Evidence for preservation of epithelial function in cryopreserved porcine and human bronchi

Porcine and human bronchi have been investigated in vitro without or after storage at -196 degrees C in Krebs-Henseleit solution containing 2.0 M dimethyl sulphoxide and 0.1 M sucrose as cryoprotectants. In bronchi from both species maximal post-thaw contractile responses to acetylcholine (ACh) were reduced by about 25-30% compared to unfrozen bronchi. To assess the viability of bronchi and endothelium-denuded rat aortic strips, was employed. The release of an epithelium-derived inhibitory factor (EpDIF) was induced by ACh and assessed in terms of concentration-dependent relaxation of the endothelium-denuded rat aortae. Following removal of bronchial epithelium, ACh failed to elicit any relaxation of rat aorta. With cryopreserved bronchi from both pig and human about 5 and 30 times higher concentrations of ACh, respectively, were required to elicit the same relaxant response as with unfrozen bronchi. The results suggest that after the freezing-thawing process both smooth muscle and epithelial function is largely preserved and provide support for the use of cryopreservation for storage of airway preparations for pharmacological studies.