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PubMed1992

The effect of age on lipid composition and order of rat cerebral microvessels.

To determine if alterations in lipid composition and/or membrane order of cerebral microvessels may contribute to the age-related changes in blood-brain barrier (BBB) function, cerebral microvessels isolated from male Fischer 344 rats at 3 (young), 12 (intermediate age), and 24 (aged) months of age were studied. The steady state fluorescence polarization of diphenylhexatriene incorporated into isolated cerebral microvessel membranes at 35 degrees C, in aged rats was not different compared to young rats (0.2787 +/- 0.0029 vs 0.2847 +/- 0.0049). In addition, the thermotropic transition temperature of these membranes was not altered with age. Moreover, the fatty acid composition, the double bond index as well as cholesterol to phospholipid molar ratios were not significantly altered with age. In contrast, the concentration of conjugated dienes in lipid extracts of cerebral microvessels of aged rats (10.04 +/- 1.10 O.D./mg phospholipids) was significantly increased compared to the concentration in young rats (6.98 +/- 0.52 O.D./mg phospholipids) (p less than 0.01). It is concluded that aging is not associated with significant changes in lipid composition or membrane order of cerebral microvessels. However, the increased concentration of conjugated dienes in cerebral microvessels of aged rats is indicative on ongoing free radical damage in these microvessels which may contribute to the age-related changes in BBB function.

Aging↗

PubMed1995

Growth, microvessel density and tumor cell invasion of human colon adenocarcinoma under repeated treatment with hyperthermia and serotonin.

The intratumoral microvessel density of malignant breast cancer has been shown to be an important prognostic marker. In this study, we tested whether repeated treatment with hyperthermia and serotonin (5-hydroxytryptamine) reduces tumor growth and alters tumor histology of a colon adenocarcinoma, and whether capillary density in this tumor can also be regarded as an important prognostic marker. Previously we have shown that acute treatment of colon adenocarcinoma with hyperthermia, alone or in combination with serotonin, selectively constricted tumor microvessels, which could reduce blood flow and inhibit tumor growth. Fourteen days after human colon adenocarcinoma had been transplanted under the dorsal epidermis of the ear of athymic nude mice, the surgically unprepared tumor-bearing ear of the sodium-pentobarbital-anesthetized animal was treated with hyperthermia alone (group 1, 43 degrees C for 45 min), or with hyperthermia plus topically applied serotonin (1 mM/l, 43 degrees C for 45 min, group 2) twice per week for 5 weeks. Control animals were not treated (group 3). Histological slides (stained with hematoxylin/eosin) were prepared 42 days after implantation, for analysis of tumor grading, tumor cell invasion into the surrounding tissue and microvessels, and the number of intratumoral microvessels. Repeated hyperthermia inhibited tumor growth, reduced the number of intratumoral microvessels, did not change tumor cell invasion and increased the necrotic area. Hyperthermia and serotonin did not influence tumor growth, but strongly reduced cell invasion and the number of microvessels. The area of necrosis was very large. Thus, analysis of microvessel density in colon adenocarcinoma seems not to be an important tool for predicting therapeutic efficacy.

Adenocarcinoma↗

PubMed1995

cAMP-dependent protein kinase in cerebral microvessels in aging and Alzheimer disease.

The purpose of this study was to compare the effects of aging and Alzheimer disease (AD) on the important intracellular signaling enzyme cAMP-dependent protein kinase A (PKA) in cerebral microvessels. PKA activity and levels were measured in microvessels isolated from the brains of adult and aged rodents as well as from the cerebral cortices of AD and elderly control patients. The results showed that cerebral microvessels from aged rats have significantly (p < 0.01) higher PKA activity and levels when compared to cerebral microvessels from adult rats. In contrast, no significant difference was found between PKA activity or levels in cerebral microvessels from AD patients when compared to controls. These results indicate that in cerebral microvessels both PKA activity and levels increase with age but are unaffected by AD. The data suggest that protein phosphorylation in brain microvessels may be affected differentially by aging and dementia.

Aged↗

PubMed1998

Evaluation of microvessel density by computerised image analysis in human renal cell carcinoma. Correlation to pT category, nuclear grade, proliferative activity and occurrence of metastasis.

A high microvessel density is suspected to favour tumour progression and the occurrence of metastasis. To elucidate the significance of abundant vessels for the behaviour of human renal carcinomas, the microvessel density of 110 renal cell carcinomas was correlated to pT category, nuclear grade, proliferative activity, occurrence of metastasis and relapse-free survival interval. The microvessels were quantified using CD31 immunostaining of endothelial cells and computer-aided image analysis. The rules for reproducible microvessel counting, as defined by Weidner, were strictly observed. A statistically significant relationship between the microvessel density and nuclear grade, proliferative activity, occurrence of metastasis and relapse-free survival was found; only for tumour size could no such relation be seen. Perplexingly, there is a diminution of microvessel density in association with increasing nuclear grade, proliferative activity, relapse-free survival interval and frequency of metastasis. This finding is contradictory to the hypothesis that an increasing microvessel density indicates a worsening prognosis.

Antibodies↗

PubMed2007

Lymphatic microvessel density is an independent prognostic factor in colorectal cancer.

PURPOSE: Although lymph node metastasis via lymphatic vessels often is related with an adverse outcome, it is not well known whether lymphatic spread to lymph node needs the development of the new lymphatic formation. In addition, the correlation between lymphangiogenesis and prognosis has not been well documented. This study was designed to assess the prognostic value of lymphangiogenesis and lymphatic vessel invasion in colorectal cancer. METHODS: We examined 106 colorectal cancer specimens by immunostaining for podoplanin, lymphatic endothelial specific marker. We evaluated lymphangiogenesis, as measured by lymphatic microvessel density, and lymphatic vessel invasion. We next investigated the association of these two parameters with the clinicopathologic findings and prognosis. RESULTS: A significant correlation was observed between high lymphatic microvessel density and positive lymphatic vessel invasion (P = 0.0003). Positive lymphatic vessel invasion was significantly associated with the presence of lymph node metastasis (P = 0.0071). The survival curves demonstrated that both high lymphatic microvessel density and positive lymphatic vessel invasion were correlated with an adverse outcome (P = 0.0004 and P = 0.009, respectively). In a univariate analysis, high lymphatic microvessel density and positive lymphatic vessel invasion were negatively associated with the overall survival (P = 0.0011 and P = 0.0118, respectively). Furthermore, high lymphatic microvessel density, but not lymphatic vessel invasion, correlated with a poor outcome in a multivariate analysis (P = 0.0114). CONCLUSIONS: Our data suggested that lymphatic vessel invasion was related with lymph node metastasis and that both lymphatic microvessel density and lymphatic vessel invasion were related with an adverse outcome in colorectal cancer. Furthermore, lymphatic microvessel density may be a useful prognostic factor in colorectal cancer.

Adult↗

PubMed1992

Serial reconstruction of beta-protein amyloid plaques: relationship to microvessels and size distribution.

The suggestion that the amyloid plaques in Alzheimer disease are formed by abnormal leakage from microvessels is mainly based on the finding that many plaques are topographically associated with microvessels. However, because the microvessel network is dense and amyloid plaques are numerous, the frequently observed association may result from chance contact, especially for larger plaques. Therefore, we determined the frequency of this association as a variable of plaque size. If all the amyloid plaques are associated with microvessels, a constant and high rate of association would be expected for all plaque sizes. On the other hand, if the association is a chance contact, larger plaques would show more frequent contact than smaller ones. Sections were double-immunostained for amyloid plaques and microvessels with antibodies raised against beta-protein and collagen type IV, respectively. Amyloid plaques were reconstructed using 12 serial sections (7 microns thick) from the entorhinal cortex of two Alzheimer patients. With reconstruction we determined the size distribution of amyloid plaques as well as the influence of size on vascular association. All the amyloid plaques larger than 42 microns were associated with microvessels, however, the smaller the amyloid plaques, the less frequently they were associated with microvessels. Interestingly, although diffuse amyloid plaques occur in all size classes, core-containing amyloid plaques have a more discrete size. We conclude that the topographical relationship between amyloid deposition and capillaries does not support the leakage theory for amyloid plaque formation.

Aged↗

PubMed1990

Acute endothelial swelling is induced in endoneurial microvessels by ischemia.

Structural alterations of endoneurial microvessels occur in diabetic neuropathy and are statistically associated with severity of nerve fiber loss and teased fiber abnormality. It is therefore hypothesized that the microvessel alterations may cause or contribute to pathologic alterations of nerve fibers in diabetic neuropathy, possibly through hypoxic injury. The mechanism of the microvessel change in diabetic neuropathy is unknown. The role of microvessels and details of microvessel structure in other possible ischemic neuropathies has not been studied completely. Already there is evidence that hypoxia induces endothelial swelling but this has not been characterized or quantitated in nerve. To determine the acute morphologic effect of ischemia on ultrastructural features of transverse profiles of endoneurial microvessels major pelvic arteries were ligated in rats. At 36 h mean lumen and mural areas were greater in ischemic than in control nerves. All components (endothelium, pericytes and basement membrane) were on average greater in ischemic than controls. The greatest increase was in endothelial cells. In these cells swollen mitochondria were abundant. This study demonstrates that acute ischemia induces swelling of the cells and organelles of endoneurial microvessels.

Animals↗

PubMed2001

Dynamic platelet accumulation at the site of the occluded middle cerebral artery and in downstream microvessels is associated with loss of microvascular integrity after embolic middle cerebral artery occlusion.

Information is lacking regarding dynamic platelet accumulation at the site of the occluded middle cerebral artery (MCA) and the relationship between platelet aggregation in downstream cerebral microvessels and loss of perfusion and vascular integrity of these microvessels. In the present study, we employed a model of embolic MCA occlusion in the rat to simultaneously measure temporal and spatial profiles of platelet accumulation at the site of the embolus occluding the MCA and within downstream cerebral microvessels. We also measured the integrity of microvessels and matrix metalloproteinase (MMP) activity in ischemic brain. Rats (n=36) were subjected to embolic MCA occlusion. Immunohistochemistry was used to detect microvascular integrity, plasminogen activator inhibitor 1 (PAI-1) and the deposition of fibrin. SDS-PAGE zymography was used to measure MMP2 and MMP9 activities. Accumulation of platelets and increases in PAI-1 immunoreactivity at the site of the embolus occluding the MCA were detected 1 h (n=7) and 4 h (n=7) after ischemia, respectively, and numbers of GPIIb/IIIa immunoreactive downstream cerebral microvessels increased significantly (209+/-59; n=7; P<0.05) 4 h after ischemia, suggesting dynamic platelet aggregation. A significant (n=7; P<0.01) diffuse loss of type IV collagen immunoreactivity in microvessels was temporally associated with platelet GPIIb/IIIa immunoreactivity within the vessels. Triple immunostaining revealed that microvessels containing platelet aggregates exhibited loss of type IV collagen immunoreactivity and both intra- and extra-vascular fibrin deposition, suggesting that intravascular platelet aggregation is associated with decreases in the integrity of the microvascular basal lamina and blood-brain barrier leakage. A significant increase (P<0.05) in MMP9 was detected at 4 h (n=3) and 24 h (n=3) after ischemia but levels of MMP2 were not significantly changed in ischemic brain. Our data suggest that dynamic platelet aggregation in ischemic brain may contribute to time-dependent resistance to fibrinolysis. In addition, platelet deposition and increased MMP9 coincided with degradation of type IV collagen and loss of vascular integrity. These data suggest an important role for post-occlusive distal platelet deposition in the pathophysiology of stroke.

Animals↗

PubMed2003

Increased expression of cardiac angiotensin II type 1 (AT(1)) receptors decreases myocardial microvessel density after experimental myocardial infarction.

OBJECTIVE: To study the effects of increased levels of myocardial angiotensin II type 1 (AT(1)) receptor on microvascular growth following myocardial infarction (MI). METHODS: MI was created in transgenic rats (TGR) with a cardioselective overexpression of the AT(1) receptor. We used Sprague-Dawley (SD) rats as controls. Some of the rats were treated with the selective AT(1) receptor blocker losartan (Los). Rats were sacrificed after 3 weeks. RESULTS: MI caused left ventricular (LV) hypertrophy and LV dysfunction in both SD and TGR, which was prevented by AT(1) receptor blockade. Furthermore, MI decreased microvessel density in the non-infarcted myocardium (SD MI: 1653+/-37/mm(2), P<0.01 vs. sham-operated controls), however, microvessel density decreased significantly more in TGR with MI (1298+/-33/mm(2), P<0.01 vs. SD MI). AT(1) receptor blockade restored microvessel density (SD MI Los: 2046+/-195/mm(2); TGR MI Los: 1742+/-47/mm(2); P<0.01 vs. untreated). The differences in microvessel density were still present after correction for LV hypertrophy. The increase in microvessel density after AT(1) receptor blockade was not accompanied by increased myocardial vascular endothelial growth factor (VEGF) levels. Microvessel density correlated with parameters of myocardial stretch, such as LV end-diastolic pressure (-0.681, P<0.001) and N-ANP (-0.424, P=0.01). CONCLUSIONS: Microvessel density after MI is decreased when the AT(1) receptor is overexpressed, and this is amenable to AT(1) receptor blockade. This suggests that efficacy of AT(1) receptor blockers post-MI may not only be due to attenuation of LV remodeling, but also to a stimulatory effect on angiogenesis.

Angiotensin Receptor Antagonists↗

PubMed2000

Angiogenesis of endometrial carcinomas assessed by measurement of intratumoral blood flow, microvessel density, and vascular endothelial growth factor levels.

OBJECTIVE: To evaluate the relationship between blood flow in the tumor assessed by color Doppler ultrasound, microvessel density, and vascular endothelial growth factor levels in endometrial carcinoma. METHODS: Forty-nine patients undergoing surgery for endometrial carcinoma were enrolled. Transvaginal color Doppler ultrasound was performed preoperatively and the lowest resistance index (RI) in the tumor was recorded for analysis. Vascular endothelial growth factor in the tumor was quantified by enzyme immunoassay. The microvessel density of the excised tumor was assessed immunohistochemically. The relationships between the corresponding RI, microvessel density, and vascular endothelial growth factor level of the tumor tissues and clinical and pathologic parameters were analyzed. RESULTS: Significantly lower RIs were noted in tumors of stage II or greater (0.37 compared with 0.50, P <.001), of high histologic grade (grade 3) (0.34 compared with 0.49, P =.004), with deep myometrial invasion (one-half depth or greater) (0.39 compared with 0.49, P =.002), with lymphovascular emboli (0.38 compared with 0.49, P <.001), or with lymph node metastasis (0.30 compared with 0.49, P <.001) compared with stage I tumors and tumors of histologic grade 1 or 2, with superficial myometrial invasion, without lymphovascular emboli, or with no lymph node metastasis. Increased vascular endothelial growth factor levels and microvessel density (x200 field) also were detected in tumors of stage II or greater (975 compared with 129 pg/mg, P =.014; and 88 compared with 61, P =.018, respectively), with lymphovascular emboli (1138 compared with 120 pg/mg, P =.002; and 86 compared with 63, P =.023), or with lymph node metastasis (1011 compared with 95 pg/mg, P <.001; and 98 compared with 61, P =. 019). Resistance index, microvessel density, and vascular endothelial growth factor levels in the tumor showed linear correlations (RI compared with microvessel density: r = -.32, P =. 03; RI compared with vascular endothelial growth factor levels: r = -.40, P =.004; microvessel density compared with vascular endothelial growth factor levels: r =.36, P =.011). CONCLUSION: Blood flow assessed by color Doppler ultrasound has histologic and biologic correlations with angiogenesis and vascular endothelial growth factor levels and might play an important role in predicting tumor progression and metastasis in endometrial carcinoma.

Adult↗

PubMed2002

VEGF mRNA expressed in microvessels of neonatal and adult rat cerebral cortex.

We measured mRNA levels of vascular endothelial growth factor (VEGF) and its Flk-1/KDR receptor in isolated cerebral cortical microvessels and in the cerebral cortex of neonatal (1 week) and adult (11 week) rats using reverse transcription-polymerase chain reaction (RT-PCR). Cerebral microvessels were isolated by density centrifugation, mesh filtration and passage through glass bead columns. The dominant cell types in this preparation are endothelial cells and pericytes. Among the four isoforms of VEGF mRNA expressed in these tissues, VEGF(165) was dominant (67% higher than VEGF(189) or VEGF(206)). All isoforms of VEGF were higher in adult cortical microvessels than in cortical homogenates. In isolated microvessels, VEGF mRNA for all isoforms combined was 70% higher in the neonate than in the adult. VEGF receptor Flk-1/KDR mRNA was also present in cortical microvessels and was higher in neonatal than in adult microvessels. The results suggest that VEGF is normally expressed in cerebral microvessels of both neonates and adults. Whether the source of VEGF is the endothelial cell or pericyte, will determine if VEGF has autocrine or paracrine actions. The results also support the hypothesis that microvascular cell turnover continues in the adult brain.

Aging↗

PubMed2002

Expression of caveolin-1 in human brain microvessels.

Caveolae are microinvaginations of the cell plasma membrane involved in cell transport and metabolism as well as in signal transduction; these functions depend on the presence of integral proteins named caveolins in the caveolar frame. In the brain, various caveolin subtypes have been detected in vivo by immunocytochemistry: caveolin-1 and -2 were found in rat brain microvessels, caveolin-3 was revealed in astrocytes. The aim of this study was to identify the site(s) of cellular expression of caveolin-1 in the microvessels of the human cerebral cortex by immunofluorescence confocal microscopy and immunogold electron microscopy. Since in the barrier-provided brain microvessels tight relations occur between the endothelium-pericyte layer and the surrounding vascular astrocytes, double immunostaining with caveolin-1 and the astroglia marker, glial fibrillary acidic protein, was also carried out. Immunocytochemistry by confocal microscopy revealed that caveolin-1 is expressed by endothelial cells and pericytes in all the cortex microvessels; caveolin-1 is also expressed by cells located in the neuropil around the microvessels and identified as astrocytes. Study of the cortex microvessels carried out by immunoelectron microscopy confirmed that in the vascular wall caveolin-1 is expressed by endothelial cells, pericytes, and vascular astrocytes, and revealed the association of caveolin-1 with the cell caveolar compartment. The demonstration of caveolin-1 in the cells of the brain microvessels suggests that caveolin-1 may be involved in blood-brain barrier functioning, and also supports co-ordinated activities between these cells.

Blood-Brain Barrier↗

PubMed1995

Prognostic value of microvessel quantitation in cisplatin treated FIGO 3 and 4 ovarian cancer patients.

Primary ovarian carcinomas of 49 patients have been used to study the relation between microvessel counts and prognosis. All tumours were of the common epithelial type, FIGO 3 or 4, were treated by debulking surgery and cisplatin based chemotherapy. Primary tumour tissue obtained at surgery was embedded in paraffin, cut at 4 microns and stained with Ulex to accentuate the microvessels. The number of microvessels per unit area was counted according to a standardized protocol at a magnification of x 250 in 4 fields, which showed high field (R = 0.98) and acceptable case reproducibility (R = 0.70). Microvessell counts did not show associations with other prognostic variables such as FIGO stage, bulky disease-or-not, differentiation grade, DNA ploidy, volume percentage epithelium, mitotic activity index and mean nuclear area. In survival analysis, a tendency for worse prognosis with higher microvessel counts was found, although statistical significance was not reached (p = 0.25). Correction for volume percentage epithelium did not improve this result. Multivariate survival analysis did not reveal additional prognostic value of microvessel counts to other prognostic factors such as FIGO stage, bulky disease-or-not, volume percentage epithelium, mitotic activity index and mean and SD of nuclear area. In conclusion, although a tendency for worse survival with higher microvessel counts has been found, vascularity does not seem to have a significant impact on survival of adequately debulked advanced ovarian cancer patients treated with cisplatin.

Adult↗

PubMedDate not supplied

Lymph node reactivity and microvessel density in neck metastases of unknown primary squamous cell carcinoma.

BACKGROUND: Neoangiogenesis and the immune response are important mechanisms in metastasis development. AIM: to evaluate lymph node reactivity and microvessel density in neck metastasis of occult primary squamous cell carcinoma considering their histological and clinical variables. STUDY DESIGN: retrospesctive case-series. METHOD: 19 patients with neck metastasis of occult primary squamous cell carcinoma who underwent neck dissection between 1983 and 2000 were selected. The lymph nodes were reevaluated on the type of reactivity in both the cortical and paracortical areas, and the metastasis were assessed as to grade, desmoplasia, necrosis and microvessel density (CD34). The relationship between histological and clinical variables was evaluated. RESULTS: the median microvessel density was 91 vessels/mm2, varying from 28 to 145. Paracortical hyperplasia was more common in patients below 55 years of age (90%x44%, p=0.05), but there was no relationship between reactivity patterns and microvessel density with prognosis. The disease-free survival was 52% in 3 years, being similar in both groups, with higher or lower microvessel densities. CONCLUSION: microvessel density in neck metastasis of occult primary squamous cell carcinoma had a great individual variability. It wasnt possible to establish the relationship between microvessel density and the clinical or histological variables studied.

Carcinoma, Squamous Cell↗

PubMed1995

Nerve microvessel changes in diabetes are prevented by aldose reductase inhibition.

BACKGROUND: Despite the potential importance of endoneurial microvessel abnormalities in diabetic neuropathy, the pathogenesis of these abnormalities is incompletely understood. We wished to evaluate the effect of experimental diabetes on endoneurial microvessels and determine if an aldose reductase inhibitor alters any of the changes induced by diabetes. METHODS: We compared streptozocin diabetic rats with and without aldose reductase inhibitor treatment to non-diabetic rats after 10 months of diabetes. Transverse microvessels from the mid-sciatic level were studied by electron microscopic morphometric evaluation. RESULTS: Microvessel endothelial, pericyte, basement membrane and total mural area were greater in untreated diabetic animals than non-diabetic animals. Aldose reductase inhibitor treated diabetic animals had greater endothelial area and possibly pericyte area but not basement membrane or total mural area. CONCLUSIONS: This study demonstrates that endoneurial microvessel abnormalities can be detected in experimental diabetic neuropathy. Microvessel basement membrane thickening will be prevented by an aldose reductase inhibitor. One mechanism by which abnormal polyol pathway activity may contribute to diabetic neuropathy could be through damage to microvessels.

Aldehyde Reductase↗

PubMed1991

Bradykinin receptors of cerebral microvessels stimulate phosphoinositide turnover.

We examined by ligand binding methods whether bradykinin (BK) receptors exist in rat and pig cerebral microvessels, and in the cerebral cortex from which the microvessels were isolated. We found a high-affinity and saturable BK receptor site in both rat and pig cerebral microvessels, but not in their cerebral cortex. The maximal density of binding and the dissociation constant were 8.0 +/- 4.1 and 6.8 +/- 1.5 fmol/mg of protein and 47 +/- 24 and 150 +/- 8 pM (mean +/- SD) in cerebral microvessels of the pig and rat, respectively. The high-affinity specific binding of BK was effectively displaced by des-Arg0[Hyp3-Thi5-8,D-Phe7]BK, a specific B2 receptor antagonist, but not by des-Arg9[Leu8]BK, a specific B1 antagonist. We also demonstrated that BK increases phosphatidylinositol hydrolysis in cerebral microvessels of the rat and pig. This effect was also blocked by the B2, but not by the B1, antagonist. Increased phosphatidylinositol hydrolysis was manifested by a rapid transient increase in inositol trisphosphate and the later slow accumulation of inositol bisphosphate and inositol monophosphate. Preincubation of microvessels with phorbol ester, stable GTP analogs, pertussis toxin, or in Ca(2+)-free buffer did not influence BK activation of phosphatidylinositol hydrolysis. These results demonstrate the existence of BK receptors of the B2 subtype in brain microvessels, which may play an important role in modulation of the brain microcirculation, probably via increased phosphoinositide turnover.

Animals↗

PubMed2001

Engineering and characterization of functional human microvessels in immunodeficient mice.

SUMMARY: Current model systems used to investigate angiogenesis in vivo rely on the interpretation of results obtained with nonhuman endothelial cells. Recent advances in tissue engineering and molecular biology suggest the possibility of engineering human microvessels in vivo. Here we show that human dermal microvascular endothelial cells (HDMEC) transplanted into severe combined immunodeficient (SCID) mice on biodegradable polymer matrices differentiate into functional human microvessels that anastomose with the mouse vasculature. HDMEC were stably transduced with Flag epitope or alkaline phosphatase to confirm the human origin of the microvessels. Endothelial cells appeared dispersed throughout the sponge 1 day after transplantation, became organized into empty tubular structures by Day 5, and differentiated into functional microvessels within 7 to 10 days. Human microvessels in SCID mice expressed the physiological markers of angiogenesis: CD31, CD34, vascular cellular adhesion molecule 1 (VCAM-1), and intercellular adhesion molecule 1 (ICAM-1). Human endothelial cells became invested by perivascular smooth muscle alpha-actin-expressing mouse cells 21 days after implantation. This model was used previously to demonstrate that overexpression of the antiapoptotic protein Bcl-2 in HDMEC enhances neovascularization, and that apoptotic disruption of tumor microvessels is associated with apoptosis of surrounding tumor cells. The proposed SCID mouse model of human angiogenesis is ideally suited for the study of the physiology of microvessel development, pathologic neovascular responses such as tumor angiogenesis, and for the development and investigation of strategies designed to enhance the neovascularization of engineered human tissues and organs.

Absorbable Implants↗

PubMed2005

Focal cerebral ischemia preferentially affects neurons distant from their neighboring microvessels.

Developing cerebral infarction obscures the relationship of neurons to their local supply microvessels. We tested the notion that in the basal ganglia (i) an ordered relationship between neurons and their nearest neighboring microvessel exists, and (ii) focal ischemia predictably affects neuron integrity based on microvessel-neuron proximity. Distances between individual microvessels and their nearest neurons ([m-n distance]s) were measured in normal primates and ischemic subjects undergoing middle cerebral artery occlusion for 2 hours. An ordered microvessel-neuron relationship exists in the normal nonischemic basal ganglia within the early hours of focal ischemia. During ischemia normal (n) and sensitive (n*) neurons are interspersed. On average, neurons more distant from their nearest microvessel are most sensitive ([m-n distance]=16.2+/-11.2 microm versus [m-n* distance]=22.2+/-13.0 microm, 2P<0.00000001). Neurons not expressing glutamic acid decarboxylase were more likely to be sensitive than those with a normal microvessel-neuron relationship. In contrast, the [m-n distance] distribution of injured tyrosine hydroxylase-containing neurons was similar to those without tyrosine hydroxylase. Hence, the [m-n distance] relationship in the normal and ischemic basal ganglia is highly ordered, and distant neurons are consistently perturbed by ischemia, although this is not uniformly dependent on neurotransmitter type.

Animals↗