Poly-L-lactic acid (PLLA) nanofibers were fabricated by electrospinning and treated with O-2 plasma. The surface properties of PLLA nanofibers before and after plasma treatment were characterized by water contact angle measurement and X-ray photoelectron spectroscopy (XPS). It was found that the hydrophilicity of PLLA nanofibers was improved and the amount of oxygen-containing groups increased after plasma treatment. Initial cell adhesion was evaluated by cell capture efficiency based on the cell count method. The results showed that initial porcine mesenchymal stem cells (pMSCs) adhesion to plasma-treated nanofibers was significantly enhanced. Moreover, the morphology of pMSCs on PLLA nanofibers (PLLA NFS) and plasma-treated PLLA nanofibers (P-PLLA NFS) were observed by scanning electron microscope (SEM) after 10 min, 20 min, 30 min and 60 min cell adhesion. It was found that plasma treatment to electrospun nanofibers had a great effect on pMSCs morphology at earlier time points. Therefore, plasma treatment is an efficient surface modification strategy to improve cell adhesion in earlier culture time intervals. It may be a promising method in the design of novel tissue-engineered scaffolds. (C) 2013 Elsevier B.V. All rights reserved.