Petr Serafimovich Eremin

INTRODUCTION. Post-traumatic fibrosis is a complex pathophysiological process. One of the causes of the onset and progression of the disease is the dysregulation of fibroblast functional activity. The search for biomaterials capable of modulating this cellular transition toward productive regeneration is one of the priority tasks of rehabilitation medicine and bioengineering. AIM. To evaluate the biocompatibility of cellulose nanocrystals with human fibroblasts in vitro and to study their modulatory effect on TGF-β1-induced fibroblast-to-myofibroblast transformation by assessing the expression of α-smooth muscle actin, type I collagen, and fibronectin. MATERIALS AND METHODS. The morphology of fibroblasts, the number of apoptotic cells, cell cycle phases, and the expression of smooth muscle alpha-actin (α-SMA), collagen (COL1a1) and fibronectin (Fn) were assessed using light and fluorescence microscopy, immunocytochemistry, enzyme-linked immunosorbent assay (ELISA) and flow cytometry. RESULTS. Culturing fibroblasts in media with cellulose nanocrystals (CNC) at concentrations between 5 and 2.5 mg/ml results in cell death. However, reducing the CNC concentration to 1.25 mg/ml or below does not have a cytotoxic effect on human fibroblasts. Furthermore, co-culturing fibroblasts with CNC at a concentration of 0.5 mg/ml does not alter the ratio of live, apoptotic, and dead cells, nor does it affect the distribution of cells across different cell cycle phases. When transforming growth factor beta-1 (TGF-β1) is added to the culture medium, it increases the levels of α-SMA from 67 ± 7 ng/mL to 166 ± 9 ng/mL, COL1a1 from 3.4 ± 0.5 ng/mL to 7 ± 1 ng/mL, and Fn from 156 ± 15 ng/mL to 384 ± 27 ng/mL. It was found that CNCs suppress the functional cellular response of human fibroblasts to TGF-β1 stimulation. DISCUSSION. The presence of polysaccharide nanocrystals in the culture medium inhibits fibroblast differentiation toward the smooth muscle phenotype, as indicated by low levels of α-SMA and extracellular matrix proteins COL1a1 and fibronectin. CONCLUSION. The results presented in this work expand the understanding of the mechanisms and approaches for regulating cell functional activity, including for the prevention of post-traumatic or postoperative fibrotic contractures, and may serve as a basis for the development of new generations of biomaterials for rehabilitation medicine.

One of the promising directions in non-pharmacological wound treatment is tissue engineering, which includes the development of biomimetic materials. The biomaterials most similar to the native extracellular matrix are those consisting of collagen or its denatured forms. Despite the evident advantages of collagen-based biomaterials, their large-scale application in clinical practice is limited due to rapid biodegradation and low mechanical strength. One method for modifying the functional properties of collagen biomaterials is the formation of additional crosslinks between adjacent collagen polypeptide chains, including through the use of carboxylic acid salts.    The aim of this study was to evaluate, in vitro, the biodegradation and functional activity of human fibroblasts to a collagen hydrogel modified with tartrate or citrate salts.    Material and methods.  Denatured type I collagen from “First Alive Collagen” (Russia) and 80 mM solutions of sodium tartrate and sodium citrate were used. Mechanical properties of the samples were assessed using a TX-700 texture analyzer (Lamy Rheology Instruments, France). Using flow cytometry, light microscopy, and luminescence microscopy, the influence of the biomaterials on the number of apoptotic cells, adhesion, viability and functional activity of fibroblasts in vitro was assessed.    Results.  It was established that modification of a collagen hydrogel with tricarboxylic acid salts yields hydrogel biomaterials with improved strength characteristics and resistance to biodegradation in vitro. The obtained modified hydrogel forms exhibited no cytotoxic effect and were capable of supporting the growth and proliferative activity of fibroblasts on their surface. The ability of the hydrogel modified with citrate salt to stimulate fibroblast production of extracellular matrix proteins was revealed.    Conclusions.  The obtained results can be used in the design of biomaterials for stimulating reparative regeneration and preventing fibrotic diseases.

INTRODUCTION. It is known that the secretome of mesenchymal stromal cells exhibits high efficacy in the therapy of various diseases. However, there are limitations hindering its widespread introduction into clinical practice, such as donor variability including donor age, health status, and genetic characteristics. In this regard, the search for new approaches and methods to address this issue is ongoing. A unique natural resource is the antlers of the Altai maral, which represent a natural “bioreactor” of stem cells and growth factors. Despite the increasing interest in this subject, to date there are no studies evaluating the pro-regenerative effect of the secretome from Altai maral antler mesenchymal stromal cells. AIM. To characterize the component composition and biological activity of the stem cell secretome from Altai maral antlers to scientifically substantiate the possibility of its use as a basis for the development of cell-free therapeutic products in regenerative medicine. MATERIALS AND METHODS. The study was conducted at the National Medical Research Center for Rehabilitation and Balneology of the Ministry of Health of Russia, from October to December 2025. Concentration of the secretome from Altai maral antler mesenchymal stromal cells (MSC-MA) and human adipose tissue mesenchymal stromal cells (MSC-AT) was performed by lyophilization. The pro-regenerative effect of the MSC-MA and MSC-AT secretomes was evaluated using a model of acid-induced damage to human fibroblasts. Using light and luminescence microscopy, as well as flow cytometry, the morphology, proliferative activity, and the number of live, apoptotic, and dead cells in the human fibroblast population were assessed. RESULTS. It was established that the concentration of growth factors in the MSC-MA secretome is on average 50 % higher compared to MSC-AT. The ability of MSC-MA to stimulate the viability of fibroblasts with acid-induced damage was revealed, which is expressed in the restoration of their proliferative activity, an increase in the number of live cells in the population from 48 ± 7 % to 85 ± 3 %, and a decrease in the number of apoptotic cells from 24 ± 4 % to 5 ± 1 %. It was shown that the effectiveness of the stimulating effect of the MSC-MA secretome is comparable to the pro-regenerative effect of the human MSC-AT secretome. DISCUSSION. The obtained results complement the literature data and demonstrate that the MSC-MA secretome, which is xenogeneic with respect to human fibroblasts, is capable of exerting a pro-regenerative effect and stimulating the recovery of the fibroblast cell population with acid-induced damage. CONCLUSION. The obtained results confirm the promising potential of using MSC-AS and MSC-AT as a biological resource for the development of cell-free therapeutic products, and also emphasize the need to select an optimal method for obtaining the secretome to maximally preserve its functional activity.

INTRODUCTION. Radiation-induced skin damage remains a serious clinical problem, affecting a significant proportion of patients undergoing radiation therapy, as well as individuals exposed to radiation due to accidents or environmental factors. The pathogenesis of such damage is extremely complex and includes both acute and delayed cellular responses — deoxyribonucleic acid (DNA) damage, oxidative stress, inflammation, vascular abnormalities, as well as activation of apoptosis, necrosis, and cellular senescence in epidermal and dermal structures. AIM. To summarize current understanding of the molecular mechanisms underlying radiation-induced skin damage and evaluate current therapeutic approaches, including regenerative medicine technologies. MATERIALS AND METHODS. A review of the literature was conducted using the PubMed and ScienceDirect databases. Dates of access: September–October 2025. MAIN CONTENT OF THE REVIEW. This review systematizes current data on the molecular and cellular mechanisms of radiation-induced skin damage, including DNA damage, redox homeostasis disruption, inflammatory and vascular responses, apoptosis, necrosis, and senescence. Particular attention is paid to the analysis of new regenerative approaches cellular, acellular, and bioengineered technologies aimed at restoring skin structure and function. The outlooks for the use of mesenchymal stem cells, the cellular component of the stromal-vascular fraction, exosomes, as well as hydrogels and biopolymer coatings are considered. CONCLUSION. The topic is relevant due to a high incidence of skin complications in patients undergoing radiation therapy and a lack of universal treatment standards. A comprehensive understanding of the pathogenetic mechanisms and the development of regenerative technologies offer the potential to create personalized therapeutic protocols aimed at restoring morphofunctional integrity and improving patients’ quality of life.

The growing use of computed tomography (CT) in medicine requires a better understanding of how low-dose radiation affects human stem cells. This study investigated the long-term consequences of CT-level radiation on the secretory profile of human adipose-derived mesenchymal stem cells (AD-MSCs). AD-MSCs were exposed to radiation regimens simulating a single or multiple head CT scans, or to a single 2 Gy therapeutic dose, and their secretion of 41 cytokines, chemokines, and growth factors was monitored during long-term culture. At the early passage, AD-MSCs receiving a single 2 Gy dose showed a coordinated increase in several lymphocyte-regulating cytokines compared to cells exposed to multiple CT scans. However, these initial differences were not sustained. Long-term culturing led to a progressive and widespread decrease in the secretion of 26 cytokines, chemokines, and growth factors across all groups. By the latest passage, all irradiated cells showed a generalized reduction in secretory function compared to non-irradiated controls. These findings demonstrate that while different radiation regimens trigger distinct immediate responses, long-term culture results in a broad decline of the AD-MSCs secretome, which is accentuated by prior radiation exposure. This underscores the importance of assessing long-term consequences to fully evaluate the functional impact of diagnostic radiation on stem cells.

INTRODUCTION. The cellular secretome (CS) is a complex mixture of bioactive molecules secreted by cells during in vitro cultivation and is considered a promising tool in the creation of tissue-engineered constructs to improve the efficiency of hard and soft tissue regeneration. The CS includes cytokines, growth factors, chemokines, enzymes, exosomes, extracellular vesicles, etc. These paracrine factors secreted by cells play a crucial role in modulating various cellular processes, such as inflammation, angiogenesis, and extracellular matrix remodeling. High biological activity and the ability to modulate cellular responses make the CS a promising alternative to both traditional drug therapy and non-drug treatments using stem cell transplantation. AIM. Characteristics of the current state of research into using cellular secretome to stimulate regeneration processes in damaged tissues. MATERIALS AND METHODS. The literature data was reviewed using the PubMed, BioRxiv and ScienceDirect databases. Query dates: June-August 2025, query depth — 2020–2025. MAIN CONTENT OF THE REVIEW. The use of bioengineering and cell technologies for effective stimulation of regeneration processes of damaged tissue is possible only with a comprehensive interdisciplinary approach. To date, most of the components of the CS that regulate the regeneration of soft and hard tissues have been studied. The mechanisms by which the CS exerts its effect, as well as various types and compositions of secretomes used in tissue engineering, are described. The results of laboratory studies and the results of clinical application of the CS are presented, illustrating the practical benefits and effectiveness of non-drug therapy based on the CS. In addition, the review assesses the existing limitations in the practical application of the secretome, such as variability of composition and adverse immune reactions, and discusses strategies for increasing its therapeutic potential. CONCLUSION. Thus, achievements and discoveries in the field of experimental and regenerative medicine shape the directions of future research, including the need to standardize production methods and further study the mechanisms of action of the CS. The integration of cellular metabolites into tissue-engineered constructs will improve the efficiency of restoration of damaged soft tissues and reduce the recovery period for patients.

An open question in radiobiology concerns whether low doses of radiation are harmful or if cells are able to tolerate such exposure with minimal or no disruption. This issue is relevant for evaluating public health risks associated with the increasing number of medical computed tomography (CT) diagnostic procedures. This study evaluated the impact of CT scan-level exposure on human adipose mesenchymal stem cells (hMSCs) by measuring DNA damage responses (γH2AX, 53BP1, pATM foci), proliferation (Ki-67), senescence (β-galactosidase), and multiple gene expressions. Responses to one or five CT exposures were compared to a 2 Gy X-ray dose at intervals from 1 h to 10 passages post-irradiation. It was shown that CT scan briefly increased DNA damage markers but showed no significant long-term effects. A high dose of 2 Gy X-ray exposure caused sustained DNA damage, decreased proliferation, increased senescence, and significant changes in hundreds of genes even after several cell generations. After a single CT exposure, gene expression changes were minimal, while high-dose exposure led to strong activation of DNA repair and stress response pathways. Five CT scans caused a slight activation of LIF and HSPA1B genes, but these effects were minor compared to the high-dose group. All detected effects from CT scans were not observed by ten cell passages, whereas high-dose effects persisted. In conclusion, typical CT scan exposures have only short-term, mild effects on hMSCs, while high-dose radiation causes lasting cellular and genetic changes.

Introduction. The use of naturally occurring hydrocolloids and hydrogels as components of biomimetic materials has a significant advantage because such biopolymers are highly biocompatible. At the same time, the large-scale introduction of natural hydrogels in tissue engineering and practical medicine is hampered by the complexity of the structure standardization and chemical composition of this class of biopolymers, and, consequently, difficulties in predicting the cellular response to hydrogel biomaterials. One way to solve this problem may be the integration of magnetic nanoparticles into the structure of hydrogel biomaterials. Aim. To evaluate the effect of magnetite nanoparticles on the biocompatibility and adhesion of fibroblasts to the surface of alginate hydrogel. Materials and methods. A 2 % aqueous solution of sodium alginate was used to prepare the alginate hydrogel film. Magnetite nanoparticles treated with citric acid were used to modify the biofunctional properties of alginate hydrogel. Biocompatibility of materials was evaluated by light and luminescence microscopy using fluorescent dyes (DAPI, Rhodamine) and a kit for assessing metabolic activity of cell using a tetrazolium dye (MTT assay). Results and discussion. It was found that the introduction of magnetite nanoparticles into the alginate film increases the biocompatibility of the hydrogel material. After 48 hours of incubation, the number of cells increases from 30 ± 5 to 60 ± 7 pcs/200 μm2, and the metabolic activity of fibroblasts is 93 % of the control values. The surface of the hybrid film acquires the ability to maintain the adhesion and viability of fibroblasts, the number of cells on the surface of the hybrid film is more than 10 times greater than the number of cells adhered to the alginate film. Thus, magnetite nanoparticles modified with citric acid can be used to regulate functional cellular responses to plant-derived hydrogel biomaterials. Conclusion. A new method for the biofunctionalization of alginate hydrogel by including magnetite nanoparticles in its composition is proposed. The integration of magnetite nanoparticles with natural hydrogels and the creation of biomaterials with controlled structural and mechanical properties can be a solution to the problem of predictable cellular response to biopolymers heterogeneous in composition and structure.

This study provides a comparative analysis of various components of mesenchymal stem cells (MSC) conditioned media (CM) obtained using serum-containing and serum-free culture methods, revealing significant differences in their composition and potential clinical applicability. Serum-containing CM exhibits significantly higher levels of total protein, non-vesicular RNA, exosomes, and nanoparticles compared to serum-free CM, reflecting the contribution of both the MSC secretome and residual fetal bovine serum components. Ultrafiltration-based fractionation (0.2 µm–50 kDa) allows the isolation of fraction enriched in exosomes and proteins, preserving the functionally significant components of the MSC secretome. This strategy effectively captures small vesicles and mid-sized proteins while excluding larger or smaller biomolecules, enhancing utility for targeted analyses. The presented data underscore the need for context-driven CM selection and provide information for choosing the optimal strategy for obtaining the MSC secretome balancing yield, purity, and regulatory demands in MSC research and therapy.

INTRODUCTION. Development and improvement of methods and materials used in regenerative medicine for non-drug stimulation of tissue repair will solve a number of clinical problems associated with diseases that impede the normal process of reparative regeneration, such as diabetes, cardiovascular diseases and metabolic disorders. Collagen and its derivatives are already used as components of biomaterials for medical purposes. However, low mechanical strength, rapid biodegradation in physiological environments and weak resistance to enzymes limit the scope and effectiveness of their medical and biological applications. AIM. The aim of the study is to evaluate the effect of carboxylic acids on the strength, biodegradability and biocompatibility of collagen xerogel, in vitro. MATERIALS AND METHODS. The mechanical characteristics of the materials were assessed using a TA.XTplus texture analyzer. The biocompatibility of the materials was assessed by light and fluorescence microscopy using fluorescent dyes (DAPI, Rhodamine) and a Calcein AM (CCK-F) cell viability kit. RESULTS AND DISCUSSION. A xerogel based on denatured collagen with high strength characteristics was created. The parameters of heat treatment and concentrations of carboxylic acids were selected to stabilize the mechanical properties of the hydrogel. It was found that the introduction of citric acid into the hydrogel from denatured collagen and subsequent high-temperature treatment allows to increase the mechanical strength of the xerogel from 59 ± 3 to 82 ± 13 kPa. In addition, the introduction of citric acid into the composition of the xerogel increases its resistance to biodegradation by more than three times. The microenvironment created by the xerogel containing citric acid does not have a cytotoxic effect, but it does inhibit proliferation of fibroblasts. CONCLUSION. The results of the in vitro study showed that the obtained material can become a promising platform for use both as an extracellular scaffold and as an independent biomaterial for filling the volume of tissue lost as a result of surgery or injury.