Dissecting the relationship between antimicrobial peptides and mesenchymal stem cells

Combating Antibiotic Resistance: Mechanisms, Multidrug-Resistant Pathogens, and Novel Therapeutic Approaches: An Updated Review

The escalating global health crisis of antibiotic resistance, driven by the rapid emergence of multidrug-resistant (MDR) bacterial pathogens, necessitates urgent and innovative countermeasures. This review comprehensively examines the diverse mechanisms employed by bacteria to evade antibiotic action, including alterations in cell membrane permeability, efflux pump overexpression, biofilm formation, target site modifications, and the enzymatic degradation of antibiotics. Specific focus is given to membrane transport systems such as ATP-binding cassette (ABC) transporters, resistance-nodulation-division (RND) efflux pumps, major facilitator superfamily (MFS) transporters, multidrug and toxic compound extrusion (MATE) systems, small multidrug resistance (SMR) families, and proteobacterial antimicrobial compound efflux (PACE) families. Additionally, the review explores the global burden of MDR pathogens and evaluates emerging therapeutic strategies, including quorum quenching (QQ), probiotics, postbiotics, synbiotics, antimicrobial peptides (AMPs), stem cell applications, immunotherapy, antibacterial photodynamic therapy (aPDT), and bacteriophage. Furthermore, this review discusses novel antimicrobial agents, such as animal-venom-derived compounds and nanobiotics, as promising alternatives to conventional antibiotics. The interplay between clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (Cas) in bacterial adaptive immunity is analyzed, revealing opportunities for targeted genetic interventions. By synthesizing current advancements and emerging strategies, this review underscores the necessity of interdisciplinary collaboration among biomedical scientists, researchers, and the pharmaceutical industry to drive the development of novel antibacterial agents. Ultimately, this comprehensive analysis provides a roadmap for future research, emphasizing the urgent need for sustainable and cooperative approaches to combat antibiotic resistance and safeguard global health.

Asthma and stem cell therapy

The global incidence of asthma, a leading respiratory disorder affecting more than 235 million people, has dramatically increased in recent years. Characterized by chronic airway inflammation and an imbalanced response to airborne irritants, this chronic condition is associated with elevated levels of inflammatory factors and symptoms such as dyspnea, cough, wheezing, and chest tightness. Conventional asthma therapies, such as corticosteroids, long-acting β-agonists, and anti-inflammatory agents, often evoke diverse adverse reactions and fail to reduce symptoms and hospitalization rates over the long term effectively. These limitations have prompted researchers to explore innovative therapeutic strategies, including stem cell-related interventions, offering hope to those afflicted with this incurable disease. In this review, we describe the characteristics of stem cells and critically assess the potential and challenges of stem cell-based therapies to improve disease management and treatment outcomes for asthma and other diseases.

Therapeutic potential of mesenchymal stem cells for fungal infections: mechanisms, applications, and challenges

As a particularly serious condition in immunocompromised patients, fungal infections (FIs) have increasingly become a public health problem worldwide. Mesenchymal stem cells (MSCs), characterized by multilineage differentiation potential and immunomodulatory properties, are considered an emerging strategy for the treatment of FIs. In this study, the therapeutic potential of MSCs for FIs was reviewed, including their roles played by secreting antimicrobial peptides, regulating immune responses, and promoting tissue repair. Meanwhile, the status of research on MSCs in FIs and the controversies were also discussed. However, the application of MSCs still faces numerous challenges, such as the heterogeneity of cell sources, long-term safety, and feasibility of large-scale production. By analyzing the latest study results, this review intends to offer theoretical support for the application of MSCs in FI treatment and further research.

LL-37 regulates odontogenic differentiation of dental pulp stem cells in an inflammatory microenvironment

BACKGROUND

Inflammation often causes irreversible damage to dental pulp tissue. Dental pulp stem cells (DPSCs), which have multidirectional differentiation ability, play critical roles in the repair and regeneration of pulp tissue. However, the presence of proinflammatory factors can affect DPSCs proliferation, differentiation, migration, and other functions. LL-37 is a natural cationic polypeptide that inhibits lipopolysaccharide (LPS) activity, enhances cytokine production, and promotes the migration of stem cells. However, the potential of LL-37 in regenerative endodontics remains unknown. This study aimed to investigate the regulatory role of LL-37 in promoting the migration and odontogenic differentiation of DPSCs within an inflammatory microenvironment. These findings establish an experimental foundation for the regenerative treatment of pulpitis and provide a scientific basis for its clinical application.

MATERIALS AND METHODS

DPSCs were isolated via enzyme digestion combined with the tissue block adhesion method and identified via flow cytometry. The impact of LL-37 on the proliferation of DPSCs was evaluated via a CCK-8 assay. The recruitment of DPSCs was assessed through a transwell assay. The mRNA expression levels of inflammatory and aging-related genes were assessed via reverse transcription‒polymerase chain reaction (RT‒PCR), western blotting, and enzyme‒linked immunosorbent assay (ELISA). The odontogenic differentiation of DPSCs was assessed through alkaline phosphatase (ALP) staining, alizarin red staining, and RT‒PCR analysis.

RESULTS

LL-37 has the potential to enhance the migration of DPSCs. In an inflammatory microenvironment, LL-37 can suppress the expression of genes associated with inflammation and aging, such as TNF-α, IL-1β, IL-6, P21, P38 and P53. Moreover, it promotes odontogenic differentiation in DPSCs by increasing ALP activity, increasing calcium nodule formation, and increasing the expression of dentin-related genes such as DMP1, DSPP and BSP.

CONCLUSION

These findings suggest that the polypeptide LL-37 facilitates the migration of DPSCs and plays a crucial role in resolving inflammation and promoting cell differentiation within an inflammatory microenvironment. Consequently, LL-37 has promising potential as an innovative therapeutic approach for managing inflammatory dental pulp conditions.

Extracellular vesicles derived from bovine adipose-derived mesenchymal stromal cells enhance in vitro embryo production from lesioned ovaries

BACKGROUND AND AIMS

Ovum pick-up (OPU) is an intrinsic step of in vitro fertilization procedures. Nevertheless, it can cause ovarian lesions and compromise female fertility in bovines. Recently, we have shown that intraovarian injection of adipose-derived mesenchymal stromal cells (AD-MSCs) effectively preserves ovarian function in bovines. Given that MSC-derived extracellular vesicles (MSC-EVs) have been shown to recapitulate several therapeutic effects attributed to AD-MSCs and that they present logistic and regulatory advantages compared to AD-MSCs, we tested whether MSC-EVs would also be useful to treat OPU-induced lesions.

METHODS

MSC-EVs were isolated from the secretome of bovine AD-MSCs, using ultrafiltration (UF) and ultracentrifugation methods. The MSC-EVs were characterized according to concentration and mean particle size, morphology, protein concentration and EV markers, miRNA, mRNA, long noncoding RNA profile, total RNA yield and potential for induction of the proliferation and migration of bovine ovarian stromal cells. We then investigated whether intraovarian injection of MSC-EVs obtained by UF would reduce the negative effects of acute OPU-induced ovarian lesions in bovines. To do so, 20 animals were divided into 4 experimental groups (n = 5), submitted to 4 OPU cycles and different experimental treatments including vehicle only (G1), MSC-EVs produced by 7.5 × 106 AD-MSCs (G2), MSC-EVs produced by 2.5 × 106 AD-MSCs (G3) or 3 doses of MSC-EVs produced by 2.5 × 106 AD-MSCs, injected after OPU sessions 1, 2 and 3 (G4).

RESULTS

Characterization of the MSC-EVs revealed that the size of the particles was similar in the different isolation methods; however, the UF method generated a greater MSC-EV yield. MSC-EVs processed by both methods demonstrated a similar ability to promote cell migration and proliferation in ovarian stromal cells. Considering the higher yield and lower complexity of the UF method, UF-MSC-EVs were used in the in vivo experiment. We evaluated three therapeutic regimens for cows subjected to OPU, noting that the group treated with three MSC-EV injections (G4) maintained oocyte production and increased in vitro embryo production, compared to G1, which presented compromised embryo production following the OPU-induced lesions.

CONCLUSIONS

MSC-EVs have beneficial effects both on the migration and proliferation of ovarian stromal cells and on the fertility of bovines with follicular puncture injury in vivo.

Shh Signaling from the Injured Lung Microenvironment Drives BMSCs Differentiation into Alveolar Type II Cells for Acute Lung Injury Treatment in Mice

Alveolar type II (AT2) cells are key effector cells for repairing damaged lungs. Direct differentiation into AT2 cells from bone marrow mesenchymal stem cells (BMSCs) is a promising approach to treating acute lung injury (ALI). The mechanisms of BMSC differentiation into AT2 cells have not been determined. The Sonic Hedgehog (Shh) pathway is involved in regulating multiple differentiation of MSCs. However, the role of the Shh pathway in mediating the differentiation of BMSCs into AT2 cells remains to be explored. The results showed that BMSCs significantly ameliorated lung injury and improved pulmonary function in mice with ALI. These improvements were accompanied by a relatively high proportion of BMSCs differentiate into AT2 cells and an increase in the total number of AT2 cells in the lungs. Lung tissue extracts from mice with ALI (ALITEs) were used to mimic the injured lung microenvironment. The addition of ALITEs significantly improved the differentiation efficiency of BMSCs into AT2 cells along with activation of the Shh pathway. The inhibition of the Shh pathway not only reduced the differentiation rate of BMSCs but also failed to mitigate lung injury and regenerate AT2 cells. The results confirmed that promoting AT2 cell regeneration through the differentiation of BMSCs into AT2 cells is one of the important therapeutic mechanisms for the treatment of ALI with BMSCs. This differentiation process is highly dependent on Shh pathway activation in BMSCs in the injured lung microenvironment.

Advancements in diabetic foot ulcer research: Focus on mesenchymal stem cells and their exosomes

Diabetes represents a widely acknowledged global public health concern. Diabetic foot ulcer (DFU) stands as one of the most severe complications of diabetes, its occurrence imposing a substantial economic burden on patients, profoundly impacting their quality of life. Despite the deepening comprehension regarding the pathophysiology and cellular as well as molecular responses of DFU, the current therapeutic arsenal falls short of efficacy, failing to offer a comprehensive remedy for deep-seated chronic wounds and microvascular occlusions. Conventional treatments merely afford symptomatic alleviation or retard the disease's advancement, devoid of the capacity to effectuate further restitution of compromised vasculature and nerves. An escalating body of research underscores the prominence of mesenchymal stem cells (MSCs) owing to their paracrine attributes and anti-inflammatory prowess, rendering them a focal point in the realm of chronic wound healing. Presently, MSCs have been validated as a highly promising cellular therapeutic approach for DFU, capable of effectuating cellular repair, epithelialization, granulation tissue formation, and neovascularization by means of targeted differentiation, angiogenesis promotion, immunomodulation, and paracrine activities, thereby fostering wound healing. The secretome of MSCs comprises cytokines, growth factors, chemokines, alongside exosomes harboring mRNA, proteins, and microRNAs, possessing immunomodulatory and regenerative properties. The present study provides a systematic exposition on the etiology of DFU and elucidates the intricate molecular mechanisms and diverse functionalities of MSCs in the context of DFU treatment, thereby furnishing pioneering perspectives aimed at harnessing the therapeutic potential of MSCs for DFU management and advancing wound healing processes.

Human β-defensins and their synthetic analogs: Natural defenders and prospective new drugs of oral health

As a family of cationic host defense peptides, human β-defensins (HBDs) are ubiquitous in the oral cavity and are mainly synthesized primarily by epithelial cells, serving as the primary barrier and aiming to prevent microbial invasion, inflammation, and disease while maintaining physiological homeostasis. In recent decades, there has been great interest in their biological functions, structure-activity relationships, mechanisms of action, and therapeutic potential in oral diseases. Meanwhile, researchers are dedicated to improving the properties of HBDs for clinical application. In this review, we first describe the classification, structural characteristics, functions, and mechanisms of HBDs. Next, we cover the role of HBDs and their synthetic analogs in oral diseases, including dental caries and pulp infections, periodontitis, peri-implantitis, fungal/viral infections and oral mucosal diseases, and oral squamous cell carcinoma. Finally, we discuss the limitations and challenges of clinical translation of HBDs and their synthetic analogs, including, but not limited to, stability, bioavailability, antimicrobial activity, resistance, and toxicity. Above all, this review summarizes the biological functions, mechanisms of action, and therapeutic potential of both natural HBDs and their synthetic analogs in oral diseases, as well as the challenges associated with clinical translation, thus providing substantial insights into the laboratory development and clinical application of HBDs in oral diseases.

Nisin-preconditioned mesenchymal stem cells combatting nosocomial Pseudomonas infections

Background

Nosocomial infections caused by multidrug-resistant Pseudomonas aeruginosa are a considerable public health threat, requiring innovative therapeutic approaches.

Objectives

This study explored preconditioning mesenchymal stem cells (MSCs) with the antimicrobial peptide Nisin to enhance their antibacterial properties while maintaining regenerative capacity.

Methods

Human MSCs were preconditioned with varying concentrations of Nisin (0.1-1000 IU/mL) to determine an optimal dose. MSCs preconditioned with Nisin were characterized using microscopy, flow cytometry, gene expression analysis, and functional assays. The effects of preconditioning on the viability, phenotype, differentiation capacity, antimicrobial peptide expression, and antibacterial activity of MSCs against Pseudomonas aeruginosa were tested in vitro. The therapeutic efficacy was evaluated by topically applying conditioned media from Nisin-preconditioned versus control MSCs to infected wounds in a rat model, assessing bacterial burden, healing, host response, and survival.

Results

An optimal Nisin dose of 500 IU/mL was identified, which increased MSC antibacterial gene expression and secretome activity without compromising viability or stemness. Nisin-preconditioned MSCs showed upregulated expression of LL37 and hepcidin. Conditioned media from Nisin-preconditioned MSCs exhibited about 4-fold more inhibition of P. aeruginosa growth compared to non-preconditioned MSCs. In the wound infection model, the secretome of Nisin-preconditioned MSCs suppressed bacterial load, accelerated wound closure, modulated inflammation, and improved survival compared to standard MSC treatments.

Conclusion

This study explores the effect of preconditioning MSCs with the antimicrobial peptide Nisin on enhancing their antibacterial properties while maintaining regenerative capacity. Secreted factors from Nisin-preconditioned MSCs have the potential to attenuate infections and promote healing in vivo. The approach holds translational promise for managing antibiotic-resistant infections and warrants further development. Preconditioned MSCs with Nisin may offer innovative, multifaceted therapies for combating nosocomial pathogens and promoting tissue regeneration.

Comparison of different sources of mesenchymal stem cells: focus on inflammatory bowel disease

Inflammatory bowel disease (IBD) poses a significant challenge in modern medicine, with conventional treatments limited by efficacy and associated side effects, necessitating innovative therapeutic approaches. Mesenchymal stem cells (MSC) have emerged as promising candidates for IBD treatment due to their immunomodulatory properties and regenerative potential. This thesis aims to explore and compare various sources of MSC and evaluate their efficacy in treating IBD. This study comprehensively analyses MSC derived from multiple sources, including bone marrow, adipose tissue, umbilical cord, and other potential reservoirs. Core elements of this investigation include assessing differences in cell acquisition, immunomodulatory effects, and differentiation capabilities among these MSC sources, as well as comparing their clinical trial outcomes in IBD patients to their therapeutic efficacy in animal models. Through meticulous evaluation and comparative analysis, this thesis aims to elucidate disparities in the efficacy of different MSC sources for IBD treatment, thereby identifying the most promising therapeutic applications. The findings of this study are intended to advance our understanding of MSC biology and offer valuable insights for selecting the most effective MSC sources for personalized IBD therapy. Ultimately, this research endeavor will optimise therapeutic strategies for managing inflammatory bowel disease through the utilization of MSC.

Antimicrobial peptide LL37 and regulatory T cell associated with late-onset sepsis in very preterm infants

Stem cell therapy may prevent late-onset sepsis (LOS) via antimicrobial peptide LL37 secretion and regulatory T cell (Treg) regulation. The early prediction of LOS is still a challenge. This study evaluated whether immunological state of LL37 or Tregs precedes LOS. We firstly analyzed the LL37 level, Treg proportion, and LOS incidence in very preterm infants treated with autologous cord blood mononuclear cells (ACBMNCs) in our previous trial. Then, we constructed a prediction model and built validation cohort. We found ACBMNC intervention reduced the incidence of LOS from 27.3% to 6.9% (p = 0.021). LL37 and Treg abundances were higher in the ACBMNCs group. The nomogram demonstrated that early-life Treg and LL37 characteristics were closely associated with LOS (area under the curve, AUC 0.936), with implications for early prediction and timely clinical management. This composite model was also helpful to evaluate the beneficial effect of ACBMNCs intervention on LOS, thus promoting translational research.

Mesenchymal stem cells and their derived exosomes for the treatment of COVID-19

Coronavirus disease 2019 (COVID-19) is an acute respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 infection typically presents with fever and respiratory symptoms, which can progress to severe respiratory distress syndrome and multiple organ failure. In severe cases, these complications may even lead to death. One of the causes of COVID-19 deaths is the cytokine storm caused by an overactive immune response. Therefore, suppressing the overactive immune response may be an effective strategy for treating COVID-19. Mesenchymal stem cells (MSCs) and their derived exosomes (MSCs-Exo) have potent homing abilities, immunomodulatory functions, regenerative repair, and antifibrotic effects, promising an effective tool in treating COVID-19. In this paper, we review the main mechanisms and potential roles of MSCs and MSCs-Exo in treating COVID-19. We also summarize relevant recent clinical trials, including the source of cells, the dosage and the efficacy, and the clinical value and problems in this field, providing more theoretical references for the clinical use of MSCs and MSCs-Exo in the treatment of COVID-19.

Heterologous Production of Antimicrobial Peptides: Notes to Consider

Heavy and irresponsible use of antibiotics in the last century has put selection pressure on the microbes to evolve even faster and develop more resilient strains. In the confrontation with such sometimes called "superbugs", the search for new sources of biochemical antibiotics seems to have reached the limit. In the last two decades, bioactive antimicrobial peptides (AMPs), which are polypeptide chains with less than 100 amino acids, have attracted the attention of many in the control of microbial pathogens, more than the other types of antibiotics. AMPs are groups of components involved in the immune response of many living organisms, and have come to light as new frontiers in fighting with microbes. AMPs are generally produced in minute amounts within organisms; therefore, to address the market, they have to be either produced on a large scale through recombinant DNA technology or to be synthesized via chemical methods. Here, heterologous expression of AMPs within bacterial, fungal, yeast, plants, and insect cells, and points that need to be considered towards their industrialization will be reviewed.

Study of the Effect of Wild-Type and Transiently Expressing CXCR4 and IL-10 Mesenchymal Stromal Cells in a Mouse Model of Peritonitis

Sepsis due to peritonitis is a process associated with an inflammatory state. Mesenchymal stromal cells (MSCs) modulate the immune system due to the paracrine factors released and may be a therapeutic alternative. Three treatment groups were developed in a murine model of peritonitis to verify the effect of human adipose mesenchymal stem cell (hASCs). Additionally, a temporary modification was carried out on them to improve their arrival in inflamed tissues (CXCR4), as well as their anti-inflammatory activity (IL-10). The capacity to reduce systemic inflammation was studied using a local application (peritoneal injection) as a treatment route. Comparisons involving the therapeutic effect of wild-type ASCs and ASCs transiently expressing CXCR4 and IL-10 were carried out with the aim of generating an improved anti-inflammatory response for sepsis in addition to standard antibiotic treatment. However, under the experimental conditions used in these studies, no differences were found between both groups with ASCs. The peritoneal administration of hASCs or genetically modified hASCs constitutes an efficient and safe therapy in our model of mouse peritonitis.

Application of hypoxia-mesenchymal stem cells in treatment of anaerobic bacterial wound infection: wound healing and infection recovery

Mesenchymal stromal cells, commonly referred to as MSCs, are a type of multipotent stem cells that are typically extracted from adipose tissue and bone marrow. In the field of tissue engineering and regenerative medicine, MSCs and their exosomes have emerged as revolutionary tools. Researchers are now devoting greater attention to MSCs because of their ability to generate skin cells like fibroblasts and keratinocytes, as well as their distinctive potential to decrease inflammation and emit pro-angiogenic molecules at the site of wounds. More recent investigations revealed that MSCs can exert numerous direct and indirect antimicrobial effects that are immunologically mediated. Collectively, these antimicrobial properties can remove bacterial infections when the MSCs are delivered in a therapeutic setting. Regardless of the positive therapeutic potential of MSCs for a multitude of conditions, transplanted MSC cell retention continues to be a major challenge. Since MSCs are typically administered into naturally hypoxic tissues, understanding the impact of hypoxia on the functioning of MSCs is crucial. Hypoxia has been postulated to be among the factors determining the differentiation of MSCs, resulting in the production of inflammatory cytokines throughout the process of tissue regeneration and wound repair. This has opened new horizons in developing MSC-based systems as a potent therapeutic tool in oxygen-deprived regions, including anaerobic wound infection sites. This review sheds light on the role of hypoxia-MSCs in the treatment of anaerobic bacterial wound infection in terms of both their regenerative and antimicrobial activities.

Mesenchymal stem cells: A promising antimicrobial therapy in veterinary medicine

Growing antimicrobial resistance (AMR) is a threat to human and animal populations citing the limited available options. Alternative antimicrobial options or functional enhancement of currently available antimicrobials remains only options. One of the potential options seems stem cells especially the mesenchymal stem cells (MSCs) that show antimicrobial properties. These cells additionally have pro-healing effects that may plausibly improve healing outcomes. MSCs antimicrobial actions are mediated either through direct cell-cell contact or their secretome that enhances innate immune mediated antimicrobial activities. These cells synergistically enhance efficacy of currently available antimicrobials especially against the biofilms. Reciprocal action from antimicrobials on the MSCs functionality remains poorly understood. Currently, the main limitation with MSCs based therapy is their limited efficacy. This demands further understanding and can be enhanced through biotechnological interventions. One of the interventional options is the 'priming' to enhance MSCs resistance and specific expression potential. The available literature shows potential antimicrobial actions of MSCs both ex vivo as well as in vivo. The studies on veterinary species are very promising although limited by number and extensiveness in details for their utility as standard therapeutic agents. The current review aims to discuss the role of animals in AMR and the potential antimicrobial actions of MSCs in veterinary medicine. The review also discusses the limitations in their utilization as standard therapeutics.

Revisiting the role of mesenchymal stem cells in tuberculosis and other infectious diseases

Mesenchymal stem cells (MSCs) play diverse roles ranging from regeneration and wound healing to immune signaling. Recent investigations have indicated the crucial role of these multipotent stem cells in regulating various aspects of the immune system. MSCs express unique signaling molecules and secrete various soluble factors that play critical roles in modulating and shaping immune responses, and in some other cases, MSCs can also exert direct antimicrobial effects, thereby helping with the eradication of invading organisms. Recently, it has been demonstrated that MSCs are recruited at the periphery of the granuloma containing Mycobacterium tuberculosis and exert "Janus"-like functions by harboring pathogens and mediating host protective immune responses. This leads to the establishment of a dynamic balance between the host and the pathogen. MSCs function through various immunomodulatory factors such as nitric oxide (NO), IDO, and immunosuppressive cytokines. Recently, our group has shown that M.tb uses MSCs as a niche to evade host protective immune surveillance mechanisms and establish dormancy. MSCs also express a large number of ABC efflux pumps; therefore, dormant M.tb residing in MSCs are exposed to a suboptimal dose of drugs. Therefore, it is highly likely that drug resistance is coupled with dormancy and originates within MSCs. In this review, we discussed various immunomodulatory properties of MSCs, their interactions with important immune cells, and soluble factors. We also discussed the possible roles of MSCs in the outcome of multiple infections and in shaping the immune system, which may provide insight into therapeutic approaches using these cells in different infection models.

Bone Marrow Mesenchymal Stem Cell-Derived Dermcidin-Containing Migrasomes enhance LC3-Associated Phagocytosis of Pulmonary Macrophages and Protect against Post-Stroke Pneumonia

Pneumonia is one of the leading causes of death in patients with acute ischemic stroke (AIS). Antibiotics fail to improve prognosis of patients with post-stroke pneumonia, albeit suppressing infection, due to adverse impacts on the immune system. The current study reports that bone marrow mesenchymal stem cells (BM-MSC) downregulate bacterial load in the lungs of stroke mice models. RNA-sequencing of the lung from BM-MSC-treated stroke models indicates that BM-MSC modulates pulmonary macrophage activities after cerebral ischemia. Mechanistically, BM-MSC promotes the bacterial phagocytosis of pulmonary macrophages through releasing migrasomes, which are migration-dependent extracellular vesicles. With liquid chromatography-tandem mass spectrometry (LC-MS/MS), the result shows that BM-MSC are found to load the antibacterial peptide dermcidin (DCD) in migrasomes upon bacterial stimulation. Besides the antibiotic effect, DCD enhances LC3-associated phagocytosis (LAP) of macrophages, facilitating their bacterial clearance. The data demonstrate that BM-MSC is a promising therapeutic candidate against post-stroke pneumonia, with dual functions of anti-infection and immunol modulation, which is more than a match for antibiotics treatment.

Human Mesenchymal Stem Cell (hMSC) Donor Potency Selection for the "First in Cystic Fibrosis" Phase I Clinical Trial (CEASE-CF)

Human Mesenchymal Stem Cell (hMSC) immunotherapy has been shown to provide both anti-inflammatory and anti-microbial effectiveness in a variety of diseases. The clinical potency of hMSCs is based upon an initial direct hMSC effect on the pro-inflammatory and anti-microbial pathophysiology as well as sustained potency through orchestrating the host immunity to optimize the resolution of infection and tissue damage. Cystic fibrosis (CF) patients suffer from a lung disease characterized by excessive inflammation and chronic infection as well as a variety of other systemic anomalies associated with the consequences of abnormal cystic fibrosis transmembrane conductance regulator (CFTR) function. The application of hMSC immunotherapy to the CF clinical armamentarium is important even in the era of modulators when patients with an established disease still need anti-inflammatory and anti-microbial therapies. Additionally, people with CF mutations not addressed by current modulator resources need anti-inflammation and anti-infection management. Furthermore, hMSCs possess dynamic therapeutic properties, but the potency of their products is highly variable with respect to their anti-inflammatory and anti-microbial effects. Due to the variability of hMSC products, we utilized standardized in vitro and in vivo models to select hMSC donor preparations with the greatest potential for clinical efficacy. The models that were used recapitulate many of the pathophysiologic outcomes associated with CF. We applied this strategy in pursuit of identifying the optimal donor to utilize for the "First in CF" Phase I clinical trial of hMSCs as an immunotherapy and anti-microbial therapy for people with cystic fibrosis. The hMSCs screened in this study demonstrated significant diversity in antimicrobial and anti-inflammatory function using models which mimic some aspects of CF infection and inflammation. However, the variability in activity between in vitro potency and in vivo effectiveness continues to be refined. Future studies require and in-depth pursuit of hMSC molecular signatures that ultimately predict the capacity of hMSCs to function in the clinical setting.

Skin-Derived ABCB5+ Mesenchymal Stem Cells for High-Medical-Need Inflammatory Diseases: From Discovery to Entering Clinical Routine

The ATP-binding cassette superfamily member ABCB5 identifies a subset of skin-resident mesenchymal stem cells (MSCs) that exhibit potent immunomodulatory and wound healing-promoting capacities along with superior homing ability. The ABCB5+ MSCs can be easily accessed from discarded skin samples, expanded, and delivered as a highly homogenous medicinal product with standardized potency. A range of preclinical studies has suggested therapeutic efficacy of ABCB5+ MSCs in a variety of currently uncurable skin and non-skin inflammatory diseases, which has been substantiated thus far by distinct clinical trials in chronic skin wounds or recessive dystrophic epidermolysis bullosa. Therefore, skin-derived ABCB5+ MSCs have the potential to provide a breakthrough at the forefront of MSC-based therapies striving to fulfill current unmet medical needs. The most recent milestones in this regard are the approval of a phase III pivotal trial of ABCB5+ MSCs for treatment of recessive dystrophic and junctional epidermolysis bullosa by the US Food and Drug Administration, and national market access of ABCB5+ MSCs (AMESANAR®) for therapy-refractory chronic venous ulcers under the national hospital exemption pathway in Germany.

Regulatory T-Cell Enhancement, Expression of Adhesion Molecules, and Production of Anti-Inflammatory Factors Are Differentially Modulated by Spheroid-Cultured Mesenchymal Stem Cells

The culture of mesenchymal stem cells (MSCs) as spheroids promotes a more physiological cellular behavior, as it more accurately reflects the biological microenvironment. Nevertheless, mixed results have been found regarding the immunosuppressive properties of spheroid-cultured MSCs (3D-MSCs), the mechanisms of immunoregulation of 3D-MSCs being scarcely described at this point. In the present study, we constructed spheroids from MSCs and compared their immunosuppressive potential with that of MSCs cultured in monolayer (2D-MSCs). First, we evaluated the ability of 2D-MSCs and 3D-MSCs to control the activation and proliferation of T-cells. Next, we evaluated the percentage of regulatory T-cells (Tregs) after the co-culturing of peripheral blood mononuclear cells (PBMCs) with 2D-MSCs and 3D-MSCs. Finally, we investigated the expression of adhesion molecules, as well as the expressions of several anti-inflammatory transcripts in 2D-MSCs and 3D-MSCs maintained in both inflammatory and non-inflammatory conditions. Interestingly, our data show that several anti-inflammatory genes are up-regulated in 3D-MSCs, and that these cells can control T-cell proliferation. Nevertheless, 2D-MSCs are more efficient in suppressing the immune cell proliferation. Importantly, contrary to what was observed in 3D-MSCs, the expressions of ICAM-1 and VCAM-1 are significantly upregulated in 2D-MSCs exposed to an inflammatory environment. Furthermore, only 2D-MSCs are able to promote the enhancement of Tregs. Taken together, our data clearly show that the immunosuppressive potential of MSCs is significantly impacted by their shape, and highlights the important role of cell-cell adhesion molecules for optimal MSC immunomodulatory function.

Mesenchymal Stem Cell-Derived Antimicrobial Peptides as Potential Anti-Neoplastic Agents: New Insight into Anticancer Mechanisms of Stem Cells and Exosomes

Mesenchymal stem cells (MSCs), as adult multipotent cells, possess considerable regenerative and anti-neoplastic effects, from inducing apoptosis in the cancer cells to reducing multidrug resistance that bring them up as an appropriate alternative for cancer treatment. These cells can alter the behavior of cancer cells, the condition of the tumor microenvironment, and the activity of immune cells that result in tumor regression. It has been observed that during inflammatory conditions, a well-known feature of the tumor microenvironment, the MSCs produce and release some molecules called "antimicrobial peptides (AMPs)" with demonstrated anti-neoplastic effects. These peptides have remarkable targeted anticancer effects by attaching to the negatively charged membrane of neoplastic cells, disrupting the membrane, and interfering with intracellular pathways. Therefore, AMPs could be considered as a part of the wide-ranging anti-neoplastic effects of MSCs. This review focuses on the possible anti-neoplastic effects of MSCs-derived AMPs and their mechanisms. It also discusses preconditioning approaches and using exosomes to enhance AMP production and delivery from MSCs to cancer cells. Besides, the clinical administration of MSCs-derived AMPs, along with their challenges in clinical practice, were debated.