Methods and devices for epithelial protection during photodynamic therapy

Abstract

Methods for preventing damage to epithelial tissue during PDT induced using a photosensitizing agent or pre-photosensitizing agent are provided. The methods of the present invention utilize spatial confinement to control photoactivation of the photoactive species to protect the epithelial tissue. In one embodiment, epithelial tissue surrounding a targeted treatment site can be protecting by decreasing the oxygen-content in the tissue, thereby preventing the conversion of the photosensitizer into the phototoxic species in the epithelial tissue.

1 . A device for protecting non-targeted tissue during photodynamic therapy induced using a photosensitizing agent or a pre-photosensitizing agent, comprising: 
 a tissue-contacting member adapted to decrease local circulation and delivery of oxygenated blood to non-targeted tissue, at least a portion of the tissue-contacting member being transparent to allow light from an irradiating light source to pass therethrough during photodynamic therapy.    
   
   
       2 . The device of  claim 1 , wherein the tissue-contacting member comprises a housing having a chamber formed therein and adapted to be positioned in communication with non-targeted tissue.  
   
   
       3 . The device of  claim 2 , further comprising a vacuum coupled to the chamber for creating a vacuum force within the chamber to reduce blood flow to the non-targeted tissue.  
   
   
       4 . The device of  claim 3 , wherein the tissue-contacting member is further adapted to deform the non-targeted tissue to inhibit blood flow to the tissue.  
   
   
       5 . The device of  claim 4 , further comprising a porous material formed on a tissue-contacting portion of the housing such that, when a vacuum force is creating within the chamber, the non-targeted tissue deforms around the porous material.  
   
   
       6 . The device of  claim 5 , wherein the porous material comprises a wire mesh material.  
   
   
       7 . The device of  claim 2 , further comprising a nitrogen source coupled to the chamber for flushing the non-targeted tissue with nitrogen.  
   
   
       8 . The device of  claim 1 , further comprising a light source coupled to the tissue-contacting member for delivering irradiating light to the non-targeted tissue.