Collagen is the most widely distributed class of proteins in the human body. The use of collagen-based biomaterials in the field of tissue engineering applications has been intensively growing over the past decades. Multiple cross-linking methods were investigated and different combinations with other biopolymers were explored in order to improve tissue function. Collagen possesses a major advantage in being biodegradable, biocompatible, easily available and highly versatile. However, since collagen is a protein, it remains difficult to sterilize without alterations to its structure. This review presents a comprehensive overview of the various applications of collagen-based biomaterials developed for tissue engineering, aimed at providing a functional material for use in regenerative medicine from the laboratory bench to the patient bedside.

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Collagen-Based Biomaterials for Tissue Engineering Applications

Vascular tissue engineering: towards the next generation vascular grafts.

Aortic valve disease and treatment: The need for naturally engineered solutions ☆

Background—Degeneration of xenografts or homografts is a major cause for reoperation in young patients after pulmonary valve replacement. We present the early results of fresh decellularized pulmonary homografts (DPH) implantation compared with glutaraldehyde-fixed bovine jugular vein (BJV) and cryopreserved homografts (CH). Methods and Results—Thirty-eight patients with DPH in pulmonary position were consecutively evaluated during the follow-up (up to 5 years) including medical examination, echocardiography, and MRI. These patients were matched according to age and pathology and compared with BJV (n=38) and CH (n=38) recipients. In contrast to BJV and CH groups, echocardiography revealed no increase of transvalvular gradient, cusp thickening, or aneurysmatic dilatation in DPH patients. Over time, DPH valve annulus diameters converge toward normal z-values. Five-year freedom from explantation was 100% for DPH and 86±8% and 88±7% for BJV and CH conduits, respectively. Additionally, MRI investigations in 17...

Use of Fresh Decellularized Allografts for Pulmonary Valve Replacement May Reduce the Reoperation Rate in Children and Young Adults: Early Report

Objective: The longevity of valved right ventricle to pulmonary artery (RV-PA) conduits is limited due to calcification and degeneration of nonviable structures. Xenografts are commonly used because of the restricted availability of cryopreserved homografts. Tissue-engineered (decellularised) pulmonary valves (TEPVs) were thought to be a valuable alternative to cryopreserved pulmonary homografts due to postoperative seeding with viable autologous vascular endothelial cells. Methods: From July 2007 to December 2008, xenogenous TEPV (Matrix P plus#) were implanted in 16patients in the rightventricular outflowtract for differentindications, relatedto congenitalheart disease.Mean age at operation was 14 11 years, including three patients younger than 1 year. The median conduit size was 22 mm (range: 13—26 mm). Results: The early and late survival rates were 100%. At a median follow-up of 10 months (range: 2—17 months), six patients (38%) had to be re-operated upon due to obstructed grafts. Five of these patients were older than 13 years (range: 13—26 years); one patient was younger than 1 year. On echocardiography before re-operation, mean systolic gradient in the main PA was 66 18 mmHg. In explanted conduits, we found a predominantly peripheral conduit narrowing without leaflet calcification. Histological examination revealed stenosis formation, due to inflammatory infiltration and severely fibrogenic pseudo-intimal reaction. Conclusions: On the basis of our short-term results, the Matrix P plus# de-cellularised tissueengineered pulmonary valve cannot be regarded as an ideal conduit for right ventricular outflow tract reconstruction, as the widespread use of these grafts may increase the possibility of frequent early conduit failures. # 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

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Takeshi Konuma

Papers

Performance of CryoValve SG decellularized pulmonary allografts compared with standard cryopreserved allografts.