Vasculogenic and osteogenesis-enhancing potential of human umbilical cord blood endothelial colony-forming cells.

Umbilical cord blood-derived endothelial colony-forming cells (UCB-ECFC) show utility in neovascularization, but their contribution to osteogenesis has not been defined. Cocultures of UCB-ECFC with human fetal-mesenchymal stem cells (hfMSC) resulted in earlier induction of alkaline phosphatase (ALP) (Day 7 vs. 10) and increased mineralization (1.9×; p < .001) compared to hfMSC monocultures. This effect was mediated through soluble factors in ECFC-conditioned media, leading to 1.8-2.2× higher ALP levels and a 1.4-1.5× increase in calcium deposition (p < .01) in a dose-dependent manner. Transcriptomic and protein array studies demonstrated high basal levels of osteogenic (BMPs and TGF-ßs) and angiogenic (VEGF and angiopoietins) regulators. Comparison of defined UCB and adult peripheral blood ECFC showed higher osteogenic and angiogenic gene expression in UCB-ECFC. Subcutaneous implantation of UCB-ECFC with hfMSC in immunodeficient mice resulted in the formation of chimeric human vessels, with a 2.2-fold increase in host neovascularization compared to hfMSC-only implants (p = .001). We conclude that this study shows that UCB-ECFC have potential in therapeutic angiogenesis and osteogenic applications in conjunction with MSC. We speculate that UCB-ECFC play an important role in skeletal and vascular development during perinatal development but less so in later life when expression of key osteogenesis and angiogenesis genes in ECFC is lower.

Fetal stem cell microchimerism: natural-born healers or killers?

After four decades of study, the biological role of fetal microchimerism (FMC) remains elusive. Transfer of fetal cells to the mother begins soon after implantation, and increases with gestational age. FMC cells then decline after delivery, but remain detectable for years post-partum. These cells have been implicated in rheumatoid arthritis remission during pregnancy and the prevention of breast cancer by graft-versus-tumor-effects. However, any beneficial effects contrast with their suspected malevolence in triggering of systemic sclerosis after childrearing or their stromal support for tumor formation. Recent evidence that FMC cells participate in disease and tissue repair has stirred controversy on their origin. The detection of FMC cells during early embryogenesis together with the diversity of hematopoietic, mesenchymal and endothelial markers, and plasticity of morphology when integrated into various tissues, provides evidence for their stemness. However, proof of their phenotype in conventional stem cell differentiation assays has been beset with difficulty in isolating and expanding them in culture. Unraveling the function of FMC cells will provide insight into both their engagement in disease and their therapeutic potential.

Microgel iron oxide nanoparticles for tracking human fetal mesenchymal stem cells through magnetic resonance imaging.

Stem cell transplantation for regenerative medicine has made significant progress in various injury models, with the development of modalities to track stem cell fate and migration post-transplantation being currently pursued rigorously. Magnetic resonance imaging (MRI) allows serial high-resolution in vivo detection of transplanted stem cells labeled with iron oxide particles, but has been hampered by low labeling efficiencies. Here, we describe the use of microgel iron oxide (MGIO) particles of diameters spanning 100-750 nm for labeling human fetal mesenchymal stem cells (hfMSCs) for MRI tracking. We found that MGIO particle uptake by hfMSCs was size dependent, with 600-nm MGIO (M600) particles demonstrating three- to sixfold higher iron loading than the clinical particle ferucarbotran (33-263 versus 9.6-42.0 pg iron/hfMSC; p < .001). Cell labeling with either M600 particles or ferucarbotran did not affect either cellular proliferation or tri-lineage differentiation into osteoblasts, adipocytes, and chondrocytes, despite differences in gene expression on a genome-wide microarray analysis. Cell tracking in a rat photothrombotic stroke model using a clinical 1.5-T MRI scanner demonstrated the migration of labeled hfMSCs from the contralateral cortex to the stroke injury, with M600 particles achieving a five- to sevenfold higher sensitivity for MRI detection than ferucarbotran (p < .05). However, model-related cellular necrosis and acute inflammation limited the survival of hfMSCs beyond 5-12 days. The use of M600 particles allowed high detection sensitivity with low cellular toxicity to be achieved through a simple incubation protocol, and may thus be useful for cellular tracking using standard clinical MRI scanners.

C5a-induced expression of P-selectin in endothelial cells.

Human umbilical vein endothelial cells have recently been shown to respond to C5a with increases in intracellular Ca2+, production of D-myo-inositol 1,4,5-triphosphate and superoxide anion generation. In the current studies, C5a had been found to cause in a time- and dose-dependent manner rapid expression of endothelial P-selectin, secretion of von Willebrand factor, and adhesiveness for human neutrophils. The effects of C5a in P-selectin expression and adhesiveness of neutrophils were similar to the effects of histamine and thrombin on endothelial cells. The adhesiveness of C5a-stimulated endothelium for neutrophils was blocked by anti-P-selectin, but not by antibodies to intercellular adhesion molecule 1, E-selectin, or CD18. A cell-based ELISA technique has confirmed upregulation of P-selectin in endothelial cells exposed to C5a. Binding of C5a to endothelial cells has been demonstrated, with molecules bound being approximately 10% of those binding to neutrophils. By a reverse transcriptase-PCR technique, endothelial cells have been shown to contain mRNA for the C5a receptor. These data suggest that C5a may be an important inflammatory mediator for the early adhesive interactions between neutrophils and endothelial cells in the acute inflammatory response.

[Decubitus or incontinence-associated dermatitis?]. / Dermatitis of decubitus bij incontinentie.

A lack of understanding about the distinction between incontinence-associated dermatitis and pressure sores leads to inadequate treatment and therefore a higher incidence of pressure sores. Pressure relief may not be adequately carried out due to concentration exclusively on treatment of incontinence. In this article we will discuss the multifactorial approach, based on 2 patient cases. In order to prevent pressure sores, the cause of incontinence has to be investigated and treated if possible. Appropriate pressure relief must be carried out, in addition to adequate skin care.

Regionally-specified second trimester fetal neural stem cells reveals differential neurogenic programming.

Neural stem/progenitor cells (NSC) have the potential for treatment of a wide range of neurological diseases such as Parkinson Disease and multiple sclerosis. Currently, NSC have been isolated only from hippocampus and subventricular zone (SVZ) of the adult brain. It is not known whether NSC can be found in all parts of the developing mid-trimester central nervous system (CNS) when the brain undergoes massive transformation and growth. Multipotent NSC from the mid-trimester cerebra, thalamus, SVZ, hippocampus, thalamus, cerebellum, brain stem and spinal cord can be derived and propagated as clonal neurospheres with increasing frequencies with increasing gestations. These NSC can undergo multi-lineage differentiation both in vitro and in vivo, and engraft in a developmental murine model. Regionally-derived NSC are phenotypically distinct, with hippocampal NSC having a significantly higher neurogenic potential (53.6%) over other sources (range of 0%-27.5%, p<0.004). Whole genome expression analysis showed differential gene expression between these regionally-derived NSC, which involved the Notch, epidermal growth factor as well as interleukin pathways. We have shown the presence of phenotypically-distinct regionally-derived NSC from the mid-trimester CNS, which may reflect the ontological differences occurring within the CNS. Aside from informing on the role of such cells during fetal growth, they may be useful for different cellular therapy applications.

Neo-vascularization and bone formation mediated by fetal mesenchymal stem cell tissue-engineered bone grafts in critical-size femoral defects.

Tissue-engineered bone grafts (TEBG) require highly osteogenic cell sources for use in fracture repair applications. Compared to other sources of mesenchymal stem cells (MSC), human fetal MSC (hfMSC) have recently been shown to be more proliferative and osteogenic. We studied the functional performance of hfMSC-mediated TEBG in 7 mm rat femoral critical-sized bone defects (CSD). Dynamically-cultured and osteogenically-primed hfMSC seeded onto macroporous poly-epsilon-caprolactone tri-calcium phosphate scaffolds were transplanted into CSDs. After 12 weeks, hfMSC-mediated TEBG induced 2.1x more new bone formation (43.3+/-10.5 vs. 21.0+/-7.4 mm(3), p<0.05), with greater compact and woven bone, and a 9.8x increase in stiffness (3.9+/-1.7 vs. 0.4+/-0.3 mNm/degree, p<0.05) compared to acellular scaffolds, such that only animals transplanted with TEBG underwent full fracture repair of the CSD. Although hfMSC survived for <4 weeks, by 4 weeks they were associated with a 3.9x larger vasculature network in the defect area (35.2+/-11.1 vs. 6.5+/-3.6 mm(3)p<0.05), suggesting an important role for hfMSC in the promotion of neo-vasculogenesis. We speculate that hfMSC-mediated healing of the CSD by stimulating neo-vascularization through as yet undetermined mechanisms. This proof-of-principle study demonstrates the utility of primitive MSC for bone regeneration, and may be of relevance to vascularization in other areas of regenerative medicine.

The use of microgel iron oxide nanoparticles in studies of magnetic resonance relaxation and endothelial progenitor cell labelling.

In vivo tracking of stem cells after transplantation is crucial for understanding cell-fate and therapeutic efficacy. By labelling stem cells with magnetic particles, they can be tracked by Magnetic Resonance Imaging (MRI). We previously demonstrated that microgel iron oxide nanoparticle (MGIO) provide superior tracking sensitivity over commercially available particles. Here, we describe the synthesis of MGIO and report on their morphology, hydrodynamic diameters (87-766 nm), iron oxide weight content (up to 82%) and magnetization characteristics (M(s)=52.9 Am(2)/kg, M(R)=0.061 Am(2)/kg and H(c)=0.672 A/m). Their MR relaxation characteristics are comparable to those of theoretical models and represent the first such correlation between model and real particles of varying diameters. A labelling study of primary endothelial progenitor cells also confirms that MGIO is an efficient label regardless of cell type. The facile synthesis of MGIO makes it a useful tool for the studying of relaxation induced by magnetic particles and cellular tracking by MRI.

Pharmacokinetics/genotype associations for major cytochrome P450 enzymes in native and first- and third-generation Japanese populations: comparison with Korean, Chinese, and Caucasian populations.

Application of foreign clinical data across geographic regions can accelerate drug development. Drug disposition can be variable, and identification of factors influencing responsible pharmacokinetic/pharmacogenomic approaches could facilitate the universal application of foreign data and reduce the total amount of phase III clinical trials evaluating risks in different populations. Our objective was to establish and compare genotype (major cytochrome P450 (CYP) enzymes)/phenotype associations for Japanese (native and first- and third-generation Japanese living abroad), Caucasian, Chinese, and Korean populations using a standard drug panel. The mean metabolic ratios (MRs) for the four ethnic groups were similar except for a lower activity of CYP2D6 in Caucasians and CYP2C19 in Asians. Genotype, not ethnicity, impacted the MR for CYP2C9, CYP2C19, and CYP2D6; neither affected CYP1A2, CYP2E1, and CYP3A4/5 activities. We conclude that equivalent plasma drug concentrations and metabolic profiles can be expected for native Japanese, first- and third-generation Japanese, Koreans, and Chinese for compounds handled through these six CYP enzymes.

RNA expression in the early characterization of hepatotoxicants in Wistar rats by high-density DNA microarrays.

High-density microarrays are useful tools to study gene expression for the purpose of characterizing functional tissue changes in response to the action of drugs and chemicals. To test whether high-density expression data can identify mechanisms of toxicity and to identify an unknown sample through its RNA expression pattern, groups of male Wistar rats were administered 6 hepatotoxicants. The compounds chosen for this study were microcystin-LR (MLR), phenobarbital (PB), lipopolysaccharide (LPS), carbon tetrachloride (CT), thioacetamide (THA), and cyproterone acetate (CPA). These hepatotoxicants are known to induce adverse liver effects through different mechanisms. Liver mRNA was isolated and used to generate biotinylated cRNA for hybridization to a custom 1,600-rat gene DNA microarray. Treatment correlation matrices analyzed hybridization data from a hepatotoxicant-blinded sample, with gene expression coefficients (GEC) evaluated by means of hierarchical cluster analysis and visual representation as dendrograms. The experimental liver toxicity from the different treatments was confirmed by means of concurrent histopathology, liver enzymes, and bilirubin assays. This toxico genomic analysis identified multiple genes and groups of genes that were affected by the hepatotoxicants on study, indicating that high-density microarray expression data are useful to identify groups of genes involved in toxicity. In addition, the mRNA expression profile of an unidentified sample can be accurately identified when compared with the expression profiles resident in the data set. This study supports the use of gene expression-profiling technology to determine or to predict toxic liver effects.