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J Thorac Cardiovasc Surg 1994;108:987-988
© 1994 Mosby, Inc.

LETTERS TO THE EDITOR

Cryopreserved heart valve allografts can have a normal endothelium

Division of Cardiac Surgery
Children's Hospital and Medical Center
Division of Cardiothoracic Surgery
Department of Surgery
University of Washington Medical Center
Seattle, WA 98105

Reply to the Editor:

On behalf of our coauthors, we would like to express our appreciation to Dr. Mohan and his associates for their interest in our work. ¹ Dr. Mohan is correct that we did not demonstrate how well endothelium can bepreserved in the experimental setting. Instead, we attempted to define how well it ispreserved in our usual clinical practice.

We believe that Yankah and associates did demonstrate viability of endothelial cells on cryopreserved allografts. Yankah's use of alcian blue exclusion, although not without its limitations, is recognized as a useful marker of cell viability. ² Yankah and colleagues ^3,4 did not use anti-factor VIII staining to confirm these cells as endothelium. However, using the same method of cell harvesting used by Yankah's group, we observed that most of these cells are in fact endothelium in both human ¹ and animal tissues. ⁵ Factor VIII staining may actually be an inappropriate method for identifying human cardiac valve endothelium. ⁶

Dr. Mohan and his colleagues are to be congratulated for cryopreserving porcine valves in a fashion that results in both morphologic integrity and persistence of in vitro function. ⁷ These techniques may indeed result in superior graft longevity. However, we question Dr. Mohan's statement, "Cryopreservation must aim to preserve a viable endothelial lining . . . ." A viable endothelial lining may result in a stronger host immune response, as pointed out by us in our article and by Dr. Mohan's group in their earlier work. ⁷ Such a host response may actually reduce graft longevity.

We also question Dr. Mohan's assertion that "a lack of viable endothelium" suggests that "preservation of the remaining valve may also then be suspect." This statement contradicts Dr. Mohan's previous publication, which states that "a procedure which allows better preservation of endothelial viability may or may not lead to better fibroblast survival." ⁷ As shown by van der Kampand associates, ⁸ whom Dr. Mohan cites, fibroblasts and endothelium do not necessarily demonstrate a parallel response to preservation techniques.

Again, we thank Dr. Mohan and associates for their thoughtful analysis of our paper. We look forward to their continued basic investigations and eventual clinical trials in this area.

References

1. Lupinetti FM, Tsai TT, Kneebone JM, Bove EL. The effect of cryopreservation on the presence of endothelial cells of human valve allografts. J THORAC CARDIOVASC SURG 1993;106:912-7.[Abstract]
   
2. Thornthwaite JT, Leif RC. A permanent cell viability assay using alcian blue. Stain Technol 1978;53:199-204.[Medline]
   
3. Yankah AC, Dreyer W, Wottge HU, Muller-Rucholtz W, Bernhard A. Kinetics of endothelial cells of preserved aortic valve allografts used for heterotopic transplantation in inbred rat strains. In: Bodnar E, Yacoub MH, eds. Biologic and bioprosthetic valves. New York: Yorke Medical Books, 1986:73-84.
   
4. Yankah AC, Wottge HU, Muller-Hermelink HK, et al. Transplantation of aortic and pulmonary allografts, enhanced viability of endothelial cells by cryopreservation, importance of histocompatibility. J Cardiac Surg 1987;1(suppl):209-20.
   
5. Lupinetti FM, Tsai TT, Kneebone JM. Endothelial cell replication in an in vivo model of aortic allografts. Ann Thorac Surg 1993;56:237-41.[Abstract]
   
6. Simon A, Zavazava N, Sievers HH, Muller-Ruchholtz W. In vitro cultivation and immunogenicity of human cardiac valve endothelium. J Cardiac Surg 1993;8:656-65.[Medline]
   
7. Feng X-J, van Hove CE, Mohan R, et al. Improved endothelial viability of heart valves cryopreserved by a new technique. Eur J Cardiothorac Surg 1992;6:251-5.[Abstract]
   
8. van der Kamp AWM, Visser WJ, van Dongen JM, Nauta J, Galjaard H. Preservation of aortic heart valves with maintenance of cell viability. J Surg Res 1981;30:47-56.[Medline]
   

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Flavian M. Lupinetti Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lupinetti, F. M. Articles by Kneebone, J. M. Search for Related Content PubMed Articles by Lupinetti, F. M. Articles by Kneebone, J. M.