Polymer-encapsulated PC12 cells promote recovery of motor function in aged rats

The feasibility of using polymer-encapsulated PC12 cells to ameliorate the motor deficits in aged rats was evaluated. Spontaneous locomotion and motor coordination was evaluated in young (5-6 month) and aged (24-25 month) rats. Aged animals tested for spontaneous locomotor activity in Digiscan animal activity monitors were found to be hypoactive relative to young animals. Compared to the young animals the aged animals: (1) remained suspended from a horizontal wire for less time, (2) were unable to descend a wooden pole covered with wire mesh in a coordinated manner, (3) fell more rapidly from a rotating rod, and (4) were unable to maintain their balance on a series of wooden beams with either a square or rounded top of varying widths. Prior to implantation PC12 cell-loaded capsules were chromatographically characterized for catecholamine release. Following baseline testing, aged animals received either no implant, empty capsules, or PC12 cell-loaded capsules implanted bilaterally into the striatum. Three weeks following surgery, animals were retested and a significant improvement in balance on the rotorod and wooden beams was observed in those aged animals receiving PC12 cell-loaded capsules. No recovery was observed in the animals receiving PC12 cell-loaded capsules on any of the other motor tasks. Likewise, no improvement was observed on any behavioral measure in those animals receiving empty capsules. Histological analysis revealed the presence of numerous surviving tyrosine hydroxylase-positive PC12 cells within the capsules. Encapsulated PC12 cells survive following implantation into aged rats and such a technique may be useful for treating some of the behavioral consequences of aging.