Neointima in Vascular Prostheses: The Jury is Still Out: Reply

Abstract

We greatly appreciate the remarks of Dr Protopapas and want to comment on them. Synthetic prostheses are successfully applied for the reconstruction of large diameter arteries (>6 mm). However, clinically applied purely synthetic vascular grafts fail in small diameter and low flow locations [1Bordenave L. Remy-Zolghardi M. Fernandez P. Bareille R. Midy D. Clinical performance of vascular grafts lined with endothelial cells.Endothelium. 1999; 6: 267-275Crossref PubMed Scopus (63) Google Scholar]. To overcome this problem, hybrid grafts have been developed from synthetic materials with a bioartificial endothelial lining, and first experiences have been promising. However, the same groups conceded limitations of these tissue engineered constructs, including structural immaturity and suboptimal mechanical properties resulting in unfavorable in vivo results in recent publications [2Hoerstrup SP, Kadner A, Melnitchouk S, et al. Tissue engineering of functional trileaflet heart valves from human marrow stromal cells. Circulation 2002;106(12 Suppl I):I143–50.Google Scholar]. Lessons learned from animal experiments applying hybrid grafts during the last decade are that synthetic scaffolds need physiologic material properties mimicking the native extracellular matrix to allow functional endothelial differentiation and function [3Hubbell J.A. Bioactive biomaterials.Curr Opin Biotechnol. 1999; 10: 123-129Crossref PubMed Scopus (463) Google Scholar]. Currently, no synthetic material is available that can fulfil these demands. On the other hand, biological matrices are available at present and might earlier lead to a new generation of improved (cardio-) vascular substitutes [4Gulbins H. Goldemund A. Uhlig A. Pritisanac A. Meiser B. Reichart B. Implantation of an autologously endothelialized homograft.J Thorac Cardiovasc Surg. 2003; 126: 890-891Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar]. We greatly appreciate the remarks of Dr Protopapas and want to comment on them. Synthetic prostheses are successfully applied for the reconstruction of large diameter arteries (>6 mm). However, clinically applied purely synthetic vascular grafts fail in small diameter and low flow locations [1Bordenave L. Remy-Zolghardi M. Fernandez P. Bareille R. Midy D. Clinical performance of vascular grafts lined with endothelial cells.Endothelium. 1999; 6: 267-275Crossref PubMed Scopus (63) Google Scholar]. To overcome this problem, hybrid grafts have been developed from synthetic materials with a bioartificial endothelial lining, and first experiences have been promising. However, the same groups conceded limitations of these tissue engineered constructs, including structural immaturity and suboptimal mechanical properties resulting in unfavorable in vivo results in recent publications [2Hoerstrup SP, Kadner A, Melnitchouk S, et al. Tissue engineering of functional trileaflet heart valves from human marrow stromal cells. Circulation 2002;106(12 Suppl I):I143–50.Google Scholar]. Lessons learned from animal experiments applying hybrid grafts during the last decade are that synthetic scaffolds need physiologic material properties mimicking the native extracellular matrix to allow functional endothelial differentiation and function [3Hubbell J.A. Bioactive biomaterials.Curr Opin Biotechnol. 1999; 10: 123-129Crossref PubMed Scopus (463) Google Scholar]. Currently, no synthetic material is available that can fulfil these demands. On the other hand, biological matrices are available at present and might earlier lead to a new generation of improved (cardio-) vascular substitutes [4Gulbins H. Goldemund A. Uhlig A. Pritisanac A. Meiser B. Reichart B. Implantation of an autologously endothelialized homograft.J Thorac Cardiovasc Surg. 2003; 126: 890-891Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar].