Changes in the cooling rate and medium improve the vascular function in cryopreserved porcine femoral arteries

Purpose: The purpose of this study was to design an adequate technique with which to cryopreserve pig femoral arteries and to assess the influence of storage times in vascular function. Methods: Fifty-two femoral arteries were distributed in seven groups. In group A (control), TO arteries were studied after harvest; in groups B1 and B2, 19 arteries were suspended in RPMI 1640 plus fetal calf serum plus dimethylsulfoxide and were cryopreserved at 1 degrees C per minute or 0.3 degrees C per minute, respectively. In groups C1 to C4, 23 arteries were suspended in modified Krebs-Henseleit plus dimethylsulfoxide plus sucrose, cryopreserved at 0.7 degrees C per minute, and kept frozen for 1, 15, 60, or 180 days, respectively. After being thawed, arteries were examined for contraction and endothelial-dependent vasodilation (organ bath studies), antithrombotic properties of the endothelial layer(perfusion studies), and vessel structure (electron microscopy). Results: Endothelial cells were present in both cryopreserved and control arteries. The control vessels showed a mean contraction to norepinephrine (10(-7) mol/L) of 13010 +/- 3181 mg. Arteries in groups B1 and B2 did not respond to norepinephrine. Contraction in groups CT to C4 was as follows: C1, 5354 +/- 1222 mg; C2, 5187 +/- 2672 mg; C3, 6867 +/- 2292 mg; C4, 7000 +/- 2858 mg, which represent 50% of the control values (P <.001). Vasodilation was similar in control (99% +/- 3%) and cryopreserved arteries (C1, 90% +/- 13%; C2, 93% +/- 12%; C3, 89%:, +/- 15%; C4, 88% +/- 22%). Storage time did not influence vascular function. Platelet interaction was almost absent and similar in all groups. Conclusion: A modified cryopreservation technique preserves endothelial function independently of the storage time up to 6 months.