Repopulation of freeze-dried porcine valves with human fibroblasts and endothelial cells.
OBJECTIVE
There is a need for a replacement cardiac valve constructed from non-immunogenic materials but incorporating living, and preferably autologous, cells. The object of this study was to colonize freeze-dried porcine valve leaflets with human fibroblasts and vascular endothelial cells.


METHODS
Porcine pulmonary valve leaflets were freeze-dried to produce a porous matrix having communicating cavities of appropriate dimensions for fibroblast repopulation. Cultured human fibroblasts and vascular endothelial cells that had been cryopreserved by standard methods were added to freeze-dried leaflets. Following culture at 37 degrees C, the leaflets were examined by confocal scanning microscopy and transmission electron microscopy.


RESULTS
Mechanical perforation of the leaflet surface permitted colonization of the freeze-dried matrix by fibroblasts; under the conditions we studied, the cell density did not reach physiologic levels but those cells that were present were well attached and metabolically active. Gentle cotton abrasion of the surface of the freeze-dried leaflets provided a suitable substrate for endothelial cell attachment and confluence was achieved in 10 days. Leaflets were perforated, cultured with human fibroblasts for 10 days, then gently rubbed with a cotton bud and cultured for a further 10 days with human endothelial cells. The endothelial cells formed a confluent layer on the surface and viable fibroblasts were present within the substance of the leaflet.


CONCLUSIONS
Although these results are preliminary, they demonstrate the basic feasibility of this approach to the production of xenogeneic valves that contain the patient's own cells.
Curtil
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Medical Cryobiology Unit, Department of Biology, University of York, UK.
Pegg
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Wilson
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D000818:Animals; D001705:Bioprosthesis; D002478:Cells, Cultured; D015925:Cryopreservation; D004727:Endothelium / Q000166:cytology* / Q000648:ultrastructure; D005347:Fibroblasts / Q000166:cytology* / Q000648:ultrastructure; D005612:Freeze Drying / Q000379:methods*; D006350:Heart Valve Prosthesis; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D011664:Pulmonary Valve; D013499:Surface Properties; D013552:Swine