Within class II bacteriocins, we assume the presence of a separate subfamily of antimicrobial peptides possessing a broad spectrum of antimicrobial activity. Although these peptides are structurally related to the subclass IIa (pediocin-like) bacteriocins, they have significant differences in biological activities and, probably, a mechanism of their antimicrobial action. A representative of this subfamily is acidocin A from Lactobacillus acidophilus TK9201. We discovered the similarity between acidocin A and acidocin 8912 from Lactobacillus acidophilus TK8912 when analyzing plasmids from lactic acid bacteria and suggested the presence of a single evolutionary predecessor of these peptides. We obtained the C-terminally extended homolog of acidocin 8912, named acidocin 8912A, a possible intermediate form in the evolution of the former. The study of secondary structures and biological activities of these peptides showed their structural similarity to acidocin A; however, the antimicrobial activities of acidocin 8912 and acidocin 8912A were lower than that of acidocin A. In addition, these peptides demonstrated stronger cytotoxic and membranotropic effects. Building upon what we previously discovered about the immunomodulatory properties of acidocin A, we studied its proteolytic stability under conditions simulating those in the digestive tract and also assessed its ability to permeate intestinal epithelium using the Caco-2 cells monolayer model. In addition, we found a pronounced effect of acidocin A against fungi of the genus Candida, which might also expand the therapeutic potential of this bacterial antimicrobial peptide.

Mesenchymal stem cells are a cell population with the ability to self-replicate and differentiate into various types of somatic cells. The present review focuses on the potential of mesenchymal stem cell cultures for cell therapy using transplantable cells or tissue-engineered constructs, and the paracrine factors secreted by mesenchymal stem cells. The methodological aspects of the use of these cells in various diseases both in clinical and preclinical trials have been demonstrated through examples of experimental therapy, with an overview of their primary mechanisms. In the context of cell therapy, mesenchymal stem cells are of significant interest because of their abundance and renewability. Although the differentiation pathways of mesenchymal stem cells are not yet fully elucidated, the cells themselves play a pivotal role in stem cell biology in view of their regulatory properties, including immunomodulatory, antiapoptotic, proliferation-promoting, and antifibrotic effects. It is important to emphasize that the paracrine functions of mesenchymal stem cells are the primary factor contributing to their enhanced integration into tissues, when compared to induced pluripotent stem cells, particularly in the context of cardiac tissue engineering. The review also highlights the role of exogenous factors, such as substrates, in modulating the efficacy of the paracrine effects of mesenchymal stem cells, which is crucial for identifying the optimal cellular microenvironment to enhance therapeutic outcomes without adverse effects.

Introduction: Preservation of isolated hearts in cardioplegic solution at normothermia is a promising strategy for increasing the organ lifespan. Further development of this strategy and search for new products for solution delivery can help optimize the technology of donor heart transportation. Objective: The study was aimed to test the efficacy of device for normothermic constant perfusion flow with innovative lines for the cardioplegic solution delivery (CardioSystemPharma, Khimki, Moscow Region, Russia) according to the Langendorff mode in comparison with a system based on nodes and tubes of Radnoti Langendorff Constant Perfusion Flow Apparatus (ADInstruments, Colorado Springs, USA) in a series of experiments on rat hearts.Methods: The innovative cardioplegic delivery system (CardioSystemPharma) and traditional perfusion system (Radnoti) were compared in experiments on rat hearts at normothermia without cardioplegic solution and using the cardioplegic solution Normacor (Mosfarm, Moscow Region, Russia). The time until complete cardiac arrest and the changes in the NADH coenzyme fluorescence were recorded. After cardiac arrest, immunohistochemical staining of ventricular sections was performed to detect myocardial injury during perfusion.Results: It was shown that the innovative cardioplegic delivery system was not inferior to the traditional perfusion system (Radnoti) and even surpassed it in terms of the time duration for preservation of the isolated heart. It was found that the using of elevated glucose concentration during normothermic perfusion could significantly increase the organ lifespan. The efficacy of normothermic perfusion in the experiment was confirmed by monitoring cellular respiration through recording the NADH fluorescence.Conclusion: Testing showed that long-term preservation under normothermia with usage of an innovative delivery system of Russian manufacture is a promising replacement for Radnoti solution delivery system. Received 16 October 2024. Revised 23 November 2024. Accepted 10 December 2024. FundingThe study was carried out within the framework of the project “Innovative cardioplegic lines for cardiac surgery” under the Agreement on the provision of a grant from the Government of the Moscow Region in the fields of science, technology, engineering and innovation No. 12/04-24 dated 04/27/2024. Conflict of interestThe authors declare no conflict of interest. Contribution of the authorsConception and study design: V.A. Tsvelaya, S.D. Robustova, V.S. Kachan, M.S. Nosov, A.K. Berezhnoy, V.A. Kozlov, K.I. AgladzeData collection and analysis: S.D. Robustova, V.S. Kachan, D.V. Kononova, A.S. Yarovoy, M.A. Gusev, V.V. Litvinenko, V.D. Dzhabrailov, A.A. Brichagina, Z.V. Obrazumova, S.D. Chekalina, S.S. Bakumenko, E.A. Turchaninova, V.A. TsvelayaStatistic analysis: S.D. Robustova, V.S. Kachan, D.V. Kononova, A.S. Yarovoy, M.A. Gusev, V.V. Litvinenko, V.D. Dzhabrailov, A.A. Brichagina, Z.V. Obrazumova, S.D. Chekalina, S.S. Bakumenko, E.A. TurchaninovaDrafting the article: S.D. Robustova, V.S. Kachan, D.V. Kononova, Z.V. Obrazumova, E.A. Turchaninova, V.A. TsvelayaCritical revision of the article: S.D. Robustova, E.A. Turchaninova, V.A. Tsvelaya, K.I. AgladzeFinal approval of the version to be published: S.D. Robustova, V.S. Kachan, D.V. Kononova, A.S. Yarovoy, M.A. Gusev, V.V. Litvinenko, V.D. Dzhabrailov, A.A. Brichagina, Z.V. Obrazumova, S.D. Chekalina, E.A. Turchaninova, S.S. Bakumenko, M.S. Nosov, A.K. Berezhnoy, V.A. Kozlov, V.A. Tsvelaya, K.I. Agladze

A critical obstacle in cardiac cell therapy is the unpredictable and poorly understood initial electrophysiological integration of grafted cardiomyocytes into the host tissue, a process that dictates therapeutic success and arrhythmic risk. Current models fail to capture the earliest stages of functional coupling formation. Here, we employed a tailored bioengineering platform, where single cardiomyocytes were stabilized on minimalist electrospun polycaprolactone (PCL) nanofibers, to model the "graft-host" interface and study the dynamics of excitation wave transmission in real-time. Using high-speed optical mapping enhanced by a custom SUPPORT neural network, we achieved the first quantitative insights into the efficiency of nascent intercellular contacts. We determined that within the first 3 hours, these initial connections are 39-44 times less effective at conducting excitation than mature contacts within the native monolayer, explaining the observed partial (46%) synchronization of grafted cells. This work provides the first direct measurement of the functional deficit during the initial minutes and hours of graft integration. It establishes that simple, inert polymer fibers can act as a catalytic scaffold to enable this fundamental biological process, offering a powerful strategy to deconstruct and ultimately control the integration of engineered tissues (or cells) for safer cell therapies.

A critical obstacle in cardiac cell therapy is the unpredictable and poorly understood initial electrophysiological integration of grafted cardiomyocytes into the host tissue, a process that dictates therapeutic success and arrhythmic risk. Current models fail to capture the earliest stages of functional coupling formation. Here, we employed a tailored bioengineering platform, where single cardiomyocytes were stabilized on minimalist electrospun polycaprolactone (PCL) nanofibers, to model the “graft–host” interface and study the dynamics of excitation wave transmission in real-time. Using high-speed optical mapping enhanced by a custom SUPPORT neural network, we achieved the first quantitative insights into the efficiency of nascent intercellular contacts. We determined that within the first 3 h, these initial connections are 39–44 times less effective at conducting excitation than mature contacts within the native monolayer, explaining the observed partial (46%) synchronization of grafted cells. This work provides the first direct measurement of the functional deficit during the initial minutes and hours of graft integration. It establishes that simple, inert polymer fibers can act as a catalytic scaffold to enable this fundamental biological process, offering a powerful strategy to deconstruct and ultimately control the integration of engineered tissues (or cells) for safer cell therapies.

Background: Heart rhythm disturbances remain a serious problem in modern cardiology. Traditional pacemakers have certain limitations including invasiveness, risk of infection, mechanical complications, and a limited service life. Advances in bioengineering and optogenetics technologies offers new prospects for the production of minimally invasive, biocompatible, and controllable cardiac pacing systems. The combination of cell therapy and optogenetics enables to create a photo-controlled biological pacemaker, free from the key drawbacks of traditional devices. Objective: The aim of this study was to produce photosensitive cellular patches and to further investigate their functionality as an optogenetic tissue-engineered pacemaker in an ex vivo rat heart model. Methods: We engineered a cell-based construct using either human cardiomyocytes derived from induced pluripotent stem cells or neonatal rat cardiomyocytes expressing channelrhodopsin-2. These cells were seeded onto fibrous scaffolds made of poly-L-lactic acid and collagen, coated with fibronectin. The testing model was an isolated, temporarily maintained ex vivo rat heart. Optical mapping of calcium activity was used to record cardiac electrophysiology. Results: Functional coupling between the implanted patch and the host myocardium was observed 35 minutes after implantation. Photostimulation reliably increased the heart rate, which was confirmed by stochastic dominance analysis. The experiments in vitro on cell cultures demonstrated the operational capacity of channelrhodopsin-2 upon illumination with 470 nm light. Conclusion: This study successfully demonstrates a complete technology cycle, from the genetic modification of cells to the control of contractions in a whole organ. It represents a significant step towards developing targeted and safe methods for future temporary cardiac pacing. Our results confirm the fundamental feasibility of a hybrid optogenetic approach and lay the groundwork for further research into creating safe, controllable, and biocompatible next-generation pacemaker systems.