Effects of cryopreservation on the immunogenicity of porcine arterial allografts in early stages of transplant vasculopathy.
BACKGROUND
The number of revascularization procedures including coronary and lower extremity bypass, have increased greatly in the last decade. It suggests a growing need for vascular grafts. Cryopreserved allografts could represent a viable alternative but their immunologic reactivity remains controversial.


METHODS
71 pigs (40 recipients and 31 donors) were used. Two femoral grafts per recipient animal were implanted for 3, 7, and 30 days. Types of grafts: fresh autograft as a control graft (n=19), fresh allograft (n=31) and cryopreserved allograft (n=30). Histological and immunohistochemical studies were performed.


RESULTS
Fresh allografts compared to autografts showed intimal inflammatory infiltration at 3 days (328 vs. 0 macrophages/mm2; P<0.05) and 7 days (962 vs. 139 T lymphocytes/mm2; P<0.05) post-transplantation. At 30 days, there was a loss of endothelial cells, presence of luminal thrombus and aneurismal lesions (total area=15.8 vs. 8.4 mm2; P<0.05). Cryopreservation did not reduce these lesions nor modify endothelial nitric oxide synthase (eNOS) expression nor modify the number of animals that developed anti-SLA antibodies. Moreover, at 7 days, cryopreserved allografts compared to fresh allografts showed a higher expression of P-selectin (5 out of 5 vs. 1 out of 5; P<0.05) and, at 30 days, a greater inflammatory reactivity (2692 vs. 1107 T lymphocytes/mm2 in media; P<0.05) with a trend towards a higher presence of multinucleated giant cells than in the fresh ones.


CONCLUSIONS
The cryopreservation method used maintained immunogenicity of allografts and increased the inflammatory reactivity found in fresh allografts up to 30 days of vascular transplantation.
Solanes
Núria
N
Institut de Malalties Cardiovasculars, IDIBAPS (Institut d'Investigacions Biomèdiques Agustí Pi Sunyer), Barcelona, Spain. nsolanes@clinic.ub.es
Rigol
Montserrat
M
Khabiri
Ebrahim
E
Castellà
Manuel
M
Ramírez
José
J
Roqué
Mercè
M
Agustí
Elba
E
Roig
Eulàlia
E
Pérez-Villa
Fèlix
F
Segalés
Joaquim
J
Pomar
José Luís
JL
Engel
Pablo
P
Massaguer
Anna
A
Martorell
Jaume
J
Rodríguez
Jose Antonio
JA
Sanz
Ginés
G
Heras
Magda
M
D000783:Aneurysm / Q000473:pathology; D000818:Animals; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D005263:Femoral Artery / Q000276:immunology* / Q000473:pathology / Q000637:transplantation*; D006098:Granulocytes / Q000187:drug effects / Q000276:immunology; D007518:Isoantibodies / Q000276:immunology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D052250:Nitric Oxide Synthase Type III / Q000096:biosynthesis; D019007:P-Selectin / Q000096:biosynthesis; D013552:Swine; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D013927:Thrombosis / Q000473:pathology; D013997:Time Factors; D014181:Transplantation Immunology; D014182:Transplantation, Autologous / Q000276:immunology / Q000379:methods; D014184:Transplantation, Homologous / Q000276:immunology* / Q000379:methods
D003451:Cryoprotective Agents; D007518:Isoantibodies; D019007:P-Selectin; D052250:Nitric Oxide Synthase Type III