Elastomeric Fibrous Hybrid Scaffold Supports In Vitro and In Vivo Tissue Formation.

Biomimetic materials with biomechanical properties resembling those of native tissues while providing an environment for cell growth and tissue formation, are vital for tissue engineering (TE). Mechanical anisotropy is an important property of native cardiovascular tissues and directly influences tissue function. This study reports fabrication of anisotropic cell-seeded constructs while retaining control over the construct's architecture and distribution of cells. Newly synthesized poly-4-hydroxybutyrate (P4HB) is fabricated with a dry spinning technique to create anelastomeric fibrous scaffold that allows control of fiber diameter, porosity, and rate ofdegradation. To allow cell and tissue ingrowth, hybrid scaffolds with mesenchymalstem cells (MSCs) encapsulated in a photocrosslinkable hydrogel were developed. Culturing the cellularized scaffolds in a cyclic stretch/flexure bioreactor resulted in tissue formation and confirmed the scaffold's performance under mechanical stimulation. In vivo experiments showed that the hybrid scaffold is capable of withstanding physiological pressures when implanted as a patch in the pulmonary artery. Aligned tissue formation occurred on the scaffold luminal surface without macroscopic thrombus formation. This combination of a novel, anisotropic fibrous scaffold and a tunable native-like hydrogel for cellular encapsulation promoted formation of 3D tissue and provides a biologically functional composite scaffold for soft-tissue engineering applications.

Percutaneous atrial septal defect closure in Ebstein's anomaly.

We report a patient with Ebstein's anomaly, on chronic milrinone therapy for right ventricular failure, who underwent palliative percutaneous closure of her atrial septal defect (ASD) due to recurring strokes. Repeated evaluation of right-sided pressures was performed prior to ASD closure to determine if our patient could tolerate the intervention. Definitive ASD closure was performed under fluoroscopic and transesophageal echocardiogram guidance.

Electrospun PGS:PCL microfibers align human valvular interstitial cells and provide tunable scaffold anisotropy.

Tissue engineered heart valves (TEHV) can be useful in the repair of congenital or acquired valvular diseases due to their potential for growth and remodeling. The development of biomimetic scaffolds is a major challenge in heart valve tissue engineering. One of the most important structural characteristics of mature heart valve leaflets is their intrinsic anisotropy, which is derived from the microstructure of aligned collagen fibers in the extracellular matrix (ECM). In the present study, a directional electrospinning technique is used to fabricate fibrous poly(glycerol sebacate):poly(caprolactone) (PGS:PCL) scaffolds containing aligned fibers, which resemble native heart valve leaflet ECM networks. In addition, the anisotropic mechanical characteristics of fabricated scaffolds are tuned by changing the ratio of PGS:PCL to mimic the native heart valve's mechanical properties. Primary human valvular interstitial cells (VICs) attach and align along the anisotropic axes of all PGS:PCL scaffolds with various mechanical properties. The cells are also biochemically active in producing heart-valve-associated collagen, vimentin, and smooth muscle actin as determined by gene expression. The fibrous PGS:PCL scaffolds seeded with human VICs mimick the structure and mechanical properties of native valve leaflet tissues and would potentially be suitable for the replacement of heart valves in diverse patient populations.

Predictors of reintervention after repair of interrupted aortic arch with ventricular septal defect.

BACKGROUND: Left ventricular outflow tract obstruction after neonatal repair of interrupted aortic arch with ventricular septal defect may warrant reintervention. We sought to identify clinical and preoperative echocardiographic predictors of reintervention for postoperative left ventricular outflow tract obstruction. METHODS: Retrospective data were collected on neonates with interrupted aortic arch with ventricular septal defect who underwent single-stage repair from 1995 to 2009. Univariate and multivariate analyses were performed to identify predictors of reintervention. RESULTS: Seventy patients underwent repair, with 16 patients requiring reintervention: 8 underwent surgical reintervention, 5 underwent percutaneous reintervention, and 3 underwent both. The median time to reintervention was 1.2 years (range, 0.2 to 7.7). All surgical reoperations involved subaortic resection, and all percutaneous reinterventions included balloon aortic valve dilation. Several preoperative echocardiographic measurements were significant by univariate analysis; however, smaller preoperative aortic root size was an independent predictor (p = 0.02) by multivariate analysis. Patients with an aortic root size less than 6.5 mm were at greater risk for reintervention compared with patients with a root size greater than 6.5 mm (reintervention rate 44% and 12%, respectively; p < 0.001). Postoperative left ventricular outflow tract gradient by echocardiogram before discharge was significantly higher in the reintervention group. CONCLUSIONS: Preoperative aortic root size predicts reintervention for postoperative left ventricular outflow tract obstruction after single-stage repair of interrupted aortic arch with ventricular septal defect. Patients with elevated left ventricular outflow tract gradients at discharge are at higher risk of having progressive obstruction and require closer follow-up to ensure early identification and management.