Seeding of intravascular stents by the xenotransplantation of genetically modified endothelial cells.

A novel approach of cell seeding of stents using xenotransplanted endothelium is proposed. The advantages of this approach are that these doubly transgenic animals will provide a limitless supply of endothelial cells producing controllable levels of active compound. These foreign cells will act as Trojan horses, graciously accepted at face value by the host organism, but capable of modifying the pathophysiological response to vessel damage, typified by the process of restenosis. Once implanted, the production of the bioactive compound is under exogenous control by means of 'designer' genes coding for modified cell surface receptors, which are introduced with the transgene to provide controllable levels of compound. Interaction of an orally administered compound with the modified cell receptor will switch on the transgene, while in its absence the transgene remains dormant. We have been able to show the feasibility this type of approach has for other animal species, and it shows great potential for application to humans.

Structural relation between HDL-binding proteins in porcine liver.

We have found strong evidence for a relation between three high-density lipoprotein (HDL)-binding proteins of 90, 110, and 180 kDa in porcine liver that were detected by ligand blotting. Because HDL-binding proteins with identical molecular masses were detected in human liver, all subsequent experiments were performed with porcine liver proteins. An antiserum raised against a highly purified preparation of the 90-kDa HDL-binding protein, designated 90-PC, showed cross-immunoreactivity with the 110- and 180-kDa HDL-binding proteins. Purified protein preparations of the 90-, 110-, and 180-kDa HDL-binding proteins were obtained and analyzed by polyacrylamide gel electrophoresis with sodium dodecyl sulfate. Under nonreducing conditions these preparations showed protein bands with the expected molecular masses. Reduction of these preparations resulted in protein bands of 90 kDa. Ligand blotting experiments with 125I-HDL showed protein bands of 90, 110, and 180 kDa under nonreducing conditions and a 90-kDa protein band in all three preparations under reducing conditions. Immunoblotting experiments with 90-PC antiserum resulted in a similar pattern. The three protein preparations were then subjected to cyanogen bromide cleavage and the resulting peptides separated on gel. Immunoblotting with the 90-PC antibody revealed a pattern of protein bands that was remarkably similar in all three protein preparations. Immunohistochemical localization studies with the 90-PC antibody showed that the HDL-binding proteins were present both at the borders of the sinusoids as well as within the hepatocellular plates.(ABSTRACT TRUNCATED AT 250 WORDS)

The distribution and characterization of HNK-1 antigens in the developing avian heart.

The heart originates from splanchnic mesoderm and to a lesser extent from neural crest cells. The HNK-1 monoclonal antibody is a marker for early migrating neural crest cells, but reacts also with structures which are not derived from the neural crest. We investigated whether heart structures are HNK-1 positive before neural crest cells colonize these target tissues. To that end, we determined the HNK-1 antigen expression in the developing avian heart on immunohistochemical sections and on Western blots. The HNK-1 immunoreactivity in the developing chick heart is compared with data from literature on the localization of neural crest cells in chick/quail chimeras. Structures with neural crest contribution, including parts of the early outflow tract and the related endocardial cushions, the primordia of the semilunar valve leaflets and the aorticopulmonary septum were HNK-1 positive. Furthermore, other structures were HNK-1 positive, such as the atrioventricular cushions, the wall of the sinus venosus at stage HH 15 through 21, parts of the endocardium at E3, parts of the myocardium at E6, and the extracellular matrix in the myocardial base of the semilunar valves at E14. HNK-1 expression was particularly observed in morphologically dynamic regions such as the developing valves, the outflow tract cushion, the developing conduction system and the autonomic nervous system of the heart. We observed that atrioventricular endocardial cushions are HNK-1 positive. We conclude that: a HNK-1 immunoreactivity does not always coincide with the presence of neural crest cells or their derivatives; (2) the outflow tract cushions and atrioventricular endocardial cushions are HNK-1 positive before neural crest cells are expected (stage HH 19) to enter the endocardial cushions of the outflow tract; (3) the observed spatio-temporal HNK-1 patterns observed in the developing heart correspond with various HNK-1 antigens. Apart from a constant pattern of HNK-1 antigens during development, stage-dependent HNK-1 antigens were also found.

Regional differences between various axial segments of the avian neural crest regarding the formation of enteric ganglia.

The vagal neural crest adjacent to somites 1-7 gives rise to the enteric ganglia along the entire digestive tract. It is generally assumed that formation of enteric ganglia in preumbilical gut is independent of the axial segment from which the neural crest originates. In post-umbilical gut, however, there is evidence that the axial segment of origin of the neural crest might be relevant to neural differentiation. In this part of the gut, we previously identified a subpopulation of HNK-1-immunoreactive cells within the enteric mesenchyme. This immunoreactivity disappeared upon formation of the enteric nervous system. We studied the interaction between various axial segments of quail neural crest and the microenvironment in a neural chicken hindgut using chorioallantoic membrane cocultures. We found that neural crest cells from various axial segments could migrate into the gut and home to the correct sites. However, whereas vagal neural crest cells differentiated into enteric neurons, neural crest cells from truncal segments mainly differentiated into melanocytes. The HNK-1-immunoreactivity within the enteric mesenchyme only disappeared when neural crest cell colonization was followed by differentiation into enteric neurons and subsequent formation of enteric ganglia. To determine whether differentiation of neural crest cells in chorioallantoic membrane cocultures was influenced by the prolonged presence of the neural tube and notochord, we developed a new coculture system, using neural crest cells cultured in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Colonization characteristics of enteric neural crest cells: embryological aspects of Hirschsprung's disease.

This study explores the development of the enteric nervous system in avian embryos. Particular emphasis was given to colonization characteristics of neural crest cells present in primitive enteric ganglia. By coculturing neuronal and aneuronal gut of quail and chicken embryos, we investigated if and when neural crest cells in primitive enteric ganglia could detach from these ganglia, migrate, and colonize adjacent chicken gut. Quail neural crest cells were identified using the quail nucleolar marker and the HNK-1 antibody. Enteric neurons were identified using three monoclonal antibodies directed against neurofilament proteins. We found that neural crest cells detached from primitive ganglia in neuronal quail gut from E6 till E9, whereas neural crest cells did not leave enteric ganglia from E10 gut. These observations show that there is a transient phase during which enteric neural crest cells can leave the gut. To determine whether neural crest cells could colonize neuronal gut we cocultured neuronal gut or the neural primordium and neuronal chicken gut (E11). We found that quail neural crest cells do not colonize neuronal E11 gut, whereas they do colonize aneuronal gut of the same age. We suggest that aneuronal gut attracts neural crest cells by diffusing factors.

Characterization of HNK-1 antigens during the formation of the avian enteric nervous system.

During vertebrate embryogenesis, interaction between neural crest cells and the enteric mesenchyme gives rise to the development of the enteric nervous system. In birds, monoclonal antibody HNK-1 is a marker for neural crest cells from the entire rostrocaudal axis. In this study, we aimed to characterize the HNK-1 carrying cells and antigen(s) during the formation of the enteric nervous system in the hindgut. Immunohistological findings showed that HNK-1-positive mesenchymal cells are present in the gut prior to neural crest cell colonization. After neural crest cell colonization this cell type cannot be visualized anymore with the HNK-1 antibody. We characterized the HNK-1 antigens that are present before and after neural crest cell colonization of the hindgut. Immunoblot analysis of plasma membranes from embryonic hindgut revealed a wide array of HNK-1-carrying glycoproteins. We found that two HNK-1 antigens are present in E4 hindgut prior to neural crest cell colonization and that the expression of these antigens disappears after neural crest colonization. These two membrane glycoproteins, G-42 and G-44, have relative molecular masses of 42,000 and 44,000, respectively, and they both have isoelectric points of 5.5 under reducing conditions. We suggest that these HNK-1 antigens and the HNK-1-positive mesenchymal cells have some role in the formation of the enteric nervous system.

Regulation of chloride transport in cultured normal and cystic fibrosis keratinocytes.

Cultured normal (N) cystic fibrosis (CF) keratinocytes were evaluated for their Cl(-)-transport properties by patch-clamp-, Ussing chamber- and isotopic efflux-measurements. Special attention was paid to a 32 pS outwardly rectifying Cl- channel which has been reported to be activated upon activation of cAMP-dependent pathways in N, but not in CF cells. This depolarization-induced Cl- channel was found with a similar incidence in N and CF apical keratinocyte membranes. However, activation of this channel in excised patches by protein kinase (PK)-A or PK-C was not successful in either N or CF keratinocytes. Forskolin was not able to activate Cl- channels in N and CF cell-attached patches. The Ca(2+)-ionophore A23187 activated in cell-attached patches a linear 17 pS Cl- channel in both N and CF cells. This channel inactivated upon excision. No relationship between the cell-attached 17 pS and the excised 32 pS channel could be demonstrated. Returning to the measurement of Cl- transport at the macroscopic level, we found that a drastic rise in intracellular cAMP induced by forskolin did in N as well as CF cells not result in a change in the short-circuit current (Isc) or the fractional efflux rates of 36Cl- and 125I-. In contrast, addition of A23187 resulted in an increase of the Isc and in the isotopic anion efflux rates in N and CF cells. We conclude that Cl(-)-transport in cultured human keratinocytes can be activated by Ca2+, but not by cAMP-dependent pathways.

High density lipoprotein-binding proteins in porcine liver. Isolation and histological localization.

The antiatherogenic properties of high density lipoproteins (HDLs) are thought to reside in their involvement in the reverse cholesterol transport pathway. Specific HDL-binding proteins could play a key role in this process. Two HDL-binding proteins of approximately 90 and 180 kd were identified in porcine liver by ligand blotting and were purified to apparent homogeneity by a combination of protein extraction, DEAE-cellulose chromatography, Con A-Sepharose chromatography, and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Binding of 125I-HDL by these proteins could be actively competed for by unlabeled HDL but not by low density lipoprotein. Polyclonal antisera have been raised against these two proteins. Each antiserum recognized only one of the HDL-binding proteins, indicating that they are not immunologically related. Moreover, striking differences in localization were observed in immunohistochemical studies. The 90-kd protein is located within the hepatocellular plates, while the 180-kd protein is present along the lining of the sinusoids. These results suggest functional differences between the two HDL-binding proteins described.

Cultured epithelial cells from patients with cystic fibrosis have an increased expression of the 14 kDa Ca2(+)-binding protein CFA.

The Cystic Fibrosis antigen (CFA) is a 14 kDa. Ca2(+)-binding protein known to be expressed in cells of myeloid origin during normal cell differentiation. CFA serum levels are elevated in Cystic Fibrosis (CF) patients and heterozygotes. We examined the expression of CFA in different cultured epithelial cells from controls and patients with CF. The steady state level of CFA was in general higher in epithelial cells from CF patients compared to control cells and was found to increase during cell aging. The latter difference could be attributed to an increased rate of CFA synthesis rather than to an impairment of CFA degradation or secretion, as shown by pulse chase experiments.

Formation and malformation of the enteric nervous system in mice: an organ culture study.

Despite some progress in the treatment of congenital malformations of the enteric nervous system, there is no knowledge about the pathogenesis. The study of the normal formation of the enteric nervous system is hampered by the difficulty of manipulating and culturing mammalian embryos and their organs. Three methods to culture bowel explants of murine embryos, (chorioallantoic membrane grafting, organotypic tissue culture, and renal subcapsular space grafting) were compared. The three-dimensional cytoarchitecture of the bowel developed almost normally in the renal subcapsular space cultures. Using this culture system, it was found that neural crest cells colonize the murine bowel in distinct phases. The distal bowel was colonized at the 13th day of development. In a spontaneous mouse mutant model for intestinal aganglionosis, the lethal spotted mouse, the colonization of the distal 2 mm of the bowel did not occur at E13.

Chloride transport in cultured nasal epithelium of cystic fibrosis patients.

In this study, nasal polyp epithelial cells from control and cystic fibrosis (CF) patients were cultured using a method which allows multiple passages. The cells were tested in Ussing chamber experiments to study transcellular ion transport. Cultured CF nasal polyp cells did not exhibit spontaneous transcellular chloride transport in the presence of amiloride, in contrast to normal cells. Forskolin increased the short circuit current (Isc) in control but not CF cells. Forskolin and isoproterenol increased the cAMP levels in control and CF cells. Histamine, bradykinin and isoproterenol transiently increased the intracellular calcium level and caused a parallel increase of the transcellular chloride current in both normal and CF cells. The transient effects of isoproterenol were not sensitive to the beta blocker atenol and could not be mimicked by forskolin. We conclude that in cultured nasal polyp cells a difference in chloride transport activity between CF and control cells is retained following multiple passages. Our results suggest that the active state of chloride channels in nasal polyp cells does not require activation of a second messenger pathway. This apparently spontaneous activity appears to be reduced in CF cells. The calcium- but not the cAMP-dependent activation of transepithelial chloride secretion is at least partially preserved in cultured CF airway epithelium.

Immortalization of nasal polyp epithelial cells from cystic fibrosis patients.

We have developed immortalized epithelial cystic fibrosis (CF) cell lines by infecting cultured nasal polyp cells with a SV40/Adenol2 hybrid virus. The cell lines obtained are epithelial in nature as shown by cytokeratin production and morphology, although cytokeratins 4 and 13 typical of primary nasal polyp cells are produced at a much reduced rate. Ussing chamber experiments showed that the precrisis CF cell line NCF3 was able to perform trans-cellular chloride transport when activated by agents which elevate intracellular calcium. cAMP agonists had no effect on chloride flux in NCF3 as expected for CF cells. The apical chloride channels found with the patch clamp technique in NCF3 and in the postcrisis cell line NCF3A have a conductance similar to that of chloride channels found earlier in normal and CF epithelial cells. The channels show a delay in the onset of activity in off-cell patches and are not activated by increased cAMP levels in the cell. This indicates that immortalized CF epithelial cells will provide a useful model for the study of cystic fibrosis.

A model for aganglionosis in the chicken embryo.

We investigated the ability of neural crest (NC) cells to colonize hindgut, which had remained aneuronal due to bowel transection in ovo at an early stage. The fact that the bowel remained aneuronal proved that the "sacral" NC does not provide precursor cells for enteric neurons in the hindgut. HNK-1 immunostaining of aneuronal hindgut revealed cell-free, ganglionic structures at the site of the myenteric plexus and a sub-population of mesenchymal cells in the submucosa. We cocultured this particular type of aneuronal bowel with the vagal neural anlage of either quail or chick embryos on the chick chorioallantoic membrane. After 1 week coculture, it appeared that NC cell colonisation of the hindgut had taken place, although there was a difference between the quail-chick and chick-chick model. Quail NC cells had given rise to submucous plexuses and some myenteric plexuses. Chick NC cells had only colonised the submucous region. These findings indicate that the cell-free ganglionic structures hamper neural crest cell colonization in the myenteric region.

Diagnosis of innervation-related motility disorders of the gut and basic aspects of enteric nervous system development.

Motility disorders of the gut in children have become a matter of increasing concern for the pediatric surgeon. Infantile hypertrophic pyloric stenosis is the most common disease requiring surgery in early infancy. While this entity was first described as early as 1888 by Hirschsprung, its etiology and pathogenesis are still an enigma. Fortunately, its surgical treatment is simple and safe, which cannot be said of all other motility disorders of the infantile gut. Dysmotility in small bowel atresia and in gastroschisis is related to damaged smooth muscle cells caused by concomitant ischemia of the bowel wall. In contrast, the temporarily adynamic bowel of the prematurely born child, as well as Hirschsprung's disease and related disorders, is the result of anomalies of the intestinal innervation. The pathogenesis of congenital malformations of the enteric nervous system is still a mystery to surgeons and physicians alike. With his pressure studies of the colon, Swenson first recognized Hirschsprung's disease for what it was. This led to the resection of the manometrically diagnosed abnormal colon, which was found to be aganglionic. Histological investigation of the bowel wall became the decisive tool, replacing manometry, in the diagnosis of Hirschsprung's disease. Histochemical investigation of the bowel wall is not conclusive in other malformations of the enteric nervous system, since the presence or absence of enteric neurons is not the definitive factor discriminating between normally and abnormally functioning bowel. Monoclonal antibodies raised against neuron-specific markers may become important tools for differentiation within the spectrum of congenital malformations of the enteric nervous system. The immunocytochemical technique, however, does not provide sufficient information to explain the cause of innervation disorders of the gut in infancy and childhood. Primary migration disturbances or selective disappearance of enteric neurons following ischemia are highly unlikely to cause aganglionosis of the gut. With respect to the pathogenesis and etiology of Hirschsprung's disease, current research is focused on the embryonic bowel (target organ) in plexus formation. The enteric nervous system is still an enigma, although its origin is known, at least in birds. Why neural crest cells travel, along what paths, how they reach their destination, and what may go wrong during the migratory process, are questions that must be answered. There is increasing knowledge concerning the way in which neural crest cells aggregate and form plexuses in the gut. It is largely unknown why neural crest cells settle, in the bowel, at the sites of the myenteric and submucous plexus.(ABSTRACT TRUNCATED AT 400 WORDS)

Monoclonal antibodies in detection of choroidal melanoma.

Three monoclonal antibodies (MoAbs) prepared against cutaneous melanomas were tested against one group of 12 choroidal melanomas with indirect immunofluorescence in frozen sections. A fourth MoAb was tested in paraffin sections of a second group of 47 choroidal melanomas. One MoAb (NKI-M7) did not react with choroidal melanoma, even though it had a high sensitivity for cutaneous melanoma. A second MoAb (NKI-M6) showed a positive reaction with only 2/12 choroidal melanomas. The third MoAb (NKI/beteb) reacted with all choroidal melanomas, regardless of the cell type. MoAb NKI/C-3 was positive with 38/47 (81%) choroidal melanomas. We conclude that NKI/C-3 and NKI/beteb have a high sensitivity for both cutaneous and choroidal melanomas in frozen sections. Of these two antibodies NKI/beteb was the most specific for cutaneous naevi and melanomas.

Binding characteristics of high density lipoprotein subclasses to porcine liver, adrenal and skeletal muscle plasma membranes.

1. We compared binding characteristics of 125I-labeled high density lipoprotein (HDL) subclasses to porcine liver, adrenal and skeletal muscle plasma membranes. 2. HDL subclasses were discriminated by their buoyant densities (HDL2 and HDL3) or by their apolipoprotein (apo) content (Lp-AI (particles containing apoA-I but no apoA-II) and LpA-I/A-II (particles containing both apoA-I and apoA-II)). 3. HDL2 and HDL3 showed saturable binding to the three types of membrane preparations. 4. No differences were found in the Kds within one HDL subclass. 5. Kds and maximal binding of HDL2 were lower than these of HDL3. Unlabeled HDL2 and HDL3, but not LDL, effectively displaced 125I-HDL2 and 125I-HDL3. 6. Binding of HDL was independent of the concentration of NaCl and did not require calcium. 7. These results suggest a process mediated by a single specific receptor in porcine liver, adrenal and skeletal muscle plasma membranes. 8. We also studied binding characteristics of HDL subclasses Lp-AI and LpA-I/A-II to porcine liver membranes. LpA-I showed the highest Kd and maximal binding. 9. All types of HDL subclasses studied (i.e. HDL2, HDL3, LpA-I and LpA-I/A-II) effectively competed for binding of both Lp-AI and LpA-I/A-II, suggesting that the HDL subclasses studied bind to the same receptor by their apoA-I moiety.

Efficacy of antibody NF2F11 staining in the investigation of severe long-standing constipation. A preliminary report.

A retrospective study of 7 adult patients (6 with severe, long-standing constipation and 1 with chronic idiopathic intestinal pseudoobstruction) was carried out to test the diagnostic potential of the antineurofilament monoclonal antibody NF2F11. In 4 of the cases of constipation and in the 1 case of pseudoobstruction, paraffin sections of resected colon revealed an anomaly in that the axon bundles of both plexus systems remained unstained. This picture differed from that found in the control population. The results are discussed in relation to previous studies of congenital neurogenic abnormalities of the digestive tract in children.

The influence of the stage of differentiation of the gut on the migration of neural cells: an experimental study of Hirschsprung's disease.

Based on experimental studies in mutant mouse strains, an imbalance between the rate of migration of neural crest cells and the rate of differentiation of the mesenchyme of the distal gut has been proposed as an etiological factor in Hirschsprung's disease. We studied the influence of the stage of differentiation of embryonal chick gut on the migration of neural crest cells in an in vivo culture system: the chorioallantoic membrane. Neural crest cells in cultured gut were demonstrated with antibodies directed against the HNK-1 epitope. Enteric neurons were demonstrated with neurofilament immunoreactivity. By culturing isolated gut segments of E4 embryos, we obtained aneuronal (neurofilament-negative) embryonal chick gut up to 25 days of development. In cocultures of aneuronal gut and the neural anlage (neural tube and neural crest) neural crest cell colonization was observed, even in advanced stages of differentiation. The significance of the results is discussed in terms of the etiology of Hirschsprung's disease.

Cell division in migratory and aggregated neural crest cells in the developing gut: an experimental approach to innervation-related motility disorders of the gut.

Extensive studies in the chicken embryo have recently supplied more insights into the development of the enteric nervous system, which mainly derives from the vagal neural crest (i.e., the neural crest opposite somites 1 to 7). Crest cells migrate from this region to and via the developing gut. By means of a double labeling technique of both neural crest cells and cells in the S-phase of the cell cycle, we found that these migrating crest cells still proliferate in the gut. Some cells even go through cell division after the formation of a nerve plexus. Some implications for the pathogenesis of congenital innervation abnormalities such as hyperganglionosis and the aganglionosis of Hirschsprung's disease are discussed.

Sister chromatid exchanges, hyperdiploidy and chromosomal rearrangements studied in cells from melanoma-prone individuals belonging to families with the dysplastic nevus syndrome.

Cytogenetic investigations were performed on 25 individuals belonging to six melanoma-prone families with multiple melanocytic lesions (the dysplastic nevus syndrome, DNS). Patients having DNS with or without a history of melanoma were compared with clinically normal relatives and unrelated normal controls. The results indicate normal frequencies of hyperdiploidy and spontaneous sister chromatid exchanges in the fibroblasts of all individuals studied. Karyotypic analyses were carried out on the members of one family. The patients with DNS had a normal constitutional karyotype. In lymphocytes or fibroblasts from five patients, however, increased frequencies of cells with random chromosomal rearrangements were observed. These abnormalities, mainly translocations and inversions, were not found in two of the patients' spouses and in six clinically normal relatives. In the fibroblast cultures considerable clonal selection of cytogenetically abnormal cells occurred.