[Experimental evaluation of the efficacy of tissue-engineered constructs in the treatment of limbal stem cell deficiency]. / Eksperimental'naya otsenka effektivnosti primeneniya tkaneinzhenernoi konstruktsii v lechenii limbal'noi nedostatochnosti.

Limbal stem cell deficiency (LSCD) is one of the leading factors negatively affecting the success of keratoplasty, and its treatment remains an urgent problem in ophthalmology. With the development of regenerative medicine, one of the promising approaches is the transplantation of tissue-engineered constructs from cultured limbal stem cells (LSCs) in biopolymer carriers. PURPOSE: This study was conducted to develop an experimental model of LSCD and evaluate the effectiveness of transplantation of a tissue-engineered construct consisting of cultured cells containing a population of LSCs and a collagen carrier. MATERIAL AND METHODS: The study was performed on 12 rabbits and included several stages. At the first stage, the physiological effects of collagen matrix implantation into the limbal zone were studied. At the second stage, tissue-engineered constructs consisting of LSCs on a collagen matrix were formed and their effect on the regeneration processes in the experimental LSCD model was analyzed. The animals were divided into 2 groups: surgical treatment (transplantation of the tissue-engineered construct) was used in the experimental group, and conservative treatment was used in the control group. Slit-lamp biomicroscopy with photo-registration, fluorescein corneal staining, optical coherence tomography of the anterior segment of the eye, and impression cytology were used to assess the results. RESULTS: No side reactions were observed after implantation of the collagen matrix into the limbal zone. One month after surgical treatment of the LSCD model in the experimental group, complete epithelization with minor manifestations of epitheliopathy was observed. In the control group, erosion of the corneal epithelium was noted. The time of corneal epithelization in the experimental and control groups was 9.2±2.95 and 46.20±12.07 days, respectively (p=0.139). According to the data of impression cytology, in the experimental group there were no goblet cells in the central part of the cornea, which indicates the restoration of corneal type epithelial cells, in contrast to the control group. CONCLUSION: Transplantation of a tissue-engineered construct from cultured limbal cells on a collagen membrane should be considered as a promising method for the treatment of limbal stem cell deficiency.

[Dynamic pathomorphological characteristics of the nasolacrimal duct in its stenosis]. / Dinamicheskaya patomorfologicheskaya kharakteristika nososleznogo protoka pri ego stenozirovanii.

OBJECTIVE: Pathological description of the process of stenosis of the nasolacrimal duct at its various stages. MATERIAL AND METHODS: The material for the study was obtained from the wall of the nasolacrimal duct during surgery in 50 patients whose condition was attributed to the 1st, 2nd or 3rd clinical stage of dacryostenosis. The material was fixed in formalin and sent for pathohistological and immunohistochemical (IHC) studies. RESULTS: In the 1st stage, the integrity of the epithelium of the nasolacrimal duct was preserved, the density of goblet cells was reduced. Seromucinous glands were single in the lamina propria in the area of stenosis. Diffuse lymphoid-plasmacytic infiltration was observed along the periphery of the terminal sections of the glands and in the subepithelial zone. The infiltrate includes CD68+ tissue macrophages and CD20+ and CD3+ lymphocytes, with a predominance of B-lymphocytes over T-lymphocytes. In the 2nd stage, changes in the epithelial layer in the stenosis zone were detected. In the IHC study, only individual leukocytes were observed in these zones, and T cells were found mainly in the subepithelial zone, B cells - deeper, monocytes - evenly in all layers. In the adjacent zones, the picture of the infiltrate corresponded to the 1st stage. In the 3rd stage, fragments of the nasolacrimal duct wall were represented by dense fibrous connective tissue with pronounced atrophic changes, areas of squamous metaplasia or proliferation of the basal layer, goblet cells were not detected. There was no infiltrate in the area of stenosis during IHC study. In the cellular elements of the infiltrate in areas adjacent to the stenosis zone, CD20+ and CD3+ lymphocytes were present in equal proportions, the arrangement in layers corresponded to that of the 2nd stage. CONCLUSION: The results of the study showed that dacryostenosis is a progressive pathological process associated with the progredient development of chronic productive inflammation in the lacrimal ducts.

[Age prediction based on the examination of bone tissue elemental composition using energy dispersive X-Ray spectroscopy]. / Prognozirovanie vozrasta na osnovanii izucheniya elementnogo sostava kostnoi tkani s pomoshch'yu energodispersionnoi rentgenovskoi spektroskopii.

THE AIM OF THE STUDY: Was to assess the possibility of using chemical analysis of bone mineral content by the means of an energy dispersive X-Ray spectroscopy to determine the age of unidentified corpses for forensic identification. A semi-quantative chemical microanalysis of bone fragments of 85 male and female corpses aged between 21 and 91 was done through the use of energy dispersive X-Ray spectrometer. The association of bone tissue apatite mineral composition with age is confirmed and a formula, connecting age and chemical composition change, is proposed. The possibility of using quantitive evaluation of chemical elements content in the normative mineral to determine the unidentified corpse's age in a standard laboratory, equipped with an energy dispersive X-Ray spectrometer, was proved.

[Cell cultures - model object for experimental studies in ophthalmology]. / Kletochnye kul'tury ­ model'nyi ob"ekt dlya eksperimental'nykh issledovanii v oftal'mologii.

The article presents results obtained on several types of model cultures. Primary cultures of corneal epithelial cells and fibroblast-like cells from the limbus were obtained from the tissues of the anterior eye segment. Tests were performed on these cultures to determine the cytotoxicity of antiglaucoma drugs and to trial a protection method. In addition, a comparative analysis of the regenerative potential of various blood derivatives was carried out. An in vitro culture of endotheliocytes showed a correlation between the degree of damaging effects of antiglaucoma drugs of various groups and the content of the preservative benzalkonium chloride in their composition. Corneal keratocytes were used to create a cell sheet reflecting the main structural features of the stroma and suitable for biomechanical tests. The antifibrotic activity of the drugs was tested on the culture of fibroblasts from the nasolacrimal duct. The conducted studies demonstrate that cell cultures can be used as an informative model object for researching the pathogenesis of ophthalmic diseases and for testing drugs.

[Express-diagnosis of the diseases of the eye and its appendages by scanning electron microscopy with supravital staining]. / Skaniruyushchaya elektronnaya mikroskopiya s supravital'nym kontrastirovaniem v ekspress-diagnostike zabolevanii glaza i pridatochnogo apparata.

This review describes the history of development of a new line of chemical reagents that prompts to significantly reevaluate the application of scanning electron microscopy (SEM) in medical and biological studies, particularly in ophthalmology; considers the establishing of SEM as an analytical method; covers the problems in its application associated with the needs of clinical medicine and the complexities of biological sample preparation for electron microscopy. The article also presents in chronological order the technical solutions associated with creating a unique line of reagents for supravital staining. The multitude of technical solutions allows considering SEM as a method of express diagnostics. The review discusses examples of practical application of these methods for solving certain cases in clinical ophthalmology. The niche of SEM is considered among other methods of clinical diagnostics, as well as its future development involving the use of artificial intelligence.

[Visualization of normal ocular surface microflora via impression cytology sample using scanning electron microscopy with lanthanide contrasting]. / Vizualizatsiya normal'noi mikroflory glaznoi poverkhnosti posredstvom impressionnoi proby s ispol'zovaniem skaniruyushchego elektronnogo mikroskopa i lantanoidnogo kontrastirovaniya.

PURPOSE: To determine the possibilities of impression cytology (IC) with subsequent visualization of the sample on a scanning electron microscope in assessment of normal microflora of the ocular surface. MATERIALS AND METHODS: The article presents a visual characteristic of the microorganisms of the ocular surface (OS) captured during impression cytology (IC) in individuals without signs of inflammatory and degenerative eye diseases. The original method of staining the sample with heavy metal salts made it possible to identify the individual signs of the microorganisms in their subsequent visualization by scanning electron microscopy (SEM). RESULTS: The paper presents photomicrographs of the microorganisms most common for the OS obtained with the help of SEM, confirming and supplementing the data of non-visual methods of studying the ocular microflora. It was shown that the detection frequency of the microbial component of the OS by the visual method presented in this study is comparable with the detection frequency when using the microbial cultivation method (<80%). Coccoid and rod-shaped microorganisms were detected with relatively equal frequency, with the coccoid organisms mainly represented in association with epithelial cells. The morphological diversity of rod-shaped microorganisms is shown. CONCLUSION: The results of the study can be used as a visual reference for the normal microbiome of the eye.

[Mineral dysmetabolism in corneal diseases]. / Narusheniya mineral'nogo obmena pri zabolevaniyakh rogovitsy.

Functional status and biological properties of connective tissues significantly depend on the mineral elements involved in their metabolism. Connective tissue portion of the corneal stroma makes up most of its thickness; pathological changes in collagen fibers and the stroma can cause a range of corneal diseases, some of which are specifically associated with disorders of mineral metabolism. The article considers impairments of mineral metabolism as possible pathophysiological mechanisms in certain diseases and disorders of the cornea, and describes in detail the abnormalities associated with mineral dysmetabolism observed in patients with keratoconus.

[Evaluation of aqueous cytokine levels in eyes with Fuchs endothelial corneal dystrophy and bullous keratopathy]. / Opredelenie urovnya tsitokinov vo vnutriglaznoi zhidkosti pri endotelial'noi distrofii rogovitsy Fuksa i bulleznoi keratopatii.

PURPOSE: To evaluate cytokine levels in the aqueous humor (AH) of patients with Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK). MATERIAL AND METHODS: The study included 74 patients (74 eyes). The first group consisted of 31 patients (72.7±9.2 years) with FECD; the second group included 35 patients (72.4±9.1 years) with BK. The control group comprised 8 patients (74.3±4.1 years) with immature cataract. Before surgery, patients underwent pachymetry of the central cornea (RTvue-100 OCT, Optovue, USA). Patients of groups 1 and 2 underwent endothelial keratoplasty (DSAEK or DMEK), or penetrating corneal transplantation. Patients of the control group underwent phacoemulsification with implantation of intraocular lens. The initial stage of the surgery involved AH sample collection for evaluation of cytokine levels (IL-1ß, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12(p70), IL-13, IL-17, G-CSF, GM-CSF, IFNγ, MCP-1, MIP-1ß and TNF-α) by fluorescent flow cytometry using the Bio-Plex Pro Human Cytokine Panel, 17-plex (Bio-Rad, USA). RESULTS: Multiplex analysis of the AH content did not show any statistically significant differences in cytokine levels between decompensated FECD and BK eyes. The levels of IL-6, IL-8, GM-CSF, IFNγ, MCP-1, MIP-1ß were significantly elevated in FECD and BK eyes compared with healthy control. An insignificant deviation of IL-4 and IL-13 levels was detected in FECD and BK eyes compared with healthy controls. There were no significant differences in IL-1ß and TNF-α (indicators of acute inflammation) between the study groups. CONCLUSION: The obtained data confirm that FECD and BK are associated with disruption of ocular immune privilege that leads to chronic local inflammation, which in turn causes remodeling of the corneal tissues resulting in fibrosis.

Biomineralization of Trabecular Meshwork in Open-Angle Glaucoma.

A new form of open-angle glaucoma has been identified, in which calcification and silicification of the trabecular meshwork is a potentially significant component of outflow obstruction. It is noted that the mineralization of this area is promoted by various disturbances in the acid-base balance in the tissue. The role of melanosomal enzymes in the initiation of the formation of mineral calcium phosphate in trabecular tissue in open-angle glaucoma is considered.

[Accumulation of sulfur and phosphorus in the eye's drainage system in primary open-angle glaucoma]. / Nakoplenie sery i fosfora v drenazhnoi zone glaza pri pervichnoi otkrytougol'noi glaukome.

PURPOSE: To analyze the chemical composition of the sclera and trabecular meshwork in patients with primary open-angle glaucoma (POAG) and to assess the impact of corneal-compensated intraocular pressure (IOP) on the chemistry of the drainage area. MATERIAL AND METHODS: Biopsy specimens of the trabecular meshwork (89 specimens) and sclera (41 specimens) obtained from patients with POAG on maximal medical therapy were analyzed to determine the content of certain chemical elements - carbon (C), nitrogen (N), oxygen (O), aluminum (Al), calcium (Ca), chlorine (Cl), potassium (K), magnesium (Mg), sodium (Na), phosphorus (P), silicon (Si) and sulfur (S). The elements were selected based on chemical structure target tissue and sensitivity of the method used for analysis. Visualization was performed using the «EVO LS 10¼ (Zeiss, Germany) scanning electron microscope (SEM), and the chemical composition was studied with the «Oxford-X-MAX-50¼ (Oxford, UK) energy-dispersive spectrometer (EDS). Statistical analysis was performed using the Spearman correlation. RESULTS: The IOP of patients with POAG was found to have positive correlation with the total amount of S, P, and Ca in the trabecular meshwork. The accumulation of sulfur-containing compounds associated with pigment granules in trabecular meshwork's tissue was identified. A correlation was determined between the organic and inorganic (mineral) phosphorus content in the trabeculae, and the IOP values. The organic component of phosphorus was better represented than the mineral component in patients with increased IOP. CONCLUSION: In patients with POAG, an increase in the IOP level causes the amount of S associated with pigment granules and the proportion of organic P to increase in the trabecular meshwork, which should be taken into account in the further search for drug therapy that would potentially affect pathologically altered tissue.

[Modern biotechnological treatment methods of persistent corneal epithelial defects]. / Biotekhnologicheskie metody lecheniya persistiruyushchikh epitelial'nykh defektov rogovitsy.

The article reviews modern methods of treatment of persistent corneal epithelial defects and considers the factors involved in the development of this pathology, including the limbal stem cell deficiency, which is likely to play the main role. The most promising treatment methods are described, particularly the use of blood derivatives and cell therapy.

[Rational strategy for studying microbiome of the ocular surface of people using hard contact lenses by method of 16S rRNA gene metabarcoding]. / Ratsional'naya strategiya izucheniya mikrobioma glaznoi poverkhnosti pol'zovatelei zhestkikh kontaktnykh linz metodom metabarkodinga po genu 16S rRNK.

The study is based on the hypothesis that high taxonomic diversity of bacteria detectable on the eye surface by molecular genetic methods is attributed to the high level of its contamination by skin microflora. Such contamination would make it problematic to identify the fractions of real ocular surface microbiome, which remains behind the one-percent cut-off threshold adopted in the metagenomic analysis. Hard contact lenses for long-wearing act as a physical filter preventing DNA contamination from random microorganisms, and at the same time providing adhesion to the living cells of bacteria and fungi. To confirm this assumption, a detailed analysis of references was carried out, supplemented by original laboratory research. MATERIAL AND METHODS: The analysis included 16 hard contact lenses obtained from 11 patients with impaired refraction (myopia). Additionally, conjunctival mucosa scrapings were collected from 42 patients. Samples were cross-analyzed by 16S rRNA gene sequencing using 454 GS Junior (Ion Torrent) and Illumina MiSeq platforms. RESULTS: Results obtained by the Illumina platform (analysis of the V3-V4 variable region of the 16S rRNA gene) showed better convergence with the data of culture tests reported in the literature. The major microorganism groups found were: Acinetobacter (39%), Gluconacetobacter (10.8%), Propionibacterium (9.3%), Corynebacterium (9.3%), Staphylococcus (7.2%), Streptococcus (7%), Pseudomonas (4.1%), Micrococcus (3.3%), Yersinia (3%), Chondromyces (2.4%), Serratia (2.3%), and Bacillus (2.1%). Analysis of the samples obtained directly from the mucosa revealed dominance of typical skin-associated microorganisms. CONCLUSION: The present study proposes a contamination-reduction algorithm for microbiological testing of the ocular surface using hard contact lenses for prolonged wearing as a carrier for microbial DNA.

[Influence of fibrosis mediators on the outcomes of endoscopic endonasal dacryocystorhinostomy]. / Vliianie mediatorov fibroza na rezul'taty éndonazal'noi éndoskopicheskoi dakriotsistorinostomii.

INTRODUCTION: Fibrosis is the most important pathologic condition involved in undesirable outcomes of dacryocystorhinostomy. A number of biochemical factors are currently known to have an effect on wound healing by promoting excessive scarring. Isoforms of transforming growth factor ß (TGF-ß1) are considered the 'main' pro-fibrotic factor, but wound healing is also affected by other cytokines such as connective tissue growth factor (CTGF), which stimulates fibrosis, and fibroblast growth factor (FGF-2), which acts as antagonist to it. PURPOSE: To investigate correlations between endoscopic endonasal dacryocystorhinostomy outcomes and certain mediators of fibrosis. MATERIAL AND METHODS: The study included 45 cases of endoscopic endonasal dacryocystorhinostomy. The patients were grouped according to surgery outcome: patients with unsuccessful surgical treatment were assigned to group 1 (n=10); patients with successful surgical treatment - to group 2 (n=34). One patient was excluded from the study. Full-layer biopsy specimen were taken from patients' nasal mucosa before the surgery. TGF-ß1, TGF-ß2, TGF-ß3, CTGF, FGF-2 concentrations were evaluated using ELISA and normalized by total protein concentration. RESULTS: Surgical failure was observed in 10 cases (22.72%). CTGF concentration was significantly correlated with negative outcome (p<0.05) and was elevated in most specimen obtained from group 1. No significant correlation was noted between the concentrations of other evaluated cytokines in nasal mucosa specimens and the surgical outcome. CONCLUSION: The study found a correlation between CTGF concentration in nasal mucosa and dacryocystorhinostomy outcome, which supports the hypothesis suggested by several authors linking dacryocystorhinostomy failure with chronic inflammation in nasal mucosa.

[Polishing of Bowman's membrane with diamond burr in the treatment of recurrent corneal erosion syndrome]. / Abrazivnaia shlifovka boumenovoi membrany almaznym borom v lechenii retsidiviruiushchei érozii rogovitsy.

PURPOSE: To study the effectiveness of polishing Bowman's membrane with a diamond burr (DBPBM) in the treatment of recurrent corneal erosion syndrome (RCES). MATERIAL AND METHODS: The study included 22 patients (22 eyes) with RCES aged 20-56 years who underwent our original modification of DBPBM. All patients had keratotopography examined, endothelial cell density measured, and optical coherence tomography (OCT) of the cornea taken before and after the procedure. Additionally, conjunctival scraping, blood test for types I and II herpes (fluorescent antibody method) were performed before the surgery. Post-operative treatment included 1-2 weeks of anti-inflammatory and anti-bacterial steroid therapy, and 6 months of artificial tear Cationorm usage. RESULTS: Rehabilitation of all patients after the procedure went quickly, and no relapses were noted during the follow-up. Complete epithelialization of the area of surgical intervention under soft contact lens occurred over 2-3 days. Epithelial thickness was measured with OCT including epithelial mapping; after the surgery, it was almost even over the entire corneal surface. No complications such as induced post-operative refractive error or corneal haze were registered during the course of the study. Disruption of basal epithelial layer and epithelial basal membrane in the area of erosion relapse detected with scanning electron microscopy confirmed the need for their removal in the course of the surgery. CONCLUSION: Conservative treatment of RCES rarely yields results. Removal of inadequate epithelium and following DBPBM using our original method is a highly effective and accessible procedure for RCES treatment with low risk of complications and relapse.

[Methods of preserving donor corneas]. / Metody konservatsii donorskikh rogovits.

Corneal transplantation is the most successful and frequently performed allotransplantation procedure. Benign outcome of penetrating and posterior keratoplasty depends on viability of the corneal tissue and presence of the proper endothelial layer, which retaining is one of the main objectives of preservation of donor material. Methods designed to reach this goal may be classified according to storage duration as short-term (storage in a moist chamber), medium-term (hypothermia), long-term (organ cultivation) and unlimited (cryopreservation). While there are reports of successful application of cryo-conserved corneas for penetrating keratoplasty, its use for this type of transplantation is limited due to complexity of the method and very high requirements for the quality of donor material. However, being a method of unlimited storage, it still attracts the attention of researchers. Taking into account the ongoing development of innovative keratoplasty technologies and the tendency for predominant use of layered grafts that in some cases do not need viable endothelium, methods of preservation of such material for anterior lamellar and intralamellar keratoplasties become relevant. In this context, cryopreservation without the use of cryoprotective agents is promising because it allows simple and fast accumulation of large amount of material with long storage time. Further research on the development of preservation methods of the corneal endothelial layer at sub-zero temperatures may allow storing the material by cryopreservation that will be suitable for penetrating and posterior keratoplasty.

[Influence of TGF-ß cytokine and a number of other biochemical factors on regenerative process]. / Vliianie tsitokina TGF-ß i drugikh faktorov na protsess regeneratsii.

Scarring is one of the main causes of surgical failure in a number of eye diseases, dacryologic conditions in particular. The process of wound healing, including postoperative wound healing, goes through several stages mediated by various biochemical factors, such as growth factors and pro- and anti-inflammatory cytokines. The balance between the latter directly influences the wound healing. However, current data on the effect of these factors on postoperative outcomes are few and contradictory. Thus, in dacryology as well as in other areas of ophthalmology, the role of cytokines and growth factors in healing of surgical wounds is being intensively researched.

Visualization of Mesenchymal Stromal Cells in 2Dand 3D-Cultures by Scanning Electron Microscopy with Lanthanide Contrasting.

Mesenchymal stromal cells from deciduous teeth in 2D- and 3D-cultures on culture plastic, silicate glass, porous polystyrene, and experimental polylactoglycolide matrices were visualized by scanning electron microscopy with lanthanide contrasting. Supravital staining of cell cultures with a lanthanide-based dye (neodymium chloride) preserved normal cell morphology and allowed assessment of the matrix properties of the carriers. The developed approach can be used for the development of biomaterials for tissue engineering.

[SEM visualization of corneal epithelium through lanthanoid staining based on Ca/Nd isomorphous substitution in Ca-dependent molecular systems]. / Vizualizatsiya struktury epiteliya rogovitsy metodom skaniruyushchei elektronnoi mikroskopii s lantanoidnym kontrastirovaniem na osnove Ca/Nd izomorfnogo zameshcheniya v Sa-zavisimykh molekulyarnykh sistemakh.

Cumulative biomicroscopic evidence is usually sufficient for the diagnosis of recurrent corneal erosion or bullous keratopathy, however, exploration of the disease pathogenesis requires subcellular-level visualization of corneal structure. In the current study, lanthanoid staining and scanning electron microscopy were employed to visualize quite a number of structures responsible for epithelium organization. In particular, the study proves possible the use of Ca/Nd isomorphous substitution at Ca2+ sites of cytoadherence proteins for visualization of corresponding cellular structures. AIM: To assess the value of information provided by scanning electron microscopy of corneal epithelium that involves lanthanoid staining based on the Ca/Nd isomorphous substitution in Ca-dependent molecular systems. MATERIAL AND METHODS: Anterior corneal epithelial scrapes were obtained from patients with recurrent corneal erosion or bullous keratopathy and cadaver eyes with no signs of any ophthalmic disease. Samples were then studied under a scanning electron microscope (Zeiss EVO LS10, BSE, EP - 79 Pa, 20-28 kV, Ln-staining with the BioREE assay kit). RESULTS: In all cases, lanthanoid staining of biopsy material provided high-contrast SEM images with well-recognizable structural and ultrastructural elements associated with Ca2+ sites of cytoadherence proteins. CONCLUSION: Lanthanoid staining of biopsy material and subsequent SEM enabled detailed visualization of structural features of the corneal epithelium in various pathologies. Due to the Ca/Nd isomorphism we were able to evaluate structural position of the majority of protein molecules engaged in Ca-dependant processes and, consequently, in cytoadherence. Basing on the neodymium distribution within the basal membrane, we have described local effects of different substances on the lamina densa in the projection of basal layer cell borders that occur after unidirectional ultrafiltration. The results confirm the failure of the junctional adhesion complex in recurrent corneal erosion.

[Hypothesis of immune privilege of the cornea and pathophysiology of graft rejection]. / Gipoteza immunnoi privilegii rogovitsy i patofiziologiia ottorzheniia keratotransplantata.

Transplantation of donated cornea is a radical and pathogenetically oriented measure of rehabilitation for patients with corneal blindness. Unlike other transplantation surgeries, keratoplasty is usually done without tissue typing and systemic immunosuppression. Even so, in the absence of risk factors, grafts can remain clear in as many as 90% of cases. The phenomenon is explained by immune privilege of the cornea. The hypothesis of immune privilege comprises several interrelated mechanisms that ensure long-lasting transparency of the graft. These include transfer limits of immunogenic stimuli to peripheral lymphoid tissues, deviation of the immune response, and neutralization of immune effector elements within the host-graft interface by immunosuppressive ocular environment. A change in any of the said components leads to loss of the immune-privilege status of the cornea, thus, significantly increasing the risk of graft rejection. We know several stages of the response activation cascade in graft rejection that can be influenced therapeutically, namely, antigen absorption, processing, and presentation as well as T-cell expansion and cellular inflow to the eye. The first two stages take place in the eye itself and are susceptible to instillation drugs and gene therapy. New highly selective medications aimed at specific signals from the immune cells and their pathways may be able to help restore the immune privilege of the cornea and improve the results of optical and reconstructive surgeries in high-risk patients.

[Risk factors, clinical presentations, prevention, and treatment of corneal graft rejection]. / Faktory riska, klinicheskie proiavleniia, metody profilaktiki i lecheniia reaktsii ottorzheniia transplantata rogovitsy.

Corneal transplantation is the most common and successful type of allotransplantation surgery. Post-transplant immune response in keratoplasty is less pronounced than that in other transplantation procedures, which is accounted for by anatomical features of the cornea and, also, its low antigenic potential and active immunosuppression. However, the immune privilege of the cornea can be violated by neovascularization, inflammation, or trauma. Patients who require keratoplasty to restore their sight and whose immune privilege is disturbed, fall into a high-risk group and are likely to demonstrate tissue incompatibility and non-transparent engraftment. Two approaches exist as to how graft rejection can be prevented. One of them involves induction of donor-specific tolerance, the other - non-specific suppression of the recipient's immune response. To avoid tissue incompatibility, measures can be taken to restore the immune privilege of the cornea as well as to induce antigen-specific tolerance, which is considered a promising, thought yet experimental, area of modern transplantology. In clinical practice, one pays most attention to improvement of non-specific immune suppression methods based on interfering in the metabolism of immunocompetent cells. Thus, timely prescriptions and proper immunosuppressive tactics with account to possible risk factors determine the outcome in high-risk patients undergoing corneal transplantation surgery.