Biological safety of human skin-derived stem cells after long-term in vitro culture

Abstract

The aim of this study was to investigate the biological safety of human skin-derived mesenchymal stem cells (HSMSCs) cultured in vitro by detecting changes in karyotype, major histocompatibility complex expression and tumorigenicity. Before the 21st passage of the in vitro culture, cell surface markers were analysed by flow cytometry; major histocompatibility complex expression was detected by RT-PCR and flow cytometry. The tumorigenicity of HSMSCs was tested using SCID mice and observing changes in the injection site and pathological sections. Flow cytometry demonstrated that HSMSCs express CD73, CD105 and vimentin, but haematopoietic markers CD34, CD45 and CD19 were not expressed. Human leukocyte antigen (HLA-I and HLA-DR) mRNA was detected by RT-PCR; the protein expression of HLA-I was 29.5-31.7%, but HLA-DR protein expression was not detected in HSMSCs. The result of karyotype analysis before the 21st passage was normal and tumour formation was not detected in the mice. Taken as a whole, our results suggest that HSMSCs cultured in vitro may be safely transplanted in vivo, due to moderate expression of HLA-I and low expression of HLA-DR, non-tumorigenicity and normal karyotype.