title: Characterization of ion currents of murine CD117(pos) stem cells in vitro and their modulation under AT2 R stimulation.
abstract: OBJECTIVE
  Hematopoietic stem cells, especially CD117(pos) cells, have been found to possess a regenerative potential in various tissues, in particular cardiac muscle. However, the characterization of the relevant ion currents of stem cells prior to implantation lacks documentation. Activation of angiotensin II type 2 receptor (AT2 R) can lead to further cell differentiation and receptor auto-expression and might thus influence electrophysiological properties of CD117(pos) stem cells. This study was designed to functionally characterize membrane currents of CD117(pos) cells under normal and AT2 R-stimulated conditions.
  
  
  METHODS
  CD117(pos) murine bone marrow stem cells were isolated with MACS technique and stimulated for the AT2 R with angiotensin II and losartan for 3-5 days prior to patch-clamp measurements. RT-PCR was used to determine channel expression. Endothelial properties were analysed with immunocytochemistry and acLDL uptake assay.
  
  
  RESULTS
  A well-expressed inward rectifying current (IKir ) was identified in cultured CD117(pos) cells. Furthermore, a ZD 7288 (HCN channel blocker)-sensitive current component was isolated. Voltage-dependent potassium currents and chloride currents were less expressed. A small fraction of cells demonstrated voltage- and time-dependent inward currents. In AT2 R-stimulated cells inward rectifying the hyperpolarization-induced inward currents were slightly attenuated on the translational level but showed increased mRNA expression. Cultured CD117(pos) cells express CD31 and VEGFR-2 and significantly increased the uptake of acLDL.
  
  
  CONCLUSIONS
  CD117(pos) cells do not have properties of action potential-generating cells and moderately change their excitability during AT2 R stimulation. Electrophysiological and molecular properties of control and AT2 R-stimulated cells point to a differentiation to vascular endothelial cells. This could increase beneficial vascularization in injured tissues.
authors: Reference and Translation Centre for Cardiac Stem Cell Therapy, University Rostock, Rostock, Germany.
authors: M
authors: M
authors: Ludwig
authors: A
authors: A
authors: Skorska
authors: A
authors: A
authors: Tölk
authors: H-H
authors: HH
authors: Hopp
authors: R
authors: R
authors: Patejdl
authors: J
authors: J
authors: Li
authors: G
authors: G
authors: Steinhoff
authors: T
authors: T
authors: Noack
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D002454:Cell Differentiation / Q000502:physiology; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology; D006321:Heart / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology*; D066298:In Vitro Techniques; D008077:Lipoproteins, LDL / Q000493:pharmacokinetics; D019808:Losartan / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000502:physiology*; D019009:Proto-Oncogene Proteins c-kit / Q000502:physiology*; D011743:Pyrimidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D044139:Receptor, Angiotensin, Type 2 / Q000502:physiology*; D012038:Regeneration / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D002316:Cardiotonic Agents; D008077:Lipoproteins, LDL; D024661:Potassium Channels, Inwardly Rectifying; D011743:Pyrimidines; D012333:RNA, Messenger; D044139:Receptor, Angiotensin, Type 2; D014662:Vasoconstrictor Agents; C032629:acetyl-LDL; D000804:Angiotensin II; C082246:ICI D2788; D019009:Proto-Oncogene Proteins c-kit; D019808:Losartan