Recovery Of Endothelial Cells Research Articles

Micro(RNA)managing Endothelial Regeneration

Systemic targeting of miR-126 production might be useful in treating atherosclerosis.

Distinct CD11b+-monocyte subsets accelerate endothelial cell recovery after acute and chronic endothelial cell damage

BackgroundEndothelial cell recovery requires replenishment of primary cells from the endothelial lineage. However, recent evidence suggests that cells of the innate immune system enhance endothelial regeneration. Methods and resultsFocusing on mature CD11b+-monocytes, we analyzed the fate and the effect of transfused CD11b+-monocytes after endothelial injury in vivo. CD11b-diphtheria-toxin-receptor-mice – a mouse model in which administration of diphtheria toxin selectively eliminates endogenous monocytes and macrophages – were treated with WT-derived CD11b+-monocytes from age-matched mice. CD11b+-monocytes improved endothelium-dependent vasoreactivity after 7days while transfusion of WT-derived CD11b−-cells had no beneficial effect on endothelial function. In ApoE−/−-CD11b-DTR-mice with a hypercholesterolemia-induced chronic endothelial injury transfusion of WT-derived CD11b+-monocytes stimulated by interferon-γ (IFNγ) decreased endothelial function, whereas interleukin-4-stimulated (IL4) monocytes had no detectable effect on vascular function. Bioluminescent imaging revealed restriction of transfused CD11b+-monocytes to the endothelial injury site in CD11b-DTR-mice depleted of endogenous monocytes. In vitro co-culture experiments revealed significantly enhanced regeneration properties of human endothelial outgrowth cells (EOCs) when cultured with preconditioned-media (PCM) or monocytes of IL4-stimulated-subsets compared to the effects of IFNγ-stimulated monocytes. ConclusionCD11b+-monocytes play an important role in endothelial cell recovery after endothelial injury by homing to the site of vascular injury, enhancing reendothelialization and improving endothelial function. In vitro experiments suggest that IL4-stimulated monocytes enhance EOC regeneration properties most likely by paracrine induction of proliferation and cellular promotion of differentiation. These results underline novel insights in the biology of endothelial regeneration and provide additional information for the treatment of vascular dysfunction.

The expression and proangiogenic effect of nucleolin during the recovery of heat-denatured HUVECs

BackgroundThe present study aims to examine the expression patterns and roles of nucleolin during the recovery of heat-denatured human umbilical vein endothelial cells (HUVECs). MethodsDeep partial thickness burn model in Sprague–Dawley rats and the heat denatured cell model (52°C, 35s) were used. The expression of nucleolin was measured using Western blot analysis and real-time PCR. Angiogenesis was assessed using in vitro parameters including endothelial cell proliferation, transwell migration assay, and scratched wound healing. Gene transfection and RNA interference approaches were employed to investigate the roles of nucleolin. ResultsNucleolin mRNA and protein expression showed a time-dependent increase during the recovery of heat-denatured dermis and HUVECs. Heat-denaturation time-dependently promoted cell growth, adhesion, migration, scratched wound healing and formation of tube-like structures in HUVECs. These effects of heat denaturation on endothelial wound healing and formation of tube-like structures were prevented by knockdown of nucleolin, whereas over-expression of nucleolin increased cell growth, migration, and formation of tube-like structures in cultured HUVEC endothelial cells. In addition, we found that the expression of vascular endothelial growth factor (VEGF) increased during the recovery of heat-denatured dermis and HUVECs, and nucleolin up-regulated VEGF in HUVECs. ConclusionsThe present study reveals that the expression of nucleolin is up-regulated, and plays a pro-angiogenic role during the recovery of heat-denatured dermis and its mechanism is probably dependent on production of VEGF. General significanceWe find a novel and important pro-angiogenic role of nucleolin during the recovery of heat-denatured dermis.

Endothelial barrier disruption and recovery is controlled by substrate stiffness

Circulating barrier disruptive agonists bind specific cell membrane receptors and trigger signal transduction pathways leading to the activation of cell contractility and endothelial cell (EC) permeability. Although all cells in tissues including vascular EC are surrounded by compliant extracellular matrix, the impact of matrix stiffness on agonist-induced signaling, cytoskeletal remodeling and EC barrier regulation is not well understood. This study examined agonist-induced cytoskeletal and signaling changes associated with EC barrier disruption and recovery using pulmonary EC grown on compliant substrates of physiologically relevant (8.6kPa) stiffness, very low (0.55kPa) and very high (42kPa) stiffness. Human pulmonary microvascular and macrovascular EC grown on 0.55kPa substrate contained a few actin stress fibers, while stress fiber amount increased with increasing matrix stiffness. Thrombin-induced stress fiber formation was maximal in EC grown on 42kPa substrate, diminished on 8.6kPa substrate, and was minimal on 0.55kPa substrate. These effects were linked to a stiffness-dependent increase in thrombin-induced phosphorylation of the Rho kinase target, myosin light chain phosphatase (MYPT1), and regulatory myosin light chains (MLC). Surprisingly, EC barrier recovery and activation of Rac GTPase-dependent barrier protective signaling reached maximal levels in EC grown on 8.6kPa, but not on 0.55kPa substrate. In conclusion, these data show a critical role of extracellular matrix stiffness in the regulation of the Rac/Rho signaling balance during onset and resolution of agonist-induced EC permeability. The optimal conditions for the Rho/Rac signaling switch, which provides an effective and reversible EC cytoskeletal and permeability response to agonist, are reached in cells grown on the matrix of physiologically relevant stiffness.

The Use of Fiber-Reinforced Scaffolds Cocultured with Schwann Cells and Vascular Endothelial Cells to Repair Rabbit Sciatic Nerve Defect with Vascularization

To explore the feasibility of biodegradable fiber-reinforced 3D scaffolds with satisfactory mechanical properties for the repair of long-distance sciatic nerve defect in rabbits and effects of vascularized graft in early stage on the recovery of neurological function, Schwann cells and vascular endothelial cells were cocultured in the fiber-reinforced 3D scaffolds. Experiment group which used prevascularized nerve complex for the repair of sciatic nerve defect and control group which only cultured with Schwann cells were set. The animals in both groups underwent electromyography to show the status of the neurological function recovery at 4, 8, and 16 weeks after the surgery. Sciatic nerve regeneration and myelination were observed under the light microscope and electron microscope. Myelin sheath thickness, axonal diameter, and number of myelinated nerve fiber were quantitatively analyzed using image analysis system. The recovery of foot ulcer, the velocity of nerve conduction, the number of regenerating nerve fiber, and the recovery of ultrastructure were increased in the experimental group than those in the control group. Prevascularized tissue engineered fiber-reinforced 3D scaffolds for the repair of sciatic nerve defects in rabbits can effectively promote the recovery of neurological function.

Recovery of Senescent Endothelial Cells From Injury

Percutaneous coronary intervention is increasingly performed in elderly patients. Because the procedure is associated with endothelial cell (EC) denudation, we compared recovery of young and old ECs from scratch injuries inflicted in culture. Although senescent ECs displayed markedly reduced potential to proliferate and migrate, they repopulated the wounds as fast as young cells. Morphometric analysis revealed that senescent cells were significantly larger and as a result far fewer senescent cells managed to cover the lesion. Compared with young EC, senescent cells displayed increased expression of senescence-associated β-galactosidase, nitric oxide synthase (eNOS), and AKT kinase, and secreted increased amounts of growth factors (VEGF, TGF-β), cytokines (IL-6, IL-8, MCP-1), adhesion molecules (sICAM-1), and matrix proteins (fibronectin). This secretory phenotype rather than the rate of wound closure per se may contribute to unfavorable vascular remodeling in the elderly undergoing coronary catheterization.

Infusion of Endothelial Progenitor Cells Accelerates Hematopoietic and Immune Reconstitution, and Ameliorates the Graft-Versus-Host Disease After Hematopoietic Stem Cell Transplantation

Hematopoietic stem cells transplantation (HSCT) causes endothelial cell damage, disrupting hematopoietic microenviroment and leading to various complications. We hypothesized that infusion of endothelial progenitor cells (EPCs) may improve endothelium repair, facilitate hematopoietic reconstitution, and alleviate complications associated with HSCT. C57Bl6, and BALB/c mice received total body irradiation followed by infusion of C57Bl6-derived bone marrow (BM) cells, with or without concomitant infusion of C57Bl6-derived EPCs. The time course of hematopoietic and immune reconstitution and the severity of the graft-versus-host disease (GVHD) were monitored. Further, to confirm that EPCs promote endothelial cell recovery, HSCT mice were treated with anti-VE-cadherin antibody targeting the endothelium. The EPCs-treated mice exhibited accelerated recovery of BM vasculature, cellularity, hematopoietic stem and progenitor cell recovery, improved counts of lymphocyte subsets in peripheral blood, and facilitated spleen structure reconstruction. EPCs infusion also ameliorated the GVHD in the C57Bl6 → BALB/c allo-HSCT model. Systemic administration of anti-VE-cadherin antibody significantly delayed hematological and immune reconstitution in the EPCs-infused mice. In conclusion, our data demonstrate that infusion of EPCs augments the hematopoietic and immune reconstitution, and alleviates the GVHD. These findings further highlight the relationship between the microvascular recovery, hematopoietic and immune reconstitution, and the GVHD.

AS-154 IVUS Assessment of Chitosan/Heparin Layer-by-Layer Self Assembly Coating Stent on Late Stent Malappoisition and Vessel Remodeling in Porcine Model

First generation drug-eluting stent(DES) was coated with permanent polymer. Current DES was blamed of vessel wall inflammatory and late in-stent thrombosis. With excellent biocompatibility and property of promoting endothelial cell recovery, chitosan and heparin layer-by-layer coating may be an alternation.

Estrogen-like activity and dual roles in cell signaling of an Agaricus blazei Murrill mycelia-dikaryon extract

Agaricus blazei (A. blazei) Murrill mycelia-dikaryon has attracted the attention of scientists and clinicians worldwide owing to its potential for the treatment of cancer. However, little is known about its effect on other pathologies. This study sought to extend the potential medical usefulness of A. blazei for preventing vascular damage and to unravel its mechanism of action. The A. blazei extract showed estrogen-like activity in both gene expression profiling and a luciferase assay. Indeed, the extract inhibited oxidized low-density lipoprotein-stimulated activation of Erk1/2, Akt and p38 in HUVECs and macrophage-derived TIB-67 cells. Moreover, the extract enhanced transcription of the glutathione peroxidase 3 (GPX3), α-synuclein (SNCA) and endothelial nitrogen-oxide synthase (eNOS) genes. Furthermore, atherosclerotic lesions in rabbits were reduced by intake of A. blazei powder. Therefore, A. blazei may be useful for preventing atherosclerosis via dual roles in cell signaling, suppression of macrophage development and the recovery of endothelial cells from vascular damage.

Precise Scheduling of Chemotherapy Primes VEGF-producing Tumors for Successful Systemic Oncolytic Virotherapy

We have previously reported that a burst of vascular endothelial growth factor (VEGF) signaling to tumor-associated endothelium induces a proviral state, during which systemically delivered oncolytic reovirus can replicate in endothelium, thereby inducing immune-mediated vascular collapse and significant antitumor therapy. Using chimeric receptors, we show here that induction of the proviral state proceeds through VEGFR2, but not VEGFR1, signaling in endothelial cells. In contrast, innate immune activation by reovirus-exposed endothelial cells was predominantly through VEGFR1. By screening conventional chemotherapies for their ability to induce similar effects in combination with reovirus both in vitro and in vivo, we observed that the proviral state could also be induced in endothelial cells exposed to VEGF during rebound from paclitaxel-mediated inhibition of VEGF signaling. We translated these in vitro findings in vivo by careful scheduling of paclitaxel chemotherapy with systemic virotherapy, neither of which alone had therapeutic effects against B16 tumors. Systemic availability of reovirus during endothelial cell recovery from paclitaxel treatment allowed for endothelial replication of the virus, immune-mediated therapy, and tumor cures. Therefore, careful scheduling of combination viro- and chemotherapies, which preclinical testing suggests are individually ineffective against tumor cells, can lead to rational new clinical protocols for systemic treatments with oncolytic viruses.

Gammaherpesvirus 68 Infection of Endothelial Cells Requires both Host Autophagy Genes and Viral Oncogenes for Optimal Survival and Persistence

Gammaherpesvirus-associated neoplasms include tumors of lymphocytes, epithelial cells, and endothelial cells (ECs). We previously showed that, unlike most cell types, ECs survive productive gammaherpesvirus 68 (γHV68) infection and achieve anchorage-independent growth, providing a cellular reservoir for viral persistence. Here, we demonstrated autophagy in infected ECs by analysis of LC3 localization and protein modification and that infected ECs progress through the autophagosome pathway by LC3 dual fluorescence and p62 analysis. We demonstrate that pharmacologic autophagy induction results in increased survival of infected ECs and, conversely, that autophagy inhibition results in death of infected EC survivors. Furthermore, we identified two viral oncogenes, v-cyclin and v-Bcl2, that are critical to EC survival and that modify EC proliferation and survival during infection-induced autophagy. We found that these viral oncogenes can also facilitate survival of substrate detachment in the absence of viral infection. Autophagy affords cells the opportunity to recover from stressful conditions, and consistent with this, the altered phenotype of surviving infected ECs was reversible. Finally, we demonstrated that knockdown of critical autophagy genes completely abrogated EC survival. This study reveals a viral mechanism which usurps the autophagic machinery to promote viral persistence within nonadherent ECs, with the potential for recovery of infected ECs at a distant site upon disruption of virus replication.

Functional restoration of endothelial cells of the cryopreserved heart valve

Although several approaches have been tried to improve the durability of cryopreserved valves, cellular restoration after thawing remains to be investigated. The aim of our study was to assess the functional restoration of endothelial cells of cryopreserved heart valves by in vitro culture for an alternative step to improving longevity. Cryopreserved human umbilical vein endothelial cells (HUVECs) and porcine aortic cusps were cultivated for 14 days after thawing. Then the cellular activity of the enzymes cytosolic esterase and mitochondrial dehydrogenase was measured. The cellular viability of cryopreserved cusps was also assessed using confocal laser scanning microscopy. The number of viable HUVECs decreased markedly after cryopreservation and thawing but recovered to pre-cryopreservation level after 14 days of culture. In contrast, the enzyme activity of the cryopreserved porcine aortic cusps showed recovery at 7 days of in vitro tissue culture after thawing. Confocal laser scanning microscopy findings showed that the cellular cytosolic esterase activity of cryopreserved cusps deteriorated after thawing but displayed considerable recovery by day 14 of culture. The functional recovery of endothelial cells in cryopreserved heart valves seems to require tissue culture of at least 14 days. Ex vivo endothelial restoration of cryopreserved heart valves may add to heart valve durability.

Cultivation and recovery of vascular endothelial cells in microchannels of a separable micro-chemical chip

Various micro cell culture systems have recently been developed. However, it is extremely difficult to recover cultured cells from a microchannel because the upper and lower substrates of a microchip are permanently combined. Therefore, we developed a cell culture and recovery system that uses a separable microchip with reversible combining that allows separation between closed and open channels. To realize this system, two problems related to microfluidic control—prevention of leakage and non-invasive recovery of cultured cells from the substrate—must be overcome. In the present study, we used surface chemistry modification to solve both problems. First, octadecyltrimethoxysilane (ODTMS) was utilized to control the Laplace pressure at the liquid/vapor phase interface, such that it was directed toward the microchannels, which suppressed leakage from the slight gap between two substrates. Second, a thermoresponsive polymer poly( N-isopropyl acrylamide) (PNIPAAm) was used to coat the surface of the ODTMS-modified microchannel by UV-mediated photopolymerization. PNIPAAm substrates are well known for controlled cell adhesion/detachment by alteration of temperature. Finally, the ODTMS- and PNIPAAm-modified separable microchips were subjected to patterning, and human arterial endothelial cells (HAECs) were cultured in the resulting microchannels with no leakage. After 96 h of the culture, the HAECs were detached from the microchips by decreasing the temperature and were then recovered from the microchannels. This study is the first to demonstrate the recovery of living cells cultured in a microchannel, and may be useful as a fundamental technique for vascular tissue engineering.

Enhanced Endothelialization on Surface Modified Poly(l-Lactic Acid) Substrates

Improved biodegradable vascular grafts and stents are in demand, particularly for pediatric patients. Poly(L-lactic acid) (PLLA) is an FDA-approved biodegradable polymer of potential use for such applications. However, tissue culture studies have shown that endothelial cell (EC) attachment and growth occurs relatively slowly on PLLA surfaces. This slow growth has been attributed to the fact that PLLA represents a hydrophobic substrate, relatively devoid of active functional groups. As a result, the slow EC recovery on the luminal side of PLLA stents provides an increased risk of induced thrombosis. In the present study, surface modification of PLLA substrates has been examined as a potential route to enhance EC growth. For this purpose, PLLA surfaces were modified via pulsed plasma deposition of thin films of poly(vinylacetic acid). The -COOH surface groups, introduced by the plasma deposition, were employed to conjugate fibronectin (FN), followed by attachment of vascular endothelial growth factor to FN. Pig Aorta ECs (PAE) and kinase-insert domain-containing receptor (KDR)-transfected PAE showed increased cell adhesion and proliferation, as well as substantially improved cell retention under fluidic shear stress on surface-modified PLLA compared with untreated PLLA. Although KDR-transfected PAE exhibited better cell proliferation than PAE, normal EC functions, including EC morphology, nitric oxide production, and KDR expression, were observed when cells were grown on surface-modified PLLA. The results obtained clearly indicate that this combined surface modification technique using poly(vinylacetic acid) deposition, FN conjugation, and vascular endothelial growth factor surface delivery can enhance endothelialization on PLLA, particularly when employed in conjunction with the growth of KDR-transfected ECs.

Adipose Stem Cell Treatment in Mice Attenuates Lung and Systemic Injury Induced by Cigarette Smoking

Adipose-derived stem cells express multiple growth factors that inhibit endothelial cell apoptosis, and demonstrate substantial pulmonary trapping after intravascular delivery. We hypothesized that adipose stem cells would ameliorate chronic lung injury associated with endothelial cell apoptosis, such as that occurring in emphysema. Therapeutic effects of systemically delivered human or mouse adult adipose stem cells were evaluated in murine models of emphysema induced by chronic exposure to cigarette smoke or by inhibition of vascular endothelial growth factor receptors. Adipose stem cells were detectable in the parenchyma and large airways of lungs up to 21 days after injection. Adipose stem cell treatment was associated with reduced inflammatory infiltration in response to cigarette smoke exposure, and markedly decreased lung cell death and airspace enlargement in both models of emphysema. Remarkably, therapeutic results of adipose stem cells extended beyond lung protection by rescuing the suppressive effects of cigarette smoke on bone marrow hematopoietic progenitor cell function, and by restoring weight loss sustained by mice during cigarette smoke exposure. Pulmonary vascular protective effects of adipose stem cells were recapitulated by application of cell-free conditioned medium, which improved lung endothelial cell repair and recovery in a wound injury repair model and antagonized effects of cigarette smoke in vitro. These results suggest a useful therapeutic effect of adipose stem cells on both lung and systemic injury induced by cigarette smoke, and implicate a lung vascular protective function of adipose stem cell derived paracrine factors.

A Simplified Method for Quantifying Cell Migration/Wound Healing in 96-Well Plates

Cell migration plays a key role in both normal physiological and pathological conditions. The study of cell migration and its underlying mechanisms is of great significance in various fields of research, including basic biology and pharmaceutical development. The cell migration or scratch wounding assay is an easy and economical in vitro method that allows researchers to assess a large number of testing compounds. Even though this simple assay has been used for decades, researchers are still trying to modify such experimental protocols and wounding devices. In this study, an 8-channel mechanical "wounder" was designed for performing a cell migration assay, particularly in a 96-well culture plate format. With special designs of a guiding bar and adjustable pins for use with disposable pipette tips, this wounder confined the scratch area within the center of each well to ensure a perfect contact between the pins and the well surface. As a result, this mechanical wounder produces a uniform denudation of a cell monolayer in a 96-well plate with a wound size of around 600 microm. Using this improved wounding device, the effects of epidermal growth factor and DL-alpha-difluoromethylornithine on the reepithelialization of rat intestinal epithelial cells (IEC-6) and serum on the wound recovery of human umbilical vein endothelial cells were demonstrated. This wounder facilitates cell migration study and can be applicable for multiple sample analysis.

Myeloablative Therapies Damage and Alter the Composition of the Cells of the Bone Marrow Microenvironment.

Abstract 1447Poster Board I-470Patients with a range of blood cell diseases are usually treated with myeloablative therapies such as chemotherapy or irradiation accompanied by bone marrow (BM) transplants. These therapies have severe effects on the hematopoietic system and cause prolonged pancytopenia, which is life-threatening to the patient. The effects of myeloablative therapies on hematopoietic cells are well-documented but their impacts on the cells of the BM microenvironment, which have important roles in regulating hematopoiesis, are largely unknown. Using the mouse model, we have analyzed the effects of 11 Gy irradiation and transplantation of 5 × 106 BM cells/mouse on hematopoietic and BM microenvironment cells: osteoblasts (Obs), endothelial cells (ECs) (both which have been shown to be important positive regulators of hematopoiesis) and adipocytes (known negative regulators of hematopoiesis). Mature and immature hematopoietic cell contents in BM, peripheral blood and spleen were assessed by cell counts together with fluorescence-activated cell-sorting (FACS) analysis and colony-forming cell potential. BM microenvironment Ob and adipocyte cell content were examined by standard histomorphometry methods on non-decalcified plastic-embedded tibiae. BM microenvironment ECs were measured by immunohistochemical staining of paraffin-embedded sections accompanied by FACS-analysis of lineage/CD45/CD48-negative, CD31-positive cells. Quantitative real-time PCR of BM provided further insight into changes in transcripts specific for immature populations of BM microenvironment cells post-transplant. Cohorts of male mice were analyzed at numerous time-points corresponding to: age-matched non-transplanted male mice (day 0); periods of severe pancytopenia (days 2-7); early recovery of hematopoiesis (days 10-35) and the time-point at which stable hematopoiesis was re-established (day 84). The earliest change in the BM microenvironment was to ECs, as massive hemorrhaging was observed, with damaged vasculature throughout the BM cavity occurring as early as day 2 post-transplant. Furthermore, the numbers of ECs in the BM markedly dropped at this time-point, and this was accompanied by 2-fold reductions in transcripts for the BM vascular-specific markers VEGFR2 and VEGFR3. In contrast, the expression of VE-cadherin, a molecule important for endothelial cell-cell interactions, was significantly up-regulated (6-fold, P<0.05 vs day 0), potentially to aid repair of the vasculature. At the same time-point stromal cell-derived factor-1 (CXCL12), a chemokine that retains hematopoietic cells in the BM but also functions as an angiogenic factor, was highly up-regulated in BM (30-fold, P<0.001) but returned to normal levels by day 7 post-transplant. Interestingly, EC cytopenia paralleled that observed for hematopoietic cells, however, full recovery of BM ECs was detected by day 14 post-transplant. There was a significant 2-fold reduction in trabecular bone that persisted from days 7-35 post-transplant (P<0.05 vs day 0). This correlated with significant (2-fold) decreases in transcripts of Runx2 and Osterix (P<0.005 vs day 0), both markers of immature Ob precursors, Furthermore, while non-treated age-matched mice did not have significant numbers of adipocytes in their BM, there was a 20-fold increase in adipocytes visible from days 7-35 post-transplant (P<0.05). This was preceded by a significant increase in expression of the early adipocyte markers peroxisome proliferator-activated receptor-γ (PPARγ) (12-fold) and adiponectin (3-fold) in the BM by day 2 post-transplant (P<0.0005 vs day 0). These inverse changes observed in bone and adipocyte formation may help to explain why both parathyroid hormone and a PPARγ antagonist (which target mesenchymal progenitor cells to reduce adipogenesis and increase bone formation) have recently been shown to aid hematological recovery post-transplant. Preliminary results suggest that similar BM microenvironment cell changes are also observed when mice are treated with the cytotoxic drug 5-fluorouracil. In conclusion, the cells of the BM microenvironment are highly susceptible to myeloablative therapies. Treatments aiding the recovery of the different BM microenvironment cell types might in turn reduce pancytopenia and promote more rapid hematological recovery in patients receiving myeloablative therapies. DisclosuresNo relevant conflicts of interest to declare.

Endothelial cell recovery, acute thrombogenicity, and monocyte adhesion and activation on fluorinated copolymer and phosphorylcholine polymer stent coatings

This study compares the effects of two polymers currently being marketed on commercially available drug-eluting stents, PVDF-HFP fluorinated copolymer (FP) and phosphorylcholine polymer (PC), on re-endothelialization, acute thrombogenicity, and monocyte adhesion and activity. Rabbit iliac arteries were implanted with cobalt–chromium stents coated with FP or PC polymer (without drug) and assessed for endothelialization at 14 days by confocal and scanning electron microscopy (SEM). Endothelialization was equivalent and near complete for FP and PC polymer-coated stents (>80% by SEM). Acute thrombogenicity was assessed in a Chandler loop model using porcine blood. Thrombus adherence was similar for both polymers as assessed by clot weight, thrombin–antithrombin III complex, and lactate dehydrogenase expression. In vitro cell adhesion assays were performed on FP and PC polymer-coated glass coupon surfaces using HUVECs, HCAECs, and THP-1 monocytes. The number of ECs adhered to FP and control surfaces were equivalent and significantly greater than on PC surfaces ( p < 0.05). There were no differences in THP-1 monocyte adhesion and cytokine (MCP-1, RANTES, IL-6, MIP-1α, MIP-1β, G-CSF) expression. The data suggests that biological responses to both FP and PC polymer are similar, with no mechanistic indication that these polymers would be causative factors for delayed vessel healing in an acute timeframe.

Epithelial cell fate following lung injury

Lung epithelium is the primary site of lung damage in various lung diseases. Epithelial cell death has been considered to be the initial event in lung injury and is followed by remodeling processes. When the degree of lung injury is mild, damaged tissue will be repaired normally, whereas excess cell death may lead to irreparable lung damage and remodeling processes. The survival and recovery of epithelial and endothelial cells, and the resolution of inflammatory cells appear to be key for normal tissue repair. We review the recent advances in the understanding of mechanisms of cell death following lung injury in various lung diseases and discuss its regulation by novel strategies. Further understanding of mechanisms of cell death and its regulation may lead to the development of effective treatments against lung injury.

Effect of Acute Heat Stress on Heat Shock Protein 70 and Its Corresponding mRNA Expression in the Heart, Liver, and Kidney of Broilers

The objective of this study was to investigate the expression and localization of heat shock protein 70 (Hsp70) and its mRNA in the heart, liver, and kidney of acutely heat-stressed broilers at various stressing times. Male AA broilers (n = 100) were randomly divided into 5 groups of 20 birds per group. After 30 d of adaptive feeding at ambient temperature, 80 experimental broilers were suddenly heat stressed by increasing the environmental temperature from 22±1°C to 37±1°C. The 4 groups were heat stressed for 2, 3, 5, and 10 h, respectively. The localizations of Hsp70 protein and mRNA, determined by immunohistochemical staining and in situ hybridization, respectively, were demonstrated to be tissue dependent, implying that different tissues have differential sensibilities to heat stress. Intense Hsp70 staining was identified in the vascular endothelial cell of heart, liver and kidney, suggesting an association between expression of Hsp70 in vascular endothelial cell and functional recovery of blood vessels after heat shock treatment. Antemortem heat stress had a significant effect on the expression of Hsp70 protein and mRNA. The quantitation of Hsp70 protein and mRNA were both time and tissue dependent. During the exposure to heat stress, the heart, liver and kidney of broiler chickens exhibited increased amounts of Hsp70 protein and mRNA. The expression of hsp70 mRNA in the heart, liver and kidney of heat-stressed broilers increased significantly and attained the highest level after a 2-h exposure to elevated temperatures. However, significant elevations in Hsp70 protein occurred after 2, 5, and 3 h of heat stressing, respectively, indicating that the stress-induced responses vary among different tissues.