[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.

[Differences in the cytocompatibility of bone-plastic materials from xenogeneic hydroxyapatite with stem cells from human exfoliated deciduous teeth and adipose tissue-derived mesenchymal stem cells]. / Razlichiia tsitosovmestimosti kostno-plasticheskikh materialov iz ksenogennogo gidroksiapatita s mul'tipotentnymi mezenkhimal'nymi stromal'nymi kletkami, poluchennymi iz pul'py vypavshikh molochnykh zubov i podkozhnogo lipoaspirata.

AIM: To compare the cytocompatibility of osteoplastic materials used in dentistry with stem cells from human exfoliated deciduous teeth (SHED) and adipose tissue-derived mesenchymal stem cells (AD-MSC). MATERIAL AND METHODS: Materials of the brands 'Bio-Oss', 'Indost', 'Bioplast', 'Viscoll' and 'Trikafor' were selected for study purposes. Cultures of SHED and AD-MSC were used for testing. The cytotoxic effect of the materials was determined using MTT test and vital staining with trypan blue. Cell adhesion was assessed by the vital staining of PKH-26. RESULTS: Water extracts of bone-plastic materials from xenogeneic hydroxyapatite of the brands 'Bio-Oss', 'Indost' and 'Bioplast' exert a cytotoxic effect on SHED and do not cause the death of AD-MSC. Materials based on collagen and ß-tricalcium phosphate possess high cytocompatibility with all cell cultures under study. CONCLUSION: From the point of cytocompatibility all the examined bone-plastic materials may be considered safe for the restoration of bone defects. It should be noted that SHED transplantation on the surface of materials containing xenogeneic hydroxypatite is unacceptable.

In Vitro Modeling of Co-Transplantation of Multipotent Stromal Mesenchymal Cells from Orbital Fat Pad and Lipoaspirate of Human Subcutaneous Adipose Tissue in Organ Culture in Collagen Gel.

The interplay of multipotent stromal cells derived from the orbital fat pads and cells of the lipoaspirate from the subcutaneous adipose tissue was studied using in vitro co-transplantation model in an organ culture in a collagen gel. Microscopy findings and intensity of apoptosis and cell proliferation in cultures of lipoaspirate with and without multipotent stromal cells showed that the cells maintained their viability, proliferation capacity, and cytokine secretion activity. Higher proliferatitive activity of cells in cocultures promotes renewal of fat transplant cells and can help to maintain its stable volume in delayed terms after transplantation.

[Urinary bladder substitution using combined membrane based on secretions of human mesenchymal stem cells and type I collagen].

AIM: Despite the widespread use of intestinal cystoplasty, urinary bladder substitution remains a challenging problem due to the complexity of operations and the potentially high risk of complications. A promising alternative may be bio-engineered collagen-based matrices containing stem cells or their secretions. MATERIAL AND METHODS: To evaluate the effectiveness of this bladder substitution modality, an experiment was conducted on 14 male rabbits. The animals underwent resection of urinary bladder, and the formed defect was substituted with a membrane of type I collagen (series 1, 5 rabbits) or a membrane of the same composition containing a conditioned medium with secretion of mesenchymal stem/stromal cells derived from human adipose tissue (series 2, 5 rabbits). In the comparison group (4 rabbits) resection of the bladder and the closure of the defect was carried out without bladder substitution (series 3). RESULTS: At 1 month after surgery, there was a complete epithelization of the inner surface of the implant, and body tissues replaced the collagen matrix. In series 1, the collagen implant was replaced mainly by connective tissue ingrown with occasional solitary smooth muscle cells. In series 2, the newly formed bladder wall contained numerous smooth muscle cells, growing into the collagen matrix and forming the muscular coat. In series 3, the muscular layer regeneration at the scar site was also noted, but it was less intense, which was confirmed by morphometry. In series 2, more active vascularization of the collagen implant occurred due to neo-angiogenesis, which was more intense than that in series 3, and especially in series 1. Functional studies revealed a reduced bladder functional capacity in series 1 and 3, while in series 2 it was close to normal. During filling cystometry, changes in intra-vesical pressure profile in series 2 were close to normal, while in series 1 and 3 infusion of a small volume of saline resulted in a marked increase in intra-vesical pressure, showing a reduced compliance of the reconstructed bladder. Discussion The study findings show that implants based on type I collagen can be effectively used to substitute a part of the urinary bladder wall, but bio-engineered collagen matrix grafts containing cell regeneration stimulants secreted by stem cells in their culture medium seem to be more promising.