Aim
Hematopoietic stem cells, especially CD117pos 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 (AT2R) can lead to further cell differentiation and receptor auto‐expression and might thus influence electrophysiological properties of CD117pos stem cells. This study was designed to functionally characterize membrane currents of CD117pos cells under normal and AT2R‐stimulated conditions.
Methods
CD117pos murine bone marrow stem cells were isolated with MACS technique and stimulated for the AT2R 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 CD117pos 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 AT2R‐stimulated cells inward rectifying the hyperpolarization‐induced inward currents were slightly attenuated on the translational level but showed increased mRNA expression. Cultured CD117pos cells express CD31 and VEGFR‐2 and significantly increased the uptake of acLDL.
Conclusions
CD117pos cells do not have properties of action potential–generating cells and moderately change their excitability during AT2R stimulation. Electrophysiological and molecular properties of control and AT2R‐stimulated cells point to a differentiation to vascular endothelial cells. This could increase beneficial vascularization in injured tissues.