Ann Thorac Surg 2006;81:64
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Invited commentary
Dörthe Schmidt, MD,
Simon P. Hoerstrup, MD, PhD
Clinic for Cardiovascular Surgery, University Hospital Zurich, Ramistrasse 100, Zurich, CH 8032 Switzerland
(Email: doerthe.schmidt{at}chi.usz.ch; simon_philipp.hoerstrup{at}chi.usz.ch).
The article by Yang and colleagues [1] describes another important attempt to overcome the limitations of currently available prosthetic materials. Using tissue engineering technologies, the in vitro fabrication of living human cardiovascular patches for future applications in cardiovascular surgery is demonstrated. Tissue engineering represents a novel experimental approach to create autologous, living replacements with the potential to grow, regenerate, and remodel. In particular the pediatric patients with congenital defects would greatly benefit from growing replacement materials by reducing the need for surgical reinterventions due to the lack of prosthetic material growth. The presented concept of tissue engineering is based on autologous cells, seeded onto biodegradable scaffolds followed by tissue formation and maturation of the cell seeded constructs in vitro.
The main focus of this article is on the improvement of the in vitro culture conditions by the use of a pulsatile bioreactor. In accordance with previous studies of this group and others, it is clearly demonstrated that in vitro conditioning of engineered tissues in a bioreactive system stimulates and enhances the production of extracellular matrix and the related tissue strength.
Although representing an important step toward the clinical realization of the tissue engineering concept, several questions remain. To which extent are the mechanical properties achieved by the described process a result of neo-tissue formation versus residual polymeric scaffold material? This question will be of particular importance with regard to the safety of the tissue engineered patches beyond full scaffold biodegradation as well as their applicability for high pressure situations. So far the majority of tissue engineered constructs was only used in low pressure situations (eg, for the reconstruction of the right ventricular outflow tract). Furthermore, since no endothelialization of the patches was seen, their functionality with regard to the absence of thrombogenicity will have to be demonstrated in future in vivo studies. In principal, the ideal cell source for cardiovascular tissue engineering is not defined yet. The pediatric aorta-derived cells used in this study will not be clinically relevant in an autologous concept. However, recent studies have demonstrated in vitro generation of cardiovascular patches based on blood-derived progenitor cells and umbilical cord tissue-derived cells, representing a clinically more feasible autologous cell source.
These questions clearly go beyond the scope of this study. The authors have to be congratulated for their current achievements and should be encouraged to validate their results in appropriate in vivo models.
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References
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- Yang C, Sodian R, Fu P, et al. In vitro fabrication of a tissue engineered human cardiovascular patch for future use in cardiovascular surgery Ann Thorac Surg 2006;81:57-64.[Abstract/Free Full Text]
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