Mesenchymal stem cells display coordinated rolling and adhesion behavior on endothelial cells.

Area of Science:

• Immunology
• Cell Biology
• Biomedical Engineering

Background:

• Mesenchymal stem cells (MSCs) are promising for cell-based therapies.
• Understanding MSCs' interaction with the vasculature is key for effective transplantation.
• Extravasation, the process of cells leaving the bloodstream, is critical for MSC homing.

Purpose of the Study:

• To investigate the initial molecular interactions between transplanted mesenchymal stem cells (MSCs) and endothelial cells (ECs) during extravasation.
• To elucidate the specific adhesion molecules involved in MSC binding to the vessel wall under flow conditions.

Main Methods:

• Utilized a parallel plate flow chamber to study MSC binding to human umbilical vein endothelial cells (HUVECs) at physiological shear stresses.
• Employed function-blocking antibodies against P-selectin and VCAM-1, and their corresponding ligands (VLA-4) to block specific molecular interactions.
• Conducted intravital microscopy in a mouse model to observe MSC behavior in postcapillary venules in vivo.

Main Results:

• MSCs exhibited rolling and firm adhesion to HUVECs, similar to peripheral-blood mononuclear cells (PBMCs) and CD34(+) progenitors.
• MSC binding and rolling were significantly dependent on P-selectin and VCAM-1/VLA-4 interactions.
• TNF-alpha stimulation of ECs enhanced MSC adhesion.
• In vivo studies confirmed P-selectin-dependent rolling and adhesion of MSCs to venules.

Conclusions:

• Mesenchymal stem cells (MSCs) interact with endothelial cells (ECs) through a coordinated mechanism involving P-selectin and VCAM-1/VLA-4 during extravasation.
• These findings provide critical insights into the homing mechanisms of MSCs and can inform strategies for optimizing cell-based therapies.