Delivery of cardiovascular progenitors with biomimetic microcarriers reduces adverse ventricular remodeling in a rat model of chronic myocardial infarction.

Despite tremendous progress in cell-based therapies for heart repair, many challenges still exist. To enhance the therapeutic potential of cell therapy one approach is the combination of cells with biomaterial delivery vehicles. Here, we developed a biomimetic and biodegradable micro-platform based on polymeric microparticles (MPs) capable of maximizing the therapeutic potential of cardiac progenitor cells (CPCs) and explored its efficacy in a rat model of chronic myocardial infarction. The transplantation of CPCs adhered to MPs within the infarcted myocardial microenvironment improved the long-term engraftment of transplanted cells for up to one month. Furthermore, the enhancement of cardiac cellular retention correlated with an increase in functional recovery. In consonance, better tissue remodeling and vasculogenesis were observed in the animals treated with cells attached to MPs, which presented smaller infarct size, thicker right ventricular free wall, fewer deposition of periostin and greater density of vessels than animals treated with CPCs alone. Finally, we were able to show that part of this beneficial effect was mediated by CPC-derived extracellular vesicles (EVs). Taken together, these findings indicate that the biomimetic microcarriers support stem cell survival and increase cardiac function in chronic myocardial infarction through modulation of cardiac remodeling, vasculogenesis and CPCs-EVs mediated therapeutic effects. The biomimetic microcarriers provide a solution for biomaterial-assisted CPC delivery to the heart. STATEMENT OF SIGNIFICANCE: In this study, we evaluate the possibility of using a biomimetic and biodegradable micro-platform to improve cardiovascular progenitor therapy. The strategy reported herein serves as an injectable scaffold for adherent cells due to their excellent injectability through cardiac catheters, capacity for biomimetic three-dimensional stem cell support and controllable biodegradability. In a rat model of chronic myocardial infarction, the biomimetic microcarriers improved cardiac function, reduced chronic cardiac remodeling and increased vasculogenesis through the paracrine signaling of CPCs. We have also shown that extracellular vesicles derived from CPCs cultured on biomimetic substrates display antifibrotic effects, playing an important role in the therapeutic effects of our tissue-engineered approach. Therefore, biomimetic microcarriers represent a promising and effective strategy for biomaterial-assisted CPC delivery to the heart.

Tissue factor expressed by microparticles is associated with mortality but not with thrombosis in cancer patients.

A prothrombotic state is one of the hallmarks of malignancy and a major contributor to morbidity and mortality in cancer patients.Tissue factor (TF) is often overexpressed in malignancy and is a prime candidate in predicting the hypercoagulable state. Moreover, increased number of TF-exposing microparticles (MPs) in cancer patients may contribute to venous thromboembolism (VTE). We have conducted a prospective cohort study to determine whether elevated TF antigen, TF activity and TF associated to MPs (MPs-TF) are predictive of VTE and mortality in cancer patients. The studied population consisted of 252 cancer patients and 36 healthy controls. TF antigen and activity and MPs-TF were determined by ELISA and chromogenic assays. During a median follow-up of 10 months, 40 thrombotic events were recorded in 34 patients (13.5%), and 73 patients (28.9%) died. TF antigen and activity were significantly higher in patients than in controls (p<0.01) mainly in patients with advanced stages, whereas no differences were observed for TF activity of isolated MPs. We did not find a statistically significant association of TF variables with the risk of VTE. Multivariate analysis adjusting for age, sex, type of cancer and other confounding variables showed that TF activity (p<0.01) and MPs-TF activity (p<0.05) were independently associated with mortality. In conclusion, while TF variables were not associated with future VTE in cancer patients, we found a strong association of TF and MPs-TF activity with mortality, thus suggesting they might be good prognostic markers in cancer patients.

Arterial and venous thrombosis is associated with different angiogenic cytokine patterns in patients with antiphospholipid syndrome.

Antiphospholipid syndrome (APS) is defined as a combination of antiphospholipid antibodies, arterial and/or venous thrombosis, and, in women, recurrent fetal loss. The mechanisms underlying this prothrombotic tendency are unclear. Here we determined plasma levels of the angiogenic growth factors vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and stromal cell-derived factor-1 (SDF-1) in 34 patients with APS (median age 40 years) compared with 180 healthy controls and with 80 age-matched deep-venous thrombosis patients in whom the diagnosis of APS had been excluded. All of the patients met updated APS criteria and two-thirds of them were triply positive for antiphospholipid antibodies (lupus anticoagulant, anti-beta2-glycoprotein I and anti-cardiolipin antibodies). Angiogenic cytokines were quantified at least 6 months after an acute thrombotic event. VEGF levels were similar in the patients and controls, but were significantly higher in the patients with arterial thrombosis than in the patients with venous thrombosis. Plasma levels of SDF-1 and PlGF were significantly elevated in the patients, regardless of the arterial/venous nature of the thrombosis. Together, these results suggest that APS is associated with an angiogenic process, but that the angiogenic signal differs between patients with arterial and venous thrombosis. Lupus (2010) 19, 837-843.

Development of targeted angiogenic medicine.

Strategies to alter angiogenesis have been successfully translated from the bench to bedside. With an estimated number of more than 500 million patients worldwide potentially benefiting from it, it is a prime example of targeted therapy that is increasingly changing the face of clinical medicine. Most efforts to stimulate or inhibit angiogenesis in the past were focused on the key angiogenic factor vascular endothelial growth factor (VEGF), resulting in the approval by the Food and Drug Administration of several drugs for the treatment of cancer and ocular disease. However, mounting clinical evidence reveals that inhibition of VEGF causes resistance and class-specific side effects, while therapeutic angiogenesis by delivering VEGF protein is more challenging than anticipated in human patients. Hence, alternatives are needed, and modulation of oxygen-sensitive enzymes (prolyl hydroxylase domain proteins) and of hypoxia induced transcription factors has recently emerged as a potential novel strategy to treat cancer and ischemic diseases. Furthermore, placental growth factor is a disease-specific angiogenic target, whose inhibition reduces cancer growth without causing major side effects, while its delivery induces revascularization of ischemic tissues. In this review, we summarize recent developments and discuss questions that arise in the exciting, rapidly developing field of angiogenic medicine, including a brief description of its possible implications in neurodegenerative diseases.

Beneficial effects of prolonged systemic administration of PlGF on late outcome of post-ischaemic myocardial performance.

Recent evidence indicates that an imbalance between cardiomyocyte hypertrophy and blood vessel growth in the remote myocardium may contribute to heart failure in ischaemic heart disease. It remains, however, largely unknown which angiogenic factors are capable of stimulating vessel growth in the remote myocardium after myocardial infarction (MI) and whether systemic, rather than local, administration of such factors suffices to ameliorate post-MI cardiac recovery. We therefore analysed the effect of systemic placental growth factor (PlGF) delivery on myocardial recovery post-MI in mice. MI was induced by permanent ligation of the left anterior descending coronary (LAD) artery in C57Bl6/J mice, followed by systemic injection of a PlGF adenovirus, resulting in elevated circulating levels of PlGF for 4 weeks. Functional and morphological analysis revealed that PlGF treatment induced cardiomyocyte hypertrophy and improved cardiac recovery at day 28 post-MI. PlGF stimulated angiogenesis in the infarct border and vessel enlargement in the remote myocardium. In this mouse model, capillary-to-cardiomyocyte ratios in the remote myocardium were maintained post-MI, but PlGF increased the vascular perfusion area in balance with the cardiomyocyte hypertrophy. Overall, systemic delivery of PlGF improves cardiac performance and promotes adaptive remodelling of the post-MI heart.

Independent association of matrix metalloproteinase-10, cardiovascular risk factors and subclinical atherosclerosis.

OBJECTIVES: Circulating levels of matrix metalloproteinase (MMP)-10 are related to inflammation in asymptomatic subjects with cardiovascular risk factors. Whether MMP-10 is associated with the severity of atherosclerosis remains to be determined. This study examines the relationship of systemic MMP-10 levels with atherosclerotic risk factors and subclinical atherosclerosis. METHODS AND RESULTS: Circulating levels of MMP-1, -9 and -10, and markers of inflammation [fibrinogen, interleukin-6, von Willebrand factor, and high-sensitivity C-reactive protein (hs-CRP)] were measured in 400 subjects (mean age 54.3 years, 77.7% men) with cardiovascular risk factors but free from clinical cardiovascular disease. Subclinical atherosclerosis was evaluated by both the mean carotid intima-media thickness (IMT) and the presence of atherosclerotic plaques with the use of B-mode ultrasound in all subjects. MMP-10 levels were positively correlated with fibrinogen (r = 0.24, P < 0.001), hs-CRP (r = 0.14, P < 0.01) and carotid IMT (r = 0.17, P < 0.01). The association between MMP-10 and IMT remained significant in multiple regression analysis (P < 0.02) when controlling for traditional atherosclerotic risk factors and inflammatory markers. Such an association was not observed for MMP-1 and -9. Subjects in the highest MMP-10 tertile had significantly higher carotid IMT (adjusted odds ratio 6.3, 95% confidence interval 1.3-31.4, P = 0.024). In addition, MMP-10 levels were significantly higher in patients with carotid plaques (n = 78) than in those with no plaques after adjusting for age and sex (P < 0.01). CONCLUSION: Higher serum MMP-10 levels were associated with inflammatory markers, increased carotid IMT and atherosclerotic plaques in asymptomatic subjects. Circulating MMP-10 may be useful to identify subclinical atherosclerosis in subjects free from cardiovascular disease.

Protective effect of the G-765C COX-2 polymorphism on subclinical atherosclerosis and inflammatory markers in asymptomatic subjects with cardiovascular risk factors.

BACKGROUND: Cyclooxygenase (COX)-2, a key regulatory enzyme in prostanoid synthesis, plays an important role in inflammatory processes. The -765G>C COX-2 polymorphism has been associated with lower promoter activity in vitro and reduced levels of C-reactive protein (CRP) in atherosclerotic carriers of the C allele. However, its pathophysiological relevance in vivo has not been fully elucidated. METHODS AND RESULTS: We assessed the -765G>C polymorphism and COX-2 expression in 220 asymptomatic subjects free of cardiovascular disease, in relation to global vascular risk, carotid intima-media thickness (IMT), and inflammatory markers (fibrinogen, C-reactive protein [CRP], von Willebrand factor [vWF] and interleukin-6 [IL-6]). Genotype frequencies were: CC (7.7%), CG (34.5%), GG (57.7%). Among hypercholesterolemic subjects (n=140), C allele carriers had lower COX-2 expression (p<0.05), reduced carotid IMT (p<0.01) and diminished levels of inflammatory markers CRP, vWF and IL-6 (p<0.05), as compared to GG homozygous subjects. The association between carotid IMT and COX-2 polymorphism remained significant after adjusting for cardiovascular risk factors and inflammatory markers (p=0.008). CONCLUSIONS: In asymptomatic hypercholesterolemic subjects the C allele of -765G>C COX-2 polymorphism was associated with lower COX-2 expression, and reduced subclinical atherosclerosis and systemic inflammation compared with GG homozygous, thus conferring atherosclerosis protection in this cardiovascular risk population.

Different expression of MMPs/TIMP-1 in human atherosclerotic lesions. Relation to plaque features and vascular bed.

BACKGROUND: Proteolytic imbalance might determine arterial remodeling and plaque destabilization in atherosclerotic vessels. The aim of this study was to examine differences in the patterns of metalloproteinases (MMPs) and MMP inhibitor (TIMP-1) expression in advanced human atheromas, both in relation to the plaque features and the vascular bed involved. METHODS AND RESULTS: Immunohistochemistry for MMP-1, -3, -9 and TIMP-1 as well as the collagen content were measured in vascular sections from patients undergoing peripheral revascularization (carotid n=11, femoral n=23) and aorto-coronary bypass surgery (mammary arteries n=20, as controls). Increased expression of all MMPs was detected in atherosclerotic as compared with control sections (P<0.01). Aneurysmal plaques showed a significant increase of MMP-1 and-3 and a reduction in total collagen (P<0.05) in relation to occlusive lesions. Calcification areas in atherosclerotic plaques were consistently associated with increased TIMP-1 expression (P<0.01). Finally, MMP-9 expression was higher in occlusive lesions from carotid than femoral arteries (P<0.01). CONCLUSIONS: Aneurysm lesions expressed higher MMP-1 and-3 expression than occlusive plaques, and MMP-9 was mainly detected in carotid as compared with femoral arteries. TIMP-1 was associated with arterial calcification. These differences in the MMPs/TIMP-1 expression might determine the evolution of advanced atherosclerotic plaques and contribute to its vulnerability.