Effect of topical administration of epidermal growth factor on healing of corneal epithelial defects in horses

Advanced platelet-rich fibrin promotes healing of induced corneal ulcer in donkeys (Equus asinus)

Ulcerative keratitis is a common disease in horses which may cause blindness. To prevent secondary bacterial and fungal infections and promote quick re-growth of the epithelial layer, different treatment approaches have been employed. This study aimed to examine the effects of advanced platelet-rich fibrin (A-PRF) gel on the healing process of experimentally induced corneal ulcers in donkeys. Nine healthy adult donkeys were used for the study. The donkeys were divided into two groups: the control group, where no medication was applied to the corneal ulcer, and the A-PRF gel group, where A-PRF gel was applied once a day on specific days after ulcer induction. The healing process was evaluated through various examinations and analyses. The results demonstrated that the A-PRF gel group showed significant improvement in the corneal ulcer area, with epithelial and stromal regeneration. At day 35, about 60% of the A-PRF group showed negative fluorescein uptake. Additionally, fewer complications were observed during the healing process compared to the control group. In conclusion, A-PRF gel is an important and safe therapeutic option for controlling ocular surface infection and promoting corneal healing. We recommend using A-PRF gel as an alternative approach, avoiding eyelid suturing, and minimizing corneal irritation.

Equine Umbilical Cord Serum Composition and Its Healing Effects in Equine Corneal Ulceration

Background

Human autologous serum (AS) and umbilical cord serum (UCS) both contain growth and neurotrophic factors that promote corneal healing.

Aim

Our objectives were to compare equine AS and UCS cytokine and growth factor profiles and to assess the safety and clinical feasibility of the therapeutic use of UCS eye drops in cases of spontaneous complex ulcers.

Study Design

Prospective clinical trial.

Methods

Vitamin A insulin growth factor, platelet-derived growth factor-BB, transforming growth factor (TGF)-β1 (enzyme-linked immunosorbent assay), interleukin (IL)-1β, IL-6, interferon-γ, and monocyte chemoattractant protein 1 concentrations were determined in 10 AS collected from different horses and 10 UCS sampled at delivery. Six client-owned horses presenting with complex non-healing corneal defects of >5 mm² were included in a clinical trial and treated with conventional therapy and conditioned UCS drops for 8–15 days. Ulcer surface and time to complete epithelialization were recorded.

Results

Median concentrations of vitamin A, insulin growth factor, and platelet-derived growth factor-BB were not significantly different in AS compared with UCS (respectively, 14.5 vs. 12.05 μg/ml; 107.8 vs. 107.3 pg/ml; and 369.1 vs. 924.2 pg/ml). TGF-β1 median concentration in UCS was significantly higher than in AS (3,245 vs. 2571pg/ml) (p = 0.04). IL-1β, IL-6, interferon-γ, and monocyte chemoattractant protein 1 concentrations were variable in AS and undetectable in UCS. The corneal median ulcerative area was 37.2 mm² (6.28–57.14 mm²) and had a duration of 4–186 days (median 19 days). All lesions healed within 13–42 days (median 17 days). No adverse effects nor recurrences within 1 month were noticed.

Limitations

The sample size was small. Spontaneous corneal epithelial defects presented with variable clinical characteristics. There were no age-matched control horses to assess corneal healing time and rate.

Conclusion and Clinical Significance

Equine UCS may be beneficial, as it contains no pro-inflammatory cytokines and a greater concentration of TGF-β1 compared with AS. Topical UCS appears safe and may potentially be used as adjunctive therapy for equine complex non-healing ulcers.

Interleukin-6 and lactate dehydrogenase expression in a novel ex vivo rocking model of equine corneal epithelial wound healing

PURPOSE

To establish a physiologically relevant ex vivo model of equine corneal epithelial wound healing.

METHODS

Fourteen equine corneas were randomly assigned to one of two groups: wounded (n = 8) or unwounded (n = 6) controls. In the wounded group, the axial corneal epithelium was removed by applying a 6 mm filter paper disk soaked in 1N-NaOH for 60 s. Corneas were subsequently cultured using an air-liquid interface model. Evaluation of corneal healing was performed daily, and culture medium was collected. Corneas were randomly assigned to undergo processing via histopathology and RNAscope in situ hybridization for interleukin-6 (IL-6) and alpha-smooth muscle actin (αSMA) expression at T24, T48, and T72 h after wounding. Media of the cultured corneas were evaluated for the presence of lactate dehydrogenase (LDH) by a colorimetric assay.

RESULTS

The ulcerated area of the wounded corneas decreased over time and all corneas healed within 72 h. Histologically, normal corneal architecture was observed including healthy epithelium (in areas other than the ulcerated ones), minimal stromal edema, intact endothelium, and Descemet's membrane. IL-6 expression was increased in wounded corneas compared with unwounded controls. LDH expression was elevated for both wounded and unwounded corneas at T24 but decreased substantially and was not detected at T48 in media from wounded and unwounded corneas, respectively. No αSMA expression was detected from either wounded or unwounded corneas.

CONCLUSIONS

The equine air-liquid interface, ex vivo, corneal epithelial wound healing model is effective and physiologically relevant. This model can be used in future studies evaluating various corneal therapies.

The Human Tissue-Engineered Cornea (hTEC): Recent Progress

Each day, about 2000 U.S. workers have a job-related eye injury requiring medical treatment. Corneal diseases are the fifth cause of blindness worldwide. Most of these diseases can be cured using one form or another of corneal transplantation, which is the most successful transplantation in humans. In 2012, it was estimated that 12.7 million people were waiting for a corneal transplantation worldwide. Unfortunately, only 1 in 70 patients received a corneal graft that same year. In order to provide alternatives to the shortage of graftable corneas, considerable progress has been achieved in the development of living corneal substitutes produced by tissue engineering and designed to mimic their in vivo counterpart in terms of cell phenotype and tissue architecture. Most of these substitutes use synthetic biomaterials combined with immortalized cells, which makes them dissimilar from the native cornea. However, studies have emerged that describe the production of tridimensional (3D) tissue-engineered corneas using untransformed human corneal epithelial cells grown on a totally natural stroma synthesized by living corneal fibroblasts, that also show appropriate histology and expression of both extracellular matrix (ECM) components and integrins. This review highlights contributions from laboratories working on the production of human tissue-engineered corneas (hTECs) as future substitutes for grafting purposes. It overviews alternative models to the grafting of cadaveric corneas where cell organization is provided by the substrate, and then focuses on their 3D counterparts that are closer to the native human corneal architecture because of their tissue development and cell arrangement properties. These completely biological hTECs are therefore very promising as models that may help understand many aspects of the molecular and cellular mechanistic response of the cornea toward different types of diseases or wounds, as well as assist in the development of novel drugs that might be promising for therapeutic purposes.

Commercial amniotic membrane extract for treatment of corneal ulcers in adult horses

BACKGROUND

Amniotic membrane extract enhances the rate of epithelialisation after corneal ulceration in several species but has not been studied in the equine cornea.

OBJECTIVES

To evaluate the effect of amniotic membrane extract on re-epithelialisation of equine corneal ulcers compared with ulcers treated with antibiotic, antifungal and mydriatic medical therapy alone, and to evaluate equine corneal healing after experimentally induced superficial ulceration.

STUDY DESIGN

Masked, randomised, controlled experimental trial.

METHODS

Superficial, 8 mm corneal ulcers were created bilaterally in each horse. One eye was treated with amniotic membrane extract and the opposite was control. Both eyes were treated with medical therapy. Treatment eyes received amniotic membrane extract, and control eyes received the amniotic membrane extract vehicle. Ulcers were stained with fluorescein and photographed in 12-hour increments until completely healed. Ulcer surface area was determined by analysing photographs with ImageJ. A mixed linear model was used to compare ulcer surface area and hours until healing between treatment groups. A regression model was also used to calculate corneal re-epithelialisation rate over time.

RESULTS

Regardless of therapy, healing occurred in two phases: an initial rapid phase of 0.88 mm² /hr (95% CI: 0.81-0.94 mm² /hr) for approximately 48-54 hours followed by a second, slow phase of 0.07 mm² /hr (95% CI: 0.04-0.09 mm² /hr). Most eyes healed within 135.5 ± 48.5 hours. Treatment (amniotic membrane extract vs. control) was not significantly associated with size of ulcers over time (P = .984). Discomfort was minimal to absent in all horses.

MAIN LIMITATIONS

Results achieved experimental studies may differ from outcomes in the clinical setting.

CONCLUSIONS

There was no significant difference in healing rate with addition of amniotic membrane extract to medical therapy for equine superficial corneal ulcers. A biphasic corneal healing process was observed, with an initial rapid phase followed by a slow phase. Further study will be needed to determine whether amniotic membrane extract will be helpful for infected or malacic equine corneal ulcers.

Effect of bone marrow-derived mesenchymal stem cells and stem cell supernatant on equine corneal wound healing in vitro

Background

We aimed to determine and compare the in vitro effects of autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) and mesenchymal stem cell supernatant (MSC-Sp) on the wound healing capacity of equine corneal fibroblasts using a scratch assay.

Methods

Bone marrow aspirates and eyes were collected from normal, euthanized horses with subsequent isolation and culture of BM-MSCs and corneal stromal cells. Corneal stromal cells were culture-expanded in the culture well of transwell plates and then treated with an autologous BM-MSC suspension (dose: 2.5 × 10⁵/100 μL media with the BM-MSCs contained within the insert well), MSC-Sp solution, or naive culture media (control) for 72 h. A linear defect in confluent cell cultures was created (i.e., corneal scratch assay) to assess the cellular closure (“healing”) over time. Three representative areas of the scratch in each culture were photographed at each time point and the scratch area was quantitated using image analysis software (ImageJ). Media from the scratches were analyzed for various growth factors using human enzyme-linked immunosorbent assay (ELISA) kits that crossreact with the horse.

Results

There was a significant percentage decrease in the scratch area remaining in the BM-MSC and MSC-Sp groups compared to the control group. There was also a significant percentage decrease in the scratch area remaining in the BM-MSC group compared to the MSC-Sp group at 36 h post-scratch and all time points thereafter. The concentration of transforming growth factor (TGF)-β1 in the media was significantly higher in the BM-MSC group compared to the control group.

Conclusions

The significant decrease in scratch area in equine corneal fibroblast cultures treated with autologous BM-MSCs compared to MSC-Sp or control treatments suggests that BM-MSCs may substantially improve corneal wound healing in horses. MSC-Sp may also improve corneal wound healing given the significant decrease in scratch area compared to control treatments, and would be an immediately available and cost-effective treatment option.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0577-3) contains supplementary material, which is available to authorized users.

Administration of Menadione, Vitamin K3, Ameliorates Off-Target Effects on Corneal Epithelial Wound Healing Due to Receptor Tyrosine Kinase Inhibition

PURPOSE

The antiangiogenic receptor tyrosine kinase inhibitor (RTKi), 3-[(4-bromo-2,6-difluorophenyl)methoxy]-5-[[[[4-(1-pyrrolidinyl) butyl] amino] carbonyl]amino]-4-isothiazolecarboxamide hydrochloride, targets VEGFR2 (half maximal inhibitory concentration [IC50] = 11 nM); however, off-target inhibition of epidermal growth factor receptor (EGFR) occurs at higher concentrations. (IC50 = 5.8 μM). This study was designed to determine the effect of topical RTKi treatment on EGF-mediated corneal epithelial wound healing and to develop new strategies to minimize off-target EGFR inhibition.

METHODS

In vitro corneal epithelial wound healing was measured in response to EGF using a transformed human cell line (hTCEpi cells). In vivo corneal wound healing was assessed using a murine model. In these complementary assays, wound healing was measured in the presence of varying RTKi concentrations. Immunoblot analysis was used to examine EGFR and VEGFR2 phosphorylation and the kinetics of EGFR degradation. An Alamar Blue assay measured VEGFR2-mediated cell biology.

RESULTS

Receptor tyrosine kinase inhibitor exposure caused dose-dependent inhibition of EGFR-mediated corneal epithelial wound healing in vitro and in vivo. Nanomolar concentrations of menadione, a vitamin K3 analog, when coadministered with the RTKi, slowed EGFR degradation and ameliorated the inhibitory effects on epithelial wound healing both in vitro and in vivo. Menadione did not alter the RTKi's IC50 against VEGFR2 phosphorylation or its inhibition of VEGF-induced retinal endothelial cell proliferation.

CONCLUSIONS

An antiangiogenic RTKi exhibited off-target effects on the corneal epithelium that can be minimized by menadione without deleteriously affecting its on-target VEGFR2 blockade. These data indicate that menadione has potential as a topical supplement for individuals suffering from perturbations in corneal epithelial homeostasis, especially as an untoward side effect of kinase inhibitors.

The tissue-engineered human cornea as a model to study expression of matrix metalloproteinases during corneal wound healing

Corneal injuries remain a major cause of consultation in the ophthalmology clinics worldwide. Repair of corneal wounds is a complex mechanism that involves cell death, migration, proliferation, differentiation, and extracellular matrix (ECM) remodeling. In the present study, we used a tissue-engineered, two-layers (epithelium and stroma) human cornea as a biomaterial to study both the cellular and molecular mechanisms of wound healing. Gene profiling on microarrays revealed important alterations in the pattern of genes expressed by tissue-engineered corneas in response to wound healing. Expression of many MMPs-encoding genes was shown by microarray and qPCR analyses to increase in the migrating epithelium of wounded corneas. Many of these enzymes were converted into their enzymatically active form as wound closure proceeded. In addition, expression of MMPs by human corneal epithelial cells (HCECs) was affected both by the stromal fibroblasts and the collagen-enriched ECM they produce. Most of all, results from mass spectrometry analyses provided evidence that a fully stratified epithelium is required for proper synthesis and organization of the ECM on which the epithelial cells adhere. In conclusion, and because of the many characteristics it shares with the native cornea, this human two layers corneal substitute may prove particularly useful to decipher the mechanistic details of corneal wound healing.

Galectin-3 enhances extracellular matrix associations and wound healing in monkey corneal epithelium

Poor healing of epithelial wounds in cornea is a major clinical problem, leading to persistent epithelial defects and ulceration. The primary cause is poor cell migration over the wound. Carbohydrate-binding protein galectin-3 binds to extracellular matrixes (ECMs) and promotes lamellipodia formation by cross-linking to α3 integrin. Recombinant galectin-3 also facilitates wound healing in the rodent cornea. The purposes of the present experiments were to: (1) establish epithelial wound healing models in monkey corneal explant culture, the models more relevant to human, (2) evaluate the healing effect of galectin-3 in our models, and (3) determine if galectin-3 enhances cell adhesion by interacting with ECMs on corneal surface and their ligand integrins. Monkey corneas with central wounds produced by sodium hydroxide (NaOH) or n-heptanol were incubated with or without recombinant galectin-3. The defected area was stained with sodium fluorescein. Primary isolated corneal epithelial cells from monkey were cultured with or without galectin-3 on plates coated with ECMs or integrins, and the number of adhering cells was counted. Galectin-3 expression in various eye tissues was visualized by immunoblotting. NaOH caused loss of epithelial cells and basement membrane. n-Heptanol removed epithelial cells, but the basement membrane was retained. These corneal defects spontaneously became smaller in a time-dependent manner. Exogenous galectin-3 enhanced wound healing in both NaOH and n-heptanol models. Galectin-3 also enhanced cell adhesion onto the major ECMs found in the basement and Bowman's membranes and onto integrins. Relatively high levels of galectin-3 were detected in corneal and conjunctival epithelium, but tear fluid contained negligible galactin-3. These results suggested that the enhanced binding of epithelial cells to ECMs and integrins caused by galectin-3 might promote cell migration over wounded corneal surfaces. Since tear fluid contained relatively low levels of galectin-3, exogenous galectin-3 may be a beneficial drug to enhance re-epithelialization in human corneal diseases.

The role of endogenous epidermal growth factor receptor ligands in mediating corneal epithelial homeostasis

PURPOSE

To provide a comprehensive study of the biological role and therapeutic potential of six endogenous epidermal growth factor receptor (EGFR) ligands in corneal epithelial homeostasis.

METHODS

Kinetic analysis and dose response curves were performed by using in vitro and in vivo wound-healing assays. Biochemical assays were used to determine receptor expression and activity. Human tears were collected and quantitatively analyzed by multianalyte profiling for endogenous EGFR ligands.

RESULTS

Epidermal growth factor receptor ligands improved wound closure and activated EGFR, but betacellulin (BTC) was the most efficacious promoter of wound healing in vitro. In contrast, only epidermal growth factor (EGF) promoted wound healing in vivo. Human tears from 25 healthy individuals showed EGFR ligands at these average concentrations: EGF at 2053 ± 312.4 pg/mL, BTC at 207 ± 39.4 pg/mL, heparin-binding EGF at 44 ± 5.8 pg/mL, amphiregulin at 509 ± 28.8 pg/mL, transforming growth factor-α at 84 ± 19 pg/mL, and epiregulin at 52 ± 15 pg/mL.

CONCLUSIONS

Under unwounded conditions, only EGF was present at concentrations near the ligand's Kd for the receptor, indicating it is the primary mediator of corneal epithelial homeostasis. Other ligands were present but at concentrations 11- to 7500-fold less their Kd, preventing significant ligand binding. Further, the high levels of EGF and its predicted binding preclude receptor occupancy by exogenous ligand and can explain the discrepancy between the in vitro and in vivo data. Therefore, therapeutic use of EGFR ligands may be unpredictable and impractical.

A tissue-engineered corneal wound healing model for the characterization of reepithelialization

Progress in tissue engineering has led to the discovery of technologies allowing reconstruction of autologous tissues from the patient's own cells and the development of new in vitro models to study cellular and molecular mechanisms implicated in wound healing. The outer surface of the eye, the cornea, is involved in the sense of sight, thus an adequate reepithelialization process after wounding is essential in order to maintain corneal function. In this chapter, protocols to generate a new in vitro three-dimensional human corneal wound healing model suitable for studying the different components that play important roles in corneal reepithelialization are described in details. The methods include extraction and culture of human corneal epithelial cells (HCECs), human corneal fibroblasts, a complete description of the cornea reconstructed by tissue-engineering as well as the corneal wound healing model.

Posology, efficacy, and safety of epidermal growth factor eye drops in 305 patients: logistic regression and group-wise odds of published data

The aim of this article is to investigate clinical research on indications, posology, efficacy, and safety of epidermal growth factor (EGF) eye drops in the treatment of some human corneal disorders. Methods used include systematic search and selection of series of cases and clinical trials in Medline database up to January 2012, kappa index (K) to validate retrieval information, cumulative Mantel-Haenszel-stratified meta-analysis, 2×2 contingency table of randomized EGF-vehicle-controlled treated groups, and statistical program SPSSv12. Our results indicate that EGF eye drops appear to be a very effective treatment of acute heterogeneous corneal diseases, without significant adverse effects, with a 86.8% clinical efficacy reported by authors, a 98% (P<0.05) probabilistic expected efficacy, and 51.3 (17.4-148.7 confidence interval 95%; P<0.05) odds ratio EGF/vehicle. However, clinical trials are scarce, with low sample sizes and serious inconsistencies in EGF posology. EGF eye drops (50-1,000 ng, 2-3 times/day) could be a useful treatment for promoting postoperative refractive surgery, reversing cases of keratopathy secondary to systematic EGF receptor inhibitors, diabetic keratopathy, and other corneal and conjunctival disorders.

Infections of the Head and Ocular Structures in the Horse

Infectious conditions of the equine head are commonly encountered in clinical practice. Pathogenic bacterial, viral, and fungal organisms may localize in the extensive nasal passages, paranasal sinuses, and guttural pouches, creating a range of clinical signs and conditions that can be severe enough to lead to unexpected fatality. Renewed interest in equine dentistry has led to a greater recognition of dental disease that is associated with infection. This article focuses on bacterial and fungal infections of the main anatomic regions of the equine head, where advances in diagnosis and management have been made or consolidated in recent years. It also addresses recent advances made in the area of infectious equine corneal disease, including bacterial, viral, and fungal etiologies. Recent developments in equine recurrent uveitis as it relates to infectious diseases and ocular manifestations of systemic disease are also discussed.

Inflammatory stromal keratopathies: medical management of stromal keratomalacia, stromal abscesses, eosinophilic keratitis, and band keratopathy in the horse

This article discusses the diagnosis and medical treatment of stromal keratomalacia or "melting ulcers," stromal abscesses, eosinophilic keratitis (EK), and calcific band keratopathy. These are common and important inflammatory keratopathies of the equine corneal stroma. Keratomalacia and stromal abscesses are associated with infection, leukocytic invasion of the stroma, and loss of tissue and tear film proteinase homeostasis. Eosinophils infiltrate the stroma in response to unknown stimuli in EK. Calcium is deposited in the stroma and epithelium secondary to chronic equine recurrent uveitis in calcific band keratopathy. They are all associated with varying degrees of iridocyclitis.

Superficial, nonhealing corneal ulcers in horses: 23 cases (1989-2003)

OBJECTIVE

To characterize superficial, nonhealing corneal ulcers in the horse and to assess the affect of age, breed, sex, inciting cause of the ulcer, and treatment on healing time of these ulcers.

DESIGN

Retrospective study.

ANIMALS

Twenty-three horses with superficial, nonhealing corneal ulcerations.

PROCEDURE

Medical records from 1989 to 2003 of horses diagnosed with superficial, nonhealing corneal ulcers were reviewed. Signalment, duration of clinical signs, ophthalmic abnormalities, treatment and response to treatment were recorded. Horses were treated, in addition to medical therapy, using debridement, debridement and grid keratotomy, superficial keratectomy, and superficial keratectomy with conjunctival graft placement.

RESULTS

Mean age +/- SD of horses was 13.7 +/- 5.8 years. The mean time of presence of the corneal ulceration was 38.9 +/- 21.3 days. Mean time to complete re-epithelialization of the corneal ulcers after treatment was 20 +/- 14.7 days. Horses treated with debridement alone, grid keratotomy and superficial keratectomy healed in a mean time of 15.3 +/- 14.6 days, 16 +/- 12.6 days, and 22.8 +/- 6.7 days, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Horses treated with a single debridement at initial evaluation healed in a significantly shorter time period than horses treated with grid keratotomy or superficial keratectomy. The latter two procedures may be beneficial in the treatment of nonhealing ulceration in horses, but the results of this study suggest that these procedures should only be performed following failure of the ulcer to heal after epithelial debridement.

Diagnosis and management of chronic corneal epithelial defects (indolent corneal ulcerations)

Chronic corneal epithelial defects (CCEDs; indolent corneal ulcerations) are the most common refractory ulcerations in veterinary medicine and are diagnosed by their classic appearance. CCEDs are superficial ulcerations without stromal involvement and have a nonadherent epithelial border (lip). Fluorescein stain adheres to the exposed stroma and extends below the epithelial border, outlining the epithelial lip. CCEDs occur secondary to adnexal disease, keratoconjunctivitis sicca, exposure keratitis, neurotrophic keratitis, and primary corneal disease. In cats, herpes keratitis is associated with the development of CCEDs. Bacterial infections are not responsible for the refractory nature of CCEDs. Because of the refractory nature of CCEDs, treatment can be frustrating for both owner and veterinarian. Current treatment recommendations consist of identifying and treating the underlying cause and performing procedures that stimulate epithelialization and adhesion of the corneal epithelium. Initial treatment of CCEDs includes ulcer debridement and grid keratotomy. Superficial keratectomy is indicated in refractory cases.

Effects of growth factors (EGF, PDGF-BB and TGF-beta 1) on cultured equine epithelial cells and keratocytes: implications for wound healing

OBJECTIVE

The physiologic mechanisms involving growth factors, including PDGF-BB, EGF, and TGF-beta 1, as potent mediators of fibroblasts and epithelial cells in corneal wound healing remain unknown. The goal of this study was to determine culture methods for equine epithelial cells and keratocytes and to investigate how exogenous growth factors influence proliferation of both cell types.

PROCEDURES

Cell cultures were established from healthy corneas harvested from horses immediately following euthanasia and maintained using standard tissue culture protocols. To determine the effects of PDGF-BB, EGF, TGF-beta 1, keratocytes (1 x 10(5)/well) and epithelial cells (2 x 10(5)/well) were each cultured in 12 well plates and exposed separately to the growth factors. The cells were exposed to concentrations of EGF between 0 and 50 ng/mL; PDGF-BB between 0 and 75 ng/mL; and TGF-beta 1 between 0 and 10 ng/mL. Cell proliferation was measured using 3H-thymidine assay and differences in growth determined using anova and Tukey's HSD test (P < 0.05).

RESULTS

Epithelial cell and keratocyte cultures were successfully established. EGF maximally stimulated keratocyte and epithelial cells at 25 ng/mL and 5 ng/mL, respectively. PDGF-BB maximally stimulated keratocytes and epithelial cells at 50 ng/mL and 5 ng/mL, respectively. TGF-beta 1 inhibited keratocytes at 5 ng/mL and 10 ng/mL, and epithelial cells at 1 ng/mL and 2 ng/mL.

CONCLUSIONS

Methods were established to maintain epithelial cells and keratocytes in vitro. PDGF-BB and EGF stimulate, while TGF-beta 1 inhibits the proliferation of epithelial cells and keratocytes. These growth factors may play a role in maintenance and repair of the equine cornea.