Use of arginine-glycine-aspartic acid adhesion peptides coupled with a new collagen scaffold to engineer a myocardium-like tissue graft.

BACKGROUND: Cardiac tissue engineering might be useful in treatment of diseased myocardium or cardiac malformations. The creation of functional, biocompatible contractile tissues, however, remains challenging. We hypothesized that coupling of arginine-glycine-aspartic acid-serine (RGD+) adhesion peptides would improve cardiomyocyte viability and differentiation and contractile performance of collagen-cell scaffolds. METHODS: Clinically approved collagen scaffolds were functionalized with RGD+ cells and seeded with cardiomyocytes. Contractile performance, cardiomyocyte viability and differentiation were analyzed at days 1 and 8 and/or after culture for 1 month. RESULTS: The method used for the RGD+ cell-collagen scaffold coupling enabled the following features: high coupling yields and complete washout of excess reagent and by-products with no need for chromatography; spectroscopic quantification of RGD+ coupling; a spacer arm of 36 A, a length reported as optimal for RGD+-peptide presentation and favorable for integrin-receptor clustering and subsequent activation. Isotonic and isometric mechanical parameters, either spontaneous or electrostimulated, exhibited good performance in RGD+ constructs. Cell number and viability was increased in RGD+ scaffolds, and we saw good organization of cell contractile apparatus with occurrence of cross-striation. CONCLUSIONS: We report a novel method of engineering a highly effective collagen-cell scaffold based on RGD+ peptides cross-linked to a clinically approved collagen matrix. The main advantages were cell contractile performance, cardiomyocyte viability and differentiation.

[Enlarging angioplasty of the aortic arch with an pulmonary artery autograft patch. Interest in a single-stage repair of the syndrome of coarctation and interruption of the aortic arch]. / Angioplastie d'agrandissement de la crosse aortique par un patch d'autogreffe pulmonaire. Intérêt dans la réparation en un temps des syndromes de coarctation et interruption de l'arche aortique.

Single stage repair of syndromes of coarctation and interruption of the aortic arch is a routine procedure in many surgical centres with good immediate results. The classical technique of aortic repair is based on the principles of Crafoord's extended resection anastomosis. Recoarctation is not an unusual long-term complication. A technique of enlarging angioplasty of the aorta using a patch of pulmonary artery has been developed and used in 22 neonates with obstruction of the aortic arch associated with ventricular septal defect with an average age and body weight of 15 days and 2.9 Kg respectively. The ventricular septal defect was closed surgically during the same procedure. Total circulatory arrest was not used in these children and all had aortic repairs with selective cerebral perfusion with moderate hypothermia (28-30 degrees C). This technique was used without any procedure-related early morbidity. No early or late deaths were observed in this series. Two patients were reoperated during the first year after the initial procedure: one for residual ventricular septal defect and the other for supraventricular pulmonary stenosis. Two patients, one of whom was reoperated, developed supraventricular pulmonary stenosis with a gradient of over 60 mmHg. These stenoses were observed in the first cases operated and were essentially due to the technique of pulmonary artery reconstruction. Over a median follow-up period of 10 months, no recoarctations were observed: the Doppler ultrasound study showed an isolated mean systolic gradient of 6 +/- 12 mmHg. The authors conclude that angioplasty of the aortic arch with an enlarging patch of pulmonary artery autograft during single stage surgery of syndromes of coarctation and interruption of the aortic arch provides a harmonious and durable repair of the aortic arch.