Quantitative [¹⁸F]Fluorodopa/PET and Histology of Fetal Mesencephalic Dopaminergic Grafts to the Striatum of MPTP-Poisoned Minipigs

Abstract

The functional restoration of the dopamine innervation of striatum in MPTP-poisoned Göttingen minipigs was assessed for 6 months following grafting of fetal pig mesencephalic neurons. Pigs were assigned to a normal control group and a MPTP-poisoned group, members of which received no further treatment, or which received bilateral grafts to the striatum of tissue blocks harvested from E28 fetal pig mesencephalon with and without immunosuppressive treatment after grafting, or with additional co-grafting with immortalized rat neural cells transfected to produce GDNF. In the baseline condition, and again at 3 and 6 months postsurgery, all animals were subjected to quantitative [ 18 F]fluorodopa PET scans and testing for motor impairment. At the end of 6 months, tyrosine hydroxylase (TH)-containing neurons were counted in the grafts by stereological methods. The MPTP poisoning persistently reduced the magnitude of k 3 D , the relative activity of DOPA decarboxylase in striatum, by 60%. Grafting restored the rate of [ 18 F]fluorodopa decarboxylation to the normal range, and normalized the scores in motor function. The biochemical and functional recovery was associated with survival of approximately 100,000 TH-positive graft neurons in each hemisphere. Immunosuppression did not impart a greater recovery of [ 18 F]fluorodopa uptake, nor were the number of TH-positive graft neurons or the volumes of the grafts increased in the immunosuppressed group. Contrary to expectation, co-grafting of transfected GDNF-expressing HiB5 cells, a rat-derived neural cell line, tended to impair the survival of the grafts with the lowest values for graft volumes, TH-positive cell numbers, behavioral scores, and relative DOPA decarboxylase activity. From the results we conclude that pig ventral mesencephalic allografts can restore functional dopamine innervation in adult MPTP-lesioned minipigs.

The anatomy of the porcine subthalamic nucleus evaluated with immunohistochemistry and design-based stereology

“…The established Göttingen minipig 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model for PD (Mikkelsen et al 1999) offers several advantages as an experimental animal for brain surgery. The brain is large enough for conventional MRI and PET scanning procedures Cumming et al 2001;Watanabe et al 2001;Dall et al 2002). The minipig is affordable, compared with non-human primates, easily handled and its use potentially avoids some of the ethical considerations concerning the use of primates as laboratory animals (Goodman and Check 2002).…”

The substantia nigra pars compacta of the Göttingen minipig: an anatomical and stereological study

“…The estimate in the Østergaard study of the total neuron number in the SN of the domestic pig of 11,400-15,600 is, however, counted using the Abercrombie correction and thus not stereologically based (West et al 1991) and therefore not directly comparable with our cell count of 80,700. As noted earlier by Dall et al 2002, the Østergaard estimate is probably too low when comparing with other species. We speculate that their delineation was different than that of this study.…”

“…The Göttingen minipig has gained increased interest during the last decade as a non-primate large experimental animal, also including its use as an animal model in PD (Mikkelsen et al 1999;Danielsen et al 2000;Sørensen et al 2000;Watanabe et al 2001;Dall et al 2002;Bjarkam et al 2004Bjarkam et al , 2005Bjarkam et al , 2008aDalmose et al 2004Dalmose et al , 2005Lind et al 2007;Lindvall and Wahlberg 2008;Jensen et al 2009;Rosendal et al 2009). For further refinement and use of the animal model in PD research, detailed knowledge of the SNc is crucial.…”

“…This observation again stresses that careful attention to methods applied must be made when attempting to make direct comparisons between studies. The use of immunohistochemistry in stereological studies was first performed in the rat SN using TH (Janson and Møller 1993) and has since found wide applications (Müller et al 2001;Dall et al 2002;Hardman et al 2002;Lambertsen et al 2005;Rudow et al 2008. Although in theory simple, applying immunohistochemistry for stereological techniques requires a very good technical quality of the sections.…”

“…Its gyrated brain is large (6 9 5 9 4 cm) compared with rodents, with a great subcortical anatomical resemblance to primates (Felix et al 1999;Larsen et al 2004;Bjarkam et al 2008b;Rosendal et al 2009). The large brain enables PET and MRI scanning procedures as well as conventional neurosurgery, stereotaxic neurosurgery and surgical implantation of devices intended for human use Sørensen et al 2000;Watanabe et al 2001;Dall et al 2002;Bjarkam et al 2004Bjarkam et al , 2005Bjarkam et al , 2008aDalmose et al 2004;Lindvall and Wahlberg 2008;Jensen et al 2009;Rosendal et al 2009). The pig genome resembles that of primates (Lind et al 2007); the pig is affordable compared with primates, and many of the ethical considerations combined with using primates as experimental animals may be avoided (Goodman and Check 2002), making it possible to include more animals in studies, and thereby hopefully obtain more valid results.…”