PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Corneal Stroma”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1992

beta-D xyloside alters dermatan sulfate proteoglycan synthesis and the organization of the developing avian corneal stroma.

Corneal transparency is dependent upon the development of an organized extracellular matrix containing small diameter collagen fibrils with regular spacing, organized as orthogonal lamellae. Proteoglycan-collagen interactions have been implicated in the regulation of collagen fibrillogenesis and matrix assembly. To determine the role of dermatan sulfate proteoglycan in the development and organization of the secondary corneal stroma, its synthesis was disrupted using beta-D xyloside. The secondary corneal stroma contains two different proteoglycans, dermatan sulfate and keratan sulfate proteoglycan. beta-D xyloside interferes with xylose-mediated O-linked proteoglycan synthesis, and thus disrupts dermatan sulfate proteoglycan synthesis. Corneal keratan sulfate proteoglycan, a mannose-mediated N-linked proteoglycan, should not be altered. Biochemical analysis of corneas treated both in vitro and in ovo revealed a reduced synthesis of normally glycosylated dermatan sulfate proteoglycans and an increased synthesis of free xyloside-dermatan sulfate glycosaminoglycans. Keratan sulfate proteoglycan synthesis was unaltered in both cases. Corneal stromas were studied using histochemistry and electron microscopy after in ovo treatment with beta-D xyloside. The observed biochemical alterations in dermatan sulfate proteoglycans translated into disruptions in the organization of beta-D xyloside-treated stromas. There was a reduction in the histochemical staining of proteoglycans, but no alteration in collagen fibril diameter. In addition, focal alterations in collagen fibril packing, and a disruption of lamellar organization were observed in beta-D xyloside-treated corneas. These data suggest that dermatan sulfate proteoglycans are not involved in the regulation of corneal collagen fibril diameter, but are important in the fibril-fibril spacing as well as in lamellar organization, and cohesiveness.

Animals↗
PubMed2005

Multipotent stem cells in human corneal stroma.

Keratocytes of the corneal stroma secrete a specialized extracellular matrix essential for vision. These quiescent cells exhibit limited capacity for self-renewal and after cell division become fibroblastic, secreting nontransparent tissue. This study sought to identify progenitor cells for human keratocytes. Near the corneal limbus, stromal cells expressed ABCG2, a protein present in many adult stem cells. The ABCG2-expressing cell population was isolated as a side population (SP) by cell sorting after exposure to Hoechst 33342 dye. The SP cells exhibited clonal growth and continued to express ABCG2 and also PAX6, product of a homeobox gene not expressed in adult keratocytes. Cloned SP cells cultured in medium with fibroblast growth factor-2 lost ABCG2 and PAX6 expression and upregulated several molecular markers of keratocytes, including keratocan, aldehyde dehydrogenase 3A1, and keratan sulfate. Cloned corneal SP cells under chondrogenic conditions produced matrix staining with toluidine blue and expressed cartilage-specific markers: collagen II, cartilage oligomatrix protein, and aggrecan. Exposure of cloned SP cells to neurogenic culture medium upregulated mRNA and protein for glial fibrillary acidic protein, neurofilament protein, and beta-tubulin II. These results demonstrate the presence of a population of cells in the human corneal stroma expressing stem cell markers and exhibiting multipotent differentiation potential. These appear to be the first human cells identified with keratocyte progenitor potential. Further analysis of these cells will aid elucidation of molecular mechanisms of corneal development, differentiation, and wound healing. These cells may be a resource for bioengineering of corneal stroma and for cell-based therapeutics.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2004

[Reconstruction of rabbit corneal stroma using tissue engineering technique].

OBJECTIVE: Reconstruct corneal stroma by tissue engineering. METHODS: Primary corneal stromal cells were isolated from newborn rabbit cornea. When the cultured cells reaching confluence, the stromal cells were mixed with polyglycolic acid (PGA) to form a cell-scaffold construct. After 1 week in vitro culture, the constructs were implanted into mother rabbit corneal stroma. Parts of corneal stromal cells were transfected with GFP gene as mark of transplanted cells. Tissues were harvested at 8 weeks for transmission electron microscopy (TEM), histology and Western blot evaluation. In control, PGA alone was implanted into the other cornea. RESULTS: The engineered corneal stroma became transparent gradually over a period of 8 weeks. The histology of engineered stromal lamellar was relatively similar to that of natural one, no significant differences were found in the diameter of cornea collagen fiber [(29.4 +/- 4.7) nm] in experimental rabbits compared with control [(28.5 +/- 3.5) nm], Student's t-test: P = 0.1316 > 0.05. TEM demonstrated that collagen fibrils deposited in engineered stroma had a similar diameter compared to that of normal counterpart. In addition, Western blot showed the positive expression of type I collagen in the collagen fibrils. In contrast, no new stroma tissue was formed when PGA alone implanted. A green colored stroma was observed when engineered with GFP-labeled cells under fluorescence light microscope. CONCLUSION: The results demonstrate that nearly transparent corneal stroma can be obtained by the technique of cornea engineering.

Animals↗
PubMed2002

Identification of a novel macrophage population in the normal mouse corneal stroma.

PURPOSE: To examine the normal murine corneal stroma for the presence of bone marrow-derived leukocytes. METHODS: Wholemounts of paraformaldehyde-fixed corneal stroma from normal mice at 5 to 16 weeks of age were examined in single- and double-color immunomorphologic studies performed with confocal microscopy. The phenotype, morphology, distribution, and density of immunopositive cells were determined. RESULTS: Numerous CD45(+) cells with pleomorphic and dendriform morphology were found within the pericentral and central region of the corneal stroma (200-300 cells/mm(2)). Dual-color immunostaining demonstrated that 100% of the CD45(+) cells coexpressed CD11b and 50% coexpressed F4/80. Approximately 30% of the total cells and 50% of the F4/80(+) cells coexpressed major histocompatibility complex (MHC) class II antigens. Very small to negligible numbers of cells expressed markers of dendritic cells (CD11c) or granulocytes (Ly6G). Markers for T-cells and NK cells were absent from the corneal stroma, indicating that all the cells identified in the stroma were of the myeloid lineage. CONCLUSIONS: The normal murine corneal stroma contains a significant number of CD45(+) leukocytes. Most these cells express the CD11b marker, but not other dendrite, granulocyte, T-cell, or NK markers, placing them in the monocyte/macrophage lineage.

Animals↗
PubMed1989

Air-injection of the corneal stroma: a SEM study.

The corneal stroma is supposed to be a homogeneous structure both from an optical and an anatomical point of view. Intrastromal injection of glutaraldehyde as a fixative causes local swelling and opacification of the corneal tissue. Local injections of small volumes of air superficially and more deeply into the corneal stroma produce similar swellings and formation of opaque areas. SEM investigation of these areas shows the existence of stromal canals, partly pre-existing, partly caused by the internal 'explosions' due to the air-injection. This suggests an anatomically non-homogeneous, although optically homogeneous, cornea.

Air↗
PubMed2006

CXCL1/KC and CXCL5/LIX are selectively produced by corneal fibroblasts and mediate neutrophil infiltration to the corneal stroma in LPS keratitis.

The severity of corneal inflammation depends on the activity of infiltrating neutrophils responding to chemotactic factors such as CXC chemokines. This study examines the relative contribution of CXCL1/keratinocyte-derived chemokine (KC), CXCL2/monocyte-inhibitory protein-2 (MIP-2), and CXCL5/LPS-induced chemokine (LIX) in neutrophil recruitment to the corneal stroma during LPS keratitis, where neutrophils infiltrate the corneal stroma at 6 h after LPS injection and peak at 24 h. Consistent with this timeframe, KC was detected after 3 h, reached peak levels at 24 h, and decreased thereafter. In contrast, LIX production was not detected until 8 h after injection and peaked at 24 h. MIP-2 was detected at 3 h but did not reach the levels of KC and LIX. Cell types associated with corneal inflammation produced markedly different chemokines in vitro: Murine corneal fibroblasts (MK/T-1) produced LIX and KC in response to LPS but did not produce MIP-2, whereas peritoneal macrophages and neutrophils produced MIP-2 and KC but did not produce LIX. To determine the role of these chemokines in neutrophil recruitment to the cornea, anti-LIX, anti-KC, or anti-MIP-2 was injected into the corneal stroma of enhanced GFP chimeric mice prior to LPS, and total cell and neutrophil infiltration was examined. Antibody to LIX and KC, injected individually or in combination, significantly inhibited neutrophil recruitment to the cornea, whereas anti-MIP-2 had no inhibitory effect. Together, these findings demonstrate cell-specific production of CXC chemokines and show that LIX and KC mediate neutrophil recruitment into the cornea during LPS keratitis.

Animals↗
PubMed2001

[Reconstruction of corneal stroma using tissue engineering technique].

OBJECTIVE: To reconstruct new corneal stroma in order to provide a basis for future studies on the reconstruction of cornea. METHODS: The cultured corneal stromal cell-PGA complex was grafted to the subdermis of a female balb/c nude mouse. Six weeks after grafting, the new reformed tissue was fixed for histologic examination and transmission electron microscopy (TEM). At the same time, the new deposited collagen fibril diameter was measured. RESULTS: The reconstructed corneal stromal layer was formed in a waved, crossed-web structure, which was similar to the normal corneal stroma. Cell deposited collagen fibrils were similar in diameter to those seen in normal corneal stroma. CONCLUSIONS: The corneal stroma can be reconstructed by using tissue engineering technique. The reconstructed tissue which is similar to the normal cornea in key characteristics, including morphology and histologic structure provides an ideal experimental model for corneal physiological, pathologic, toxic and drug efficient testing and for future development of the tissue for implantation.

Animals↗
PubMed2002

[A primary study on soluble protein and soluble antigen of corneal stroma in Mooren ' s ulcer patients].

OBJECTIVE: To investigate changes of soluble protein and soluble antigen of corneal stroma in Mooren's ulcer patients and autoantibody in the patients' sera against the soluble antigen. METHODS: The corneal stromal specimens taken from 15 Mooren's ulcer patients who received lamellar keratoplasty were studied. Soluble protein and soluble antigen of the corneal stroma were extracted. The soluble protein contents were measured. The soluble corneal stromal extracts were tested by using sodium dodecyl sulfate polyacrylamide gel electrophoresis technique (SDS-PAGE). The protein strips of electrophoresis were analyzed using thin layer scanning system. Peripheral vein blood of 15 patients with Mooren's ulcer was taken. Indirect enzyme linked immunosorbent assay (ELISA) was used to test the level of autoantibody in the patients' sera against the soluble antigen of the corneal stroma. RESULTS: Soluble protein contents of corneal stroma extracts were 0.435 mg/L in the patient group and 0.645 mg/L in the normal control group. SDS-PAGE results of the affected corneal stromal extracts showed that a protein about 12 000 of molecular weight appeared at 0.92 of Rf. 12 000 protein was not found in the control group. The content of 12 000 protein was 22.1% of the total soluble protein of the involved corneal stroma. The level of autoantibody in the patients' sera against the soluble antigen was much higher than that of normal control (t = 15.15,P < 0.001). CONCLUSIONS: The appearance of 12 000 protein in the soluble protein of the involved corneal stroma may have a connection with the soluble corneal stromal antigen. The level of the autoantibody in the patients' sera against the soluble antigen is significantly higher than that of the control. It represents that Mooren's ulcer patients have an autoimmune reaction to the corneal stroma.

Adult↗
PubMed1993

Long-spacing collagen in the human corneal stroma.

An electron microscopic observation of a corneal lenticule removed 14 months after epikeratoplasty because of refractive error and an unused lenticule was carried out to determine the presence of long-spacing collagen. In the removed lenticule, long-spacing collagen, which is often described as the product of the keratocytes migrating from the host corneal stroma, was observed near a keratocyte. However, long-spacing collagen was also observed in the unused lenticule. In this specimen, keratocytes had been destroyed by freezing so that the secretion of long-spacing collagen by keratocytes should have been negligible. Thus, it seemed that long-spacing collagen could exist naturally in the corneal lenticule as well as be newly formed by migrating keratocytes. In addition, we examined four corneas from patients ranging from 2 months to 91 years of age with no past history of corneal diseases or disorders. Long-spacing collagen was seen in the corneal stromas of the aged persons, but not in those of the younger. In the corneas of the 78-year- and 91-year-old, a different appearance from the usual long-spacing collagen was also seen in the collagen fibrils which showed a slightly shorter periodicity resembling experimentally formed 100 nm periodic fibrils in mice. Long-spacing collagen is a common component of normal human corneal stroma and its occurrence seems to correlate with the age-related changes of the tissue.

Aged↗
PubMed2001

MK/T-1, an immortalized fibroblast cell line derived using cultures of mouse corneal stroma.

PURPOSE: Immortalized cell lines representing fibroblast cells from corneal stroma would facilitate studies of corneal cell biology and injury response. METHODS: Primary cultures of cells derived from mouse corneal stroma were transfected with a human telomerase reverse transcriptase (hTERT) expression construct to maximize chances of cellular immortalization. A resulting cell line was analyzed for telomerase activity, cell growth characteristics, senescence and gene expression patterns. Specific responses to transforming growth factor beta (TGF-beta) were also analyzed. RESULTS: An immortalized cell line was derived and was named MK/T-1. MK/T-1 cells show no signs of cellular senescence or transformation at over 100 passages. Telomerase activity was significantly higher in MK/T-1 cells as compared to the parental cell cultures. However, relative telomere length (RTL) in the MK/T-1 and parental cells was not significantly different. Senescence associated beta-galactosidase (SA-beta-Gal) activity was not detected in late passage MK/T-1 cells while the parental cells had already upregulated SA-beta-Gal at high levels by passage 9. The MK/T-1 cells express vimentin, tubulin, lumican, mimecan, decorin and collagen I, but not keratocan. Exposure of the MK/T-1 cells to TGF-beta induces the expression of smooth muscle alpha-actin (ASMA), the activation of MAP Kinase (p38-MAPK) and morphological changes consistent with cytoskeletal reorganization. CONCLUSIONS: MK/T-1 cells represent an immortalized fibroblast cell line derived using cultures from corneal stroma cell preparations. Expression of hTERT may contribute to immortalization of the MK/T-1 cells by a mechanism other than increases in RTL. MK/T-1 cells may be a useful model in which to study the responses of corneal fibroblast cells to cytokines and other diverse environmental factors in vitro.

Animals↗
PubMedDate not supplied

Isolation and preliminary characterization of a structural glycoprotein complex from bovine corneal stroma.

After extraction of bovine corneal stroma with 1M CaC1(2) and subsequent digestion of the insoluble residue with purified bacterial collagenase, two crude structural glycoprotein (SPG) fractions were obtained; one which precipitated upon dialysis against water of the collagenase solubilized material and the other which was extracted by 8M urea from the collagenase insoluble material. Amino acid analyses of these crude SGP fractions indicated that they were primarily non-collagenous but that very small amounts of collagen-derived amino acids were present. Upon gel filtration of these SGP fractions on Sepharose 4B-CL, void volume fractions were isolated from each of the crude fractions which were enriched, relative to the original crude fractions, in the collagen-derived amino acids. Carbohydrate analysis indicated that the void volume fractions had the properties of glycoproteins rather than proteoglycans. Upon disulfide reduction and SDS-PAGE, each of these fractions was resolved into five major protein bands with molecular weights of 155,000, 137,000, 117,000 82,000 and 34,000. Only the three largest bands contained the collagen derived amino acids. These data are consistent with the presence within bovine corneal stroma of a large structural glycoprotein complex comprised of at least five protein components associated through disulfide bonds. Collagen apparently is associated with three of these, either through covalent crosslinkage, or as part of the primary structure.

Amino Acids↗
PubMed2005

[Preparation of xenogenic corneal stroma and its cytoconsistency].

OBJECTIVE: To explore the possibility that using the bovine corneal stroma to provide a suitable carrier on which the cells can grow for tissue engineering cornea. METHODS: Nine fresh bovine corneas were selected. Each cornea was cut into 2 pieces, and exposed to 0.25% trypsinase for various lengths of time (20 minutes, 40 minutes, and 60 minutes) to get the stroma part with least cells and maintaining the collagen fibers arrangement. Samples obtained from each group were examined with scanning electron microscopy and HE staining. The left ones were freeze-dried and sterilized. The various concentrations of extraction were used to cultivate human fibroblasts, and a 3-(4,5-dimethylthiazol-2-yl)-2, (MTT)-based colorimetric assay was taken to evaluate the exhistance of 5-diphenyltetrazolium bromide cytotoxinic effects. Then the proper corneal stroma was used as a carrier to cultivated the rabbit corneal limbal cells which were planted on it in a concentration of 2 x 10(5)/cm2 in vitro. The cell-carrier samples were sent for scanning electron microscopy and HE staining. RESULTS: The corneal stroma had the least cells in the group acted with typsin for 60 minutes, while the collagen fibers arrangement was not so orderly as before. The extractions showed no significant difference in cell culture, and no obviously harmful effect on the cell growth. The rabbit corneal limbal cells presented a stratified growth on the bovine corneal stroma. CONCLUSION: The bovine corneal stroma without cells prepared using the typsin and lyophilization can be a suitable carrier for cell culture in vitro.

Animals↗
PubMed1996

Transplanted corneal stromal cells in vitreous reproduce extracellular matrix of healing corneal stroma.

PURPOSE: To characterize the extracellular matrix (ECM) formed by corneal stromal cells after injection into the vitreous. This will provide a basis for future studies on the function of corneal ECM macromolecules. METHODS: Cell line from rabbit dermal fibroblasts (RAB9) and primary cultures of rabbit corneal stroma fibroblasts (NRCF) were grown to confluence. For each cell type, approximately 1 x 10(6) cells suspended in basal medium were injected into the vitreous of normal rabbits and observed periodically with a slit lamp. After 1,2, and 4 weeks, eyes were processed for transmission electron microscopy (TEM), immunohistochemistry, immunocytochemistry, and in situ hybridization. RESULTS: All cells showed gradual growth within the vitreous along the needle track. Occurrence of retinal detachment and inflammation was variable. Transmission electron microscopy of NRCF confirmed the deposition of ECM reminiscent of the organization of normal fetal corneal stroma. Similar matrices were produced by RAB9. NRCF deposited collagen fibrils similar in diameter to those seen in normal developing and healing corneal stroma. RAB9 produced collagen fibrils with larger diameters. NRCF-transplanted cells synthesized proteoglycans and collagen immunologically identical to decorin proteins and type VI collagen, indicating that the expression of specific ECM is maintained after transplantation. In addition, in situ hybridization showed that type XII collagen mRNA is synthesized by transplanted NRCF similar to healing corneas. CONCLUSIONS: Corneal stromal cells transplanted into vitreous produce a matrix morphologically and biochemically similar to that in healing corneal stroma.

Animals↗
PubMed2006

[The reconstruction of bioengineer active corneal stroma and its biocompatibility study].

This paper aims to explore the biocompatibility of bioengineer active corneal stroma (BACS), as the biological carrier for cornea reconstruction, to provide the basis for future study on clinic application. The cells and immunogenic components of cornea stroma were removed through different extract methods. A complex of functional corneal stroma cells and acellular corneal stroma was used to reconstruct BACS. Their morphological characteristics and ultrastructures were observed with transmission electron microscope. The complex was grafted into interlamellar stromal pockets. Cells were labeled by BrdU to examine the survival and conversion after grafting. The cells could survive and proliferate in acellular corneal stroma. All the nuclei of the corneal stromal cells showed positive labeling with BrdU in the BACS. After 4 weeks, BACS became transparent; after 8 weeks, the bioengineer active cornea stroma was fully reconstructed.

Animals↗
PubMed2003

Histologic evaluation of corneal stroma in rabbits after intrastromal corneal ring implantation.

PURPOSE: Previous refractive corneal implants have produced histologic changes characteristic of nonspecific lipid keratopathy. Intacs intrastromal corneal ring segments are polymethylmethacrylate (PMMA) corneal inserts approved for the correction of low myopia by the U.S. Food and Drug Administration. The purpose of this study was to describe histologic changes associated with these corneal implants in rabbit eyes. METHODS: Two 150-degree PMMA arc segments, 0.30 mm thick, were surgically implanted through a single radial incision at two-thirds stromal depth in the mid-peripheral cornea of five New Zealand white rabbits. We collected corneas 6 months after implantation that were prepared for light and electron microscopy. We analyzed tissue with oil red O, filipin, and periodic acid-Schiff (PAS) staining. Additional studies with energy-dispersive x-ray analysis and autofluorescent microscopy were conducted. RESULTS: In all samples, we observed new collagen formation with lamellar organization adjacent to the implant and increased keratocyte density. Intracellular accumulations of osmophilic and saturated lipid material corresponded to stromal opacification visible by slit-lamp microscopy. These same regions were autofluorescent and stained positively with oil red O, and filipin but negatively with PAS. Granular lipid inclusions characteristic of lipofuscinosis were absent on transmission electron microscopy. Energy-dispersive x-ray analysis demonstrated elevated levels of calcium compared with adjacent tissue. CONCLUSION: Tissue response to these corneal inserts includes keratocyte activation, intracellular lipid accumulation, and new collagen formation. Our histologic findings suggest that these deposit formations are not lipofuscin accumulations.

Animals↗