Diego Martínez-Caro

Treatment of reperfused ischemia with adipose-derived stem cells in a preclinical Swine model of myocardial infarction.

The aim of the study was to determine the long-term effect of transplantation of adipose-derived stromal cells (ADSCs) in a preclinical model of ischemia/reperfusion (I/R). I/R was induced in 28 Goettingen minipigs by 120 min of coronary artery occlusion followed by reperfusion. Nine days later, surviving animals were allocated to receive transendocardial injection of a mean of 213.6 ± 41.78 million green fluorescent protein (GFP)-expressing ADSCs (n = 7) or culture medium as control (n = 9). Heart function, cell engraftment, and histological analysis were performed 3 months after transplantation. Transplantation of ADSCs induced a statistically significant long-lasting (3 months) improvement in cardiac function and geometry in comparison with control animals. Functional improvement was associated with an increase in angiogenesis and vasculogenesis and a positive effect on heart remodeling with a decrease in fibrosis and cardiac hypertrophy in animals treated with ADSCs. Despite the lack of cell engraftment after 3 months, ADSC transplantation induced changes in the ratio between MMP/TIMP. Our results indicate that transplantation of ADSCs, despite the lack of long-term significant cell engraftment, increases vessel density and prevents adverse remodeling in a clinically relevant model of myocardial infarction, strongly suggesting a paracrine-mediated effect. ADSCs thus constitute an attractive candidate for the treatment of myocardial infarction.

Dietary supplementation with vitamins C and E prevents downregulation of endothelial NOS expression in hypercholesterolemia in vivo and in vitro

Impaired endothelium-dependent vasodilation has been associated with decreased NO bioavailability in hypercholesterolemia. This study aimed to determine whether antioxidant vitamins C and E could improve hypercholesterolemia-derived endothelial dysfunction in the porcine model, and whether observed in vivo results could be reproduced in vitro by incubation of coronary endothelial cells (EC) in the presence of native low-density lipoproteins (LDL). Adult mini-pigs were fed standard (C), cholesterol rich (HC) or cholesterol rich diet supplemented with vitamins C and E (HCV). Endothelium-dependent blood flow increase in response to acetylcholine was determined. Endothelial nitric oxide synthase (eNOS) expression was measured in arterial samples and in EC incubated with LDL isolated from porcine plasma. Vasomotor response to acetylcholine in HC was significantly lower (P<0.05) than control and HCV. There was a significant (P<0.05) decrease in eNOS immunoreactivity in HC, compared with HCV and control. Native LDL from HC, but not from HCV, induced a significant decrease in eNOS expression. Vitamins C and E treatment improved the endothelium-dependent vasomotor capacity and prevented decreased expression of eNOS in hypercholesterolemic pigs. A similar effect could be demonstrated in vitro, by incubation of EC with native LDL, suggesting that the effect of physiologically-modified LDL on eNOS could have a role in recovering vascular function.

Repeated implantation of skeletal myoblast in a swine model of chronic myocardial infarction

AIMS Although transplantation of skeletal myoblast (SkM) in models of chronic myocardial infarction (MI) induces an improvement in cardiac function, the limited engraftment remains a major limitation. We analyse in a pre-clinical model whether the sequential transplantation of autologous SkM by percutaneous delivery was associated with increased cell engraftment and functional benefit. METHODS AND RESULTS Chronically infarcted Goettingen minipigs (n = 20) were divided in four groups that received either media control or one, two, or three doses of SkM (mean of 329.6 x 10(6) cells per dose) at intervals of 6 weeks and were followed for a total of 7 months. At the time of sacrifice, cardiac function was significantly better in animals treated with SkM in comparison with the control group. A significantly greater increase in the DeltaLVEF was detected in animals that received three doses vs. a single dose of SkM. A correlation between the total number of transplanted cells and the improvement in LVEF and DeltaLVEF was found (P < 0.05). Skeletal myoblast transplant was associated with an increase in tissue vasculogenesis and decreased fibrosis (collagen vascular fraction) and these effects were greater in animals receiving three doses of cells. CONCLUSION Repeated injection of SkM in a model of chronic MI is feasible and safe and induces a significant improvement in cardiac function.

Computer probability estimates of angiographic coronary artery disease: transportability and comparison with cardiologists' estimates

A computer algorithm for estimating probabilities of any significant coronary obstruction and triple vessel/left main obstructions was derived, validated, and compared with the assessments of cardiac clinician angiographers. The algorithm performed at least as well as the clinicians when the latter knew the identity of the patients whose angiograms they had decided to perform. The clinicians were more accurate when they did not know the identity of the subjects but worked from tabulated objective data. Referral and value induced bias may affect physician judgment in assessing disease probability. Application of computer aids or consultation with cardiologists not directly involved with patient management may assist in more rational assessments and decision making.

Influence of age on left ventricular contractility

Controversy exists about whether left ventricular (LV) function is affected by aging. Therefore, peak systolic pressure to end-systolic diameter, peak systolic pressure to end-systolic volume, systolic wall stress to fractional shortening and systolic wall stress to end-systolic diameter relations were calculated in the left ventricle of 10 healthy subjects greater than 65 years old (age 70 +/- 4 years) (group B). They were compared with a control group composed by 10 healthy subjects (group A, age 22 +/- 1 years). LV measurements were obtained with M-mode echocardiography and an automatic cuff was used to determine blood pressure. Changes in the load conditions were obtained by 15 mg sublingual isosorbide dinitrate. There were no differences in resting end-systolic diameter, end-systolic volume, end-diastolic diameter, end-diastolic volume, fractional shortening, ejection fraction or systolic wall stress. Older subjects had higher values of resting peak systolic pressure (p less than 0.05) and lower heart rates (p less than 0.05). Young subjects had a steeper peak systolic pressure to end-systolic diameter slope (92 +/- 11 vs 51 +/- 11 mm Hg/cm; p less than 0.001) and peak systolic pressure to end-systolic volume slope (3.4 +/- 0.7 vs 1.9 +/- 0.6 mm Hg/ml; p less than 0.001). There was a slight difference in systolic wall stress to fractional shortening slopes between both groups (group A -0.215 vs group B -0.49%/10(3) dynes/cm2, p = 0.02) but not between systolic wall stress to end-systolic diameter slopes (group A 0.013 vs group B 0.019 cm/10(3) dynes/cm2, difference not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamins C and E attenuate plasminogen activator inhibitor-1 (PAI-1) expression in a hypercholesterolemic porcine model of angioplasty

BACKGROUND The plasminogen activator inhibitor-1 (PAI-1), which modulates fibrinolysis and cell migration, may influence proteolysis and neointimal formation in the arterial wall contributing to restenosis after vascular injury. Antioxidants have been proposed as inhibiting multiple proatherogenic events. We explore the effect of vitamins C and E on PAI-1 expression in an experimental model of angioplasty in hypercholesterolemic pigs. METHODS AND RESULTS A total of 44 Yucatan minipigs were divided into three diet groups: a normal-cholesterol (NC), a high-cholesterol (HC), and a high-cholesterol plus vitamins C+E (HCV) group. Balloon injury was induced in the right internal iliac artery 4 weeks after initiation of either dietary regimen, and plasma and tissue samples were taken at different time periods to measure PAI-1 activity and vascular inhibitor expression. The cholesterol-rich diet induced an increased in vascular PAI-1 expression in the intima, media and adventitia which was markedly reduced in the HCV group. After injury, severe structural changes were observed in NC and HC animals associated with increased systemic PAI-1 activity (P<0.001) and local PAI-1 expression being more intense in HC group. Vitamins C and E significantly reduced plasma PAI-1 activity (P=0.018) and attenuated the inhibitor expression as compared with HC. CONCLUSIONS This experimental study in a porcine model of hypercholesterolemia demonstrates that vitamins C and E reduce local and systemic PAI-1 induced after angioplasty as well as the hypercholesterolemia-induced vascular PAI-1.

Clinical assessment of the probability of coronary artery disease: judgmental bias from personal knowledge.

Probability estimates of angiographic coronary artery disease made by experienced, board- certified staff cardiologists were compared with those of cardiologists in training (fellows). In addition, estimates made before coronary angiography were compared with those made several months later based on written clinical summaries of 15 items of objective clinical and test data. Cardiologists were asked to estimate the probabilities of coronary artery disease, multivessel disease, and triple-vessel or left main disease. The study population consisted of 510 consecutive patients without valvular disease referred for the first time for coronary angiography to three hospitals. Both staff and fellows consistently overestimated the pre-angiographic probability of coronary artery disease. The probabilities estimated from patient summaries were always significantly lower than the pre-angiographic assessments. Only staff cardiologists reliably assessed the probabilities of coronary artery disease during the second assessment (p < 0.05). Thus, estimates of disease probability based on clinical judgment vary according to the source of information, and these estimates are more accurate when physicians have objective data on hand and do not know the identities of the patients. Key words: judgment; disease probability; disease estimate; coronary artery disease; clinical assessment; value-induced bias. (Med Decis Making 1992;12:197-203)

Stress Testing in Patients One Year After Orthotopic Cardiac Transplantation

To evaluate the circulatory re sponse of the denervated heart to ex ercise, the authors studied 15 patients with an orthotopic transplanted heart (TH). Mean age was 48±10 (range twenty-five to sixty-two) years. All patients underwent a symptom-lim ited bicycle stress testing following a continuous protocol increasing the work load by 30 watts every three minutes. Exercise test was performed 16±9 months after operation. Fifteen healthy subjects matched for age were used as the control group. There were significant differences (p < 0.01) in heart rate, at rest, peak exercise, and at five minutes of the recovery period, in maximal oxygen consumption (VO2 max) and in dura tion of exercise between TH patients and controls. Synchronization between recipi ent and donor sinoatrial nodes was observed in 10 of 15 patients. A case of silent myocardial ischemia was also observed in a patient with vascu litis and acute rejection. In conclusion, the lack of neural control in TH patients allows them to maintain a normal resting cardiac output but precludes attaining a nor mal maximum oxygen uptake, de spite a normal contractile state. The high resting heart rate due to para sympathetic denervation constitutes an important limiting factor for an adequate chronotropic reserve. Functional capacity of transplanted patients is slightly impaired, but it does not preclude a good quality of life.

Effect of age on long-term prognosis of patients with myocardial infarction

We studied 181 patients aged under 65 years and 129 patients over 65 with acute myocardial infarction. There were no major differences in the prevalence of coronary risk factors, angina or previous myocardial infarction. A larger percentage of elderly patients had congestive heart failure (51.4% vs 32.6%, P less than 0.001) and complete heart block (17.1% vs 7.2%, P less than 0.01) during the acute phase. In-hospital mortality was significantly higher in the elderly patients (34% vs 16%, P less than 0.01). Late mortality rates correlated in both groups with the Killip class at the time of infarction and with the occurrence of reinfarction. In the elderly group, it was also associated with complete heart block during the acute phase. Five-year survival was 80% in the older and 72% in the younger patients (P = 0.1). Age did not affect survival of Killip class I patients (85% vs 86%, P = 0.83), but life expectancy was significantly reduced in elderly patients in Killip class greater than II (39% vs 60%, P less than 0.05). In conclusion, elderly patients cannot be considered a homogeneous group of high-risk patients. Clinical variables at the time of infarction can identify low- and high-risk subsets among them. Age constitutes an independent prognostic factor for late mortality when any degree of heart failure is present.

The value of exercise testing in patients with coronary artery spasm

To analyze the usefulness of a single exercise test to predict the presence of fixed obstructive coronary artery disease in patients with active coronary spasm, 91 consecutive patients with angiographically proven symptomatic coronary artery spasm who had performed a symptom-limited exercise test within the week before diagnostic coronary angiography were studied. Coronary angiography revealed significant coronary obstructions in 61 patients (67%). According to the type of angina, the prevalence of significant coronary stenosis was 53% for patients with angina at rest, 68% for those with effort angina, and 92% for those with mixed angina. Exercise-induced ST segment elevation was present in eight patients (9%), ST segment depression was seen in 37 patients (41%), and no ST abnormalities in 46 (50%). There was not a significant relationship between the ST segment response to exercise and the clinical variables assessed except for coronary anatomy. Abnormal exercise test results were significantly more frequent in patients with significant coronary obstructions than in those without significant coronary occlusions (62% versus 23%; p less than 0.01). ST elevation was not useful to predict the presence of fixed coronary lesions. However, ST depression strongly suggested the presence of underlying coronary lesions with a sensitivity of 54%, a specificity of 87%, and a positive predictive value of 89%. Using this criterion, 65% of the patients were correctly classified. The results indicate that despite the functional component of ischemia in patients with coronary spasm, ST segment depression with exercise is still a highly specific sign with a high positive predictive value for the presence of significant coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)