The Origin of a New Progenitor Stem Cell Group in Human Development.

The observation of two precursor groups of the early stem cells (Groups I and II) leads to the realization that a first amount of fetal stem cells (Group I) migrate from the AMG (Aortal-Mesonephric-Gonadal)-region into the aorta and its branching vessels. A second group (Group II) gains quite a new significance during human development. This group presents a specific developmental step which is found only in the human. This continuation of the early development along a different way indicates a general alteration of the stem cell biology. This changed process in the stem cell scene dominates the further development of the human stem cells. It remains unclear where this phylogenetic step first appears. By far not all advanced mammals show this second group of stem cells and their axonal migration. Essentially only primates seem to be involved in this special development.

Grafts of extra-adrenal chromaffin cells as aggregates show better survival rate and regenerative effects on parkinsonian rats than dispersed cell grafts.

The objective was to discern the neuroregenerative effect of grafts of extra-adrenal cells of the Zuckerkandl's paraganglion (ZP) in the nigrostriatal circuit, by using the retrograde model of parkinsonism in rats. The antiparkinsonian efficacy of two types of grafting procedures was studied (cell aggregates vs. dispersed cells), and GDNF and TGFbeta(1) (dopaminotrophic factors) as well as dopamine presence in extra-adrenal tissue was analyzed. Extra-adrenal chromaffin cells are noradrenergics, tissue dopamine is low, and they express both GDNF and TGFbeta(1). Grafts of cell aggregates, not of dispersed cells, exerted a trophic regeneration of the host striatum, leading to amelioration of motor deficits. Sprouting of spared dopaminergic fibers within the striatum, reduction of dopamine axon degeneration, and/or enhanced phenotypic expression of TH would explain striatal regeneration. Grafted cells as aggregates showed a better survival rate than dispersed cells, and they express higher levels of GDNF. Higher survivability and GDNF content together with the neurorestorative and dopaminotrophic action of both GDNF and TGFbeta(1) could account for striatal recovery and functional amelioration after grafting ZP cell aggregates. Finally, nigral degeneration and partial degeneration of ventral tegmental area were not precluded after transplantation, indicating that the trophic effect of grafts was local within the host striatum.

Searching for an intrinsic neuroendocrine cell in the kidney. An immunohistochemical study of the fetal, infantile and adult kidney.

The pathogenesis of primary renal carcinoid tumor is unknown. One hypothesis has implied derivation from a yet unrecognized intrinsic neuroendocrine cell in the renal parenchyma/hilum either as a minute endocrineparacrine constituent or resulting from entrapped/misplaced progenitor cells of the so-called dispersed neuroendocrine system during organogenesis. Immunohistochemical staining for chromogranin and serotonin was systematically performed on a whole-mount and geographically mapped normal adult kidney, kidneys from 15 fetuses (age range: 15 to 38 weeks), and renal specimens from 18 infants/children (age range: 7 days to 123 months). Minute paraganglion nests (composed of chromogranin positive/serotonin negative chief cells and S-100 protein positive dendritic cells) were incidentally detected within the renal hilum primitive stroma (unilaterally) of two fetuses at 22 and 26 weeks. Sequestration and persistence of such paraganglion nests during renal growth and maturation would offer a basis for the rare occurrence of extra-adrenal paraganglioma involving the renal hilum/pedicle. Otherwise, no neuroendocrine cell was detected within the renal parenchyma or hilum, therefore not validating/sustaining the aforementioned hypothesis in the pathogenesis of renal carcinoid tumor.

Immunochemical localization of chromaffin cells during the embryogenic migration.

Adrenal medulla together with the sympathetic nervous system constitute an anatomo functional unit. Both tissues derive from precursor cells which originate from the neural crest and later differentiate during migration into sympathetic neurons or chromaffin cells. Biosynthesis enzymes of catecholamines such as DBH (dopamine beta hydroxylase) and PNMT (phenylethanol amine-N-methyl transferase) as well as the neurotransmitter serotonin , can be detected by immunohistochemical techniques from 15 to 20 prenatal days. Cells migrating along the dorsal aorta could be observed at 15 prenatal days. From day 16 on, three distinct cellular groups could be distinguished according to the intensity of the immunoreactivity: chromaffin, paraganglion and sympathetic ganglion cells. From day 18, chromaffin cells immunostained as DBH' PNMT+ or DBH+ PNMT could be detected differentiating into what would be adrenergic or noradrenergic cells, respectively Progenitor cells migrating from the neural crest to the adrenal cortical blastema reach a micro-environment where glucocorticoids could possibly influence gene expression for PNMT in some of these undifferentiated cells, causing adrenaline synthesis. Serotonin(5HT) immunoreactivity is localized from 17 prenatal days in several groups of the paraganglionic cells where they could be a modulator for chromaffin differentiation.

[Histological study of the paracervical ganglion (Frankenhäuser) in mice (author's transl)].

The paracervical ganglion in dd-mice ranging in age from birth to 90 days was studied qualitatively and quantitatively by light microscopy. The paracervical ganglion is located just lateral to the fornix vaginae, and is shaped like a flattened cone. Out of the parenchymal cells, nerve cells are 97% and chromaffin cells are 3%, respectively. The chromaffin cells are arranged in small clusters or individually, and are scattered throughout the ganglion. Their chromaffin reaction varies in density from cell to cell. In neonatal mice, the ganglion consists of nerve cells and small spherical cells. With advancing age, as the small cells decrease in number, chromaffin cells appear. At 20 days of age, the ganglion is almost similar in structure to that of the adult. The nuclear and cellular size distribution curves of nerve cells are symmetrical in pattern after the age of 20 days. The nuclear size distribution curves of the chromaffin cells are symmetrical and are almost the same in pattern in newborns as in adults. The cellular size distribution curve of chromaffin cells are symmetrical before 20 days of age, but, with advancing age, the curve shifts to the larger size and becomes asymmetrical in pattern due to an increase of larger cells.

Zuckerkandl's organ improves long-term survival and function of neural stem cell derived dopaminergic neurons in Parkinsonian rats.

Transplantation of neural stem cells (NSC) derived dopamine (DA) neurons has emerged as an alternative approach to fetal neural cell transplantation in Parkinson's disease (PD). However, similar to fetal neural cell, survival of these neurons following transplantation is also limited due to limited striatal reinnervation (graft with dense neuronal core), limited host-graft interaction, poor axonal outgrowth, lack of continuous neurotrophic factors supply and principally an absence of cell adhesion molecules mediated appropriate developmental cues. In the present study, an attempt has been made to increase survival and function of NSC derived DA neurons, by co-grafting with Zuckerkandl's organ (a paraneural organ that expresses neurotrophic factors as well as cell adhesion molecules); to provide continuous NTF support and developmental cues to transplanted DA neurons in the rat model of PD. 24 weeks post transplantation, a significant number of surviving functional NSC derived DA neurons were observed in the co-transplanted group as evident by an increase in the number of tyrosine hydroxylase immunoreactive (TH-IR) neurons, TH-IR fiber density, TH-mRNA expression and TH-protein level at the transplantation site (striatum). Significant behavioral recovery (amphetamine induced stereotypy and locomotor activity) and neurochemical recovery (DA-D2 receptor binding and DA and DOPAC levels at the transplant site) were also observed in the NSC+ZKO co-transplanted group as compared to the NSC or ZKO alone transplanted group. In vivo results were further substantiated by in vitro studies, which suggest that ZKO increases the NSC derived DA neuronal survival, differentiation, DA release and neurite outgrowth as well as protects against 6-OHDA toxicity in co-culture condition. The present study suggests that long-term and continuous NTF support provided by ZKO to the transplanted NSC derived DA neurons, helped in their better survival, axonal arborization and integration with host cells, leading to long-term functional restoration in the rat model of PD.

A study of the distribution of chromaffin-positive (CH+) and small intensely fluorescent (SIF) cells in sympathetic ganglia of the rat at various ages.

Small intensely fluorescent (SIF) and chromaffin-positive (CH+) cells were independently investigated by formol-induced fluorescence and by chromaffin techniques in the superior cervical, thoracic and coeliac-mesenteric ganglia of neonatal (2--10 days), adolescent (2--4 months) and adult (6--15 months) rats. Identification of CH+ cells was facilitated by glutaraldehyde fixation prior to chromatin. Intraganglionic blood vessels were displaced by antemortem injection of either India ink or the fluorescent dye Thioflavine-S. SIF and CH+ cells were randomly distributed through the ganglia, either singly or in pairs related to principal neurons, or in variably-sized, highly vascularized groups. In chromaffin preparations these groups either consisted entirely of CH+ cells or else they contained a mixture of CH+ and CH- cells. CH+ cells were present in some adolescent and adult ganglia of all types, and in the neonatal coeliac-mesenteric ganglion at 10 days. In neonatal material generally, SIF cells were mostly green fluorescent, occurring separately or in homogeneous or mixed groups, but both yellow and green cells occurred in coeliac-mesenteric ganglia at 10 days. All ganglia in adolescent and older animals contained both yellow and green cells. There were more green than yellow cells, and more SIF than CH+ cells in all ganglia studied.

The paraganglia, a persisting endocrine system in man.

The paraganglia have been traced in surgical samples of para-aortic and pelvic retroperitoneal tissues using the formal-dehyde-induced fluorescence method for catecholamines. Clusters of catecholamine-storing cells were found in all (12) patients studied. Microspectrofluorometric recordings showed high amounts of catecholamine in the well-vascularized cell groups. A large proportion of the paraganglia, which are most prominent during the fetal period, also persist during postnatal life.

An immunohistochemical study of human postnatal paraganglia associated with the urinary bladder.

Histological and immunohistochemical methods were used to study pelvic paraganglia in a series of human postnatal specimens ranging in age from 1 month to 6 y. Up to 5 months of age, many of the encapsulated paraganglia contained small pacinian-like sensory corpuscles which occurred either singly or in small clusters, implying an unknown functional interrelationship during this period. In older specimens, this intimate association was not observed since pacinian corpuscles and small nonencapsulated clusters of paraganglion cells were observed only as separate structures. It is suggested that the paraganglion cells may induce the formation of the pacinian corpuscles during fetal development. Immunohistochemistry using the nerve marker protein gene product (PGP 9.5) demonstrated a rich plexus of varicose nerve fibres within the paraganglia which may directly innervate the paraganglion cells and/or be associated with the profuse vascular supply. A similar density of vasoactive intestinal polypeptide-containing nerves was also demonstrated while some of the nerves contained calcitonin gene related peptide or substance P. The paraganglion cells stained positively for tyrosine hydroxylase, dopamine-beta-hydroxylase and neuropeptide Y, but not for phenylethanolamine N-methyltransferase. This combination of immunostaining confirms them as a rich source of noradrenaline.

Catecholamines in paraganglionic cells of the rat superior cervical ganglion: functional aspects.

In the rat SCG two types of paraganglionic cells have been identified immunohistochemically in a ratio of about 5% DBH-positive to 95% DBH-negative cells. Measurements of CAs in SIF cell clusters separated from principal neurons with the microlaser and using the technique of quantitative mass fragmentography disclosed the presence of E within paraganglionic cells, thus confirming the proposal that, besides DA, E also is stored in most cells. Following immobilization of adult rats, the majority of SIF cells revealed a time-dependent loss of formaldehyde-induced fluorescence intensity that could be ultrastructurally correlated with an increasing degranulation of small granule-containing perikarya, presumed to store DA and E. Similar results were obtained in type I cells of the rat carotid body and adrenal medullary cells, thus suggesting a mutual endocrine function. An additional interneuronal mode of modulation is assumed, since degranulated cells are capable of displaying efferent synaptic contact with postganglionic neurons. A minor cell population, storing granular vesicles similar to those in the NE-containing cells of the adrenal medulla, did not respond with degranulation to functional strain of the vegetative nervous system. Our results strongly corroborate the hypothesis that a functional dualism exists: Most paraganglionic cells can act as an interneuron and as an endocrine cell.

Abdominal vagal paraganglia: distribution and comparison with carotid body, in the rat.

A study was made of the distribution of abdominal vagal paraganglia in the gastro-oesophageal region of 12 rats. In all rats 4-40 paraganglia were found embedded in, or closely associated with, the vagus nerves and their branches. The paraganglia consisted of groups of rounded, weakly chromaffin-positive cells surrounded by flattened cells and supplied by small nerves and blood vessels. The paraganglia were morphologically identical to simultaneously fixed carotid body tissue and showed similar fluorescence characteristics.

Normal paraganglia in the human prostate.

A normal paraganglion was discovered incidentally in prostatic fragments resected for nodular prostatic hyperplasia.

Monoamine-storing cells in the avian aortic wall.

Using the Falck-Hillarp method, monoamine-storing cells were demonstrated in the avian thoracic aorta just above the openings of the ductus arteriosus. By electron microscopy, numerous dense-cored vesicles, 90-220 nm in diameter, were seen in the cytoplasm. The electron opacity of these dense-cored vesicles was reduced when reserpine (5 mg/kg) was administered. These monoamine-storing cells formed typical synapses with the Schwann cell-enclosed nerve terminals. The monoamine-storing cells first appeared in the aortic wall at 9 days in ovo but it remained obscure whether they originated from the neuroectoderm.

[Stem cells: solution to the problem of transplants in Parkinson's disease?]. / Células madre: ¿solución a la problemática actual de los trasplantes en la enfermedad de Parkinson?

The use of neural transplantation or cellular therapies for Parkinson's disease (PD) is based on the idea of substituting nigral dopaminergic neurons lost as a consequence of the degenerative process. More than 400 people with PD have received a transplant with highly variable results. Success of cellular therapy depends on the survival of a sufficient number of trasplanted dopaminergic cells and on the restoration of normal striatal circuitry, disrupted by the disease process. None of the currently used cellular sources can generate an unlimited number of dopaminergic cells. Stem cells (SC) are pluripotent cells which may be obtained from embryonic, fetal or adult tissues. SC can be isolated, expanded in culture during long periods of time and induced to differentiate into dopaminergic cells. Cellular lines can be created and can be stored. Therefore, a large amount of dopaminergic cells can be obtained from a single SC and they can be used when necessary. Embryonic SC seems to be more plastic than adult SC; however, the plasticity of adult SC may be higher than initially thought due to a phenomenon called transdifferentiation. Several studies carried out in experimental models have shown that SC therapy is viable. SC may be also the ideal vehicle for gene therapy. However, much work remains to be done before SC can be applied to human beings. Different aspects of neural development should be elucidated and important practical problems should be overcome, particularly those related to the development of germinal tumors and immunological rejection. Finally, ethical controversies should be carefully managed. Neurología 2003;18(2):74-100

Effects of 5-hydroxydopamine and 6-hydroxydopamine on the ultrastructure of type I cells in paraganglia of the rat recurrent laryngeal nerve.

The ultrastructure of the Type I cells in paraganglia of rat recurrent laryngeal nerve (RLN) was studied after the administration of 5-hydroxydopamine (5-OHDA) and 6-hydroxydopamine (6-OHDA). Normal Type I cells of RLN-paraganglia contained abundant organelles and their cytoplasm was characterized by the presence of numerous membrane-bounded dense-cored vesicles (DCVs). The DCVs were round in profile (diameter 107.67 +/- 0.06 nm, all values expressed as mean +/- s.e.m. in the present study) and possessed dense cores of moderate to low electron density. After 5-OHDA treatment (single injection, 100 mg/kg b.w., i.v.), the majority of DCVs were filled with a material of high electron density. No significant difference was observed between the profile diameter of the DCVs in 5-OHDA-treated rats (104.96 +/- 0.06 nm) and that in normal rats. After 6-OHDA treatment (three injections, 100 mg/kg b.w. each at 12 h intervals i.p.), no significant alteration in the electron density of the core was noted. However, most of the DCVs were enlarged and round, elliptical or irregular in profile (190.57 +/- 2.77 nm x 130.34 +/- 2.09 nm). The dense core of DCVs was centrally or eccentrically located in DCVs. The results of the present study indicate that: 1) there is only one type of granulated glomus cell (i.e., Type I cells) in the rat RLN-paraganglia under normal physiological condition; and 2) since the ultrastructural morphology of DCVs in Type I cells of rat RLN-paraganglia is altered after 5-OHDA or 6-OHDA treatment, these cells may possess mechanisms for the uptake of false adrenergic neurotransmitter and/or neurotoxin.

Hypoxia alters gene expression in human neuroblastoma cells toward an immature and neural crest-like phenotype.

Insufficient oxygen and nutrient supply often restrain solid tumor growth, and the hypoxia-inducible factors (HIF) 1 alpha and HIF-2 alpha are key transcription regulators of phenotypic adaptation to low oxygen levels. Moreover, mouse gene disruption studies have implicated HIF-2 alpha in embryonic regulation of tyrosine hydroxylase, a hallmark gene of the sympathetic nervous system. Neuroblastoma tumors originate from immature sympathetic cells, and therefore we investigated the effect of hypoxia on the differentiation status of human neuroblastoma cells. Hypoxia stabilized HIF-1 alpha and HIF-2 alpha proteins and activated the expression of known hypoxia-induced genes, such as vascular endothelial growth factor and tyrosine hydroxylase. These changes in gene expression also occurred in hypoxic regions of experimental neuroblastoma xenografts grown in mice. In contrast, hypoxia decreased the expression of several neuronal/neuroendocrine marker genes but induced genes expressed in neural crest sympathetic progenitors, for instance c-kit and Notch-1. Thus, hypoxia apparently causes dedifferentiation both in vitro and in vivo. These findings suggest a novel mechanism for selection of highly malignant tumor cells with stem-cell characteristics.