title: Teratoma formation in immunocompetent mice after syngeneic and allogeneic implantation of germline capable mouse embryonic stem cells.
abstract: BACKGROUND
  Embryonic stem cells (ESCs) have the potential to form teratomas when implanted into immunodeficient mice, but data in immunocompetent mice are limited. We therefore investigated teratoma formation after implantation of three different mouse ESC (mESC) lines into immunocompetent mice.
  
  
  METHODS
  BALB/c mice were injected with three highly germline competent mESCs (129Sv, BALB/c and C57BL/6) subcutaneously or under the kidney capsule. After 4 weeks, mice were euthanized and examined histologically for teratoma development. The incidence, size and composition of teratomas were compared using Pearson Chi-square, t-test for dependent variables, one-way analysis of variance and the nonparametric Kruskal- Wallis analysis of variance and median test.
  
  
  RESULTS
  Teratomas developed from all three cell lines. The incidence of formation was significantly higher under the kidney capsule compared to subcutaneous site and occurred in both allogeneic and syngeneic mice. Overall, the size of teratoma was largest with the 129Sv cell line and under the kidney capsule. Diverse embryonic stem cell-derived tissues, belonging to the three embryonic germ layers, were encountered, reflecting the pluripotency of embryonic stem cells. Most commonly represented tissues were nervous tissue, keratinizing stratified squamous epithelium (ectoderm), smooth muscle, striated muscle, cartilage, bone (mesoderm), and glandular tissue in the form of gut- and respiratory-like epithelia (endoderm).
  
  
  CONCLUSIONS
  ESCs can form teratomas in immunocompetent mice and, therefore, removal of undifferentiated ESC is a pre-requisite for a safe use of ESC in cell-based therapies. In addition the genetic relationship of the origin of the cell lines to the ability to transplant plays a major role.
authors.affiliation: Stem Cell Unit, Department of Anatomy, College of Medicine, King Saud University and King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia E-mail : a.aldahmash@gmail.com, ammahmood@ksu.edu.sa.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Aldahmash
authors.forename: Muhammad
authors.initials: M
authors.lastname: Atteya
authors.forename: Mona
authors.initials: M
authors.lastname: Elsafadi
authors.forename: May
authors.initials: M
authors.lastname: Al-Nbaheen
authors.forename: Husain Adel
authors.initials: HA
authors.lastname: Al-Mubarak
authors.forename: Radhakrishnan
authors.initials: R
authors.lastname: Vishnubalaji
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Roalle
authors.forename: Suzan
authors.initials: S
authors.lastname: Al-Harbi
authors.forename: Muthurangan
authors.initials: M
authors.lastname: Manikandan
authors.forename: Klaus Ingo
authors.initials: KI
authors.lastname: Matthaei
authors.forename: Amer
authors.initials: A
authors.lastname: Mahmood
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013724:Teratoma / Q000473:pathology*