Benjamin D. Brewster

Advances in mesenchymal stem cell research in sepsis.

BACKGROUND Sepsis remains a source of morbidity and mortality in the postoperative patient despite appropriate resuscitative and antimicrobial approaches. Recent research has focused upon additional interventions such as exogenous cell-based therapy. Mesenchymal stem cells (MSCs) exhibit multiple beneficial properties through their capacity for homing, attenuating the inflammatory response, modulating immune cells, and promoting tissue healing. Recent animal trials have provided evidence that MSCs may be useful therapeutic adjuncts. MATERIALS AND METHODS A directed search of recent medical literature was performed utilizing PubMed to examine the pathophysiology of sepsis, mechanisms of mesenchymal stem cell interaction with host cells, sepsis animal models, and recent trials utilizing stem cells in sepsis. RESULTS MSCs continue to show promise in the treatment of sepsis by their intrinsic ability to home to injured tissue, secrete paracrine signals to limit systemic and local inflammation, decrease apoptosis in threatened tissues, stimulate neoangiogenesis, activate resident stem cells, beneficially modulate immune cells, and exhibit direct antimicrobial activity. These effects are associated with reduced organ dysfunction and improved survival in animal models. CONCLUSION Research utilizing animal models of sepsis has provided a greater understanding of the beneficial properties of MSCs. Their capacity to home to sites of injury and use paracrine mechanisms to change the local environment to ultimately improve organ function and survival make MSCs attractive in the treatment of sepsis. Future studies are needed to further evaluate the complex interactions between MSCs and host tissues.

Prospective determination of percutaneous endoscopic gastrostomy complication rates in children: Still a safe procedure

BACKGROUND Percutaneous endoscopic gastrostomy (PEG) placement in children has come under scrutiny with reports of improved safety profiles using laparoscopic-assisted techniques. However, these reports are generally limited by their retrospective nature and the inclusion of historically determined PEG complication rates in children. Complication rates associated with PEG placement in children have not been prospectively studied, and a true modern understanding of the safety profile of PEG when performed in children is unknown. We prospectively followed children undergoing PEG to establish a clear and current understanding of the complication rates associated with this procedure. METHODS Consecutive PEG procedures performed between December 2009 and August 2010 at a single, tertiary-care pediatric hospital were enrolled for study. Patients were followed prospectively for 90 days with data regarding complications acquired via standardized interviews at 7, 30, and 90 days postoperatively. RESULTS We enrolled 103 patients for study. Median age and weight at time of operation was 8 months (range, 2 weeks-21 years) and 6.9 kg (range, 2-42). Patients underwent primary placement of either a PEG button (n = 70) or PEG tube (n = 33). There were no intraoperative complications, with a 100% procedure completion rate. Six deaths occurred during this follow-up time period (mean of 37 days postoperatively) and were attributed to causes other than PEG placement. Four patients were lost to follow-up. One PEG tube was electively discontinued before the end of the follow-up period without complication. Of the remaining 92 patients with complete data, 13 complications were observed in 10 patients. Total complication rate was 14%. CONCLUSION Rates of PEG complications observed in this prospective study are low and are generally minor. Observed rates of PEG-specific complications are lower than historic reports. The safety profile of PEG when performed in todays pediatric population remains comparable in safety to techniques such as laparoscopic-assisted gastrostomy.

Interleukin-10 protects the ischemic heart from reperfusion injury via the STAT3 pathway

BACKGROUND Cardiac surgery induces the release of inflammatory mediators that can prolong cardiac dysfunction after operative intervention. Interleukin-10 (IL-10), a potent inhibitor of myocardial inflammation, is a known factor in myocardial protection after ischemia/reperfusion (I/R) injury. We hypothesized that IL-10 activity during initial reperfusion is mediated through the signal transducer and activator of transcription 3 (STAT3) pathway. METHODS Adult rat hearts were isolated and perfused via Langendorff protocol and subjected to global I/R. After determining the effective IL-10 dose, hearts were administered vehicle, IL-10, or IL-10 + Stattic (specific STAT3 inhibitor) 1 min prior to ischemia. After reperfusion, hearts were sectioned and assessed for levels of myocardial inflammatory cytokines and protein. RESULTS The IL-10 minimum effective dose was 1 μg. IL-10-treated hearts had improved markedly myocardial function after global I/R compared to both vehicle and IL-10 + Stattic groups. In addition, IL-10 treatment was associated with a significant decrease in myocardial interleukin-1β (IL-1β) and interleukin-6 (IL-6) and increase in myocardial IL-10. Myocardial STAT3 was elevated markedly in IL-10 treated hearts. CONCLUSION IL-10 improves myocardial function after acute global I/R and suppresses inflammation through the STAT3 pathway. The administration of anti-inflammatory agents may have potential therapeutic applications in cardiac surgery.

Intracoronary Mesenchymal Stem Cells Promote Postischemic Myocardial Functional Recovery, Decrease Inflammation, and Reduce Apoptosis via a Signal Transducer and Activator of Transcription 3 Mechanism

BACKGROUND Signal transducer and activator of transcription 3 (STAT3) regulates myocardial apoptosis, cellular proliferation, and the immune response after ischemia/reperfusion (I/R). STAT3 is also necessary for the production of vascular endothelial growth factor (VEGF) by mesenchymal stem cells (MSCs), which are known to reduce myocardial injury after I/R. However, it remains unknown whether STAT3 is an important mediator of MSC-based cardioprotection. We hypothesized that knockout of stem cell STAT3 would reduce MSC-derived myocardial functional recovery and increase myocardial inflammatory and apoptotic signaling. STUDY DESIGN With a Langendorff apparatus, male rat hearts were subjected to 15 minutes of equilibration and 25 minutes of ischemia, followed by 40 minutes of reperfusion. Immediately before ischemia, hearts received intracoronary infusions of vehicle, wild-type MSCs (WT MSCs) or STAT3 knockout MSCs (STAT3KO MSCs). Heart function was measured continuously. Myocardial homogenates were analyzed for production of interleukin (IL)-1, IL-6, and tumor necrosis factor-α (TNF-α). Additionally, MSC production of hepatocyte growth factor (HGF) and insulin-like growth factor-1 (IGF-1) were measured in vitro. RESULTS Hearts treated with WT MSCs exhibited the greatest functional recovery, and those treated with STAT3KO MSCs had equivalent recovery to vehicle. The highest proinflammatory cytokine levels were seen in vehicle-treated hearts, and the lowest in the WT MSC group. STAT3KO MSCs produced less IGF-1, but more HGF than WT MSCs. Finally, hearts treated with STAT3KO MSCs or vehicle had significantly higher caspase-3 levels than those treated with WT MSCs. CONCLUSIONS Intracoronary infusions of MSCs improve postischemic left ventricular function and reduce proapoptotic and proinflammatory signaling via a STAT3-dependent mechanism.

Surgical inpatient satisfaction: What are the real drivers?

BACKGROUND Inpatient satisfaction is a key element of hospital pay-for-performance programs. Communication and pain management are known to influence results, but additional factors may affect satisfaction scores. We tested the hypothesis that patient factors and outcome parameters not considered previously are clinically important drivers of inpatient satisfaction. METHODS Medical records were reviewed for 1,340 surgical patients who returned nationally standardized inpatient satisfaction questionnaires. These patients were managed by 41 surgeons in seven specialties at two academic medical centers. Thirty-two parameters based on the patient, surgeon, outcomes, and survey were measured. Univariate and multivariable analyses were performed. RESULTS Inpatients rated their overall experience favorably 75.7% of the time. Less-satisfied patients were more likely to be female, younger, less ill, taking outpatient narcotics, and admitted via the emergency department (all P < .02). Less-satisfied patients also were more likely to have unresected cancer (P < .001) or a postoperative complication (P < .001). The most relevant independent predictors of dissatisfaction in multivariable analyses were younger age, admission via the emergency department, preoperative narcotic use, lesser severity of illness, unresected cancer, and postoperative morbidity (all P < .01). CONCLUSION Several patient factors, expectations of patients with cancer, and postoperative complications are important and clinically relevant drivers of surgical inpatient satisfaction. Programs to manage expectations of cancer patient expectations and decrease postoperative morbidity should improve surgical inpatient satisfaction. Further efforts to risk-adjust patient satisfaction scores should be undertaken.

Systemic pretreatment with dimethyloxalylglycine increases myocardial HIF-1α and VEGF production and improves functional recovery after acute ischemia/reperfusion

BACKGROUND Stem cells protect the heart from ischemic damage in part by the release of cytoprotective growth factors, particularly vascular endothelial growth factor (VEGF). Production of VEGF is regulated in part by levels of the transcription factor hypoxia inducible factor 1-α (HIF-1α). Dimethyloxalylglycine (DMOG) prevents the deactivation of HIF-1α and increases VEGF production. However, the effects of systemic DMOG treatment on myocardial tolerance for ischemia are unknown. We hypothesized that systemic pretreatment with DMOG would improve myocardial ischemic tolerance. METHODS To study this hypothesis, adult male rats were randomly given an intraperitoneal injection of DMOG (40 mg/kg in 1 mL saline, n = 5) or saline (1 mL, n = 6) 24 h before cardiectomy and isolated heart perfusion. All hearts were subjected to 15 min equilibration, 25 min ischemia and 40 min reperfusion. Myocardial function was continuously monitored. Following reperfusion, myocardial homogenates were analyzed for HIF-1α and VEGF production. RESULTS We observed that hearts in the DMOG group exhibited greater recovery of left ventricular developed pressure LVDP, +dP/dt and -dP/dt. Myocardial HIF-1α and VEGF levels were increased by DMOG therapy. CONCLUSION In conclusion, systemic pretreatment with DMOG augments post-ischemic myocardial functional recovery through increased HIF-1α levels and greater VEGF production.

Female stem cells are superior to males in preserving myocardial function following endotoxemia

Mesenchymal stem cells (MSCs) may offer therapeutic benefit in the setting of sepsis and endotoxemia. Previous studies suggest that MSCs from female donors may possess better protective capabilities than their male counterparts. The present study examined whether female MSCs may offer a greater protective advantage in the setting of endotoxemic cardiac dysfunction compared with male MSCs. Adult male Sprague-Dawley rats were injected intraperitoneally with LPS and then treated with intraperitoneal injections of either saline, female MSCs, or male MSCs. Hearts and serum were then collected for analysis of myocardial function, myocardial protein, and myocardial and serum cytokines. Compared with male MSC or vehicle-treated animals, female MSC treatment resulted in greater preservation of myocardial function (P < 0.001). Serum and myocardial levels of all measured cytokines were comparable between rats given MSCs from male or female donors but substantially improved over rats given vehicle (P < 0.05). Reduced myocardial inflammation correlated with reduced levels of phosphorylated p38 MAPK expression in the myocardium of animals injected with MSCs of either sex (P < 0.05). The Bcl-xL/Bax ratio was increased to a greater extent following treatment with female MSCs vs. male MSCs (P < 0.05). Intraperitoneal administration of MSCs is effective in limiting myocardial inflammation and dysfunction in the rat endotoxemia model. Compared with treatment with their male counterparts, MSC treatment from female donors is associated with greater cardiac protection against acute endotoxemic injury.

Toll-like receptor 4 ablation improves stem cell survival after hypoxic injury

INTRODUCTION Mesenchymal stem cell (MSC) therapy improves cardiac function after ischemia/reperfusion injury, but its effectiveness is limited by MSC survival in hypoxic environments. Toll-like receptor 4 (TLR4) contributes to pro-apoptotic signaling under hypoxic conditions. Activation of intracellular AKT and ERK pathways opposes this signal and improves cell survival. It is unknown whether ablation of TLR4 affects these pathways after hypoxic injury in MSCs. We hypothesized that: 1) TLR4 knockout (TLR4KO) in MSCs improves survival after hypoxic injury; and 2) this survival difference is due to improved signaling in the AKT and ERK pathways. MATERIALS AND METHODS Murine wild-type (WT) and TLR4KO MSCs were harvested from bone marrow and grown in vitro. A total of 0.1 × 10(6) cells/well were incubated in hypoxic conditions versus normoxic controls. After 24 h, these groups were examined for cell survival via counting and compared using a t-test with P < 0.05 = statistical significance. AKT and ERK concentrations were measured in lysate using Western blot analysis. RESULTS The morphology of WT and TLR4KO MSCs was similar. In line with our previous findings, hypoxia did significantly increase cell death in WT cells (1.79 × 10(5) living cells/mL control versus 0.88 × 10(5) hypoxia, P < 0.05). Hypoxic injury did not increase cell death in the TLR4KO group (1.68 × 10(5) control versus 1.82 × 10(5) hypoxia, P < 0.05). Increased AKT activation was observed in all TLR4KO groups. TLR4 did not affect phosphorylated ERK levels. CONCLUSION TLR4-knockout MSCs show improved survival after hypoxic injury because of increased AKT pathway signal. Use of TLR4-knockout MSCs in ischemia/reperfusion studies results in enhanced cardioprotection; improved stem cell survival was likely a contributing factor.

Pretreatment with intracoronary mimosine improves postischemic myocardial functional recovery

BACKGROUND Cytoprotective growth factors such as vascular endothelial growth factor (VEGF) play important roles in myocardial protection from ischemia/reperfusion (I/R). Accumulating evidence suggests that the hypoxia-inducible factor 1 (HIF-1) pathway is a key regulator of VEGF production in the setting of I/R. The prolyl hydroxylase inhibitor mimosine can increase VEGF production through the HIF-1 pathway. We hypothesized that infusion of preischemic intracoronary mimosine would improve myocardial functional recovery after I/R. METHODS Isolated male rat hearts were subjected to 15 minutes of equilibration, 25 minutes of ischemia, and 40 minutes of reperfusion. Immediately prior to ischemia, ischemic hearts received intracoronary infusions of vehicle or solutions of 0.3, 3, or 30 μM mimosine. Myocardial function was recorded throughout the experiments. Functional data were analyzed with two-way analysis of variance adjusted with the Bonferroni correction. RESULTS Preischemic myocardial function was equivalent. All hearts had significant reductions in function at the beginning of reperfusion. Hearts treated with 0.3 or 3 μM mimosine infusions exhibited greater recovery of left ventricular developed pressure compared to vehicle. The maximal positive value of the first derivative of pressure (+dP/dt) was greater in hearts treated with 0.3 μM mimosine compared to hearts treated with vehicle. No differences were observed in recovery of end-diastolic pressure or the maximal negative value of the first derivative of pressure (-dP/dt). CONCLUSION Preischemic intracoronary mimosine infusion improves myocardial functional recovery after I/R.