Objective       To determine lentiviral vector integration sites in human keratinocytes

and to make a preliminary analysis of lentiviral vector integration preference in human epidermal cells.       Methods       Ligation-mediated PCR (LM-PCR) was used to clone integration site sequences of lentiviral vector in the genome of transfected human immortalized keratinocyte line from our previous study. After the cloned DNA fragments were sequenced

the sequence reads were inputted into the online tool GTSG-QuickMap as requested and mapped in the human genome to get the integration sites. The integration preference of lentiviral vector in human keratinocytes was analyzed in view of the relationship between integration sites distribution and chromosomes

genes and transcription start sites.       Results       A total of 1 148 positive transformants were sequenced and analyzed

and 199 unique integration sites were obtained. As compared with the matched random control simulated by GTSG-QuickMap

the integration frequencies of lentiviral vector in chromosomes 4

5

15 and 16 and 5~50 kb upstream region of transcription start sites showed statistically significant differences.       Conclusion       This study reveals an integration pattern that lentiviral vector preferentially integrates into the vicinity of transcription start sites with no favor for genes in the genome of human keratinocytes

and provides experimental evidences for assessing the latent risk of lentiviral vector used in gene therapy for skin diseases.