Cellular expression of PCNA and procollagen in vital and ethanol-treated autologous pericardial implants in sheep.

BACKGROUND AND AIMS OF THE STUDY: Cardiovascular surgeries involving repair or reconstruction of heart valve leaflets with vital autologous pericardium have shown detrimental healing outcomes, mainly fibrosis with retraction. It is proposed that cells intrinsic to the pericardial implants may contribute to this fibrosis by becoming activated to proliferate and synthesize type I collagen. METHODS: Vital and ethanol-treated autologous pericardium were implanted as rectangular flaps bisecting the lumen in the descending aorta of sheep to simulate a heart valve leaflet. Implants recovered at 5, 10, 15, and 30 days were evaluated immunohistologically for expression of PCNA and procollagen. RESULTS: In ethanol-treated pericardium, concentrations of activated cells shifted from the fibrin layers on the periphery of implants at days 5 and 10 to cells internal to the implant at days 15 and 30. In contrast, concentrations of activated cells in vital pericardium shifted from cells within the implants at days 5 and 10 to the fibrin deposits overlaying the implants at days 15 and 30. CONCLUSION: Different distributional patterns of activated cells were observed between vital and ethanol-treated pericardial flap implants. These different patterns may be important in understanding the cause of the detrimental healing outcome observed with vital autologous pericardial flap implants.