title: Erythropoietin (EPO) influences colonic anastomotic healing in a rat model by modulating collagen metabolism.
abstract: BACKGROUND
  Anastomotic failure is one of the most frequent complications in abdominal surgery. During anastomotic healing. the strength of the intestinal tissue nearby is closely related to the accumulation of collagen in interlinked scar tissue. This in turn is influenced, among other things, by single groups of matrixmetalloproteinases, especially collagenases (MMP-1, -8, and -13) and gelatinases (MMP-2 and -9). EPO is known to induce the expression of tissue-inhibitor-of-matrixmetalloproteinases-1 (TIMP-1) and thereby to down-regulate MMPs.
  
  
  METHODS
  We used a rat as an experimental model and applied a high dose of EPO (5U/g BW s.c.), one dose 24 h before operation (as pre-conditioning) and one dose directly after performing a colonic anastomosis. After 3 and after 5 d, respectively, immunohistochemical stainings for MMP-2, -8, and -9 as well as TIMP-1 were carried out and evaluated semiquantitatively for each layer of the colonic wall. Sirius-red staining and cross-polarization microscopy were evaluated and the collagen I/III ratio calculated. Anastomotic and colonic tissue distal to the anastomosis were used to determine collagen content.
  
  
  RESULTS
  We found increased bursting pressure 5 d post-surgery after applying erythropoietin. It was thus shown that EPO influences collagen metabolism and changes the collagen I/III ratio in the colon distal to the anastomosis. The evaluation of immunohistochemistry did not show the expected ubiquitous up-regulation of TIMP-1 and down-regulation of MMPs. Nevertheless, correlations between TIMP-1, MMP-8, and collagen I/III ratio could only be established after the application of EPO.
  
  
  CONCLUSIONS
  Contrary to our hypothesis, the picture of TIMP-1 and of the regulation of the MMPs after the application of EPO is not as clear as expected. EPO improves anastomotic bursting strength and the correlation of TIMP-1, MMP-8, and collagen type I/III ratio can only be seen after the application of EPO.
authors.affiliation: Department of Surgery, Medical Faculty, Rheinish-Westphalian Technical University, Aachen, Germany. dkaemmer@ukaachen.de
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Kaemmer
authors.forename: Jens
authors.initials: J
authors.lastname: Otto
authors.forename: Marcel
authors.initials: M
authors.lastname: Binneboesel
authors.forename: Christian
authors.initials: C
authors.lastname: Klink
authors.forename: Carsten
authors.initials: C
authors.lastname: Krones
authors.forename: Marc
authors.initials: M
authors.lastname: Jansen
authors.forename: Christian
authors.initials: C
authors.lastname: Cloer
authors.forename: Alexander
authors.initials: A
authors.lastname: Oettinger
authors.forename: Volker
authors.initials: V
authors.lastname: Schumpelick
authors.forename: Uwe
authors.initials: U
authors.lastname: Klinge
mesh_terms: D000714:Anastomosis, Surgical; D000818:Animals; D003094:Collagen / Q000378:metabolism*; D003106:Colon / Q000601:surgery*; D004921:Erythropoietin / Q000494:pharmacology*; D006454:Hemoglobins / Q000032:analysis; D007150:Immunohistochemistry; D008297:Male; D020782:Matrix Metalloproteinases / Q000032:analysis; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000032:analysis; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D006454:Hemoglobins; D011994:Recombinant Proteins; D019715:Tissue Inhibitor of Metalloproteinase-1; D004921:Erythropoietin; D003094:Collagen; D020782:Matrix Metalloproteinases