Fetal porcine ventral mesencephalon graft. Determination of the optimal gestational age for implantation in parkinsonian patients.

Human fetal ventral mesencephalon tissue has been used as dopaminergic striatal implants in Parkinsonian patients, so far with variable effects. Fetuses from animals that breed in large litters, e.g., pigs, have been considered as alternative donors of dopaminergic tissue. The optimal gestational age of the porcine fetal donors has not been studied systematically. We collected ventral mesencephalic (VM) tissue from fetal pigs, embryonal ages E21, E28, E42, and E70, and examined the viability of the fetal VM cells after dissociation, the expression of tyrosine hydroxylase (TH) in culture, the presence of catecholamines, and the cellular survival and outgrowth up to 10 months after intrastriatal implantation in rats. The highest viability was found in suspensions prepared from E28 fetuses. The highest number of TH-positive cells was found in cell cultures prepared from E28 VM tissue. Explants with a gestational age of 28 and 42 days contained the largest amount of dopamine. Only E28-derived grafts showed TH-cell survival after implantation in rat striatum. Our results show that a gestational age of 28 days must be considered to be the optimal age for dopaminergic tissue derived from pig fetuses for therapeutic use as intrastriatal grafts in Parkinsonian patients.

Ontogenesis of embryonic porcine ventral mesencephalon in the perspective of its potential use as a xenograft in Parkinson's disease.

Human fetal neural dopaminergic tissue can be transplanted and can ameliorate neurological deficiencies in patients with Parkinson's disease (PD). Donor tissue from other species has been used experimentally for several years in animal experiments and is now being considered an attractive alternative, particularly from a donor species that breeds in large litters, e.g., the pig. We have studied the early ontogenetic development of the mesencephalic dopaminergic system in the pig, utilising an anti-tyrosine hydroxylase (TH) immunocytochemical technique, and demonstrated the earliest appearance of its cell bodies at embryonic day 20 (E20). We compared the porcine data with those of human fetal development, as revealed by the same technique. Embryonic dopaminergic cell groups resembling the A8, A9, and A10 of the rat are present in the pig and differentiate into the homologous cell groups of human, although interesting quantitative differences are apparent. In the pig, prolonged presence of immature characteristics of TH-immunoreactive (TH-i.r.) cell bodies was observed, notwithstanding the early outgrowth of TH-i.r. axons into the ganglionic eminence. In the human, on the other hand, cell divisions and maturation of dendrites have progressed to a further degree than in the pig, before such distinct outgrowth of axons takes place. In pig embryos of 28 days, cells in the ventral mesencephalon had differentiated into TH containing neurons, which indicates their potential to synthesize dopamine. In spite of their differentiation, these cells still showed immature morphological features (rounded cell bodies with undifferentiated, short processes). Dopamine synthesis by these cells was demonstrated in previous studies by the high performance liquid chromatographic technique (HogenEsch et al. [1993] Can. J. Neurol. Sci. 20(suppl. 4):P.S. 235). In a separate paper, we have described that these porcine 28-day dopaminergic cells retain their potential for development and outgrowth in culture (van Roon et al. [1995] Res. Neurol. Neurosci. 7:199-205). We conclude that the ventral mesencephalon in pig embryos of 28 days is a potential source of dopaminergic neurons to be used as a xenograft in PD.

Fetal porcine ventral mesencephalon grafts: dissection procedure and cellular characterization in culture.

The objective of this study was to develop an optimal dissection procedure for fetal porcine ventral mesencephalon (VM) grafts and to characterize the cellular composition of such an explant, in particular with respect to the dopaminergic and GABAergic components. We have used a monolayer cell culture system to study and identify the various VM cell types. The in vitro development of the fetal VM cells and the effect of the addition of brain-derived neurotrophic factor (BDNF) was investigated during a culture period of 5 days. Extracellular dopamine levels were measured by means of high performance liquid chromatography (HPLC) with electrochemical detection (LCEC). Our results indicate that the ratio of dopaminergic to GABAergic neurons changed in favour of the dopaminergic component when a more selective dissection technique was used. Although addition of BDNF to the cultures appeared to exert trophic influences on all the cellular components of pig fetal VM, this effect was most pronounced on the TH-positive cells. Highest extracellular DA levels were found in the VM culture with the addition of BDNF and when a more selective dissection method was used. Our in vitro findings suggest that porcine fetal dopaminergic cells retain their potential for development and outgrowth after proper explantation and dissociation. Anticipating on the results of ongoing transplantation studies in rat, they suggest that pig fetal VM can be a suitable alternative for the use of fetal human VM as a graft for Parkinson's disease.

Utility of fragmented human fetal tissue as a potential dopaminergic brain graft in Parkinson's disease.

There is increasing interest in the use of human fetal dopaminergic tissue as a source of striatal transplant in parkinsonian patients. This tissue is acquired by elective abortions. The possibilities of the use of this tissue were studied by macroscopical examination, cell-culturing followed by immunohistochemical staining and by high performance liquid chromatography. It turned out that 50% of the curettages obtained by suction abortion were too fragmented to reliably recognize the dopamine-containing area (ventral mesencephalon). Furthermore, dissection of the brainstem immediately after the abortion procedure seemed to be of utmost importance.

Tumors of the cauda equina: the importance of an early diagnosis.

The natural history of cauda equina tumors was studied in 13 patients. Pain was the most prominent clinical manifestation. Neurological dysfunction mainly consisted of sensory disturbances. The pre-operative course was in 62% three years or longer. A relation was found between the histology of the tumor and the delay of diagnosis: ependymomas were discovered much later than schwannomas. Other histological types of tumors were meningioma, sarcoma and metastasis of a medulloblastoma. The effect of treatment, in nine cases only surgical, was excellent in seven of the 13 patients. The prognosis was determined by histology and length of pre-operative period.

Sympathetic dysfunction in patients with persistent pain after prolapsed disc surgery. A thermographic study.

Vasomotor function in the lower limbs was tested by means of thermography in 48 patients with and without residual complaints after surgery for a prolapsed intervertebral disc. There is a definite correlation between the severity of the complaints and the thermographic responses which corresponds well with the evidence for a sympathetic reflex dystrophy of the legs (causalgia).