Double labelling of human umbilical cord mesenchymal stem cells with G d‐ DTPA and PKH 26 and the influence on biological characteristics of h UCMSC s

Summary The aim of this study was to determine whether double labelling of human umbilical cord mesenchymal stem cells (hUCMSCs) with gadolinium‐diethylene triamine penta‐acetic acid ( G d‐ DTPA ) and PKH 26 influences their biological characteristics. A tissue adherence technique was used to separate and purify the h UCMSC s and flow cytometry was performed to detect the surface markers expressed on them. G d‐ DTPA and PKH 26 were used to label the stem cells and MRI and fluorescence microscopy were used to detect the double‐labelled h UCMSC s. A MTT assay was used to delineate the growth curve. Transmission electron microscopy ( TEM ) and atomic force microscopy were used to demonstrate the ultrastructural features of the hUCMSCs. Flow cytometry showed that h UCMSC s highly expressed CD 29, CD 90, CD 44 and CD 105. No expression of CD 31, CD 34 and CD 45 was detected. Very low expression of HLA ‐ DR and CD 40 was detected. Atomic force microscopy showed these cells were long, spindle shaped, and the cytoplasm and nucleus had clear boundaries. After double labelling, TEM showed G d particles aggregated in the cytoplasm in a cluster pattern. The proliferation activity, cell cycle, apoptosis and differentiation of the stem cells were not influenced by double labelling. Thus a tissue adherence technique is helpful to separate and purify h UCMSC s effectively; and G d‐ DTPA and PKH 26 are promising tracers in the investigation of migration and distribution of h UCMSC s in vivo .