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

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.

Fifty-two femoral arteries were distributed in seven groups. In group A (control), 10 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).

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 C1 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.

A modified cryopreservation technique preserves endothelial function independently of the storage time up to 6 months.