Hormone-responsive cells derived from human dental papilla: Characterization in vitro and in vivo in diffusion chambers

Summary Cells of the dental papilla are capable of odontoblastic, fibroblastic, and endothelial differentiation and formation of dentin and the dental pulp. In the present study dental papilla cells, obtained from human tooth buds (HDP cells), were cultured in vitro through 3 to 7 passages. After exposure to prostaglandin E₂ there was a marked decrease in intracellular cyclic AMP (cAMP) levels as compared to hormone-free controls. Parathyroid hormone and calcitonin had stimulatory effects with 1 and 2 log increases in cAMP, respectively. The HDP cells showed moderate activity of alkaline phosphatase, 1 log higher than that of hamster kidney fibroblasts (BHK 13) and 1 log lower than that of osteoblastic osteosarcoma cells (ROS 17/2). When cultured for 4 or 8 wk in diffusion chambers (DC) implanted in athymic mice, many of the HDP cells underwent odontoblastic morphodifferentiation with very long, single processes extending into the matrix. This matrix contained banded and unbanded collagen fibers. Neither light nor electron microscopy of the DC content revealed mineral deposits. These results suggest that HDP cells have an intrinsic potential for partial odontoblastic differentiation; inductive signals like those originating from odontogenic epithelium are probably essential for the completion of hard tissue formation.     

Vascular endothelial cells: Targets for studying the activity of hair follicle cell-produced VEGF

Fetal bovine aortic endothelial cells (FBAEC) were exposed to purified fractions of conditioned medium from cultures of hair dermal papilla cells (DPC) to determine the existence of any vascular endothelial growth factor (VEGF)-like paracrine activity of the latter. Such fractions were tested for stimulation of growth and migration of cultured FBAEC. In addition, VEGF secretion by DPC was measured by radioassay of VEGF receptors using FBAEC as target cells. The results showed that stimulation of FBAEC proliferation and migration following exposure to purified conditioned medium was dose-dependent. Radioreceptor assays of recombinant VEGF and purified DPC-conditioned medium showed competitive VEGF binding in FBAEC.Abbreviations CM conditioned medium - DMEM Dulbecco's modified eagle's medium - DPC dermal papilla cells - EDTA ethylenediaminetetra-acetic acid - FBAEC fetal bovine aortic endothelial cells - FCS fetal calf serum - VEGF vascular endothelial growth factor     

大鼠肾髓质活体微循环及观察方法

采用肾乳头暴露方法活体观察Sprague-Dawley大鼠肾髓质微循环。结果发现:正常成年大鼠肾乳头可暴露1.1±0.5mm; 乳头表面直血管数29.8±6.3;升、降支比例3.4:1。升支平均直径13.68±6.13μm,降支10.8±2.57μm。肾乳头连续暴露观察10h,其微循环未发生明显病理性改变。说明这一方法可以用于肾髓质微循环活体研究。     

The structure of the rectal papilla in a parasitoid hymenopteran Nasonia vitripennis (Walker) (Hymenoptera Pteromalidae)

Summary The ultrastructure of the rectal papillae of the parasitoid hymenopteran, Nasonia vitripennis (Walk), is described. These organs in this insect consist of four distinct cell types arranged as a closed, hollow cone. The majority of the cells are present in the raised cone, and are characterised by large numbers of mitochondria arranged in a membranous labyrinth. A series of cells form a collar around the base of the cone. Junction cells have been identified which are present at the point of insertion of the cone into the rectal epithelium. The base of the cone consists of cells with elaborately folded plasma membranes facing both the central cavity of the cone, and the haemolymph. The structure of this rectal papilla is compared with those found in other insects.We are indebted to Professor E. W. Knight-Jones in whose department the work was carried out, and to the Science Research Council for support for one of us (I.D.).     

Multiple Shh signaling centers participate in fungiform papilla and taste bud formation and maintenance

The adult fungiform taste papilla is a complex of specialized cell types residing in the stratified squamous tongue epithelium. This unique sensory organ includes taste buds, papilla epithelium and lateral walls that extend into underlying connective tissue to surround a core of lamina propria cells. Fungiform papillae must contain long-lived, sustaining or stem cells and short-lived, maintaining or transit amplifying cells that support the papilla and specialized taste buds. Shh signaling has established roles in supporting fungiform induction, development and patterning. However, for a full understanding of how Shh transduced signals act in tongue, papilla and taste bud formation and maintenance, it is necessary to know where and when the Shh ligand and pathway components are positioned. We used immunostaining, in situ hybridization and mouse reporter strains for Shh, Ptch1, Gli1 and Gli2-expression and proliferation markers to identify cells that participate in hedgehog signaling. Whereas there is a progressive restriction in location of Shh ligand-expressing cells, from placode and apical papilla cells to taste bud cells only, a surrounding population of Ptch1 and Gli1 responding cells is maintained in signaling centers throughout papilla and taste bud development and differentiation. The Shh signaling targets are in regions of active cell proliferation. Using genetic-inducible lineage tracing for Gli1-expression, we found that Shh-responding cells contribute not only to maintenance of filiform and fungiform papillae, but also to taste buds. A requirement for normal Shh signaling in fungiform papilla, taste bud and filiform papilla maintenance was shown by Gli2 constitutive activation. We identified proliferation niches where Shh signaling is active and suggest that epithelial and mesenchymal compartments harbor potential stem and/or progenitor cell zones. In all, we report a set of hedgehog signaling centers that regulate development and maintenance of taste organs, the fungiform papilla and taste bud, and surrounding lingual cells. Shh signaling has roles in forming and maintaining fungiform papillae and taste buds, most likely via stage-specific autocrine and/or paracrine mechanisms, and by engaging epithelial/mesenchymal interactions.     

Histochemical Studies of the Non‐Host Resistance and the Role of Actin Cytoskeleton in Pepper Against Colletotrichum orbiculare

The penetration process and defence reactions (hypersensitive response, oxidative burst and cell wall fortification) of Colletotrichum orbiculare were studied histochemically on pepper cultivar ‘A11’ (non‐host) and susceptible cucumber cultivar ‘Changchun Thorn’ (host). The results indicate that C. orbiculare could hardly penetrate the non‐host pepper leaves. It was papillae rather than hypersensitive response and H₂O₂ that played an important role in resisting the colonization and development of C. orbiculare on the non‐host pepper. The depolymerization of the actin microfilament weakened the papilla deposition of pepper and allowed successful penetration of the non‐adapted C. orbiculare, suggesting that the actin cytoskeleton of pepper is significant in preventing the invasion of the non‐host pathogen C. orbiculare.     

Adhesive papillae on the brachiolar arms of brachiolaria larvae in two starfishes, Asterina pectinifera and Asterias amurensis, are sensors for metamorphic inducing factor(s)

It has been hypothesized by Barker that starfish brachiolaria larvae initiate metamorphosis by sensing of metamorphic inducing factor(s) with neural cells within the adhesive papillae on their brachiolar arms. We present evidence supporting Barker's hypothesis using brachiolaria larvae of the two species, Asterina pectinifera and Asterias amurensis. Brachiolaria larvae of these two species underwent metamorphosis in response to pebbles from aquaria in which adults were kept. Time-lapse analysis of A. pectinifera indicated that the pebbles were explored with adhesive papillae prior to establishment of a stable attachment for metamorphosis. Microsurgical dissections, which removed adhesive papillae, resulted in failure of the brachiolaria larvae to respond to the pebbles, but other organs such as the lateral ganglia, the oral ganglion, the adhesive disk or the adult rudiment were not required. Immunohistochemical analysis with a neuron-specific monoclonal antibody and transmission electron microscopy revealed that the adhesive papillae contained neural cells that project their processes towards the external surface of the adhesive papillae and they therefore qualify as sensory neural cells.     

Cultured human and rat tooth papilla cells induce hair follicle regeneration and fiber growth

The mesenchymal-epithelial interactions that characterize the early stages of tooth and hair follicle morphogenesis share certain similarities, and there is increasing evidence that mesenchymal cells derived from both mature structures retain interactive and stem cell-like properties. This study aimed to gauge the cross-appendage inductive capabilities of cultured tooth dental papilla (or pulp) cells from different species and ages of donor. Adult human and juvenile rat tooth papilla cells were implanted into surgically inactivated hair follicles within two different microenvironments. The human cells interacted with follicle epithelium to regenerate new end bulbs and create multiple differentiated hair fibers. Rodent tooth dental cells also induced new epithelial matrix structures and stimulated de novo hair formation. However, in many instances they also elicited mineralization and bone formation, a phenomenon that appeared to relate to their donor's age; the type of tooth of origin; and the host environment. Taken together, this study reveals that cultured dental papilla cells from postnatal mammals (adult, juvenile, and newborn) retain inductive molecular signals that must be common to both hair and teeth follicles. It highlights the stem cell-like qualities and morphogenetic abilities of tooth and hair follicle cells from mature humans, and their capacity for cross-appendage and interspecies communication and interaction. Besides the developmental implications, the present findings have relevance for stem cell biology, hair growth, tissue repair, and other biotechnologies. Moreover, the critical importance of considering the local microenvironment in which different cells/tissues are naturally or experimentally engineered is firmly demonstrated.