Xenogeneic cardiac extracellular matrix scaffolds with or without seeded mesenchymal stem cells exhibit distinct in vivo immunosuppressive and regenerative properties.

Cardiac extracellular matrix (cECM) scaffolds are promising biomaterials for reconstructive surgery applications since they possess the structure/function properties of native tissue. Production of cECM scaffolds has been achieved using decellularization approaches, which commonly employ denaturing detergents, such as sodium dodecyl sulfate (SDS). Our antigen removal (AR) method has been shown to remove cellular and nonmyocyte components, while preserving cECM scaffold structure/function relationships. Here, we demonstrate that more human mesenchymal stem cells (MSCs) invaded AR scaffolds compared to SDS controls. Additionally, AR scaffolds stimulated a constructive remodeling response similar to allograft controls, and were transformed to adipose tissue in a xenogeneic rat to mouse subpannicular in vivo model. Conversely, SDS scaffolds showed a chronic inflammatory response that worsened throughout the 12-wk time course preventing constructive remodeling and mirroring the response seen towards xenogeneic tissue. AR scaffolds and xenogeneic controls recellularized with murine MSCs (mMSCs) were also implanted to assess whether mMSCs would offer any additive benefit in overcoming residual scaffold-specific immune responses. Paradoxically, recellularization resulted in chronic inflammatory response in AR-recellularized scaffolds. We conclude that AR cECM scaffolds represent a promising biomaterial, which is accepted by the recipient as self in origin and fosters implantation site appropriate regenerative responses. STATEMENT OF SIGNIFICANCE: We demonstrated that an antigen-removal (AR) approach utilizing principles of differential solubility for production of a xenogeneic rat cardiac extracellular matrix scaffold results in improved recellularization efficiency with human and mouse mesenchymal stem cells (MSCs) in vitro. Furthermore, we tested the immune response to AR scaffolds versus allograft and xenograft controls with or without MSC recellularization using a rat to mouse subcutaneous model. We showed that AR scaffolds and allograft controls resulted in significant adipose tissue transformation after 12weeks. Paradoxically, MSCs had a positive impact in the immune response to xenografts, but had the opposite effect in AR scaffolds, resulting in chronic inflammatory response, which might be attributed to a change of their phenotype following recellularization into scaffolds.

Mesenchymal Stem Cell Seeding of Porcine Small Intestinal Submucosal Extracellular Matrix for Cardiovascular Applications.

In this study, we investigate the translational potential of a novel combined construct using an FDA-approved decellularized porcine small intestinal submucosa extracellular matrix (SIS-ECM) seeded with human or porcine mesenchymal stem cells (MSCs) for cardiovascular indications. With the emerging success of individual component in various clinical applications, the combination of SIS-ECM with MSCs could provide additional therapeutic potential compared to individual components alone for cardiovascular repair. We tested the in vitro effects of MSC-seeding on SIS-ECM on resultant construct structure/function properties and MSC phenotypes. Additionally, we evaluated the ability of porcine MSCs to modulate recipient graft-specific response towards SIS-ECM in a porcine cardiac patch in vivo model. Specifically, we determined: 1) in vitro loading-capacity of human MSCs on SIS-ECM, 2) effect of cell seeding on SIS-ECM structure, compositions and mechanical properties, 3) effect of SIS-ECM seeding on human MSC phenotypes and differentiation potential, and 4) optimal orientation and dose of porcine MSCs seeded SIS-ECM for an in vivo cardiac application. In this study, histological structure, biochemical compositions and mechanical properties of the FDA-approved SIS-ECM biomaterial were retained following MSCs repopulation in vitro. Similarly, the cellular phenotypes and differentiation potential of MSCs were preserved following seeding on SIS-ECM. In a porcine in vivo patch study, the presence of porcine MSCs on SIS-ECM significantly reduced adaptive T cell response regardless of cell dose and orientation compared to SIS-ECM alone. These findings substantiate the clinical translational potential of combined SIS-ECM seeded with MSCs as a promising therapeutic candidate for cardiac applications.

Retrospective review of unintentional pediatric ingestions of doxylamine.

BACKGROUND: Doxylamine is a first-generation antihistamine similar in structure to diphenhydramine. Unlike diphenhydramine, however, there is a paucity of data regarding the risk of toxicity following unintentional exposures in pediatric patients. METHODS: We performed an observational case series with data collected retrospectively from a poison system database for all single-substance pediatric (5 years-old and younger) doxylamine ingestions for the period of 1997-2012. Data collected included age, gender, weight, reason for exposure, exact or estimated maximum dose, clinical effects and medical interventions. RESULTS: A total of 140 cases were identified; 74 (53%) involved males. Ages ranged 6 months to 5 years. In 30 cases (21%), the exact amount ingested was documented and ranged from 6.25-50 mg with a maximum weight-based dose of 6.2 mg/kg. In 76 cases, the estimated maximum dose ranged from 12.5 to 375 mg with a maximum weight-based dose of 37 mg/kg. All symptoms were mild and self-limiting. The only documented intervention was the administration of activated charcoal in 13 cases. CONCLUSION: Unintentional isolated pediatric doxylamine ingestions did not result in significant toxicity in our 140 cases. Reported doses of up to 6.2 mg/kg resulted in only transient drowsiness and tachycardia.

Examining the risk of methanol poisoning from methyl acetate-containing products.

OBJECTIVES: This retrospective study aims to review California Poison Control System data to qualitatively describe reported methyl acetate (MA) exposures and determine if a metabolic acidosis develops. METHODS: We queried the Poison Control System data between January 1997 and December 1, 2010. Inclusion criteria were single MA ingestions. RESULTS: Eighty-three cases were analyzed. Females made up 52% of study subjects. Seventy-five cases (90%) were 5 years or younger. Most (93%) ingestions were unintentional. Sixty-two cases (75%) were referred to a health care facility (HCF). Of these, 75% of cases referred to an HCF had no effect, and 25% of cases had a minor effect. There were no major effects, including deaths reported. One case received single-dose activated charcoal, and 1 case received intravenous fluids as therapy. All other cases were observed only. Of all cases, including home-managed and HCF cases, 63 (76%) had no symptoms. Vomiting was observed in 12 cases (14%), drowsiness in 1 case, ataxia in 1 case, abdominal pain in 1 case, and throat/oral irritation in 5 cases. Fifty-three percent of cases referred to HCF had at least 1 chemistry panel done (27% had >1 chemistry panel done). One patient had a mild metabolic acidosis without symptoms that resolved after a period of observation. There was no renal dysfunction. CONCLUSION: These data suggest that minor ingestions of MA may be observed at home, but a prospective study is needed to exclude the risk of home observation.

A retrospective review of isolated duloxetine-exposure cases.

BACKGROUND: Duloxetine is a serotonin norepinephrine reuptake inhibitor (SNRI) approved in the US for the treatment of major depression, generalized anxiety, fibromyalgia, diabetic peripheral neuropathy, and chronic musculoskeletal pain. Given the limited published information regarding human overdoses to this medication, our goal was to characterize such exposures. METHODS: We retrospectively reviewed a state poison system's database for all single agent exposures to duloxetine from 2004-2011. Data collected included age, gender, circumstances surrounding exposure, symptoms, and outcome. Patients with co-ingestants, confirmed non-exposure, unknown outcomes, or other coding errors were excluded. RESULTS: 159 cases were identified. 106 were included for review. Of 61 pediatric and adolescent cases (0-19 years old) identified, 53 involved unintentional overdose. Three patients experienced symptoms and none were admitted. All intentional ingestions(8) were seen in the emergency department, two patients experienced symptoms. No intentional ingestion was admitted for medical care. Fifty-one adult cases were included for review. Four adult patients were admitted following intentional duloxetine overdose with resolution of symptoms within 24 hours. Three adults were evaluated in a HCF following non-self-harm exposures to duloxetine. None of these patients were admitted. The remaining 15 adult patients with non-self-harm exposures were safely managed at home. CONCLUSION: The majority of non-self-harm duloxetine-exposed adult and pediatric/adolescent patients were safely managed at home and when evaluated in a healthcare facility, did not require further hospitalization. Intentional pediatric/adolescent and adult duloxetine exposures were managed in a healthcare facility but rarely resulted in further hospitalization, serious morbidity, or mortality.

A retrospective poison center review of varenicline-exposed patients.

BACKGROUND: Varenicline was approved by the Food and Drug Administration (FDA) as a prescription smoking cessation aid in May 2006. Varenicline is both a partial nicotine agonist and an antagonist. Recent reports by the Institute of Safe Medication Practices identified safety problems associated with varenicline use, and the FDA recently issued a boxed warning. These safety concerns regarding varenicline use prompted this study. OBJECTIVE: To characterize varenicline-exposed patients as reported to a poison control system. METHODS: We performed a retrospective search of the California Poison Control System electronic database from August 2006 through August 2008, using the term varenicline or Chantix. Cases matching these results were reviewed. All ages were included. Excluded were patients with coingestants and unknown outcomes. Clinical parameters and medical outcomes were extracted from the database. RESULTS: Thirty-six cases met inclusion criteria and 17 cases were excluded, Ten cases involved nonpediatric patients; 9 cases involved patients less than 6 years old, which were defined as pediatric patients. The median duration of poison center follow-up for pediatric patients was 253 minutes; median duration of follow-up for nonpediatric patients with unintentional exposures was 28.5 minutes. The majority of exposures were unintentional and included all the pediatric patients and 6 nonpediatric patients who had unintentional medication errors. Gastrointestinal and neuropsychiatric adverse events were most frequently reported. The majority of these patients were managed at home. Among those evaluated at a healthcare facility, only 1 pediatric patient was admitted. Of the remaining patients, 1 nonpediatric patient reported a deliberate exposure and 3 nonpediatric patients experienced adverse effects at therapeutic doses. Median duration of follow-up for these patients was 308 minutes. CONCLUSIONS: Patients exposed to varenicline in our study had favorable outcomes. Gastrointestinal and neuropsychiatric effects were the most commonly reported adverse events. A dose-response relationship could not be determined and triage criteria to a healthcare facility remain undetermined.