Concise Review: MSC Adhesion Cascade-Insights into Homing and Transendothelial Migration.

Mesenchymal stem cells (MSCs) are promising candidates for adult cell therapies in regenerative medicine. To fully exert their potential, efficient homing and migration toward lesion sites play an important role. Local transplantation deposits MSC in spatial proximity to the lesion, but often requires invasive procedures. Systemic administration routes are favored, but require the targeted extravasation of the circulating MSC at the site of injury. Transplanted MSC can indeed leave the blood flow and transmigrate through the endothelial barrier, and reach the lesion site. However, the underlying processes are not completely dissolved yet. Recent in vitro and in vivo research identified some key molecules scattered light on the extravasation mechanism. This review provides a detailed overview over the current knowledge of MSC transendothelial migration. We use the leukocyte extravasation process as a role model to build a comprehensive concept of MSC egress mechanisms from the blood stream and identified relevant similarities as well as important differences between the extravasation mechanisms. Stem Cells 2017;35:1446-1460.

Changes in T2 relaxation time after stroke reflect clearing processes.

BACKGROUND AND PURPOSE: CT and MR imaging techniques are frequently used for the diagnosis and progress monitoring of ischemic stroke in clinical practice and research. After stroke, both methods are characterized by a transient pseudo-normalized imaging signal, the so-called fogging phenomenon. This study evaluates potential pathophysiological changes associated with fogging, as well as its influence on the correct determination of the ischemic lesion in a rat stroke model. METHODS: Male spontaneously hypertensive rats were subjected to permanent middle cerebral artery occlusion. Ischemic lesion volume, brain edema and gray scale value spread within the ischemic lesion were determined on T2-weighted MR sequences at days 1, 4, 8, 11 and 29 after stroke onset, and compared with immunohistochemistry for astrogliosis, microglia/macrophage infiltration and angiogenesis. RESULTS: All animals showed MR fogging at days 4, 8 and 11 after stroke. The transient normalization of T2 signals occurred independently from the development of infarct volumes, but coincided well with the spatio-temporal occurrence of necrosis, angiogenesis and microglia/macrophage infiltration. CONCLUSIONS: Our results suggest that the fogging effect reflects the clearance of necrotic tissue within the ischemic lesion and is thus not relevant for the determination of the lesion volume.

Crucial role of interleukin-6 in the development of norepinephrine-induced left ventricular remodeling in mice.

BACKGROUND: Elevated serum concentration of interleukin (IL)-6 is a predictor for poor prognosis in congestive heart failure. It was shown previously in rats, that IL-6 expression in the left ventricle (LV) was followed by LV hypertrophy. METHODS: Using IL-6 deficient mice (IL-6(-/-)), we studied the role of IL-6 in a model of norepinephrine (NE)-induced LV hypertrophy. RESULTS: In wild type (WT) mice, IL-6 mRNA expression and its concentration in the serum were elevated after 4 h of NE-treatment (s.c. 0.25 mg.h)./kg Further, NE-induced LV hypertrophy was detected: LV weight/body weight (LVW/BW) ratio (+12.3+/-3%, p < 0.05) and mRNA expression of atrial natriuretic peptide (ANP) in WT mice (+120+/-25%, p < 0.05) after 3 days were increased. In contrast, NE did not induce elevation of LVW/BW ratio and ANP expression in IL-6(-/-) mice. Replacement with recombinant IL-6 restored the hypertrophy-inducing effect of NE in IL-6(-/-) mice. As to the extracellular matrix (ECM) proteins, NE increased collagen type I and III expression only in WT mice and not in IL-6(-/-) mice. The addition of recombinant IL-6 elevated the expression of the ECM proteins to the WT level. CONCLUSION: IL-6 is a major player in the development of NE-induced LV hypertrophy in mice.

Ribose treatment reduced the infarct size and improved heart function after myocardial infarction in rats.

OBJECTIVE: In this study the effect of ribose on heart function and infarct-size was analyzed 6 h after myocardial infarction (MI) in rats. METHODS: Continuous i.v.-infusion of NaCl or ribose (200 mg/kg/h) was started one day prior to induction of MI in female Sprague-Dawley rats which was done by ligation of the left coronary artery. Six hours after MI heart function was measured with 3F tip catheter, cardiac output by thermodilution method. Thereafter the ischemic area was delineated by Evans Blue infusion, and the infarct area was visualized by triphenyltetrazolium chloride staining. The mRNA expression of interleukin (IL)-1beta, IL-6, matrix-metalloproteinase (MMP)-8, and -9 was measured by ribonuclease protection assay. RESULTS: Heart function was severely depressed 6 hours after coronary artery occlusion, but recovered significantly under the influence of ribose. Left ventricular (LV) systolic pressure (LVSP) and contractility (LVdP/dtmax) were restored to the normal levels of sham-operated animals, while parameters of LV relaxation (LVdP/dtmin and time constant of relaxation tau) were impaired compared to sham-operated animals, but significantly improved by ribose treatment compared to sham-treated MI-rats. Moreover, the infarct size was significantly smaller in the ribose treated animals despite a comparable ischemic area at risk in all MI-rats. The cytokine mRNA expression after MI was significantly reduced after ribose treatment, while there were no differences regarding MMP expression. CONCLUSION: MI size was significantly reduced and LV function significantly improved by ribose treatment at 6 h after MI. This seemed to be based on slowing the velocity of the necrotic wave front across the LV wall after MI resulting in smaller infarcts.

Cord blood cell therapy alters LV remodeling and cytokine expression but does not improve heart function after myocardial infarction in rats.

OBJECTIVE: In this study the ability of unrestricted somatic stem cells (USSC) and mononuclear cord blood cells (MN-CBC) was tested to improve heart function and left ventricular (LV) remodeling after myocardial infarction (MI). METHODS: The cells were delivered by i.v. or intramyocardial injections in rat models of MI by permanent coronary artery occlusion and by ischemia/reperfusion (I/R) injury. Heart function and remodeling was followed by recurrent echocardiography over 8 or 12 weeks after which catheterization was performed. RESULTS: Although injected labeled cells could be observed within the myocardium for up to 6 d, there was no sign of cardiac regeneration 8 or 12 weeks after MI. However, the mRNA expression of components of the extracellular matrix was attenuated in the infarct scar 12 weeks after MI and cell injection. Additionally, the expression of interleukin (IL)-6 but not of IL-1 beta increased at the site of injury and the adjacent border-zone 12 weeks after I/R and USSC-injection. However, these effects did not translate into improved heart function or attenuated LV dilatation. CONCLUSION: These data indicate that cord blood cell implantation after MI acts through paracrine mechanisms to modify remodeling rather than myocyte regeneration. The role of myofibroblasts and the optimal conditions of cell application need to be determined to translate these mechanisms into functional improvement.

Contrast enhanced echocardiographic follow-up of cardiac remodeling and function after myocardial infarction in rats.

Echocardiography is a reliable and commonly used method to examine cardiac diseases. Recent employment of modern technologies provides new opportunities to study left ventricular (LV) remodeling after myocardial infarction (MI) also in small rodents. LV volumes as most important prognostic parameters can be estimated by noncontrast enhanced echocardiography in rats from M-mode or single cross sections only. In this study, contrast enhanced echocardiography and volume measurements by the biplane method of discs (Simpson's rule) were applied in rats to monitor remodeling and function after MI. MI was induced in female Sprague-Dawley rats (n = 26 for MI, and n = 16 for sham). LV remodeling and heart function were serially studied by contrast enhanced echocardiography for 12 to 16 wk. At the end of the observation periods hemodynamic data were additionally measured by left and right heart catheterization. LV end systolic volume (LVESV) measured by biplane method of discs correlated best with LV developed pressure as indicator for severely impaired heart function. Interestingly, LV end systolic area (LVESA) from native short axis view correlated well with LVESV (R(2) = 0.93) and was the second best predictor for depressed heart function. Moreover, left atrial size was a powerful indicator of severely impaired heart function whereas ejection fraction or fractional area change were primarily related to infarct size. In conclusion, contrast enhanced echocardiography in rats is feasible and an economical method to study time-dependent LV remodeling and deterioration of contractile function after MI.

Embryonic endothelial progenitor cells expressing a broad range of proangiogenic and remodeling factors enhance vascularization and tissue recovery in acute and chronic ischemia.

Clonal embryonic endothelial progenitor cells (eEPCs) isolated from embryonic day 7.5 mice home specifically to hypoxic areas in mouse tumor metastases but spare normal organs and do not form carcinomas. Based on these results, we assessed the potential of eEPCs to enhance vascularization and limit organ dysfunction after ischemia in syngenic and xenotypic organisms. The angiogenic potential of eEPCs was evaluated in chronic ischemic rabbit hindlimbs after regional application by retroinfusion. eEPC treatment improved limb perfusion, paralleled by an increase in capillary density and collateral blood vessel number. Systemic eEPC infusion into mice after ischemic cardiac insult increased postischemic heart output measured by a marked improvement in left ventricle developed pressure and both systolic and diastolic functions. In vitro, eEPCs strongly induced vascular outgrowths from aortic rings. To address the molecular basis of this intrinsic angiogenic potential, we investigated the eEPC transcriptome. Genome-wide Affymetrix GeneChip analysis revealed that the eEPCs express a wealth of secreted factors known to induce angiogenesis, tissue remodeling, and organogenesis that may contribute to the eEPC-mediated beneficial effects. Our findings show that eEPCs induce blood vessel growth and cardioprotection in severe ischemic conditions providing a readily available source to study the mechanisms of neovascularization and tissue recovery.

Heart function and molecular biological parameters are comparable in young adult and aged rats after chronic myocardial infarction.

OBJECTIVE: To test the hypothesis that IL-1beta and IL-6 play a pivotal role after myocardial infarction (MI) particularly in aged rats. METHODS: Chronic MI was induced in young adult (3.5 months) and aged (18 months) female Sprague-Dawley rats by ligation of the left coronary artery. Sham-operated animals of corresponding age served as controls. Heart function was measured by catheterization 4 weeks after MI. The expression of IL-1beta, IL-6, TGF-beta-isoforms, ANF, and components of the extracellular matrix (pro-collagen I and III, colligin, MMP-2 and TIMP2) was measured by ribonuclease protection assay. RESULTS: Aged control rats differed from young adult rats in that LV-developed pressure (LVDP) was higher (161 vs. 147 mmHg, p<0.05) in response to the elevated total peripheral resistance (0.71 vs. 0.47 mmHg ml min/kg, p<0.05). Contractility was reduced in aged controls as indicated by decreased LV dP/dt (8.106 vs. 10.606 mmHg/s, p<0.05). LV function was severely depressed in both MI groups (reduction in LVDP by about 35% and LV dP/dt by about 30%, increase in LVEDP to 24 mmHg) while RVP and RV dP/dt markedly increased by about 100%. This was not different between both MI groups. ANF expression as a marker of hypertrophy was induced in both MI groups, but less pronounced in the LV of aged rats. Also, the mRNA expression pattern was qualitatively comparable, but showed gradual differences. CONCLUSION: These results indicate that aged rats compensate well for hemodynamic overload induced by MI. Also, the mechanisms of myocardial post-MI remodeling are comparable in young adult and aged rats.

Hematopoietic stem cells do not repair the infarcted mouse heart.

OBJECTIVE: Recent reports suggest that hematopoietic stem cells (HSC) can transdifferentiate into cardiomyoctes and contribute to myocardial regeneration after injury. This concept has recently been challenged by studies in which bone-marrow (BM)-derived cells do not acquire a cardiac phenotype after direct injection into ischemic myocardium. METHODS: In this study, we analyzed the effect of increased circulating adult BM cells by stimulation with stem cell factor (SCF; 200 microg/kg/d for 7 days) and granulocyte-colony stimulating factor (G-CSF, 50 microg/kg/d for 7 days) or by peripheral delivery of isolated adult BM cells on morphological and hemodynamic parameters of mouse hearts 6 weeks after induction of chronic myocardial infarction (MI). All animals were splenectomized to prevent sequestration of BM cells 2 weeks prior to the induction of MI. Cytokine treatment was initiated either 3 days prior to or 6 h after MI. Isolated, either whole or by magnetic beads lineage-depleted BM cells were injected via a tail vein 6 h after MI. RESULTS: Left and right ventricular (LV and RV) function revealed no improvement in any treatment group when compared to untreated MI animals at baseline resting conditions as well as after stimulation with norepinephrine (NE; 1, 5, 10, 25, 50, and 100 ng bolus i.v. in 10 microl each) as measured by catherization with ultraminiature 1.4 F tip pressure transducers 6 weeks after MI. Moreover, there was no sign of myocardial regeneration in histological or gene expression analyses. CONCLUSION: Mobilization or i.v. injection of BM cells do not have a measurable effect on cardiac regeneration.

Cardiac cytokine expression is upregulated in the acute phase after myocardial infarction. Experimental studies in rats.

OBJECTIVE: The proinflammatory cytokines interleukin (IL)-1beta and IL-6 are supposed to be involved in various cardiovascular diseases including reperfusion injury and cardiac hypertrophy. METHODS AND RESULTS: In the present study, we have examined the cytokine expression from 3 h up to 12 weeks after permanent coronary artery occlusion in rats. In the first 3-12 h, there was a strong induction in IL-1beta and IL-6 mRNA expression in the infarct area (up to 50-fold) as well as in the non-infarcted myocardium (up to 15-fold). From day 3 onwards the cytokine expression was not significantly altered compared to sham-operated controls. In addition, the expression of C/AATT-enhancer binding protein-beta was about fourfold elevated in the first hours after myocardial infarction, but not thereafter. Furthermore, the expression of gp130 and IL-6 receptor increased significantly in the infarct area. The elevation in cytokine expression preceded the increase in matrix-metalloproteinase-9 in the infarct area as well as the increase in ANP and collagen expression in the non-infarcted myocardium. CONCLUSIONS: We suggest that IL-6 and IL-1beta act synergistically in promoting resorption of the necrotic tissue, matrix remodeling and wound healing. Furthermore, they may be involved in the early induction of fibrosis and compensatory cardiac hypertrophy of the non-infarcted myocardium, but seem not to play a key role in long-term cardiac remodeling in chronic heart failure after myocardial infarction.

Significance of matrix metalloproteinases in norepinephrine-induced remodelling of rat hearts.

OBJECTIVE: Norepinephrine (NE) induced hypertrophy and remodelling of the extracellular matrix (ECM) in the left ventricle (LV) of the rat heart with resulting fibrosis. However, there was no increased collagen deposition in the right ventricle (RV). To test the hypothesis that lack of RV fibrosis is the result of elevated cleavage of collagens we inhibited the activity of matrix metalloproteinases (MMP) by doxycycline (Doxy) and then measured function and collagen metabolism in the RV as compared to the LV. METHODS: Female Sprague-Dawley rats were treated with 30 mg/kg per day doxycycline alone or in combination with i.v. infusion of NE (0.1 mg/kg per h). The activity of MMP-2 was increased both in the LV and RV after 3 days of NE infusion and reduced after concomitant doxycycline treatment which also caused inhibition when given alone. RESULTS: After 14 days of NE infusion in combination with doxycycline there was an additional increase in the NE-induced elevation of collagen accumulation in the LV (interstitial collagen fraction: NE-Doxy 1.797%, P<0.05 versus control and NE; NE 1.113%, P<0.05 versus control) and significant fibrosis in the RV (2.105%, P<0.05 versus control). This correlated with the prevention of the NE-induced elevation of RV systolic pressure (NE: 71.3 mmHg, P<0.05; NE-Doxy: 36.4 mmHg) and RV dP/dt(max) (NE: 5500 mmHg/s, P<0.05; NE-Doxy: 2550 mmHg/s). Also in the NE-stimulated LV, the doxycycline-induced collagen accumulation was associated with reduced LV dP/dt(max) (NE-Doxy: 13169 mmHg/s; NE: 18849 mmHg/s, P<0.05). CONCLUSION: MMP inhibition leads to myocardial stiffness with negative functional consequences for the RV and LV in NE-treated rat hearts.

Norepinephrine-induced acute heart failure in transgenic mice overexpressing erythropoietin.

OBJECTIVE: Overexpression of erythropoietin (Epo) in mice (Epo-tg6) leads to an increase in hematocrit and blood volume, and strongly reduces endurance upon exercise. It was the aim of this study to characterize the mechanisms underlying the reduced cardiac performance. METHODS: Left (LV) and right (RV) ventricular function was measured with and without norepinephrine (NE) stimulation in 12 anaesthetized Epo-tg6 and in 13 wild-type (WT) control mice. RESULTS: There were no differences in heart function under baseline resting conditions. Stimulation with NE (10 microl bolus injections of 1-100 ng per mouse) in WT mice led to a dose-dependent increase in heart rate (HR), LV developed pressure (LVDP) and rate of rise in LV pressure (LV dP/dt(max)), while LV end-diastolic pressure (LVEDP) was unchanged. Except for HR, these parameters increased to a lesser extent in EPO-tg6 mice. Strikingly, LVEDP strongly increased in Epo-tg6 mice after NE (up to >20 mmHg). Eleven out of 13 Epo-tg6, but none of the WT mice died or required resuscitation after high-doses of NE. In these cases severe diastolic dysfunction became overt since the relative myocardial relaxation time was significantly prolonged and the duration of diastole was shortened. Moreover, the ECG showed a marked ST segment depression as well as deep negative T-waves. The NE-induced reduction in myocardial adenosin-triphosphate (ATP) content was more pronounced in Epo-tg6 mice after 10 min of continuous NE infusion (50 ng/min per mouse). CONCLUSION: NE-induced stress in Epo-tg6 mice led to acute heart failure associated with diastolic dysfunction and myocardial ischemia.

Specific Mechanisms Underlying Right Heart Failure: The Missing Upregulation of Superoxide Dismutase-2 and Its Decisive Role in Antioxidative Defense.

AIMS: Research into right ventricular (RV) physiology and identification of pathomechanisms underlying RV failure have been neglected for many years, because function of the RV is often considered less important for overall hemodynamics and maintenance of blood circulation. In view of this, this study focuses on identifying specific adaptive mechanisms of the RV and left ventricle (LV) during a state of chronic nitric oxide (NO) deficiency, one of the main causes of cardiac failure. NO deficiency was induced in rats by L-NAME feeding over a 4 week period. The cardiac remodeling was then characterized separately for the RV/LV using quantitative real-time polymerase chain reaction, histology, and functional measurements. RESULTS: Only the RV underwent remodeling that corresponded morphologically and functionally with the pattern of dilated cardiomyopathy. Symptoms in the LV were subtle and consisted primarily of moderate hypertrophy. A massive increase in reactive oxygen species (ROS) (+4.5±0.8-fold, vs. control) and a higher degree of oxidized tropomyosin (+46%±4% vs. control) and peroxynitrite (+32%±2% vs. control) could be identified as the cause of both RV fibrosis and contractile dysfunction. The expression of superoxide dismutase-2 was specifically increased in the LV by 51%±3% and prevented the ROS increase and the corresponding structural and functional remodeling. INNOVATION: This study identified the inability of the RV to increase its antioxidant capacity as an important risk factor for developing RV failure. CONCLUSION: Unlike the LV, the RV did not display the necessary adaptive mechanisms to cope with increased oxidative stress during a state of chronic NO deficiency.

Astrocytic mitochondrial membrane hyperpolarization following extended oxygen and glucose deprivation.

Astrocytes can tolerate longer periods of oxygen and glucose deprivation (OGD) as compared to neurons. The reasons for this reduced vulnerability are not well understood. Particularly, changes in mitochondrial membrane potential (Δψ(m)) in astrocytes, an indicator of the cellular redox state, have not been investigated during reperfusion after extended OGD exposure. Here, we subjected primary mouse astrocytes to glucose deprivation (GD), OGD and combinations of both conditions varying in duration and sequence. Changes in Δψ(m), visualized by change in the fluorescence of JC-1, were investigated within one hour after reconstitution of oxygen and glucose supply, intended to model in vivo reperfusion. In all experiments, astrocytes showed resilience to extended periods of OGD, which had little effect on Δψ(m) during reperfusion, whereas GD caused a robust Δψ(m) negativation. In case no Δψ(m) negativation was observed after OGD, subsequent chemical oxygen deprivation (OD) induced by sodium azide caused depolarization, which, however, was significantly delayed as compared to normoxic group. When GD preceded OD for 12 h, Δψ(m) hyperpolarization was induced by both GD and subsequent OD, but significant interaction between these conditions was not detected. However, when GD was extended to 48 h preceding OGD, hyperpolarization enhanced during reperfusion. This implicates synergistic effects of both conditions in that sequence. These findings provide novel information regarding the role of the two main substrates of electron transport chain (glucose and oxygen) and their hyperpolarizing effect on Δψ(m) during substrate deprivation, thus shedding new light on mechanisms of astrocyte resilience to prolonged ischemic injury.

Continuous adenosine A2A receptor antagonism after focal cerebral ischemia in spontaneously hypertensive rats.

Antagonism of the adenosine A2A receptor (A2AR) has been shown to elicit substantial neuroprotective properties when given immediately after cerebral ischemia. We asked whether the continuous application of a selective A2AR antagonist within a clinically relevant time window will be a feasible and effective approach to treat focal cerebral ischemia. To answer this question, we subjected 20 male spontaneously hypertensive rats to permanent middle cerebral artery occlusion and randomized them equally to a verum and a control group. Two hours after stroke onset, the animals received a subcutaneous implantation of an osmotic minipump filled with 5 mg kg(-1) day(-1) 8-(3-chlorostyryl) caffeine (CSC) or vehicle solution. The serum level of CSC was measured twice a day for three consecutive days. The infarct volume was determined at days 1 and 3 using magnetic resonance imaging. We found the serum level of CSC showing a bell-shaped curve with its maximum at 36 h. The infarct volume was not affected by continuous CSC treatment. These results suggest that delayed and continuous CSC application was not sufficient to treat acute ischemic stroke, potentially due to unfavorable hepatic elimination and metabolization of the pharmaceutical.

Object-based analysis of astroglial reaction and astrocyte subtype morphology after ischemic brain injury.

The astrocytic response to ischemic brain injury is characterized by specific alterations of glial cell morphology and function. Various studies described both beneficial and detrimental aspects of activated astrocytes, suggesting the existence of different subtypes. We investigated this issue using a novel object-based approach to study characteristics of astrogliosis after stroke. Spontaneously hypertensive rats received permanent middle cerebral artery occlusion. After 96 h, brain specimens were removed, fixed and stained for GFAP, glutamine synthetase (GS), S100Beta and Musashi1 (Msh1). Three regions of interest were defined (contralateral hemisphere, ipsilateral remote zone and infarct border zone), and confocal stacks were acquired (n=5 biological with each n=4 technical replicates). The stacks were background-corrected and colocalization between the selected markers and GFAP was determined using an automated thresholding algorithm. The fluorescence and colocalization channels were then converted into 3D-objects using both intensity and volume as filters to ultimately determine the final volumes of marker expression and colocalization, as well as the morphological changes of astrocyte process arborisation. We found that both S100Beta and Msh1 determined the same GFAP-positive astroglial cell population albeit the cellular compartments differed. GFAP stained most of the astrocyte processes and is hence suitable for the analysis of qualitative characteristics of astrogliosis. Due to its peri-nuclear localization, Msh1 is appropriate to estimate the total number of astrocytes even in regions with severe reactive astrogliosis. GS expression in GFAP-positive astrocytes was high in the remote zone and low at the infarct border, indicating the existence of astrocyte subclasses.

Intravenous human umbilical cord blood transplantation for stroke: impact on infarct volume and caspase-3-dependent cell death in spontaneously hypertensive rats.

Transplantation of human umbilical cord blood cells (HUCBC) produces reliable behavioral and morphological improvements in animal models of stroke. However, the mechanisms of action still have not been fully elucidated. The aim of the present study is the evaluation of potential neuroprotective effects produced by HUCBC in terms of reduced infarct volume and caspase-3-dependent cell death. Permanent middle cerebral artery occlusion was induced in 90 spontaneously hypertensive rats. The animals were randomly assigned to the control group (n=49) or the verum group (n=41). The cell suspension (8 × 10(6) HUCBC per kilogram bodyweight) or vehicle solution was intravenously administered 24h after stroke onset. Fifty subjects (n=25/25) were sacrificed after 25, 48, 72 and 96h, and brain specimens were removed for immunohistochemistry for MAP2, cleaved caspase-3 (casp3) and GFAP. Another 42 animals (n=26/16) were sacrificed after 0, 6, 24, 36 and 48h and their brains processed for quantitative PCR for casp3 and survivin. The infarct volume remained stable over the entire experimental period. However, cleaved casp3 activity increased significantly in the infarct border zone within the same time frame. Numerous cleaved casp3-positive cells were colocalized with the astrocytic marker GFAP, whereas cleavage of neuronal casp3 was observed rarely. Neither the infarct volume nor casp3 activity was significantly affected by cell transplantation. Delayed systemic transplantation of HUCBC failed to produce neuroprotective effects in a permanent stroke model using premorbid subjects.

Tissue inhibitor of matrix metalloproteinase-1 in norepinephrine-induced remodeling of the mouse heart.

BACKGROUND: Matrix metalloproteinases (MMPs) play an important role in myocardial remodeling. Their activity is regulated by the tissue inhibitors of metalloproteinases (TIMPs). The present study analyzed the contribution of changes in functional and molecular parameters to early cardiac remodeling in mice hearts. The role that TIMPs might play in this process was specially acknowledged. METHODS: The remodeling was induced by norepinephrine (NE) given sc in balb/c mice. Varying concentrations, time and the addition of a neutralizing TIMP-1 antibody were evaluated. RESULTS: High dose NE led to insufficiency of the left ventricle (LV) as evidenced by reduced NE-induced elevation of LV systolic pressure, contractility and relaxation. Further, signs of lung congestion were seen. NE induced a concentration-dependent increase of LV weight/body weight (LVW/BW) ratio and elevated mRNA expression of atrial natriuretic peptide (ANP). This was accompanied by induction of collagen type I and III, as well as TIMP-1 expression. CONCLUSIONS: The NE-induced increase of TIMP-1 expression may induce the elevation of the antihypertrophic cardiac factor ANP since NE-induced increase of ANP expression was abolished by neutralizing TIMP-1 antibody. Thus, TIMP-1 may mediate ANP-induced attenuation of NE-induced hypertrophy in the mouse heart.

Heart function and cytokine expression is similar in mice and rats after myocardial infarction but differences occur in TNFalpha expression.

Large myocardial infarction (MI) causes substantial cardiac remodeling and often leads to heart failure. The genetically engineered mouse is believed to provide a powerful tool for investigating the underlying pathophysiological mechanisms and for developing new therapeutic strategies. The present study investigates the functional parameters and expression levels of transforming growth factor (TGF) beta isoforms, interleukin-6 (IL-6) and tumor necrosis factor (TNF) alpha, which may be involved in the remodeling mechanisms, in a mouse model of MI; comparisons with data from rats were also made. Female Sprague-Dawley rats ( n=10-12 at each time point) and female Balb/c mice ( n=6-8 at each time point) were used. In both mice and rats MI induced a time-dependent reduction in heart function with subsequent development of heart failure. The hemodynamic consequences after 4 weeks are characterized by reduced left ventricular (LV) developed pressure and increased right ventricular (RV) developed pressure. The pattern of increased expression of most, but not all, of the analyzed cytokines and growth factors is comparable. This emphasizes the important role of these factors in the remodeling processes. However, TNFalpha was more strongly expressed in both the infarct and the non-infarcted area of mice. Since functional and molecular biological parameters can readily be measured in mice with advanced technologies, this qualifies this species as a powerful experimental model, particularly in view of the various transgenic and knock-out mice that are available.