Adhesion Of Progenitor Cells Research Articles

Senolysis potentiates endothelial progenitor cell adhesion to and integration into the brain vasculature

Abstract Background One of the most severe consequences of ageing is cognitive decline, which is associated with dysfunction of the brain microvasculature. Thus, repairing the brain vasculature could result in healthier brain function. Methods To better understand the potential beneficial effect of endothelial progenitor cells (EPCs) in vascular repair, we studied the adhesion and integration of EPCs using the early embryonic mouse aorta–gonad–mesonephros – MAgEC 10.5 endothelial cell line. The EPC interaction with brain microvasculature was monitored ex vivo and in vivo using epifluorescence, laser confocal and two-photon microscopy in healthy young and old animals. The effects of senolysis, EPC activation and ischaemia (two-vessel occlusion model) were analysed in BALB/c and FVB/Ant: TgCAG-yfp_sb #27 mice. Results MAgEC 10.5 cells rapidly adhered to brain microvasculature and some differentiated into mature endothelial cells (ECs). MAgEC 10.5-derived endothelial cells integrated into microvessels, established tight junctions and co-formed vessel lumens with pre-existing ECs within five days. Adhesion and integration were much weaker in aged mice, but were increased by depleting senescent cells using abt-263 or dasatinib plus quercetin. Furthermore, MAgEC 10.5 cell adhesion to and integration into brain vessels were increased by ischaemia and by pre-activating EPCs with TNFα. Conclusions Combining progenitor cell therapy with senolytic therapy and the prior activation of EPCs are promising for improving EPC adhesion to and integration into the cerebral vasculature and could help rejuvenate the ageing brain.

The effect of augmenting suture material with magnesium and platelet-rich plasma on the in vitro adhesion and proliferation potential of subacromial bursa-derived progenitor cells

Connective tissue subacromial bursa-derived progenitor cells (SBDCs) have been suggested as a potent biologic augment to promote healing of the repaired rotator cuff tendon. Maximizing the amount of retained progenitor cells at the tendon repair site is essential for ensuring an optimal healing environment, warranting a search for proadhesive and proliferative adjuvants. The purpose was to evaluate the effect of magnesium (Mg), platelet-rich plasma (PRP), and a combination of both adjuvants on the invitro cellular adhesion and proliferation potential of SBDCs on suture material commonly used in rotator cuff surgery. SBDCs were isolated from subacromial bursa samples harvested during rotator cuff repair and cultured in growth media. Commercially available collagen-coated nonabsorbable flat-braided suture was cut into 1-inch pieces, placed into 48-well culture dishes, and sterilized under ultraviolet light. Either a one-time dose of 5 mM sterile Mg, 0.2 mL of PRP, or a combination of both adjuvants was added, while a group without treatment served as a negative control. Cellular proliferation and adhesion assays on suture material were performed for each treatment condition. Augmenting the suture with Mg resulted in a significantly increased cellular adhesion (total number of attached cells) of SBDCs compared to PRP alone (31,527±19,884 vs. 13,619±8808; P<.001), no treatment (31,527±19,884 vs. 21,643±8194; P=.016), and combination of both adjuvants (31,527±19,884 vs. 17,121±11,935; P<.001). Further, augmentation with Mg achieved a significant increase in cellular proliferation (absorbance) of SBDCs on suture material when compared to the PRP (0.516±0.207 vs. 0.424±0.131; P=.001) and no treatment (0.516±0.207 vs. 0.383±0.094; P<.001) group. The combination of Mg and PRP showed a significantly higher proliferation potential compared to PRP alone (0.512±0.194 vs. 0.424±0.131; P=.001) and no treatment (0.512±0.194 vs. 0.383±0.094; P<.001). There were no significant differences in the remaining intergroup comparisons (P>.05, respectively). Augmenting suture material with Mg resulted in a significantly increased cellular adhesion of SBDCs compared to untreated suture material, as well as augmentation with PRP alone or a combination of both adjuvants. Further, Mg with or without PRP augmentation achieved a significant increase in the cellular proliferation of SBDCs on suture material compared to untreated sutures and augmentation with PRP alone. Application of Mg may be a clinically feasible approach to optimizing the use of SBDCs as a biological augment in rotator cuff repair, while combined augmentation with PRP may harness the full potential for optimized tissue recovery due to the high concentration of PRP-derived growth factors.

Physical biomarkers for human hematopoietic stem and progenitor cells

Adhesion of hematopoietic stem and progenitor cells (HSPCs) to the bone marrow niche plays critical roles in the maintenance of the most primitive HSPCs. The interactions of HSPC−niche interactions are clinically relevant in acute myeloid leukemia (AML), because (i) leukemia-initiating cells adhered to the marrow niche are protected from the cytotoxic effect by chemotherapy and (ii) mobilization of HSPCs from healthy donors' bone marrow is crucial for the effective stem cell transplantation. However, although many clinical agents have been developed for the HSPC mobilization, the effects caused by the extrinsic molecular cues were traditionally evaluated based on phenomenological observations. This review highlights the recent interdisciplinary challenges of hematologists, biophysicists and cell biologists towards the design of defined in vitro niche models and the development of physical biomarkers for quantitative indexing of differential effects of clinical agents on human HSPCs.

Decellularized Scaffold-Based Artificial Vascular Patch for Porcine Vascular Repair.

Vascular transplantation is an effective strategy against cardiovascular diseases (CVD), and artificial vascular patches are of urgent need across the world. In this work, we designed a multifunctional decellularized scaffolds (DCS)-based vascular patch for porcine vascular repair. Ammonium phosphate zwitter-ion (APZI) and poly(vinyl alcohol) (PVA) hydrogel were coated on the surface of DCS to improve the mechanical properties and biocompatibility of an artificial vascular patch. Then a heparin (Hep)-loaded metal-organic framework (MOF) further decorated the artificial vascular patches to inhibit blood coagulation and promote vascular endothelialization. The obtained artificial vascular patch showed suitable mechanical properties, good biocompatibility, and blood compatibility. In addition, the proliferation and adhesion of endothelial progenitor cells (EPCs) on the surface of artificial vascular patch improved a lot when compared with unmodified PVA/DCS. According to the results of B-ultrasound and CT images, the artificial vascular patch could maintain the patency of the implant site after implanting into the pig carotid artery. The current results solidly support that a MOF-Hep/APZI-PVA/DCS vascular patch would be an excellent vascular replacement material.

Nitric oxide promotes cell-matrix adhesion of endothelial progenitor cells under hypoxia condition via ITGA5 CpG promoter demethylation

Hypoxia or low oxygen tension causes changes in the structure and functional phenotype of the endothelial progenitor cells (EPCs). EPCs are found to be involved in angiogenesis and vascular repair. However, EPC's role in cell-matrix adhesion under hypoxia conditions is not clearly established. Nitric oxide (NO) exerts a wide range of biological functions, especially in regulating the mobilization and vascular repair of EPCs. In contrast, the link between NO and its role in cell-matrix deadhesion under hypoxia is not studied yet. Here, we investigated the protective role of NO in hypoxia-induced cell-matrix deadhesion of EPCs through an epigenetic mechanism. The EPCs were exposed to 2% hypoxia in the presence or absence of 10 μM Spermine NONOate (NO donor). The result demonstrates that hypoxia exposure intensified mitochondrial oxidative damage and energy defects. Using miScript miRNA qPCR array-based screening, the study found miR-148 as a novel target of hypoxia-induced DNMT1 activation. Mechanistically, the study discovered that hypoxia suppressed miR-148 levels and stimulated EPCs cell-matrix deadhesion via increasing DNMT1 mediated Integrin alpha-5 (ITGA5) CpG promoter hypermethylation. Treatment with a mitochondria-targeted antioxidant, MitoTEMPO, or epigenetic DNMT inhibitor, 5′-azacitidine, or miR-148 overexpression in hypoxic EPCs culture, prevented the cell-matrix deadhesion compared to hypoxic EPCs. Further, treatment of spNO or transient expression of eNOS-GFP attenuated hypoxia-induced cell-matrix deadhesion via inhibition of ITGA5 CpG island promoter methylation. In conclusion, the study provides evidence that NO is essential for cell-matrix adhesion of EPCs by epigenetically mitigating ITGA5 CpG promoter hypermethylation under hypoxia conditions. This finding uncovers the previously undefined mechanism of NO-mediated diminution of hypoxia-induced cell-matrix deadhesion and dysfunction induced by low oxygen tension.

Infertile human endometrial organoid apical protein secretions are dysregulated and impair trophoblast progenitor cell adhesion.

Embryo implantation failure leads to infertility. As an important approach to regulate implantation, endometrial epithelial cells produce and secrete factors apically into the uterine cavity in the receptive phase to prepare the initial blastocyst adhesion and implantation. Organoids were recently developed from human endometrial epithelium with similar apical-basal polarity compared to endometrial gland making it an ideal model to study endometrial epithelial secretions. Endometrial organoids were established using endometrial biopsies from women with primary infertility and normal fertility. Fertile and infertile organoids were treated with hormones to model receptive phase of the endometrial epithelium and intra-organoid fluid (IOF) was collected to compare the apical protein secretion profile and function on trophoblast cell adhesion. Our data show that infertile organoids were dysregulated in their response to estrogen and progesterone treatment. Proteomic analysis of organoid apical secretions identified 150 dysregulated proteins between fertile and infertile groups (>1.5-fold change). Trophoblast progenitor spheroids (blastocyst surrogates) treated with infertile organoid apical secretions significantly compromised their adhesion to organoid epithelial cell monolayers compared to fertile group (P < 0.0001). This study revealed that endometrial organoid apical secretions alter trophoblast cell adhesiveness relative to fertility status of women. It paves the way to determine the molecular mechanisms by which endometrial epithelial apical released factors regulate blastocyst initial attachment and implantation.

In vitro evaluation of modified pericardium for cardiovascular applications

The growing prevalence of cardiovascular diseases is leading to an increase in required cardiovascular implants. Pericardial tissues have been used for bioprosthetic manufacture due to advantage in availability and excellent mechanical properties. Porcine pericardium is considered to be suitable for prosthetic fabrication. In this study, porcine pericardium was decellularized and cross linked with 0.05% glutaraldehyde. The modified pericardium was characterized by histology staining, FTIR, mechanical properties and suture retention. In vitro degradation of the modified pericardium was determined via the remaining dry weight and hydroxyproline assay after incubation in collagenase solution. The modified membrane was evaluated for in vitro cytotoxicity and supporting human endothelial progenitor cell attachment and proliferation. Trichrome staining and FTIR examination revealed the crosslinking effect of glutaraldehyde with more tight internal collagen fibers structure and slight shift of amide II group. In comparison to the decellularized sample, the modified membrane showed a strong mechanical and suture retention strength. Significant resistance to enzymatic digestion was also recorded. The modified pericardium did not cause toxicity to the fibroblast and supported an appropriate adhesion and proliferation of human endothelial progenitor cells. These results indicated that the modified pericardium could be utilized as a potential natural scaffold for cardiovascular applications.

Bone Quantification Around Chitosan-Coated Titanium Dental Implants: A Preliminary Study by Micro-CT Analysis in Jaw of a Canine Model.

Surface treatments of Ti in the dental implant industry are performed with the aim of in-creasing its bioactivity and osseointegration capacity. Chitosan (Cht) is a polysaccharide that has been proposed as a promising biomaterial in tissue engineering and bone regeneration, due to its ability to stimulate the recruitment and adhesion of osteogenic progenitor cells. The aim of our preliminary study was to evaluate, by micro-computed tomography (micro-CT), the osseointegration and bone formation around Cht-coated implants and to compare them with conventional surface-etched implants (SLA type). Four im-plants (8.5 mm length × 3.5 mm Ø) per hemiarch, were inserted into the jaws of five dogs, divided into two groups: chitosan-coated implant group (ChtG) and control group (CG). Twelve weeks after surgery, euthanasia was performed, and sectioned bone blocks were obtained and scanned by micro-CT and two bone parameters were measured: bone in contact with the implant surface (BCIS) and peri-implant bone area (PIBA). For BCIS and PIBA statistically significant values were obtained for the ChtG group with respect to CG (p = 0.005; p = 0.014 and p < 0.001 and p = 0.002, respectively). The results, despite the limitations, demonstrated the usefulness of chitosan coatings. However, studies with larger sample sizes and adequate experimental models would be necessary to confirm the results.

In vivo biocompatibility analysis of the recellularized canine tracheal scaffolds with canine epithelial and endothelial progenitor cells

ABSTRACT Decellularized extracellular matrix (ECM) has frequently been applied as a biomaterial for tissue engineering purposes. When implanted, their role can be essential for partial trachea replacement in patients that require a viable transplant solution. Acellular canine tracheal scaffolds with preserved ECM structure, flexibility, and proteins were obtained by high pressure vacuum decellularization. Here, we aimed to evaluate the cell adhesion and proliferation of canine tracheal epithelial cells (EpC) and canine yolk sac endothelial progenitor cells (YS) cultivated on canine decellularized tracheal scaffolds and test the in vivo biocompatibility of these recellularized scaffolds implanted in BALB-c nude mice. In order to evaluate the recellularization efficiency, scaffolds were evaluated by scanning electron microscopy (SEM), immunofluorescence, DNA quantification, mycoplasma test, and in vivo biocompatibility. The scaffolds sterility was confirmed, and EpC and YS cells were cultured by 7 and 14 days. We demonstrated by SEM, immunofluorescence, and genomic DNA analyzes cell adhesion to tracheal ECM. Then, recellularized scaffolds were in vivo subcutaneously implanted in mice and after 45 days, the fragments were collected and analyzed by Hematoxylin-Eosin and Gömori Trichrome staining and PCNA, CD4, CD8, and CD68 immunohistochemistry. In vivo results confirmed that the implanted tissue remains preserved and proliferative, and no fibrotic tissue process was observed in animals. Finally, our results showed the recellularization success due the preserved ECM proteins, and that these may be suitable to future preclinical studies applications for partial trachea replacement in tissue engineering.

Decellularized scaffold-based poly(ethylene glycol) biomimetic vascular patches modified with polyelectrolyte multilayer of heparin and chitosan: preparation and vascular tissue engineering applications in a porcine model.

Mechanical property mismatch between vascular patches and native blood vessels can result in post-operation failure; therefore, vascular patches that mimic the biomechanical properties of native blood vessels must be developed. In this study, we constructed a biomimetic vascular patch by coating a poly(ethylene glycol) (PEG) film onto a decellularized scaffold (DCS) and modifying its surface with a heparin-chitosan polyelectrolyte multilayer (PEM). The PEM-modified PEG/DCS vascular patches exhibited comparable mechanical characteristics with native blood vessels. They effectively resisted platelet adhesion, reduced the hemolysis rate, increased the clotting time in vitro, and favoured the adhesion and growth of endothelial progenitor cells. In addition, the modified patches maintained long-term patency (5 months) of the treated arteries in vivo. Because of the synergistic effect of heparin and chitosan in PEM, the vascular patches may be able to manage medical complications. Thus, the PEM-modified PEG/DCS vascular patches may have promising applications in the repair of damaged or diseased blood vessels.

PCDH19 interplay with GABA(A) receptors: a window to DEE9 pathogenetic mechanisms.

PCDH19 interplay with GABA(A) receptors: a window to DEE9 pathogenetic mechanisms.

Three-Dimensional Modeling of the Structural Microenvironment in Post-Traumatic War Wounds

BACKGROUND:The development of post-traumatic heterotopic ossification (HO) is a common, undesirable sequela in patients with high-energy (war-related) extremity injuries. While inflammatory and osteoinductive signaling pathways are known to be involved in the development and progression of post-traumatic HO, features of the structural microenvironment within which the ectopic bone begins to form remain poorly understood. Thus, increasing our knowledge of molecular and structural changes within the healing wound may help elucidate the pathogenesis of post-traumatic HO and aid in the development of specific treatment and/or prevention strategies.METHODS:In this study, we performed high-resolution microscopy and biochemical analysis of tissues obtained from traumatic war wounds to characterize changes in the structural microenvironment. In addition, using an electrospinning approach, we modeled this microenvironment to reconstitute a three-dimensional type I collagen scaffold with non-woven, randomly oriented nanofibers where we evaluated the performance of primary mesenchymal progenitor cells.RESULTS:We found that traumatic war wounds are characterized by a disorganized, densely fibrotic collagen I matrix that influences progenitor cells adhesion, proliferation and osteogenic differentiation potential.CONCLUSION:Altogether, these results suggest that the structural microenvironment present in traumatic war wounds has the potential to contribute to the development of post-traumatic HO. Our findings may support novel treatment strategies directed towards modifying the structural microenvironment after traumatic injury.

Laminin 332 Is Indispensable for Homeostatic Epidermal Differentiation Programs

The skin epidermis is attached to the underlying dermis by a laminin 332 (Lm332)-rich basement membrane. Consequently, loss of Lm332 leads to the severe blistering disorder epidermolysis bullosa junctionalis in humans and animals. Owing to the indispensable role of Lm332 in keratinocyte adhesion invivo, the severity of the disease has limited research into other functions of the protein. We have conditionally disrupted Lm332 expression in basal keratinocytes of adult mice. Although blisters develop along the interfollicular epidermis, hair follicle basal cells provide sufficient anchorage of the epidermis to the dermis, making inducible deletion of the Lama3 gene compatible with life. Loss of Lm332 promoted the thickening of the epidermis and exaggerated desquamation. Global RNA expression analysis revealed major changes in the expression of keratins, cornified envelope proteins, and cellular stress markers. These modifications of the keratinocyte genetic program are accompanied by changes in cell shape and disorganization of the actin cytoskeleton. These data indicate that loss of Lm332-mediated progenitor cell adhesion alters cell fate and disturbs epidermal homeostasis.

Development of Biomimetic Alginate/Gelatin/Elastin Sponges with Recognition Properties toward Bioactive Peptides for Cardiac Tissue Engineering.

In recent years, there has been an increasing interest toward the covalent binding of bioactive peptides from extracellular matrix proteins on scaffolds as a promising functionalization strategy in the development of biomimetic matrices for tissue engineering. A totally new approach for scaffold functionalization with peptides is based on Molecular Imprinting technology. In this work, imprinted particles with recognition properties toward laminin and fibronectin bioactive moieties were synthetized and used for the functionalization of biomimetic sponges, which were based on a blend of alginate, gelatin, and elastin. Functionalized sponges underwent a complete morphological, physicochemical, mechanical, functional, and biological characterization. Micrographs of functionalized sponges showed a highly porous structure and a quite homogeneous distribution of imprinted particles on their surface. Infrared and thermal analyses pointed out the presence of interactions between blend components. Biodegradation and mechanical properties appeared adequate for the aimed application. The results of recognition tests showed that the deposition on sponges did not alter the specific recognition and binding behavior of imprinted particles. In vitro biological characterization with cardiac progenitor cells showed that early cell adherence was promoted. In vivo analysis showed that developed scaffolds improved cardiac progenitor cell adhesion and differentiation toward myocardial phenotypes.

Antibody CD133 Biofunctionalization of Ammonium Acryloyldimethyltaurate and Vinylpyrrolidone Co-Polymer-Based Coating of the Vascular Implants.

Current vascular stents, such as drug eluting stents (DES), have some serious drawbacks, like in stent restenosis and thrombosis. Therefore, other solutions are sought to overcome these post-implantations complications. These include the strategy of biofunctionalization of the stent surface with antibodies that facilitate adhesion of endothelial cells (ECs) or endothelial progenitor cells (EPCs). Rapid re-endothelialization of the surface minimizes the risk of possible complications. In this study, we proposed ammonium acryloyldimethyltaurate/vinylpyrrolidone co-polymer-based surface (AVC), which was mercaptosilanized in order to expose free thiol groups. The presence of free thiol groups allowed for the covalent attachment of CD133 antibodies by disulfide bridges formation between mercaptosilanized surface and cysteine of the protein molecule thiol groups. Various examinations were performed in order to validate the procedure, including attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR) and Fourier transform Raman spectroscopy (FT-Raman), atomic force microscopy (AFM) and scanning electron microscopy (SEM). By means of ATR-FTIR spectroscopy presence of the CD133 antibody within coating was confirmed. In vitro studies proved good biocompatibility for blood cells without induction of hemolytic response. Thus, proposed biofunctionalized CD133 antibody AVC surface has shown sufficient stability for adapting as cardiovascular implant coating and biocompatibility. According to conducted in vitro studies, the modified surface can be further tested for applications in various biological systems.

Chemerin enhances the adhesion and migration of human endothelial progenitor cells and increases lipid accumulation in mice with atherosclerosis

BackgroundThe role of adipokines in the development of atherosclerosis (AS) has received increasing attention in recent years. This study aimed to explore the effects of chemerin on the functions of human endothelial progenitor cells (EPCs) and to investigate its role in lipid accumulation in ApoE-knockout (ApoE−/−) mice.MethodsEPCs were cultured and treated with chemerin together with the specific p38 mitogen-activated protein kinase (MAPK) inhibitor SB 203580 in a time- and dose-dependent manner. Changes in migration, adhesion, proliferation and the apoptosis rate of EPCs were detected. ApoE−/− mice with high-fat diet-induced AS were treated with chemerin with or without SB 203580. Weights were recorded, lipid indicators were detected, and tissues sections were stained.ResultsThe data showed that chemerin enhanced the adhesion and migration abilities of EPCs, and reduced the apoptosis ratio and that this effect might be mediated through the p38 MAPK pathway. Additionally, chemerin increased the instability of plaques. Compared with the control group and the inhibitor group, ApoE−/− mice treated with chemerin protein had more serious arterial stenosis, higher lipid contents in plaques and decreased collagen. Lipid accumulation in the liver and kidney and inflammation in the hepatic portal area were enhanced by treatment with chemerin, and the size of adipocytes also increased after chemerin treatment. In conclusion, chemerin can enhance the adhesion and migration abilities of human EPCs and reduce the apoptosis ratio. In animals, chemerin can increase lipid accumulation in atherosclerotic plaques and exacerbate plaques instability. At the same time, chemerin can cause abnormal lipid accumulation in the livers and kidneys of model animals. After specifically blocking the p38 MAPK pathway, the effect of chemerin was reduced.ConclusionsIn conclusion, this study showed that chemerin enhances the adhesion and migration abilities of EPCs and increases the instability of plaques and abnormal lipid accumulation in ApoE−/− mice. Furthermore, these effects might be mediated through the p38 MAPK pathway.

IGF-1 loaded injectable microspheres for potential repair of the infarcted myocardium.

The use of injectable scaffolds to repair the infarcted heart is receiving great interest. Thermosensitive polymers, in situ polymerization, in situ cross-linking, and self-assembling peptides are the most investigated approaches to obtain injectability.Aim of the present work was the preparation and characterization of a novel bioactive scaffold, in form of injectable microspheres, for cardiac repair. Gellan/gelatin microspheres were prepared by a water-in-oil emulsion and loaded by adsorption with Insulin-like growth factor 1 to promote tissue regeneration. Obtained microspheres underwent morphological, physicochemical and biological characterization, including cell culture tests in static and dynamic conditions and in vivo tests. Morphological analysis of the microspheres showed a spherical shape, a microporous surface and an average diameter of 66 ± 17µm (under dry conditions) and 123 ± 24 µm (under wet conditions). Chemical Imaging analysis pointed out a homogeneous distribution of gellan, gelatin and Insulin-like growth factor-1 within the microsphere matrix. In vitro cell culture tests showed that the microspheres promoted rat cardiac progenitor cells adhesion, and cluster formation. After dynamic suspension culture within an impeller-free bioreactor, cells still adhered to microspheres, spreading their cytoplasm over microsphere surface. Intramyocardial administration of microspheres in a cryoinjury rat model attenuated chamber dilatation, myocardial damage and fibrosis and improved cell homing.Overall, the findings of this study confirm that the produced microspheres display morphological, physicochemical, functional and biological properties potentially adequate for future applications as injectable scaffold for cardiac tissue engineering.

CD44 engagement enhances acute myeloid leukemia cell adhesion to the bone marrow microenvironment by increasing VLA-4 avidity.

Adhesive properties of leukemia cells shape the degree of organ infiltration and the extent of leukocytosis. CD44 and the integrin VLA-4, a CD49d/CD29 heterodimer, are important factors in progenitor cell adhesion in bone marrow. Here, we report their cooperation in acute myeloid leukemia (AML) by a novel non-classical CD44-mediated way of inside-out VLA-4 activation. In primary AML bone marrow samples from patients and the OCI-AML3 cell line, CD44 engagement by hyaluronan induced inside-out activation of VLA-4 resulting in enhanced leukemia cell adhesion on VCAM-1. This was independent of VLA-4 affinity regulation but based on ligand-induced integrin clustering on the cell surface. CD44-induced VLA-4 activation could be inhibited by the Src family kinase inhibitor PP2 and the multikinase inhibitor midostaurin. As a further consequence, the increased adhesion on VCAM-1 allowed AML cells to bind stromal cells strongly. Thereby, the VLA-4/VCAM-1 interaction promoted activation of Akt, MAPK, NF-kB and mTOR signaling and decreased AML cell apoptosis. Collectively, our investigations provide a mechanistic description of an unusual CD44 function in regulating VLA-4 avidity in AML, enhancing AML cell retention in the supportive bone marrow microenvironment.

PGC-1α gene transfer restores adhesion and reendothelialization of endothelial progenitor cells from patients with hypertension.

Endothelial progenitor cells (EPCs) play an important role in endothelial vascular development and endothelial repair. The upregulation of functional gene expression in EPCs may contribute to the maintenance of EPC-based endothelial repair. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a powerful regulator of mitochondrial biogenesis and antioxidant defense, but its impact on early EPCs remains poorly understood. This study was designed to investigate whether decline in PGC-1α expression impairs in vitro adhesion, migration, and in vivo reendothelialization capacity of early EPCs from patients with hypertension. We engineered an over-expression of PGC-1α within EPCs from hypertensive patients, which were transduced with an adenoviral vector encoding the human PGC-1α gene. Then we tested the migration and adhesion function of EPCs in vitro and endothelium-reparative capacity in vivo with a nude mouse model of carotid artery injury. Our data revealed for the first time that PGC-1α expression of EPCs is lower in hypertensive patients than that in healthy subjects. Meanwhile, the in vitro adhesion and migration function, in vivo endothelial repair capacity of early EPCs were significantly reduced in hypertensive patients compared with normal subjects. Furthermore, PGC-1α gene transfer contributes to increased adhesion in vitro and enhanced endothelium-reparative capacity in vivo of EPCs from hypertensive patients through the augmented expression of PGC-1α. Thus, upregulation of PGC-1α expression of EPCs may be a novel complementary therapeutic target to increase endothelium-reparative capacity in hypertensive patients.

Adhesion, intracellular signalling and osteogenic differentiation of mesenchymal progenitor cells and preosteoblasts on poly(epsilon)caprolactone films functionalized by peptides derived from fibronectin and/or BMP-9.

Biomaterials that can control the behaviour of stem cells play a major role in regenerative medicine and tissue engineering. We previously showed that poly(epsilon)caprolactone (PCL) films functionalized with adhesive peptides containing sequences of both cell binding domain (RGD) and synergistic site (PHSRN) of the fibronectin (pFibro) enhanced the osteoblastic commitment of C3H10T1/2 mesenchymal progenitor cells (C3H10T1/2 cells) induced by soluble BMP-9 or its derived peptide SpBMP-9. Here, the effect of PCL films functionalized with pFibro and/or SpBMP-9 or its negative peptide NSpBMP-9 on adhesion and intracellular signalling of C3H10T1/2 cells was determined. The differentiation of adherent C3H10T1/2 cells and MC3T3-E1 preosteoblasts into osteoblasts was also analysed with or without IGF-2, since this growth factor can favour the osteoblastic differentiation induced by BMP-9. We found that pFibro and SpBMP-9 co-functionalization on PCL films promoted the adhesion of C3H10T1/2 cells with well-organized focal adhesion points and FAK activation. In these mesenchymal progenitor cells, PCL-SpBMP-9 and PCL-pFibro/SpBMP-9 induced the activation and nuclear translocation of Smad 1/5 after 4h, and enhanced the protein expression of RUNX2 (3 d) and alkaline phosphatase (ALP) activity (7 d), two markers of osteoblast differentiation. No PPARγ, a marker of adipogenic differentiation, was detected. C3H10T1/2 cells attached to PCL-SpBMP-9 also contained more SOX9, a marker of chondroblastic lineage, compared with other experimental conditions. The use of inactive peptides NSpBMP-9 confirmed the specificity and effectiveness of SpBMP-9 on cell adhesion, intracellular signalling and osteoblastic differentiation. Adding IGF-2 only significantly improved the differentiation of MC3T3-E1 preosteoblasts into osteoblasts as shown by the increase in gene expression encoding Osterix (mRNA Sp7) and ALP (mRNA Alpl), probably because of the lack of serum in the medium. Therefore, material surface co-functionalized with pFibro and SpBMP-9 could be most useful for developing scaffolds with both osseointegrative and osteoinductive properties for bone application and tissue engineering strategy when combined with IGF-2 in serum free medium.