PURPOSE:Cryotherapy has been employed in the treatment of disease for many years. We sought to evaluate CryoSpray Ablation(CSA) in the airway of swine to determine the safety and feasibility of CSA in human airways.
METHODS:CSA was used to treat three groups of healthy swine. Groups 1 and 2 received 4,5 second cryo-treatments and were sacrificed on Days 7 and 28 respectively. Group 3 received 2, 5 second cryo-treatments and were sacrificed on Day 7. Full thickness histological inspection was preformed by a blinded expert pathologist. Depth of cryo-induced injury and tissue regeneration were assessed at Days 7 and 28 and compared to control.
RESULTS:No adverse events occurred. The cryospray effect was confined to the treatment site and to a lesser extent, the contra-lateral region of the treated bronchus. Full thickness specimens showed injury reached the cartilaginous layer (3mm). Mucosal injury and re-epithelialization were noted in all groups, but damage and subsequent healing of the cartilage in Groups 1 and 2 was of most interest. As an epiphenomenon, chondrogenesis was noted on Day 28 as compared to Day 7, despite identical treatments. Day 7 specimen showed gross hyaline cartilage damage, including massive cellular death and cartilaginous blanching. Day 28 specimens showed markedly less cartilage damage and improved vascularity, leading to the possible conclusion of regeneration. Day 28 pericondrium looked to be differentiating into a cartilaginous layer, perhaps trying to fix the injury inflicted by the CSA treatment.
CONCLUSION:This trial demonstrates the safety and efficacy of cryotherapy in swine, and suggests feasibility for the treatment of human lung disease. As an incidental discovery of CSA in the airway, the relative lack of cartilage damage seen in Group 3 as compared to Groups 1 and 2 suggest 2 cycles of 5 second spray might be useful in human palliation. Further studies would be needed to clarify and quantify these results.
CLINICAL IMPLICATIONS:CSA may be effective for treatment of human lung disease.
DISCLOSURE:William Krimsky, University grant monies No; Grant monies (from sources other than industry) No; Grant monies (from industry related sources) No; Shareholder No; Employee No; Fiduciary position (of any organization, association, society, etc, other than ACCP No; Consultant fee, speaker bureau, advisory committee, etc. Consultant-Chair of Scientific Advisory Board; Other No; No Product/Research Disclosure Information