Intrastriatal Transplantation of Rat Adrenal Chromaffin Cells Seeded on Microcarrier Beads Promote Long-Term Functional Recovery in Hemiparkinsonian Rats

Possible biologic treatments for Parkinson's disease, a disorder caused by the deterioration of dopaminergic neurons bridging the nigrostriatal system, have recently focused on fetal cell transplantation. Because of ethical and tissue availability issues concerning fetal cell transplantation, alternative cell sources are being developed. The adrenal medulla has been used as a cell transplant source because of the capacity of the cells to provide catecholamines and to transform into a neuronal phenotype. However, adrenal tissue transplants have shown limited success, primarily because of their lack of long-term viability. Recently, seeding adrenal chromaffin cells on microcarrier beads has been shown to enhance the cell viability following neural transplantation. In the present study, we further investigated whether transplantation of rat adrenal chromaffin cells seeded on microcarrier beads into the striatum of 6-hydroxydopamine-induced hemiparkinsonian rats would result in a sustained functional recovery. Behavioral tests using the apomorphine-induced rotational and elevated body swing tests up to 12 months posttransplantation revealed a significant behavioral recovery in animals that received adrenal chromaffin cells seeded on microcarrier beads compared to animals that received adrenal chromaffin cells alone, medium alone, or beads alone. Histological examination of tissue at 14 months posttransplantation revealed evidence of tyrosine hydroxylase-positive cells and an on-going glial response in animals transplanted with adrenal chromaffin cells seeded on microcarrier beads, in contrast to absence of such immunoreactive responses in the other groups. These findings support a facilitator role for microcarrier beads in transplantation of adrenal chromaffin cells or other cells that are easily rejected by the CNS.