Advances in mesenchymal stem cell research in sepsis

IL-1β-pretreated bone mesenchymal stem cell-derived exosomes alleviate septic endoplasmic reticulum stress via regulating SIRT1/ERK pathway

Background

Endoplasmic reticulum (ER) plays a crucial role in the development of organ injury caused by sepsis. Therefore, it is highly important to devise strategies that specially target ER stress for the treatment of sepsis. Previous research has shown that priming chemokines can enhance the therapeutic effects of mesenchymal stem cells (MSCs). In this study, we aimed to investigate the function and mechanism of exosomes derived from MSCs that were pretreated with IL-1β (IB-exos) in the context of septic ER stress.

Methods

Mouse bone MSCs were preconditioned with or without IL-1β and the supernatant was used for exosome extraction. In vitro sepsis cell mode was induced by treating HUVECs with LPS, while in vivo sepsis model was established through cecal ligation and puncture (CLP) operation in mice. Cell viability, apoptosis, motility, and tube formation were assessed using the EDU proliferation assay, flow cytometry analysis, migration assay, and tube formation assay, respectively. The molecular mechanism was investigated using ELISA, qRT-PCR, Western blot, and immunofluorescence staining.

Results

Pretreatment with IL-1β enhanced the positive impact of MSC-exos on the viability, apoptosis, motility, and tube formation ability of HUVECs. The administration of LPS or CLP increased ER stress response, but this effect was blocked by the treatment of IB-exos. Additionally, IB-exos reversed the inhibitory effects of LPS or CLP on the expression levels of SIRT1 and ERK phosphorylation. Knockdown of SIRT1 counteracted the effects of IB-exos on HUVEC cellular function and ER stress. In a mouse model, the injection of IB-exos mitigated sepsis-induced lung injury by inhibiting ER stress response through the activation of SIRT1.

Conclusion

IB-exos have been found to alleviate sepsis-induced lung injury via inhibiting ER stress through the SIRT1/ERK pathway. These findings indicated that IB-exos could potentially be used as a strategy to mitigate lung injury caused by sepsis.

The Effect of Mesenchymal Stromal Cells on the Mortality of Patients with Sepsis and Septic Shock: A Promising Therapy

Purpose

Sepsis and septic shock are the major causes of death in intensive care units. This study aimed to evaluate the clinical safety and efficacy of mesenchymal stem cells (MSCs) in sepsis and septic shock patients.

Methods

Ten patients were enrolled in the study. Adipose-derived MSC infusions were given (1 × 10⁶/kg, on the 1^st, 3^rd, 5^th, 7^th, and 9^th days of therapy) together with standard therapy. Before the MSC applications, blood samples were collected for cytokine assessment (TNF-α, IFN-γ, IL-2, IL-4, IL-6, IL-10). The clinical and laboratory improvements were recorded and compared with control groups selected retrospectively. The clinical trial was registered on 16.03.2022 with the registration number NCT05283317.

Results

In the study group, the ages of patients ranged from 22 to 68 years, and APACHE II scores ranged from 14 to 42. In the control group, ages ranged from 22 to 80 years and their APACHE II scores were between 14–35. The survival rate in the study group was 100% on the 14^th day whereas it was 70% on the 28^th day. A significant decrease in the SOFA score (adjusted), clinical, and laboratory improvements were observed during the MSC administration. However, no significant cytokine level changes were observed. In the control group, the survival rate of 20 patients was 70% on the 14^th day, whereas 60% was on the 28^th day. While deaths were observed in the control group in the first week of treatment, deaths in the MSCs group were observed between the 15^th and 28^th days.

Conclusion

MSCs treatment may have a positive impact on the survival rates of sepsis during the early phase. However, further randomized controlled studies with a large group of patients are needed. Trial Registration. This trial is registered with ClinicalTrials.gov Identifier: NCT05283317.

The Effect of Mesenchymal Stromal Cells on the Mortality of Patients with Sepsis and Septic Shock: A Promising Therapy

Purpose. Sepsis and septic shock are the major causes of death in intensive care units. This study aimed to evaluate the clinical safety and efficacy of mesenchymal stem cells (MSCs) in sepsis and septic shock patients. Methods. Ten patients were enrolled in the study. Adipose-derived MSC infusions were given (1 × 106/kg, on the 1st, 3rd, 5th, 7th, and 9th days of therapy) together with standard therapy. Before the MSC applications, blood samples were collected for cytokine assessment (TNF-α, IFN-γ, IL-2, IL-4, IL-6, IL-10). The clinical and laboratory improvements were recorded and compared with control groups selected retrospectively. The clinical trial was registered on 16.03.2022 with the registration number NCT05283317. Results. In the study group, the ages of patients ranged from 22 to 68 years, and APACHE II scores ranged from 14 to 42. In the control group, ages ranged from 22 to 80 years and their APACHE II scores were between 14–35. The survival rate in the study group was 100% on the 14th day whereas it was 70% on the 28th day. A significant decrease in the SOFA score (adjusted), clinical, and laboratory improvements were observed during the MSC administration. However, no significant cytokine level changes were observed. In the control group, the survival rate of 20 patients was 70% on the 14th day, whereas 60% was on the 28th day. While deaths were observed in the control group in the first week of treatment, deaths in the MSCs group were observed between the 15th and 28th days. Conclusion. MSCs treatment may have a positive impact on the survival rates of sepsis during the early phase. However, further randomized controlled studies with a large group of patients are needed. Trial Registration. This trial is registered with ClinicalTrials.gov Identifier: NCT05283317.

Human adipose tissue-derived mesenchymal stromal cells and their phagocytic capacity

Mesenchymal stromal cells (MSCs) have evidenced considerable therapeutic potential in numerous clinical fields, especially in tissue regeneration. The immunological characteristics of this cell population include the expression of Toll‐like receptors and mannose receptors, among others. The study objective was to determine whether MSCs have phagocytic capacity against different target particles. We isolated and characterized three human adipose tissue MSC (HAT‐MSC) lines from three patients and analysed their phagocytic capacity by flow cytometry, using fluorescent latex beads, and by transmission electron microscopy, using Escherichia coli, Staphylococcus aureus and Candida albicans as biological materials and latex beads as non‐biological material. The results demonstrate that HAT‐MSCs can phagocyte particles of different nature and size. The percentage of phagocytic cells ranged between 33.8% and 56.2% (mean of 44.37% ± 11.253) according to the cell line, and a high phagocytic index was observed. The high phagocytic capacity observed in MSCs, which have known regenerative potential, may offer an advance in the approach to certain local and systemic infections.

Mesenchymal stem cell and endothelial progenitor cells coinjection improves LPS-induced lung injury via Tie2 activation and downregulation of the TLR4/MyD88 pathway

Sepsis is one of the most important complications of infection with a high mortality rate. Recently, cell therapy has been widely used to reduce the symptoms of sepsis. It has been previously reported that mesenchymal stem cell (MSC) and endothelial progenitor cells (EPC) therapy have beneficial effects in experimental models of sepsis. The effects of coculture of MSC and EPC have not yet been used to treat sepsis. Therefore, the aim of this study was to investigate the therapeutic potential of EPC + MSC coculture on the residual effects of sepsis in a lipopolysaccharide (LPS)-induced mice model. Coinjections of EPC + MSC significantly enhanced the survival rate of LPS-induced mice, decreased concentrations of pro-inflammatory cytokines, and increased the level of anti-inflammatory cytokine. The LPS-induced mice that were treated with EPC + MSC showed a notable reduction in pulmonary edema, hepatic enzymes, and C-reactive protein level compared with the control group. Our results showed that coinjection of EPC + MSC up and downregulates Tie2 and TLR4/MyD88 signaling pathways in LPS-induced mice, respectively. Also, in vitro study showed that viability, adhesion, and migration in coculture cells is significantly decreased after being induced with 10 μg/ml LPS. Our results showed that LPS impaired the functional activity of the cocultured EPC + MSC via upregulation of the TLR4/MyD88 signaling pathway, which may be associated with decreased pTie2/Tie2 expression. In conclusion, coinjection of EPC and MSC modulated the TLR4/MyD88 signaling pathway that leads to reduce the inflammatory response. This study may provide promising results for the introduction of cocultured cells to manage infectious diseases and balance the immune response through immune regulatory function.

Mesenchymal stromal cell-derived syndecan-2 regulates the immune response during sepsis to foster bacterial clearance and resolution of inflammation

Sepsis is a life-threatening process related to a dysregulated host response to an underlying infection, which results in organ dysfunction and poor outcomes. Therapeutic strategies using mesenchymal stromal cells (MSCs) are under investigation for sepsis, with efforts to improve cellular utility. Syndecan (SDC) proteins are transmembrane proteoglycans involved with cellular signaling events including tissue repair and modulating inflammation. Bone marrow-derived human MSCs express syndecan-2 (SDC2) at a level higher than other SDC family members; thus, we explored SDC2 in MSC function. Administration of human MSCs silenced for SDC2 in experimental sepsis resulted in decreased bacterial clearance, and increased tissue injury and mortality compared with wild-type MSCs. These findings were associated with a loss of resolution of inflammation in the peritoneal cavity, and higher levels of proinflammatory mediators in organs. MSCs silenced for SDC2 had a decreased ability to promote phagocytosis of apoptotic neutrophils by macrophages in the peritoneum, and also a diminished capability to convert macrophages from a proinflammatory to a proresolution phenotype via cellular or paracrine actions. Extracellular vesicles are a paracrine effector of MSCs that may contribute to resolution of inflammation, and their production was dramatically reduced in SDC2-silenced human MSCs. Collectively, these data demonstrate the importance of SDC2 for cellular and paracrine function of human MSCs during sepsis.

Host Defense against Klebsiella pneumoniae Pneumonia Is Augmented by Lung-Derived Mesenchymal Stem Cells

Klebsiella pneumoniae is a common cause of Gram-negative pneumonia. The spread of antibiotic-resistant and hypervirulent strains has made treatment more challenging. This study sought to determine the immunomodulatory, antibacterial, and therapeutic potential of purified murine stem cell Ag-1⁺ (Sca-1⁺) lung mesenchymal stem cells (LMSCs) using in vitro cell culture and an in vivo mouse model of pneumonia caused by K pneumoniae. Sca-1⁺ LMSCs are plastic adherent, possess colony-forming capacity, express mesenchymal stem cell markers, differentiate into osteogenic and adipogenic lineages in vitro, and exhibit a high proliferative capacity. Further, these Sca-1⁺ LMSCs are morphologically similar to fibroblasts but differ ultrastructurally. Moreover, Sca-1⁺ LMSCs have the capacity to inhibit LPS-induced secretion of inflammatory cytokines by bone marrow-derived macrophages and neutrophils in vitro. Sca-1⁺ LMSCs inhibit the growth of K pneumoniae more potently than do neutrophils. Sca-1⁺ LMSCs also possess the intrinsic ability to phagocytize and kill K. pneumoniae intracellularly. Whereas the induction of autophagy promotes bacterial replication, inhibition of autophagy enhances the intracellular clearance of K. pneumoniae in Sca-1⁺ LMSCs during the early time of infection. Adoptive transfer of Sca-1⁺ LMSCs in K. pneumoniae-infected mice improved survival, reduced inflammatory cells in bronchoalveolar lavage fluid, reduced inflammatory cytokine levels and pathological lesions in the lung, and enhanced bacterial clearance in the lung and in extrapulmonary organs. To our knowledge, these results together illustrate for the first time the protective role of LMSCs in bacterial pneumonia.

Hydrogels for Large-Scale Expansion of Stem Cells

Stem cells demonstrate considerable promise for various preclinical and clinical applications, including drug screening, disease treatments, and regenerative medicine. Producing high-quality and large amounts of stem cells is in demand for these applications. Despite challenges, as hydrogel-based cell culture technology has developed, tremendous progress has been made in stem cell expansion and directed differentiation. Hydrogels are soft materials with abundant water. Many hydrogel properties, including biodegradability, mechanical strength, and porosity, have been shown to play essential roles in regulating stem cell proliferation and differentiation. The biochemical and physical properties of hydrogels can be specifically tailored to mimic the native microenvironment that various stem cells reside in vivo. A few hydrogel-based systems have been developed for successful stem cell cultures and expansion in vitro. In this review, we summarize various types of hydrogels that have been designed to effectively enhance the proliferation of hematopoietic stem cells (HSCs), mesenchymal stem/stromal cells (MSCs), and pluripotent stem cells (PSCs), respectively. According to each stem cell type's preference, we also discuss strategies for fabricating hydrogels with biochemical and mechanical cues and other characteristics representing microenvironments of stem cells in vivo. STATEMENT OF SIGNIFICANCE: In this review article we summarize current progress on the construction of hydrogel systems for the culture and expansion of various stem cells, including hematopoietic stem cells (HSCs), mesenchymal stem/stromal cells (MSCs), and pluripotent stem cells (PSCs). The Significance includes: (1) Provide detailed discussion on the stem cell niches that should be considered for stem cell in vitro expansion. (2) Summarize various strategies to construct hydrogels that can largely recapture the microenvironment of native stem cells. (3) Suggest a few future directions that can be implemented to improve current in vitro stem cell expansion systems.

Expression of Stromal Cell-Derived Factor-1 by Mesenchymal Stromal Cells Impacts Neutrophil Function During Sepsis

OBJECTIVES

Sepsis results in organ dysfunction caused by a dysregulated host response, in part related to the immune response of a severe infection. Mesenchymal stromal cells are known to modulate the immune response, and expression of stromal cell-derived factor-1 regulates mobilization of neutrophils from the bone marrow. We are investigating the importance of stromal cell-derived factor-1 in mesenchymal stromal cells and its role in promoting neutrophil function after the onset of cecal ligation and puncture-induced sepsis. Stromal cell-derived factor-1 expression was silenced in mesenchymal stromal cells, compared with the control scrambled construct mesenchymal stromal cells.

DESIGN

Animal study and cell culture.

SETTING

Laboratory investigation.

SUBJECTS

BALB/c mice.

INTERVENTIONS

Polymicrobial sepsis was induced by cecal ligation and puncture. shSCR mesenchymal stromal cells and shSDF-1 mesenchymal stromal cells were delivered by tail vein injections to septic mice. The mice were assessed for survival, bacterial clearance, and the inflammatory response during sepsis in each of the groups. Mesenchymal stromal cells were also assessed for their ability to promote bacterial phagocytosis by neutrophils.

MEASUREMENTS AND MAIN RESULTS

Injection of shSCR mesenchymal stromal cells after the onset of sepsis led to an increase in mouse survival (70%) at 7 days, whereas survival of mice receiving shSDF-1 mesenchymal stromal cells was significantly diminished (33%). The loss of survival benefit in mice receiving shSDF-1 mesenchymal stromal cells was associated with less efficient bacterial clearance compared with shSCR mesenchymal stromal cells. Although shSCR mesenchymal stromal cells, or their conditioned medium, were able to increase neutrophil phagocytosis of bacteria, this effect was significantly blunted with shSDF-1 mesenchymal stromal cells. Assessment of peritoneal inflammation revealed that neutrophils were significantly increased and more immature in septic mice receiving shSDF-1 mesenchymal stromal cells. This response was associated with hypocellularity and increased neutrophil death in the bone marrow of mice receiving shSDF-1 mesenchymal stromal cells.

CONCLUSIONS

Expression of stromal cell-derived factor-1 in mesenchymal stromal cells enhances neutrophil function with increased phagocytosis, more efficient clearance of bacteria, and bone marrow protection from depletion of cellular reserves during sepsis.

Exosomes from adipose tissue-derived mesenchymal stem cells ameliorate histone-induced acute lung injury by activating the PI3K/Akt pathway in endothelial cells

BACKGROUND

Mesenchymal stem cells (MSCs), including adipose-derived mesenchymal stem cells (ADSCs), have been shown to attenuate organ damage in acute respiratory distress syndrome (ARDS) and sepsis; however, the underlying mechanisms are not fully understood. In this study, we aimed to explore the potential roles and molecular mechanisms of action of ADSCs in histone-induced endothelial damage.

METHODS

Male C57BL/6 N mice were intravenously injected with ADSCs, followed by histones or a vehicle. The mice in each group were assessed for survival, pulmonary vascular permeability, and histological changes. A co-culture model with primary human umbilical vein endothelial cells (HUVECs) exposed to histones was used to clarify the paracrine effect of ADSCs. Overexpression and inhibition of miR-126 ADSCs were also examined as causative factors for endothelial protection.

RESULTS

The administration of ADSCs markedly improved survival, inhibited histone-mediated lung hemorrhage and edema, and attenuated vascular hyper-permeability in mice. ADSCs were engrafted in the injured lung and attenuated histone-induced endothelial cell apoptosis. ADSCs showed endothelial protection (via a paracrine effect) and Akt phosphorylation in the histone-exposed HUVECs. Notably, increased Akt phosphorylation by ADSCs was mostly mediated by exosomes in histone-induced cytotoxicity and lung damage. Moreover, the expression of miR-126 was increased in exosomes from histone-exposed ADSCs. Remarkably, the inhibition of miR-126 in ADSCs failed to increase Akt phosphorylation in histone-exposed HUVECs.

CONCLUSION

ADSC-derived exosomes may exert protective effects on endothelial cells via activation of the PI3K/Akt pathway.

Do allogeneic bone marrow derived mesenchymal stem cells diminish the inflammatory response to lipopolysaccharide infusion in horses? A pilot study

Endotoxemia is a leading cause of morbidity and mortality in the equine industry, with colic being the most common cause of endotoxemia in horses. The objective of this study was to evaluate the safety and potential efficacy of a single dose of allogeneic equine bone marrow derived mesenchymal stem cells (BM-MSCs) in horses after the IV administration of lipopolysaccharide (LPS). Six horses were administered an IV infusion of 30 ng/kg LPS (O55:B5 Escherichia coli) in 500 ml saline over 30 min. Immediately after infusion test horses (n = 3) were administered 100 × 10⁶ allogeneic BM-MSCs diluted in saline IV and control horses (n = 3) were administered saline. Clinicopathological data, pro-inflammatory cytokine measurements and sCD14 concentrations were compared between groups. No adverse reactions were observed in horses administered BM-MSCs intravenously. There were no significant differences between test and control horses with regard to clinicopathological values or pro-inflammatory cytokine production. At no time point did concentrations of sCD14 exceed the reference range in any horse. Results suggest that administration of a single IV dose of freshly cultured MSCs is safe and well-tolerated in horses with induced endotoxemia. Further study to evaluate their efficacy as a potential therapeutic in a larger number of horses with clinical disease is required.

Antibacterial Fusion Protein BPI21/LL-37 Modification Enhances the Therapeutic Efficacy of hUC-MSCs in Sepsis

Sepsis, which is characterized by multiple organ dysfunctions as a result of an unbalanced host-inflammatory response to pathogens, is potentially a life-threatening condition and a major cause of death in the intensive care units (ICUs). However, effective treatment or intervention to prevent sepsis-associated lethality is still lacking. Human umbilical cord mesenchymal stem cell (hUC-MSC) transplantation has been shown to have potent immunomodulatory properties and improve tissue repair yet lacks direct antibacterial and endotoxin clearance activities. In this study, we engineered hUC-MSCs to express a broad-spectrum antibacterial fusion peptide containing BPI21 and LL-37 (named BPI21/LL-37) and confirmed that the BPI21/LL-37 modification did not affect the stemness and immunoregulatory capacities of hUC-MSCs but remarkably, enhanced its antibacterial and toxin-neutralizing activities in vitro. Furthermore, we showed that administration of BPI21/LL-37-engineered hUC-MSCs significantly reduces serum levels of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and IL-6, whereas increases that of IL-10 in cecal ligation and puncture (CLP)-induced sepsis mouse model. Administration of BPI21/LL-37-engineered hUC-MSCs significantly reduced systemic endotoxin (lipopolysaccharide [LPS]) levels and organ bacterial load, ameliorated damage to multiple organs, and improved survival. Taken together, our study demonstrates that BPI21/LL-37-engineered hUC-MSCs might offer a novel therapeutic strategy to prevent or treat sepsis via enhanced antimicrobial and anti-inflammatory properties to preserve organ functions better.

Medicinal signaling cells: A potential antimicrobial drug store

Medicinal signaling cells (MSCs) are multipotent cells derived from mammalian bone marrow and periosteum that can be extended in culture. They can keep their ability in vitro to form a variety of mesodermal phenotypes and tissues. Over recent years, there has been great attention over MSCs since they can impact the organ transplantation as well as autoimmune and bacterial diseases. MSCs can secrete different bioactive factors such as growth factors, antimicrobial peptides/proteins and cytokines that can suppress the immune system and prevent infection via direct and indirect mechanisms. Moreover, MSCs are able to increase bacterial clearance in sepsis models by producing antimicrobial peptides such as defensins, cathelicidins, lipocalin and hepcidin. It is the aim of the present review to focus on the antibacterial effector functions of MSCs and their mechanisms of action against the pathogenic microbes.

A revealing review of mesenchymal stem cells therapy, clinical perspectives and Modification strategies

Multipotent mesenchymal stem cells (MSCs) have been considerably inspected as effective tool for cell-based therapy of inflammatory, immune-mediated, and degenerative diseases, attributed to their immunomodulatory, immunosuppressive, and regenerative potentials. In the present review, we focus on recent research findings of the clinical applications and therapeutic potential of this cell type, MSCs' mechanisms of therapy, strategies to improve their therapeutic potentials such as manipulations and preconditioning, and potential/unexpected risks which should be considered as a prerequisite step before clinical use. The potential risks would probably include undesirable immune responses, tumor formation and the transmission of incidental agents. Then, we also review some of the milestones in the field, briefly discuss challenges and highlight the new guideline suggested for future directions and perspectives.

Exploring the roles of MSCs in infections: focus on bacterial diseases

Despite human healthcare advances, some microorganisms continuously react evolving new survival strategies, choosing between a commensal fitness and a pathogenic attitude. Many opportunistic microbes are becoming an increasing cause of clinically evident infections while several renowned infectious diseases sustain a considerable number of deaths. Besides the primary and extensively investigated role of immune cells, other cell types are involved in the microbe-host interaction during infection. Interestingly, mesenchymal stem cells (MSCs), the current leading players in cell therapy approaches, have been suggested to contribute to tackling pathogens and modulating the host immune response. In this context, this review critically explores MSCs' role in E. coli, S. aureus, and polymicrobial infections. Summarizing from various studies, in vitro and in vivo results support the mechanistic involvement of MSCs and their derivatives in fighting infection and in contributing to microbial spreading. Our work outlines the double face of MSCs during infection, disease, and sepsis, highlighting potential pitfalls in MSC-based therapy due to the MSCs' susceptibility to pathogens' weapons. We also identify potential targets to improve infection treatments, and propose the potential applications of MSCs for vaccine research.

Mesenchymal stem cells transplantation attenuates brain injury and enhances bacterial clearance in Escherichia coli meningitis in newborn rats

OBJECTIVE

Neonatal meningitis caused by Escherichia coli results in significant mortality and neurological disabilities, with few effective treatments. Recently, we demonstrated that human umbilical cord blood-derived mesenchymal stem cell (hUCB-MSC) transplantation attenuated E. coli-induced severe pneumonia, primarily by reducing inflammation and enhancing bacterial clearance. This study aimed to determine whether intraventricular transplantation of hUCB-MSCs attenuated the brain injury in E. coli meningitis in newborn rats.

METHODS

Meningitis without concomitant bacteremia was induced by intraventricular injection of 5 × 10² colony forming units of K1 (-) E. coli in rats at postnatal day (P)11, and hUCB-MSCs (1 × 10⁵) were transplanted intraventricularly 6 h after induction of meningitis. Antibiotics was started 24 h after modeling.

RESULT

Meningitis modeling induced robust proliferation of E. coli in the cerebrospinal fluid and increased mortality in rat pups, and MSC transplantation significantly reduced this bacterial growth and the mortality rate. Impaired sensorimotor function in the meningitis rats was ameliorated by MSCs injection. MSCs transplantation also attenuated meningitis caused brain injury including cerebral ventricular dilatation, brain cell death, reactive gliosis, and inflammatory response.

CONCLUSION

Intraventricular transplantation of hUCB-MSCs significantly improved survival and attenuated the brain injury via anti-inflammatory and antibacterial effects in experimental neonatal E. coli meningitis.

Gender differences in trauma, shock and sepsis

Despite efforts in prevention and intensive care, trauma and subsequent sepsis are still associated with a high mortality rate. Traumatic injury remains the main cause of death in people younger than 45 years and is thus a source of immense social and economic burden. In recent years, the knowledge concerning gender medicine has continuously increased. A number of studies have reported gender dimorphism in terms of response to trauma, shock and sepsis. However, the advantageous outcome following trauma-hemorrhage in females is not due only to sex. Rather, it is due to the prevailing hormonal milieu of the victim. In this respect, various experimental and clinical studies have demonstrated beneficial effects of estrogen for the central nervous system, the cardiopulmonary system, the liver, the kidneys, the immune system, and for the overall survival of the host. Nonetheless, there remains a gap between the bench and the bedside. This is most likely because clinical studies have not accounted for the estrus cycle. This review attempts to provide an overview of the current level of knowledge and highlights the most important organ systems responding to trauma, shock and sepsis. There continues to be a need for clinical studies on the prevailing hormonal milieu following trauma, shock and sepsis.

A Novel Mechanism of Mesenchymal Stromal Cell-Mediated Protection against Sepsis: Restricting Inflammasome Activation in Macrophages by Increasing Mitophagy and Decreasing Mitochondrial ROS

Sepsis, a systemic inflammatory response to infection, is the leading cause of death in the intensive care unit (ICU). Previous studies indicated that mesenchymal stromal cells (MSCs) might have therapeutic potential against sepsis. The current study was designed to investigate the effects of MSCs on sepsis and the underlying mechanisms focusing on inflammasome activation in macrophages. The results demonstrated that the bone marrow-derived mesenchymal stem cells (BMSCs) significantly increased the survival rate and organ function in cecal ligation and puncture (CLP) mice compared with the control-grouped mice. BMSCs significantly restricted NLRP3 inflammasome activation, suppressed the generation of mitochondrial ROS, and decreased caspase-1 and IL-1β activation when cocultured with bone marrow-derived macrophages (BMDMs), the effects of which could be abolished by Mito-TEMPO. Furthermore, the expression levels of caspase-1, IL-1β, and IL-18 in BMDMs were elevated after treatment with mitophagy inhibitor 3-MA. Thus, BMSCs exert beneficial effects on inhibiting NLRP3 inflammasome activation in macrophages primarily via both enhancing mitophagy and decreasing mitochondrial ROS. These findings suggest that restricting inflammasome activation in macrophages by increasing mitophagy and decreasing mitochondrial ROS might be a crucial mechanism for MSCs to combat sepsis.

Mesenchymal stem cells decrease lung inflammation during sepsis, acting through inhibition of the MAPK pathway

Background

Sepsis is a severe medical condition that ranks among the top 10 causes of death worldwide and which has permanently high incidence rates. Mesenchymal stem cells (MSCs) have been found to be potent modulators of immune responses. More importantly, there is evidence that MSCs have a beneficial effect on preclinical models of polymicrobial sepsis. However, the changes caused by the MSCs in the effector cells of the host immune system remain unclear.

Methods

A mouse model of sepsis (male C57BL/6 mice) with three experimental groups was used for experiments in vivo: a control group, an untreated septic group, and a septic group treated with MSCs. In vitro experiments were performed using a cell line of pulmonary macrophages (RAW 264.7) co-cultured with MSCs and stimulated with lipopolysaccharide (LPS).

Results

In vivo we demonstrated that treatment with MSCs was able to reduce the expression of cyclooxygenase-2 (COX-2) and nuclear factor kappa B (NF-κB), and thereby decrease the production of inflammatory cytokines. In vitro experiments using a co-culture of macrophages with MSCs showed a decrease in COX-2 and NF-κB, and showed that this reduction was directly related to the ability of MSCs to inhibit phosphorylation of ERK, RSK, and p38, enzymes that belong to the family of mitogen-activated protein kinases (MAPKs).

Conclusions

This study demonstrated that MSCs are able to inhibit the MAPK pathway activation, modulating the inflammatory response during sepsis. This understanding that MSCs can remodel the response of host cells and improve the course of sepsis is essential for developing new treatments for this pathology.

Single-stage treatment of infected tibial non-unions and osteomyelitis with bone marrow granulocytes precursors protecting bone graft

PURPOSE

Infected non-unions present a clinical challenge, especially with risk of recurrent infection. Bone marrow contains granulocyte precursors identified in vitro as colony forming units-granulocyte macrophage (CFU-GM) have a prophylactic action against infection. We therefore tested the hypothesis that bone marrow concentrated granulocytes precursors added to a standard bone graft could decrease the risk of recurrence of infection when single-stage treatment of infected tibial non-unions is performed with bone graft.

METHODS

During a single-stage procedure 40 patients with infected tibial non-union received a spongious bone graft supercharged with granulocytes precursors after debridement (study group). A control group (40 patients) was treated in a single stage with local debridement and standard bone graft obtained from the iliac crest. The antibiotic therapy protocol was the same (60 days) in the two groups. CFU-GM progenitors were harvested from bone marrow aspirated on the opposite iliac crest of the site where the cancellous bone was obtained. Union (radiographs and CT scan), a recurrence of clinical infection, and need for subsequent surgery were evaluated.

RESULTS

Thirty-eight (95%) patients who received graft supercharged with granulocytes precursors achieved successful union without recurrence of infection during the seven-year follow-up versus 28 (70%) control patients; for the control group the mean graft resorption volume was 40%, while no bone graft resorption was found for the study group.

CONCLUSION

Supercharging the cancellous bone graft with bone marrow granulocytes precursors protect the site of infected non-union from recurrence of infection and bone resorption of the graft.

Wisp2 disruption represses Cxcr4 expression and inhibits BMSCs homing to injured liver

Liver regeneration/repair is a compensatory regrowth following acute liver failure, and bone marrow-derived mesenchyme stem cell (BMSC) transplantation is an effective therapy that promotes liver regeneration/repair. Wnt1 inducible signaling pathway protein 2 (Wisp2) is highly expressed in BMSCs, however, its function remains unclear. In this work, we used clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein -9 nuclease (CRISPR/Cas9) genome editing technology to knockdown Wisp2 in BMSCs, and these modified cells were then transplanted into rats which were induced by the 2-AAF/PH. By linking the expression of Cas9 to green fluorescent protein (GFP), we tracked BMSCs in the rats. Disruption of Wisp2 inhibited the homing of BMSCs to injured liver and aggravated liver damage as indicated by remarkably high levels of ALT and AST. Moreover, the key factor in BMSC transplantation, C-X-C chemokine receptor type 4 (Cxcr4), was down-regulated in the Wisp2 depleted BMSCs and had a lower expression in the livers of the corresponding rats. By tracing the GFP marker, more BMSCs were observed to differentiate into CD31 positive endothelial cells in the functional Wisp2 cells but less in the Wisp2 gene disrupted cells. In summary, Wisp2 promotes the homing of BMSCs through Cxcr4 related signaling during liver repair in rats.

Activated Mesenchymal Stem Cells Interact with Antibiotics and Host Innate Immune Responses to Control Chronic Bacterial Infections

Chronic bacterial infections associated with biofilm formation are often difficult to resolve without extended courses of antibiotic therapy. Mesenchymal stem cells (MSC) exert antibacterial activity in vitro and in acute bacterial infection models, but their activity in chronic infection with biofilm models has not been previously investigated. Therefore, we studied the effects of MSC administration in mouse and dog models of chronic infections associated with biofilms. Mice with chronic Staphylococcus aureus implant infections were treated by i.v. administration of activated or non-activated MSC, with or without antibiotic therapy. The most effective treatment protocol was identified as activated MSC co-administered with antibiotic therapy. Activated MSC were found to accumulate in the wound margins several days after i.v. administration. Macrophages in infected tissues assumed an M2 phenotype, compared to untreated infections which contained predominately M1 macrophages. Bacterial killing by MSC was found to be mediated in part by secretion of cathelicidin and was significantly increased by antibiotics. Studies in pet dogs with spontaneous chronic multi drug-resistant wound infections demonstrated clearance of bacteria and wound healing following repeated i.v. administration of activated allogeneic canine MSC. Thus, systemic therapy with activated MSC may be an effective new, non-antimicrobial approach to treatment of chronic, drug-resistant infections.

Carbon Monoxide Improves Efficacy of Mesenchymal Stromal Cells During Sepsis by Production of Specialized Proresolving Lipid Mediators

Supplemental Digital Content is available in the text.

Objectives:

Mesenchymal stromal cells are being investigated as a cell-based therapy for a number of disease processes, with promising results in animal models of systemic inflammation and sepsis. Studies are ongoing to determine ways to further improve the therapeutic potential of mesenchymal stromal cells. A gas molecule that improves outcome in experimental sepsis is carbon monoxide. We hypothesized that preconditioning of mesenchymal stromal cells with carbon monoxide ex vivo would promote further therapeutic benefit when cells are administered in vivo after the onset of polymicrobial sepsis in mice.

Design:

Animal study and primary cell culture.

Setting:

Laboratory investigation.

Subjects:

BALB/c mice.

Interventions:

Polymicrobial sepsis was induced by cecal ligation and puncture. Mesenchymal stromal cells, mesenchymal stromal cells-conditioned with carbon monoxide, fibroblasts, or fibroblasts-conditioned with carbon monoxide were delivered by tail vein injections to septic mice. The mice were assessed for survival, bacterial clearance, and the inflammatory response during sepsis in each of the groups. Mesenchymal stromal cells were also assessed for their ability to promote bacterial phagocytosis by neutrophils, the production of specialized proresolving lipid mediators, and their importance for mesenchymal stromal cells function using gene silencing.

Measurements and Main Results:

Ex vivo preconditioning with carbon monoxide allowed mesenchymal stromal cells to be administered later after the onset of sepsis (6 hr), and yet maintain their therapeutic effect with increased survival. Carbon monoxide preconditioned mesenchymal stromal cells were also able to alleviate organ injury, improve bacterial clearance, and promote the resolution of inflammation. Mesenchymal stromal cells exposed to carbon monoxide, with docosahexaenoic acid substrate, produced specialized proresolving lipid mediators, particularly D-series resolvins, which promoted survival. Silencing of lipoxygenase pathways (5-lipoxygenase and 12/15-lipoxygenase), which are important enzymes for specialized proresolving lipid mediator biosynthesis, resulted in a loss of therapeutic benefit bestowed on mesenchymal stromal cells by carbon monoxide.

Conclusions:

Taken together, these data suggest that production of specialized proresolving lipid mediators contribute to improved mesenchymal stromal cell efficacy when exposed to carbon monoxide, resulting in an improved therapeutic response during sepsis.

Optimal Dose and Timing of Umbilical Stem Cells Treatment in Pulmonary Arterial Hypertensive Rats

PURPOSE

Pulmonary arterial hypertension (PAH) is a fatal disease which is characterized by an increase in pulmonary arterial pressure leading to increases in right ventricular afterload. Human umbilical cord blood derived-mesenchymal stem cells (hUCB-MSCs) administered via the jugular vein have been previously shown to improve PAH by reversal treatment. However, the effect of low dosage and transfusion timing of hUCB-MSCs on PAH has not yet been clearly established. Obviously, low dosage treatment can lead to a reduction in costs. This is the first study on early transfusion effect.

MATERIALS AND METHODS

This study was divided into two parts. The first part is an investigation of dose-dependent effect. hUCB-MSCs were administered into 3 groups of rats (UA: 3×10⁶ cells, UB: 1.5×10⁶ cells, UC: 3×10⁵ cells) via the external jugular vein at week 1 after monocrotaline (MCT) injection. The second part is a search for optimal treatment timing in 3×10⁵ cells dose of hUCB-MSCs administered at day 1 for UD group (low dose of hUCB-MSCs at day 1), at day 1 and week 1 for the UE group (dual transfusion of low dose of hUCB-MSCs at day 1 and week 1) and at 1 week for the UF group (reversal treatment of low dose hUCB-MSC at week 1) after MCT injection.

RESULTS

The administration of 3×10⁵ hUCB-MSCs was as effective as the 3×10⁶ dose in decreasing mean right ventricle (RV) pressure and pulmonary pathological changes. Early treatment with hUCB-MSCs improved mean RV pressure, pulmonary pathological changes and heart collagen 3 protein expression levels in PAH.

CONCLUSION

Low-dose early treatment of hUCB-MSCs is as effective as a high dose treatment of hUCB-MSCs in improving PAH although dual or reversal treatment is still more effective.

Long-term Monocyte Dysfunction after Sepsis in Humanized Mice Is Related to Persisted Activation of Macrophage-Colony Stimulation Factor (M-CSF) and Demethylation of PU.1, and It Can Be Reversed by Blocking M-CSF In Vitro or by Transplanting Naïve Autologous Stem Cells In Vivo

The duration of post-sepsis long-term immune suppression is poorly understood. Here, we focused on the role of monocytes (MO) as the pivotal cells for long-term regulation of post-sepsis milieu. Lost ability of MO to adapt is seen in several acute conditions, but it is unclear for how long MO aberrancy post-sepsis can persist. Interestingly, the positive feedback loop sustaining secretion of macrophage-colony stimulation factor (M-CSF) can persist even after resolution of sepsis and significantly alters performance of MO. Here, we investigated the activation of M-CSF, and it as critical regulator of PU.1 in mice surviving 28 days after sepsis. Our primary readout was the ability of MO to differentiate into dendritic cells (DCs; MO→iDC) in vitro since this is one of the critical processes regulating a successful transition from innate to acquired immunity. We utilized a survival modification of the cecal ligation and puncture (CLP) model of sepsis in humanized mice. Animals were sacrificed 28 days after CLP (t_CLP+28d). Untouched (CONTR) or sham-operated (SHAM) animals served as controls. Some animals received rescue from stem cells originally used for grafting 2 weeks after CLP. We found profound decrease of MO→iDC in the humanized mice 28 days after sepsis, demonstrated by depressed expression of CD1a, CD83, and CD209, diminished production of IL-12p70, and depressed ability to stimulate T cells in mice after CLP as compared to SHAM or CONTR. In vitro defect in MO→iDC was accompanied by in vivo decrease of BDCA-3⁺ endogenous circulating DC. Interestingly, post-CLP MO had persistent activation of M-CSF pathway, shown by exaggerated secretion of M-CSF, activation of PU.1, and demethylation of SPII. Neutralization of the M-CSF in vitro reversed the post-CLP MO→iDC aberration. Furthermore, transplantation of naïve, autologous stem cell-derived MO restored CLP-deteriorated ability of MO to become DC, measured as recovery of CD1a expression, enhanced production of IL-12p70, and ability of IL-4 and GM-CSF MO to stimulate allogeneic T cells. Our results suggest the role of epigenetic mediated M-CSF aberration in mediating post-sepsis immune system recovery.

Mesenchymal stem cells in alleviating sepsis-induced mice cardiac dysfunction via inhibition of mTORC1-p70S6K signal pathway

Sepsis-induced cardiac dysfunction remains a major cause of morbidity and mortality in patients suffered from severe trauma. Mesenchymal stem cells (MSCs) -based treatment has been verified as a promising approach to mitigate the sepsis-induced cardiac dysfunction, but the mechanism is still ambiguous. Thus, our study was designed to explore the potential role of MSCs in sepsis-induced cardiac dysfunction. In vivo bioluminescence imaging revealed 80% acute donor cell death of bone marrow-derived MSCs (BM-MSCs) within 3 days after transplantation. However, echocardiography demonstrated that systolic function in wild-type mice group were reduced after sepsis, while the cardiac function was relatively well persevered in cardiac-conditional deletion of Raptor (component of mTORC1 complex) mice group. Raptor KO group treated with BM-MSCs appeared better cardiac function than other groups (P<0.05). In vitro cell study revealed that co-culture of H9C2 (Raptor-Knock down) and BM-MSC could attenuate the level of proinflammatory cytokines and promote the expression of anti-inflammatory cytokine accompanied by mTORC2-Akt activation (P<0.05). In contrast, co-culture H9C2 (Raptor-O.E) and BM-MSC could aggravate the inflammatory response accompanied by the activation of mTORC1-p70S6K and inhibition of mTORC2-Akt (P<0.05). The immunomodulatory property of MSC is related to the inhibition of mTORC1-p70S6K and activation of mTORC2-Akt signaling pathway. mTORC1-p70S6K and mTORC2-Akt pathways were involved in the therapeutic adjuncts of MSC. The possible mechanism due to MSC`s immunomodulatory property through activation of mTORC2-Akt and inhibition of mTORC1-p70S6K signal pathways which may lead to modulate the expression of inflammation cytokines.

Synergistic antibacterial effect of co-administering adipose-derived mesenchymal stromal cells and Ophiophagus hannah L-amino acid oxidase in a mouse model of methicillin-resistant Staphylococcus aureus-infected wounds

Background

Mesenchymal stromal cells (MSCs) and Ophiophagus hannahl-amino acid oxidase (Oh-LAAO) have been reported to exhibit antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA). Published data have indicated that synergistic antibacterial effects could be achieved by co-administration of two or more antimicrobial agents. However, this hypothesis has not been proven in a cell- and protein-based combination. In this study, we investigate if co-administration of adipose-derived MSCs and Oh-LAAO into a mouse model of MRSA-infected wounds would be able to result in a synergistic antibacterial effect.

Methods

MSCs and Oh-LAAO were isolated and characterized by standard methodologies. The effects of the experimental therapies were evaluated in C57/BL6 mice. The animal study groups consisted of full-thickness uninfected and MRSA-infected wound models which received Oh-LAAO, MSCs, or both. Oh-LAAO was administered directly on the wound while MSCs were delivered via intradermal injections. The animals were housed individually with wound measurements taken on days 0, 3, and 7. Histological analyses and bacterial enumeration were performed on wound biopsies to determine the efficacy of each treatment.

Results

Immunophenotyping and differentiation assays conducted on isolated MSCs indicated expression of standard cell surface markers and plasticity which corresponds to published data. Characterization of Oh-LAAO by proteomics, enzymatic, and antibacterial assays confirmed the identity, purity, and functionality of the enzyme prior to use in our subsequent studies. Individual treatments with MSCs and Oh-LAAO in the infected model resulted in reduction of MRSA load by one order of magnitude to the approximate range of 6 log₁₀ colony-forming units (CFU) compared to untreated controls (7.3 log₁₀ CFU). Similar wound healing and improvements in histological parameters were observed between the two groups. Co-administration of MSCs and Oh-LAAO reduced bacterial burden by approximately two orders of magnitude to 5.1 log₁₀ CFU. Wound closure measurements and histology analysis of biopsies obtained from the combinational therapy group indicated significant enhancement in the wound healing process compared to all other groups.

Conclusions

We demonstrated that co-administration of MSCs and Oh-LAAO into a mouse model of MRSA-infected wounds exhibited a synergistic antibacterial effect which significantly reduced the bacterial count and accelerated the wound healing process.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0457-2) contains supplementary material, which is available to authorized users.

Intravenous transplantation of mesenchymal stromal cells has therapeutic effects in a sepsis mouse model through inhibition of septic natural killer cells

Transplantation of mesenchymal stromal cells is a promising strategy for treating sepsis. Natural killer cells are important in the development of sepsis, and their functions can be inhibited by mesenchymal stromal cells, we asked whether mesenchymal stromal cells exert their therapeutic effects through inhibiting the functions of natural killer cells in a septic mouse model generated with cecal ligation puncture method. Using co-cultures of cells, small interfering RNA, enzyme-linked immnuosorbent assays, fluorescence assays, western blotting, and pathological examination, we investigated the levels of inflammatory cytokines, proliferation of natural killer cells, inflammatory infiltration of important organs in mice, and activity of the Janus kinase/signal transducer and activator of transcription signaling pathway and found that mesenchymal stromal cells inhibited the function and proliferation of septic natural killer cells, increased interleukin-10 levels and increased the expression of components, such as Janus kinase 1, Janus kinase 2, and signal transducer and activator of transcription 3 in the Janus kinase/signal transducer and activator of transcription pathway both in vitro and in vivo. We conclude that mesenchymal stromal cells have their therapeutic effect in the septic mouse model through inhibiting the function and proliferation of septic natural killer cells. This biological process may involve interleukin-10 and suppressor of cytokine signaling 3 as well as other pathway components in the Janus kinase/signal transducer and activator of transcription pathway. Transplantation of mesenchymal stromal cells is an effective strategy to treat sepsis.

Could stem cells be the future therapy for sepsis?

The severity and threat of sepsis is well known, and despite several decades of research, the mortality continues to be high. Stem cells have great potential to be used in various clinical disorders. The innate ability of stem cells such as pluripotency, self-renewal makes them potential agents for therapeutic intervention. The pathophysiology of sepsis is a plethora of complex mechanisms which include the initial microbial infection, followed by "cytokine storm," endothelial dysfunction, coagulation cascade, and the late phase of apoptosis and immune paralysis which ultimately results in multiple organ dysfunction. Stem cells could potentially alter each step of this complex pathophysiology of sepsis. Multiple organ dysfunction associated with sepsis most often leads to death and stem cells have shown their ability to prevent the organ damage and improve the organ function. The possible mechanisms of therapeutic potential of stem cells in sepsis have been discussed in detail. The route of administration, dose level, and timing also play vital role in the overall effect of stem cells in sepsis.

Role of kidney injury in sepsis

Kidney injury, including acute kidney injury (AKI) and chronic kidney disease (CKD), has become very common in critically ill patients treated in ICUs. Many epidemiological studies have revealed significant associations of AKI and CKD with poor outcomes of high mortality and medical costs. Although many basic studies have clarified the possible mechanisms of sepsis and septic AKI, translation of the obtained findings to clinical settings has not been successful to date. No specific drug against human sepsis or AKI is currently available. Remarkable progress of dialysis techniques such as continuous renal replacement therapy (CRRT) has enabled control of “uremia” in hemodynamically unstable patients; however, dialysis-requiring septic AKI patients are still showing unacceptably high mortality of 60–80 %. Therefore, further investigations must be conducted to improve the outcome of sepsis and septic AKI. A possible target will be remote organ injury caused by AKI. Recent basic studies have identified interleukin-6 and high mobility group box 1 (HMGB1) as important mediators for acute lung injury induced by AKI. Another target is the disease pathway that is amplified by pre-existing CKD. Vascular endothelial growth factor and HMGB1 elevations in sepsis were demonstrated to be amplified by CKD in CKD-sepsis animal models. Understanding the role of kidney injury as an amplifier in sepsis and multiple organ failure might support the identification of new drug targets for sepsis and septic AKI.

Stem cells for respiratory failure

PURPOSE OF REVIEW

The prognosis of patients with respiratory failure in the ICU remains poor, while current therapeutic approaches are aimed at minimizing ventilator-induced lung injury. Stem cell-based therapies have the potential to transform respiratory failure treatment by achieving lung repair. The purpose of this article is to critically review the large body of clinical and experimental work performed with respect to the use of stem/progenitor cells in respiratory failure, and to discuss current challenges and future directions.

RECENT FINDINGS

Since the initial report of cell therapy for lung injury in 2005, numerous preclinical and clinical studies have been performed that support the ability of various stem cell populations to improve physiologic lung function and reduce inflammation in both infective and sterile acute respiratory distress syndrome. Nevertheless, many important issues (e.g., mechanism of action, long-term engraftment, optimal cell type, dose, route of administration) remain to be resolved.

SUMMARY

Cell-based therapeutics hold promise, particularly for acute respiratory distress syndrome, and early preclinical testing has been encouraging. To advance clinical testing of cell therapies in respiratory failure, and to help ensure that this approach will facilitate bench-to-bedside and bedside-to-bench discoveries, parallel paths of basic and clinical research are needed, including measures of cell therapy effectiveness in vivo and in vitro.

Mesenchymal stem cells as a therapeutic tool to treat sepsis

Sepsis is a clinical syndrome caused by a deregulated host response to an infection. Sepsis is the most frequent cause of death in hospitalized patients. Although knowledge of the pathogenesis of sepsis has increased substantially during the last decades, attempts to design effective and specific therapies targeting components of the derailed host response have failed. Therefore, there is a dramatic need for new and mechanistically alternative therapies to treat this syndrome. Based on their immunomodulatory properties, adult mesenchymal stem or stromal cells (MSCs) can be a novel therapeutic tool to treat sepsis. Indeed, MSCs reduce mortality in experimental models of sepsis by modulating the deregulated inflammatory response against bacteria through the regulation of multiple inflammatory networks, the reprogramming of macrophages and neutrophils towards a more anti-inflammatory phenotype and the release of anti-microbial peptides. This report will review the current knowledge on the effects of MSC treatment in preclinical experimental small animal models of sepsis.

Cell-based therapy for acute organ injury: preclinical evidence and ongoing clinical trials using mesenchymal stem cells

Critically ill patients often suffer from multiple organ failures involving lung, kidney, liver, or brain. Genomic, proteomic, and metabolomic approaches highlight common injury mechanisms leading to acute organ failure. This underlines the need to focus on therapeutic strategies affecting multiple injury pathways. The use of adult stem cells such as mesenchymal stem or stromal cells (MSC) may represent a promising new therapeutic approach as increasing evidence shows that MSC can exert protective effects following injury through the release of promitotic, antiapoptotic, antiinflammatory, and immunomodulatory soluble factors. Furthermore, they can mitigate metabolomic and oxidative stress imbalance. In this work, the authors review the biological capabilities of MSC and the results of clinical trials using MSC as therapy in acute organ injuries. Although preliminary results are encouraging, more studies concerning safety and efficacy of MSC therapy are needed to determine their optimal clinical use. (ANESTHESIOLOGY 2014; 121:1099-121).

Role of p38 MAPK pathway in 17β-estradiol-mediated attenuation of hemorrhagic shock-induced hepatic injury

Although 17β-estradiol (E2) treatment following hemorrhagic shock or ischemic reperfusion prevents organs from dysfunction and injury, the precise mechanism remains unknown. We hypothesize that the E2-mediated attenuation of liver injury following hemorrhagic shock and fluid resuscitation occurs via the p38 mitogen-activated protein kinase (MAPK)-dependent heme oxygenase (HO)-1 pathway. After a 5-cm midline laparotomy, male rats underwent hemorrhagic shock (mean blood pressure ∼40 mmHg for 90 min) followed by fluid resuscitation. At the onset of resuscitation, rats were treated with vehicle, E2 (1 mg/kg) alone, or E2 plus p38 MAPK inhibitor SB-203580 (2 mg/kg), HO-1 inhibitor chromium mesoporphyrin-IX chloride (2.5 mg/kg) or estrogen receptor antagonist ICI 182,780 (3 mg/kg). At 2 h after hemorrhagic shock and fluid resuscitation, the liver injury markers were significantly increased compared with sham-operated control. Hemorrhagic shock resulted in a significant decrease in p38 MAPK phosphorylation compared with the shams. Administration of E2 following hemorrhagic shock normalized liver p38 MAPK phosphorylation, further increased HO-1 expression, and reduced cleaved caspase-3 levels. Coadministration of SB-203580 abolished the E2-mediated attenuation of the shock-induced liver injury markers. In addition, administration of chromium mesoporphyrin-IX chloride or ICI 182,780 abolished E2-mediated increases in liver HO-1 expression or p38 MAPK activation following hemorrhagic shock. Our results collectively suggest that the salutary effects of E2 on hepatic injury following hemorrhagic shock and resuscitation are in part mediated through an estrogen-receptor-related p38 MAPK-dependent HO-1 upregulation.

Therapeutic interventions in sepsis: current and anticipated pharmacological agents

Sepsis is a clinical syndrome characterized by a multisystem response to a pathogenic assault due to underlying infection that involves a combination of interconnected biochemical, cellular and organ-organ interactive networks. After the withdrawal of recombinant human-activated protein C (rAPC), researchers and physicians have continued to search for new therapeutic approaches and targets against sepsis, effective in both hypo- and hyperinflammatory states. Currently, statins are being evaluated as a viable option in clinical trials. Many agents that have shown favourable results in experimental sepsis are not clinically effective or have not been clinically evaluated. Apart from developing new therapeutic molecules, there is great scope for for developing a variety of drug delivery strategies, such as nanoparticulate carriers and phospholipid-based systems. These nanoparticulate carriers neutralize intracorporeal LPS as well as deliver therapeutic agents to targeted tissues and subcellular locations. Here, we review and critically discuss the present status and new experimental and clinical approaches for therapeutic intervention in sepsis.

Bone marrow stromal cells as immunomodulators. A primer for dermatologists

Bone marrow stromal cells (BMSCs, also known as mesenchymal stem cells or MSCs) represent a unique cell population in the bone marrow with a long-known function to support hematopoiesis and replace skeletal tissues. The recent discovery that BMSCs also possess potent immunoregulatory features attracted a great deal of attention from stem cell biologists, immunologists and clinicians of different specialties worldwide. Initial clinical experience along with several animal models suggested that intravenously delivered BMSCs are able to regulate a wide variety of host immune cells and act in a way that is beneficial for the recipient in a variety of diseases. The role of the present review is to give a short introduction to the biology of BMSCs and to summarize our current understanding of how BMSCs modulate the immune system with special emphasis on available clinical data. Considering the audience of this journal we will also attempt to guide dermatologists in choosing the right skin conditions where BMSCs might be considered as a therapeutic alternative.

Mesenchymal stem cells decrease splenocytes apoptosis in a sepsis experimental model

OBJECTIVE AND DESIGN

Mesenchymal stem cells (MSCs) are potent modulators of immune responses. Sepsis is the association of a systemic inflammatory response with an infection. The aim of this study was to test the ability of MSCs derived from adipose tissue, which have immunomodulatory effects, and to inhibit the septic process in an experimental model of mice.

METHODS

Three experimental groups (male C57BL/6 mice) were formed for the test: control group, untreated septic group and septic group treated with MSCs (1 × 10(6) cells/animal).

RESULTS

In the control group, there were no deaths; in the untreated septic group, the mortality rate was 100 % within 26 h; in the septic group treated with MSCs, the mortality rate reached 40 % within 26 h. The group treated with MSCs was able to reduce the markers of tissue damage in the liver and pancreas. The treated group had a reduction of inflammatory markers. Furthermore, the MSCs-treated group was able to inhibit the increase of apoptosis in splenocytes observed in the untreated septic group.

CONCLUSIONS

Our data showed that MSCs ameliorated the immune response with decrease of inflammatory cytokines and increase anti-inflammatory IL-10; moreover, inhibited splenocytes apoptosis and, consequently, inhibited tissue damage during sepsis.

Mesenchymal stromal cells improve survival during sepsis in the absence of heme oxygenase-1: the importance of neutrophils

The use of mesenchymal stromal cells (MSCs) for treatment of bacterial infections, including systemic processes like sepsis, is an evolving field of investigation. This study was designed to investigate the potential use of MSCs, harvested from compact bone, and their interactions with the innate immune system, during polymicrobial sepsis induced by cecal ligation and puncture (CLP). We also wanted to elucidate the role of endogenous heme oxygenase (HO)-1 in MSCs during a systemic bacterial infection. MSCs harvested from the bones of HO-1 deficient (-/-) and wild-type (+/+) mice improved the survival of HO-1(-/-) and HO-1(+/+) recipient mice when administered after the onset of polymicrobial sepsis induced by CLP, compared with the administration of fibroblast control cells. The MSCs, originating from compact bone in mice, enhanced the ability of neutrophils to phagocytize bacteria in vitro and in vivo and to promote bacterial clearance in the peritoneum and blood after CLP. Moreover, after depleting neutrophils in recipient mice, the beneficial effects of MSCs were entirely lost, demonstrating the importance of neutrophils for this MSC response. MSCs also decreased multiple organ injury in susceptible HO-1(-/-) mice, when administered after the onset of sepsis. Taken together, these data demonstrate that the beneficial effects of treatment with MSCs after the onset of polymicrobial sepsis is not dependent on endogenous HO-1 expression, and that neutrophils are crucial for this therapeutic response.

Mesenchymal stem cells in acute lung injury: are they ready for translational medicine?

Acute lung injury (ALI) is a severe clinical condition responsible for high mortality and the development of multiple organ dysfunctions, because of the lack of specific and effective therapies for ALI. Increasing evidence from pre-clinical studies supports preventive and therapeutic effects of mesenchymal stem cells (MSCs, also called mesenchymal stromal cells) in ALI/ARDS (acute respiratory distress syndrome). Therapeutic effects of MSCs were noticed in various delivery approaches (systemic, local, or other locations), multiple origins (bone marrow or other tissues), or different schedules of administrations (before or after the challenges). MSCs could reduce the over-production of inflammatory mediators, leucocyte infiltration, tissue injury and pulmonary failure, and produce a number of benefit factors through interaction with other cells in the process of lung tissue repair. Thus, it is necessary to establish guidelines, standard operating procedures and evaluation criteria for translating MSC-based therapies into clinical application for patients with ALI.

Autologous bone marrow-derived mesenchymal stem cell transplantation promotes liver regeneration after portal vein embolization in cirrhotic rats. J Surg Res. 2013;184:1161-1173. [PMID: 23809154 DOI: 10.1016/j.jss.2013.04.054]

BACKGROUND

Preexisting cirrhosis usually leads to an inadequate and delayed regeneration of the future liver remnant (FLR) after portal vein embolization (PVE). Bone marrow-derived mesenchymal stem cells (BMSC) are promising candidates for therapeutic applications in liver diseases. In this study, the efficacy of autologous BMSCs transplantation to promote FLR regeneration was investigated in a rat cirrhotic model.

METHODS

Autologous BMSCs were expanded and labeled with PKH26, and then were injected immediately into nonembolized lobes after PVE through portal vein in cirrhotic rat. At 7, 14, and 28 d after this, liver weight and Ki-67 labeling index were measured, and blood analysis was performed. Cirrhotic degree of FLR was assessed by hydroxyproline content assay and histopathology. Gene expressions of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), interleukin-10 (IL-10), and matrix metalloproteinase-9 (MMP-9) were detected with real-time reverse transcriptase-polymerase chain reaction. Distribution and hepatocyte differentiation of BMSCs in FLR were determined by confocal microscopy.

RESULTS

Autologous BMSCs significantly increased the FLR weight ratio to the total liver and the Ki-67 labeling index, and serum albumin levels were significantly higher and total bilirubin levels were significantly lower in the BMSCs group compared with the controls without BMSCs transplantation 14 and 28 d post-PVE. BMSCs significantly decreased the hydroxyproline content and collagen accumulation, up-regulated the expressions of HGF, IL-10, VEGF, and MMP-9 28 d post-PVE, and expressed hepatocyte-specific markers, such as α-fetoprotein, cytokeratin 18, and albumin in a time-dependent manner in FLR.

CONCLUSIONS

Autologous BMSCs can differentiate into hepatocyte and promote FLR regeneration after PVE in cirrhotic liver, which may be through improving local microenvironment by decreasing cirrhosis, up-regulating the gene expressions of VEGF, HGF, IL-10, and MMP-9.