Nimodipine enhances growth and vascularization of neural grafts

The potential of the calcium channel antagonist, nimodipine, to enhance vascularization and growth of neural grafts has been investigated. Four groups of rats received unilateral 6-OHDA lesions of the nigrostriatal pathway followed 16-23 days later by intrastriatal grafts of embryonic ventral mesencephalon. The grafts were derived from (i) Embryonic Day 14 embryos (group E14), (ii) Day 17 embryos (group E17), and (iii) Day 20 embryos (group E20), all implanted within 90 min of preparation, or (iv) Day 14 embryos with a 6-h delay prior to implantation (group E14/6H). Half the rats in each group received intragastric intubation with nimodipine daily for 14 days after transplantation surgery, whereas the other half received control intubations. The rats were killed by perfusion with formalin containing Indian ink 6 weeks after grafting. Nimodipine treatment enhanced the vascularization of the grafts in all four groups and induced a significant increase in the volume of grafts under the three suboptimal transplantation conditions (i.e., groups E17, E20, E14/6H). The results suggest that vascularization of graft tissue is an important determinant of survival and growth of neural transplants prepared by the dissociated cell suspension technique and show that vascular perfusion of grafts can be enhanced by nimodipine.