Poly(trimethylene carbonate-co-L-lactide) electrospun scaffolds for use as vascular grafts

Currently, there is great clinical need for suitable synthetic grafts that can be used in vascular diseases. Synthetic grafts have been successfully used in medium and large arteries, however, their use in small diameter vessels is limited and presents a high failure rate. In this context, the aim of this study was to develop tissue engineering scaffolds, using poly(trimethylene carbonate-co-L-lactide) (PTMCLLA), for application as small diameter vascular grafts. For this, copolymers with varying trimethylene carbonate/lactide ratios - 20/80, 30/70, and 40/60 - were submitted to electrospinning and the resulting scaffolds were evaluated in terms of their physicochemical and biological properties. The scaffolds produced with PTMCLLA 20/80, 30/70, and 40/60 showed smooth fibers with an average diameter of 771±273, 606±242, and 697±232 nm, respectively. When the degradation ratio was evaluated, the three scaffold groups had a similar molecular weight (Mw) on the final day of analysis. PTMCLLA 30/70 and 40/60 scaffolds exhibited greater flexibility than the PTMCLLA 20/80. However, the PTMCLLA 40/60 scaffolds showed a large wrinkling and their biological properties were not evaluated. The PTMCLLA 30/70 scaffolds supported the adhesion and growth of mesenchymal stem cells (MSCs), endothelial progenitor cells, and smooth muscle cells (SMCs). In addition, they provided a spreading of MSCs and SMCs. Given the results, the electrospun scaffolds produced with PTMCLLA 30/70 copolymer can be considered promising candidates for future applications in vascular tissue engineering.

Células progenitoras endoteliais circulantes em crianças e adolescentes obesos / Circulating endothelial progenitor cells in obese children and adolescents

Resumo Objetivo Investigar a relação entre os números de células progenitoras endoteliais circulantes e a ativação endotelial em uma população pediátrica com obesidade. Métodos Estudo observacional e transversal, que incluiu 120 crianças e adolescentes com obesidade primária de ambos de sexos, entre seis e 17 anos, recrutados de nossa Clínica de Riscos Cardiovasculares. O grupo de controle contou com 41 crianças e adolescentes com índice de massa corporal normal. As variáveis analisadas foram: idade, sexo, índice de massa corporal, pressão arterial sistólica e diastólica, proteína C reativa de alta sensibilidade, perfil lipídico, leptina, adiponectina, resistência à insulina para avaliação do modelo de homeostase, proteína quimiotática de monócitos-1, E-seleticna, dimetilarginina assimétrica e números de células endoteliais progenitoras circulantes. Resultados A resistência à insulina foi correlacionada à dimetilarginina assimétrica (p = 0,340; p = 0,003), que foi diretamente correlacionada, porém de forma muita amena, à E-seleticna (ρ = 0,252; p = 0,046). Não constatamos que a proteína C reativa de alta sensibilidade estivesse correlacionada a marcadores de ativação endotelial. A pressão arterial sistólica foi diretamente correlacionada ao índice de massa corporal ρ = 0,471; p < 0,001) e à resistência à insulina para avaliação do modelo de homeostase (ρ = 0,230; p = 0,012) e inversamente correlacionada à adiponectina (ρ = −0,331; p < 0,001) e à lipoproteína de alta densidade-colesterol ρ = −0,319; p < 0,001). Os números de células progenitoras endoteliais circulantes foram diretamente correlacionados, porém de forma muito amena, ao índice de massa corporal (r = 0,211; p = 0,016), à leptina (ρ = 0,245; p = 0,006), aos níveis de triglicerídeos (r = 0,241; p = 0,031) e à E-seleticna ρ = 0,297; p = 0,004). Conclusão Os números de células progenitoras endoteliais circulantes são elevados em crianças e adolescentes obesos com comprovação de ativação endotelial. Isso sugere que, na infância, os mecanismos de reparação endotelial estão presentes no contexto da ativação endotelial.

Abstract Objective This study aimed to investigate the relationship between circulating endothelial progenitor cell count and endothelial activation in a pediatric population with obesity. Methods Observational and transversal study, including 120 children and adolescents with primary obesity of both sexes, aged 6-17 years, who were recruited at this Cardiovascular Risk Clinic. The control group was made up of 41 children and adolescents with normal body mass index. The variables analyzed were: age, gender, body mass index, systolic and diastolic blood pressure, high-sensitivity C-reactive protein, lipid profile, leptin, adiponectin, homeostasis model assessment-insulin resistance, monocyte chemoattractant protein-1, E-selectin, asymmetric dimethylarginine and circulating progenitor endothelial cell count. Results Insulin resistance was correlated to asymmetric dimethylarginine (ρ = 0.340; p = 0.003), which was directly, but weakly correlated to E-selectin (ρ = 0.252; p = 0.046). High sensitivity C-reactive protein was not found to be correlated to markers of endothelial activation. Systolic blood pressure was directly correlated to body mass index (ρ = 0.471; p < 0.001) and the homeostasis model assessment-insulin resistance (ρ = 0.230; p = 0.012), and inversely correlated to adiponectin (ρ = −0.331; p < 0.001) and high-density lipoprotein cholesterol (ρ = −0.319; p < 0.001). Circulating endothelial progenitor cell count was directly, but weakly correlated, to body mass index (r = 0.211; p = 0.016), leptin (ρ = 0.245; p = 0.006), triglyceride levels (r = 0.241; p = 0.031), and E-selectin (ρ = 0.297; p = 0.004). Conclusion Circulating endothelial progenitor cell count is elevated in obese children and adolescents with evidence of endothelial activation, suggesting that, during infancy, endothelial repairing mechanisms are present in the context of endothelial activation.

Effect of Endogenous Bone Marrow Derived Stem Cells Induced by AMD-3100 on Expanded Ischemic Flap

The purpose of this study was to devise an expanded ischemic flap model and to investigate the role of AMD-3100 (Plerixafor, chemokine receptor 4 inhibitor) in this model by confirming its effect on mobilization of stem cells from the bone marrow. Male Sprague-Dawley rats were used as an animal research model. The mobilization of stem cells from the bone marrow was confirmed in the AMD-3100-treated group. The fractions of endothelial progenitor cells (EPC) and the vascular endothelial growth factor receptor (VEGFR) 2+ cells in the peripheral blood were increased in groups treated with AMD-3100. The expression of vascular endothelial growth factor (VEGF) was increased in response to expansion or AMD injection. The expression of stromal cell derived factor (SDF)-1 and VEGFR2 were increased only in unexpanded flap treated with AMD-3100. Treatment with AMD-3100 increased both the number and area of blood vessels. However, there were no statistically significant differences in the survival area or physiologic microcirculation in rats from the other groups. This endogenous neovascularization induced by AMD-3100 may be a result of the increase in both the area and number of vessels, as well as paracrine augmentation of the expression of VEGF and EPCs. However, the presence of a tissue expander under the flap could block the neovascularization between the flap and the recipient regardless of AMD-3100 treatment and expansion.