[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.

[Methods of surgical reconstruction of the conjunctiva]. / Metody khirurgicheskoi rekonstruktsii kon"yunktivy.

Reconstruction of the conjunctiva is required for restoration of damaged ocular surface and is an essential part of that process. Traumas, chemical and thermal burns, multiple surgical intervention can seriously damage the integrity of conjunctival tissue and promote the growth of fibrous tissue, scarring of contractures and their shortening, as well as other complications such as trichiasis, erosion and ulcers on the cornea. When a larger area is affected, there may not be enough donor tissue to replace the defect, in which case the tissue grafts are required to be large enough. Modern modifications of surgical techniques and the continued development of tissue engineering, as well as advancements in stem cell research offer promising novel alternatives for solution of those problems. This article reviews the existing surgical methods of conjunctival reconstruction.

[Nerve fiber structure after different types of corneal transplantation]. / Struktura nervnykh volokon posle razlichnykh variantov peresadki rogovitsy.

This review presents basic information about the state of corneal nerve fibers and Langerhans cells before and after keratoplasty. Keratoplasty is a common corneal surgery that carries a risk of graft rejection. The state of corneal nerve fibers can vary after different types of keratoplasty. Corneal confocal microscopy allows in vivo evaluation of the cornea, which can help assess the condition of corneal nerve fibers, as well as reveal the presence of Langerhans cells. Further research in this direction would contribute to identifying the relationship between the state of corneal nerve fibers, the presence of Langerhans cells, and graft rejection.

[Modern prerequisites for creating a collagen-based artificial analogue of the corneal stroma]. / Sovremennye predposylki sozdaniya iskusstvennogo analoga stromy rogovitsy na osnove kollagenovogo materiala.

Despite the fact that various collagen biomaterials have been actively used in ophthalmology for more than 30 years, the problem of creating a material that could replace the donor cornea have not been solved. Recent advances in the field of tissue engineering and regenerative medicine have shifted the focus of approaches to solving the problem of creating an artificial cornea towards laying conditions for the restoration of its specific layers through mechanisms of its own cellular regeneration. In this regard, extracellular matrices based on collagen are gaining popularity. This review discusses general limitations and advantages of collagen for creating an artificial cornea.

[Possibilities of an experimental damaging effect on the retinal pigment epithelium]. / Vozmozhnosti eksperimental'nogo modelirovaniya povrezhdayushchego vozdeistviya na pigmentnyi epitelii setchatki.

PURPOSE: To simulate the damaging effect on retinal pigment epithelium (RPE) in an experiment studying the effect of human neuronal precursors (NPs). MATERIAL AND METHODS: The study was carried out on 31 rabbits (31 eyes) of the Chinchilla breed, which were divided into 3 groups: the 1st group received a subretinal injection of balanced saline solution (BSS); the 2nd group - subretinal injection of BSS with vitrectomy, displacement of the injection bladder away from the injection site using a perfluororganic compound (PFOC) and laser coagulation; the 3rd group - subretinal injection of a culture of NPs using the same method as in the group 2. All rabbits were observed for 21 days using ophthalmoscopy, optical coherence tomography (OCT) and autofluorescence (AF). RESULTS: In the 1st group, 4 out of 5 rabbits were observed to have total retinal detachment and vitreoretinal proliferative processes in the early postoperative period after subretinal injection of the BSS. In the 2nd group, OCT and AF revealed atrophy of the outer and inner layers of the retina as well as disorganization of the photoreceptors-RPE-Bruch's membrane complex in the area of injection on the 21 day after the operation. In the 3rd group, the OCT data obtained during the 21 days of observation showed that a hyperreflective zone at the level of the RPE-Bruch's membrane complex corresponding to the NPs injection site was preserved, while there was a partial loss of the outer retinal layers - but of a smaller volume compared to the BSS injection. The suggested method of subretinal injection led to a reduced number of complications: in the 1st group, postoperative complications amounted to 80%, while in the 2nd and 3rd groups - 45%. CONCLUSION: The study proposes a new method for retinal injection of BSS, which can help reduce RPE degeneration patterns and possible postoperative complications, thus increasing research efficiency. Subretinal injection of a culture of neuronal precursors derived from human induced pluripotent stem cells (iPSCs) in an experiment can serve as a universal model for studying the survival and integration of stem cells.

[Possibilities of treating retinal diseases in patients with damaged retinal pigment epithelium]. / Vozmozhnosti lecheniia zabolevanii setchatki, soprovozhdaiushchikhsia povrezhdeniem retinal'nogo pigmentnogo épiteliia.

Retinal diseases associated with damage to retinal pigment epithelium (PPE) are the most frequent causes of irreversible loss of vision in adults. Since there is no therapeutic treatment available that could repair RPE and its connections with the adjacent photoreceptors, the review focuses on various methods of surgical treatment. One of the most promising methods at present is the use of stem cells derivatives. Results of numerous experimental and clinical trials show that use of human induced pluripotent stem cells in the treatment of degenerative diseases of the retina can be considered effective and promising.

[A comparison of remote and bedside assessment of the NIH Stroke Scale in acute stroke patients]. / Sopostavlenie prikrovatnoi i distantsionnoi otsenok po shkale NIHSS u bol'nykh v ostreishem periode insul'ta.

AIM: Telestroke videoconference for conducting the National Institute of Health Stroke Scale (NIHSS) is recommended when direct bedside evaluation by a stroke specialist is not immediately available for hyperacute stroke assessment. However, some NIHSS-telestroke studies inherit systematic bias due to subjectivity of NIHSS administration. Authors aimed to evaluate NIHSS telestroke assessment, while implementing measures to minimize subjectivity bias. MATERIAL AND METHODS: Ninety acute stroke patients within 48 hours of onset were assessed by 6 stroke neurologists grouped in 15 pairs. Each pair of physicians assessed 6 patients. Patients were allocated through block randomization to a physician pair and order of bedside or remote assessment. Every patient was assessed once at the bedside and once remotely. Remote examination was performed by a neurologist through high-quality videoconferencing, assisted by a nurse at the patient's bedside. Kappa coefficients and the number of patients with a cumulative difference of ≤3 NIHSS points were calculated to compare bedside and remote measures. RESULTS: Cumulative difference of ≤3 NIHSS points was observed in 85.6% (95% CI 76.6%; 92.1%) cases. Therefore, every fifth remote examination may have been inaccurate. Quadratically weighted κ for total NIHSS score was 0.91 (95% CI 0.87; 0.95). Minimal agreements were for commands (κ=0.46), facial palsy (κ=0.43), and ataxia (κ=0.27). Remote assessments were longer than bedside: 8 minutes (IQR 7; 9) versus 6 (IQR 5; 8), p<0.001. CONCLUSION: NIHSS-telestroke assessment using high-quality videoconferencing in the acute stroke settings is closely matched with NIHSS-bedside assessment but it's credibility for clinical use needs further evaluation.