Tissue engineering of corneal stroma with rabbit fibroblast precursors and gelatin hydrogels

PURPOSE

To isolate fibroblast precursors from rabbit corneal stroma using a sphere-forming assay, to engineer corneal stroma with the precursors and gelatin, and to establish the therapeutic application of precursors in a rabbit corneal stroma.

METHODS

In the in vitro study, a sphere-forming assay was performed to produce precursors from rabbit corneal stroma. Corneal stroma was engineered by cultivating precursors in porous gelatin for one week. In the in vivo study, the engineered corneal stromal sheet with precursors (precursor/gelatin group) or with fibroblasts (fibroblast /gelatin group) or without cells (gelatin group) was transplanted to a pocket of rabbit corneal stroma. Gene expression and extracellular matrix production were examined immunohistochemically in each group one week and four weeks after surgery.

RESULTS

In the in vitro study, cells in the spheres were BrdU-positive, and their progeny were keratocan-positive. The study also showed that the corneas transplanted with a porous gelatin sheet did not show any opacity four weeks after transplantation in any group. In the gelatin sheet of the precursor/gelatin group, a more intense expression of type I collagen was observed relative to the other two groups four weeks after the surgery.

CONCLUSIONS

Our findings demonstrate that the transplantation of fibroblast precursors combined with gelatin hydrogel into the corneal stroma is a possible treatment strategy for corneal stromal regeneration.

A novel isolation technique of progenitor cells in human corneal epithelium using non-tissue culture dishes

The existence of adult stem cells or progenitor cells in the human corneal epithelium (i.e., self-renewing squamous cells) has long been suggested, but these cells have not yet been isolated. Here we describe a novel isolation technique using non-tissue culture dishes to enrich progenitor cells, which are able to reconstitute a three-dimensional human corneal epithelial equivalent from single cells in serum-, feeder-, and bovine pituitary extract-free medium. These cells showed original tissue-committed differentiation, a high proliferative capacity, and limited self-renewal. Laminin-5 was measured by mass spectrometric analysis. Pretreatment of cells with anti-laminin-5 antibody demonstrated that laminin-5 was important in allowing corneal epithelial progenitor cells to adhere to non-tissue culture dishes. Hydrophilic tubes (used for cell collection throughout this study) are essential for efficient isolation of adherent corneal epithelial progenitor cells expressing laminin-5. These findings indicate that our new technique using non-tissue culture dishes allows the isolation of progenitor cells from human corneal limbal epithelium and that laminin-5 has a critical role in the adhesion of these cells.

Decellularizing corneal stroma using N2 gas

PURPOSE

To examine the efficacy of a novel method of decellularizing porcine corneal stroma using N(2) gas from liquid N(2) and the feasibility of using decellularized porcine corneal stroma in a corneal transplantation model in rabbits.

METHODS

Porcine corneas were placed in a tube, and N(2) gas from liquid N(2) was poured into the tube to freeze the corneas and make the inside of the tube hypoxic. After fastening the cap firmly, the tube was kept at room temperature for seven days, and the porcine corneas were examined histologically. A porcine corneal stromal disk treated with the aforementioned method was inserted into a pocket of rabbit corneal stroma and observed for six months.

RESULTS

Hoechst 33342 and hematoxylin and eosin staining both showed few cellular nuclei in the porcine corneal stroma incubated in N(2) gas for one week. A terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay showed many positively stained nuclei in the porcine corneal stroma incubated in N(2) gas for three days. The porcine corneal stroma that was decellularized and transplanted into a rabbit corneal stromal pocket remained clear for six months after transplantation.

CONCLUSIONS

This method using N(2) gas decellularizes corneal stroma without reducing corneal transparency.

[Treatment strategy for rejection-free corneal transplantation--transition from full-thickness corneal transplantation to corneal endothelium transplantation]

The avoidance of allograft rejection is the most critical factor for favorable surgical outcome after corneal transplantation. We report experimental data including distribution of white blood cells in human corneas for rejection-free corneal transplantation. We focused on leukocyte trafficking based on the immunological mechanism leading to allograft rejection in a mouse full-thickness corneal transplantation model. We identified two chemokine-receptors, CCR1 and CCR7 which are functionally relevant to the occurrence of allograft rejection. These chemokine receptors can be new targets for the suppression of allograft rejection after full-thickness corneal transplantation. In the human corneas, bone marrow-derived dendritic cells and monocyte-lineage cells reside constitutively in the normal epithelium and stroma, and may be associated with direct recognition of allo-antigen after corneal transplantation. We established a mouse model in which cultured allocorneal endothelium was transplanted onto a bullous keratopathy recipient cornea. During the follow-up period, the transplanted cultured allo-corneal endothelium did not show any sign of allograft rejection. Our findings demonstrated that a rejection-free mechanism is due not to suppression of immunity or to lack of response, but to failure to recognize the existence of resistance. Realization of the clinical application of cultured allo-corneal endothelium transplantation may be a shortcut to ideal rejection-free corneal transplantation.

Isolation and distribution of rabbit keratocyte precursors

PURPOSE

To isolate multipotent precursors from the rabbit corneal stroma and to compare the distribution and proliferative capacity of keratocyte precursors obtained from the central and peripheral regions of the corneal stroma.

METHODS

The rabbit corneal stroma was divided into a peripheral region (6.0-10.0 mm in diameter) and a central region (6.0 mm in diameter). A sphere-forming assay was then performed to isolate precursors from the stroma of each region. To promote differentiation, isolated sphere colonies were plated in wells with a medium containing fetal bovine serum. Expression of various markers by the sphere colonies and their progeny was examined using immunocytochemistry and/or reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS

The rate of primary sphere formation by cells from the peripheral stroma (51.4+/-10.1/10,000 cells) was significantly higher than by cells from the central stroma (35.9+/-3.0/10,000 cells; p=0.00021). Secondary sphere formation rate was significantly higher in the peripheral stroma (45.6+/-6.4/10,000 cells) than in the central stroma (33.4+/-2.1/10,000 cells; p=0.00002). Cells from the spheres were positive for CD34 and nestin. Their progeny showed a keratocyte-like spindle shape and expressed vimentin, alpha-smooth muscle actin, and two neural differentiation markers (microtubule-associated protein-2 and neuron-specific enolase). Expression of nestin and vimentin was confirmed by RT-PCR.

CONCLUSIONS

Our findings demonstrate that both the peripheral and central regions of the corneal stroma contain a significant number of precursors, but the peripheral stroma has more precursors with a stronger proliferative capacity than that of cells from the central stroma.

Transplantation of a sheet of human corneal endothelial cell in a rabbit model

PURPOSE

To develop a novel method for constructing a sheet of human corneal endothelial cells (HCECs) and examine the properties of the HCEC sheet.

METHODS

HCECs were cultured on a cell culture insert for a week; ethylenediamine tetraacetic acid was applied from the bottom of the cell culture insert to attenuate the attachment of HCECs. The sheet of HCECs was constructed by bluntly detaching the cell sheet with a spatula. HCEC cell sheets were placed on the posterior surface of excised rabbit corneal buttons and transplanted onto the corneal beds of donor rabbits. In two eyes from the HCEC sheet group, cultured HCECs were labeled with PKH26 to observe the localization of HCECs after transplantation.

RESULTS

Cultured HCECs could be bluntly detached en bloc from the bottom of a culture insert. Immunostaining for ZO-1, Na+, K+-ATPase, laminin, fibronectin, and type IV collagen was positive in the cell sheet. The average cell density in a HCEC sheet was 2,425 cells/mm(2). After HCEC sheet transplantation, corneal edema decreased much earlier in the HCEC group than in the control group. In the HCEC sheet group, the monolayer of continuous cells attached to the posterior surface of the transplanted rabbit cornea and the posterior surface of transplanted cornea was covered with PKH26-labeled cells. The average endothelial cell density in the HCEC sheet group seven days postoperatively was 2,244 cells/mm(2).

CONCLUSIONS

This technique for producing an HCEC sheet might be useful in regenerative medicine for the cornea and reconstruction of the corneal endothelium.

Characterization of Bone Marrow–Derived Cells in the Substantia Propria of the Human Conjunctiva

PURPOSE

To characterize the main population of bone marrow-derived cells (BMCs) in human normal subconjunctiva and make a comparison with BMCs in the corneal stroma and epithelium.

METHODS

Normal human donor corneas with attached conjunctiva were examined by fluorescence microscopy after single and double staining for multiple markers. CD68(+) cells were separated from the conjunctival tissues by using magnetic beads, and the expression of toll-like receptor (TLR) 2 and TLR4 was examined. Surface markers of CD68(+) cells were compared with those of BMCs from the corneal stroma and epithelium.

RESULTS

CD45(+) cells were detected in the substantia propria of the conjunctiva, and approximately 60% of these cells were CD68(+). All the CD68(+) cells expressed HLA-DR and CD14. CD68(+) cells isolated from conjunctival tissues expressed TLR2 and TLR4 on flow cytometry. BMCs in both the corneal stroma and the subconjunctiva expressed scavenger receptor CD163. Macrophage mannose receptor CD206 was expressed by BMCs in the substantia propria of the conjunctiva, but not by BMCs in the corneal stroma or epithelium.

CONCLUSIONS

These findings demonstrated that the main population of BMCs in the substantia propria of normal human conjunctiva is CD68(+)CD14(+)HLA-DR(+) cells. These BMCs express scavenger receptor, macrophage mannose receptor, TLR2, and TLR4 and may play a role in adaptive and innate immune responses in the human ocular surface. These cells are phenotypically different from the CD68(-)CD206(-) monocyte- lineage cells found in the corneal stroma and the CD11c(+)CD68(-)CD163(-)CD206(-) dendritic cells residing in the corneal epithelium.

Expression and function of toll-like receptor-3 and -9 in human corneal myofibroblasts

PURPOSE

To investigate the expression and function of toll-like receptor (TLR)-3 and -9 in corneal myofibroblasts.

METHODS

Two types of human keratocytes were used, which were freshly isolated keratocytes from donor corneas and cultured keratocytes. Expression of the mRNAs for various molecular markers was analyzed in these cells by RT-PCR, and TLR-2, -3, -4, and -9 mRNAs were also analyzed by RT-PCR. Expression of TLR-3 and -9 at the protein level was assessed by flow cytometry. In addition, an antibody array and ELISA were used to detect chemokines and cytokines in the supernatant of cultured keratocytes, with or without stimulation by poly inosine-polycytidylic acid (poly (I:C)) or CpG-DNA. Furthermore, a phagocytosis assay was performed to evaluate whether signaling via TLR-3 and -9 enhances phagocytosis.

RESULTS

Keratocytes cultured for three passages underwent differentiation into corneal myofibroblasts. TLR-3 and -9 were detected in corneal myofibroblasts at the mRNA and protein levels, but not in freshly isolated keratocytes. Stimulation of corneal myofibroblasts with poly (I:C) or CpG-DNA enhanced the production of IL-6, IL-8, GRO, ENA-78, and RANTES compared with that by untreated cells. Phagocytic activity of myofibroblasts was upregulated by signaling via TLR-3 and -9.

CONCLUSIONS

This is the first report on the in vitro expression and function of TLR-3 and -9 in corneal myofibroblasts. The findings suggest that the keratocyte phenotype determines the expression of TLR-3 and -9 and that corneal myofibroblasts may have an important role in bacterial and viral clearance.

Longitudinal Changes in Corneal Irregular Astigmatism and Visual Acuity in Eyes with Keratoconus

PURPOSE

To quantitatively investigate the time course of changes in corneal irregular astigmatism and their relation to best spectacle-corrected visual acuity (BSCVA) in eyes with keratoconus.

METHODS

Subjects were 47 patients (57 eyes) with keratoconus who had undergone videokeratography examinations at least twice, with an interval of 1 year or longer between each examination. By means of Fourier series harmonic analysis, topography data were separated into spherical component, regular astigmatism, asymmetry, and higher order irregularity.

RESULTS

In eyes that showed apparent progression on color-coded maps, the yearly rate of change was significantly positive for spherical component (P = 0.03) and higher order irregularity (P = 0.006). In eyes with apparent progression, the yearly change rate of BSCVA was significantly positive (P = 0.001), but not in the eyes without apparent progression (P = 0.1655). In eyes with progression on maps, the yearly change rate of BSCVA was significantly correlated with the change rate of higher order irregularity per year (r = 0.770, P = 0.0004).

CONCLUSIONS

The results indicated that progression of keratoconus is associated with deterioration of BSCVA, which is in turn significantly correlated with increases in corneal higher order irregularity.

Role of Macrophage Migration Inhibitory Factor in Corneal Neovascularization

PURPOSE

To determine the role of macrophage migration inhibitory factor (MIF) in inflammatory corneal neovascularization.

METHODS

Corneal neovascularization was induced by suturing 10-0 nylon 1 mm away from limbal vessel or limbal scraping after 0.15 M NaOH application in BALB/c mice. MIF expression was evaluated by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis, and immunohistochemistry. To investigate the function of MIF in inflammatory corneal neovascularization, the neovascularized area and number of infiltrating F4/80-positive cells (monocytes/macrophages) were compared between wild-type mice and homozygous MIF-deficient mice.

RESULTS

MIF mRNA and protein markedly increased in the neovascularized corneas compared with normal corneas by RT-PCR and Western blot analysis, respectively. MIF expression was upregulated immunohistochemically, not only in the corneal epithelium but also in the stromal infiltrating cells of neovascularized corneas. Neovascularized area in corneas of MIF(-/-) mice was significantly small compared with that in wild-type mice on day 7 after corneal suture and on day 14 after limbal scrape, and MIF(-/-) cornea had approximately 30% less neovascularized area than did wild-type cornea in both models. Neovascularized corneas in MIF-deficient mice had significantly fewer monocytes/macrophages than those in wild-type control mice.

CONCLUSIONS

These findings indicate that MIF, abundantly expressed in neovascularized corneas, has an angiogenic role in inflammatory corneal neovascularization and may be a therapeutic target for suppression of corneal neovascularization.

Autologous transplantation of conjunctival epithelial cells cultured on amniotic membrane in a rabbit model

PURPOSE

To evaluate the feasibility of autologous transplantation in a rabbit model of conjunctival epithelial cells cultured on amniotic membrane for ocular surface reconstruction.

METHODS

Limbal stem cell deficiency was induced in the right eyes of 30 rabbits. This was done by performing a lamellar keratectomy of the entire cornea and a complete removal of the limbus and conjunctiva, extending 5 mm outside the limbus. Autologous conjunctival specimens were obtained from the left eyes of ten of those rabbits and cultured for four weeks on denuded amniotic membrane. Cultured epithelium was examined by transmission electron microscopy. Four weeks after lamellar keratectomy, conjunctivalized corneal surfaces were excised and autologous cultured conjunctival epithelial sheets transplanted (Conj-AM group, n=10). The controls were rabbits that underwent corneal surface removal but not transplantation (No Transplantation group, n=10) and those that underwent corneal surface removal but received only amniotic membrane (AM Alone group, n=10). A neovascularization and corneal opacity scoring system was used to evaluate each eye in the two months after surgery.

RESULTS

Cultured conjunctival epithelium formed three to four layers on denuded amniotic membrane. Averaged scores of corneal neovascularization and corneal opacity two months after transplantation were significantly low in the Conj-AM group as compared with those in the AM and no transplantation groups.

CONCLUSIONS

Transplantation of autologous conjunctival epithelial cells cultured on amniotic membrane should prove an effective strategy for treating total limbal stem cell deficiency.

Corneal stromal and endothelial cell precursors

PURPOSE

To isolate precursors of human corneal stromal and endothelial cells in vitro and to compare the distribution of rabbit corneal endothelial cell precursors in the central and peripheral regions of the cornea.

METHODS

Sphere-forming cells were isolated from human corneal stromal and endothelial cells by a reaggregation-free neurosphere assay. To promote differentiation of the cells, the isolated sphere colonies were plated in wells with a medium containing fetal bovine serum. Expression of various proteins was examined in the sphere colonies and their progeny by immunocytochemistry and reverse-transcriptase polymerase chain reaction (RT-PCR). Corneal endothelium and Descemet membrane of rabbits were demarcated into peripheral (6.0-10.0 mm in diameter) and central (6.0 mm in diameter) regions. Precursor cells were isolated from these 2 regions by sphere-forming assay, and the number of sphere colonies and size of spheres were compared in the central and peripheral regions.

RESULTS

Human corneal stromal and endothelial cells formed sphere-shaped colonies that expressed mesenchymal and neural markers. The rate of sphere formation in the peripheral region of rabbit corneal endothelium was significantly higher than that in the central cornea.

CONCLUSION

Adult human corneal stroma contains precursor cells that have a strong propensity to differentiate into mesenchymal fibroblasts, but these cells can also differentiate into neuronal lineage. Adult human corneal endothelium contains precursors with a propensity to differentiate into corneal endothelial cells, but these cells can also produce neuronal and mesenchymal cell proteins. The peripheral endothelium of rabbit cornea contains more precursors than the central region.

Involvement of C-C chemokine ligand 2-CCR2 interaction in monocyte-lineage cell recruitment of normal human corneal stroma

Bone marrow-derived cells (BMCs) reside in the anterior stroma of the central and paracentral cornea, as well as all stromal layers of the peripheral cornea, in normal human eyes. We investigated the factors regulating the constitutive distribution of BMCs in normal human corneal stroma. Cultured human corneal keratocytes expressed several chemokines (growth-related oncogene/CXCL1-3, IL-8/CXCL8, and MCP-1/CCL2) in the Ab array study. CCR2 and CCR7 mRNAs were detected in BMCs by multiplex RT-PCR. Keratocytes/corneal epithelial cells and BMCs selected from normal human donor corneas by using magnetic beads expressed MCP-1/CCL2 and CCR2 protein, respectively. BMCs isolated from human corneal stroma showed a chemotactic response to MCP-1/CCL2 in the Boyden chamber assay. The chemotactic effect of keratocyte supernatant was inhibited by blockade of MCP-1/CCL2. This is the first work on constitutive expression of CCR2 by BMCs from the corneal stroma and MCP-1/CCL2 by keratocytes/epithelial cells. Our findings suggest that the interaction between MCP-1/CCL2 and CCR2 determines the distribution of constitutive BMCs in normal human corneal stroma.

Deletion of the chemokine receptor CCR1 prolongs corneal allograft survival

PURPOSE

Many corneal grafts undergo immune rejection, and current therapies are associated with many side effects. The purpose of this study was to identify critical chemokine pathways involved in generating the alloimmune response to corneal transplants.

METHODS

Orthotopic corneal transplantation was performed in fully mismatched strains. Cytokine and chemokine receptor gene expression was determined by the RNase protection assay. Knockout (KO) strains for chemokine-chemokine receptors that are upregulated after transplantation underwent corneal transplantation. Results derived from KO murine hosts were compared with cyclosporine (Cy) therapy. In addition to graft survival, graft infiltration, allospecific delayed-type hypersensitivity (DTH), and cytokine expression were compared among the recipient groups.

RESULTS

Initial experiments revealed gene upregulation of the chemokine receptors CCR1, -2, and -5 after corneal allorejection. Although CCR1 KO hosts showed a significant increase in graft survival compared with wild-type (WT) hosts, allografts in CCR5, CCR2/CCL3(MIP-1alpha), CXCR3, CXCL10/IP-10, and CCL3/MIP-1alpha KO mice did not show a significant improvement in graft survival. Further, CCR1 KO hosts showed a significantly higher survival rate than with systemic Cy therapy in WT hosts. Moreover, graft infiltration by leukocytes and gene expression of proinflammatory cytokines were reduced in CCR1 KO mice compared with both Cy treated and untreated WT mice, as was the induction of allospecific DTH.

CONCLUSIONS

These studies provide, for the first time, evidence that targeting of specific chemokine pathways can significantly promote survival of corneal transplants, and suggest that select deletion or suppression of CCR1 can be a useful therapeutic target in corneal transplant immunity.

Distribution of Precursors in Human Corneal Stromal Cells and Endothelial Cells

PURPOSE

We identified original tissue-committed precursors with limited self-renewal capacity from human corneal stromal (HCS) cells and human corneal endothelial (HCE) cells, then tried to determine the distribution and proliferative capacity of the precursors.

DESIGN

Experimental study.

PARTICIPANTS

Eighteen human corneas from donors 56 to 68 years old.

METHODS

Human corneal stromal cells were divided into groups based on distance from the center of the cornea: <6 mm (central), 6 to 8 mm (paracentral), and 8 to 10 mm (peripheral). Human corneal endothelial cells were separated into 2 groups: <7.5 mm (central) and 7.5 to 10 mm (peripheral) from the center. Each group was subjected to the sphere-forming assay using serum-free medium containing growth factors in floating culture. Sphere numbers and the proliferative capacity of spheres in adherent culture were compared among the groups.

MAIN OUTCOME MEASURES

Density and proliferative capacity of precursors from each area of HCS and HCE cells.

RESULTS

Primary spheres were isolated from all groups of HCS and HCE cells. The rate of primary sphere formation from peripheral HCS cells was higher than those of the other 2 groups, being 1.5-fold greater than in the paracentral cornea and 4-fold greater than in the central cornea. The rate of primary sphere formation by peripheral HCE cells was significantly higher than that by central HCE cells, being 4-fold greater than in the central cornea. There were no differences in the proliferative capacity of HCS and HCE cell spheres from the different areas after adherent culture.

CONCLUSIONS

All HCS and HCE cells contain a significant number of precursors, but the peripheral cells have a density of precursors higher than that of the central cells. Precursors from each area do not show differences of proliferative capacity. Our findings may in part explain changes after excimer laser treatment and may have implications for corneal transplantation procedures.

Retinal vasculitis and vitreous hemorrhage associated with mixed connective tissue disease: retinal vasculitis in MCTD

BACKGROUND

Retinal vasculitis associated with mixed connective tissue disease (MCTD) has rarely been reported in the literature. We describe a rare case of a patient with serious retinal vasculopathy and vitreous hemorrhages associated with MCTD.

CASE

A 53-year-old woman with MCTD who has had recurrent retinal vasculitis and vitreous hemorrhage in the right eye since 2000 presented with blurred vision in the right eye in April 2003. The best-corrected visual acuity was counting finger in the right eye. The patient was clinically diagnosed as having retinal and vitreous hemorrhages and retinal infarction. Prednisolone was administered orally in a daily dose of 20 mg.

RESULTS

The retinal and vitreous hemorrhage improved in 7 days. The best-corrected visual acuity improved to more than 20/20 on prednisolone alone.

CONCLUSION

MCTD can be associated with retinal vasculitis and vitreous hemorrhage which in our case responded well to systematic low doses of corticosteroid therapy.

Topical ocular drug delivery to inner ear disease and sinusitis

Oral steroids are the main therapy for sensorineural deafness. We present the rare case of a patient whose hearing loss associated with inflammation of the inner ear and chronic sinusitis were improved with topical steroid therapy. A 68-year-old male presented with scleritis in the left eye, inflammation of the inner ear and chronic sinusitis. He received oral prednisolone 10 mg/d. However, the oral prednisolone was discontinued due to severe side effects. Topical administration of 0.1% betamethasone sodium phosphate improved the scleritis and incidentally also relieved his symptoms of recurrent otitis and sinusitis after several days. Audiometry revealed recovered acoustic sensation in the right ear, from 50 dB to 20 dB, and in the left ear from 70 to 35 dB with 1,000 Hz. Topical ocular drug delivery of steroids may be effective for inner ear disease and sinusitis in patients with systemic side effects to oral steroids.

Isolation of Human Corneal Endothelial Cell Precursors and Construction of Cell Sheets by Precursors

PURPOSE

To review recently published experimental data on human corneal endothelium (CE) precursors.

METHODS

A sphere-forming assay was used for the isolation of human CE precursors from human donor corneas and cultured human CE. CE morphology derived from precursors was compared with that from cultured human CE.

RESULTS

Human CE from donor corneas formed primary and secondary sphere colonies and expressed neural and mesenchymal proteins. The progeny of these colonies had a human-CE-like hexagonal shape and showed transport activity, suggesting that the isolated spheres were indeed precursors of human CE. Similar precursors were isolated from cultured human CE, which provided further evidence that the sphere-forming assay facilitates the mass production of human CE precursors. Cultured human CE obtained in this manner had a regular hexagonal morphology in contrast to passaged, cultured human CE.

CONCLUSION

The sphere-forming assay may become a powerful tool for the regeneration of human CE by precursor injection and the construction of cultured CE sheets.

UV absorption in human oral mucosal epithelial sheets for ocular surface reconstruction

BACKGROUND

Ocular surface reconstruction with autologous oral mucosal epithelium has attracted attention as a novel treatment strategy that avoids allograft rejection.

OBJECTIVES

To evaluate the absorption of ultraviolet (UV) A or B irradiation by human oral mucosal epithelium cultured on human amniotic membrane.

METHODS

Human oral mucosal and limbal epithelial cells were co-cultured on amniotic membrane with inactivated 3T3 fibroblasts. The cell sheets were also subjected to UV-A (365 nm) or UV-B (302 nm) irradiation at energy levels ranging from 50 to 800 microW/cm2, and the UV absorption rate was measured with a UV irradiation meter.

RESULTS

Cultured oral mucosal epithelium had a structure with 3-5 layers of cells, consistent with the histological features of cultured corneal limbal epithelium after 4 weeks. The decrease in UV-A absorption of cultivated oral mucosal epithelium ranged from 25 to 36% of that for cultured corneal epithelium. The increase in UV-B absorption by cultured oral mucosal epithelium between 200 and 800 microW/cm2 was approximately 145% of that for cultured corneal limbal epithelium.

CONCLUSION

Our data demonstrated that cultured oral mucosal epithelium has low UV-A and high UV-B absorption capacity as compared with those of cultured corneal epithelium, suggesting that oral mucosal epithelium can compensate for UV absorption of corneal epithelium.

Comparison of Central Corneal Thickness Measurements by Rotating Scheimpflug Camera, Ultrasonic Pachymetry, and Scanning-Slit Corneal Topography

PURPOSE

To compare central corneal thickness measurements and their reproducibility when taken by a rotating Scheimpflug camera, ultrasonic pachymetry, and scanning-slit corneal topography/pachymetry.

DESIGN

Experimental study.

PARTICIPANTS

Seventy-four eyes of 64 subjects without ocular abnormalities other than cataract.

METHODS

Corneal thickness measurements were compared among the 3 methods in 54 eyes of 54 subjects. Two sets of measurements were repeated by a single examiner for each pachymetry in another 10 eyes of 5 subjects, and the intraexaminer repeatability was assessed as the absolute difference of the first and second measurements. Two experienced examiners took one measurement for each pachymetry in another 10 eyes of 5 subjects, and the interexaminer reproducibility was assessed as the absolute difference of the 2 measurements of the first and second examiners.

MAIN OUTCOME MEASURES

Central corneal thickness measurements by the 3 methods, absolute difference of the first and second measurements by a single examiner, absolute difference of the 2 measurements by 2 examiners, and relative amount of variation.

RESULTS

The average measurements of central corneal thickness by a rotating Scheimpflug camera, scanning-slit topography, and ultrasonic pachymetry were 538+/-31.3 microm, 541+/-40.7 microm, and 545+/-31.3 microm, respectively. There were no statistically significant differences in the measurement results among the 3 methods (P = 0.569, repeated-measures analysis of variance). There was a significant linear correlation between the rotating Scheimpflug camera and ultrasonic pachymetry (r = 0.908, P<0.0001), rotating Scheimpflug camera and scanning-slit topography (r = 0.930, P<0.0001), and ultrasonic pachymetry and scanning-slit topography (r = 0.887, P<0.0001). Ultrasonic pachymetry had the smallest intraexaminer variability, and scanning-slit topography had the largest intraexaminer variability among the 3 methods. There were similar variations in interexaminer reproducibility among the 3 methods.

CONCLUSIONS

Mean corneal thicknesses were comparable among rotating Scheimpflug camera, ultrasonic pachymetry, and scanning-slit topography with the acoustic equivalent correction factor. The measurements of the 3 instruments had significant linear correlations with one another, and all methods had highly satisfactory measurement repeatability.

Distribution of CESP-1 protein in the corneal endothelium and other tissues

PURPOSE

The gene expression profile of human corneal endothelium (CE) was established with the gene signature system. A novel gene, GS3582, was abundantly transcribed in the CE compared with other tissues according to a human gene expression database. This protein was designated corneal endothelium-specific protein (CESP)-1. The tissue distribution and subcellular localization of CESP-1 was assessed in humans and mice, to investigate its physiological function.

METHODS

Rabbit and mouse CESP-1 cDNAs were cloned, and a polyclonal anti-human CESP-1 antibody (Ab) and anti-mouse N- or C-terminal ovary-specific acidic protein (OSAP)-1 Ab were produced. CESP-1 expression was investigated in human and mouse corneas by Western blot and/or immunohistochemical analysis. The distribution of CESP-1 in human tissues was also examined by Western blot analysis. To identify the subcellular localization of CESP-1, cultured human CE was colabeled with anti-human CESP-1 Ab and anti-cytochrome c monoclonal Ab or anti-GRP78 monoclonal Ab for confocal microscopy.

RESULTS

The rabbit and mouse CESP-1 cDNA sequences contained an open reading frame coding 242 and 283 amino acids, respectively. Mouse CESP-1 was entirely consistent with mouse OSAP. Western blot analysis showed that CESP-1 was expressed in the human corneal epithelium, CE, cultured CE, brain, testis, and ovary. Mouse CESP-1 was also expressed in mouse corneal epithelium and CE with anti-mouse C- but not N-terminal OSAP Ab according to immunohistochemical analysis. Subcellular localization of CESP-1 to the mitochondria was demonstrated in cultured human CE. The N-terminal of CESP-1, possessing a mitochondrial targeting sequence, may be processed after the protein is imported into the mitochondria.

CONCLUSIONS

CESP-1 was distributed in the corneal epithelium, the CE and cultured human CE, as well as the brain, testis, and ovary. CESP-1 was localized in the mitochondria of cultured human CE. These findings may provide some clues about the physiological function of CESP-1.

Optic Disc and Retinal Nerve Fiber Layer Analysis With Scanning Laser Tomography After LASIK

PURPOSE

To examine whether LASIK induces changes in the optic disc and retinal nerve fiber layer using scanning laser tomography.

METHODS

Prospective, consecutive study of 53 myopic eyes in 38 patients (mean age: 35.7 +/- 10.4 years; range: 22 to 58 years). Preoperative average refractive error was -6.0 +/- 2.4 diopters (D) (spherical equivalent) (range: -2.0 to -10.0 D). Optic disc morphology and retinal nerve fiber layer thickness were evaluated with scanning laser tomography preoperatively and at 7 and 13 months postoperatively.

RESULTS

No statistically significant differences were noted between the pre- and postoperative optic disc and retinal nerve fiber layer measurements.

CONCLUSIONS

Our results suggest that transient extreme elevation of intraocular pressure during LASIK does not affect the optic disc morphology or retinal nerve fiber layer thickness in normal myopic eyes for at least 1 year after surgery.

Properties of corneas reconstructed with cultured human corneal endothelial cells and human corneal stroma

PURPOSE

To examine the properties of corneas tissue-engineered with cultured human corneal endothelial cells (HCEC) and human corneal stroma.

METHODS

Primary HCEC cultures were established from endothelial cell layer explants and propagated on culture dishes coated with bovine corneal endothelial extracellular matrix. A cell suspension of HCEC at the fifth passage was transferred onto human corneal stroma deprived of endothelial cells, and the corneas were gently centrifuged to enhance cell attachment. The cell density of the tissue-engineered corneas was examined after staining with alizarin red and trypan blue. The tissue-engineered corneas were histologically examined by light and electron microscopy. The pump function of the tissue-engineered corneas was measured using an Ussing chamber.

RESULTS

The mean endothelial cell density of four tissue-engineered corneas was 2380 +/- 264 cells/mm(2) (mean +/- SD). HCEC on the tissue-engineered corneas had a morphology similar to HCEC in vivo. The pump function parameters of the tissue-engineered corneas were 55%-75% of those of normal corneas.

CONCLUSIONS

HCEC on the tissue-engineered corneas have morphology and cellular density similar to HCEC in vivo, whereas the pump function of the tissue-engineered corneas was lower than in normal corneas.

Ocular manifestations of congenital insensitivity to pain with anhidrosis

PURPOSE

To describe ocular manifestations in Japanese patients with congenital insensitivity to pain with anhidrosis (CIPA), focusing particularly on the status of the ocular surface.

DESIGN

Observational case series.

METHODS

Eighteen patients with CIPA underwent applicable ophthalmologic examinations, including visual acuity, refraction, slit-lamp examination, fundus examination, tear breakup time, Schirmer 1 test, corneal sensitivity, and corneal topography.

RESULTS

Superficial punctate keratopathy (SPK) was observed at the interpalpebral area in 23 (64%) of 36 eyes. Corneal opacity was observed in three eyes (8.3%). Tear breakup time was below the lower limit of the normal range in all examined eyes, and the value of Schirmer 1 test was above the lower limit of the normal range in most of the examined eyes.

CONCLUSIONS

Superficial punctate keratopathy is observed in most cases of CIPA, which might predispose patients to corneal infection. Investigation of dry eye in patients with CIPA will provide unique opportunities to explore the critical roles of the autonomic sympathetic nervous system as well as the sensory nervous system in the physiology of tear production.

Allergens in Japanese patients with allergic conjunctivitis in autumn

PURPOSE

The purpose of the current study is to evaluate the relation between various specific class E immunoglobulins (IgE) in the serum and allergic conjunctivitis in autumn.

METHODS

Total IgE and specific IgE to 12 inhalant allergens were measured using the CAP system in 32 patients with allergic conjunctivitis in spring (spring group), 27 patients with allergic conjunctivitis in autumn (autumn group), and 40 healthy volunteers (control group).

RESULTS

Specific IgE levels caused by house dust, Dermatophagoides pteronyssinus, and orchard grass were higher in the autumn group than in the spring group. The highest positivity rate for a specific allergen was 51.9% for house dust, followed by D. pteronyssinus(48.1%) in the autumn group, while the highest rate was 68.8 % for cedar pollen, followed by cypress pollen (59.4%) in the spring group. Correlation analysis showed that house dust was significantly correlated with animal epithelia, D. pteronyssinus, acarus, and Alternaria tenuis in the autumn group (P<0.001).

CONCLUSIONS

These results suggest that house dust is the main cause of allergic conjunctivitis during autumn. In spring, cypress pollen is the largest cause of allergic conjunctivitis, while indoor allergens such as house dust, animal epithelia, D. pteronyssinus, and acarus are not causative allergens in Japan.

Bone marrow-derived cells in mouse and human cornea

Recently published experimental data on the distribution of bone marrow (BM)-derived cells in human and mouse corneas in comparison with in human skin/oral mucosa are reviewed. In mouse corneal epithelium, major histocompatibility complex (MHC) class II-negative dendritic cells (DC) are present. Immature MHC class II-negative and mature MHC class II-positive DC are present in the center and periphery of the anterior corneal stroma, respectively. Monocyte (Mo)/macrophage (MPhi) lineage cells including the MPhi marker F4/80-expressing cells reside in the posterior stroma. In human cornea, MHC class II (HLA-DR)-positive immature myeloid DC (CD11cCD16, CD11cCD16, and CD11cCD1c) and Mo/MPhi lineage cells are detectable in the corneal epithelium and stroma, respectively. Distribution of Mo/MPhi lineage cells (HLA.DRCD11bCD11cCD14) is predominant in the anterior stroma of the central cornea and all layers of the peripheral cornea. Both the phenotypes and distribution pattern of these cells in human cornea are different from those of human skin and nasal mucosa. These findings suggest that BM-derived cells in normal human cornea are present in situ in preparation for foreign antigen and pathogens and have critical roles in innate and acquired immunity of the ocular surface.

Bone Marrow–Derived Cells in Normal Human Corneal Stroma

OBJECTIVE

To examine the normal human corneal stroma for the presence of bone marrow-derived cells.

METHODS

Thirty-four corneas from donors aged 56 to 71 years were used. The stroma of the donor corneas was examined immunohistochemically by fluorescent microscopy. CD45-positive and -negative cells were separated from collagenase-digested stroma by magnetic beads, and the expression of toll-like receptor 4 was analyzed.

RESULTS

CD45-positive cells were mainly found in the anterior stroma of the central and paracentral cornea as well as all stromal layers of the peripheral cornea (n = 5). These cells uniformly expressed CD11b, CD11c, CD14, and HLA-DR antigen but not CD3, CD19, CD56, or CD66, indicative of bone marrow-derived monocyte lineage cells, which can include monocytes, macrophages, or dendritic cells. CD45-positive cells isolated with magnetic beads accounted for 6.0% of total stromal cells (n = 20). Stromal CD45-positive cells, but not CD45-negative cells, expressed toll-like receptor 4 by flow cytometry and reverse-transcriptase polymerase chain reaction.

CONCLUSION

Our findings demonstrate that DR antigen-positive bone marrow-derived monocyte lineage cells exist in the anterior and peripheral posterior stroma of normal human cornea. Clinical Relevance These cells may play a role in the innate and adaptive immune responses in the human cornea.

Distinct Populations of Dendritic Cells in the Normal Human Donor Corneal Epithelium

PURPOSE

To characterize dendritic cells (DC) in normal human corneal epithelium.

METHODS

Normal human donor corneal epithelium was examined by fluorescence microscopy with single and double staining for multiple markers. Morphologic studies were also performed by confocal microscopy. HLA-DRa, CD1c, and CD16 mRNA expression in the corneal epithelium was examined by RT-PCR. CD45+ cells were separated from the corneal epithelium with magnetic beads and then were stimulated with TNF-alpha and lipopolysaccharide in vitro.

RESULTS

CD45+ cells were mainly located in the basal-cell layer of the corneal epithelium and partly in the wing/surface layers. CD45-positive cell numbers were significantly higher in the peripheral cornea (3-6 mm from the center) than in the central cornea (0-3 mm from the center). All these cells expressed HLA-DR and CD11c but not CD3, CD11b, CD14, CD19, CD56, or CD66, suggesting that these were bone marrow-derived myeloid DC. Some DR+CD11c+ DCs from the periphery expressed CD1c and CD16. HLA-DRa, CD1c, and CD16 mRNAs were detected in normal corneal epithelium. These CD11c+ DCs did not express CD123, CD1a, DC marker (CMRF56), CD40, CD80, or CD86. When CD45+ cells were isolated from the corneal epithelium by magnetic cell sorting, CD40 and CD86 expression were detected after in vitro stimulation with TNF-alpha and lipopolysaccharide.

CONCLUSIONS

These findings demonstrate that normal human corneal epithelium contains at least three DC phenotypes, with HLA-DR+ myeloid lineage CD11c+CD16- DCs as the main population plus a small number of CD11c+CD16+ DCs and CD11c+CD1c+ DCs. These cells can be discriminated from bone marrow-derived cells in the human corneal stroma.

Glutamic Acid Decarboxylase Autoantibody Prevalence and Association with HLA Genotype in Patients with Younger-Onset Type 1 Diabetes and Proliferative Diabetic Retinopathy

OBJECTIVE

To investigate the relationship of HLA status and autoantibodies to glutamic acid decarboxylase (GAD) in proliferative diabetic retinopathy (PDR) to assess the role of autoimmunity and genetic markers in retinopathy.

DESIGN

Retrospective, nonrandomized, comparative study.

PARTICIPANTS

Patients who had suffered from type 1 diabetes for >10 years and who had been first diagnosed as diabetic under 30 years of age were studied. They were classified into 3 groups: 20 patients with diabetes and PDR (PDR group), 22 patients who had diabetes and severe nonproliferative diabetic retinopathy (SNPDR group), and 25 patients who had diabetes with no diabetic retinopathy (non-DR group).

METHODS

Blood was collected, and the relationship between HLA status and GAD autoantibody positivity in diabetic retinopathy was investigated in a cross-sectional study.

MAIN OUTCOME MEASURES

Human leukocyte antigen status and GAD autoantibody positivity.

RESULTS

The highest positive rate of GAD autoantibody was 56.0% in the non-DR group, followed by the SNPDR group (40.1%) and the PDR group (15.0%). The frequencies of the HLA-DQ4 and -DR4/-DQ4 haplotypes were significantly higher in the PDR group (75.0% and 65%, respectively) than in the SNPDR group (40.9% and 31.8%) or the non-DR group (40.0% and 28.0%) (P = 0.035 and P = 0.026, respectively). The prevalence of GAD antibodies was lower in patients with the HLA-DR4 and HLA-DQ4 alleles and -DR4/-DQ4 haplotype frequencies in the PDR group (P = 0.018, P = 0.0088, and P = 0.0031, respectively).

CONCLUSIONS

We found that the existence of GAD antibodies is inversely related and HLA status is directly related to the stage or severity of retinopathy.

Corneal Endothelial Cell Protection With Viscoat and Healon or Healon Alone During Penetrating Keratoplasty

PURPOSE

To determine the influence of dispersive ophthalmic viscosurgical products (OVPs) on corneal endothelial cell (CEC) density during penetrating keratoplasty (PKP) and on the postoperative intraocular pressure (IOP).

METHODS

In 117 eyes of 113 patients, PKP was performed by a single surgeon from April 1, 1998 to April 30, 2002. Loss of CECs and postoperative IOP were evaluated retrospectively after use of Viscoat (sodium hyaluronate 3.0%, chondroitin sulfate 4.0%) plus Healon (sodium hyaluronate 1.0%) (Viscoat/Healon group) or Healon alone (Healon group) during surgery.

RESULTS

The average CEC loss was 14.6 +/- 15.5% and 9.0 +/- 10.5% at 1 month, 18.1 +/- 14.6% and 10.1 +/- 7.3% at 3 months, 20.1 +/- 16.3% and 12.2 +/- 10.9% at 6 months, and 31.7 +/- 21.4% and 18.1 +/- 15.5% at 12 months in the Healon (n = 74) and Viscoat/Healon (n = 43) groups, respectively. Patients were stratified into groups with corneal leukoma (n = 61) or bullous keratopathy (n = 56). Loss of CECs was significantly smaller in the Viscoat/Healon group compared with the Healon group irrespective of whether patients had corneal leukoma or bullous keratopathy at 3, 6, and 12 months postoperatively. There was no significant difference of postoperative IOP between the Healon and Viscoat/Healon groups over 12 months of follow-up.

CONCLUSION

These results suggest that the addition of Viscoat to Healon decreases CEC loss during PKP and does not affect postoperative IOP.

Intraocular pressure measurement over amniotic membrane patch in human subjects

PURPOSE

To investigate the accuracy of intraocular pressure (IOP) measurement over amniotic membrane patching on human ocular surface using Tono-Pen tonometry.

METHODS

The IOP of 28 normal eyes in 14 volunteers (mean age, 27.6 years; range, 25-34) was measured by a handy applanation tonometer and the Tono-Pen XL. Then, a single layer of amniotic membrane (approximately 50 microm) was placed onto the corneal surface of the volunteers and the IOP was again measured using the Tono-Pen XL.

RESULTS

The average IOP using handy applanation tonometry and the Tono-Pen was 14.3 +/- 2.1 and 14.3 +/- 2.4 mm Hg, respectively. In the presence of amniotic membrane, the average IOP was not significantly overestimated (14.7 +/- 2.6 mm Hg). The bias between handy applanation tonometry or the Tono-Pen XL without amniotic membrane and the Tono-Pen XL with amniotic membrane was only -0.40 and -0.18 mm Hg, respectively.

CONCLUSIONS

The Tono-Pen XL is accurate and useful for IOP monitoring even in eyes with amniotic membrane patching.

Management of subconjunctival haematoma by tissue plasminogen activator

A patient with subconjunctival haematoma related to enterovirus 70 who was treated with tissue plasminogen activator (tPA) is reported. A 46-year-old man developed a severe subconjunctival haematoma and discharge in the left eye. Investigations, including coagulation tests, showed no abnormalities apart from a high-serum antibody titre for enterovirus 70. The polymerase chain reaction demonstrated enterovirus 70 DNA in resected conjunctival tissue, leading to a diagnosis of acute haemorrhagic conjunctivitis. The left eye was treated with a single subconjunctival injection of tPA (16 000 IU) and the subconjunctival haematoma resolved completely after 3 days. Severe subconjunctival haematoma can occur in patients with acute haemorrhagic conjunctivitis due to enterovirus 70. Subconjunctival injection of tPA may be useful for the treatment of severe subconjunctival haematoma.

Comparison of rabbit corneal endothelial cell precursors in the central and peripheral cornea

PURPOSE

To compare the distribution and self-renewal capacity of rabbit corneal endothelial cell precursors in the central and peripheral regions of the cornea.

METHODS

The corneal endothelium (CE) and Descemet's membrane of New Zealand White rabbit corneas were divided into a peripheral region (6.0-10.0 mm in diameter) and a central region (6.0 mm in diameter). Then a sphere-forming assay was performed to isolate precursors from the CE of each region. Numbers of primary and secondary sphere colonies and sizes of primary spheres were compared between the central and peripheral regions.

RESULTS

Primary spheres were isolated from the peripheral and the central regions of the CE. The rate of primary sphere formation in the peripheral region (34.4 +/- 10.4/10,000 cells) was significantly higher than in the central cornea (26.8 +/- 6.6/10,000 cells; P = 0.0042), but there was no significant difference in the size of primary spheres between the two regions. Self-renewal capacity was higher in the peripheral region than in the central region, as evidenced by a significantly higher secondary sphere formation rate for cells from the periphery (39.0 +/- 8.8/10,000 cells) compared with that for cells from the central region (25.4 +/- 4.2/10,000 cells; P = 0.00028).

CONCLUSIONS

These findings demonstrate that peripheral and central rabbit corneal epithelia contain a significant number of precursors but that the peripheral endothelium contains more precursors and has a stronger self-renewal capacity than the central region.

Treatment of rabbit bullous keratopathy with precursors derived from cultured human corneal endothelium

PURPOSE

To establish a method for the mass production of human corneal endothelium (HCE) precursors and the therapeutic application of these cells in a rabbit CE-deficiency model.

METHODS

A sphere-forming assay was performed to produce precursors from cultured HCE. Various marker expressions were examined in the sphere colonies, and their progenies by immunocytochemistry and reverse transcription-polymerase chain reaction (RT-PCR). The transport activity of the sphere-derived cell sheet was evaluated by the Ussing chamber system. DiI-labeled precursors obtained from cultured HCE were injected the anterior chamber of the eye in a rabbit CE-deficiency model, and the eye-down position was maintained for 24 hours for attachment to Descemet's membrane (sphere eye-down group). The sphere eye-down and control groups, observed for 28 days after surgery, underwent histologic and fluorescence microscopic examinations.

RESULTS

Cultured HCE formed primary and secondary sphere colonies. The spheres expressed alpha-smooth muscle actin and nestin, and progeny expressed alpha-smooth muscle actin, confirmed by RT-PCR. The progeny showed an HCE-like hexagonal shape, were confluent, and had adequate transport activity. Mean corneal thickness in the sphere eye-down group was significantly less than in the other control groups 14, 21, and 28 days (P < 0.006) after surgery. The HCE-like hexagonal cells detected on the Descemet's membrane are DiI-positive in the sphere eye-down group.

CONCLUSIONS

The findings demonstrate that culture of HCE can promote mass production of HCE precursors, determined by sphere-forming assay. Injection of precursors derived from cultured HCE into the anterior chamber is an effective treatment strategy for CE deficiency in a rabbit model.

Sphere Therapy for Corneal Endothelium Deficiency in a Rabbit Model

PURPOSE

To isolate precursor cells derived from rabbit corneal endothelium (CE) and to use them for the treatment of CE deficiency in a rabbit model.

METHODS

A sphere-forming assay was performed to isolate precursor cells from rabbit CE. Immunocytochemistry was used to examine marker expressions of neural and mesenchymal cells in the sphere colonies and their progenies. The pump function of the CE sheet was evaluated by measurement of the potential difference and short circuit current. Precursors obtained from rabbit CE by a sphere-forming assay were injected into the anterior chamber of the eye, after which an eye-down (i.e., CE up) position was maintained for 24 hours to allow attachment by gravitation (sphere eye-down group). The sphere eye-down and control groups, observed for 28 days after surgery, underwent histologic and fluorescence microscopic examinations.

RESULTS

Rabbit CE formed primary and secondary sphere colonies. The progeny expressed alpha-smooth muscle actin, nestin, and neural markers and showed a CE-like hexagonal shape and adequate transport activity. Mean corneal thickness in the sphere eye-down group was significantly less than in the other control groups 3, 7, 14, 21, and 28 days (P < 0.05) after surgery. CE-like hexagonal cells were detected on Descemet's membrane, and corneal edema was substantially suppressed. DiI-labeled cells were spread over the rear corneal surface in the sphere eye-down group only.

CONCLUSIONS

Precursors from rabbit CE were isolated by a sphere-forming assay. Rabbit CE-derived sphere therapy is an effective treatment in a rabbit CE deficiency model.

Early ocular chemokine gene expression and leukocyte infiltration after high-risk corneal transplantation

PURPOSE

To determine the differential gene expression of chemokine species and leukocyte infiltration of grafts in the early pre-rejection postoperative period after high-risk (HR) compared to normal-risk (NR) corneal transplantation.

METHODS

Fully mismatched and syngeneic corneal grafts were performed in NR (avascular) and HR (vascularized) recipient beds of BALB/c murine hosts. Gene expression levels of a panel of chemokines were determined by a multiprobe ribonuclease protection assay system. The profiles of infiltrating cells into the corneal grafts at the same times were determined immunohistochemically.

RESULTS

Compared to NR transplantation, HR eyes exhibited significantly higher mRNA levels for macrophage inflammatory protein (MIP)-2 and monocyte chemotactic protein-1 (MCP-1) on day 1, and for eotaxin on days 1 and 3 after transplantation. By day 6 after transplantation, still well before graft rejection, significantly higher levels of RANTES, eotaxin, MIP-1alpha, MIP-1beta, MIP-2, and MCP-1 were detected in HR eyes. The overexpression of MIPs in HR eyes correlated with a significant increase in the number of infiltrating macrophages (p<0.01), and neutrophils (p<0.05) in HR compared to NR recipients. Low levels of eosinophil and mast cell infiltration were observed in all grafts, with a modest increase in mast cell infiltration (p<0.05) in HR compared to NR grafts.

CONCLUSIONS

These results suggest that increased expression of gene products for select chemokines, in particular those that mediate recruitment of innate immune cells, in the early period after HR corneal transplantation is related to the enhanced leukocytic infiltration of grafts observed in HR keratoplasty.

Human corneal endothelial cell precursors isolated by sphere-forming assay

PURPOSE

To isolate precursors of human corneal endothelial cells (HCECs) in vitro.

METHODS

HCECs were subjected to a sphere-forming assay in which spheres floated in serum-free medium containing growth factors. To promote differentiation, the isolated sphere colonies were plated in dishes coated with poly-L-lysine (PLL)/laminin or fetal bovine endothelium extracellular matrix. Marker expression of neural and mesenchymal cells was examined in the sphere colonies and their progenies by immunocytochemistry and/or reverse transcription-polymerase chain reaction (RT-PCR). Adherent differentiated cells from the sphere colonies were evaluated morphologically and functionally.

RESULTS

HCECs formed primary and secondary spherical colonies, as shown by sphere-forming assay in vitro. The colonies expressed nestin, beta3-tublin, glial fibrillary acidic protein, and alpha-smooth muscle actin on immunocytochemistry. The progeny, proliferating on extracellular matrix derived from bovine corneal endothelium, but not on PLL/laminin-coated and noncoated dishes, expressed nestin and beta3-tublin. These markers were confirmed by RT-PCR. Adherent differentiated cells from the sphere colonies had an HCEC-like hexagonal shape and satisfactory transport activity that is essential in HCECs.

CONCLUSIONS

These findings indicate that the HCEC contains precursor cells with a propensity to differentiate into HCECs and that these cells can also produce neuronal and mesenchymal cell proteins.

Sphere formation and expression of neural proteins by human corneal stromal cells in vitro

PURPOSE

To demonstrate the presence of corneal stromal precursors that express neural markers in vitro.

METHODS

To isolate sphere-forming cells, human corneal stromal cells were subjected to a reaggregation-free neurosphere assay in medium containing methylcellulose gel matrix. To promote differentiation, the isolated sphere colonies were plated in wells with medium containing fetal bovine serum. Expression of nestin, vimentin, keratocan, alpha-smooth muscle actin (alphaSMA), beta-III tubulin, neurofilament M (NFM), and glial fibrillary acidic protein (GFAP) was examined in the sphere colonies and their progeny (i.e., cells migrated from sphere colonies), by immunocytochemistry and/or reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Human corneal stromal cells formed sphere colonies that had no self-renewal capability. The frequency of sphere-forming cells was 1.5% +/- 0.1% (range, 1.3%-1.6%). Most of the cells within these colonies expressed nestin and vimentin, whereas some expressed beta-III tubulin, NFM, GFAP, and alphaSMA by immunocytochemistry. Ninety-one percent and 89% of the progeny expressed vimentin and alphaSMA, respectively, whereas nestin was undetectable. beta-III tubulin-, NFM-, and GFAP-positive cells were detected in the progeny at the frequency of 7.2%, 0.9%, and 0.5%, respectively. Semiquantitative RT-PCR showed that nestin, NFM, GFAP, and keratocan gene expression was higher in the sphere colonies, whereas vimentin and alphaSMA expression increased in the progeny.

CONCLUSIONS

Adult human corneal stroma contains precursor cells that express neural markers.

Evidence that T-Helper Type 2 Cell-Derived Cytokines and Eosinophils Contribute to Acute Rejection of Orthotopic Corneal Xenografts in Mice

BACKGROUND

Because guinea pig corneal xenografts are rejected acutely (within 16 days) in mouse eyes by a T-cell-dependent mechanism, the authors wished to determine the functional phenotype of CD4+ effector T cells.

METHODS

Orthotopic corneal xenotransplantation was performed from strain 13 guinea pigs to BALB/c mice. Grafted eyes were removed at specified times and examined histologically or subjected to cytokine and chemokine mRNA analysis using a multi-probe ribonuclease protection assay. Draining cervical lymph node cells were harvested at specified times and stimulated in vitro with x-irradiated strain 13 guinea pig spleen cells. Supernatants were assayed by enzyme-linked immunosorbent assay for content of interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-5, and IL-10 and cells were used for mRNA analysis.

RESULTS

Rejected corneal xenografts were heavily infiltrated with polymorphonuclear leukocytes, the majority of which were eosinophils. These eyes contained mRNA for IL-4, IL-6, IL-10, IL-13, IL-15, and IFN-gamma. When stimulated with guinea pig spleen cells, T cells from draining cervical lymph nodes secreted primarily IL-4, IL-5, IL-10, and IFN-gamma. Eotaxin was overexpressed in eyes with rejected corneal xenografts.

CONCLUSIONS

Acute rejection of corneal xenografts in mice is mediated by T cells that display a mixed T-helper (Th) type 2/Th1 phenotype and secrete eotaxin, an eosinophil chemoattractant. Eosinophil-dependent xenograft rejection bears similarities to immune elimination of parasites.

CCR5 chemokine receptor mediates recruitment of MHC class II-positive Langerhans cells in the mouse corneal epithelium

PURPOSE

To characterize the chemokines and chemokine receptors that mediate the effect of proinflammatory cytokines, interleukin (IL)-1 and tumor necrosis factor (TNF)-alpha, on the recruitment of MHC class II(+) Langerhans cells (LCs) in the corneal epithelium.

METHODS

A standard model for corneal LC recruitment, application of cautery to the central corneal surface was used, and the differential gene expression levels of a panel of chemokines and chemokine receptors were determined by RNase protection assay. Chemokine receptor-knockout mice were used to evaluate the recruitment of MHC class II(+) LCs to the corneal epithelium. To determine the sensitivity of selected chemokines to IL-1 and TNF-alpha stimulation, the chemokine gene expression pattern was analyzed after blockade of IL-1 and TNF receptors.

RESULTS

CCR1, -2, and -5 were overexpressed in corneas after cauterization. Topical administration of soluble TNF receptor I and IL-1 receptor antagonist, which abrogated corneal LC recruitment, significantly suppressed the gene transcription levels of the ligands of CCR1 and/or -5, regulated on activation normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta. The recruitment of major histocompatibility complex (MHC) class II(+) LC was significantly suppressed in CCR5(-/-) mice and blockade of RANTES and MIP-1beta, but not in CCR1(-/-), CCR2(-/-)/MIP-1alpha(-/-), or MIP-1alpha(-/-) mice. The evaluation of epithelial CD11c(+) LC cells by confocal microscopy revealed coexpression for CCR5 primarily among B7(-) (CD80(-)/CD86(-)) subsets of these LCs but not among the mature B7(+) subsets of CD11c(+) LCs.

CONCLUSIONS

These data suggest that CCR5 plays a critical role in mediating recruitment and mobilization of MHC class II(+) LCs into the corneal epithelium. Targeting CCR5 and its ligands may be a new strategy for modulating immunity.

A randomised, placebo controlled clinical trial of the aldose reductase inhibitor CT-112 as management of corneal epithelial disorders in diabetic patients

AIM

To evaluate the efficacy of topical aldose reductase inhibitor CT-112 (5-[3-ethoxy-4-pentyloxyphenyl]-2,4-thiazolidinedione) on corneal epithelial barrier function in diabetic patients.

METHODS

This was a prospective, randomised, double masked placebo controlled study. 34 eyes of 34 diabetic patients were randomly assigned treatment with 0.25% eye drops of CT-112 (n = 22) or a placebo (n = 12) four times a day for 8 weeks. Corneal fluorescein staining and corneal sensation were examined before treatment as well as 4 and 8 weeks after administration. Corneal epithelial permeability to fluorescence was measured with an anterior fluorophotometer.

RESULTS

Average scores of superficial punctate keratopathy and corneal sensitivity did not differ significantly between the two groups at any time. Whereas average fluorescein concentrations did not differ significantly for the CT-112 and placebo groups before treatment, they did differ significantly 4 and 8 weeks after treatment (4 weeks, p = 0.0327; 8 weeks, p = 0.0143).

CONCLUSION

The topical aldose reductase inhibitor, CT-112 improves the corneal epithelial barrier function in diabetic patients.

Long-term outcome of iron-endocytosing cultured corneal endothelial cell transplantation with magnetic attraction

The long-term efficacy and safety of transplanting iron-endocytosing cultured corneal endothelial cells (CECs) with magnetic attraction were evaluated. Rabbit corneas were subjected to cryo-injury to detach CECs. Cultured rabbit CECs (RCEC) were exposed to spherical iron powder and then injected into the anterior chamber, after which a neogium magnet was fixed on the eyelid for 24 hr to attract the cells to Descemet's membrane (RCEC-iron group, n=4). An RCEC group (cryo-injury and injection of normal cultured RCEC, n=4) and a Cryo group (cryo-injury without injection of RCEC, n=4) served as controls. Intraocular pressure was measured for 12 months after surgery. Corneal findings on slit lamp biomicroscopy, RCEC density, the electro-retinogram (ERG), and residual iron in the ocular tissues were evaluated at final assessment. Intraocular pressure did not increase in any group throughout 12 months of observation. At the final assessment, the average corneal edema score of the RCEC-iron group was significantly lower than that of the RCEC or Cryo groups (p=0.021). The average CEC density of the RCEC-iron group was 2581+/-230 cells mm(-2) (mean+/-SD), whereas no CECs were observed on the inner surface of the central cornea in the RCEC and Cryo groups. No significant differences of the ERG (a- and b-wave amplitudes, and b-wave/a-wave ratio) were detected among the groups. Iron powder was not detected by Berlin blue staining in the ocular tissues of the RCEC-iron group. Apoptotic cells were not observed in the endothelium by terminal transferase-mediated nick-end labeling. Transplanted iron-endocytosing RCEC remained viable for 12 months after surgery. There were no detectable ocular complications after the transplantation of iron-endocytosing cultured RCEC. Magnetic attachment of iron-endocytosing CECs can be an effective and safe method for corneal endothelial repair.

Chemokine receptor gene expression in giant papillae of atopic keratoconjunctivitis

PURPOSE

Major chemokine receptors in the giant papillae of atopic keratoconjunctivitis (AKC) have yet to be determined. We evaluated chemokine receptor genes and their ligand expressions in upper tarsal conjunctival giant papillae of AKC with atopic dermatitis and/or asthma.

METHODS

CC, CXC, and CX3C chemokine receptor (R) gene expression levels in giant papillae of five clinically active AKC patients and in three age matched non-allergic control conjunctiva were measured with a multi-probe ribonuclease protection assay (RPA) system. The ligands of abundant chemokine receptors in the giant papillae were examined by immunohistochemistry or reverse transcription-polymerase chain reaction. Interleukin (IL)-4 and IL-13 gene expression levels were measured with RPA. Ligand expression in cultured human conjunctival fibroblasts was examined by reverse transcription-polymerase chain reaction.

RESULTS

High CXCR4 and CCR4 gene expression levels were detected in the giant papillae of all (CXCR4) and four out of five (CCR4) patients. As a CCR4-ligand, thymus and activation regulated cytokine (TARC/CCL17) rather than macrophage derived chemokine (MDC/CCL22), was predominant immunohistochemicaly in the giant papillae. Giant papillae with high CCR4 gene expression levels showed high IL-4 and IL-13 expression. Cultured human conjunctival fibroblasts express stromal cell derived factor-1 (SDF-1/CXCL12) in vitro.

CONCLUSIONS

CXCR4 and CCR4 are the major chemokine receptor genes expressed in the giant papillae of AKC with atopic dermatitis and/or asthma. Our findings suggest a role for CXCR4 and CCR4 in the formation of giant papillae.

Vasovagal syncope evoked by needle phobia when inserting a contact lens*

PURPOSE

To report a patient who fell unconscious because of vasovagal syncope evoked by needle phobia when he tried to wear contact lenses.

CASE REPORTS

A 16-year-old healthy boy had sometimes experienced dizziness when looking at the tips of pens. When he put his finger and the lens close to his eye to insert a soft contact lens, he felt sick and dizzy and fell unconscious.

CONCLUSION

Our experience suggests that patients with needle phobia may develop vasovagal syncope by concentrating on a fingertip when inserting a contact lens. We need to be aware of unconsciousness because of phobia when trying to insert contact lenses.