title: HOXB4 but not BMP4 confers self-renewal properties to ES-derived hematopoietic progenitor cells.
abstract: BACKGROUND
  Achieving transplantation tolerance remains an unresolved clinical challenge. Although bone marrow transplantation (BMT) induces mixed chimerism that establishes transplantation tolerance, the preconditioning regimens required for BMT to succeed are too prohibitive for routine use. Recently, embryonic stem (ES) cells have emerged as a potential alternative cell source to bone marrow cells. However, it remains difficult to efficiently differentiate these cells into hematopoietic cells. Here, we tested whether bone morphogenetic protein-4 (BMP-4)-treated or HOXB4-transduced ES-derived hematopoietic cells engraft permanently inducing long-term mixed chimerism.
  
  
  METHODS
  Initially, 129 SvJ R1 ES cells (H-2) were treated with BMP-4 for 36 hr. The cells were phenotyped and polymerase chain reaction studies were performed. The robustness of mixed chimerism was tested using mixed lymphocyte cultures and skin grafts. Chimeric MRL (H-2) animals received grafts from 129SvJ (H-2), Balb/c (H-2) or class II (H-2) donor mice, and graft survival was monitored. Additionally, HOXB4-transduced ES cells were shown to more efficiently differentiate into hematopoietic progenitor cells that engrafted in allogenic and syngeneic recipient mice.
  
  
  RESULTS
  BMP-4 treatment induced Sca-1 expression and up-regulated HOXB4, BMP-4, and BMP receptor gene expressions. The cells induced transient mixed chimerism, whereas cells derived from HOXB4-transduced ES cells engrafted long term (>100 days).
  
  
  CONCLUSIONS
  Although BMP-4 promotes hematopoiesis of ES cells, its impact is only transient, whereas permanent ectopic expression of HOXB4 significantly confers self-renewal and long-term engraftment of ES-derived hematopoietic cells. This strategy could facilitate the establishment of an alternative source of hematopoietic cells that could induce transplantation tolerance.
authors.affiliation: Department of Internal Medicine, University of Iowa Hospitals and Clinics and VA Medical Center, Iowa City, IA 52242, USA.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Bonde
authors.forename: Amy M
authors.initials: AM
authors.lastname: Dowden
authors.forename: Kun-Ming
authors.initials: KM
authors.lastname: Chan
authors.forename: William B
authors.initials: WB
authors.lastname: Tabayoyong
authors.forename: Nicholas
authors.initials: N
authors.lastname: Zavazava
mesh_terms: D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000494:pharmacology*; D018929:Cell Culture Techniques; D002460:Cell Line; D017931:DNA Primers; D017930:Genes, Reporter; D006410:Hematopoiesis / Q000187:drug effects / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D018398:Homeodomain Proteins / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D016133:Polymerase Chain Reaction; D016038:Skin Transplantation / Q000502:physiology; D014157:Transcription Factors / Q000494:pharmacology*; D018183:Transplantation Chimera; D023001:Transplantation Tolerance / Q000187:drug effects / Q000502:physiology*
chemical_list: C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D017931:DNA Primers; D000949:Histocompatibility Antigens Class II; D018398:Homeodomain Proteins; C513262:Hoxb4 protein, mouse; D014157:Transcription Factors