like receptor signaling pathway and the Toll-like receptor signaling pathway were identified at all time points. The nucleotide-binding oligomerization-domain-like receptor signaling pathway and cytosolic DNA-sensing pathway were identified at days 1 and 3. Protein-protein interaction network and centrality analyses revealed that the immune system, signaling molecules, and interaction pathways were upregulated at days 1 and 3, with the highest centrality of tumor necrosis factor. Cancer, cellular community, and endocrine system pathways were downregulated, with the highest centrality of fibronectin 1 at day 5. STAT1 was upregulated from days 1 to 5 with a high centrality. The reproducibility and repeatability of the transcriptome analysis were validated by RT-qPCR. IHNV-Nagano infection dynamically changed the transcriptome profiles in the head kidney of rainbow trout and induced a defense mechanism by regulating the immune and inflammatory pathways through PRR signaling at an early stage. Downregulated pathways involved in extracellular matrix formation and focal adhesion at day 5 indicated the possible failure of wound healing, which is important in the pathogenesis of IHNV infection.

Bioactive zinc-doped sol-gel coating modulates protein adsorption patterns and in vitro cell responses

Zinc is an essential element with an important role in stimulating the osteogenesis and mineralization and suppressing osteoclast differentiation. In this study, new bioactive ZnCl₂-doped sol-gel materials were designed to be applied as coatings onto titanium. The biomaterials were physicochemically characterized and the cellular responses evaluated in vitro using MC3T3-E1 osteoblasts and RAW264.7 macrophages. The effect of Zn on the adsorption of human serum proteins onto the material surface was evaluated through nLC-MS/MS. The incorporation of Zn did not affect the crosslinking of the sol-gel network. A controlled Zn²⁺ release was obtained, reaching values below 10 ppm after 21 days. The materials were no cytotoxic and lead to increased gene expression of ALP, TGF-β, and RUNX2 in the osteoblasts. In macrophages, an increase of IL-1β, TGF-β, and IL-4 gene expression was accompanied by a reduced TNF-α liberation. Proteomic results showed changes in the adsorption patterns of proteins associated with immunological, coagulative, and regenerative functions, in a Zn dose-dependent manner. The variations in protein adsorption might lead to the downregulation of the NF-κB pathway, thus explain the observed biological effects of Zn incorporation into biomaterials. Overall, these coatings demonstrated their potential to promote bone tissue regeneration.

Congenital muscular dystrophy-associated inflammatory chemokines provide axes for effective recruitment of therapeutic adult stem cell into muscles

Background

Congenital muscular dystrophies (CMD) are a clinically and genetically heterogeneous group of neuromuscular disorders characterized by muscle weakness. The two most prevalent forms of CMD, collagen VI-related myopathies (COL6RM) and laminin α2 deficient CMD type 1A (MDC1A), are both caused by deficiency or dysfunction of extracellular matrix proteins. Previously, we showed that an intramuscular transplantation of human adipose-derived stem cells (ADSC) into the muscle of the Col6a1^−/− mice results in efficient stem cell engraftment, migration, long-term survival, and continuous production of the collagen VI protein, suggesting the feasibility of the systemic cellular therapy for COL6RM. In order for this therapeutic approach to work however, stem cells must be efficiently targeted to the entire body musculature. Thus, the main goal of this study is to test whether muscle homing of systemically transplanted ADSC can be enhanced by employing muscle-specific chemotactic signals originating from CMD-affected muscle tissue.

Methods

Proteomic screens of chemotactic molecules were conducted in the skeletal muscles of COL6RM- and MDC1A-affected patients and CMD mouse models to define the inflammatory and immune activities, thus, providing potential markers of disease activity or treatment effect. Also using a pre-clinical animal model, recapitulating mild Ullrich congenital muscular dystrophy (UCMD), the therapeutic relevance of identified chemotactic pathways was investigated in vivo, providing a basis for future clinical investigations.

Results

Comprehensive proteomic screens evaluating relevant human and mouse skeletal muscle biopsies offered chemotactic axes to enhance directional migration of systemically transplanted cells into CMD-affected muscles, including CCL5-CCR1/3/5, CCL2-CCR2, CXCL1/2-CXCR1,2, and CXCL7-CXCR2. Also, the specific populations of ADSC selected with an affinity for the chemokines being released by damaged muscle showed efficient migration to injured site and presented their therapeutic effect.

Conclusions

Collectively, identified molecules provided insight into the mechanisms governing directional migration and intramuscular trafficking of systemically infused stem cells, thus, permitting broad and effective application of the therapeutic adult stem cells for CMD treatment.

Mesenchymal stem cells maintain the stemness of colon cancer stem cells via interleukin-8/mitogen-activated protein kinase signaling pathway

Mesenchymal stem cells (MSCs) can act as a carrier in tumor therapy, and tumor suppressor gene-modified MSCs can reach and suppress the tumor. However, in the colon cancer microenvironment, MSCs could promote tumor growth and create the environment that is conducive to the survival of cancer stem cells (CSCs). This study discovered MSCs from three sources (bone marrow, adipose, placenta) could induce the stemness and epithelial–mesenchymal transition (EMT) of HCT116 in vitro, meanwhile adipose- and placenta-derived MSCs increase the proportion of CD133+/CD44+ HCT116. Then, we explored the interaction mechanism between CD133+/CD44+ HCT116 and MSCs by the bioinformatics and in vitro assays. After CD133+/CD44+ HCT116 were co-cultured with MSCs, many cytokines in MSCs were stimulated, including interleukin-8 (IL-8). The binding of IL-8/CXCR2 activates the downstream mitogen-activated protein kinase (MAPK) signaling pathway in colon CSCs, thereby promoting the stemness and EMT. However, inhibition of IL-8/CXCR2/Erk1/2 could reverse the effect of MSCs on CSC stemness. In addition, MSCs co-cultured with CD133+/CD44+ HCT116 produce a carcinoma-associated fibroblast phenotype via intracellular FGF10–PKA–Akt–β-catenin signaling, which can be attenuated by IL-8 peptide inhibitor. To conclude, IL-8 promotes the interaction between colon CSCs and MSCs, and activates the MAPK signaling pathway in colon CSCs, which provides a theoretical basis for the application of MSCs in clinical practice.

IMPACT STATEMENT

MSCs have the property of chemotaxis and they can migrate to the tumor site by paracrine pathway in the tumor environment, and then interact with tumor cells. Although a mass of studies have been conducted about the impact of MSCs on tumors, it is still controversial whether the exogenous MSCs promote or inhibit tumor growth. In this work, we evaluated the effects of MSCs from three sources (bone marrow, adipose, placenta) on the proliferation, stemness, and metastasis of the colon cancer cells both in vitro and in vivo. Then, we proved the IL-8/CXCR2/MAPK and FGF10–PKA–Akt–β-catenin signaling pathway which mediate the interplay between MSC and CD133+/CD44+ colon cancer cell. This research aims to provide a theoretical basis for the safe application of MSCs in the clinical treatment of colon cancer.

Articular cartilage regeneration: The role of endogenous mesenchymal stem/progenitor cell recruitment and migration

BACKGROUND

Trauma- or osteoarthritis-related cartilage damage resulted in functional decline of joints and heavy burden of public health. Recently, the reparative role of mesenchymal stem/progenitor cells (MSCs) in articular cartilage (AC) reconstruction is drawing more and more attention.

OBJECTIVE

To provide a review on (1) the locations and categories of joint-resident MSCs, (2) the regulation of chondrogenic capacities of MSCs, (3) the migratory approaches of MSCs to diseased AC and regulatory mechanisms.

METHODS

PubMed and Web of Science were searched for English-language articles related to MSC recruitment and migration for AC repair until June 2019. The presence of various MSCs in or around joints, the potential approaches to diseased AC` and the regenerative capacities of MSCs were reviewed.

RESULTS

Various intra- and peri-articular MSCs, with inherent migratory potentials, are present in multiple stem cell niches in or around joints. The recruitment and migration of joint-resident MSCs play crucial roles in endogenous AC repair. Multiple recruiting signals, such as chemokines, growth factors, etc., emerge during the development of AC diseases and participate in the regulation of MSC mobilization. Motivated MSCs could migrate into cartilage lesions and then exert multiple reparative potentials, including extracellular matrix (ECM) reconstruction and microenvironment modulation.

CONCLUSION

In general, AC repair based on endogenous MSC recruitment and migration is a feasible strategy, and a promising research field. Furthermore, endogenous AC repair mediated by native MSCs would provide new opportunities to efficient preventative or therapeutic options for AC diseases.

Improved magnetic regulation of delivery profiles from ferrogels

While providing the ability to magnetically enhance delivery rates, ferrogels have not been able to produce the various types of regulated delivery profiles likely needed to direct complex biological processes. For example, magnetically triggered release after prolonged periods of payload retention have not been demonstrated and little has been accomplished towards remotely controlling release rate through alterations in the magnetic signal. Also, strategies do not exist for magnetically coordinating multi-drug sequences. The purpose of this study was to develop these capabilities through improved ferrogel design and investigating how alterations in the magnetic signal impact release characteristics. Results show that delivery rate can be remotely regulated using the frequency of magnetic stimulation. When using an optimized biphasic ferrogel design, stimulation at optimized frequencies enabled magnetically triggered deliveries after a delay of 5 days that were 690- to 1950-fold higher than unstimulated baseline values. Also, a sequence of two payloads was produced by allowing one payload to initially diffuse out of the ferrogel, followed by magnetically triggered release of a different payload on day 5. Finally, it was demonstrated that two payloads could be sequentially triggered for release by first stimulating at a frequency tuned to preferentially release one payload (after 24 h), followed by stimulation at a different frequency tuned to preferentially release the other payload (After 4 days). The strategies developed here may expand the utility of ferrogels in clinical scenarios where the timing and sequence of biological events can be tuned to optimize therapeutic outcome.

The effect of endothelial cell activation and hypoxia on placental chorionic mesenchymal stem/stromal cell migration

INTRODUCTION

Chorionic mesenchymal stem/stromal cells (CMSC) can be isolated from the placenta in large numbers. Although their functions are yet to be fully elucidated, they have a role in tissue development and repair. To fulfil such a role, CMSC must be able to migrate to the microenvironment of the injury site. This process is not fully understood and the aim of this study therefore, was to examine in vitro CMSC migration in response to tissue inflammation and hypoxic conditioning.

METHODS

CMSC were derived from the chorionic villi. A trans-endothelium migration (TEM) assay was used to study CMSC migration through an activated endothelial cell monolayer using the HMEC-1 cell line. A cytokine array was used to identify and compare the cytokine production profile of activated versus non-activated HMEC-1.

RESULTS

There were significant changes in cytokine production by HMEC-1 cells following lipopolysaccharide (LPS) treatment and hypoxic conditioning. Despite this, results from the TEM assay showed no significant change in the average number of CMSC that migrated through the LPS activated HMEC-1 layer compared to the untreated control. Furthermore, there was no significant change in the average number of CMSC that migrated through the HMEC-1 monolayer when exposed to hypoxic (1% O₂), normoxic (8% O₂) or hyperoxic (21% O₂) conditions.

CONCLUSION

These data suggest that cell functions such as transendothelial migration can vary between MSC derived from different tissues in response to the same biological cues.

Bone Marrow-Derived Mesenchymal Stromal Cells from Patients with Sickle Cell Disease Display Intact Functionality

Hematopoietic cell transplantation (HCT) is the only cure for sickle cell disease (SCD), but engraftment remains challenging in patients lacking matched donors. Infusion of mesenchymal stromal cells (MSCs) at the time of HCT may promote hematopoiesis and ameliorate graft-versus-host disease. Experimental murine models suggest MSC major histocompatibility complex compatibility with recipient impacts their in vivo function, suggesting autologous MSCs could be superior to third-party MSCs for promoting HCT engraftment. Here we tested whether bone marrow (BM)-derived MSCs from SCD subjects have comparable functionality compared with MSCs from healthy volunteers. SCD MSC doubling time and surface marker phenotype did not differ significantly from non-SCD. Third-party and autologous (SCD) T cell proliferation was suppressed in a dose-dependent manner by all MSCs. SCD MSCs comparably expressed indoleamine-2,3-dioxygenase, which based on transwell and blocking experiments appeared to be the dominant immunomodulatory pathway. The expression of key genes involved in hematopoietic stem cell (HSC)-MSC interactions was minimally altered between SCD and non-SCD MSCs. Expression was, however, altered by IFN-γ stimulation, particularly CXCL14, CXCL26, CX3CL1, CKITL, and JAG1, indicating the potential to augment MSC expression by cytokine stimulation. These data demonstrate the feasibility of expanding BM-derived MSCs from SCD patients that phenotypically and functionally do not differ per International Society of Cell Therapy essential criteria from non-SCD MSCs, supporting initial evaluation (primarily for safety) of autologous MSCs to enhance haploidentical HSC engraftment in SCD.

Chemotaxis-driven disease-site targeting of therapeutic adult stem cells in dystrophic epidermolysis bullosa

Background

Dystrophic epidermolysis bullosa (DEB), a rare genodermatosis, is characterized by the formation of intra-epidermal blistering and the development of chronic nonhealing skin wounds. Recently, attempts have been made to develop cell-based therapies for this currently intractable disorder. The molecular mechanisms that govern directional migration of the adult stem cells, allowing their efficient and controlled homing to the skin affected with DEB, are poorly understood. The key mechanism that regulates recruitment of leukocytes and progenitor stem cells to distal anatomical tissues affected with disease is chemotaxis, which depends on the signaling molecules, chemokines, and acts primarily as part of the host defense and repair mechanism.

Methods

Comprehensive proteomic screening of chemokines in the blister fluids of DEB-affected mice was conducted to define the inflammatory and immune activities, thus providing potential to examine local biological mechanisms and define the protein signature within lesional skin as a potential marker of disease activity. Also, the therapeutic relevance of identified chemotactic pathways was investigated in vivo, providing a basis for future clinical investigations.

Results

Assessment of blister fluid-derived chemokines showed a persistent presence of several chemotactic molecules, including CXCL1 + 2 and CXCL5. The majority of blister-originated chemotactic signals were associated with preferential recruitment of CD45⁺CXCR2⁺ and CD11b⁺CXCR2⁺ leukocytes. Systemic transplantation of an enriched CXCR2 population of mouse adipose-derived stem cells (mADSC) into DEB-affected mice demonstrated effective recruitment of cells to the blistering skin under the influence of blister-derived ligands and deposition of therapeutic type VII collagen.

Conclusions

Collectively, these studies demonstrate that recruitment of mADSC into DEB skin is tightly controlled by disease-site chemotactic activities and suggest a potential mechanism for effective application of therapeutic stem cells for DEB.

Study on chemotaxis and chemokinesis of bone marrow-derived mesenchymal stem cells in hydrogel-based 3D microfluidic devices

Background

Controlling the fate of mesenchymal stems cells (MSCs) including proliferation, migration and differentiation has recently been studied by many researchers in the tissue engineering field. Especially, recruitment of stem cells to injury sites is the first and crucial step in tissue regeneration. Although significant progress has been made in the chemotactic migration of MSCs, MSC migration in three dimensional environments remains largely unknown. We developed a 3D hydrogel-based microfluidic-device to study the migration behavior of human MSCs in the presence of stromal-cell derived factor-1α (SDF-1α), interleukin 8 (IL-8) and Substance P (SP) which have been utilized as chemoattractant candidates of human mesenchymal stem cells (hMSCs).

Results

We systematically investigated the chemotactic migration behaviors of hMSCs and their responses to SDF-1α, IL-8, and SP. SDF-1α was shown to be the most fascinating chemoattractant candidate among those factors at a certain time point. We also found that each chemokine showed different chemoattractant abilities according to their concentration. In the case of SP, this factor showed chemokinesis not chemotaxis. Especially at a 7–8 × 10⁻⁸ M concentration range, the chemokinesis ability driven by SP was further increased. The data suggest that some factors at the optimal concentration exhibit chemokinesis or chemotaxis in a 3D hydrogel-based microfluidic device.

Conclusion

In this study on chemotaxis and chemokinesis of hMSCs, the system parameters such as chemokine concentration, system stability, and 2D or 3D microenvironment are critically important to obtain meaningful results.

NAP-2 Secreted by Human NK Cells Can Stimulate Mesenchymal Stem/Stromal Cell Recruitment

Strategies for improved homing of mesenchymal stem cells (MSCs) to a place of injury are being sought and it has been shown that natural killer (NK) cells can stimulate MSC recruitment. Here, we studied the chemokines behind this recruitment. Assays were performed with bone marrow human MSCs and NK cells freshly isolated from healthy donor buffy coats. Supernatants from MSC-NK cell co-cultures can induce MSC recruitment but not to the same extent as when NK cells are present. Antibody arrays and ELISA assays confirmed that NK cells secrete RANTES (CCL5) and revealed that human NK cells secrete NAP-2 (CXCL7), a chemokine that can induce MSC migration. Inhibition with specific antagonists of CXCR2, a receptor that recognizes NAP-2, abolished NK cell-mediated MSC recruitment. This capacity of NK cells to produce chemokines that stimulate MSC recruitment points toward a role for this immune cell population in regulating tissue repair/regeneration.

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Primary unstimulated human NK cells produce NAP-2 (CXCL7)

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NAP-2 is a chemokine that can promote recruitment of bone marrow MSCs

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Inhibiting the NAP-2 receptor CXCR2 abolishes NK cell-mediated MSC recruitment

Increased migration of human mesenchymal stromal cells by autocrine motility factor (AMF) resulted in enhanced recruitment towards hepatocellular carcinoma

Background and Aims

Several reports described the migration of human mesenchymal stromal cells (MSCs) towards tumor-released factors. Autocrine motility factor (AMF) is produced by several tumors including hepatocellular carcinoma (HCC). The aim of this study was to analyze AMF involvement on MSC migration towards human HCC.

Methods

Production of AMF by HCC tumors was evaluated by western analysis. The effects of AMF on MSCs from different sources (bone marrow, adipose tissue and perivascular cells from umbilical cord) were analyzed using in vitro migration assay; metalloproteinase 2 (MMP2) activity and expression of critical genes were studied by zymography and qRT-PCR, respectively. To assess AMF involvement on the in vivo MSC migration, noninvasive fluorescence imaging was performed. To test the effect of AMF-primed MSCs on tumor development, in vitro proliferation and spheroids growth and in vivo tumor volume were evaluated.

Results

AMF produced by HCC was found to induce migration of different MSCs in vitro and to enhance their MMP2 activity. Stimulation of MSCs with recombinant AMF (rAMF) also induced the in vitro adhesion to endothelial cells in coincidence with changes in the expression levels of MMP3, AMF receptor, caveolin-1, and -2 and GDI-2. Importantly, stimulation of MSCs with rAMF increased the in vivo migration of MSCs towards experimental HCC tumors. AMF-priming of MSCs did not induce a pro-tumorigenic effect on HCC cells neither in vivo nor in vitro.

Conclusion

AMF plays a role in MSC recruitment towards HCC. However, its ability to increase MSC migration to HCC for therapeutic purposes merits further evaluation.

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.

Bone formation in rabbit's leg muscle after autologous transplantation of bone marrow-derived mesenchymal stem cells expressing human bone morphogenic protein-2

BACKGROUND

To test whether autologous transplantation of bone marrow-derived mesenchymal stem cells (BM-MSCs) expressing human bone morphogenic protein-2 (hBMP-2) can produce bone in rabbit leg muscles.

MATERIALS AND METHODS

MSCs were isolated from BM of the iliac crest of rabbits and then infected with lentiviral vectors (LVs) bearing hBMP-2 and green fluorescent protein under the control of the cytomegalovirus (immediate early promoter). Differentiation of transduced MSCs to osteoblasts in vitro was evaluated with an alkaline phosphatase activity assay and immuohistochemistry against osteoblast specific markers. MSCs expressing hBMP-2 were placed in an absorbable gelatin sponge, which was then transplanted into the gastrocnemius of rabbits from which MSCs were isolated. Bone formation was examined by X-ray and histological analysis.

RESULTS

LVs efficiently mediated hBMP-2 gene expression in rabbit BM-MSCs. Ectopic expression of hBMP in these MSCs induced osteoblastic differentiation in vitro. Bone was formed after the MSCs expressing hBMP-2 were transplanted into rabbit muscles.

CONCLUSION

Ectopic expression of hBMP-2 in rabbit MSCs induces them to differentiate into osteoblasts in vitro and to form a bone in vivo.

Analysis of chemotactic molecules in bone marrow-derived mesenchymal stem cells and the skin: Ccl27-Ccr10 axis as a basis for targeting to cutaneous tissues

BACKGROUND AIMS

Adult stem cells produce a plethora of extracellular matrix molecules and have a high potential as cell-based therapeutics for connective tissue disorders of the skin. However, the primary challenge of the stem cell-based approach is associated with the inefficient homing of systemically infused stem cells to the skin.

METHODS

We examined chemotactic mechanisms that govern directional migration of mesenchymal stem cells (MSCs) into the skin by conducting a comprehensive expression analysis of chemotactic molecules in MSCs and defined cutaneous tissues from normal and hereditary epidermolysis bullosa (EB)-affected skin.

RESULTS

Analysis of chemokine receptors in short-term and long-term MSC cultures showed tissue culture-dependent expression of several receptors. Assessment of epidermis-derived and dermis-derived chemokines showed that most chemotactic signals that originate from the skin preferentially recruit different sets of leukocytes rather than MSCs. Analysis of the chemotactic molecules derived from EB-affected non-blistered skin showed only minor changes in expression of selected chemokines and receptors. Nevertheless, the data allowed us to define the Ccl27-Ccr10 chemotactic axis as the most potent for the recruitment of MSCs to the skin. Our in vivo analysis demonstrated that uniform expression of Ccr10 on MSCs and alteration of Ccl27 level in the skin enhance extravasation of stem cells from circulation and facilitate their migration within cutaneous tissue.

CONCLUSIONS

Collectively, our study provides a comprehensive analysis of chemotactic signals in normal and EB-affected skin and proof-of-concept data demonstrating that alteration of the chemotactic pathways can enhance skin homing of the therapeutic stem cells.

Identification of fibronectin as a major factor in human serum to recruit subchondral mesenchymal progenitor cells

Human serum has the potential for mesenchymal progenitor cell recruitment in repair of articular cartilage lesions. It is unclear which factor(s) in serum mediate this migratory effect. Our goal was to identify cell recruiting factors in human serum fractions obtained by ion exchange chromatography. The recruiting activity of serum fractions on human subchondral mesenchymal progenitor cells was analyzed using 96-well chemotaxis assays. Protein composition of recruiting serum fractions were analyzed by mass spectrometry and showed 58 potential candidates. Fibronectin, gelsolin, lumican, thrombospondin-1 and WNT-9a were identified as key candidates for progenitor cell recruitment. Only human plasma derived and recombinant fibronectin showed significant recruiting activity on progenitors reaching 50-90% of the recruiting activity of normal human serum. Presence of fibronectin in all human serum fractions with recruiting activity was verified by Western blot analysis. This study shows that fibronectin is a key factor in human serum to recruit mesenchymal progenitor cells and might be involved in subchondral mesenchymal progenitor cell migration into cartilage defects after microfracture.

The chemokines CXCL10 and XCL1 recruit human annulus fibrosus cells

STUDY DESIGN

Human annulus fibrosus tissue and cells were analyzed for the presence of chemokine receptors and the migratory effect of selected chemokines.

OBJECTIVE

To investigate spontaneous repair mechanisms and underlying cell recruitment in response to annular tears and degenerative defects.

SUMMARY OF BACKGROUND DATA

Resorption of herniated disc tissue and the attempt to close annulus tears with repair tissue occur spontaneously. Although chemokines are suggested to play a role in resorption of herniated disc tissue, the role of chemokines in annulus fibrosus homeostasis and repair remains unclear.

METHODS

Cells were isolated from annulus fibrosus tissue and expanded in the presence of human serum. Multiwell chemotaxis assays were used to analyze the migratory effect of human serum and 0 to 1000 nM concentrations of the chemokines CXCL7, CXCL10, CXCL12, CCL25, and XCL1 on annulus fibrosus cells (AFCs) (n = 9 per chemokine and dose). Presence of corresponding chemokine receptors in AFCs was determined by real-time polymerase chain reaction analysis and immunohistochemistry.

RESULTS

Serum (0.1%-10%) significantly (P < 0.01) stimulates the migration of AFCs. Compared with untreated cells, the migration of cells was significantly (P < 0.01) enhanced upon stimulation with 100 to 1000 nM CXCL10 and 1000 nM XCL1. Chemokine receptors showed low expression levels in expanded AFCs as assessed by polymerase chain reaction. Immunohistochemical staining of the CXCL10 receptor CXCR3 and the XCL1 receptor XCR1 showed that the presence of the particular receptors in AFCs expanded under conventional cell culture conditions. In native annulus fibrosus tissue, CXCR3 was evident, whereas XCR1 could not be detected.

CONCLUSION

The findings suggest that chemokines, in particular CXCL10, effectively recruit isolated AFCs. This suggests that chemokines are involved in annulus fibrosus homeostasis and potentially in spontaneous annulus repair attempts. This might have important implications for biological annulus-sealing strategies.

Chondrogenic differentiation of human mesenchymal stem cells in micro-masses is impaired by high doses of the chemokine CXCL7

Chemokines have been shown to recruit human mesenchymal stem cells (MSCs) and are suggested to be promising candidates for in situ tissue engineering. The aim of our study was to analyse the effect of CXCL7, a chemokine that has the capacity to recruit MSCs, on the chondrogenic differentiation of MSCs. Bone marrow-derived MSCs were cultured in high-density micro-masses under serum-free conditions and were co-stimulated with 0-100 nM CXCL7 in the presence of 10 ng/ml transforming growth factor-β3 (TGFβ3). Micro-masses stimulated without growth factors and chemokines served as controls. Histological staining of proteoglycan, immunostaining of type II collagen, staining of mineralized matrix according to von Kossa as well as real-time gene expression analysis of typical chondrogenic and osteogenic marker genes showed that the TGFβ3-mediated chondrogenic development of MSCs was not impaired by 0-50 nM CXCL7. Micro-masses stimulated with TGFβ3 and CXCL7 developed chondrogenic cells and formed a cartilaginous matrix rich in proteoglycans, accompanied by the induction of typical chondrogenic marker genes, such as cartilage oligomeric matrix protein, aggrecan, type IIα1 collagen and by regulation of matrix metalloproteinases and their inhibitors. As assessed by histological staining, MSCs showed a significantly reduced deposition of proteoglycan and a mildly mineralized matrix when stimulated with TGFβ3 in the presence of 100 nM CXCL7. Induction of osteogenic marker genes such as osteocalcin was not evident. These results suggest that low doses of CXCL7 do not impair the chondrogenic differentiation of bone marrow-derived stem cells and may suited for in situ cartilage tissue engineering.

Nuclear receptors Nur77 and Nurr1 modulate mesenchymal stromal cell migration

Detailed understanding of mesenchymal stromal cells (MSC) migration is imperative for future cellular therapies. To identify genes involved in the process of MSC migration, we generated gene expression profiles of migrating and nonmigrating fetal bone marrow MSC (FBMSC). Only 12 genes showed differential expression in migrating versus nonmigrating FBMSC. The nuclear receptors Nur77 and Nurr1 showed the highest expression in migratory MSC. Nur77 and Nurr1 are members of NR4A nuclear orphan receptor family, and we found that their expression is rapidly increased upon exposure of FBMSC to the migratory stimuli stromal-derived factor-1α (SDF-1α) and platelet-derived growth factor-BB. Lentiviral expression of Nur77 or Nurr1 resulted in enhanced migration of FBMSC toward SDF-1α compared with mock-transduced FBMSC. Analysis of the cell cycle, known to be involved in MSC migration, revealed that expression of Nur77 and Nurr1 decreases the proportion of cells in S-phase compared with control cells. Further, gain-of-function experiments showed increased hepatocyte growth factor expression and interleukin (IL)-6 and IL-8 production in MSC. Despite the altered cytokine profile, FBMSC expressing Nur77 or Nurr1 maintained the capacity to inhibit T-cell proliferation in a mixed lymphocyte reaction. Our results demonstrate that Nur77 and Nurr1 promote FBMSC migration. Modulation of Nur77 and Nurr1 activity may therefore offer perspectives to enhance the migratory potential of FBMSC which may specifically regulate the local immune response.

Breast cancer stem cells are regulated by mesenchymal stem cells through cytokine networks

We have used in vitro and mouse xenograft models to examine the interaction between breast cancer stem cells (CSC) and bone marrow-derived mesenchymal stem cells (MSC). We show that both of these cell populations are organized in a cellular hierarchy in which primitive aldehyde dehydrogenase expressing mesenchymal cells regulate breast CSCs through cytokine loops involving IL6 and CXCL7. In NOD/SCID mice, labeled MSCs introduced into the tibia traffic to sites of growing breast tumor xenografts where they accelerated tumor growth by increasing the breast CSC population. With immunochemistry, we identified MSC-CSC niches in these tumor xenografts as well as in frozen sections from primary human breast cancers. Bone marrow-derived MSCs may accelerate human breast tumor growth by generating cytokine networks that regulate the CSC population.

Chemokine profile of synovial fluid from normal, osteoarthritis and rheumatoid arthritis patients: CCL25, CXCL10 and XCL1 recruit human subchondral mesenchymal progenitor cells

OBJECTIVE

The microfracture technique activates mesenchymal progenitors that enter the cartilage defect and form cartilage repair tissue. Synovial fluid (SF) has been shown to stimulate the migration of subchondral progenitors. The aim of our study was to determine the chemokine profile of SF from normal, rheumatoid arthritis (RA) and osteoarthritis (OA) donors and evaluate the chemotactic effect of selected chemokines on human subchondral progenitor cells.

METHOD

Chemokine levels of SF were analyzed using human chemokine antibody membrane arrays. The chemotactic potential of selected chemokines on human mesenchymal progenitors derived from subchondral cortico-spongious bone was tested using 96-well chemotaxis assays. Chemokine receptor expression of subchondral progenitors was assessed by real-time gene expression analysis and immuno-histochemistry.

RESULTS

Chemokine antibody array analysis showed that SF contains a broad range of chemokines. Ten chemokines that showed significantly reduced levels in RA or OA compared to normal SF or robustly high levels in all SF tested were used for further chemotactic analysis. Chemotaxis assays showed that the chemokines MDC/CCL22, CTACK/CCL27, ENA78/CXCL5 and SDF1α/CXCL12 significantly inhibited migration of progenitors, while TECK/CCL25, IP10/CXCL10 and Lymphotactin/XCL1 effectively stimulated cell migration. MCP1/CCL2, Eotaxin2/CCL24 and NAP2/CXCL7 showed no chemotactic effect on subchondral progenitors. Gene expression and immuno-histochemical analysis of corresponding chemokine receptors document presence of low levels of chemokine receptors in subchondral progenitors, with the CXCL10 receptor CXCR3 showing the highest expression level.

CONCLUSION

These results suggest that SF contains chemokines that may contribute to the recruitment of human mesenchymal progenitors from the subchondral bone in microfracture.

Comparative analysis of chemokine receptor's expression in mesenchymal stem cells derived from human bone marrow and adipose tissue

Mesenchymal stem cells (MSCs) are considered as promising candidates for new clinical trials of cell therapies. Bone marrow (BM) was the first source reported to contain MSCs; however, using it may be detrimental due to the highly invasive aspiration procedures. More recently, adipose tissue, attainable by a less invasive method, has been introduced as an alternative source of MSCs. So far, MSCs derived from these two sources have been compared in different characters; however, one of the main properties, i.e., the expression of chemokine receptors, has been ignored in these comparisons. In the present study, human MSCs were derived from bone marrow and adipose tissues and characterized by their expression of some cell surface antigens and also differentiation capacity. The expression of five selected chemokine receptors, which seems to be important in cell homing, was also compared. Semiquantitative reverse transcription-polymerase chain reaction method was used to assess gene expression levels of these chemokine receptors. Our results indicate that expression of these receptors in human MSCs, derived from adipose tissue, was higher than MSCs from bone marrow. Chemokine receptors and their ligands and adhesion molecules play an important role in tissue-specific homing of leukocytes and have also been implicated in trafficking of hematopoietic precursors into and through tissues. Therefore, MSCs from adipose tissue may show a better migration and homing capacity and they might be a better candidate for therapeutic purposes.

Genomic phenotype of non-cultured pulmonary fibroblasts in idiopathic pulmonary fibrosis

Activated fibroblasts are the central effector cells of the progressive fibrotic process in idiopathic pulmonary fibrosis (IPF). Characterizing the genomic phenotype of isolated fibroblasts is essential to understanding IPF pathogenesis. Comparing the genomic phenotype of non-cultured pulmonary fibroblasts from advanced IPF patients' and normal lungs revealed novel genes, biological processes and concomitant pathways previously unreported in IPF fibroblasts. We demonstrate altered expression in proteasomal constituents, ubiquitination-mediators, Wnt, apoptosis and vitamin metabolic pathways and cell cycle regulators, suggestive of loss of cellular homeostasis. Specifically, FBXO32, CXCL14, BDKRB1 and NMNAT1 were up-regulated, while RARA and CDKN2D were down-regulated. Paradoxically, pro-apoptotic inducers TNFSF10, BAX and CASP6 were also found to be increased. This comprehensive description of altered gene expression in isolated IPF fibroblasts underscores the complex biological processes characteristic of IPF and may provide a foundation for future research into this devastating disease.

Chemokine profile of human serum from whole blood: migratory effects of CXCL-10 and CXCL-11 on human mesenchymal stem cells

Autologous human serum is used in cartilage repair and may exert its effect by the recruitment of mesenchymal stem and progenitor cells (MSC). Aim of our study was to analyze the chemokine profile of human serum and to verify chemotactic activity of selected chemokines on MSC. Human MSC were isolated from iliac crest bone marrow aspirates. Chemotactic activity of human serum made from whole blood and pharma grade serum was tested in 96-well chemotaxis assays and chemokine levels were analyzed using human chemokine antibody membrane arrays. The chemotactic potential of selected chemokines on MSC was tested dose dependently using chemotaxis assays. Human serum derived from whole blood significantly attracted human MSC, while pharma grade serum did not recruit MSC. Human chemokine antibody array analysis showed that the level of chemokines CXCL-3, 5, 7-8, 10-12, 16; CCL- 2, 5, 11, 13, 16-20, 24-25, 27; as well as XCL-1 was elevated (fold change >1.5) in serum derived from whole blood compared to nonrecruiting pharma grade serum. Chemotaxis assays showed that the chemokines IP-10/CXCL-10 and I-TAC/CXCL-11 significantly recruit human MSC. PARC/CCL-18, HCC-4/CCL-16, CTACK/CCL-27, and Lymphotactin/XCL-1 showed no chemotactic effect on MSC. Therefore, human serum derived from whole blood contains chemokines that may contribute to serum-mediated recruitment of human mesenchymal progenitors from bone marrow.

Matrix metalloproteinase 1 is necessary for the migration of human bone marrow-derived mesenchymal stem cells toward human glioma

Human mesenchymal stem cells (MSCs) have increasingly been used as cellular vectors for the delivery of therapeutic genes to tumors. However, the precise mechanism of mobilization remains poorly defined. In this study, MSCs that expressed similar cell surface markers and exhibited multilineage differentiation potentials were isolated from various donors. Interestingly, different MSC isolates displayed differential migration ability toward human glioma cells. We hypothesized that distinct molecular signals may be involved in the varied tumor tropisms exhibited by different MSC isolates. To test this hypothesis, gene expression profiles of tumor-trophic MSCs were compared with those of non–tumor-trophic MSCs. Among the various differentially regulated genes, matrix metalloproteinase one (MMP1) gene expression and its protein activities were enhanced by 27-fold and 21-fold, respectively, in highly migrating MSCs compared with poorly migrating MSCs. By contrast, there was no change in the transcriptional levels of other MMPs. Functional inactivation of MMP1 abrogated the migratory potential of MSCs toward glioma-conditioned medium. Conversely, the nonmigratory phenotype of poorly migrating MSC could be rescued in the presence of either recombinant MMP1 or conditioned medium from the highly migrating MSCs. Ectopic expression of MMP1 in these poorly migrating cells also rendered the cells responsive to the signaling cues from the glioma cells in vivo. However, blocking the interaction of MMP1 and its cognate receptor PAR1 effectively diminished the migratory ability of MSCs. Taken together, this study provides, for the first time, supporting evidence that MMP1 is critically involved in the migration capacity of MSCs, acting through the MMP1/PAR1 axis. Stem Cells 2009;27:1366–1375

Gene expression profiling of human mesenchymal stem cells chemotactically induced with CXCL12

In situ tissue engineering is a promising approach in regenerative medicine, with the possibility that adult stem or progenitor cells will be guided chemotactically to a tissue defect and subsequently differentiate into the surrounding tissue type. Mesenchymal stem cells (MSC) represent attractive candidate cells. Chemokines such as CXCL12 (SDF-1alpha) chemoattract MSC, but little is known about the molecular processes involved in the chemotaxis and migration of MSC. In this study, MSC recruitment by CXCL12 was investigated by genome-wide microarray analysis. The dose-dependent migration potential of bone-marrow-derived MSC toward CXCL12 was measured in an in vitro assay, with a maximum being recorded at a concentration of 1,000 nM CXCL12. Microarray analysis of MSC stimulated with CXCL12 and non-stimulated controls showed 30 differentially expressed genes (24 induced and six repressed). Pathway analysis revealed 11 differentially expressed genes involved in cellular movement and cytokine-cytokine receptor interaction, including those for migratory inducers such as the chemokines CXCL8 and CCL26, the leukocyte inhibitory factor, secretogranin II, and prostaglandin endoperoxide synthase 2. These results were confirmed by real-time polymerase chain reaction for selected genes. The obtained data provide further insights into the molecular mechanisms involved in chemotactic processes in cell migration and designate CXCL12 as a promising candidate for in situ recruitment in regenerative therapies.