Improving the attachment and proliferation of umbilical cord mesenchymal stem cells on modified polystyrene by nitrogen-containing plasma.

Wharton's jelly mesenchymal stem cells (WJMSCs) are important alternative source of pluripotent cells for several therapeutic purposes. Understanding of adhesion properties of such cells is necessary to regulate the attachment, growth and proliferation on targeted culture surfaces. BCP-K1, a line of WJMSCs, and polystyrene (PS) culture dishes were used as membrane samples. A 13.56 MHz inductively coupled discharge plasma reactor with a mixture of N-containing gas and noble gas was used. This was expected to introduce the more hydrophilic groups on PS surface and enhance the cell adhesion. The plasma-treated PS dishes with the mixed gas of N(2) + He at 50 W and NH(3) + He at 100 W were reactive towards BCP-K1. Cellular adhesion and proliferation was significantly twice as efficient on the treated surfaces than on PS dishes. BCP-K1 also secreted more focal adhesion kinase to adhere and proliferate when cultured on N(2)-treated PS dishes than on the NH(3)-treated PS dishes. Stable stemness markers were detected, including CD105, CD9 and SSEA-4, expressed on BCP-K1 growing on the modified PS dish surfaces, during 7 days of culturing. The presence of -NH(2) groups on the PS dish surface were revealed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. A large amount of oxygen- and nitrogen-containing functional groups, up to 9.0 %, were introduced by NH(3) plasma and N(2) plasma. The functional groups introduced on to the PS surfaces were clearly the key factors which enhanced WJMSCs attachment and stemness stability.