Corneal wound healing promoted by 3 blood derivatives: an in vitro and in vivo comparative study

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.

Ocular-Surface Regeneration Therapies for Eye Disorders: The State of the Art

The ocular surface is a complex structure that includes cornea, conjunctiva, limbus, and tear film, and is critical for maintaining visual function. When the ocular-surface integrity is altered by a disease, conventional therapies usually rely on topical drops or tissue replacement with more invasive procedures, such as corneal transplants. However, in the last years, regeneration therapies have emerged as a promising approach to repair the damaged ocular surface by stimulating cell proliferation and restoring the eye homeostasis and function. This article reviews the different strategies employed in ocular-surface regeneration, including cell-based therapies, growth-factor-based therapies, and tissue-engineering approaches. Dry eye and neurotrophic keratopathy diseases can be treated with nerve-growth factors to stimulate the limbal stem-cell proliferation and the corneal nerve regeneration, whereas conjunctival autograft or amniotic membrane are used in subjects with corneal limbus dysfunction, such as limbal stem-cell deficiency or pterygium. Further, new therapies are available for patients with corneal endothelium diseases to promote the expansion and migration of cells without the need of corneal keratoplasty. Finally, gene therapy is a promising new frontier of regeneration medicine that can modify the gene expression and, potentially, restore the corneal transparency by reducing fibrosis and neovascularization, as well as by stimulating stem-cell proliferation and tissue regeneration.

The Comparison between the Composition of 100% Autologous Serum and 100% Platelet-Rich Plasma Eye Drops and Their Impact on the Treatment Effectiveness of Dry Eye Disease in Primary Sjogren Syndrome

PURPOSE

The aim of the study was to compare the difference in composition between 100% autologous serum (AS) and 100% platelet-rich plasma (PRP) eye drops and assess their impact on the clinical outcomes after the treatment of severe dry eye (DE) in primary Sjogren Syndrome patients (pSS).

MATERIALS AND METHODS

This is an interventional, non-randomized, comparative, three-month study. 22 patients with severe DE in pSS were treated with 100% AS (22 eyes) and 100% PRP (22 eyes) eye drops 5 times per day in monotherapy mode. The quantifications of growth factors (GFs) such as fibroblast growth factor (FGF), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), nerve growth factor (NGF), transforming growth factor (TGF-b), insulin-like growth factor (IGF), fibronectin, and substance p in hemoderivates were done. The main outcome measures were: Ocular Surface Disease Index (OSDI), Best Corrected Visual Acuity (BCVA), the Schirmer test, tear break-up time (TBUT), corneal and conjunctival staining according to the Oxford scale, conjunctival hyperaemia, and Meibomian gland parameters. The results were compared at baseline, 1 month, and 3 months following the treatment. The clinical results were correlated with the concentration of GFs in the biological tear substitutes.

RESULTS

Significant differences were observed in the concentration of FGF (4.42 ± 0.86 vs. 15.96 ± 7.63, p < 0.0001), EGF (4.98 ± 0.97 vs. 39.06 ± 20.18, p < 0.0001), fibronectin (929.6 ± 111.5 vs. 823.64 ± 98.49, p = 0.0005), VEGF (175.45 ± 65.93 vs. 717.35 ± 488.15, p < 0.0001), PDGF AB (619.6 ± 117.30 vs. 349.66 ± 79.82, p < 0.0001), NGF (85.22 ± 23.49 vs. 8.29 ± 9.06, p < 0.0001), PDGF (935.38 ± 434.26 vs. 126.66 ± 54.41, p < 0.0001), substance p (112.58 ± 27.28 vs. 127.51 ± 26.56, p = 0.0125) in PRP compared to AS. The level of TGF-β was undoubtedly higher in AS than in PRP (1031.37 ± 330.23 vs. 726.03 ± 298.95, p = 0.0004). No significant differences between AS and PRP were observed in the concentration of IGF. Therapy with blood products relieved the signs and symptoms in pSS DE patients. There was a statistically significant improvement in BCVA, the Schirmer test, TBUT, Meibomian gland parameters, and the reduction of the OSDI scores, Oxford staining, and conjunctiva hyperaemia in each of the groups. However, the clinical changes were more significant in the PRP group. There were numerous correlations between the level of GFs and the mean change in clinical outcomes. No adverse events were reported.

CONCLUSIONS

Despite the fact that blood derivatives differ in composition, they seem to be effective and safe in the treatment of severe DE in pSS patients. The signs and symptoms of DE were reduced in both groups, but only the mean change in OSDI was statistically significant. A greater reduction in OSDI scores was observed in the PRP group. The obtained results and the composition of haemoderivates may indicate the superiority of PRP in relieving the symptoms of DE in pSS patients compared to AS.

Beneficial Effects of Plasma Rich in Growth Factors (PRGF) Versus Autologous Serum and Topical Insulin in Ocular Surface Cells

PURPOSE

In the last few decades, several blood derived products such as platelet-rich plasma (PRP), plasma rich in growth factors (PRGF) and autologous serum (AS) have been used for the treatment of ocular surface disorders. Recently, insulin has been proposed to be used as an alternative for the treatment of ocular surface diseases. The aim of this study was to evaluate the biological potential of PRGF eye drops in comparison with AS and insulin on ocular surface cells.

METHODS

Blood from three healthy young donors was collected to obtain autologous serum (AS) eye drops and plasma rich in growth factors (PRGF) eye drops. Insulin (Actrapid^®) was diluted at 1 and 0.2 IU/mL. The biological potential of PRGF, AS and insulin was assessed by proliferation in HCE, HK and HConF cells. Wound healing assay was performed in HCE cells after incubation with the different treatments. HConF and HK cells were differentiated to myofibroblast after treatment with 2.5 ng/mL of TGF-β1 and then incubated with all treatments.

RESULTS

PRGF eye drops induced significantly higher proliferation rate compared to AS or insulin in HConF and HK cells, but not in HCE cells. In addition, the percentage of wound healing area was significantly reduced after PRGF treatment in comparison with AS or insulin treatment. Furthermore, PRGF significantly reduced the number of myodifferentiated cells compared to AS and insulin at both concentrations analyzed.

CONCLUSION

The results obtained in the present study show that PRGF increases the biological activity of the ocular surface cells and reduces the expression of fibrosis marker compared to insulin or AS.

TRANSLATIONAL RELEVANCE

The present study suggests that plasma rich in growth factors eye drops are a more effective therapy than insulin and autologous serum eye drops for the treatment of ocular surface diseases.

A multicenter report of the use of plasma rich in growth factors (PRGF) for the treatment of patients with ocular surface diseases in North America

PURPOSE

To investigate the efficacy and safety of plasma rich in growth factors (PRGF) eyedrops in the management of patients with ocular surface diseases in North America.

METHODS

Multicenter interventional case series of patients using PRGF eyedrops for the first time. A cohort of patients was analyzed for corneal staining score at initial visit and at 3 months of therapy with PRGF. Another cohort responded to a 10-item questionnaire that evaluated patients' satisfaction and safety, which included the symptom assessment questionnaire in dry eye (SANDE) score, after 6 months of PRGF treatment.

RESULTS

A total of 153 patients were analyzed. Of these, 102 were reviewed for corneal epitheliopathy and 99 patients responded to the questionnaire. The mean (±SD) age of the population was 63.7 ± 17 years and 72.5% were female. The clinical indications for PRGF usage were dry eye (60%), neurotrophic keratopathy (15%), dormant corneal ulcers (12%), limbal stem cell deficiency (10%), and cicatrizing conjunctivitis (4%). At the final visit, 74.3% of patients showed an improvement of their corneal staining. Those who had punctate epithelial erosions or epithelial defects were reduced from 76.5% to 47% and 23.5%-7.8% respectively (p < 0.0001). Symptoms, measured via SANDE score, significantly decreased from a median of 90 to 34.6 out of 100 points on follow-up (p < 0.0001). Only one patient (0.98%) complained of ocular burning sensation as a side effect.

CONCLUSIONS

This multicentric study demonstrates the safety and efficacy of the use of PRGF for treating signs and symptoms in patients with significant ocular surface diseases.

Autologous versus allogeneic versus umbilical cord sera for the treatment of severe dry eye disease: a double-blind randomized clinical trial

PURPOSE

To measure the effects of Autologous serum (AS), Allogeneic Serum (HS) and Umbilical Cord serum (CS) eye drops in severe dry eye disease (DES), as well as to characterize and quantify several molecules in the three sera (albumin, fibronectin; Vitamin A and E; IgG, IgA and IgM; Transforming growth factor β; Epithelial growth factor).

METHODS

Randomized, double-blind, single-centre, three-arm (AS, HS and CS) clinical trial. Sixty-three subjects were included with severe DES, 21 in each arm of the study. Visual acuity, Schirmer test, Breakup time (BUT), lissamine green, fluorescein staining measurements and a questionnaire were performed prior to treatment, and after one-month and three-month follow-up.

RESULTS

There was a significant main effect of time on visual acuities, Schirmer and BUT tests and fluorescein and lissamine green staining measurements and questionnaire scores (p = 0.015, p = 0.002, p < 0.001, p < 0.001, p = 0.031 and p < 0.001, respectively), although there was no significant interaction between time and serum type, nor between serum type and the test performed. Regarding the concentration of molecules, in our study AS contained significantly higher concentrations of IgA, IgG and fibronectin whereas HS contained significantly higher concentration of IgM, vitamins A and E, TGF and albumin. Contrary to previous reports, CS did not show higher concentration of any of the molecules analysed.

CONCLUSIONS AND RELEVANCE

The three sera were effective in the treatment of severe DES. CS did not contain a higher proportion of molecules compared to AS/HS. More research is needed to assess the effect of AS in patients with DES and autoimmune diseases.

Proteomic Characterization of Plasma Rich in Growth Factors and Undiluted Autologous Serum

Over the last three decades, there has been special interest in developing drugs that mimic the characteristics of natural tears for use it in the treatment of several ocular surface disorders. Interestingly, the composition of blood plasma is very similar to tears. Therefore, different blood-derived products like autologous serum (AS) and plasma rich in growth factors (PRGF) have been developed for the treatment of diverse ocular pathologies. However, scarce studies have been carried out to analyze the differences between both types of blood-derived products. In the present study, blood from three healthy donors was drawn and processed to obtain AS and PRGF eye drops. Then, human corneal stromal keratocytes (HK) were treated with PRGF or undiluted AS. Proteomic analysis was carried out to analyze and characterize the differential protein profiles between PRGF and AS, and the differentially expressed proteins in HK cells after PRGF and AS treatment. The results obtained in the present study show that undiluted AS induces the activation of different pathways related to an inflammatory, angiogenic, oxidative stress and scarring response in HK cells regarding PRGF. These results suggest that PRGF could be a better alternative than AS for the treatment of ocular surface disorders.

Aniridia and the ocular surface: Medical and surgical problems and solutions

Congenital aniridia is a multisystemic genetic disease due to a mutation in PAX6 gene which severely affects the development and functionality of the human eyes. In patients affected by the mutation, aside from the absence or defects of iris tissue formation, abnormalities in position or opacities of the crystalline lens, macular hypoplasia, ocular surface disease is the main cause of visual loss and the deterioration of the quality of life of most patients. Limbal stem cell deficiency combined with tear film instability and secondary dry eye cause aniridic keratopathy which, in advanced stages, ends up in corneal opacification. In this paper, the actual knowledge about congenital aniridia keratopathy physiopathology and medical and surgical treatment options and their efficacy are discussed. Indications and results of topical treatments with artificial tears and blood-derivatives in its initial stages, and different surgical techniques as limbal stem cell transplantation, keratoplasty and keratoprostheses are reviewed. Finally, recent advances and results in regenerative medicine techniques with ex vivo stem cell cultivation or other types of cultivated cells are presented.

The Limbal Niche and Regenerative Strategies

The protective function and transparency provided by the corneal epithelium are dependent on and maintained by the regenerative capacity of limbal epithelial stem cells (LESCs). These LESCs are supported by the limbal niche, a specialized microenvironment consisting of cellular and non-cellular components. Disruption of the limbal niche, primarily from injuries or inflammatory processes, can negatively impact the regenerative ability of LESCs. Limbal stem cell deficiency (LSCD) directly hampers the regenerative ability of the corneal epithelium and allows the conjunctival epithelium to invade the cornea, which results in severe visual impairment. Treatment involves restoring the LESC population and functionality; however, few clinically practiced therapies currently exist. This review outlines the current understanding of the limbal niche, its pathology and the emerging approaches targeted at restoring the limbal niche. Most emerging approaches are in developmental phases but show promise for treating LSCD and accelerating corneal regeneration. Specifically, we examine cell-based therapies, bio-active extracellular matrices and soluble factor therapies in considerable depth.

Kynurenic Acid Accelerates Healing of Corneal Epithelium In Vitro and In Vivo

Kynurenic acid (KYNA) is an endogenous compound with a multidirectional effect. It possesses antiapoptotic, anti-inflammatory, and antioxidative properties that may be beneficial in the treatment of corneal injuries. Moreover, KYNA has been used successfully to improve the healing outcome of skin wounds. The aim of the present study is to evaluate the effects of KYNA on corneal and conjunctival cells in vitro and the re-epithelization of corneal erosion in rabbits in vivo. Normal human corneal epithelial cell (10.014 pRSV-T) and conjunctival epithelial cell (HC0597) lines were used. Cellular metabolism, cell viability, transwell migration, and the secretion of IL-1β, IL-6, and IL-10 were determined. In rabbits, after corneal de-epithelization, eye drops containing 0.002% and 1% KYNA were applied five times a day until full recovery. KYNA decreased metabolism but did not affect the proliferation of the corneal epithelium. It decreased both the metabolism and proliferation of conjunctival epithelium. KYNA enhanced the migration of corneal but not conjunctival epithelial cells. KYNA reduced the secretion of IL-1β and IL-6 from the corneal epithelium, leaving IL-10 secretion unaffected. The release of all studied cytokines from the conjunctival epithelium exposed to KYNA was unchanged. KYNA at higher concentration accelerated the healing of the corneal epithelium. These favorable properties of KYNA suggest that KYNA containing topical pharmaceutical products can be used in the treatment of ocular surface diseases.

Progress in the use of plasma rich in growth factors in ophthalmology: from ocular surface to ocular fundus

Introduction: The use of blood derivatives and especially Plasma rich in growth factors (PRGF), for regenerative purposes has been a common trend along the last decades in the field of oral surgery, dermatology, orthopedics, and more recently in ophthalmology.Areas covered: PRGF is a type of platelet-rich plasma that is being explored for the treatment of ocular injuries. The present review article highlights 50 ophthalmology-related publications about the application of PRGF in the treatment of acute and chronic pathologies in ophthalmology as well as most relevant challenges and future prospects.Expert opinion: PRGF technology provides a wide range of formulations that can be used therapeutically in many different acute and chronic ocular pathologies. In addition to eye drops enriched with autologous growth factors, PRGF enables the preparation of both immunologically safe and fibrin-based formulations. Recent advances in the field have promoted PRGF storage for 12 months under freezing conditions, its daily use for 7 days at room temperature and the freeze-dried formulation. The thermally treated immunosafe formulation has shown promising clinical results for the treatment of several diseases such as Sjögren syndrome, graft versus host disease or cicatrizing conjunctivitis. In addition, several fibrin formulations have been preclinically evaluated and clinically incorporated as an adjuvant to ocular surface or glaucoma surgeries, dermal fat graft procedures, limbal stem cell expansion and retinal surgeries. The present review explores the latest scientific and clinical data, current challenges, and main prospects of this technology for the treatment of several ocular injuries.

Effects of topical Coenzyme Q10, Xanthan Gum and Sodium Hyaluronate on corneal epithelial wound healing

Clinical Relevance: Effective treatment of corneal epithelial defects is crucial to prevent secondary infectious keratitis and visual impairment due to loss of corneal transparency. Therefore, it is important to determine the effect of different topical agents on corneal wound healing response.Background: The aim was to compare the effects of three different eye drops on corneal epithelial wound healing in an experimental model.Methods: Twenty-four eyes of 24 female BALB/c mice were included. A 2 mm central corneal epithelial defect was created. Topical Coenzyme Q10 + Vitamin E D-α-TPGS 4 × 1 was applied to Group A (n = 6), topical Sodium hyaluronate + Xanthan Gum + 0.3% Nethylmicine 4 × 1 to Group B (n = 6) and topical Sodium hyaluronate 4 × 1 to Group C (n = 6). Group D (n = 6) was the control group without treatment. Clinical scoring according to corneal fluorescein staining and histopathological evaluations was performed.Results: Clinical scores according to corneal fluorescein staining were similar in all groups on days 1 (p = 0.05), 2 (p = 0.15) and 3 (p = 0.62). Electron microscopy revealed disruption of intercellular junctions between corneal epithelial cells and intracellular vacuole formation in all groups except Group A. Corneal epithelial thickness and superficial epithelial microvillus arrangement were close to normal in Group A.Conclusion: Although there was no difference in clinical scores between groups, electron microscopy revealed a better organised epithelium with normal configuration of microvilli and less vacuolisation in Group A.

Allogenic platelet-rich plasma in induced ulcers in rat’s cornea

ABSTRACT The objective in this study was to evaluate the clinic effect of applying allogenic platelet-rich plasma (PRP) heated or not, for treating cornea ulcers, including the dosage of PDGF-BB in the cornea. The ulcers were induced, standardizing the left eye from 81 rats (Ratus norvegicus, albinus variety), assigned randomly into three groups (N=27): control group (CG) which did not receive any topic treatment; heated PRP group (GA) and PRP group (GP), which received topical treatment every eight hours for five days. Each group underwent evaluation at 24 hours (M1), three days (M3) and five days (M5). The clinical exam evaluated the opacity, vascularization and corneal repair. The corneal PDGF-BB was dosed through the ELISA method. The corneal opacity was decreased in PRP-treated animals (GA and GP) and corneal repair time reduced when compared to CG at M1 and M5. Furthermore, GP showed greater vascularization at M3 compared to M1. Applied allogenic PRP eye drops, heated or not, speed up corneal healing, and reduce corneal repair time. However, the corneal PDGF concentration was not altered in any of the treatments.

Tryptophan as a Safe Compound in Topical Ophthalmic Medications: In Vitro and In Vivo Studies

Background: To evaluate the effects of tryptophan (TRP) on normal human corneal and conjunctival epithelium in vitro and the re-epithelization of corneal erosion in rabbits.Materials and methods: Corneal epithelial cell (10.014 pRSV-T) and conjunctival epithelial cell (HC0597) cultures were used. The cellular metabolism, viability, secretion of IL-1β, IL-6, IL-10, cytoskeleton organization, transwell migration were determined. Cells were incubated in the presence of TRP at 1-100 μM. After corneal de-epithelization rabbits received TRP drops (100 μM), 5 times a day.Results: TRP increased conjunctival epithelium metabolism at 50 μM and increased the viability of corneal epithelium at 100 μM. TRP (10 μM) enhanced the production of IL-6 by the corneal epithelium and had no effect on IL-1β and IL-10.Conclusions: TRP had no influence on the cellular cytoskeleton but induced a significant pseudopodia projection in both epithelia. TRP did not influence corneal re-epithelization in vivo. TRP was not toxic for corneal and conjunctival epithelia.

Plasma Rich in Growth Factors Enhances Cell Survival after in Situ Retinal Degeneration

PURPOSE

The purpose of this study was to examine the effect of plasma rich in growth factors (PRGFs) under blue light conditions in an in vivo model of retinal degeneration.

METHODS

Male Wistar rats were exposed to dark/blue light conditions for 9 days. On day 7, right eyes were injected with saline and left eyes with PRGF. Electroretinography (ERG) and intraocular pressure (IoP) measurements were performed before and after the experiment. After sacrifice, retinal samples were collected. Hematoxylin and eosin staining was performed to analyze the structure of retinal sections. Immunofluorescence for brain-specific homeobox/POU domain protein 3A (Brn3a), choline acetyltransferase (ChAT), rhodopsin, heme oxygenase-1 (HO-1), and glial fibrillary acidic protein (GFAP) was performed to study the retinal conditions.

RESULTS

Retinal signaling measured by ERG was reduced by blue light and recovered with PRGF; however, IoP measurements did not show significant differences among treatments. Blue light reduced the expression for Brn3a, ChAT, and rhodopsin. Treatment with PRGF showed a recovery in their expressions. HO-1 and GFAP results showed that blue light increased their expression but the use of PRGF reduced the effect of light.

CONCLUSIONS

Blue light causes retinal degeneration. PRGF mitigated the injury, restoring the functionality of these cells and maintaining the tissue integrity.

Expansion of Human Limbal Epithelial Stem/Progenitor Cells Using Different Human Sera: A Multivariate Statistical Analysis

Transplantation of human cultured limbal epithelial stem/progenitor cells (LESCs) has demonstrated to restore the integrity and functionality of the corneal surface in about 76% of patients with limbal stem cell deficiency. However, there are different protocols for the expansion of LESCs, and many of them use xenogeneic products, being a risk for the patients’ health. We compared the culture of limbal explants on the denuded amniotic membrane in the culture medium—supplemental hormone epithelial medium (SHEM)—supplemented with FBS or two differently produced human sera. Cell morphology, cell size, cell growth rate, and the expression level of differentiation and putative stem cell markers were examined. Several bioactive molecules were quantified in the human sera. In a novel approach, we performed a multivariate statistical analysis of data to investigate the culture factors, such as differently expressed molecules of human sera that specifically influence the cell phenotype. Our results showed that limbal cells cultured with human sera grew faster and contained similar amounts of small-sized cells, higher expression of the protein p63α, and lower of cytokeratin K12 than FBS cultures, thus, maintaining the stem/progenitor phenotype of LESCs. Furthermore, the multivariate analysis provided much data to better understand the obtaining of different cell phenotypes as a consequence of the use of different culture methodologies or different culture components.

Antioxidant Role of PRGF on RPE Cells after Blue Light Insult as a Therapy for Neurodegenerative Diseases

Oxidative stress has a strong impact on the development of retinal diseases such as age-related macular degeneration (AMD). Plasma rich in growth factors (PRGF) is a novel therapeutic approach in ophthalmological pathologies. The aim of this study was to analyze the antioxidant effect of PRGF in retinal epithelial cells (EPR) in in vitro and ex vivo retinal phototoxicity models. In vitro analyses were performed on ARPE19 human cell line. Viability and mitochondrial status were assessed in order to test the primary effects of PRGF. GSH level, and protein and gene expression of the main antioxidant pathway (Keap1, Nrf2, GCL, HO-1, and NQO1) were also studied. Ex vivo analyses were performed on rat RPE, and HO-1 and Nrf2 gene and protein expression were evaluated. The results show that PRGF reduces light insult by stimulating the cell response against oxidative damage and modulates the antioxidant pathway. We conclude that PRGF’s protective effect could prove useful as a new therapy for treating neurodegenerative disorders such as AMD.

Therapeutic effects of three human-derived materials in a mouse corneal alkali burn model

Purpose: To compare the therapeutic effects of human derivatives in a mouse alkali burn model. Methods: The right eyes of mice were injured using NaOH. After alkali injury, one of the following agents was topically administered for 7 d: human amniotic membrane (hAM) suspension, human umbilical cord serum (hUCS), and human peripheral blood serum (hPBS), or saline. The epithelial defect areas on days 1, 2, and 3 degrees of opacity on days 2, 3, and 7, and corneal neovascularization (NV) areas on day 7 were evaluated. Histologic examination and mRNA expression levels of tumour necrosis factor (TNF)-α, interleukin (IL)-6, vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, MMP-8, and MMP-9 were also evaluated on day 7. Results: The epithelial defect areas in the hUCS group were smaller than those in the control and hPBS groups on day 3 (p < .05, respectively). The epithelial defect areas in the hAM suspension group showed smaller than those in the control and hPBS groups on days 1 and 2 (p < .05, respectively). The degrees of opacity were lower in all treatment groups than that of the saline control group on day 7 (p < .05, respectively). Corneal NV areas were not different among groups on day 7 (p = 0.20). The expression levels of TNF-α, IL-6, MMP-8, and MMP-9 mRNA and the infiltration of the inflammatory cells in all treatment groups were lesser than those in the control group on day 7 (p< .05, respectively). Conclusions: All treatments reduced inflammatory reactions and corneal opacity development. Corneal reepithelialization was faster in the hUCS group.

Hyaluronic Acid Combined with Serum Rich in Growth Factors in Corneal Epithelial Defects

The aim of this study is to assess if an adhesive biopolymer, sodium hyaluronate (NaHA), has synergistic effects with s-PRGF (a serum derived from plasma rich in growth factors and a blood derivative that has already shown efficacy in corneal epithelial wound healing), to reduce time of healing or posology. In vitro proliferation and migration studies, both in human corneal epithelial (HCE) cells and in rabbit primary corneal epithelial (RPCE) cultures, were carried out. In addition, we performed studies of corneal wound healing in vivo in rabbits treated with s-PRGF, NaHA, or the combination of both. We performed immunohistochemistry techniques (CK3, CK15, Ki67, ß4 integrin, ZO-1, α-SMA) in rabbit corneas 7 and 30 days after a surgically induced epithelial defect. In vitro results show that the combination of NaHA and s-PRGF offers the worst proliferation rates in both HCE and RPCE cells. Addition of NaHA to s-PRGF diminishes the re-epithelializing capability of s-PRGF. In vivo, all treatments, given twice a day, showed equivalent efficacy in corneal epithelial healing. We conclude that the combined use of s-PRGF and HaNA as an adhesive biopolymer does not improve the efficacy of s-PRGF alone in the wound healing of corneal epithelial defects.

Emerging Approaches for Ocular Surface Regeneration

Purpose of review

In this manuscript, the recent advancements and novel approaches for regeneration of the ocular surface are summarized.

Recent findings

Following severe injuries, persistent inflammation can alter the rehabilitative capability of the ocular surface environment. Limbal stem cell deficiency (LSCD) is one of the most characterized ocular surface disorders mediated by deficiency and/or dysfunction of the limbal epithelial stem cells (LESCs) located in the limbal niche. Currently, the most advanced approach for revitalizing the ocular surface and limbal niche is based on transplantation of limbal tissues harboring LESCs. Emerging approaches have focused on restoring the ocular surface microenvironment using (1) cell-based therapies including cells with capabilities to support the LESCs and modulate the inflammation, e.g., mesenchymal stem cells (MSCs), (2) bio-active extracellular matrices from decellularized tissues, and/or purified/synthetic molecules to regenerate the microenvironment structure, and (3) soluble cytokine/growth factor cocktails to revive the signaling pathways.

Summary

Ocular surface/limbal environment revitalization provide promising approaches for regeneration of the ocular surface.

Strategies for reconstructing the limbal stem cell niche

The epithelial cell layer that covers the surface of the cornea provides a protective barrier while maintaining corneal transparency. The rapid and effective turnover of these epithelial cells depends, in part, on the limbal epithelial stem cells (LESCs) located in a specialized microenvironment known as the limbal niche. Many disorders affecting the regeneration of the corneal epithelium are related to deficiency and/or dysfunction of LESCs and the limbal niche. Current approaches for regenerating the corneal epithelium following significant injuries such as burns and inflammatory attacks are primarily aimed at repopulating the LESCs. This review summarizes and assesses the clinical feasibility and efficacy of current and emerging approaches for reconstruction of the limbal niche. In particular, the application of mesenchymal stem cells along with appropriate biological scaffolds appear to be promising strategies for long-term revitalization of the limbal niche.

Differential profile of protein expression on human keratocytes treated with autologous serum and plasma rich in growth factors (PRGF)

Purpose

The main objective of this study is to compare the protein expression of human keratocytes treated with Plasma rich in growth factors (PRGF) or autologous serum (AS) and previously induced to myofibroblast by TGF-β1 treatment.

Methods

Blood from healthy donor was collected and processed to obtain AS and PRGF eye drops. Blood derivates were aliquoted and stored at -80°C until use. Keratocyte cells were pretreated for 60 minutes with 2.5 ng/ml TGF-β1. After that, cells were treated with PRGF, AS or with TGF-β1 (control). To characterize the proteins deregulated after PRGF and AS treatment, a proteomic approach that combines 1D-SDS–PAGE approach followed by LC–MS/MS was carried out.

Results

Results show a catalogue of key proteins in close contact with a myofibroblastic differentiated phenotype in AS treated-cells, whereas PRGF-treated cells show attenuation on this phenotype. The number of proteins downregulated after PRGF treatment or upregulated in AS-treated cells suggest a close relationship between AS-treated cells and cytoskeletal functions. On the other hand, proteins upregulated after PRGF-treatment or downregulated in AS-treated cells reveal a greater association with processes such as protein synthesis, proliferation and cellular motility.

Conclusion

This proteomic analysis helps to understand the molecular events underlying AS and PRGF-driven tissue regeneration processes, providing new evidence that comes along with the modulation of TGF-β1 activity and the reversion of the myofibroblastic phenotype by PRGF.

Effects of 20% Human Serum on Corneal Epithelial Toxicity Induced by Benzalkonium Chloride: In Vitro and Clinical Studies

PURPOSE

Benzalkonium chloride (BAK), the most commonly used preservative in ophthalmic solutions, is known to cause toxicity in the corneal epithelium. In this study, we investigated the effects of 20% human serum in cultures of BAK-damaged human corneal epithelial cells (hCECs) and in patients with toxic corneal epitheliopathy induced by BAK-containing eye drops.

METHODS

hCECs were exposed to various concentrations of BAK (0%, 0.002%, 0.02%, and 0.2%) in the presence or absence of 20% human serum. After 24 hours, the metabolic activity, proliferation, apoptosis, and proinflammatory cytokine expression were evaluated in the cells. Also, cell migration was assessed using a scratch test. In the clinical study, 24 patients with toxic corneal epitheliopathy secondary to BAK-containing antiglaucoma eye drops were treated with topical application of 20% autologous serum, and corneal epithelial integrity was evaluated.

RESULTS

BAK induced cytotoxicity in hCECs by inhibiting the metabolic activity, proliferation, and migration and by increasing apoptosis in a concentration-dependent manner. The level of proinflammatory cytokine IL-8 was elevated in BAK-treated cells. Addition of 20% human serum to the cultures significantly promoted the cell metabolic activity, proliferation, and migration while markedly reducing apoptosis. In line with the in vitro results, corneal punctate epithelial erosions were decreased from a National Eye Institute scale score of 4.2 ± 2.1 to 1.3 ± 1.7 in 20 of 24 patients (84%) after treatment with 20% autologous serum.

CONCLUSIONS

Data demonstrate that 20% human serum is effective in treating BAK-induced cytotoxicity in hCECs and provides a basis for using 20% autologous serum for patients with preservative-induced corneal epitheliopathy.

Plasma rich in growth factors eye drops to treat secondary ocular surface disorders in patients with glaucoma

Purpose

To evaluate the efficacy and safety of plasma rich in growth factors (PRGF) eye drops in patients with glaucoma with secondary ocular surface disorders (OSDs) due to surgeries and topical hypotensive drugs use.

Materials and methods

A retrospective case-series study design was used including six patients (eight eyes) diagnosed with glaucoma who received surgical (nonpenetrating deep sclerectomy and/or trabeculectomy) and medical treatments (hypotensive eye drops) to control intraocular pressure (IOP) and who developed secondary OSDs, unresponsive to conventional treatments. Patients were treated with PRGF eye drops (four times a day). Outcome measures were ocular surface disease index (OSDI), best-corrected visual acuity (BCVA, in logarithm of the minimum angle of resolution), visual analog scale (VAS), frequency and severity of symptoms, and IOP. The safety of the treatment was also evaluated.

Results

Six patients (seven eyes with open-angle glaucoma and one eye with uveitic glaucoma) treated with PRGF eye drops were evaluated. Mean age was 71 years (SD=7.2, range 58–79 years). Five were female and one was male. The mean treatment time was 21.8 weeks (SD=9.0, range 12–36 weeks). The mean time to reach closure of the corneal ulcer was 14.5 (SD=5.5) weeks. A statistical significant reduction in OSDI scale (50.6%), VAS frequency (53.1%), VAS severity (42.0%), and a 41.8% improvement in BCVA were observed (p<0.05). IOP also decreased by 16.6% (p=0.010). Only one of the six patients reported itching in both eyes as an adverse event (AE); however, the patient continued with the PRGF eye drops until the end of therapy; the remaining patients did not report any AEs during the follow-up period.

Conclusions

In patients with glaucoma and secondary OSDs refractive to conventional treatments, the treatment with PRGF eye drops could be considered a possible therapeutic option, because it demonstrates an improvement in the signs and symptoms of the ocular surface, as well as a better control of the IOP. This is an initial research work that can open doors for future research to confirm these findings.

Serum from plasma rich in growth factors regenerates rabbit corneas by promoting cell proliferation, migration, differentiation, adhesion and limbal stemness

PURPOSE

To evaluate the regenerating potential and the mechanisms through which the autologous serum derived from plasma rich in growth factors (s-PRGF) favours corneal wound healing in vitro and in vivo.

METHODS

We compared the effect of various concentrations of s-PRGF versus fetal bovine serum (FBS) and control treatment in rabbit primary corneal epithelial and stromal cells and wounded rabbit corneas. Cell proliferation was measured using an enzymatic colorimetric assay. In vitro and in vivo wound-healing progression was assessed by image-analysis software. Migration and invasion were evaluated using transfilter assays. Histological structure was analysed in stained sections. Protein expression was evaluated by immunohistochemistry.

RESULTS

s-PRGF promoted the robust proliferation of epithelial cultures at any concentration, similar to FBS. Likewise, s-PRGF and FBS produced similar re-epithelialization rates in in vitro wound-healing assays. In vivo, s-PRGF treatment accelerated corneal wound healing in comparison with control treatment. This difference was significant only for 100% s-PRGF treatment in our healthy rabbit model. Histological analysis confirmed normal epithelialization in all cases. Immunohistochemistry showed a higher expression of cytokeratins 3/76 and 15, zonula occludens-1 and alpha-smooth muscle actin proteins as a function of s-PRGF concentration. Notably, keratocyte density in the anterior third of the stroma increased with increase in s-PRGF concentration, suggesting an in vivo chemotactic effect of s-PRGF on keratocytes that was further confirmed in vitro.

CONCLUSION

s-PRGF promotes proliferation and migration and influences limbal stemness, adhesion and fibrosis during corneal healing.

Autologous method for ex vivo expansion of human limbal epithelial progenitor cells based on plasma rich in growth factors technology

PURPOSE

Develop an autologous culture method for ex vivo expansion of human limbal epithelial progenitor cells (LEPCs) using Plasma Rich in Growth Factors (PRGF) as a growth supplement and as a scaffold for the culture of LEPCs.

METHODS

LEPCs were cultivated in different media supplemented with 10% fetal bovine serum (FBS) or 10% PRGF. The outgrowths, total number of cells, colony forming efficiency (CFE), morphology and immunocytochemistry against p63- α and cytokeratins 3 and 12 (CK3-CK12) were analyzed. PRGF was also used to elaborate a fibrin membrane. The effects of the scaffold on the preservation of stemness and the phenotypic characterization of LEPCs were investigated through analysis of CK3-CK12, ABCG-2 and p63.

RESULTS

LEPCs cultivated with PRGF showed a significantly higher growth area than FBS cultures. Moreover, the number of cells were also higher in PRGF than FBS, while displaying a better morphology overall. CFE was found to be also higher in PRGF groups compared to FBS, and the p63-α expression also differed between groups. LEPCs cultivated on PRGF membranes appeared as a confluent monolayer of cells and still retained p63 and ABCG-2 expression, being negative for CK3-CK12.

CONCLUSIONS

PRGF can be used in corneal tissue engineering, supplementing the culture media, even in a basal media without any other additives, as well as providing a scaffold for the culture.

Platelet rich plasma in ocular surface

The use of platelet-rich preparations has experienced a significant increase in recent years due to its role in tissue-repair and regeneration. The aim of this study is to examine the available evidence regarding the application of plasma rich in growth factors, and its variations, on the ocular surface. A review is also presented on the effects of platelet-derived growth factors, the implications of the preparation methods, and the existing literature on the safety and efficacy of these therapies in ocular surface diseases. Despite the widespread use of platelet preparations there is no consensus on the most appropriate preparation method, and growth factors concentration vary with different systems. These preparations have been used in the treatment of ocular surface diseases, such as dry eye or persistent epithelial defects, among others, with good safety and efficacy profiles, but further studies are needed to compare to the currently available alternatives.

Treatment of severe chronic ocular graft-versus-host disease using 100% autologous serum eye drops from a sealed manufacturing system: a retrospective cohort study

BACKGROUND/AIMS

To analyse patients with chronic ocular graft-versus-host disease (GvHD) under treatment with 100% autologous serum eye drops from a sealed manufacturing system.

METHODS

17 patients with chronic ocular GvHD received 100% autologous serum eye drops from single use vials manufactured in a sealed system. Retrospective analysis included visual acuity, corneal staining, frequency of artificial tears, ocular symptoms by means of a questionnaire and information on subjective side effects and cost compensation.

RESULTS

Data of prior to autologous serum eye drops therapy and at a 6-month follow-up were obtained. They demonstrated a significant increase in visual acuity (logMAR oculus dexter/right eye (OD) 0.5±0.32 to 0.4±0.3; oculus sinister/left eye (OS) 0.6±0.35 to 0.3±0.35; p=0.177/0.003) and significant improvement in corneal staining (Oxford grading scheme: OD from 3±1.03 to 2±1.43, OS from 4±1.0 to 2±1.09, p=0.004/0.001) and ocular symptoms (ocular surface disease index: 88±20.59 to 63±22.77; p=0.02). Frequency of artificial tears was reduced and no side effects were reported. Patient satisfaction was 100%, and cost compensation by health insurance reached 80%.

CONCLUSIONS

100% autologous serum eye drops using a sealed manufacturing system were efficient in improving the ocular surface, patient symptoms and visual acuity without side effects. It seems to be safe to use 100% autologous serum despite earlier suspicions regarding immune complex accumulations and exacerbation of ocular surface inflammation. The potential effects of serum levels of systemic immunosuppressives through readministration onto the ocular surface need to be elucidated.

Plasma Rich in Growth Factors for the Treatment of Ocular Surface Diseases

PURPOSE

The purpose of this work is to describe and review the technology of plasma rich in growth factors (PRGF), a novel blood derivative product, in the treatment of ocular surface disorders.

METHODS

To demonstrate the importance of this technology in the treatment of ocular pathologies, a thorough review of the preclinical and clinical literature results obtained following use of the different therapeutic formulations of PRGF was carried out. A literature search for applications of PGRF plasma in the ophthalmology field was carried out using the PubMed database.

RESULTS

PRGF involves the use of patient's own biologically active proteins, growth factors, and biomaterial scaffolds for therapeutic purposes. This procedural technology is gaining interest in regenerative medicine due to its potential to stimulate and accelerate the tissue healing processes. The versatility and biocompatibility of this technology opens the door to a personalized medicine on ocular tissue regeneration. This review discusses the state of the art of the new treatments and technologies developed to promote ocular surface tissue regeneration. The standardized protocol that has been developed to source eye drops from PRGF technology is also described. The preclinical research, together with the most relevant clinical applications are summarized and discussed.

CONCLUSIONS

The preliminary results suggest that the use of PRGF to enhance ocular tissue regeneration is safe and efficient.

Stability of limbal stem cell deficiency after mechanical and thermal injuries in mice

We studied the reproducibility and stability of limbal stem cell deficiency (LSCD) in mice following controlled injuries to the corneal and limbal epithelia. In one method, corneal and limbal epithelia were entirely removed with a 0.5 mm metal burr. In the other, limbus to limbus epithelial removal with the burr was followed by thermal injury to the limbus. These two methods were compared with a previously published one. Unwounded corneas were used as control. The corneas were examined monthly for three months by slit lamp with fluorescein staining. Immunofluorescence staining for cytokeratin 12 and 8 on corneal wholemount and cross sections were performed to determine the phenotype of the epithelium. Mechanical shaving of the epithelium, with or without thermal injury, resulted in a reproducible state of LSCD marked by superficial neovascularization, reduce of keratin 12 expression and presence of goblet cells on the cornea. The phenotype was stable in 100% of the eyes up to at least three months. Thermal injury produced a more severe phenotype with more significant stromal opacification. These corneal injury models may be useful for studying the mechanisms leading to limbal stem cell deficiency.

Plasma rich in growth factors (PRGF) eye drops stimulates scarless regeneration compared to autologous serum in the ocular surface stromal fibroblasts

Autologous serum (AS) eye drops was the first blood-derived product used for the treatment of corneal pathologies but nowadays PRGF arises as a novel interesting alternative to this type of diseases. The purpose of this study was to evaluate and compare the biological outcomes of autologous serum eye drops or Plasma rich in growth factors (PRGF) eye drops on corneal stromal keratocytes (HK) and conjunctival fibroblasts (HConF). To address this, blood from healthy donors was collected and processed to obtain autologous serum (AS) eye drops and plasma rich in growth factors (PRGF) eye drops. Blood-derivates were aliquoted and stored at -80°C until use. PDGF-AB, VEGF, EGF, FGFb and TGF-β1 were quantified. The potential of PRGF and AS in promoting wound healing was evaluated by means of proliferation and migration assays in HK and HConF. Fibroblast cells were induced to myofibroblast differentiation after treatment with 2.5ng/mL of TGF-β1. The capability of PRGF and AS to prevent and inhibit TGF-β1-induced differentiation was evaluated. Results showed significant higher levels of all growth factors analyzed in PRGF eye drops compared to AS. Moreover, PRGF eye drops enhanced significantly the biological outcomes of both HK and HConF, and reduced TGF-β1-induced myofibroblast differentiation in contrast to autologous serum eye drops (AS). In summary, these results suggest that PRGF exerts enhanced biological outcomes than AS. PRGF may improve the treatment of ocular surface wound healing minimizing the scar formation compared to AS. Results obtained herein suggest that PRGF protects and reverses the myofibroblast phenotype while promotes cell proliferation and migration.