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. The study demonstrates the suitability of such an approach to deliver stem cells to the myocardium. Interestingly, the successful delivery of cells in murine healthy hearts suggests that myocardium displays a continued cell cupidity that is strictly regulated by the limited release of progenitor cells by the adopted source. When an unregulated cell source is added to the system, cells are delivered to the myocardium. The exploitation of this novel concept may pave the way to the setup of new protocols in cardiac cell therapy.

Advances and applications of induced pluripotent stem cells

Direct reprogramming of somatic cells into pluripotent cells is an emerging technology for creating patient-specific cells, and potentially opens new scenarios in medical and pharmacological fields. From the discovery of Shinya Yamanaka, who first obtained pluripotent cells from fibroblasts by retrovirus-derived ectopic expression of defined embryonic transcription factors, new methods have been developed to generate safe induced pluripotent stem (iPS) cells without genomic manipulations. This review will focus on the recent advances in iPS technology and their application in pharmacology and medicine.

Discrete salt crystallization at the surface of a porous medium

Efflorescence refers to crystallized salt structures that form at the surface of a porous medium. The challenge is to understand why these structures do not form everywhere at the surface of the porous medium but at some specific locations and why there exists an exclusion distance around an efflorescence where no new efflorescence forms. These are explained from a visualization experiment, pore-network simulations and a simple efflorescence growth model.

Slow invasion of a nonwetting fluid from multiple inlet sources in a thin porous layer

We numerically study the process of quasistatic invasion of a nonwetting fluid in 2D and 3D porous layers from multiple inlet injection sources and show that a porous layer acts as a two-phase filter as a result of the repeated convergence of flow paths: The probability for a pore at the outlet to be a breakthrough point is significantly lower than the fraction of active injection points at the inlet owing to the merging within the porous layer of liquid paths originating from different inlet injection points. The study of the breakthrough point statistics indicates that the number of breakthrough points diminishes with the system thickness and that the behavior of thin layers, defined here as systems of typical thicknesses of less than 15 lattice spacing units (≈15 pore or grain mean sizes), is distinct from thicker layers. For thicker systems, it is found that the probability of an outlet pore to be a breakthrough pore scales as l(1-d) where l is the system thickness and d is the space dimensionality, whereas, a power law behavior is not obtained with a thin system. Other properties, such as the invading phase occupancy profiles are studied. We also described a kinetic algorithm that allowed us to compute the occurrence times of breakthrough points. The distribution of these times is markedly different in 2D and in 3D.

Cell therapy of burns

Severe burns remain a life-threatening local and general inflammatory condition often with serious sequelae, despite remarkable progress in their treatment over the past three decades. Cultured epidermal autografts, the first and still most up-to-date cell therapy for burns, plays a key role in that progress, but drawbacks to this need to be reduced by using cultured dermal-epidermal substitutes. This review focuses on what could be, in our view, the next major breakthrough in cell therapy of burns - use of mesenchymal stromal cells (MSCs). After summarizing current knowledge, including our own clinical experience with MSCs in the pioneering field of cell therapy of radiation-induced burns, we discuss the strong rationale supporting potential interest in MSCs in treatment of thermal burns, including limited but promising pre-clinical and clinical data in wound healing and acute inflammatory conditions other than burns. Practical options for future therapeutic applications of MSCs for burns treatment, are finally considered.

Diacylglycerol kinases are essential for hepatocyte growth factor-dependent proliferation and motility of Kaposi's sarcoma cells

Hepatocyte growth factor (HGF) is involved in the pathogenesis of Kaposi's sarcoma (KS), the most frequent neoplasia in patients with AIDS, characterized by proliferating spindle cells, infiltrating inflammatory cells, angiogenesis, edema, and invasiveness. In vitro, this factor sustains the biological behavior of KS derived cells, after activation of its receptor and the downstream MAPK and AKT signals. In other cell types, namely endothelial and epithelial cells, movement, proliferation, and survival stimulated by HGF and other growth factors and cytokines depend on diacylglycerol kinases (DGK). In an effort to identify new intracellular transducers operative in KS cells, which could represent therapeutic targets, we investigated the role of DGK in KS cell movement and proliferation by treating cells with the DGK pharmacological inhibitor R59949. We report that R59949 strongly inhibits HGF-induced KS motility, proliferation, and anchorage-independent growth with only a partial effect on cell adhesion and spreading. R59949 does not affect cell survival, HGF receptor activation, or the classical MAPK and AKT signalling pathways. Furthermore, we carried out an siRNA screen to characterize the DGK isoforms involved in KS motility and anchorage independent growth. Our data indicate a strong involvement of DGK-δ in KS motility and of DGK-ι in anchorage-independent growth. These results indicate that DGK inhibition is sufficient to impair in vitro KS cell proliferation and movement and suggest that selected DGK represent new pharmacological targets to interfere with the malignant properties of KS, independently from the well-known RAS/MAPK and PI3K/AKT pathways.

Abstract 3272: A Met receptor docking site peptide fused to cell-penetrating sequences acts as a powerful inhibitor of angiogenesis and vascular tumour growth

Introduction: Hepatocyte growth factor (HGF) is a potent mitogenic, motogenic and morphogenic factor with angiogenic properties; it directly or indirectly stimulates endothelial cells favouring tumour expansion and HGF receptor activation in cancer cells. Kaposi's sarcoma (KS), the most frequent neoplasia in patients with AIDS, which originates from endothelial origin and is highly vascularized, shows features compatible with the biological properties of HGF. We decided to develop angiogenesis inhibitors that target the HGF pathway, impairing tumour neo-vascularization and metastatic spreading. We investigated the anti-angiogenic properties of synthetic peptides mimicking the docking site of Met receptor on human endothelial cells (HUVEC) and KS. We also analyzed the role of diacylglycerol kinases (DGK) in KS cell responses.

Material and methods: To evaluate the effect of Met-derived inhibitors on angiogenesis, we treated HUVEC with peptides containing Met docking site fused to the internalization sequences of Antennapedia homeodomain or of Tat transactivation domain which were used to deliver peptides into living cells. We evaluated the ability of peptides to interfere with HGF-induced proliferation, migration and morphogenesis of endothelial cells in vitro and angiogenesis and tumor growth in vivo. To investigate the role of DGK in the different biological responses elicited by HGF in the Kaposi’ sarcoma cells, we treated KS cells with the DGK pharmacological inhibitor R59949.

Results: We observed that in endothelial cells internalized peptides inhibited ligand-dependent cell proliferation, motility, invasiveness and morphogenesis in vitro, which correlated with interference of HGF-dependent downstream signalling. In vivo, the peptides inhibited HGF-induced angiogenesis and Kaposi's sarcoma tumour growth. DGK plays an essential role in KS cell proliferation.

Conclusion: the data obtained on endothelial cells show that the carboxyl-terminal sequence of Met fused to the internalization sequences of Antennapedia homeodomain or of Tat transactivation domain impairs angiogenesis triggered by HGF, suggesting the use of anti-docking site compounds as therapeutic agents to interfere with the angiogenesis process. The demonstration that DGK is essential for KS growth suggests that these enzymes are promising target for a pharmacological intervention on KS cells. The development of angiogenesis inhibitors and the identification of new intracellular transducers effective in the high vascularised KS cells, open the possibility of a combination therapy that concomitantly interferes with tumour neo-vascularization and the malignant properties of KS.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3272. doi:10.1158/1538-7445.AM2011-3272

Pharmacological postconditioning protects against hepatic ischemia/reperfusion injury

Postconditioning is a procedure based on the induction of intracellular protective reactions immediately after the onset of reperfusion. Because of the growing need to prevent ischemia/reperfusion (I/R) injury during liver surgery and transplantation, we investigated the possibility of pharmacologically inducing hepatic postconditioning. The effects of the adenosine A2A receptor agonist 2p-(2-carboxyethyl)-phenyl-amino-5'-N-ethylcarboxyamido-adenosine (CGS21680; 5 μmol/L) and the phosphatase and tensin homologue deleted from chromosome 10 (PTEN) inhibitor dipotassium bisperoxo-(5-hydroxypyridine-2-carboxyl)-oxovanadate [bpV(HOpic); 250 nmol/L] were investigated in primary rat hepatocytes during reoxygenation after 24 hours of cold storage and in an in vivo model of rat liver warm I/R. The addition of CGS21680 at reoxygenation significantly reduced hepatocyte death through the activation of the phosphoinositide 3-kinase (PI3K)-protein kinase B (PKB)/Akt signal pathway and through the reduction of the intracellular level of PTEN. PTEN lowering was associated with the increased generation of reactive oxygen species after A2A receptor-mediated stimulation of β-nicotinamide adenine dinucleotide phosphate oxidase (NOX). The inhibition of PI3K or NOX with wortmannin or diphenyleneiodonium chloride, respectively, and the addition of the antioxidant N,N'-diphenyl-p-phenylenediamine reversed the effects of CGS21680. The PTEN inhibitor bpV(HOpic) mimicked the protection provided by CGS21680 against reoxygenation damage. An in vivo rat treatment with CGS21680 or bpV(HOpic) during reperfusion after 1 hour of partial hepatic ischemia also promoted PKB/Akt activation and ameliorated alanine aminotransferase release and histological lesions induced by 2 hours of reperfusion. We conclude that adenosine A2A receptor agonists and PTEN inhibitors are possibly useful agents for the pharmacological induction of postconditioning in the liver.

The cooperative effect of size and crystallinity degree on the resorption of biomimetic hydroxyapatite for soft tissue augmentation

Two kinds of hydroxyapatite (HA) crystals were studied as subcutaneous fillers in order to evaluate how their different degree of crystallinity and dimensions influence in vivo resorption. By appropriately adjusting the synthesis temperature, poorly crystalline HA (HApc) and highly crystalline HA (HAhc) were synthesized into clusters of needle-shaped crystals of about 50 nm and plate-shaped crystals of about 100 nm, respectively. The clusters of HApc had larger dimensions (30 µm) than those of HAhc (3 µm). Subcutaneous in vivo inoculations were performed in ten 6-month-old FVB female mice. HAhc underwent complete macroscopic resorption already 4 weeks after the implantation while HApc still showed agglomerates at the eighth week. This unexpected finding may be ascribed to the different size and morphology of the HAhc nanocrystals responsible for a lower aggregation and microcluster dimension than HApc nanocrystals.

Cell delivery of Met docking site peptides inhibit angiogenesis and vascular tumor growth

Hepatocyte growth factor (HGF) and its receptor Met are responsible for a wide variety of cellular responses, both physiologically during embryo development and tissue homeostasis, and pathologically, particularly during tumor growth and dissemination. In cancer, Met can act as an oncogene on tumor cells, as well as a pro-angiogenic factor activating endothelial cells and inducing new vessel formation. Molecules interfering with Met activity could be valuable therapeutic agents. Here we have investigated the antiangiogenic properties of a synthetic peptide mimicking the docking site of the Met carboxyl-terminal tail, which was delivered into the cells by fusion with the internalization sequences from Antennapedia or HIV-Tat. We showed that these peptides inhibit ligand-dependent endothelial cell proliferation, motility, invasiveness and morphogenesis in vitro to an even greater extent and with much less toxicity than the Met inhibitor PHA-665752, which correlated with interference of HGF-dependent downstream signaling. In vivo, the peptides inhibited HGF-induced angiogenesis in the matrigel sponge assay and impaired xenograft tumor growth and vascularization in Kaposi's sarcoma. These data show that interference with the Met receptor intracellular sequence impairs HGF-induced angiogenesis, suggesting the use of antidocking site compounds as a therapeutic strategy to counteract angiogenesis in cancer as well as in other diseases.

Co-expression of plexin-B1 and Met in human breast and ovary tumours enhances the risk of progression

Background: Plex-B1, the receptor of Sema4D, has been implicated in tumour growth, angiogenesis and metastasis. The binding of Sema4D to Plex-B1 can trigger the activation of Met tyrosine kinase, thereby promoting cell dissociation and invasive growth. We tested the hypothesis that the expression of Plex-B1, either alone or in association with Met, can be of predictive value for tumour progression.

Methods: The expression and distribution of Plex-B1 and Met were investigated by immunohistochemistry and immunofluorescence in 50 human neoplasias originating in the breast and ovary, and correlated with clinical–pathological data at diagnosis.

Results: Plex-B1 and Met were individually expressed in 14% and in 24% of the tumours, respectively. Plex-B1 and Met were co-expressed in 24/50 cases (48%), and in the majority of these (83%) Met was tyrosine phosphorylated. The expression of Plex-B1 or Met alone showed no significant correlation with tumour aggressiveness, whereas advanced stage tumours (III–IV) frequently showed Plex-B1–Met double-positive (9/13). Tumours co-expressing Plex-B1 and Met were characterised by worse grading and higher incidence of lymph node metastases. Out of 22 tumours with lymph node metastases, as many as 19 were Plex-B1 and Met double-positive (p=0.0008), and 17 expressed phosphorylated Met (p=0.002).

Conclusions: Plex-B1 assumes a predictive value for unfavourable outcome when co-expressed with Met.

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.

Antral follicle count as a predictor of hyperresponse in controlled ovarian hyperstimulation/intrauterine insemination in unexplained sterility

In this prospective study of women with unexplained infertility undergoing the first cycle of controlled ovarian hyperstimulation/intrauterine insemination, the presence of 16 or more antral follicles on day 3 of the cycle was a good predictor of cancellation due to hyperresponse.

Three periods of drying of a single square capillary tube

The drying kinetics of a porous medium is classically described in three main periods, which depend on the interplay between the external and internal mass transfers during evaporation. The first period is described as essentially depending on the external mass transfer, whereas the third period is dominated by the internal mass transfer. The second period is a crossover period. We show experimentally that a similar drying kinetics can be obtained from a much simpler system owing to the effect of corner liquid films: a capillary tube of square cross section.