Antioxidant Solution in Combination with Angiotensin-(1-7) Provides Myocardial Protection in Langendorff-Perfused Rat Hearts.

As progressive organ shortage in cardiac transplantation demands extension of donor criteria, effort is needed to optimize graft survival. Reactive oxygen and nitrogen species, generated during organ procurement, transplantation, and reperfusion, contribute to acute and late graft dysfunction. The combined application of diverse substances acting via different molecular pathways appears to be a reasonable approach to face the complex mechanism of ischemia reperfusion injury. Thus, an antioxidant solution containing α-ketoglutaric acid, 5-hydroxymethylfurfural, N-acetyl-L-methionine, and N-acetyl-selenium-L-methionine was combined with endogenous angiotensin-(1-7). Its capacity of myocardial protection was investigated in isolated Langendorff-perfused rat hearts subjected to warm and cold ischemia. The physiological cardiac parameters were assessed throughout the experiments. Effects were evaluated via determination of the oxidative stress parameters malondialdehyde and carbonyl proteins as well as immunohistochemical and ultrastructural tissue analyses. It was shown that a combination of 20% (v/v) antioxidant solution and 220 pM angiotensin-(1-7) led to the best results with a preservation of heart tissue against oxidative stress and morphological alteration. Additionally, immediate cardiac recovery (after warm ischemia) and normal physiological performance (after cold ischemia) were recorded. Overall, the results of this study indicate substantial cardioprotection of the novel combination with promising prospective for future clinical use.

Histological processing of un-/cellularized thermosensitive electrospun scaffolds.

Histological processing of thermosensitive electrospun poly(ε-caprolactone)/poly(L-lactide) (PCL/PLA) scaffolds fails, as poly(ε-caprolactone) (PCL) is characterized by its low-melting temperature (Tm = 60 °C). Here, we present an optimized low-temperature preparation method for the histological processing of un-/cellularized thermosensitive PCL/PLA scaffolds.Our study is aimed at the establishment of an optimized dehydration and low-melting-point paraffin-embedding method of electrospun PCL/PLA scaffolds (un-/cellularized). Furthermore, we compared this method with (a) automatized dehydration and standard paraffin embedding, (b) gelatin embedding followed by automatized dehydration and standard paraffin embedding, (c) cryofixation, and (d) acrylic resin embedding methods. We investigated pepsin and proteinase K antigen retrieval for their efficiency in epitope demasking at low temperatures and evaluated protocols for immunohistochemistry and immunofluorescence for cytokeratin 7 (CK7) and in situ padlock probe technology for beta actin (ACTB). Optimized dehydration and low-melting-point paraffin embedding preserved the PCL/PLA scaffold, as the diameter and structure of its fibers were unchanged. Cells attached to the PCL/PLA scaffolds showed limited alterations in size and morphology compared to control. Epitope demasking by enzymatic pepsin digestion and immunostaining of CK7 displayed an invasion of attached cells into the scaffold. Expression of ACTB and CK7 was shown by a combination of mRNA-based in situ padlock probe technology and immunofluorescence. In contrast, gelatin stabilization followed by standard paraffin embedding led to an overall shrinkage and melting of fibers, and therefore, no further analysis was possible. Acrylic resin embedding and cyrofixation caused fiber structures that were nearly unchanged in size and diameter. However, acrylic resin-embedded scaffolds are limited to 3 µm sections, whereas cyrofixation led to a reduction of the cell size by 14% compared to low-melting paraffin embedding. The combination of low-melting-point paraffin embedding and pepsin digestion as an antigen retrieval method offers a successful opportunity for histological investigations in thermosensitive specimens.

Amnion-derived mesenchymal stem cells improve viability of endothelial cells exposed to shear stress in ePTFE grafts.

PURPOSE:: Blood vessel reconstruction is an increasing need of patients suffering from cardiovascular diseases. For the development of microvascular prostheses, efficient endothelialization is mandatory to prevent graft occlusion. Here, we assessed the impact of amnion-derived mesenchymal stem/stromal cells (hAMSC), known for their important angiogenic potential, on the integrity and stability of endothelial cells exposed to shear stress in vascular grafts. METHODS:: Human placental endothelial cells (hPEC) were cultured at the inner surface of an expanded polytetrafluoroethylene (ePTFE) graft positioned within a bioreactor and exposed to a minimal shear stress of 0.015 dyne/cm2 or a physiological shear stress of 0.92 dyne/cm2. hAMSC attached to the outer graft surface were able to interact with human placental endothelial cells by paracrine factors. RESULTS:: Microscopical analysis and evaluation of glucose/lactate metabolism evidenced successful cell seeding of the graft: hPEC formed a stable monolayer, hAMSC showed a continuous growth during 72 h incubation. hAMSC improved the viability of hPEC exposed to 0.015 dyne/cm2 as shown by a decreased lactate dehydrogenase release of 13% after 72 h compared to hPEC single culture. The viability-enhancing effect of hAMSC on hPEC was further improved by 13% under physiological shear stress. Angiogenesis array analysis revealed that hPEC exposed to physiological shear stress and hAMSC co-culture reduced the secretion of angiogenin, GRO, MCP-1, and TIMP-2. CONCLUSION:: hAMSC exerted best survival-enhancing effects on hPEC under exposure to physiological shear stress and modulated endothelial function by paracrine factors. Our data support further studies on the development of grafts functionalized with hAMSC-derived secretomes to enable fast clinical application.

Bai Hu Tang, Si Ni Tang, and Xue Bi Tang amplify pro-inflammatory activities and reduce apoptosis in endothelial cells in a cell culture model of sepsis.

ETHNOPHARMACOLOGICAL RELEVANCE: Sepsis is a systemic inflammatory response of the body to a severe infection or massive tissue injury. Despite intensive research, sepsis continues to have a high mortality rate and successful treatment options are strongly needed. Bai Hu Tang (BHT), Si Ni Tang (SNT), and Xue Bi Tang (XBT) are ancient traditional Chinese formulas derived from Chinese herbs that are used to treat Sepsis, but their mechanisms of activity are largely unknown. AIM OF THE STUDY: We aimed to examine dose-dependent effects of BHT, SNT, and XBT in a cell culture model of Sepsis, with special focus on endothelial cell apoptosis and the expression of monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)6, IL8, the surface adhesion molecule intercellular adhesion molecule-1 (ICAM-1) and endothelial-leukocyte adhesion molecule-1 (ELAM-1). MATERIAL AND METHODS: We stimulated THP1 monocytic cells with lipopolysaccharide (LPS, Escherichia coli (E. coli)) for 4 h and used the resulting culture medium to stimulate human umbilical vein endothelial cells (HUVECs). HUVECs were also simultaneously treated with hydrophilic concentrates of BHT, SNT or XBT. We evaluated the mRNA and protein expression levels of IL6, IL8, MCP-1, ICAM-1, and ELAM-1 and the activity of caspase 3/7, a marker of cell apoptosis, after stimulation and treatment. In addition, we stimulated cannulated veins from human umbilical cords for 24 h and treated them with BHT, SNT or XBT. Immunohistochemistry visualized expression of ICAM-1 and ELAM-1. RESULTS: The mRNA and protein levels of IL6, IL8, ICAM-1, and ELAM-1 were higher in stimulated HUVECs than in controls. Treating stimulated HUVECs with BHT, SNT or XBT induced an additional increase in IL6 (13- to 132-fold) and IL8 (17- to 32-fold) mRNA levels but did not influence their protein levels. In addition, BHT induced an additional increase in ICAM-1 mRNA (9-fold) expression, whereas XBT increased the mRNA and protein levels of ELAM-1 by 42-fold and 10-fold, respectively. Finally, caspase 3/7 levels, and therefore apoptosis, were up to 100% lower in cells treated with BHT than in the stimulated control (P < 0.001). CONCLUSION: The results of this study indicate that BHT, SNT, and XBT interfere in inflammatory pathways during septic processes by reducing the apoptotic effects of LPS and modifying the endothelial expression of pro-inflammatory cytokines and surface adhesion molecules.

Comparative study of regenerative effects of mesenchymal stem cells derived from placental amnion, chorion and umbilical cord on dermal wounds.

OBJECTIVE: Mesenchymal stem/stromal cells derived from human term placentas (PMSCs) are novel therapeutic agents and more topical than ever. Here we evaluated the effects of three types of PMSCs on wound healing in an in vivo mouse model: Amnion-derived MSCs (AMSCs), blood vessel-derived MSCs (BV-MSCs) from the chorionic plate and Wharton's jelly-derived MSCs (WJ-MSCs) from the umbilical cord. METHODS: We topically applied PMSCs onto skin wounds in mice using the dermal substitute Matriderm® as carrier and evaluated wound healing parameters. In addition, we investigated the effects of all PMSC types under co-application with placental endothelial cells (PLECs). After 8 days, we compared the percent of wound closure and the angiogenic potential between all groups. RESULTS: AMSCs, BV-MSCs and WJ-MSCs significantly induced a faster healing and a higher number of blood vessels in the wound when compared to controls (Matriderm®-alone). PLECs did not further improve the advantageous effects of PMSC-treatment. Quantitative data and 3D analysis by high resolution episcopic microscopy confirmed a lower density of vessels in Matriderm®/PMSCs/PLECs co-application compared to Matriderm®/PMSCs treatment. CONCLUSION: Results indicate that all three PMSC types exert similar beneficial effects on wound closure and neovascularization in our mouse model. PRACTICE: Using Matriderm® as carrier for PMSCs propagates rapid cell migration towards the wound area that allows a fast and clinically practicable method for stem cell application. IMPLICATIONS: These promising effects warrant further investigation in clinical trials.

Cell free hemoglobin in the fetoplacental circulation: a novel cause of fetal growth restriction?

Cell free hemoglobin impairs vascular function and blood flow in adult cardiovascular disease. In this study, we investigated the hypothesis that free fetal hemoglobin (fHbF) compromises vascular integrity and function in the fetoplacental circulation, contributing to the increased vascular resistance associated with fetal growth restriction (FGR). Women with normal and FGR pregnancies were recruited and their placentas collected freshly postpartum. FGR fetal capillaries showed evidence of erythrocyte vascular packing and extravasation. Fetal cord blood fHbF levels were higher in FGR than in normal pregnancies ( P < 0.05) and the elevation of fHbF in relation to heme oxygenase-1 suggests a failure of expected catabolic compensation, which occurs in adults. During ex vivo placental perfusion, pathophysiological fHbF concentrations significantly increased fetal-side microcirculatory resistance ( P < 0.05). fHbF sequestered NO in acute and chronic exposure models ( P < 0.001), and fHbF-primed placental endothelial cells developed a proinflammatory phenotype, demonstrated by activation of NF-κB pathway, generation of IL-1α and TNF-α (both P < 0.05), uncontrolled angiogenesis, and disruption of endothelial cell flow alignment. Elevated fHbF contributes to increased fetoplacental vascular resistance and impaired endothelial protection. This unrecognized mechanism for fetal compromise offers a novel insight into FGR as well as a potential explanation for associated poor fetal outcomes such as fetal demise and stillbirth.-Brook, A., Hoaksey, A., Gurung, R., Yoong, E. E. C., Sneyd, R., Baynes, G. C., Bischof, H., Jones, S., Higgins, L. E., Jones, C., Greenwood, S. L., Jones, R. L., Gram, M., Lang, I., Desoye, G., Myers, J., Schneider, H., Hansson, S. R., Crocker, I. P., Brownbill, P. Cell free hemoglobin in the fetoplacental circulation: a novel cause of fetal growth restriction?

Endothelial indoleamine 2,3-dioxygenase-1 regulates the placental vascular tone and is deficient in intrauterine growth restriction and pre-eclampsia.

Indoleamine 2,3-dioxygenase-1 (IDO1) mediates the degradation of L-tryptophan (L-Trp) and is constitutively expressed in the chorionic vascular endothelium of the human placenta with highest levels in the microvasculature. Given that endothelial expression of IDO1 has been shown to regulate vascular tone and blood pressure in mice under the condition of systemic inflammation, we asked whether IDO1 is also involved in the regulation of placental blood flow and if yes, whether this function is potentially impaired in intrauterine growth restriction (IUGR) and pre-eclampsia (PE). In the large arteries of the chorionic plate L-Trp induced relaxation only after upregulation of IDO1 using interferon gamma and tumor necrosis factor alpha. However, ex vivo placental perfusion of pre-constricted cotyledonic vasculature with L-Trp decreases the vessel back pressure without prior IDO1 induction. Further to this finding, IDO1 protein expression and activity is reduced in IUGR and PE when compared to gestational age-matched control tissue. These data suggest that L-Trp catabolism plays a role in the regulation of placental vascular tone, a finding which is potentially linked to placental and fetal growth. In this context our data suggest that IDO1 deficiency is related to the pathogenesis of IUGR and PE.

miR-146a, miR-146b, and miR-155 increase expression of IL-6 and IL-8 and support HSP10 in an In vitro sepsis model.

microRNAs (miRNAs) play an essential role in inflammation processes including sepsis. This study aimed to identify miRNAs as candidates for therapies that are involved in the innate immune response and to assess their potential functions in the activation of the endothelium. We stimulated THP-1 monocytes with 10 ng/ml LPS for 4 h and used the supernatant for the stimulation of human umbilical vein endothelial cells (HUVEC) or human pulmonary microvascular endothelial cells (HPMEC) for 16 h. miRNA array analysis (of 1,891 miRNAs) identified a 1.5-fold upregulation of miR-146a, miR-146b, and miR-155 in stimulated endothelial cells. HUVEC were transfected with miRNA inhibitors for miR-146a, miR-146b, and miR-155 to investigate the function of these miRNAs in endothelial inflammatory pathways. Inhibition of miR-146a resulted in a diminished release of interleukin (IL)-6 and IL-8 by respective 68% and 55% (P<0.001). Inhibition of miR-146b reduced the expression of IL-6 by 49% (P<0.001). Inhibition of miR-155 reduced the expression of IL-6 and IL-8 by respective 31% (P<0.001) and 14%. The inhibition of miR-146a, miR-146b, and miR-155 reduced the release of HSP10 by 50%, 35%, and 69% (P<0.05), respectively, but did not influence the expression of HSP27 or TXA2. In conclusion, miR-146a, miR-146b, and miR-155 are exerting anti-inflammatory properties by down-regulating IL-6 and IL-8, and influencing the expression of HSP10 in the activated endothelium. We provide evidence for the central role of selected miRNAs in sepsis and their use in the development of small interfering RNA therapeutics to target immune cells and sepsis pathways.

Comparison of Matrigel and Matriderm as a carrier for human amnion-derived mesenchymal stem cells in wound healing.

Amnion-derived mesenchymal stem cells (AMSC) are a promising tool in regenerative medicine. Here we evaluated the utility of Matrigel and Matriderm as carrier for the topical application of AMSC to mice skin wounds. In both application forms, AMSC promoted neovascularization of the wound area. Matrigel proved as excellent matrix for AMSC and immigrating mouse cells, but the solid Matriderm enabled a more adequate positioning of AMSC into the wound. Although AMSC did not attach to Matriderm, they reliably induced wound reduction. Thus, a combined administration of AMSC/Matriderm could be beneficial to potentiate the encouraging effects on wound healing.

Pigment epithelium-derived factor (PEDF): a novel trophoblast-derived factor limiting feto-placental angiogenesis in late pregnancy.

The rapidly expanding feto-placental vasculature needs tight control by paracrine and endocrine mechanisms. Here, we focused on paracrine influence by trophoblast, the placental epithelium. We aimed to identify differences in regulation of feto-placental angiogenesis in early versus late pregnancy. To this end, the effect of conditioned media (CM) from early and late pregnancy human trophoblast was tested on network formation, migration and proliferation of human feto-placental endothelial cells. Only CM of late pregnancy trophoblast reduced network formation and migration. Screening of trophoblast transcriptome for anti-angiogenic candidates identified pigment epithelium-derived factor (PEDF) with higher expression and protein secretion in late pregnancy trophoblast. Addition of a PEDF-neutralizing antibody restored the anti-angiogenic effect of CM from late pregnancy trophoblast. Notably, human recombinant PEDF reduced network formation only in combination with VEGF. Also in the CAM assay, the combination of PEDF with VEGF reduced branching of vessels below control levels. Analysis of phosphorylation of ERK1/2 and FAK, two key players in VEGF-induced proliferation and migration, revealed that PEDF altered VEGF signaling, while PEDF alone did not affect phosphorylation of ERK1/2 and FAK. These data suggest that the trophoblast-derived anti-angiogenic molecule PEDF is involved in restricting growth and expansion of the feto-placental endothelium predominantly in late pregnancy and targets to modulate the intracellular effect of VEGF.

Arterial endothelial cytokines guide extravillous trophoblast invasion towards spiral arteries; an in-vitro study with the trophoblast cell line ACH-3P and female non-uterine endothelial cells.

INTRODUCTION: Invasion of extravillous trophoblasts (EVT) is tightly linked to appropriate cell to cell contact as well as paracrine guidance of EVT by maternal uterine cells, conducted by a variety of locally expressed cytokines. Here we investigated the interaction of the first trimester trophoblast cell line ACH-3P with adult iliac arterial (AEC) and venous endothelial cells (VEC). METHODS: The impact of ACH-3P conditioned medium (Cdm), obtained at 2.5% and 21% oxygen, on endothelial cell viability (LDH-Assay) and network formation (Matrigel-Assay) was tested. We investigated cytokine expression of AEC- and VEC-Cdm and confirmed results with ELISA analysis, and investigated the influence of Cdm on ACH-3P proliferation and invasion. Additionally, direct co-culture experiments with ACH-3P and AEC on Matrigel were performed. A subset of experiments was verified with primary trophoblasts as well as with first trimester placenta in situ specimens. RESULTS: ACH-3P-Cdm significantly enhanced cell viability of AEC and VEC after 72 h. ACH-3P-Cdm at 2.5% oxygen stabilized endothelial network structures in Matrigel up to 24 h, similar to the effect of a direct co-culture of AEC and ACH-3P. AEC and VEC showed a similar pattern of secreted cytokines. However, elevated levels of cytokines secreted by AEC were found for GRO, IL-6, MMP-1 and uPAR. ELISA confirmed elevated concentrations of IL-6 and uPAR in AEC compared to VEC. ACH-3P and primary trophoblasts more likely invaded towards AEC-Cdm than towards VEC-Cdm. Addition of IL-6 to Cdm increased the invasion potential of both cell types. AEC- and VEC-Cdm reduced ACH-3P cell proliferation after 24 h of culture. IL-6 was highly expressed in uterine AEC compared to VEC as visualized by immunohistochemistry. DISCUSSION: The presented results clearly demonstrate that cytokines of both cell types, AEC and trophoblasts, differentially contribute to successful guidance and interaction in the process of trophoblast invasion.

Post-transcriptional down regulation of ICAM-1 in feto-placental endothelium in GDM.

Maternal gestational diabetes (GDM) is associated with hyperglycaemia and hyperinsulinemia in the fetal circulation which consequently may induce endothelial dysfunction in the feto-placental vasculature. In fact, feto-placental vasculature reveals various morphological changes in response to GDM. The cell adhesion molecules (CAMs) ICAM-1, VCAM-1 and E-selectin promote attachment and trans-endothelial migration of leukocytes, and are up regulated in inflammation and endothelial dysfunction. Thus, we hypothesized that the GDM environment upregulates ICAM-1, VCAM-1 and E-selectin in the feto-placental endothelium. We isolated primary feto-placental endothelial cells (fpEC) after normal (n=18) and GDM pregnancy (n=11) and analyzed mRNA (RT-qPCR) and protein expression (Immunoblot) of ICAM-1, VCAM-1 and E-selectin. While other CAMs were unchanged on mRNA and protein levels, ICAM-1 protein was decreased by GDM. Further analysis revealed also a decrease in the release of soluble ICAM-1 (sICAM-1), whose levels correlated negatively with maternal BMI. We conclude that this reduction of ICAM-1 protein species is the result of post-translational regulation, since ICAM-1 mRNA expression was unchanged. In fact, miRNAs targeting ICAM-1 were upregulated in GDM fpEC. Immunohistochemistry showed weaker ICAM-1 staining in the placental endothelium after GDM pregnancies, and demonstrated ICAM-1 binding partners CD11a and CD18 expressed on leukocytes in fetal circulation and on placental tissue macrophages. This study identified reduction of ICAM-1 protein in fpEC in GDM pregnancy, which was regulated post-transcriptionally. Low ICAM-1 protein production may represent a protective, placenta-specific mechanism to avoid leukocyte transmigration into the placenta in response to GDM.

Dysregulated flow-mediated vasodilatation in the human placenta in fetal growth restriction.

Increased vascular resistance and reduced fetoplacental blood flow are putative aetiologies in the pathogenesis of fetal growth restriction (FGR); however, the regulating sites and mechanisms remain unclear. We hypothesised that placental vessels dictate fetoplacental resistance and in FGR exhibit endothelial dysfunction and reduced flow-mediated vasodilatation (FMVD). Resistance was measured in normal pregnancies (n = 10) and FGR (n = 10) both in vivo by umbilical artery Doppler velocimetry and ex vivo by dual placental perfusion. Ex vivo FMVD is the reduction in fetal-side inflow hydrostatic pressure (FIHP) following increased flow rate. Results demonstrated a significant correlation between vascular resistance measured in vivo and ex vivo in normal pregnancy, but not in FGR. In perfused FGR placentas, vascular resistance was significantly elevated compared to normal placentas (58 ± 7.7 mmHg and 36.8 ± 4.5 mmHg, respectively; 8 ml min(-1) ; means ± SEM; P < 0.0001) and FMVD was severely reduced (3.9 ± 1.3% and 9.1 ± 1.2%, respectively). In normal pregnancies only, the highest level of ex vivo FMVD was associated with the lowest in vivo resistance. Inhibition of NO synthesis during perfusion (100 µm l-NNA) moderately elevated FIHP in the normal group, but substantially in the FGR group. Human placenta artery endothelial cells from FGR groups exhibited increased shear stress-induced NO generation, iNOS expression and eNOS expression compared with normal groups. In conclusion, fetoplacental resistance is determined by placental vessels, and is increased in FGR. The latter also exhibit reduced FMVD, but with a partial compensatory increased NO generation capacity. The data support our hypothesis, which highlights the importance of FMVD regulation in normal and dysfunctional placentation.

A role for GPR55 in human placental venous endothelial cells.

Endocannabinoids and their G protein-coupled receptors have been suggested to play a key role in human pregnancy, by regulating important aspects such as implantation, decidualization, placentation and labor. G protein-coupled receptor 55 (GPR55) was previously postulated to be another cannabinoid receptor, since specific cannabinoids were shown to act independently of the classical cannabinoid receptors CB1 or CB2. Current knowledge about GPR55 expression and function in human placenta is very limited and motivated us to evaluate human placental GPR55 expression in relation to other human peripheral tissues and to analyze spatiotemporal GPR55 expression in human placenta. Gene expression analysis revealed low GPR55 levels in human placenta, when compared to spleen and lung, the organs showing highest GPR55 expression. Moreover, expression analysis showed 5.8 fold increased placental GPR55 expression at term compared to first trimester. Immunohistochemistry located GPR55 solely at the fetal endothelium of first trimester and term placentas. qPCR and immunocytochemistry consistently confirmed GPR55 expression in isolated primary placental arterial and venous endothelial cells. Incubation with L-α-lysophosphatidylinositol (LPI), the specific and functional ligand for GPR55, at a concentration of 1 µM, significantly enhanced migration of venous, but not arterial endothelial cells. LPI-enhanced migration was inhibited by the GPR55 antagonist O-1918, suggesting a role of the LPI-GPR55 axis in placental venous endothelium function.

Placental mesenchymal stromal cells derived from blood vessels or avascular tissues: what is the better choice to support endothelial cell function?

Mesenchymal stromal cells (MSCs) are promising tools for therapeutic revascularization of ischemic tissues and for support of vessel formation in engineered tissue constructs. Recently, we could show that avascular-derived MSCs from placental amnion release soluble factors that exhibit survival-enhancing effects on endothelial cells (ECs). We hypothesize that MSCs derived from placental blood vessels might have even more potent angiogenic effects. Therefore, we isolated and characterized MSCs from placental chorionic blood vessels (bv-MSCs) and tested their angiogenic potential in comparison to amnion-derived avascular MSCs (av-MSCs). bv-MSCs express a very similar surface marker profile compared with av-MSCs and could be differentiated toward the adipogenic and osteogenic lineages. bv-MSCs exert immunosuppressive properties on peripheral blood mononuclear cells, suggesting that they are suitable for cell transplantation settings. Conditioned medium (Cdm) from av-MSCs and bv-MSCs significantly enhanced EC viability, whereas only Cdm from bv-MSCs significantly increased EC migration and network formation (Matrigel assay). Angiogenesis array analysis of av- and bv-MSC-Cdm revealed a similar secretion pattern of angiogenic factors, including angiogenin, interleukins-6 and -8, and tissue inhibitors of matrix metalloproteinase-1 and 2. Enzyme-linked immunosorbent assay analysis showed that, in contrast to av-MSCs, bv-MSCs secreted vascular endothelial growth factor. In direct coculture with bv-MSCs, ECs showed a significantly increased formation of vessel-like structures compared with av-MSCs. With regard to therapeutic treatment, bv-MSCs and particularly their Cdm might be valuable to stimulate angiogenesis especially in ischemic tissues. av-MSCs and their Cdm could be beneficial in conditions when it is required to promote the survival and stabilization of blood vessels without the risk of unmeant angiogenesis.

Amnion-derived mesenchymal stromal cells show a mesenchymal-epithelial phenotype in culture.

The amnionic membrane is a rich source of multipotent mesenchymal stromal cells (hAMSC), which are readily available and show a potential use in regenerative medicine and tissue engineering. Before these cells can be applied clinically, careful characterization is necessary, especially as primary cells are known to change their phenotype in culture. We analyzed the mesenchymal phenotype of hAMSC at different stages after isolation using immunohistochemistry. Shortly after isolation (1 day), 92 % (± 7 %) of the hAMSC expressed the mesenchymal marker vimentin, 2 % (± 1 %) stained for the epithelial marker cytokeratin-7 and 5 % (± 4 %) co-expressed these markers. After 5 days, the double positive cells slightly increased to 7 % (± 3 %), while exclusive expression of cytokeratin-7 or vimentin remained unchanged (1 % ± 2 % and 92 % ± 1 %, respectively). After the first passage, all attached cells were vimentin-positive, while 54 % (± 9 %) co-expressed cytokeratin-7 and vimentin. Thus, we conclude that under culture, hAMSC adopt a hybrid mesenchymal-epithelial phenotype. It is also essential to perform microscopical examination during the first days after isolation to detect contaminations with human amnion-derived epithelial cells in cultures of hAMSC.

Phospholipid transfer protein is expressed in cerebrovascular endothelial cells and involved in high density lipoprotein biogenesis and remodeling at the blood-brain barrier.

Phospholipid transfer protein (PLTP) is a key protein involved in biogenesis and remodeling of plasma HDL. Several neuroprotective properties have been ascribed to HDL. We reported earlier that liver X receptor (LXR) activation promotes cellular cholesterol efflux and formation of HDL-like particles in an established in vitro model of the blood-brain barrier (BBB) consisting of primary porcine brain capillary endothelial cells (pBCEC). Here, we report PLTP synthesis, regulation, and its key role in HDL metabolism at the BBB. We demonstrate that PLTP is highly expressed and secreted by pBCEC. In a polarized in vitro model mimicking the BBB, pBCEC secreted phospholipid-transfer active PLTP preferentially to the basolateral ("brain parenchymal") compartment. PLTP expression levels and phospholipid transfer activity were enhanced (up to 2.5-fold) by LXR activation using 24(S)-hydroxycholesterol (a cerebral cholesterol metabolite) or TO901317 (a synthetic LXR agonist). TO901317 administration elevated PLTP activity in BCEC from C57/BL6 mice. Preincubation of HDL3 with human plasma-derived active PLTP resulted in the formation of smaller and larger HDL particles and enhanced the capacity of the generated HDL particles to remove cholesterol from pBCEC by up to 3-fold. Pre-ß-HDL, detected by two-dimensional crossed immunoelectrophoresis, was generated from HDL3 in pBCEC-derived supernatants, and their generation was markedly enhanced (1.9-fold) upon LXR activation. Furthermore, RNA interference-mediated PLTP silencing (up to 75%) reduced both apoA-I-dependent (67%) and HDL3-dependent (30%) cholesterol efflux from pBCEC. Based on these findings, we propose that PLTP is actively involved in lipid transfer, cholesterol efflux, HDL genesis, and remodeling at the BBB.

Soluble factors of amnion-derived cells in treatment of inflammatory and fibrotic pathologies.

Inflammation is a complex defense mechanism characterized by leukocyte migration from the vasculature into damaged tissues and subsequent deposition of extracellular matrix resulting in tissue repair. The inflammatory process is generally categorized into an acute, rapid response, and a persistent but slowly evolving chronic condition, which may progress into inflammatory diseases. An excessive deposition of extracellular matrix leads to overgrowth, hardening, and/or scarring of tissues, defined as fibrosis. The amnion has been used as biomaterial in medicine for over 100 years and has been proven valuable for the treatment of different pathological conditions including wound healing. In light of recent reports, this article will review the effects of the amnion and its cellular components within the inflammatory-fibrotic scenario and the factors described so far that could be involved in these immunomodulatory actions. As proof of principles, we will also discuss pre-clinical and clinical applications of the amnion where advantage has been taken of its anti-inflammatory and anti-fibrotic properties. It is conceivable that the local host environment in which the amnion is placed may have a profound role in influencing the production and function of soluble factors and the shift towards different steps in triggering healing. The healing effect depends on time, dosage, and location of cytokine/growth factor production by the amnion, together with the influence of the host microenvironment. Indeed, determining the specific cascade of events that may define the role of the amnion in a given clinical situation remains a challenge.