Background & objective: Murine beta defensin 2 (MBD2) is a small antimicrobial peptide of the innate immune system. It provides a critical link between the innate immune system and the adaptive immune response. This study was to develop a set of MBD2-lentivirus system, and observe its inhibitory effect on malignant ascites in mice.
Methods: MBD2 RNA was extracted from kidneys of BALB/c mice, and the fragment of MBD2 was amplified by reverse transcription-polymerase chain reaction (RT-PCR). MBD2 plasmid was constructed, and the lentivirus system expressing MBD2 was produced in 293FT cells. Mesenchymal stem cells (MSCs) were then infected with MBD2-Lentivirus, and stably infected cells (MBD2-MSCs) were selected. The expression of MBD2 was detected by RT-PCR. The biological function of MBD2 was evaluated by dendritic cell (DC) migration experiment. BALB/c mice bearing intraperitoneal MethA tumors were injected intraperitoneally with MBD2-MSCs at the 2nd, 4th, 6th, and 8th day after inoculation. Ascites status and survival status of the mice were observed. Long-term survivors were inoculated intraperitoneally with MethA tumor cells again to observe their survival status.
Results: The expression of MBD2 in MBD2-MSCs was verified by RT-PCR. Numbers of migrated DCs were significantly increased in MBD2-MSC group than in normal saline (NS) group, MSC group, and null lentivirus (Null) group (43+/-8 vs. 8+/-1, 14+/-2, and 12+/-3, P<0.01). The volume of tumor ascites was significantly less in MBD2-MSC group than in NS group, MSC group, and Null group [(3.0+/-1.0) ml vs. (10.8+/-1.0) ml, (10.2+/-1.3) ml, and (9.8+/-1.6) ml, P<0.05]. Some mice in MBD2 group were still alive 40 days after tumor inoculation, while none in control groups survived up to 20 days after tumor inoculation (P<0.05). After inoculated with MethA tumor cells again, the mice in MBD2-MSC group still survived longer than those in control groups.
Conclusion: MBD2-lentivirus gene therapy system is constructed successfully, and can inhibit the formation of malignant ascites.