Stefano Pietronave

Conjugation of hydroxyapatite nanocrystals with human immunoglobulin G for nanomedical applications.

Inorganic nanosized drug carriers are a promising field in nanomedicine applied to cancer. Their conjugation with antibodies combines the properties of the nanoparticles themselves with the specific and selective recognition ability of the antibodies to antigens. Biomimetic carbonate-hydroxyapatite (HA) nanoparticles were synthesized and fully characterized; human IgGs, used as model antibodies, were coupled to these nanocrystals. The maximum loading amount, the interaction modelling, the preferential orientation and the secondary structure modifications were evaluated using theoretical models (Langmuir, Freundlich and Langmuir-Freundlich) spectroscopic (UV-Vis, Raman), calorimetric (TGA), and immunochemical techniques (ELISA, Western Blot). HA nanoparticles of about 30 nm adsorbed human IgGs, in a dose-dependent, saturable and stable manner with micromolar affinity and adsorption capability around 2.3 mg/m(2). Adsorption isotherm could be described by Langmuir-Freundlich model, and was due to both energetically homogeneous and heterogeneous binding sites on HA surface, mainly of electrostatic nature. Binding did not induce secondary structure modification of IgGs. A preferential IgG end-on orientation with the involvement of IgG Fc moiety in the adsorption seems most probable due to the steric hindrance of their Fab domains. Biomimetic HA nanocrystals are suitable substrates to produce nanoparticles which can be functionalized with antibodies for efficient targeted drug delivery to tumours.

Human cardiac progenitor cell grafts as unrestricted source of supernumerary cardiac cells in healthy murine hearts.

Human heart harbors a population of resident progenitor cells that can be isolated by stem cell antigen‐1 antibody and expanded in culture. These cells can differentiate into cardiomyocytes in vitro and contribute to cardiac regeneration in vivo. However, when directly injected as single cell suspension, less than 1%‐5% survive and differentiate. Among the major causes of this failure are the distressing protocols used to culture in vitro and implant progenitor cells into damaged hearts. Human cardiac progenitors obtained from the auricles of patients were cultured as scaffoldless engineered tissues fabricated using temperature‐responsive surfaces. In the engineered tissue, progenitor cells established proper three‐dimensional intercellular relationships and were embedded in self‐produced extracellular matrix preserving their phenotype and multipotency in the absence of significant apoptosis. After engineered tissues were leant on visceral pericardium, a number of cells migrated into the murine myocardium and in the vascular walls, where they integrated in the respective textures.

Cooperation of Biological and Mechanical Signals in Cardiac Progenitor Cell Differentiation

Dr. S. Pagliari , Dr. G. Forte , Dr. F. Pagliari , Dr. M. Minieri , Prof. P. Di Nardo Laboratory of Molecular and Cellular Cardiology Department of Internal Medicine University of Rome “Tor Vergata”Rome 00133, Italy E-mail: dinardo@uniroma2.it Dr. S. Pagliari, Dr. G. Forte, Dr. F. Pagliari, Dr. M. Minieri, Prof. P. Di NardoJapanese-Italian Tissue Engineering Laboratory (JITEL) Tokyo Women’s Medical University-Waseda University Joint Institution for Advanced Biomedical Sciences (TWIns) Tokyo, Japan Dr. S. Pagliari, Dr. G. Forte, Dr. F. Pagliari, Dr. M. Minieri, Prof. P. Di NardoItalian Institute for Cardiovascular Research (INRC) 40126 Bologna, Italy Prof. A. C. Vilela-Silva Instituto de Ciencias Biomedicas and Laboratorio de Tecido Conjuntivo Hospital Universitario Clementino Fraga Filho Rio de Janeiro, Brazil Dr. C. Mandoli , Prof. E. Traversa International Research Center for Materials Nanoarchitectonics (MANA) National Institute for Materials Science (NIMS) 1–1 Namiki, Tsukuba, Ibaraki 305–0044, Japan E-mail: TRAVERSA.Enrico@nims.go.jp Dr. S. Pietronave , Prof. M. Prat Department of Medical Sciences University “A. Avogadro” of Piemonte Orientale 28100 Novara, Italy Dr. G. Vozzi , Prof. A. Ahluwalia Interdepartmental Research Center “E. Piaggio” University of Pisa56126 Pisa, Italy Prof. S. Licoccia , Prof. E. Traversa NAST Centre & Department of Chemical Science and Technology University of Rome “Tor Vergata” Roma 00133, Italy [†] S.P. and A.C.V.S. contributed equally to this work.

Functionalized nanomaterials for diagnosis and therapy of cancer.

Recent developments in nanotechnology have provided new tools for both cancer imaging and treatment. The functionalization of the nanocarrier based drugs using biological ligands allows increasing specificity of drug targeting enhancing efficacy and reducing side effects. In this paper some current nanocarrier based drugs are described and the principles for their functionalization in cancer treatment and imaging are reviewed.

Deletion of the ectodomain unleashes the transforming, invasive, and tumorigenic potential of the MET oncogene

The c‐MET proto‐oncogene, encoding the p190 hepatocyte growth factor tyrosine kinase receptor, can acquire oncogenic potential by multiple mechanisms, such as gene rearrangement, amplification and overexpression, point mutation, and ectopic expression, all resulting in its constitutive activation. Hepatocyte growth factor receptor truncated forms are generated by post‐translational cleavage: p140 and p130 lack the kinase domain and are inactive. Their C‐terminal remnant fragments are generally undetectable in normal cells, but a membrane‐associated truncated form is recognized by anti‐C‐terminus antibodies in some human tumors, suggesting that a hepatocyte growth factor receptor lacking the ectodomain, but retaining the transmembrane and intracellular domains (Met‐EC−), could acquire oncogenic properties. Herein we show that NIH‐3T3 cells transduced with MET‐EC− expressed a membrane‐associated constitutively tyrosine‐phosphorylated 60‐kDa protein and, similarly to NIH‐3T3 cells expressing the cytosolic oncoprotein Tpr‐Met, showed activated extracellular regulated kinase 1/2 mitogen‐activated protein kinase and Akt downstream transducers. Compared to control NIH‐3T3 cells, NIH‐3T3‐Met‐EC− cells grew faster and showed anchorage‐independent growth and invasive properties in all aspects similar to cells expressing the transforming TPR‐MET. Nude female mice injected subcutaneously with NIH‐3T3‐Met‐EC− cells developed visible tumors, displaying the typical morphology of carcinomas with polygonal cells, in contrast to sarcomas with spindle‐shaped cells induced by the injection of NIH‐3T3‐Tpr‐Met cells. It is suggested that the different subcellular localization of the oncoproteins, more than differences in signal transduction, could be responsible for the tumor phenotype. All together, these data show that deletion of the ectodomain activates the hepatocyte growth factor receptor and its downstream signaling pathways, unleashing its transforming, invasive, and tumorigenic potential. (Cancer Sci 2009; 100: 633–638)

Agonist monoclonal antibodies against HGF receptor protect cardiac muscle cells from apoptosis

Hepatocyte growth factor (HGF), a pleiotropic cytokine with mitogenic, motogenic, morphogenic, and antiapoptotic effects in various cell types, is a cardioprotective growth factor that can counteract the loss of cardiomyocytes usually observed in cardiac diseases. HGF is a quite unstable molecule in its biologically active heterodimeric form. Since all HGF-induced biological responses are mediated by its high-affinity tyrosine kinase receptor (Met/HGF-R) encoded by the Met gene, we asked whether a monoclonal antibody (MAb) that displays receptor full agonist activity could protect cardiac muscle cell lines from hydrogen peroxide-induced apoptosis. We report that the MAb efficiently inhibited hydrogen peroxide-induced cell shrinkage, DNA fragmentation, annexin V positivity, mitochondrial translocation of bax, and caspase activation. The MAb was thus able to counteract apoptosis evaluated by both morphological and biochemical criteria. The agonist activity of the MAb was mediated by Met/HGF-R, since a Met/HGF-R-specific short hairpin RNA (shRNA) inhibited both activation of transduction pathways and motility triggered by MAb DO-24. The protective antiapoptotic effect of MAb DO-24 was dependent on activation of the ras-MAPK Erk1/2 and phosphatidylinositol 3-kinase (PI3-kinase)-Akt transduction pathways, since it was abrogated by treatments with their specific pharmacological inhibitors, PD-98059 and wortmannin. Moreover, the MAb induced a motogenic, but not mitogenic, response in these cells, mimicking in all aspects the natural ligand HGF but displaying a significant higher stability than HGF in culture. This MAb may thus be a valuable substitute for HGF, being more easily available in a biologically active, highly stable, and purified form.

Monophasic and biphasic electrical stimulation induces a precardiac differentiation in progenitor cells isolated from human heart.

Electrical stimulation (ES) of cells has been shown to induce a variety of responses, such as cytoskeleton rearrangements, migration, proliferation, and differentiation. In this study, we have investigated whether monophasic and biphasic pulsed ES could exert any effect on the proliferation and differentiation of human cardiac progenitor cells (hCPCs) isolated from human heart fragments. Cells were cultured under continuous exposure to monophasic or biphasic ES with fixed cycles for 1 or 3 days. Results indicate that neither stimulation protocol affected cell viability, while the cell shape became more elongated and reoriented more perpendicular to the electric field direction. Moreover, the biphasic ES clearly induced the upregulation of early cardiac transcription factors, MEF2D, GATA-4, and Nkx2.5, as well as the de novo expression of the late cardiac sarcomeric proteins, troponin T, cardiac alpha actinin, and SERCA 2a. Both treatments increased the expression of connexin 43 and its relocation to the cell membrane, but biphasic ES was faster and more effective. Finally, when hCPCs were exposed to both monophasic and biphasic ES, they expressed de novo the mRNA of the voltage-dependent calcium channel Cav 3.1(α1G) subunit, which is peculiar of the developing heart. Taken together, these results show that ES alone is able to set the conditions for early differentiation of adult hCPCs toward a cardiac phenotype.

Electrical conditioning of adipose‐derived stem cells in a multi‐chamber culture platform

In tissue engineering, several factors play key roles in providing adequate stimuli for cells differentiation, in particular biochemical and physical stimuli, which try to mimic the physiological microenvironments. Since electrical stimuli are important in the developing heart, we have developed an easy‐to‐use, cost‐effective cell culture platform, able to provide controlled electrical stimulation aimed at investigating the influence of the electric field in the stem cell differentiation process. This bioreactor consists of an electrical stimulator and 12 independent, petri‐like culture chambers and a 3‐D computational model was used to characterize the distribution and the intensity of the electric field generated in the cell culture volume. We explored the effects of monophasic and biphasic square wave pulse stimulation on a mouse adipose‐derived stem cell line (m17.ASC) comparing cell viability, proliferation, protein, and gene expression. Both monophasic (8 V, 2 ms, 1 Hz) and biphasic (+4 V, 1 ms and −4 V, 1 ms; 1 Hz) stimulation were compatible with cell survival and proliferation. Biphasic stimulation induced the expression of Connexin 43, which was found to localize also at the cell membrane, which is its recognized functional mediating intercellular electrical coupling. Electrically stimulated cells showed an induced transcriptional profile more closely related to that of neonatal cadiomyocytes, particularly for biphasic stimulation. The developed platform thus allowed to set‐up precise conditions to drive adult stem cells toward a myocardial phenotype solely by physical stimuli, in the absence of exogenously added expensive bioactive molecules, and can thus represent a valuable tool for translational applications for heart tissue engineering and regeneration. Biotechnol. Bioeng. 2014;111: 1452–1463.

Different expression and function of the endocannabinoid system in human epicardial adipose tissue in relation to heart disease

BACKGROUND The endocannabinoid system reportedly plays a role in the pathogenesis of cardiovascular diseases. This system is expressed also in adipose tissue, which could thus be involved in cardiac disorders through modulation of metabolically triggered inflammation. The current study aims to determine the relevance of the endocannabinoid system in epicardial adipose tissue in heart disease. METHODS Expression of the endocannabinoid receptors CB1 and CB2, and of the endocannabinoid-degrading enzyme, fatty acid amidohydrolase, and activation of protein kinase A (PKA), phospholipase C (PLC), protein kinase C (PKC), endothelial nitric oxide synthase (eNOS) and inducible (i)NOS, and extracellular signal-regulated kinases 1 and 2 (ERK1/2) (a member of the reperfusion-injury salvage kinase pathway), were analyzed by Western blot in patients after coronary artery bypass surgery (ischemics; N = 18) or valve surgery (nonischemics; N = 15) and in preadipocytes isolated from epicardial adipose tissue. RESULTS In ischemics, the CB1-to-CB2 expression ratio shifted toward CB1 and was accompanied by higher PKA activation. In contrast, in nonischemics, CB2, fatty acid amidohydrolase, PLC and PKC, and ERK1/2 were upregulated. Moreover, NO production and iNOS-to-eNOS ratios were higher in preadipocytes from ischemics. CONCLUSIONS These results show a different modulation and functioning of the endocannabinoid system in ischemics compared with nonischemics. Hence, while CB2, PLC and PKC, ERK1/2, and eNOS are more strongly expressed in patients without ischemic heart disease, high CB1 and PKA expression is associated with low survival intracellular pathway activation and high iNOS activation in ischemic heart disease patients. The changes in the endocannabinoid system in ischemics may contribute to cardiac dysfunction and therefore represents a potential therapeutic target.

Isolation and Characterization of a Spontaneously Immortalized Multipotent Mesenchymal Cell Line Derived from Mouse Subcutaneous Adipose Tissue

The emerging field of tissue engineering and regenerative medicine is a multidisciplinary science that is based on the combination of a reliable source of stem cells, biomaterial scaffolds, and cytokine growth factors. Adult mesenchymal stem cells are considered important cells for applications in this field, and adipose tissue has revealed to be an excellent source of them. Indeed, adipose-derived stem cells (ASCs) can be easily isolated from the stromal vascular fraction (SVF) of adipose tissue. During the isolation and propagation of murine ASCs, we observed the appearance of a spontaneously immortalized cell clone, named m17.ASC. This clone has been propagated for more than 180 passages and stably expresses a variety of stemness markers, such as Sca-1, c-kit/CD117, CD44, CD106, islet-1, nestin, and nucleostemin. Furthermore, these cells can be induced to differentiate toward osteogenic, chondrogenic, adipogenic, and cardiogenic phenotypes. m17.ASC clone displays a normal karyotype and stable telomeres; it neither proliferates when plated in soft agar nor gives rise to tumors when injected subcutaneously in NOD/SCID-γ (null) mice. The analysis of gene expression highlighted transcriptional traits of SVF cells. m17.ASCs were genetically modified by lentiviral vectors carrying green fluorescent protein (GFP) as a marker transgene and efficiently engrafted in the liver, when injected in the spleen of NOD/SCID-γ (null) monocrotaline-treated mice. These results suggest that this non-tumorigenic spontaneously immortalized ASC line may represent a useful tool (cell model) for studying the differentiation mechanisms involved in tissue repair as well as a model for pharmacological/toxicological studies.