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Biomedical subjects

D Gospodarowicz

Publications and source records attributed to D Gospodarowicz.

At least 181 records · Page 10Linked to original sources
PubMed1979

Transplantation of cultured bovine corneal endothelial cells to rabbit cornea: clinical implications for human studies.

Rabbit corneas denuded of their endothelium were coated with bovine corneal endothelial cells (from steers) previously maintained in tissue culture for short (20 generations) or prolonged (200 generations) periods. When grafted back into female rabbits, the corneal buttons remained clear and showed no edema. In contrast, denuded corneas coated with bovine keratocytes and grafted into rabbits became opaque and edematous within 7 days and remained so thereafter. Bovine corneal endothelial cells of the grafted corneas, which had remained clear for over 100 days, proliferated actively when put back into tissue culture. The corneal endothelial cells of the graft were characteristic of the male (XY). The chromosome number of the endothelium of the recipient rabbit was 2n = 44 with sex chromosomes characteristic of the female (XX). Results of the karyotype analysis show that there was no invasion of the corneal button by the recipient endothelium and, conversely, no invasion of the recipient endothelium by the endothelium on the corneal button. These results demonstrate that cultured corneal endothelial cells remain functional in vitro and can replace a damaged or nonfunctional endothelium in vivo.

Animals↗
PubMed1979

Appearance in confluent vascular endothelial cell monolayers of a specific cell surface protein (CSP-60) not detected in actively growing endothelial cells or in cell types growing in multiple layers.

The formation of a highly organized vascular and corneal endothelial cell monolayer is associated with the appearance of a 60,000-dalton cell surface protein (CSP-60) (30,000 daltons after reduction with dithiothreitol) which is not detectable in rapidly growing endothelial cells and in subconfluent cultures that do not yet exhibit the strict morphology of a confluent monolayer. It is also absent from vascular smooth muscle cells and from endothelial cultures that are maintained in the absence of fibroblast growth factor and grow on top of each other at confluence. After disorganization of cells in a confluent endothelial monolayer by urea, EDTA, or trypsin, CPS-60 is no longer exposed on the cell surface, but it reappears as soon as the cells readopt their characteristic two-dimensional configuration. This reorganization can be achieved in the presence of cycloheximide and despite removal of fibronectin by urea, EDTA, or trypsin. Maximal amounts of fibronectin and no CSP-60 are detected in subconfluent, but not yet organized, endothelial cultures or in endothelial cells that no longer form a monolayer of nonoverlapping cells at confluence. Likewise, cultures of vascular smooth muscle cells contain fibronectin but no CSP-60. These results suggest that CSP-60, rather than fibronectin, could be involved in the adoption of a monolayer configuration by confluent endothelial cells.

Aorta↗
PubMed1979

Vascular endothelial cells maintained in the absence of fibroblast growth factor undergo structural and functional alterations that are incompatible with their in vivo differentiated properties.

Vascular endothelial cells cultured in the presence of fibroblast growth factor (FGF) adopt at confluence a morphological appearance similar to that of the vascular endothelium in vivo. Similarly, their apical cell surface is, as in vivo, nonthrombogenic. In contrast, when the cultures are maintained in the absence of FGF, the cells undergo within two to three passages structural and functional alterations that are incompatible with their in vivo morphological appearance and physiological function. Cultures maintained in the absence of FGF no longer adopt, upon reaching confluence, the configuration of a monolayer composed of small closely apposed and nonoverlapping, cuboidal cells. Instead, confluent cultures deprived of FGF consist of large, overlapping cells which have lost the polarity of cell surface characteristic of the vascular endothelium. The apical cell surface becomes thrombogenic, as reflected by its ability to bind platelets, whereas fibronectin, which at confluence is normally associated only with the basal cell surface, can be found both on top of and underneath the cell layer. Among other changes, both sparse and confluent cultures maintained in the absence of FGF showed a greatly increased production of fibronectin. CSP-60, a cell surface protein whose appearance is correlative with the adoption of a cell monolayer configuration, can no longer be detected in cultures maintained in the absence of FGF. Overlapping endothelial cells maintained in the absence of FGF can also no longer function as a protective barrier against the uptake of ligands such as low density lipoprotein. Exposure of the culture to FGF induces a restoration of the normal endothelial characteristics concomitant with the adoption of a flattened cell monolayer morphology. These results demonstrate that, in addition to being a mitogen. FGF is involved in controlling the differentiation and phenotypic expression of the vascular endothelium. This is reflected by its effect on the morphological appearance, polarity of cell surfaces, platelet binding capacity, and barrier function of the vascular endothelium.

Animals↗
PubMed1979

Fibroblast and epidermal growth factors are mitogenic agents for cultured granulosa cells of rodent, porcine, and human origin.

The mitogenic effects of epidermal growth factor (EGF) and fibroblast growth factor (FGF) on cultured granulosa cells of different species have been analyzed. EGF and FGF are potent mitogenic agents for rabbit, porcine, and human granulosa cell cultures. While guinea pig granulosa cell cultures respond to FGF, they were hardly effected by EGF. Rat granulosa cell cultures did not respond markedly to either EGF or FGF. Our results, therefore, demonstrate that the mitogenic effects of EGF and FGF are not restricted to granulosa cells of bovine origin and, with the exception of rat granulosa cells, cultured granulosa cells responded either to FGF alone or to both EGF and FGF with a marked increase in their rates of proliferation.

Animals↗
PubMed1978

Purification of the fibroblast growth factor activity from bovine brain.

The purification of the fibroblast growth factor (FGF) from bovine brain has led to the isolation of two peptides. FGF-1 with 128 amino acids and FGF-2 with 107 amino acids. The biological activity of these two peptides is acid- and heat-labile. As indicated by the amino acid composition of FGF-1 and -2, these two peptides are derived from a common precursor and bear no resemblance to pituitary FGF. The brain FGF peptides, like pituitary FGF, are mitogenic in vitro for the same wide variety of mesoderm-derived cells. Since their mitogenic activity is acid- and heat-labile, they are thereby distinguished from the platelet factor isolated from platelets and from the cationic peptide isolated from serum which has been shown to have the same molecular weight and isoelectric point as brain and pituitary FGF.

Amino Acids↗
PubMed1978

Role of contact inhibition in the regulation of receptor-mediated uptake of low density lipoprotein in cultured vascular endothelial cells.

Bovine vascular endothelial cells during logarithmic growth bind, internalize, and degrade low density lipoprotein (LDL) via a receptor-mediated pathway. However, contact-inhibited (confluent) monolayers bind but do not internalize LDL. This is in contrast to aortic smooth muscle cells or endothelial cells that have lost the property of contact inhibition. These cells internalize and degrade LDL at both high and low cell densities. The LDL receptors of smooth muscle and sparse endothelial cells down-regulate in response to LDL. In contrast, normal endothelial cells at confluency show little response. When contact inhibition in endothelial monolayers was locally released by wounding, and LDL was present, only cells released from contact inhibition accumulated LDL cholesterol. In smooth muscle cells under the same conditions, the entire culture interiorized lipid. It thus appears that in endothelial cells, unlike smooth muscle cells, contact inhibition is the major factor regulating cellular uptake of LDL cholesteryl ester. Reversal of contact inhibition by wounding provides a mechanism by which the endothelium could be the primary initiator of the atherosclerotic plaque.

Aorta↗
PubMed1978

Brain-derived fibroblast growth factor: identity with a fragment of the basic protein of myelin.

Fibroblast growth factors (FGF) isolated from bovine brain have been identified chemically and immunologically as components of the myelin basic protein. The intact bovine basic protein molecule (170 residues), prepared by the standard acid extraction procedure, lacked mitogenic activity (tested at concentrations up to 10 microgram/ml). However, the polypeptide FGF-2, identified as residues 44-153 of the basic protein, was maximally mitogenic for fibroblasts at 10 ng/ml and polypeptide 44-166 (FGF-1) was maximally active at 100 ng/ml. Pituitary-derived FGF is a potent a growth factor as FGF-2, but appears to be biochemically and immunologically distinct from brain-derived FGF. FGF released in the central or peripheral nervous system as a consequence of myelin damage and basic protein proteolysis could provide a physiological stimulus for wound healing and myelin repair.

Amino Acid Sequence↗
PubMed1978

Production a corpus luteum angiogenic factor responsible for proliferation of capillaries and neovascularization of the corpus luteum.

Factors controlling the changes in the vascular pattern of the ovary that occur during the reproductive cycle have been investigated. By using the rabbit cornea, the abilities of ovarian corpus luteum and of follicles to induce neovascularization have been compared. While the corpus luteum is capable of inducing neovascularization, the follicles do not have this ability. It is therefore likely that the corpus luteum actively participates in its own neovascularization by secreting a factor that we have called "corpus leutem angiogenic factor" (CLAF).

Angiogenesis Inducing Agents↗
PubMed1978

Identification, localization, and role of fibronectin in cultured bovine endothelial cells.

We have examined bovine aortic endothelial cell cultures for the presence of fibronectin, a high molecular weight cell-surface glycoprotein. Sparse cultures contain fibronectin only on dorsal cell surfaces at regions of cell-cell contact, as detected by immunofluorescence. In contrast, when the endothelial cells reached confluence as a highly contact-inhibited monolayer, fibronectin was detected in an extracellular matrix underneath the cell monolayer but not on top of the monolayer. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis of isolated extracellular matrix revealed that a predominant component of the matrix is a protein of approximately 2.3 X 10(5) molecular weight, which has been identified as fibronectin.

Basement Membrane↗
PubMed1978

Control of proliferation of human vascular endothelial cells. Characterization of the response of human umbilical vein endothelial cells to fibroblast growth factor, epidermal growth factor, and thrombin.

Because the response of human endothelial cells to growth factors and conditioning agents has broad implications for our understanding of wound healing angiogenesis, and human atherogenesis, we have investigated the responses of these cells to the fibroblast (FGF) and epidermal growth factors (EGF), as well as to the protease thrombin, which has been previously shown to potentiate the growth response of other cell types of FGF and EGF. Because the vascular endothelial cells that form the inner lining of blood vessels may be expected to be exposed to high thrombin concentrations after trauma or in pathological states associated with thrombosis, they are of particular interest with respect to the physiological role of this protease in potentiating cell proliferation. Our results indicate that human vascular endothelial cells respond poorly to either FGF or thrombin alone. In contrast, when cells are maintained in the presence of thrombin, their proliferative response to FGF is greatly increased even in cultures seeded at a density as low as 3 cells/mm2. Human vascular endothelial cells also respond to EGF and thrombin, although their rate of proliferation is much slower than when maintained with FGF and thrombin. In contrast, bovine vascular endothelial cells derived from vascular territories as diverse as the bovine heart, aortic arch, and umbilical vein respond maximally to FGF alone and neither respond to nor bind EGF. Furthermore, the response of bovine vascular endothelial cells to FGF was not potentiated by thrombin, indicating that the set of factors controlling the proliferation of vascular endothelial cells could be species-dependent. The requirement of cultured human vascular endothelial cells for thrombin could explain why the human cells, in contrast to bovine endothelial cells, are so difficult to maintain in tissue culture. Our results demonstrate that by using FGF and thrombin one can develop cultures of human vascular endothelial cells capable of being passage repeatedly while maintaining a high mitotic index. The stock cultures used for these studies have been passed weekly with a split ratio of 1 to 10 and are currently in their 30th passage. These cultures are indistinguishable from earlier passages when examined for the presence of Weibel-Palade bodies or Factor VIII antigen. We conclude that the use of FGF and thrombin can prevent the precocious senescence observed in most human endothelial cells cultures previously described.

Animals↗
PubMed1978

The effects of the epidermal and fibroblast growth factors on the replicative lifespan of cultured bovine granulosa cells.

The effects of fibroblast growth factor (FGF) and epidermal growth factor (EGF) on the lifespan of cultured bovine granulosa cell cultures have been investigated. Granulosa cell cultures from small follicles (4-7 mm) had a lifespan of 11-12 generations, whereas the lifespan of cultures originating from large follicles did not exceed seven generations. The addition of either EGF or FGF to the medium of cultures originating from small follicles greatly increased the lifetime of the cultures, which can then exceed 60 generations. A similar, although less pronounced, effect was observed with cultures originating from large follicles. The lifespan of granulosa cell cultures depends upon the presence of FGF or EGF in the medium, as the deletion of the mitogens resulted in rapid terminal differentiation and a shortened replicative lifespan. As either FGF or EGF can prolong the replicative lifespan of granulosa cell cultures, it is suggested that limited replicative lifespan when maintained in the absence of mitogens is not so much determined by a fixed rate of mutation as it is by the culture conditions in which the cells are maintained.

Animals↗