title: Gene therapy for bladder pain with gene gun particle encoding pro-opiomelanocortin cDNA.
abstract: OBJECTIVE
  Interstitial cystitis is a bladder hypersensitivity disease associated with bladder pain that has been a major challenge to understand and treat. We hypothesized that targeted and localized expression of endogenous opioid peptide in the bladder could be useful for the treatment of bladder pain. Pro-opiomelanocortin (POMC) is one of such precursor molecules. In this study we developed a gene gun method for the transfer of POMC cDNA in vivo and investigated its therapeutic effect on acetic acid induced bladder hyperactivity in rats.
  
  
  METHODS
  Human POMC cDNA was cloned into a modified pCMV plasmid and delivered into the bladder wall of adult female rats by direct injection or the gene gun. Three days after gene therapy continuous cystometrograms were performed using urethane anesthesia by filling the bladder (0.08 ml per minute) with saline, followed by 0.3% acetic acid. Bladder immunohistochemical testing was used to detect endorphin after POMC cDNA transfer.
  
  
  RESULTS
  The intercontraction interval was decreased after intravesical instillation of acetic acid (73.1% or 68.1% decrease) in 2 control groups treated with saline or the gene gun without POMC cDNA, respectively. However, rats that received POMC cDNA via the gene gun showed a significantly decreased response (intercontraction interval 35% decreased) to acetic acid instillation, whereas this antinociceptive effect was not detected in the plasmid POMC cDNA direct injection group. This effect induced by POMC gene gun treatment was reversed by intramuscular naloxone (1 mg/kg), an opioid antagonist. Increased endorphin immunoreactivity with anti-endorphin antibodies was observed in the bladder of gene gun treated animals.
  
  
  CONCLUSIONS
  The POMC gene can be transferred in the bladder using the gene gun and increased bladder expression of endorphin can suppress nociceptive responses induced by bladder irritation. Thus, POMC gene gun delivery may be useful for the treatment of interstitial cystitis and other types of visceral pain.
authors.affiliation: Department of Urology, Chang Gung Memorial Hospital, Kaohsiung, Taiwan, Republic of China.
authors.forename: Yao-Chi
authors.initials: YC
authors.lastname: Chuang
authors.forename: A-K
authors.initials: AK
authors.lastname: Chou
authors.forename: P-C
authors.initials: PC
authors.lastname: Wu
authors.forename: Po-Hui
authors.initials: PH
authors.lastname: Chiang
authors.forename: T-J
authors.initials: TJ
authors.lastname: Yu
authors.forename: L-C
authors.initials: LC
authors.lastname: Yang
authors.forename: Naoki
authors.initials: N
authors.lastname: Yoshimura
authors.forename: Michael B
authors.initials: MB
authors.lastname: Chancellor
mesh_terms: D000818:Animals; D019470:Biolistics / Q000379:methods*; D018856:Cystitis, Interstitial / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D018076:DNA, Complementary / Q000235:genetics*; D004723:Endorphins / Q000378:metabolism; D005260:Female; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D017288:Pain Threshold / Q000187:drug effects; D017699:Pelvic Pain / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D011333:Pro-Opiomelanocortin / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D001743:Urinary Bladder / Q000473:pathology
chemical_list: D018076:DNA, Complementary; D004723:Endorphins; D011333:Pro-Opiomelanocortin