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Scheffer C G Tseng

Publications and source records attributed to Scheffer C G Tseng.

At least 19 recordsLinked to original sources
PubMed2007

Niche regulation of corneal epithelial stem cells at the limbus.

Among all adult somatic stem cells, those of the corneal epithelium are unique in their exclusive location in a defined limbal structure termed Palisades of Vogt. As a result, surgical engraftment of limbal epithelial stem cells with or without ex vivo expansion has long been practiced to restore sights in patients inflicted with limbal stem cell deficiency. Nevertheless, compared to other stem cell examples, relatively little is known about the limbal niche, which is believed to play a pivotal role in regulating self-renewal and fate decision of limbal epithelial stem cells. This review summarizes relevant literature and formulates several key questions to guide future research into better understanding of the pathogenesis of limbal stem cell deficiency and further improvement of the tissue engineering of the corneal epithelium by focusing on the limbal niche.

Adult Stem Cells↗
PubMed2006

Intraocular pressure by noncontact tonometry over an amniotic membrane patch in humans.

PURPOSE: To determine the reliability of noncontact tonometry (NCT) in measuring intraocular pressure (IOP) over a combination of amniotic membrane (AM) patch and therapeutic soft contact lens (TSCL) in normal human eyes. DESIGN: Experimental study. METHODS: Twenty-five healthy volunteers (twenty males, five females) participated in this study. After topical anesthesia, IOP was measured using noncontact tonometry before and after the application of a single layer of AM to the right eye and a double layer of AM to the left eye. To enable the IOP measurement by NCT, a TSCL was placed over the AM patch. The thickness of a single or a double layer of AM was measured by pachymetry and correlated with the IOP reading. RESULTS: We found no statistical difference between IOPs measured with and without a combination of a single-layer AM/TSCL (P = .734). In contrast, the IOPs measured over a combination of a double-layer AM/TSCL decreased significantly when compared with the control (P < .0001). The average thicknesses of the single and the double layer of AM were 72.4 +/- 15.0 mum and 126.9 +/- 14.6 mum (mean +/- SD), respectively. There was a negative correlation between total AM thickness and IOP change (r = -.481, P = .0008). CONCLUSIONS: We found that it is reliable to measure IOP by NCT through a combination of a single-layer AM/TSCL on normal human eyes. However, IOP measured by NCT over a combination of a double-layer AM/TSCL was inaccurate and tended to be an underestimation.

Adult↗
PubMed2006

Measurement of light transmittance of cryopreserved human amniotic membrane.

PURPOSE: To measure the light transmission of human amniotic membrane (AM) and compare it with that of therapeutic soft contact lens (TSCL). METHODS: Total light transmittance of each sample (4 AMs and 2 TSCLs) was measured in the 250- to 800-nm range by using a spectrophotometer. RESULTS: The percent light transmission of TSCL was nearly 100% at wavelengths greater than 450 nm, decreased gradually in the sub-450-nm range, and reached 78.4 +/- 3.7 at 250 nm. In contrast, the percent transmission of the 4 AMs decreased gradually and continually throughout the spectrum as wavelength shortened. The transmission of light through AM dropped to less than 20% at 250 nm but remained 90% or more at wavelengths more than 600 nm. CONCLUSION: Light transmittance properties of cryopreserved human AM and human cornea are relatively similar, but AM (and not cornea) allows transmission of 24.6% of UVC.

Amnion↗
PubMed2006

Signaling-transduction pathways required for ex vivo expansion of human limbal explants on intact amniotic membrane.

PURPOSE: Ex vivo expansion of limbal epithelial progenitor cells on amniotic membrane (AM) without 3T3 fibroblasts is a new surgical approach to treat limbal stem cell deficiency. Such expansion requires NGF-TrkA-mediated signaling, and this study was conducted to delineate the downstream signaling pathways. METHODS: The human corneolimbal ring was cut into explants and cultured on intact human AM. At day 0 or 10, low-molecular-weight inhibitors were added, whereas the control group received dimethyl sulfoxide (DMSO). The epithelial outgrowth rate was monitored for 17 days, and the epithelial cells were collected for Western blot analysis. RESULTS: In the control, most expansion of human limbal epithelial cells started from the limbus from days 5 to 7 and reached approximately 80% confluence at day 17. Compared with the control, the outgrowth was completely inhibited by 50 microM LY294002 or 50 microM SR13668 and was significantly suppressed by 10 microM U0126, but was not affected by 10 microM of either SB203580 or JNK inhibitor 1. The inhibition of outgrowth by LY294002, SR13668, and U0126 was reversible. Western blot analysis showed that phosphorylation of Akt and FKHRL1was abolished by LY294002 and SR13668, but downregulated by U0126, which also abolished phosphorylation of p44/42 mitogen-activated protein kinase (MAPK). The phosphorylation of p38 and JNK MAPK were downregulated or abolished during ex vivo expansion. CONCLUSIONS: Ex vivo expansion of human limbal epithelial progenitor cells on intact AM is mediated by the survival signaling pathway mediated by PI3K-Akt-FKHRL1 and by the mitogenic MAPK pathway mediated by p44/42 at the expense of p38 and JNK MAPK.

Amnion↗
PubMed2006

Preservation and expansion of the primate keratocyte phenotype by downregulating TGF-beta signaling in a low-calcium, serum-free medium.

PURPOSE: To demonstrate whether the original keratocyte phenotype is maintained with proliferative activity by suppressing TGF-beta signaling in rhesus monkey keratocytes expanded in a serum-free and low-[Ca2+] medium. METHODS: Rhesus monkey keratocytes were isolated from central corneal buttons by collagenase digestion for 16 hours, seeded on plastic in Dulbecco's modified Eagle's medium (DMEM) containing insulin-transferrin-sodium selenite (ITS) supplement (DMEM/ITS) or 10% fetal bovine serum (DMEM/10% FBS), or in a defined keratinocyte serum-free medium (KSFM). After confluence, cells in KSFM were continuously subcultured at a 1-to-3 split. Cellular proliferation was analyzed by immunostaining for Ki67 and the MTT assay. The cellular phenotype was determined by immunostaining for aldehyde dehydrogenase (ALDH), keratocan, and CD34 and by the expression of keratocan promoter-driven enhanced cyan fluorescent protein (ECFP). The stability of the keratocyte phenotype was examined by switching KSFM to DMEM/ITS and DMEM/10% FBS. TGF-beta signaling was monitored by measuring the promoter activity of TGF-beta1, -beta2, and -beta RII after transient adenoviral transfection, and cytolocalization of Smad2 and Smad4. RESULTS: In KSFM, monkey keratocytes proliferated while maintaining the expression of keratocan, CD34, and ALDH proteins and keratocan promoter-driven ECFP for at least 15 passages. The nuclear accumulation of Smad2 and Smad4 and the promoter activities of TGF-beta1 and -beta RII were significantly downregulated in KSFM compared with DMEM/10% FBS. In KSFM, an increase of [Ca2+] to 1.8 mM and addition of 10% FBS synergistically downregulated the keratocan promoter activity, facilitated Smad2 and Smad4 nuclear translocation, and upregulated TGF-beta1 and -beta RII promoter activities. CONCLUSIONS: The normal monkey keratocyte phenotype can be maintained in a low-calcium, serum-free medium by downregulating Smad-mediated TGF-beta signaling.

Adenoviridae↗
PubMed2006

Basement membrane dissolution and reassembly by limbal corneal epithelial cells expanded on amniotic membrane.

PURPOSE: To investigate basement membrane (BM) formation during ex vivo expansion of limbal corneal epithelial cells on intact amniotic membrane (iAM) and epithelially denuded (d)AM. METHODS: Human limbal explants were cultured on iAM and dAM. Expression of BM components, including laminin-5, type IV collagen, type VII collagen, perlecan, integrin alpha6, and epithelial cell differentiation markers such as p63, cytokeratin 3 (K3), and cytokeratin 12 (K12), were investigated by immunostaining. Levels of matrix metalloproteinase (MMP)-2 and MMP-9 and tissue inhibitor of matrix metalloproteinase (TIMP)-1 in the conditioned media were determined by ELISA and gelatin zymography. RESULTS: All four BM components were preserved in both iAM and dAM before culturing, but dissolved 1 week afterward when MMP-2 was increased. Epithelial outgrowth correlated with increased expression of MMP-2 and -9 for both cultures. Resynthesis of BM began with laminin-5 followed by other components. This process took place at 1 week on iAM but at 2 weeks on dAM after culturing. At 4 weeks, BM was more maturely deposited as a linear band from the explant toward the leading edge on iAM and temporally correlated with a sharp decline of MMP-9 levels. In contrast, such BM deposition began at the leading edge on dAM only when TIMP-1 levels were increased. Epithelial cell outgrowth on iAM expressed more p63 but less K3 and K12 than did that on dAM. CONCLUSIONS: After dissolution of original amniotic BM, new BM formed by ex vivo expanded human limbal corneal epithelial cells on iAM deposits much faster and is more mature, resulting in regeneration of a limbal epithelial phenotype. In contrast, BM deposition is delayed and remains immature on dAM, resembling wound healing by a corneal epithelial phenotype. Thus, BM resynthesis may be used as another objective readout for assessing the success of ex vivo expansion of limbal epithelial progenitor cells on AM.

Amnion↗
PubMed2005

Amniotic membrane transplantation in acute phase of toxic epidermal necrolysis with severe corneal involvement.

OBJECTIVE: To report successful management of acute stage toxic epidermal necrolysis (TEN) by amniotic membrane transplantation. DESIGN: Interventional case report. METHOD/INTERVENTION: A 6-year-old boy who had convulsions and fever due to encephalitis was treated by oral phenobarbital. Two weeks later, he developed a high fever and skin rashes involving >40% of the body, with a positive Nikolsky sign and oral blisters. Examination under general anesthesia performed 5 days after the onset of eye symptoms showed severe inflammation and ulceration on the lid margin and the tarsal conjunctiva in both eyes, a total corneal epithelial defect in the right eye, and a geographical corneal epithelial defect in the left eye. Amniotic membrane was transplanted in both eyes as a patch to cover the entire ocular surface, including upper and lower lid margins. RESULTS: Fourteen days after amniotic membrane transplantation, complete corneal and conjunctival epithelialization was observed in the left eye. However, a second amniotic membrane transplantation was performed in the right eye, which still had a total corneal and conjunctival epithelial defect, and resulted in complete epithelialization 14 days later. Corrected visual acuity improved to 20/16 without any superficial punctate keratitis in both eyes 6 months postoperatively. Minimal symblepharon and peripheral scarring were observed only in the right eye. CONCLUSIONS: Amniotic membrane transplantation performed at the acute phase of TEN is highly effective not only in reducing inflammation and preventing scarring in the conjunctival surface, but also in restoring corneal epithelial integrity in eyes with both corneal and conjunctival ulceration. As a result, in this case it prevented sight-threatening cicatricial complications at the chronic stage.

Acute Disease↗
PubMed2005

Amniotic membrane induces apoptosis of interferon-gamma activated macrophages in vitro.

Amniotic membrane (AM) used as a temporary or permanent graft for ocular surface reconstruction has a potent anti-inflammatory effect. We would like to investigate the mechanism whereby AM induces macrophage apoptosis in vitro. Mouse macrophages, Raw 264.7 cells, were cultured on plastic, type I collagen, corneal stromal slice or AM stromal matrix in serum-free medium with or without interferon-gamma (IFN-gamma). Cells were stained by LIVE/DEAD assay, Hoechst-33342, and TUNEL assay for cell death and apoptosis. Cell lysates and conditioned media were analysed by Cell Death Detection ELISA assay for quantitation of apoptosis. Conditioned media were also analysed by Griess assay for the nitrite concentration and ELISA assay for tumour necrosis factor alpha (TNF-alpha) concentration. Lysates of cells were subjected to Western blot analyses of IKK-alpha, IKK-beta, p65 (RelA) subunit of nuclear factor kappaB (NF-kappaB), total Akt, phospho-Akt (Ser473), and phospho-FKHR (Thr24)/phosphor-FKHRL1 (Thr32). At 48hr after cultivation, cells showed a low level of apoptosis when cultured on plastic, type I collagen and corneal stromal slice with or without IFN-gamma and on AM without IFN-gamma. Nevertheless, cells showed a significant increase of apoptosis when cultured on AM with IFN-gamma activation, and this phenomenon became apparent only after 48 hr. IFN-gamma-activated macrophages on plastic continuously produced nitric oxide (NO) and TNF-alpha during 72 hr culturing. In contrast, there was no NO and TNF-alpha production after 48 hr culture on AM. NO inhibitors, L-NMMA and L-NIL, attenuated NO production of IFN-gamma-activated macrophages on AM, while apoptosis was not decreased accordingly. Expression of IKK-alpha, IKK-beta, p65 (RelA) subunit of NF-kappaB total Akt, phosopho-Akt (Ser473), and phospho-FKHR (Thr24)/FKHRL1 (Thr32) was all down-regulated in IFN-gamma-activated macrophages cultured on AM. In conclusion, AM stromal matrix induces apoptosis of IFN-gamma activated, but not non-activated macrophages, not through the generation of NO, but instead by down-regulating anti-apoptotic NF-kappaB and Akt-FKHR signalling pathways.

Amnion↗
PubMed2005

Mitomycin C, amniotic membrane transplantation and limbal conjunctival autograft for treating multirecurrent pterygia with symblepharon and motility restriction.

BACKGROUND: Treatment of eyes with multirecurrent pterygia associated with severe symblepharon and motility restriction is challenging. A combined surgical procedure of intraoperative mitomycin C, amniotic membrane transplantation and conjunctival limbal autograft was applied for treating such eyes. METHODS: Seven eyes of seven patients who had previously undergone an average of four operations for pterygial removal and who manifested recurrent pterygia associated with severe symblepharon and motility restriction were involved in this retrospective study. The surgical procedures involved clearing fibrovascular membrane over the cornea, extensive excision of epibulbar fibrovascular tissue to the bare sclera, application of 0.02% mytomycin C onto the bare sclera for 5 min and transplantation of preserved human amniotic membrane and conjunctival limbal autograft. RESULTS: Postoperatively, all seven eyes showed rapid epithelialization on the corneal surface in 3-5 days and, on the conjunctival surface, in 10-18 days. For a mean follow-up period of 22.4+/-6.1 months, six eyes recovered deep fornices, smooth and stable ocular surface and full ocular motility without recurrence. One eye showed regrowth of fibrovascular tissue and motility restriction but less severe than before surgery. No complication was noted due to mitomycin C. CONCLUSIONS: Combined intraoperative mitomycin C, amniotic membrane graft and limbal conjunctival autograft are successful approaches for treating multirecurrent pterygia with severe symblepharon to restore the ocular surface integrity and prevent recurrence.

Adult↗
PubMed2005

Keratocan expression of murine keratocytes is maintained on amniotic membrane by down-regulating transforming growth factor-beta signaling.

Keratocytes in the corneal stroma express keratan sulfate-containing proteoglycans including cornea-specific keratocan. On plastic dishes, human, bovine, and rabbit keratocytes lose their characteristic dendritic morphology and keratocan expression when cultured in serum-containing media. Herein, we demonstrated that murine keratocytes also acquired a fibroblastic shape and lost keratocan expression after first passage when cultured on plastic in the presence of serum. In contrast, cells expanded on human amniotic membrane (AM) stromal matrix maintained a three-dimensional dendritic morphology and expressed keratocan mRNA and protein for at least 8 passages before senescence. When keratocytes were cultured on AM, the promoter activity of transforming growth factor (TGF)-beta2 and TGF-beta receptor II was down-regulated as compared with that on plastic. Furthermore, cells on AM continuously retained Smad 2 and Smad 4 in the cytoplasm and did not express alpha-smooth muscle actin, even when 10 ng/ml TGF-beta1 was added in a serum-free medium for up to 5 days. In parallel to such down-regulation of TGF-beta signaling, keratocan promoter-driven ECFP expression was observed in cells cultured either on AM in the presence of serum or on plastic containing serum treated with a neutralizing antibody to TGF-beta. Collectively, these results indicate that down-regulation of Smad-mediated TGF-beta signaling is an important mechanism for cultured keratocytes to maintain a normal phenotype while continuously expanded in a serum-containing medium. This strategy of suppressing TGF-beta signaling, achieved by AM stromal matrix in part via suppression of TGF-beta gene transcription, can be used to expand keratocytes in culture without the use of AM in the future.

Animals↗
PubMed2005

Amniotic membrane maintains the phenotype of rabbit retinal pigment epithelial cells in culture.

The success of surgical removal of choroidal neovascularisation followed by transplantation of autologous retinal pigment epithelial cells (RPE) for age-related macular degeneration (ARMD) may be limited by damage in Bruch's membrane. We investigated whether amniotic membrane (AM) might be used as an alternative basement membrane-containing matrix to support RPE growth and differentiation. Primary RPE plastic cultures were established from freshly enucleated Dutch belted rabbit eyes in DMEM/F12 containing 0.1 mM Ca(++) and 10% dialysed FBS. Upon subconfluence, cells were subcultured at 5000-9000 cells cm(-2) in the above-mentioned culture medium on intact AM (iAM), epithelially denuded AM (dAM) or plastic. After confluence, the Ca(++) concentration in the medium was increased to 1.8 mm for 4 weeks. Growth and morphology were monitored by phase contrast microscopy, and the phenotype by immunostaining with antibodies against cytokeratin 18, tight junction protein ZO-1, and RPE65 protein, and by transepithelial resistance (TER) measurement. Immunostaining to cytokeratin 18 confirmed the epithelial origin of isolated cells in both primary culture and subcultures. Compared to plastic cultures, RPE increased pigmentation within 24 hr after seeding on AM, with iAM being more pronounced than dAM. RPE adopted a hexagonal epithelial phenotype with more organised pigmentation, strong expression of ZO-1 and RPE65, and a significantly higher TER 4 weeks after Ca(++) switch on dAM. Our results indicate that AM may be used as a basement membrane-containing matrix to maintain RPE phenotype in vitro, and may facilitate subsequent transplantation to treat ARMD.

Amnion↗
PubMed2005

Lipid tear deficiency in persistent dry eye after laser in situ keratomileusis and treatment results of new eye-warming device.

PURPOSE: To determine whether lipid tear deficiency is a significant pathogenic factor in persistent dry eyes after laser in situ keratomileusis (LASIK). SETTING: Ocular Surface Center, Miami, Florida, USA. METHODS: Thirty-four eyes of 17 patients (mean 46.35 years +/- 11 [SD]) complaining of persistent dryness more than 12 months after LASIK were prospectively studied by symptom scoring and kinetic analysis of tear interference image, tear breakup time, and fluorescein clearance test. Once patients had been clear of inflammation and treated for aqueous tear deficiency, lipid tear deficiency was further confirmed and treated with Eyefeel (Kao, Inc.), an eye-warming device, 4 times daily for 4 weeks. RESULTS: Sixteen patients were asymptomatic before LASIK but dryness persisted for 41 +/- 19.3 months. Delayed tear clearance was observed in 15 patients (88.2%) and floppy lids in 12 patients (70.5%). Aqueous tear deficiency was reconfirmed in 16 eyes (53.3%). After Eyefeel treatment, there was a subjective improvement of ocular surface diseases index from 60.6 +/- 10.6 to 25.8 +/- 18.5 (P = .0007). Tear breakup time was improved from 2.4 +/- 3.9 seconds to 7.9 +/- 3.6 seconds (P = .004). There was a tear interference pattern change from a vertical lipid tear deficiency to a horizontal normal in 7 eyes. There was a mean lipid spread time improvement from 1.3 +/- 0.4 sec to 0.8 +/- 0.4 sec (P = .001), and there was a mean lipid thickness improvement from 63.5 +/- 23 nm to 79.5 +/- 27 nm (P = .04). CONCLUSION: Persistent nature of dry eye after LASIK is attributed to in part to delayed tear clearance, undercorrected aqueous tear deficiency, and nonrecognized lipid tear deficiency.

Adult↗
PubMed2005

Correlation of corneal complications with eyelid cicatricial pathologies in patients with Stevens-Johnson syndrome and toxic epidermal necrolysis syndrome.

PURPOSE: To look at the correlation between many factors (time of hospitalization, floppy eyelid syndrome, trichiasis, open lacrimal puncta, symblepharon, and aqueous tear deficiency) and corneal complications in Stevens-Johnson syndrome (SJS). DESIGN: Observational cases series. PATIENTS: Clinical data were retrospectively reviewed from 38 patients (32.7+/-20.1 years old) with SJS (n = 11) and with toxic epidermal necrolysis (TENS) (n = 27) from January 2002 to August 2004. One case report with SJS was included to verify the presence of tarsal/lid margin ulceration at the acute stage. METHODS: The medical history was retrieved regarding presumed causative medications used within 15 days and the duration of hospitalization. Data of the latest photographic documentation and eye examination were compared and correlated in a masked fashion. MAIN OUTCOME MEASURES: Floppy eyelid, trichiasis, lid margin keratinization, meibomian gland orifice metaplasia, symblepharon, tarsal scar, and corneal complications. RESULTS: Acute SJS/TENS was characterized by tarsal conjunctival ulceration. Keratinization of the eyelid margin with variable degrees of meibomian gland dysfunction was observed in all cases. Floppy eyelid, trichiasis, partially or totally opened lacrimal punctum, symblepharon, and aqueous tear deficiency were not significantly correlated with corneal complications. In contrast, there was a strong correlation between the severity of eyelid margin and tarsal pathology and the extent of corneal complications (Spearman r, 0.54; P = 0.0005). A multivariable regression analysis also showed that the extent of eyelid and tarsal pathology had a significant effect on corneal complications (coefficient, 0.84; P = 0.006). CONCLUSIONS: Patients with acute SJS/TENS are characterized by severe inflammation and ulceration of the tarsal conjunctiva and lid margins. If left unattended, lid margin keratinization and tarsal scar, together with lipid tear deficiency, contribute to corneal complications because of blink-related microtrauma. Attempts to suppress inflammation and scarring by amniotic membrane transplantation at the acute stage and to prevent microtrauma at the chronic stage are vital to avoid sight-threatening complications.

Adolescent↗
PubMed2005

Intraoperative mitomycin C and amniotic membrane transplantation for fornix reconstruction in severe cicatricial ocular surface diseases.

PURPOSE: To investigate whether intraoperative application of mitomycin C may enhance the success of amniotic membrane transplantation in symblepharon lysis and fornix reconstruction in severe cicatricial ocular surface diseases. DESIGN: Noncomparative interventional case series. PARTICIPANTS: Sixteen patients (8 female, 8 male; 18 eyes) with a mean age of 41+/-23.4 years (range, 3-79) and suffering from severe chemical/thermal burns (7 eyes), multiple recurrent pterygia and pseudopterygia (5 eyes), Stevens-Johnson syndrome (4 eyes), and ocular cicatricial pemphigoid (2 eyes) were consecutively enrolled. All except for 2 eyes had had prior surgical attempts of surgical reconstruction, including 6 eyes with a mucous membrane graft (MMG), but still presented with symblepharon and persistent ocular surface inflammation. INTERVENTION: After excision of subconjunctival fibrovascular tissues, 0.04% mitomycin C was applied for 5 minutes in the deep fornix before amniotic membrane transplantation. MAIN OUTCOME MEASURES: Deeper fornix, noninflamed ocular surface, and full motility. RESULTS: The mean epithelial healing time was 4.2+/-1.9 weeks. During the follow-up of 14.16+/-5.2 months, all eyes showed a marked reduction of conjunctival inflammation, a deep fornix, and a continuous tear meniscus. Of 12 eyes with motility restriction, 2 eyes with multiple recurrent pterygia and 1 eye with severe thermal burn showed recurrence of partial motility restriction 2 months after surgery. The vision of 9 eyes was successfully restored by an additional keratolimbal allograft with subsequent penetrating keratoplasty (6 eyes). CONCLUSION: Intraoperative application of mitomycin C is an effective means to reduce chronic and deep-seated conjunctival inflammation, and helps amniotic membrane restore a deep fornix after symblepharon lysis, even in eyes that had a failed MMG. Restoration of deep fornix and tear meniscus is an important prerequisite to achieve successful reconstruction by subsequent limbal stem cell transplantation.

Adolescent↗
PubMed2005

Intrastromal invasion by limbal epithelial cells is mediated by epithelial-mesenchymal transition activated by air exposure.

Corneal epithelial stem cells are located in the basal layer of the limbus between the cornea and the conjunctiva. Regulation of these limbal epithelial progenitor cells by the stromal niche dictates corneal surface health. To further characterize this process, limbal explants were cultured at the air-fluid interface, termed air-lifting, to stimulate the niche. As compared to submerged cultures, air-lifting significantly promoted epithelial stratification, migration, proliferation, and intrastromal invasion by limbal epithelial cells. Epithelial intrastromal invasion was noted when the limbal, but not corneal, epithelium was recombined with the limbal stroma containing live, but not dead, cells. Invading limbal basal cells displayed up-regulated nuclear expression of p63 and Ki67, down-regulated E-cadherin and cornea-specific keratin 3, and switched expression of beta-catenin from intercellular junctions to the nucleus and cytoplasm, indicating the activation of the Wnt/beta-catenin pathway. Invaded cells isolated by collagenase from the stroma of air-lifted, but not submerged, explants showed vivid clonal growth on 3T3 fibroblast feeder layers and complete epithelial-mesenchymal transition by expressing nuclear p63 and cytoplasmic S100A4. These findings collectively suggest that epithelial-mesenchymal transition via the Wnt/beta-catenin pathway influences the fate of limbal epithelial cells, likely to be progenitor cells, between regeneration and fibrosis when the stromal niche is activated.

Air↗
PubMed2005

Detection of corneal epithelial defect through amniotic membrane patch by fluorescein.

PURPOSE: To demonstrate the usefulness of fluorescein dye to detect a corneal epithelial defect through an amniotic membrane patch in 4 cases. PATIENTS AND METHOD: Two patients with painful bullous keratopathy, 1 patient with total limbal deficiency, and 1 patient with acute chemical burn underwent surgeries in conjunction with amniotic membrane as patch. Postoperatively, slit-lamp biomicroscopic examination with and without fluorescein staining was performed. RESULTS: The status of epithelialization, ie, corneal epithelial defect on either denuded corneal stroma or amniotic membrane graft, was indiscernible by slit-lamp biomicroscopy through the amniotic membrane patch. Nevertheless, it could be detected by fluorescein staining, especially after saline rinse, in all 4 cases. CONCLUSIONS: Fluorescein staining permits clinicians to avoid prematurely removing the amniotic membrane patch during the treatment of a persistent corneal epithelial defect.

Administration, Topical↗
PubMed2005

Tear film dynamics in floppy eyelid syndrome.

PURPOSE: Floppy eyelid syndrome (FES) presents nonspecific ocular surface irritation. The hypothesis for the current study was that one contributing factor is the abnormality in tear film dynamics. METHODS: Sixteen patients with FES were consecutively examined. Tear film dynamics were evaluated by kinetic tear interference images, infrared thermometry, water evaporation rate, tear break-up time, and fluorescein clearance test. Data showing evaporation rate and thermometry were compared with those of 10 normal subjects. RESULTS: There was a high correlation between the eye with the worse symptoms and the eyes with the more severe floppy lids (P < 0.01) and with ocular surface evaporation rate (P = 0.02). Except for one patient, all others showed abnormal tear film, with an average tear break-up time of 2.9 +/- 3.7 seconds. Kinetic analysis of tear interference images revealed that lipid spread in a vertical or mixed pattern in 18 eyes (75%) with a delayed spread time (P = 0.0007), indicating that most of the patients had lipid tear deficiency. The ocular skin temperature and water evaporation rate were higher in the FES group (P = 0.0003 and 0.026, respectively). Nearly all patients with FES showed eyelid hyperpigmentation. The ocular surface evaporation rate in the FES group was also higher than that of the normal subjects (P < 0.0001). Multiple regression analysis showed that a vertical pattern of lipid spread had a significant influence on ocular surface evaporation rate (P = 0.003). CONCLUSIONS: Tear film abnormality is prevalent in patients with FES and is characterized by lipid tear deficiency, leading to rapid tear evaporation. The FES lid skin is also characterized by high temperature, high water evaporation rate, and hyperpigmentation. Studies directed to investigating the linkage of lid changes and meibomian gland dysfunction may shed new lights on the pathogenesis of FES.

Adult↗