Mesenchymal stem cell marker Stro-1 is a 75 kd endothelial antigen

Area of Science:

• Immunology
• Cell Biology
• Histology

Background:

• Stro-1 is widely recognized as a marker for mesenchymal stem cells (MSCs).
• Previous research has indicated Stro-1 expression in endothelial cells, prompting further investigation.

Purpose of the Study:

• To clarify the expression pattern of Stro-1 in various tissues and cell types.
• To determine if Stro-1 is an intrinsic endothelial antigen or a marker primarily for MSCs.

Main Methods:

• Immunofluorescence (IF) staining for Stro-1 and von Willebrand Factor (vWF) in liver, lung, and kidney tissues.
• IF staining in cultured endothelial cells.
• Western blot analysis of Stro-1 expression in various cell lines (endothelial cells, smooth muscle cells, fibroblasts, B cells, cancer cell lines, ADSCs).

Main Results:

• Stro-1 and vWF co-expressed in the endothelium of central veins and hepatic sinusoids (liver).
• Stro-1 was present in lung alveolar capillaries where vWF was absent; both expressed in pulmonary blood vessels.
• Stro-1 expression was scant in renal glomeruli compared to strong vWF expression.
• Western blot confirmed a 75 kDa Stro-1 band in endothelial cells and cancer cell lines, but not in other cell types.
• Adipose-derived stem cells (ADSCs) showed increased Stro-1 expression post-culture or upon endothelial differentiation.

Conclusions:

• Stro-1 is intrinsically an endothelial antigen.
• Its expression in mesenchymal stem cells (MSCs) is likely an induced phenomenon, not a defining characteristic.