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Shigeto Shimmura

Publications and source records attributed to Shigeto Shimmura.

At least 19 recordsLinked to original sources
PubMed2007

Amniotic membrane immobilized poly(vinyl alcohol) hybrid polymer as an artificial cornea scaffold that supports a stratified and differentiated corneal epithelium.

Poly(vinyl alcohol) (PVA) is a biocompatible, transparent hydrogel with physical strength that makes it promising as a material for an artificial cornea. In our previous study, type I collagen was immobilized onto PVA (PVA-COL) as a possible artificial cornea scaffold that can sustain a functional corneal epithelium. The cellular adhesiveness of PVA in vitro was improved by collagen immobilization; however, stable epithelialization was not achieved in vivo. To improve epithelialization in vivo, we created an amniotic membrane (AM)-immobilized polyvinyl alcohol hydrogel (PVA-AM) for use as an artificial cornea material. AM was attached to PVA-COL using a tissue adhesive consisting of collagen and citric acid derivative (CAD) as a crosslinker. Rabbit corneal epithelial cells were air-lift cultured with 3T3 feeder fibroblasts to form a stratified epithelial layer on PVA-AM. The rabbit corneal epithelial cells formed 3-5 layers of keratin-3-positive epithelium on PVA-AM. Occludin-positive cells were observed lining the superficial epithelium, the gap-junctional protein connexin43-positive cells was localized to the cell membrane of the basal epithelium, while both collagen IV were observed in the basement membrane. Epithelialization over implanted PVA-AM was complete within 2 weeks, with little inflammation or opacification of the hydrogel. Corneal epithelialization on PVA-AM in rabbit corneas improved over PVA-COL, suggesting the possibility of using PVA-AM as a biocompatible hybrid material for keratoprosthesis.

3T3 Cells↗
PubMed2006

SOCS3 is required to temporally fine-tune photoreceptor cell differentiation.

Suppressor of cytokine signaling 3 (SOCS3) is an intracellular, ligand-induced negative feedback modulator of STAT3 activation that acts during inflammation. Here, we demonstrate that SOCS3 expression is important for normal retinal development in the perinatal period. STAT3 is highly activated in the late-embryonic retina, then downregulated at postnatal day 0 (P0), presumably by the depletion of upstream ligands. We found that SOCS3 was required after P0 to shut down the residual STAT3 activation; this loss of activated STAT3 leads to Rhodopsin expression and rod photoreceptor cell differentiation. SOCS3 deficiency failed to terminate STAT3 activation, thereby delaying expression of Rhodopsin and its upstream transcription factor, crx. Development subsequently continued, but its course was temporally erratic, probably because of faulty compensation. Interestingly, SOCS3 protein expression was first detected postnatally, after STAT3 activation was mostly downregulated. It initially appeared in some of the presumptive photoreceptor cells and gradually spread. SOCS3 mRNA level was constant from the late-embryonic to early-postnatal period. Post-transcriptional inhibition of SOCS3 protein expression maintains a high STAT3 activation during late embryogenesis, and after P0, releasing from the inhibition promptly terminates STAT3 activation. Thus, SOCS3 can act as a temporal fine-tuner of STAT3 activation during photoreceptor cell differentiation.

Animals↗
PubMed2006

Isolation of multipotent neural crest-derived stem cells from the adult mouse cornea.

We report the presence of neural crest-derived corneal precursors (COPs) that initiate spheres by clonal expansion from a single cell. COPs expressed the stem cell markers nestin, Notch1, Musashi-1, and ABCG2 and showed the side population cell phenotype. COPs were multipotent with the ability to differentiate into adipocytes, chondrocytes, as well as neural cells, as shown by the expression of beta-III-tubulin, glial fibrillary acidic protein, and neurofilament-M. COP spheres prepared from E/nestin-enhanced green fluorescent protein (EGFP) mice showed induction of EGFP expression that was not originally observed in the cornea, indicating activation of the neural-specific nestin second intronic enhancer in culture. COPs were Sca-1(+), CD34(+), CD45(-), and c-kit(-). Numerous GFP(+) cells were observed in the corneas of mice transplanted with whole bone marrow of transgenic mice ubiquitously expressing GFP; however, no GFP(+) COP spheres were initiated from these mice. On the other hand, COP spheres from transgenic mice encoding P0-Cre/Floxed-EGFP as well as Wnt1-Cre/Floxed-EGFP were GFP(+), indicating the neural crest origin of COPs, which was confirmed by the expression of the embryonic neural crest markers Twist, Snail, Slug, and Sox9. Taken together, these data indicate the existence of neural crest-derived, multipotent stem cells in the adult cornea.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2006

Proteomic analysis of soluble factors secreted by limbal fibroblasts.

PURPOSE: To identify soluble factors selectively secreted by limbal fibroblasts as possible regulators of limbal basal epithelium. METHODS: Limbal, corneal, and conjunctival fibroblasts were first expanded in vitro in Dulbecco's modified Eagle medium containing 10% fetal bovine serum, and then maintained in serum-free medium for two weeks. Proteomic analysis of culture supernatants was done to compare differences in secreted matricellular proteins. Real time PCR and western blots were done to confirm the expression of secreted protein acid and rich in cysteine (SPARC), a protein found in abundance in extracellular proteins secreted by limbal fibroblasts. Immunohistochemistry of SPARC was done in human limbal tissue to show the spatial distribution of the protein. An adhesion assay was designed to demonstrate the effects of SPARC on an SV40 immortalized human corneal epithelial cell line (HCEC). RESULTS: Proteomic analysis revealed several proteins selectively secreted by limbal fibroblasts. The particular spots were identified as SPARC, vimentin, serine protease, collagen alpha 2 precursor, tissue inhibitor of metalloproteinase 2 (TIMP-2), and 5,10-methlenetetrahdrofolate reductase (FADH2). The expression of SPARC was confirmed by western blot analysis, and mRNA expression was significantly higher in limbal fibroblasts compared to central corneal fibroblasts when analyzed by real time PCR. Immunohistochemistry revealed higher distribution of SPARC in the subepithelial stroma of the limbus compared to the central cornea. The addition of 10 microg/ml murine SPARC in HCEC significantly reduced cell spreading at three h. CONCLUSIONS: The matricellular protein SPARC is preferentially secreted by limbal fibroblasts, and may modulate intercellular adhesion of basal limbal epithelial cells.

Animals↗
PubMed2006

Long-standing bullous keratopathy is associated with peripheral conjunctivalization and limbal deficiency.

OBJECTIVE: To investigate whether peripheral corneal neovascularization in bullous keratopathy (BK) is due to conjunctivalization, a sign of limbal stem cell deficiency. DESIGN: Observational case-control study. PARTICIPANTS: Sixteen BK patients. METHODS: Patients were divided into 2 groups: BK without peripheral neovascularization [NV(-) group; 5 patients, 5 eyes] and BK with neovascularization [NV(+) group; 11 patients, 13 eyes]. Evidence of conjunctivalization was evaluated by periodic acid-Schiff staining of impression cytology samples from the peripheral vascularized cornea. The 2 groups' durations of disease also were compared. Penetrating keratoplasty (PK) was performed in all 16 cases, and the 2 groups' durations of reepithelialization after PK were compared. MAIN OUTCOME MEASURES: Presence of goblet cells using impression cytology, duration of BK, and duration of postoperative reepithelialization. RESULTS: Goblet cells were found on the peripheral corneal surface in all eyes in the NV(+) group. However, all eyes in the NV(-) group were negative for goblet cells (P<0.0001). Duration of disease was 14.4+/-5.4 months in the NV(-) group and 66.2+/-65.5 months in the NV(+) group (P = 0.030). Duration of postoperative epithelialization was 6.2+/-2.2 days in the NV(-) group and 28.8+/-36.5 days in the NV(+) group (P = 0.046). CONCLUSION: Conjunctivalization of the peripheral cornea and delayed postoperative epithelialization in BK patients with NV suggest the presence of limbal stem cell deficiency in such patients. Patients with long-standing disease were found to be more prone to neovascularization. For this reason, early surgery may lead to a better surgical outcome.

Aged↗
PubMed2006

Dacryoadenitis associated with Acanthamoeba keratitis.

OBJECTIVE: To report the incidence of dacryoadenitis as a symptom associated with Acanthamoeba keratitis. METHODS: We investigated all cases of Acanthamoeba keratitis (20 patients and 21 eyes) diagnosed and treated at Tokyo Dental College, Ichikawa General Hospital, Ichikawa, Japan, between May 1, 1994, and November 30, 2005. We recorded the incidence of dacryoadenitis diagnosed using clinical signs of lacrimal gland swelling and pain on pressure, computed tomography, magnetic resonance imaging, and histopathologic analysis. RESULTS: Eight eyes (38%) of 8 patients had dacryoadenitis simultaneously with Acanthamoeba keratitis. Dacryoadenitis was diagnosed using histopathologic analysis and computed tomography in 1 patient, histopathologic analysis and magnetic resonance imaging in 1, magnetic resonance imaging in 2, and clinical signs alone in 4. Histopathologic examination in 2 patients revealed moderate infiltration of lymphocytes and plasma cells in the lacrimal gland compatible with dacryoadenitis. No Acanthamoeba organisms were found in the lacrimal gland. The standard protocol for Acanthamoeba keratitis was performed without particular treatment of dacryoadenitis in all patients. Lacrimal gland swelling improved after a mean of 10 weeks (range, 4-17 weeks) in conjunction with symptoms of keratitis; however, 1 patient (patient 1) required levator muscle surgery and blepharoplasty for residual ptosis. CONCLUSION: Dacryoadenitis is a clinical finding associated with Acanthamoeba keratitis.

Acanthamoeba Keratitis↗
PubMed2006

Collagen-immobilized poly(vinyl alcohol) as an artificial cornea scaffold that supports a stratified corneal epithelium.

The cornea is a transparent tissue of the eye, which is responsible for the refraction of incoming light. Both biological corneal equivalents and synthetic keratoprostheses have been developed to replace donor tissue as a means to restore vision. However, both designs have drawbacks in terms of stability and biocompatibility. Clinically available synthetic devices do not support an intact epithelium, which poses a risk of microbial infection or protrusion of the prosthesis. In the present study, type I collagen was immobilized onto poly(vinyl alcohol) (PVA-COL) as a possible artificial cornea scaffold that can sustain a functional corneal epithelium. Human and rabbit corneal epithelial cells were air-lift cultured with 3T3 feeder fibroblasts to form a stratified epithelial layer on PVA-COL. The epithelial sheet expressed keratin 3/12 differentiation markers, the tight junction protein occludin, and had characteristic microvilli structures on transmission electron microscopy. Functionally, the stratified epithelium contained normal glycogen levels, and an apical tight-junction network was observed to exclude the diffusion of horseradish peroxidase. Furthermore, the epithelium-PVA-COL composite was suturable in the rabbit cornea, suggesting the possibility of using PVA-COL as a biocompatible material for keratoprosthesis.

Animals↗
PubMed2006

Comparison of deep lamellar keratoplasty and penetrating keratoplasty for lattice and macular corneal dystrophies.

PURPOSE: To compare the therapeutic outcomes after deep lamellar keratoplasty (DLKP) and penetrating keratoplasty (PKP) in patients with lattice corneal dystrophy (LCD) and macular corneal dystrophy (MCD). DESIGN: Age-matched control study. METHODS: We reviewed the clinical records of 84 eyes with LCD or MCD who had DLKP (41 eyes) or PKP (43 eyes). Primary pathology consisted of 60 eyes with LCD and 24 eyes with MCD. DLKP was performed by either removing stromal tissue gradually, or by viscodissection of Descemet's membrane. Graft clarity, best-corrected visual acuity (BCVA), endothelial density, and complications were compared between DLKP and PKP, as well as between LCD and MCD. RESULTS: All 84 eyes showed a postoperative improvement in visual acuity. The median final BCVA was not significantly different between PKP and DLKP groups. Endothelial cell loss rates were similar for DLKP and PKP. While the MCD-DLKP group showed progressive decrease in endothelial density, this was not observed in the LCD-DLKP group after surgery. In the DLKP group, most of the complications occurred intraoperatively or in the early phase, whereas late phase complications such as endothelial rejection and secondary glaucoma were the main complications in the PKP group. CONCLUSIONS: PKP is no longer an automatic choice for the surgical treatment for LCD and MCD; DLKP seems to be a safe alternative. While DLKP is a favorable method for LCD, MCD may not be a good candidate, as it might show progressive decrease in the corneal endothelium postoperatively.

Adult↗
PubMed2006

Accessory cell populations in the cornea.

According to the "classical" doctrine, resident cells of the cornea include the stratified epithelial cells, quiescent keratocytes, and a single layer of nondividing endothelial cells. However, it has become increasingly evident that other cell types are involved in the homeostasis of the cornea. The presence of various cell types from different lineages has raised concern among researchers as to what we are actually "seeing" in the cornea. Although definitive conclusions cannot yet be drawn, this review attempts to clarify the various accessory cell types reported in the human and murine cornea. The epithelial layer of the limbal area includes melanocytes, as well as antigen-presenting cells that are also present in the peripheral clear cornea. The most debated tissue currently is perhaps the corneal stroma, where resident keratocytes are not as large a population as was previously believed. Bone marrow-derived cells are found in the cornea, and these may not express the typical HLA molecules usually found on the surface of antigen-presenting cells. Nerve fibers extend though the superficial stroma to form a plexus beneath the epithelium. Although the cell body of the neuron itself is not in the cornea, neural glial cells, such as Schwann cells, are present in the stroma. The use of specific molecular markers and high-quality imaging techniques will be required to fully elucidate the various accessory cells of the cornea and their function.

Animals↗
PubMed2006

Changes observed in keratolimbal allograft.

OBJECTIVE: To study the incidence and clinical characteristics of presumed immunologic reactions in limbal grafts after keratolimbal allograft(KLAL). METHODS: A total of 121 KLALs performed in consecutive 85 eyes of 78 patients with total limbal stem-cell deficiency were analyzed retrospectively. Mean follow-up period was 46.6 months. Three types of limbal graft changes classified as epithelial defects, acute edema, and vascular engorgement were analyzed as probable signs of immunologic rejection. RESULTS: One or more changes in limbal grafts were observed after 16 KLALs (13.1%). All but 1 eye used systemic and local immunosuppression using corticosteroid and cyclosporine A, and most of the changes developed within 3 months postoperatively. All but 2 eyes developed epithelial breakdown in the central cornea, and 12 corneas underwent conjunctivalization. The rate of corneal epithelialization in eyes with limbal graft changes was significantly worse than those without the changes (P < 0.0001). Histologic examination in eyes with the limbal graft changes revealed high incidence of lymphocyte infiltration. CONCLUSIONS: Presumed limbal graft rejection occurred in approximately 13% of cases after KLAL. Suppression of the immune reaction remains a key to success in KLAL.

Adolescent↗
PubMed2006

Ocular surface reconstruction for thermal burns caused by fireworks.

PURPOSE: To describe 6 eyes with severe firework-related ocular surface injuries that were treated by limbal stem cell transplantation combined with amniotic membrane transplantation (AMT). METHODS: Six eyes of 6 patients with firework-related ocular injuries were retrospectively studied. All subjects were men, with age ranging from 9 to 26 years. All patients were in chronic stage of thermal injury, and all had total limbal stem cell dysfunction and subsequent conjunctival fibrosis. They had limbal stem cell transplantation (1 had an allograft and 5 had autograft transplantation) combined with AMT to restore vision. Mitomycin C was used in 1 eye intraoperatively. RESULTS: After ocular surface reconstruction using limbal stem cell transplantation combined with AMT, corneal epithelialization was achieved in 4 eyes after a mean duration of 20.8 +/- 12.2 days (range, 4-33 days). After a mean follow-up period of 36 months (range, 5-87 months), marked reduction of fibrosis was noted in all eyes. At last examination, the corneal surface was covered by corneal-phenotype epithelium in 4 eyes, and the remaining 2 eyes had conjunctivalization. The cornea was optically clear in 3 eyes, with corrected visual acuity of 20/100 in these 3 eyes. Both eyes that developed conjunctivalization had massive fibrosis preoperatively and severe eyelid deformities. CONCLUSION: Although severe firework-related ocular surface injuries were difficult to treat, limbal stem cell transplantation combined with AMT enable some success in cosmetic and visual outcome. Management of eyelid abnormalities and ocular surface fibrosis seemed to be a key to success in visual rehabilitation.

Adolescent↗
PubMed2006

Ocular surface epithelial cells up-regulate HLA-G when expanded in vitro on amniotic membrane substrates.

PURPOSE: To study the modulation of immunoregulatory genes in ocular surface epithelial cells cultured on amniotic membrane (AM). METHODS: Microarray analysis was performed in a conjunctival epithelial cell line (CCL20.2) expanded on denuded AM. Among the genes that were upregulated by an AM substrate compared with collagen-coated dishes, the fetal nonclassic major histocompatibility complex molecule, HLA-G, was found to be the only immunoregulatory gene up-regulated by more than 2.5-fold. Because CCL20.2 is contaminated by HeLa cells, expression of HLA-G mRNA was confirmed in primary-cultured limbal (LE) and conjunctival epithelial (CE) cells by reverse transcriptase-polymerase chain reaction (RT-PCR), semiquantitative real-time PCR, immunocytochemistry, and Western blot analysis. A functional assay was performed using an HLA-G-transfected K-562 human erythroleukemia cell line. RESULTS: Freshly dissociated limbal epithelial cells express HLA-G mRNA; however, protein levels were low. Western blots and immunocytochemistry showed that both LE and CE cells upregulated the HLA-G protein when cultured on collagen-coated dishes and on AM. HLA-G mRNA levels were significantly higher in CE cultured on AM compared with collagen. Natural killer (NK) cell-induced cell lysis of an HLA class 1-negative K-562 human erythroleukemia cell line was slightly reduced when transfected with LE-derived HLA-G mRNA. CONCLUSION: CE and LE cells express functional HLA-G when expanded ex vivo, which may affect inflammation and immune reaction when transplanted to the ocular surface.

Amnion↗
PubMed2006

Association between meibomian gland changes and aging, sex, or tear function.

PURPOSE: To study changes in the lid margin and meibomian glands and their association with aging, sex, and tear function. METHODS: We examined 354 eyes in 177 subjects (76 men and 101 women; 21-93 years; mean age, 63.0 +/- 14.3 years) with no ocular symptoms or ocular surface disorders. Anatomic changes in the lid margin were studied using slit-lamp biomicroscopy. Meibomian gland function and morphology were evaluated on the basis of meibum expression and meibography, respectively. Tear function and ocular surface epithelium were assessed with the Schirmer test, by tear film break-up time, and with a fluorescein staining test. RESULTS: Eyes with abnormal lid margin anatomy, hyposecretion of meibum, and meibomian gland dropout were seen in 26 (7.3%), 46 (12.4%), and 68 eyes (18.6%), respectively, with a significant association between each finding and aging (P = <0.0001, 0.0498, and <0.0001, respectively). In patients < or =69 years of age, no significant association was found between meibomian gland-related findings and sex. However, a high incidence of abnormal lid margin and gland dropout was noted in men > or =70 years of age compared with women. No significant association was found between changes in the lid margin and meibomian glands and tear function in patients > or =40 years of age. CONCLUSION: Among symptom-free subjects, we found that changes in the lid margin and meibomian glands were closely related to aging. Among elderly subjects, changes in the anatomic lid margin and meibomian gland morphology were observed more frequently in men than in women. Tear function showed no association with either changes in the lid margin or function of the meibomian glands.

Adult↗
PubMed2006

Deep anterior lamellar keratoplasty.

PURPOSE OF REVIEW: Recent advances in surgical technique have promoted a paradigm shift in the surgical treatment of corneal disease. Penetrating keratoplasty is now being replaced by various types of lamellar techniques that aim to replace damaged tissue only, while maintaining healthy tissue intact. This review focuses on recent advances in deep anterior lamellar keratoplasty. RECENT FINDINGS: The concept of creating a deep lamellar bed for lamellar keratoplasty is not new, but exposing Descemet's membrane was a tedious, time consuming procedure. New techniques that use air and ophthalmic viscosurgical devices to directly expose Descemet's membrane have dramatically reduced surgery time, while improving the safety of performing surgery. The indications for deep anterior lamellar keratoplasty have expanded from keratoconus and hereditary dystrophies, to include severe ocular surface disease and cases following infection and corneal perforation. SUMMARY: Deep anterior lamellar keratoplasty can be considered as the first choice of surgery for a wide range of corneal disease, with bullous keratopathy as the only absolute contraindication.

Corneal Diseases↗
PubMed2006

Cytokeratin 15 can be used to identify the limbal phenotype in normal and diseased ocular surfaces.

PURPOSE: To elucidate the expression pattern of K15, K19, K14, and K12 in human and mouse ocular surface epithelium as putative markers of epithelial phenotype. METHODS: Immunohistochemical staining with specific antibodies for K15, K19, K14, and K12 was performed in human donor cornea tissue and normal ICR mouse corneas, with emphasis on localization of immunopositive cells. Immunohistochemistry was performed in a limbus-deficient mouse model as well as in clinical samples of pannus surgically removed from a thermal burn and a patient with Saltzmann's dystrophy. Staining patterns were classified as limited to the most basal layer (K(bas)), basal and suprabasal layers (K(bas-sup)), predominantly in suprabasal layers (K(sup)) and negative staining (K(-)). RESULTS: In human conjunctival epithelium, strong expression of K15 was observed in basal cells, whereas K19 was expressed in both basal and suprabasal layers (K15(bas)/K19(bas-sup)/K12(-)). Limbal epithelial cells were K15(bas-sup)/K19(bas-sup)/K12(sup), whereas epithelial cells in the central cornea were K15(-)/K19(bas-sup)/K12(bas-sup). In contrast, the mouse ocular surface demonstrated a different expression pattern of K15 and K19 than did the human tissue in the conjunctiva (K15(bas-sup)/K19(bas)/K12(-)) and the limbus (K15(bas-sup)/K19(bas)/K12(sup)). Neither K15 nor K19 was expressed in the central mouse cornea (K15(-)/K19(-)/K12(bas-sup)). Similar cytokeratin expression was observed in conjunctivalized corneas in mice and in surgically removed pannus tissue. CONCLUSIONS: Although the expression of K15 and K19 differ in humans and mice, specific staining patterns can be used to characterize the epithelial phenotype in normal and diseased ocular surface.

Animals↗
PubMed2005

Melanocytes in the corneal limbus interact with K19-positive basal epithelial cells.

The human corneal limbus is identified by the distinct features of the palisades of Vogt (POV), which contain pigment granules that are aligned with the microplicae of the epithelium. Although it is presumed that pigments are produced by melanocytes, the characterization of melanocytes in the limbus has not been clearly documented. We examined human limbal tissues by whole mounts and serial histological sections to localize epithelial cells containing melanin granules. Most of the pigmented cells observed by immunohistochemistry were K19 (+) cells in the basal limbal epithelium. A superimposed image revealed that melanin granules were oriented towards the apex of each K19 (+) cell, acting as a pigmented cap facing the ocular surface. Melanocytes were identified by MART1, an antigen specific to melanocyte-lineage cells. Melanocytes were shown to exist as sporadic cells with dendritic processes that extend to surrounding epithelial cells. Melanocytes were also found in light-pigmented donor tissue when visualized by the tyrosinase assay using the enzyme substrate DOPA. Since tyrosinase activity was not found in epithelial cells, the production of melanin is exclusively the role of melanocytes that comprised 5.3+/-2.7% of the total cells in cytospin samples (N=3). Melanocytes and K19 (+) epithelial cells may form a functional network similar to the melanin unit of the skin.

Aged↗
PubMed2005

Microkeratome-assisted phacoemulsification.

This study reports a technique in which phacoemulsification and intraocular lens (IOL) insertion are performed in conjunction with a microkeratome flap in a patient with ocular surface disease. Microkeratome-assisted phacoemulsification was performed in a 72-year-old woman with a history of trachoma during childhood. A 130 microm corneal flap was made using a microkeratome prior to phacoemulsification and IOL insertion. Lifting the flap during surgery allowed a clear view of the anterior chamber through the smooth lamellar interface created by the microkeratome blade. The flap was washed and repositioned without sutures at the end of surgery. There were no complications associated with the microkeratome flap following surgery. Visual acuity improved from hand motion to 20/200. Microkeratome-assisted phacoemulsification is a safe technique for cataract patients with diseases of the ocular surface.

Aged↗