[Closing of nasal septum perforation using adipose stromal vascular fraction: an experimental study]. / Zakrytie perforatsii peregorodki nosa s primeneniem stromal'no-vaskulyarnoi zhirovoi fraktsii: eksperimental'noe issledovanie.

Nasal septal perforation (NSP) is a complex problem in otorhinolaryngology, which leads to impaired nasal breathing and dryness in the nose. This reduces the patient's quality of life and leads to psychological discomfort. The treatment of nasal septum perforation is selected taking into account the clinical manifestations, perforation parameters and general condition of the patient. Currently, a large number of different surgical methods have been described in order to closing the defect of nasal septum. To date, there is no universally accepted method for closing NSP, which stimulates the search and development of new treatment options. OBJECTIVE: Under experimental conditions, to study a new method for closing nasal septum perforation using a collagen scaffold together with adipose stromal vascular fraction containing multipotent mesenchymal stromal cells. MATERIAL AND METHODS: The experiment was carried out on a model of nasal septum perforation in 24 male rabbits divided into four groups, depending on the construct, implanted into the defect zone: the 1st group was the control group - without the introduction of implantation material; the 2nd group - collagen scaffold without adipose stromal vascular fraction; the 3rd group - collagen scaffold with xenogenic adipose stromal vascular fraction; the 4th group - collagen scaffold with allogeneic adipose stromal vascular fraction with further dynamic evaluation of endoscopic control on day 14, after 1 month, 3 months, and 6 months. At month 6, the animals were removed from the experiment, followed by morphological examination in color with hematoxylin and eosin, as well as safranin and methyl green. RESULTS: As a result of the experiment using adipose stromal vascular fraction of allogeneic and xenogenic origin, closing of perforation of the nasal septum of a rabbit for 3 months of dynamic endoscopic control, as well as according to morphological research, was demonstrated. CONCLUSION: Our study showed that the use of adipose stromal vascular fraction containing not only endothelial cells and pericytes, but also multipotent mesenchymal stromal cells in combination with a collagen scaffold closes the perforation of the nasal septum in a rabbit, without increasing the risk of violations of habitual vital activity.

Biodegradable iron-silicon implants produced by additive manufacturing.

Due to many negative and undesirable side effects from the use of permanent implants, the development of temporary implants based on biocompatible and biodegradable materials is a promising area of modern medicine. In the presented study, we have investigated complex-shaped iron-silicon (Fe-Si) scaffolds that can be used as potential biodegradable framework structures for solid implants for bone grafting. Since iron and silicon are biocompatible materials, and their alloy should also have biocompatibility. It has been demonstrated that cells, mesenchymal stromal cells derived from the human umbilical cord (UC-MSC) and 3T3, were attached to, spread, and proliferated on the Fe-Si scaffolds' surface. Most of UC-MSC and 3T3 remained viable, only single dead cells were observed. According to the results of biological testing, the scaffolds have shown that deposition of calcium phosphate particles occurs on day one in the scaffold at the defect site that can be used as a primary marker of osteodifferentiation. These results demonstrate that the 3D-printed porous iron-silicon (Fe-Si) alloy scaffolds are promising structures for bone grafting and regeneration.

Broad-spectrum antibacterial and pro-regenerative effects of photoactivated Photodithazine-Pluronic F127-Chitosan polymer system: In vivo study.

Emerging global danger of multidrug resistant microbes makes it essential to explore new approaches to treat infections. We studied antibacterial and pro-regenerative effects of photodynamic therapy (PDT) performed with water solutions of photodithazine and its complexes with Pluronic F127 and chitosan in rat model of full thickness wound (n = 24) infected by an associated Gram-negative and Gram-positive bacteria culture. Laboratory rats were exposed to PDT 24 and 72 h after the injury. Exudate samples were collected before and after PDT for a microbiological study. Autopsy tissues were excised and fixed in formalin on day 4 of the experiment. Fixed tissues were processed and poured into paraffin. Paraffin sections were stained with hematoxylin and eosin and studied by an experienced pathologist. Microbiological analysis revealed that the photoactivation of photodithazine and its complexes suppressed the associated microflora in vivo and inhibited suppurative inflammation in the wounds. The triple Photodithazine-Pluronic F127-Chitosan system possessed the highest antibacterial activity. The morphological study revealed that PDT with photodithazine polymer complexes accelerated wound healing, promoted restoration of microcirculation, facilitated proliferation of fibroblast and vessels and stimulated collagen synthesis. The Photodithazine-Pluronic F127-Chitosan complex may be successfully applied for PDT to prevent and treat suppurative inflammatory diseases of the skin and soft tissues.

Digging deeper: structural background of PEGylated fibrin gels in cell migration and lumenogenesis.

Fibrin is a well-known tool in tissue engineering, but the structure of its modifications created to improve its properties remains undiscussed despite its importance, e.g. in designing biomaterials that ensure cell migration and lumenogenesis. We sought to uncover the structural aspects of PEGylated fibrin hydrogels shown to contribute to angiogenesis. The analysis of the small-angle X-ray scattering (SAXS) data and ab initio modeling revealed that the PEGylation of fibrinogen led to the formation of oligomeric species, which are larger at a higher PEG : fibrinogen molar ratio. The improvement of optical properties was provided by the decrease in aggregates' sizes and also by retaining the bound water. Compared to the native fibrin, the structure of the 5 : 1 PEGylated fibrin gel consisted of homogenously distributed flexible fibrils with a smaller space between them. Moreover, as arginylglycylaspartic acid (RGD) sites may be partly bound to PEG-NHS or masked because of the oligomerization, the number of adhesion sites may be slightly reduced that may provide the better cell migration and formation of continuous capillary-like structures.

Viscoelastic mapping of cells based on fast force volume and PeakForce Tapping.

Development of fast force volume (FFV), PeakForce Tapping (PFT), and related AFM techniques allow fast acquisition and mapping of a sample's mechanical properties. The methods are well-suited for studying soft biological samples like living cells in a liquid environment. However, the question remains how the measured mechanical properties are related to those acquired with the classical force volume (FV) technique conducted at low indentation rates. The difference is coming mostly from the pronounced viscoelastic behavior of cells, making apparent elastic parameters depending on the probing rate. Here, the viscoelastic analysis was applied directly to the force curves acquired with force volume or PeakForce Tapping by their post-processing based on the Ting's model. Maps from classical force volume, FFV and PFT obtained using special PFT cantilevers and cantilevers modified with microspheres were compared here. With the correct viscoelastic model, which was found to be the power-law rheology model, all the techniques have provided self-consistent results. The techniques were further modified for the mapping of the viscoelastic model-independent complex Young's modulus.

2D/3D buccal epithelial cell self-assembling as a tool for cell phenotype maintenance and fabrication of multilayered epithelial linings in vitro.

Maintaining the epithelial status of cells in vitro and fabrication of a multilayered epithelial lining is one of the key problems in the therapy using cell technologies. When cultured in a monolayer, epithelial cells change their phenotype from epithelial to epithelial-mesenchymal or mesenchymal that makes it difficult to obtain a sufficient number of cells in a 2D culture and to use them in tissue engineering. Here, using buccal epithelial cells from the oral mucosa, we developed a novel approach to recover and maintain the stable cell phenotype and form a multilayered epithelial lining in vitro via the 2D/3D cell self-assembling. Transitioning the cells from the monolayer to non-adhesive 3D culture conditions led to formation of self-assembling spheroids, with restoration of their epithelial characteristics after epithelial-mesenchymal transition. In 7 days, the cells within spheroids restored the apical-basal polarity, and the formation of both tight (ZO1) and adherent (E-cadherin) intercellular junctions was shown. Thus, culturing buccal epithelial cells in a 3D system allowed us to recover and durably maintain the morphological and functional characteristics of epithelial cells. The multilayered epithelial lining formation was achieved after placing spheroids for 7 days onto a hybrid matrix, which consisted of collagen layers and reinforcing poly (lactide-co-glycolide) fibers and was proven promising for replacement of the urothelium. Thus, we offer an effective technique of forming multilayered epithelial linings on carrier-matrices using cell spheroids that was not previously described elsewhere and can find a wide range of applications in tissue engineering, replacement surgery, and regenerative medicine.

Angiogenic potential of spheroids from umbilical cord and adipose-derived multipotent mesenchymal stromal cells within fibrin gel.

One of the essential goals in regenerative medicine is microvascularization which enables an effective blood supply within de novo constructed tissues and organs. In our study, we used two common multipotent mesenchymal stromal cell (MMSC) sources (subcutaneous adipose tissue and Wharton's jelly of the umbilical cord) where is a subpopulation of endothelial precursors. In the medium supplemented with VEGF, the 3D cultures of UC MMSCs and ADSCs promoted the endothelial cell differentiation. To evaluate their ability to form a capillary-like network, we encapsulated spheroids within non-modified and PEGylated fibrin hydrogels. The PEGylated hydrogel supported better the formation of multibranched cords than the pure fibrin gel. Analysis of tubule growth rate, length, and branching showed that the differentiated ADSCs had higher angiogenic potential than the differentiated hUC MMSCs. Our study can be a basis for the development of new strategies in tissue engineering and treatment of vascular diseases.

EVALUATION OF VASCULOGENIC POTENTIAL OF MODIFIED FIBRIN HYDROGEL.

In recent years, engineering of blood vessels, which can provide the effective transport of nutrients and various metabolites, is one of the major challenges in tissue reconstruction. Many researches are carried out to develop cell-seeded bioconstructs based on natural polymers, particularly on PEGylated fibrin. Therefore, the aim of this study was to reveal the optimal component ratio for modified fibrin hydrogels in order to provide favorable conditions for vascular development of endothelial and mesenchymal stem cell co-culture. It has been found out that the PEGylated fibrin hydrogels can support 3D cell growth in HUVECs and hASCs co-culture. The microporous filamentous hydrogel prepared from PEGylated 5 : 1 fibrinogen and using the 1 : 0.2 protein to thrombin ratio had the most favorable microenvironment for cell distribution, growth and development in the studied co-culture that resulted in high levels of expression of proteins required for angiogenesis.