[Experimental study of dendritic cells transfected with cancer stem like cells RNA against 9L brain tumors].

Objective: To investigate the anti-tumor efficacy of dendritic cells (DC) vaccination transfected with total RNA of cancer stem like cells and to discuss the mechanism of immune response, so as to provide experimental basis for clinical application.

Methods: Dendritic cells were isolated from F344 bone marrow cells, then these dendritic cells were transfected with total RNA of 9L cancer stem cells or 9L monolayer cells. F344 rats bearing with 9L brain tumors were treated by subcutaneous injection of either PBS, unpulsed DC, DC transfected with 9L monolayer cells RNA (DC-9LTS) or DC transfected with 9L tumor spheres RNA (DC-9L)3, 10, 17. And 21 days after tumor implantation, the brains and sera were obtained from the different groups, the lymphocytes infiltration was detected by immunohistochemistry, and the concentration of interferon-γ (IFN-γ) was tested by ELISA. The survival time was observed and determined using the method of Kaplan Meier analysis.

Results: The rats vaccinated with DC transfected with 9L tumor spheres RNA (DC-9LTS) and the monolayer cell RNA (DC-9L) expired with median survival time of 36 and 31 days, respectively. The animals bearing intracranial 9L gliosarcoma were vaccinated with un-pulsed DC vaccine, all expired with a median survival time of 21 days. The Kaplan-Meier survival curve showed that the rats treated with DC-9LTS had longer survival than the other groups (P<0.01). There was significant difference among DC-9L group, DC group, and PBS group (P<0.01). There was no significant difference between DC group and PBS group (χ2=0.071, P=0.789).The concentration of IFN-gamma of DC-9LTS group [(157.08±7.25) ng/L] was much higher than those of the other groups (P<0.05). DC-9LTS could effectively enhance T-cell infiltration, a large number of CD8+ cells were detected in and around the tumor in DC-9LTS group, compared with DC-9L group, DC and PBS group (P<0.001). The expression of CD8+ cell was not detected in DC group and PBS group. However no expression of CD4+ cells was observed in all the groups.

Conclusion: Immunotherapy using DC transfected with 9L CSLCs total RNA was more effective for the treatment of 9L brain gliomas, and the strategy prolonged the survival of 9L glioma-bearing rats significantly, which provides a scientific foundation for further investigation of this approach to eradicate gliomas.