title: Recovery of the injured external anal sphincter after injection of local or intravenous mesenchymal stem cells.
abstract: OBJECTIVE
  To understand the endogenous process of wound healing after anal sphincter injury and to determine possible mechanisms by which mesenchymal stem cells (MSCs) exert their regenerative potential.
  
  
  METHODS
  Virginal female rats (n=204) underwent anal sphincter laceration and repair. Thereafter, animals were randomly assigned to control injection, injection with intravenous MSCs, or direct injection of MSCs into the injured sphincter. Twenty uninjured animals served as baseline controls. Sphincters were analyzed for contractile function and parameters of wound healing 24 hours, 48 hours, 7 days, and 21 days after injury.
  
  
  RESULTS
  Direct injection of MSCs into the injured anal sphincter resulted in improved contractile function 21 days after injury compared with controls. Although expression of both proinflammatory (cyclooxygenase-2 and interleukin-6) and anti-inflammatory (interleukin-10 and tumor necrosis factor-α-stimulated gene-6) genes were increased dramatically and transiently after injury, MSCs did not alter this response. In contrast, transforming growth factor (TFG)-β1 (an important mediator of matrix deposition by mesenchymal cells) and lysyl oxidase (an enzyme important for synthesis of collagen and elastin) expression increased dramatically at earlier time points in the direct MSC injection group compared with controls. Increased expression of TFG-β1 and lysyl oxidase in directly injected sphincters was associated with increased collagen deposition and engraftment of MSCs in the sphincter.
  
  
  CONCLUSIONS
  In this preclinical animal model, direct, but not intravenous, injection of MSCs into the injured anal sphincter at the time of repair resulted in improved contractile function of the sphincter after injury, increased matrix deposition in the external anal sphincter, and increased expression of TFG-β1 and lysyl oxidase in the acute phase after injury.
authors.affiliation: ProPath Laboratory, and Division of Female Pelvic Medicine and Reconstructive Surgery, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9032, USA.
authors.forename: Sujatha D
authors.initials: SD
authors.lastname: Pathi
authors.forename: Jesus F
authors.initials: JF
authors.lastname: Acevedo
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Keller
authors.forename: Annavarapu H
authors.initials: AH
authors.lastname: Kishore
authors.forename: Rodney T
authors.initials: RT
authors.lastname: Miller
authors.forename: Clifford Y
authors.initials: CY
authors.lastname: Wai
authors.forename: R Ann
authors.initials: RA
authors.lastname: Word
mesh_terms: D001003:Anal Canal / Q000293:injuries* / Q000502:physiology; D000818:Animals; D051546:Cyclooxygenase 2 / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D005260:Female; D015552:Injections, Intralesional; D007275:Injections, Intravenous; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D008249:Protein-Lysine 6-Oxidase / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D020127:Recovery of Function; D014945:Wound Healing
chemical_list: D016207:Cytokines; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat; D008249:Protein-Lysine 6-Oxidase