ABSTRACT
<p><b>OBJECTIVE</b>To investigate the biological characteristics and genetic features of human placenta mesenchymal stem cells (hPA-MSCs) cultured in vitro in order to assess its safety for clinical use.</p><p><b>METHODS</b>The shapes of the 1st, 3rd, 5th, 7th, 10th, 13th, 17th and 20th generation hPA-MSCs cultured in vitro using serum-free culture medium were observed. Their cell cycle, cell surface markers, and karyotype were analyzed, and relevant genes and cytokines were measured.</p><p><b>RESULTS</b>The shape of hPA-MSCs has remained as fusiform or short fusiform, and there was no significant change. About 93% of hPA-MSCs cells were in G0/G1 phase and remained stable. No obvious chromosomal translocation, loss or inversion was noted by karyotyping analysis. Cytokines expression level remained stable. Related gene expression level as a whole was on the decline, but the gene expression level of the first five generations showed very slight variations, with genetic characteristics remaining stable.</p><p><b>CONCLUSION</b>The hPA-MSCs cultured in vitro with serum-free medium has retained stable in the first five generations.</p>