Acta Pharmacologica Sinica (2009) 30: 1496–1504; doi: 10.1038/aps.2009.151

Aim:The goal of this project was to develop a rat model for neural stem cell (NSC) transplantation studies in which NSCs were modified with brain-derived neurotrophic factor (BDNF) genes that may permit extensive and reliable analysis of the transplants.

Methods: NSCs were cultured and purified by limiting dilution assay in vitro and infected with recombinant retrovirus pLXSN-BDNF (BDNF-NSCs) and retrovirus pLXSN (p-NSCs).  The expression of BDNF genes in transgenic and control NSC groups was measured by FQ-PCR and ELISA assays.  NSCs were then transplanted into the subretinal space of normal rat retinas in four groups, which included NSCs alone, BDNF-NSCs, phosphate buffered saline (PBS) control, and normal control.  Survival, migration, and differentiation of donor cells in host retinas were observed with optical coherence tomography (OCT), Heidelberg retina angiograph (HRA), and immunohistochemistry, respectively.

Results: The results obtained by FQ-PCR demonstrated that the copy numbers of BDNF gene templates from BDNF-NSCs were the highest among the four groups (P<0.05).  Consistent with the results of FQ-PCR, BDNF protein level from the supernatant of the BDNF-NSCs group was much higher than that of the other two groups (P<0.05) as suggested by the ELISA assays.  HRA and OCT showed that graft cells could successfully survive.  Immunohistochemical analysis revealed that transplanted BDNF-NSCs could migrate in the host retinas and differentiate into glial cells and neurons three months after transplantation. 

Conclusion: BDNF promotes NSCs to migrate and differentiate into neural cells in the normal host retinas.

Keywords: neural stem cells; differentiation; gene therapy; subretinal space transplantation; migration; purification