Albumin as a tear supplement in the treatment of severe dry eye

The Plight of the Metabolite: Oxidative Stress and Tear Film Destabilisation Evident in Ocular Allergy Sufferers across Seasons in Victoria, Australia

Ocular allergy (OA) is characterised by ocular surface itchiness, redness, and inflammation in response to allergen exposure. The primary aim of this study was to assess differences in the human tear metabolome and lipidome between OA and healthy controls (HCs) across peak allergy (spring-summer) and off-peak (autumn-winter) seasons in Victoria, Australia. A total of 19 participants (14 OA, 5 HCs) aged 18-45 were recruited and grouped by allergy questionnaire score. Metabolites and lipids from tear samples were analysed using mass spectrometry. Data were analysed using TraceFinder and Metaboanalyst. Metabolomics analysis showed 12 differentially expressed (DE) metabolites between those with OA and the HCs during the peak allergy season, and 24 DE metabolites were found in the off-peak season. The expression of niacinamide was upregulated in OA sufferers vs. HCs across both seasons (p ≤ 0.05). A total of 6 DE lipids were DE between those with OA and the HCs during the peak season, and 24 were DE in the off-peak season. Dysregulated metabolites affected oxidative stress, inflammation, and homeostasis across seasons, suggesting a link between OA-associated itch and ocular surface damage via eye rubbing. Tear lipidome changes were minimal between but suggested tear film destabilisation and thinning. Such metabolipodome findings may pave new and exciting ways for effective diagnostics and therapeutics for OA sufferers in the future.

New advances in medical management of dry eye: optimizing treatment strategies for enhanced relief

PURPOSE

Dry eye disease (DED) is a prevalent ocular surface disease that is conventionally characterized by tear film hyperosmolarity and instability. This review presents a summarized classification of DED, followed by a comprehensive discussion of the most recent topical and systemic medications and clinical recommendations for selecting the most appropriate option for each patient.

METHODS

An extensive literature search was conducted on electronic databases, such as PubMed, Scopus, and Web of Science, using keywords including "dry eye syndrome," "ocular surface disease," "medical management," "artificial tears," "topical immunomodulators," and "meibomian gland dysfunction."

RESULTS

The underlying reasons for DED can range from insufficient aqueous tear production to increased tear evaporation. Recent literature has provided a more in-depth understanding of the pathophysiology of DED by examining the tear film's lipid, aqueous, and mucin layers. However, despite these advancements, medical management of patients with symptomatic DED has not fully reflected this modernized knowledge of its pathophysiology.

CONCLUSION

To develop a rationalized strategy for treating DED, it is crucial to have updated knowledge of therapeutic options, their mechanisms of actions, and indications based on the DED type and underlying causes.

[Comparison of the Effect of Autologous Serum on Therapy Resistant Corneal Erosions and Ulcers on the Corneal Graft vs. the Patient's Own Cornea]

PURPOSE

The aim of this study is to compare the healing of corneal epithelial defects or ulcers on the corneal graft in comparison with the patient's own cornea after treatment with 100%, undiluted autologous serum eye drops.

METHODS

In a retrospective study over 7 years, we analysed 263 treatments with autologous serum eye drops of persistent corneal epithelial defects (erosions [88%] vs. ulcers [12%]). We compared the epithelial healing tendency of patients with defects on their own cornea (51.9%) vs. patients who had previously undergone penetrating keratoplasty (48.1%). Complete epithelial healing during the 28 days of treatment was considered as therapeutic success. In addition, the recurrence rate of the epithelial defects after finishing the therapy was analysed.

RESULTS

88.2% of the epithelial defects healed during 28 days of therapy. The recurrence rate during follow-up was 5.1%. There was no significant difference with respect to success rate between corneal defects on the patient's own cornea (87.8%) and on the graft (88.6%; p = 0.137). There was a significantly lower success rate for corneal ulcers (74.2%) than for erosions (90.3%; p < 0.001). The recurrence rate of erosions was 4.4%, vs. 4.3% in ulcers during follow-up.

CONCLUSION

The results of our study suggest that autologous serum eye drops are a non-invasive and safe alternative treatment for persistent corneal epithelial defects - with no significant difference in patients with a defect on their own cornea vs. defects on the corneal graft. The success rate, but not the recurrence rate, is significantly worse in ulcers than in erosions.

Neuropathic Corneal Pain as Debilitating Manifestation of LONG-COVID

This report illustrates the case of a female patient suffering from severe ocular discomfort, tinnitus and ageusia, 7 months after a SARS-CoV-2 infection. The medical history implicated a diagnosis of LONG-COVID with ocular pain as the most debilitating symptom. In-vivo confocal microscopy revealed corneal microneuromas with hyperreflectivity and irregular enlargement of nerve endings in both eyes, which led to the diagnosis of neuropathic corneal pain. The aim of this report is to increase awareness that COVID-19 induced neuropathic pain can also occur in the cornea representing the human body's most richly innervated tissue.

Current trends in pharmaceutical treatment of Dry Eye Disease: A review

Dry eye disease (DED), keratoconjunctivitis sicca or dysfunctional tear syndrome, is the most prevalent ophthalmic disease which affects a substantial segment of people worldwide with increasing frequency. It is considered a multifactorial disease of the ocular surface and tear film, characterized by a variation of signs and symptoms. The symptoms range from mild to severe itching, burning, irritation, eye fatigue, and ocular inflammation that may lead to potential damage to the cornea, conjunctiva and even vision loss. Correspondingly, depending on the different manifestations and pathophysiology, the treatment must be tailored specifically to each patient by targeting the specific mechanisms implicated in their disease. Currently, there are several medical products and techniques available or under investigation for the treatment of DED. The present article focused on the pathophysiology of DED, the new diagnostic approach and the recently developed drug delivery systems or devices reducing the progress of the disease and treating the causes.

A Review of Emerging Tear Proteomics Research on the Ocular Surface in Ocular Allergy

Ocular allergy is an immunoglobulin E-mediated Type I hypersensitivity reaction localised to the ocular surface and surrounding tissues. Primary signs and symptoms of ocular allergy include itching, redness, irritation and inflammation. Eye-rubbing caused by itching has been shown to alter ocular surface protein concentrations in conditions linked to ocular allergy such as keratoconus. In keratoconus, the cornea begins to thin and sag over time, leading to progressive vision loss and blindness in severe conditions. Due to the high incidence of ocular allergy sufferers rubbing their eyes in response to symptoms of itching, the protein landscape of the ocular surface may be significantly altered. Differential protein expression caused by long-term inflammation and eye-rubbing may lead to subsequent changes in ocular surface structure and function over time. This review aims to summarise and explore the findings of current ocular allergy proteome research conducted using techniques such as gel electrophoresis, mass spectrometry and lab-on-a-chip proteomics. Proteins of interest for this review include differentially expressed immunoglobulins, mucins, functional proteins, enzymes and proteins with previously uncharacterised roles in ocular allergy. Additionally, potential applications of this research are addressed in terms of diagnostics, drug development and future research prospects.

A review on albumin as a biomaterial for ocular drug delivery

Development of ocular drug delivery system is one of the most technically challenging tasks, when compared with other routes of drug delivery. Eye (an intricate organ) is highly sophisticated and sensitive organ due to presence of various structurally differed anatomical layers, which many times limits the drug delivery approaches. Despite several limitations, many advancements have been made as evidence from various recent studies involving improvement of both residence time and permeation of the drug at the ocular region. In the last few decades, albumin(s) based ophthalmic products have been gained most attention to solve the major challenges associated with conventional ocular drug delivery systems. Interestingly, an albumin-based micro, nano, conjugates, and genetically fused target specific to ligand(s) formulation being exploited through many studies for successful ocular delivery of bioactives (mostly repurposed drugs). Past and current studies suggested that albumin(s) based ocular drug delivery system is multifunctional in nature and capable of extending both drug residence time and sustaining the release of drugs to deliver desired pharmacological outcomes. Despite wide applications, still complete progress made in albumin based ocular drug delivery is limited in literature and missing in market. So, herein we presented an overview to explore the key concepts of albumin-based nanocarrier(s) including strategies involved in the treatment of ocular disease, that have yet to be explored.

Autologous serum eye drops for ocular surface disorders

PURPOSE OF REVIEW

Ocular surface disease is a prevalent, diverse group of conditions that cause patient discomfort and decreased visual acuity and present considerable expense to both patients and healthcare systems. Autologous serum eye drops are a topical treatment modality derived from the patient's own blood. Use of serum eye drops for ocular surface disease has been promising due to biochemical similarities to endogenous tears.

RECENT FINDINGS

Use of serum eye drops for moderate to severe ocular surface diseases such as dry eye, corneal epithelial defects, and inflammatory conditions has become more prevalent. Recent studies have demonstrated that the use of serum eye drops is well-tolerated by patients and associated with improvement in patient-reported outcomes and objective dry eye parameters. Production of serum eye drops may vary, treatment costs can be significant, and the quality of evidence for serum eye drop use published from randomized controlled trials is modest, particularly for long-term treatment. Accessibility remains an area for improvement and may be complemented by allogeneic serum eye drops.

SUMMARY

Serum eye drops are frequently used as a safe, well-tolerated, and effective treatment for ocular surface disease. Further research is needed to assess long-term outcomes and improve accessibility.

Albumin Acts as a Lubricant on the Surface of Hydrogel and Silicone Hydrogel Contact Lenses

Feeling comfortable is the greatest concern for contact lens wearers, and it has been suggested that in vivo comfort could be corresponded to the in vitro friction coefficient of contact lenses. How tear albumin could affect the friction coefficient of silicone hydrogel and hydrogel contact lenses was analyzed by sliding a lens against a quartz glass in normal and extremely high concentration of albumin solution. Albumin deposition testing and surface roughness analysis were also conducted. The results showed that the friction coefficient of tested contact lenses did not correspond to both the albumin deposition amount and surface roughness, but we proposed a model of how albumin might act as a lubricant on the surface of some hydrogel and silicone hydrogel contact lenses. In conclusion, albumin provided lubrication for silicone hydrogel contact lenses regardless of albumin concentrations, while albumin only acted as a lubricant for hydrogel contact under normal concentration.

Impact of diurnal variation, sex, tear collection method, and disease state on tear protein levels in dogs

OBJECTIVE

To investigate the effects of various biological factors on total protein concentration (TPC) and serum albumin levels in canine tears.

ANIMALS STUDIED

10 healthy beagles (5 female, 5 male) were used.

PROCEDURES

Experiments were conducted on separate days, collecting tears with either capillary tubes or Schirmer strips, as follows: (i) Tear collection at 3 hours intervals (from 6 am to 12 am); and (ii) Tear collection before and 20 minutes following topical histamine application (1, 10, 375 mg/mL) to induce mild, moderate, and severe conjunctivitis, respectively. TPC and serum albumin were measured with infrared spectroscopy and ELISA, respectively.

RESULTS

Tear film TPC and serum albumin ranged from 9.7-26.1 mg/mL and 6.4-1662.6 µg/mL, respectively. Protein levels did not differ significantly among time points (P ≥ .080). Median coefficient of variation (CV%) was lower with Schirmer strips compared to capillary tubes for both TPC (12% vs 15%, P = .020) and serum albumin (57% vs 78%, P = .232). TPC (P < .001), but not serum albumin was greater in male vs. female dogs. Serum albumin, but not TPC (P ≥ .099), increased significantly with each grade of conjunctivitis severity (P < .001), with no differences between collection devices (P ≥ .322); median increase was 106%, 1389%, and 2871% in eyes with mild, moderate, and severe conjunctivitis, respectively.

CONCLUSIONS

There is no apparent diurnal variation in canine tear protein levels. Blood-tear barrier breakdown with conjunctivitis allows serum albumin to leak into the tear film at high concentrations. Schirmer strips compare well with capillary tubes for bioanalytical purposes in healthy and diseased eyes, and this collection method may offer improved reproducibility for protein quantification.

Albumin Levels in Tear Film Modulate the Bioavailability of Medically-Relevant Topical Drugs

The breakdown of blood-tear barrier that occurs with ocular pathology allows for large amounts of albumin to leak into the tear fluid. This process likely represents an important restriction to drug absorption in ophthalmology, as only the unbound drug is transported across the ocular tissue barriers to exert its pharmacologic effect. We aimed to investigate the effects of albumin levels in tears on the bioavailability of two commonly used ophthalmic drugs: tropicamide, an antimuscarinic that produces mydriasis and cycloplegia, and latanoprost, a PGF2α analog used for the treatment of glaucoma. Eight female beagle dogs underwent a randomized, vehicle-controlled crossover trial. For each dog, one eye received 30 µl of artificial tears (control) or canine albumin (0.4 or 1.5%) at random, immediately followed by 30 µl of 1% tropicamide (2 days, 24 h washout) or 0.005% latanoprost (2 days, 72 h washout) in both eyes. Pupil diameter (digital caliper) and intraocular pressure (IOP; rebound tonometry) were recorded at various times following drug administration (0 to 480 min) and compared between both groups with a mixed model for repeated measures. Albumin in tears had a significant impact on pupillary diameter for both tropicamide (P ≤ 0.001) and latanoprost (P ≤ 0.047), with no differences noted between 0.4% and 1.5% concentrations. Reduction in the maximal effect (pupil size) and overall drug exposure (area under the effect time-curve of pupil size over time) were significant for tropicamide (6.2–8.5% on average, P ≤ 0.006) but not for latanoprost (P ≥ 0.663). The IOP, only measured in eyes receiving latanoprost, was not significantly impacted by the addition of either 0.4% (P = 0.242) or 1.5% albumin (P = 0.879). Albumin in tear film, previously shown to leak from the conjunctival vasculature in diseased eyes, may bind to topically administered drugs and reduces their intraocular penetration and bioavailability. Further investigations in clinical patients and other commonly used ophthalmic medications are warranted.

Development of New Pharmaceutical Candidates With Antioxidant Activity for the Treatment of Corneal Disorders

The ocular surface is continuously exposed to physical and chemical factors in the environment. Oxidative stress, which strongly affects the ocular surface, is caused by several factors, including ultraviolet irradiation, fine particles, and tobacco smoke. Oxidative stress is one of the pathogeneses for corneal disorders. Thus, corneal epithelium and tear fluid contain antioxidants and antioxidative enzymes to protect the cornea against oxidative stress. Because autologous serum eye drops are useful for the treatment of corneal disorders caused by dry eye, these eye drops are globally used as a therapeutic intervention in patients with dry eye. We investigated the serum components that exert antioxidative effects to clarify the mechanism of action for serum antioxidants on corneal epithelial cells and to apply these components as drugs for the treatment of corneal disorders. We found that selenoprotein P, a known selenium-transfer plasma glycoprotein, was secreted into the tear fluid to supply the corneal epithelium with selenium. Selenium participates in the regulation of oxidative stress in many tissues, including the cornea. We subsequently developed selenium compounds for application in eye drops and successfully prepared Se-COMP as a new candidate for the treatment of corneal disorders.

Advances in Functional Restoration of the Lacrimal Glands

The lacrimal glands produce tears to support a healthy homeostatic environment on the ocular surface. The lacrimal gland dysfunction characteristic of dry eye disease causes ocular discomfort and visual disturbances and in severe cases can result in a loss of vision. The demand for adequate restoration of lacrimal gland function has been intensified due to advances in stem cell biology, developmental biology, and bioengineering technologies. In addition to conventional therapies, including artificial tears, tear alternatives (such as autologous serum eye drops) and salivary gland transplantation, a regenerative medicine approach has been identified as a novel strategy to restore the function of the lacrimal gland. Recent studies have demonstrated the potential of progenitor cell injection therapy to repair the tissue of the lacrimal glands. A current three-dimensional (3D) tissue engineering technique has been shown to regenerate a secretory gland structure by reproducing reciprocal epithelial-mesenchymal interactions during ontogenesis in vitro and in vivo. A novel direct reprogramming method has suggested a possibility to induce markers in the lacrimal gland developmental process from human pluripotent stem cells. The development of this method is supported by advances in our understanding of gene expression and regulatory networks involved in the development and differentiation of the lacrimal glands. Engineering science has proposed a medical device to stimulate tearing and a bio-hybrid scaffold to reconstruct the 3D lacrimal gland structure. In this review, we will summarize recent bioengineering advances in lacrimal gland regeneration toward the functional restoration of the lacrimal glands as a future dry eye therapy.

Evaluation of lacrimal production, osmolarity, crystallization, proteomic profile, and biochemistry of capuchin monkeys' tear film

BACKGROUND

To evaluate the composition and characteristics of capuchin monkey (CM) tear film.

METHODS

Eleven CM (Sapajus sp.) was evaluated. Strip meniscometry test (SMT), osmolarity, and tear ferning test (TFT) (by Rolando and Masmali scales) were assessed. Tear protein profile (SDS-PAGE), and total protein, albumin, urea, glucose, and cholesterol levels in tear film and blood serum were screened.

RESULTS

Median ± semi-interquatil range for SMT and osmolarity values were 8.0 ± 1.625 and 303.0 ± 9.875, respectively. TFT for Rolando was 2.0 ± 0.5, and Masmali was 2.0 ± 0.0. Monkeys's tear obtained type II and III for Rolando, and 1 and 2 for Masmali. Tear components showed protein bands among 23-217 kDa, and presence of albumin, urea, glucose, and cholesterol.

CONCLUSIONS

The results of SMT, osmolarity, TFT, SDS-PAGE, and tear biochemistry may serve as a reference baseline for CM, and the data may serve as a basis for future experimental model evaluations.

Reflections on Dry Eye Syndrome Treatment: Therapeutic Role of Blood Products

Dry eye syndrome (DES) is a multifactorial, frequent, pathology characterized by deficient tear production or increased evaporation of tears and associated with ocular surface alteration and inflammation. It mostly affects, but not exclusively, older individuals and leads to varying degrees of discomfort and decreased quality of life. Although the typical treatments of DES rely on using artificial tears, polyunsaturated fatty acids, integrin antagonists, anti-inflammatory agents, or on performing punctal occlusion, recently, standardized blood-derived serum eye drops (SED) are generating much interest as a new physiological treatment option. The scientific rationale in using SED for treating or releasing the symptoms of DES is thought to lie in its composition in multiple factors that resembles that of tears and contributes to the healing and protection of the ocular surface. This manuscript seeks to provide relevant background information on the management of DES, and on the increasing role that various types of SED or platelet lysates, from autologous or allogeneic origins, are playing in the improved therapeutic management of this pathology. The increasing role played by blood establishments in producing better-standardized SED is also addressed.

Identification of transcription factors that promote the differentiation of human pluripotent stem cells into lacrimal gland epithelium-like cells

Dry eye disease is the most prevalent pathological condition in aging eyes. One potential therapeutic strategy is the transplantation of lacrimal glands, generated in vitro from pluripotent stem cells such as human embryonic stem cells, into patients. One of the preceding requirements is a method to differentiate human embryonic stem cells into lacrimal gland epithelium cells. As the first step for this approach, this study aims to identify a set of transcription factors whose overexpression can promote the differentiation of human embryonic stem cells into lacrimal gland epithelium-like cells. We performed microarray analyses of lacrimal glands and lacrimal glands-related organs obtained from mouse embryos and adults, and identified transcription factors enriched in lacrimal gland epithelium cells. We then transfected synthetic messenger RNAs encoding human orthologues of these transcription factors into human embryonic stem cells and examined whether the human embryonic stem cells differentiate into lacrimal gland epithelium-like cells by assessing cell morphology and marker gene expression. The microarray analysis of lacrimal glands tissues identified 16 transcription factors that were enriched in lacrimal gland epithelium cells. We focused on three of the transcription factors, because they are expressed in other glands such as salivary glands and are also known to be involved in the development of lacrimal glands. We tested the overexpression of various combinations of the three transcription factors and PAX6, which is an indispensable gene for lacrimal glands development, in human embryonic stem cells. Combining PAX6, SIX1, and FOXC1 caused significant changes in morphology, i.e., elongated cell shape and increased expression (both RNAs and proteins) of epithelial markers such as cytokeratin15, branching morphogenesis markers such as BARX2, and lacrimal glands markers such as aquaporin5 and lactoferrin. We identified a set of transcription factors enriched in lacrimal gland epithelium cells and demonstrated that the simultaneous overexpression of these transcription factors can differentiate human embryonic stem cells into lacrimal gland epithelium-like cells. This study suggests the possibility of lacrimal glands regeneration from human pluripotent stem cells.

Dysfunctional tear syndrome: dry eye disease and associated tear film disorders - new strategies for diagnosis and treatment

Dysfunctional tear syndrome (DTS) is a common and complex condition affecting the ocular surface. The health and normal functioning of the ocular surface is dependent on a stable and sufficient tear film. Clinician awareness of conditions affecting the ocular surface has increased in recent years because of expanded research and the publication of diagnosis and treatment guidelines pertaining to disorders resulting in DTS, including the Delphi panel treatment recommendations for DTS (2006), the International Dry Eye Workshop (DEWS) (2007), the Meibomian Gland Dysfunction (MGD) Workshop (2011), and the updated Preferred Practice Pattern guidelines from the American Academy of Ophthalmology pertaining to dry eye and blepharitis (2013). Since the publication of the existing guidelines, new diagnostic techniques and treatment options that provide an opportunity for better management of patients have become available. Clinicians are now able to access a wealth of information that can help them obtain a differential diagnosis and treatment approach for patients presenting with DTS. This review provides a practical and directed approach to the diagnosis and treatment of patients with DTS, emphasizing treatment that is tailored to the specific disease subtype as well as the severity of the condition.

Quality standards, safety and efficacy of blood-derived serum eye drops: A review

Serum eye drops (SEDs) are being used increasingly to treat dry eye syndrome and persistent corneal epithelial defects, and are usually prescribed when conventional treatments fail. SEDs are commonly sourced from the patient's own blood via an autologous collection. Although SEDs are clearly beneficial, they are not available for those patients that cannot donate sufficient blood, and some centres are moving to allogeneic SEDs. Many studies have reported that both allogeneic and autologous SEDs are effective. However, few large randomised controlled trials have been conducted to date, and clinical evidence is therefore limited to smaller studies. Alternatives to serum are also being explored, such as platelet lysate and products made from platelet rich plasma, as they are a rich source of growth factors. This article reviews how some centres are approaching allogeneic collections for SEDs, and alternatives to serum that are currently being explored.

Challenges and Strategies for Regenerating the Lacrimal Gland

The lacrimal gland produces the aqueous component of tears, including electrolytes, peptides, and glycoproteins necessary to maintain homeostasis and optical properties of the ocular surface. Stem cells that contribute to the homeostasis of the lacrimal gland are under extensive study. It is still unclear whether such stem cells are of mesenchymal or epithelial origin. It is also possible that a unique epithelial stem cell undergoes epithelial-mesenchymal transition and contributes to the mesenchyme. Developmental studies in mice have shown that a network of growth factors contributes to epithelial-mesenchymal interaction during morphogenesis of the lacrimal gland. Recently, the developmental process was successfully recapitulated in vitro, providing a valuable tool for study of lacrimal gland development and possibly opening doors to regenerative therapy. While further studies are required to identify and appreciate the potential of lacrimal gland stem cells, advances in stem cell biology in general should become a catalyst towards developing regenerative therapy of the lacrimal gland.

Human albumin eye drops as a therapeutic option for the management of keratoconjunctivitis sicca secondary to chronic graft-versus-host disease after stem-cell allografting

BACKGROUND

Keratoconjunctivitis sicca from chronic graft-versus-host disease (cgvhd) after allogeneic stem cell transplantation is common, leading to severe corneal damage and blindness if not treated. We retrospectively examined the efficacy and safety of pooled human albumin eye drops (haeds) for symptom relief in 40 stem-cell transplantation patients after other alternatives had failed.

METHODS

The Common Terminology Criteria for Adverse Events (version 4.0) and the cgvhd grading scale were used to compare response in the patients during January 2000 and July 2013. In addition, on days 1 and 30, the haeds were subjected to quality assurance testing for sterility, oncotic pressure, albumin measurement, viscosity, pH, and purity by protein electrophoresis.

RESULTS

Use of haeds resulted in symptom relief for 37 patients (92.5%); 3 patients (7.5%) failed to improve with use of haeds (p ≤ 0.0001). Of the 37 patients having symptom relief, 7 (19%) improved from grade 3 to no dry eye symptoms. Proportionately, post-treatment symptom improvement by two grade levels, from 3 to 1 (70%), was significantly higher than improvement by one grade level, from 3 to 2 (11%) or from 2 to 1 (19%, p ≤ 0.0001). Time to symptom relief ranged from 2 weeks to 28 weeks. Of the 40 patients, 38 (95%) had no adverse reactions. Days 1 and 30 quality assurance testing results were equivalent.

CONCLUSIONS

Complications of keratoconjunctivitis sicca were well managed and well tolerated with haeds when other remedies failed. Quality assurance testing confirmed that haeds were safe and stable in extreme conditions.

Autologous serum and plasma rich in growth factors in ophthalmology: preclinical and clinical studies

The use of blood derivatives represents an alternative therapeutic approach that is gaining interest in regenerative medicine due to its potential to stimulate and accelerate tissue healing. Autologous serum eye drops and platelet-enriched plasma eye drops are being used in the treatment of different ophthalmological disorders. In this review, we summarize the different blood-derived formulations used in the treatment and care of ocular surface disorders. The biological basis and use of autologous serum and plasma rich in growth factors are deeply evaluated as well as the challenges to be addressed in the future in this new generation of blood-derived therapies.

Ischemia preconditioning protects rat submandibular glands from ischemia/reperfusion injuries

To investigate the effects of ischemia/reperfusion on rat submandibular glands without denervation and the possible protective effects of ischemia preconditioning on the glands that experienced ischemia/reperfusion, in-situ ischemia/reperfusion and ischemia preconditioning experimental models of submandibular glands of healthy male Wistar rats were conducted. For ischemia/reperfusion groups, the glands were subjected to 90 min of ischemia without denervation, followed by 1, 12, 24, or 72 h of reperfusion. Ischemia preconditioning was achieved by 3 min of ischemia following 3 min of reperfusion, performed three times before ischemia/reperfusion. Salivary secretion, histological changes, alterations of tight junctions, myeloperoxidase activity, cellular apoptosis, and reactive oxygen species levels were detected. In ischemia/reperfusion glands, rising acute-inflammation responses, reduced tight-junction width, and increased myeloperoxidase activity, reactive oxygen species levels, and apoptotic cell numbers were observed, along with secretory dysfunction, especially at 1 and 12 h post-reperfusion, which seemed to gradually return to normal by 72 h post-reperfusion. In contrast, ischemia preconditioning showed the potential to ameliorate the injury-stress responses caused by ischemia/reperfusion. Our study revealed that ischemia/reperfusion could cause a series of injury-stress responses and ultimately lead to hyposecretion, independently of the parasympathetic nerve supply, which might play an important role in the early-phase dysfunction of the transplanted glands. Ischemia preconditioning could protect the involved glands and improve ischemia/reperfusion-induced hyposecretion.

Bioengineered Lacrimal Gland Organ Regeneration in Vivo

The lacrimal gland plays an important role in maintaining a homeostatic environment for healthy ocular surfaces via tear secretion. Dry eye disease, which is caused by lacrimal gland dysfunction, is one of the most prevalent eye disorders and causes ocular discomfort, significant visual disturbances, and a reduced quality of life. Current therapies for dry eye disease, including artificial tear eye drops, are transient and palliative. The lacrimal gland, which consists of acini, ducts, and myoepithelial cells, develops from its organ germ via reciprocal epithelial-mesenchymal interactions during embryogenesis. Lacrimal tissue stem cells have been identified for use in regenerative therapeutic approaches aimed at restoring lacrimal gland functions. Fully functional organ replacement, such as for tooth and hair follicles, has also been developed via a novel three-dimensional stem cell manipulation, designated the Organ Germ Method, as a next-generation regenerative medicine. Recently, we successfully developed fully functional bioengineered lacrimal gland replacements after transplanting a bioengineered organ germ using this method. This study represented a significant advance in potential lacrimal gland organ replacement as a novel regenerative therapy for dry eye disease. In this review, we will summarize recent progress in lacrimal regeneration research and the development of bioengineered lacrimal gland organ replacement therapy.

Ophthalmic use of blood-derived products

There is a wide spectrum of blood-derived products that have been used in many different medical and surgical specialties with success. Blood-derived products for clinical use can be extracted from autologous or allogeneic specimens of blood, but recombinant products are also commonly used. A number of blood derivatives have been used for a wide range of ocular conditions, from the ocular surface to the retina. With stringent preparation guidelines, the potential risk of transmission of blood-borne diseases is minimized. We review blood-derived products and how they are improving the management of ocular disease.

The application of autologous serum eye drops in severe dry eye patients; subjective and objective parameters before and after treatment

AIM

To assess the impact of autologous serum (AS) eye drops on the ocular surface of patients with bilateral severe dry eye and to draw a comparison between the clinical and laboratory examinations and the degree of subjective symptoms before and after serum treatment.

MATERIALS AND METHODS

A three-month prospective study was conducted on 17 patients with severe dry eye. AS eye drops were applied a maximum of 12 times a day together with regular therapy. Dry eye status was evaluated by clinical examination (visual acuity, Schirmer test, tear film breakup time, vital staining, tear film debris and meniscus), conjunctival impression cytology (epithelial and goblet cell density, snake-like chromatin, HLA-DR-positive and apoptotic cells) and subjectively by the patients.

RESULTS

The application of AS eye drops led to a significant improvement in the Schirmer test (p < 0.01) and tear film debris (p < 0.05). The densities of goblet (p < 0.0001) and epithelial cells (p < 0.05) were significantly increased, indicating a decrease of squamous metaplasia after AS treatment. A significant decrease (p < 0.05) was found in the number of apoptotic, HLA-DR-positive and snake-like chromatin cells on the ocular surface. A significant improvement was found in all evaluated subjective symptoms. Altogether, the clinical results were improved in 77%, the laboratory results in 75% and the subjective feelings in 63% of the eyes.

CONCLUSIONS

We found that three-month AS treatment led especially to the improvement of ocular surface dryness and damage of the epithelium. The improvement of dry eye after AS treatment correlated well with the clinical, laboratory and subjective findings. From the patients' subjective point of view, the positive effect of AS decreased with time, but still persisted up to three months after the end of therapy.

[Effectiveness of topical autologous serum treatment in neurotrophic keratopathy]

OBJECTIVE

To evaluate the effectiveness of 20% autologous serum as a treatment for neurotrophic keratopathy.

MATERIAL AND METHODS

A longitudinal, observational and descriptive study was performed on 19 patients (22 eyes) with neurotrophic keratopathy in different stages of Mackie's classification. The following variables were evaluated on the first visit, and then 4 months later: best corrected visual acuity (BCVA), subjective patient symptomatology (faces scale), Schirmer's test without anesthesia (mm), tear film break-up time (BUT) (sg) and healing of the epithelial defect (weeks). The Wilcoxon signed-rank test was used for the statistical analysis of the data.

RESULTS

A symptomatic improvement was observed in 100% of the cases, and a 71% improvement in best corrected visual acuity (P<.05). There was also a statistically significant improvement in the Schirmer's test and BUT (P<.05). Healing of epithelial defect occurred in 71% of the cases within 6 weeks, and in 91% of the cases within 12 weeks of treatment. The remaining 9% of the cases that did not heal had a grade 3 neurotrophic keratopathy.

CONCLUSIONS

The use of 20% autologous topical serum represents an effective treatment for grades 1 and 2 neurotrophic keratopathy, but is an insufficient treatment for a grade 3 keratopathy. In cases where there is a significant loss of tissue, the application of a higher concentration of autologous serum, or platelet-rich derivatives, or plasma rich in growth factors, may be more effective than the application of 20% autologous serum, due to their greater effect on cell proliferation.

Clinical trials of therapeutic ocular surface medium for moderate to severe dry eye

PURPOSE

To investigate therapeutic ocular surface medium (TOSM), a potential physiological tear replacement therapy, for moderate to severe dry eye.

METHODS

Forty-six patients with symptoms of moderate to severe dry eye despite maximal standard therapy were enrolled in a prospective pilot study of TOSM over 1 month (n = 10) and a randomized, double-masked, controlled trial of TOSM versus saline (placebo) over 2 months (n = 36). The primary outcome measure was conjunctival rose bengal staining.

RESULTS

An improvement in conjunctival rose bengal staining by ≥3 points occurred in 7 of 10 patients receiving TOSM in the pilot study (P = 0.017) and in 8 of 18 patients (44%) in the randomized trial (P = 0.982). In the pilot study, subjective dry eye symptoms significantly improved (P = 0.005). TOSM significantly improved the blepharitis score (P = 0.002) and conjunctival impression cytology (P = 0.028) in the randomized controlled trial. There were no serious or irreversible side effects with TOSM.

CONCLUSIONS

TOSM is a physiological tear replacement for dry eye that, unlike autologous serum, can be easily manufactured, could be widely available, and may also be beneficial for blepharitis.

Pharmacotherapy of dry eye

INTRODUCTION

based on data from the largest studies of dry eye to date - the Women's Health Study (WHS) and the Physicians' Health Study (PHS) - and other studies, it has been estimated that about 3.23 million women and 1.68 million men, for a total of 4.91 million Americans aged ≥ 50 years, have dry eye. Tens of millions more have less severe symptoms and probably a more episodic manifestation of the disease that is notable only during contact with some adverse contributing factor(s), such as low humidity or contact lens wear. Dry eye disease is a common yet frequently under-recognized public health problem whose etiology and management challenge clinicians and researchers involved in this field.

AREAS COVERED

advances in the understanding of the disease have been made over the past 10 years in areas of epidemiology, pathogenesis, clinical manifestation, and possible therapy. Historical aspects and recent information in relation to the use of artificial tear substitutes and anti-inflammatory agents in dry eye disease, including topical cyclosporin and corticosteroids, autologous serum, tetracyclines and systemic immunosuppressants, are covered in this review. The reader will gain insight into the recent views on the pharmacological menu of treatments for dry eyes following the recommendations of the 2007 International Dry Eye Workshop.

EXPERT OPINION

dry eye is a visually disabling disease, the treatment of which needs tailoring according to the type and severity of dry eye disease.

Long-term follow-up after submandibular gland transplantation in severe dry eyes secondary to cicatrizing conjunctivitis

PURPOSE

To evaluate the long-term results of autologous submandibular gland transplantation in eyes with cicatrizing conjunctivitis and to determine biomechanical and biochemical features of the resulting salivary tear film.

DESIGN

Prospective, observational case series.

METHODS

Fifteen eyes with cicatrizing conjunctivitis with a viable autologous submandibular gland transplantation were compared with 10 eyes with cicatrizing conjunctivitis and a failed submandibular gland transplantation or no submandibular gland transplantation. Best-corrected visual acuity, frequency of tear substitute instillation, severity of dry eye discomfort, lid margin erythema, conjunctival hyperemia, corneal epithelial edema, tear film break-up time, Schirmer test results, and corneal fluorescein and conjunctival Rose Bengal staining were evaluated. In a subgroup central corneal thickness and sensitivity, corneal epithelial barrier function, conjunctival and lid margin flora, and conjunctival impression cytologic analysis results were evaluated. In 3 patients, preoperative and postoperative tear samples were analyzed for viscosity, surface tension, and presence of mucins.

RESULTS

Submandibular gland autotransplantation resulted in long-term improvement of subjective, objective, and some ocular surface parameters. Salivary mucins were detectable in salivary tears after submandibular gland transplantation. The viscosity of salivary tears was more similar to normal saliva and the surface tension was intermediate between the 2 original secretions.

CONCLUSIONS

Submandibular gland autotransplantation provides long-term relief from pain and reduces the need for frequent installation of lubricants.

Selenoprotein P controls oxidative stress in cornea

The ocular surface is always attacked by oxidative stress, and cornea epithelial cells are supposed to have their own recovery system against oxidative stress. Therefore we hypothesized that tears supply key molecules for preventing oxidative stress in cornea. The potential target key molecule we focused is selenoprotein P (SeP). SeP is a carrier of selenium, which is an essential trace element for many animals, for oxidative stress metabolism in the organism, and was extremely expressed in lacrimal gland. An experiment was performed with SeP eye drops in a rat dry eye model, prepared by removing the lacrimal glands. The anticipated improvement in corneal dry eye index and the suppression of oxidative stress markers were observed in SeP eye drop group. Furthermore, the concentration of SeP was significantly higher in dry eye patients compared with normal volunteers. Collectively, we concluded that tear SeP is a key molecule to protect the ocular surface cells against environmental oxidative stress.

Managing a child with an external ocular disease

Children are affected by some common external diseases, including allergic conjunctivitis and blepharokeratoconjunctivitis. This workshop aims to familiarize readers with the clinical features of each along with common presentations and to discuss strategies for managing these conditions, with emphasis on newer drugs and therapies. The other group of external diseases that commonly present in children comprises persistent punctate erosions and persistent epithelial defects. Etiology is varied, and making the correct diagnosis requires a systematic approach with close inspection of the microenvironment of the eye. Common causes and treatment modalities will be discussed. Types of lubrication and how they may best be used also will be outlined.

Still confused about rose bengal?

We have surveyed the ophthalmic literature of the last five years in an attempt to evaluate the use and usefulness of Rose Bengal staining as an aid to differential diagnosis in dry eyes. Included both as a criterion and as an adjunct measure of disease progression, Rose Bengal scores of patients with different dry eye conditions overlap, sometimes to a considerable extent. A mechanistic link between staining with this dye and disease etiology is unlikely; however, Rose Bengal could be a surrogate marker of changes in ocular surface physiology. The question whether the extent and pattern of staining with Rose Bengal provide the clinician with information not available from other tests, and in particular from fluorescein staining of the ocular surface, has to be answered positively, though the nature of this information is not clearly understood. A more widespread recognition that Rose Bengal is not a vital dye is necessary in order not to bias the interpretation of experimental results.

Serum eye drops, amniotic membrane and limbal epithelial stem cells--tools in the treatment of ocular surface disease

The advent of serum eye drops, amniotic membrane and limbal stem cell grafts, have transformed the treatment of diseases which result in ocular surface failure. This article provides an overview of ocular surface anatomy and failure, and how the use of serum eye drops, amniotic membrane and limbal epithelial stem cell transplantation has influenced ophthalmological practice both historically and in recent years. This review focuses on the rationale for the use of these emerging tools, how they are prepared, clinical applications, limitations, and speculates on future directions.

Albumin rescues ocular epithelial cells from cell death in dry eye

PURPOSE

Because autologous serum is useful for the treatment of severe dry eye, serum components may be a potential candidate for the treatment of dry eye. Serum albumin is abundantly contained in human serum and plays many physiologic roles. We investigated the efficacy of serum albumin in a dry eye animal model.

METHODS

Sprague-Dawley rats were used to make dry eye model rats according to a previous study. The central region of the corneal epithelium was scraped mechanically, and the rats were placed in a desiccation room (temperature, 23 +/- 2 degrees C; humidity, 28 +/- 2%; air flow, 2-4 m/s) for 12 hr. During desiccation, one eye of each rat was treated with human serum albumin eye drops, and the other eye was given a drop of phosphate buffered saline (PBS). Human corneal and conjunctival cell lines were used to investigate suppression effect of albumin on apoptosis induced by addition of apoptosis inducers or serum deprivation, respectively.

RESULTS

The erosion area was increased by 12 hr of desiccation. Albumin treatment decreased the area of erosion compared with PBS treatment. Apoptosis suppression assay using cell lines revealed that caspase-3 activation induced by serum deprivation and DNA fragmentation induced by addition of apoptosis inducers were dose-dependently suppressed by albumin.

CONCLUSIONS

Albumin showed a therapeutic effect in dry eye model rats. This efficacy may be related to the suppression of apoptosis by albumin.

Recent advances in the management of ocular complications of Sjögren's syndrome

Sjögren's syndrome (SS) is an autoimmune disorder, the principal ocular manifestation of which is decreased tear production leading to chronic irritation and damage to the corneal and conjunctival epithelium. The most important advance in the treatment of ocular manifestations of SS is the introduction of topical anti-inflammatory agents such as cyclosporine A, which increases tear production and decreases symptoms without any significant side effect. Stimulators of tear secretion, both topical, such as diquafosol, and systemic, such as pilocarpine and cevimeline, are also effective, although they have been associated with frequent side effects. Topical use of autologous serum is another new and effective form of treatment, but problems in the preparations prevent their widespread use. Additionally, nonpharmacologic treatments, such as insertion of punctal plugs, are beneficial in the dry eye of SS, whereas several other modalities, such as anti-CD4 monoclonal antibody eye drops and gene transfer, are still in experimental phases.

Dry eye: diagnosis and current treatment strategies

One in four patients attending ophthalmic clinics report symptoms of dry eye, making it one of the most common complaints seen by ophthalmologists. Aqueous-layer deficiency is the most common form of dry eye and is frequently caused by decreased secretion of tears by the lacrimal glands. Evaporative dry eye is often secondary to meibomian gland disease and results in a defective lipid layer. Tear replacement or preservation using artificial tears and/or punctal occlusion are the mainstay of treatment. Newer forms of therapy were designed to modify the underlying disease process. These include the use of topical cyclosporin A, autologous serum, and sodium hyaluronate drops, which suppress underlying inflammation, provide growth factors, and prevent the onset of squamous metaplasia in ocular surface epithelium. Hormonal therapy might have a role in the future of dry eye therapy.

Differential effects of serum constituents on apoptosis induced by the cyclopentenone prostaglandin 15-deoxy-delta12,14-prostaglandin J2 in WISH epithelial cells

Cyclopentenone prostaglandins, delta12-PGJ2 and 15d-PGJ2, have potent anti-tumour and anti-inflammatory activities, and have been shown to induce apoptosis in amnion-derived WISH cells. In this study, we have investigated the protective effects of serum and its constituents (growth factors and albumin) on delta12-PGJ2 and 15d-PGJ2-induced apoptosis in WISH cells. Serum (0.5% w/v) was protective against both delta12-PGJ2 and 15d-PGJ2-induced apoptosis. This was not due to the presence of serum-derived growth factors (EGF, IGF-1 and IGF-2), since they had no significant effect on 15d-PGJ2-induced cell death. In contrast, IGF-1 partially inhibited etoposide-induced apoptosis, confirming the presence of a functional IGF-1 receptor signalling system. Albumin was identified as the key survival factor in serum, since albumin and delipidated albumin exhibited the same level of protection from 15d-PGJ2-induced apoptosis as serum itself. The potential for serum albumin to regulate the bioactivity of cyclopentenone PGs may be of considerable importance in pathological conditions where roles for cyclopentenone PGs have been identified.