@article{moiseiwitsch_nellenbach_downey_boorman_brown_guzzetta_2023, title={Influence of Fibrinogen Concentrate on Neonatal Clot Structure When Administered Ex Vivo After Cardiopulmonary Bypass}, volume={137}, ISSN={["0003-2999"]}, DOI={10.1213/ANE.0000000000006357}, abstractNote={BACKGROUND: Bleeding is a serious complication of cardiopulmonary bypass (CPB) in neonates. Blood product transfusions are often needed to adequately restore hemostasis, but are associated with significant risks. Thus, neonates would benefit from other effective, and safe, hemostatic therapies. The use of fibrinogen concentrate (FC; RiaSTAP, CSL Behring, Marburg, Germany) is growing in popularity, but has not been adequately studied in neonates. Here, we characterize structural and degradation effects on the neonatal fibrin network when FC is added ex vivo to plasma obtained after CPB. METHODS: After approval by the institutional review board and parental consent, blood samples were collected from neonates undergoing cardiac surgery and centrifuged to yield platelet poor plasma. Clots were formed ex vivo from plasma obtained at several time points: (1) baseline, (2) immediately post-CPB, and (3) post-transfusion of cryoprecipitate. In addition, we utilized post-CPB plasma to construct the following conditions: (4) post-CPB +0.5 mg/mL FC, and (5) post-CPB +0.9 mg/mL FC. The resultant fibrin networks were imaged using confocal microscopy to analyze overall structure, fiber density, and alignment. Clots were also analyzed using a microfluidic degradation assay. Fibrinogen content was quantified for all plasma samples. RESULTS: The addition of 0.5 or 0.9 mg/mL FC to post-CPB samples significantly enhanced the median fiber density when compared to untreated post-CPB samples (post-CPB = 0.44 [interquartile range {IQR}: 0.36–0.52], post-CPB +0.5 mg/mL FC = 0.69 [0.56–0.77], post-CPB +0.9 mg/mL FC = 0.87 [0.59–0.96]; P = .01 and P = .006, respectively). The addition of 0.9 mg/mL FC to post-CPB samples resulted in a greater fiber density than that observed after the in vivo transfusion of cryoprecipitate (post-transfusion = 0.54 [0.45–0.77], post-CPB +0.9 mg/mL FC = 0.87 [0.59–0.96]; P = .002). Median fiber alignment did not differ significantly between post-CPB samples and samples treated with FC. Degradation rates were not statistically significant from baseline values with either 0.5 or 0.9 mg/mL FC. In addition, we found a significant correlation between the difference in the baseline and post-CPB fibrinogen concentration with patient age (P = .033) after controlling for weight. CONCLUSIONS: Our results show that clots formed ex vivo with clinically relevant doses of FC (0.9 mg/mL) display similar structural and degradation characteristics compared to the in vivo transfusion of cryoprecipitate. These findings suggest that FC is effective in restoring structural fibrin clot properties after CPB. Future studies after the administration of FC in vivo are needed to validate this hypothesis.}, number={3}, journal={ANESTHESIA AND ANALGESIA}, author={Moiseiwitsch, Nina and Nellenbach, Kimberly A. and Downey, Laura A. and Boorman, David and Brown, Ashley C. and Guzzetta, Nina A.}, year={2023}, month={Sep}, pages={682–690} }
 @article{moiseiwitsch_zwennes_szlam_sniecinski_brown_2022, title={COVID-19 patient fibrinogen produces dense clots with altered polymerization kinetics, partially explained by increased sialic acid}, ISSN={["1538-7836"]}, DOI={10.1111/jth.15882}, abstractNote={Thrombogenicity is a known complication of COVID‐19, resulting from SARS‐CoV‐2 infection, with significant effects on morbidity and mortality.}, journal={JOURNAL OF THROMBOSIS AND HAEMOSTASIS}, author={Moiseiwitsch, Nina and Zwennes, Nicole and Szlam, Fania and Sniecinski, Roman and Brown, Ashley}, year={2022}, month={Oct} }
 @article{moiseiwitsch_nellenbach_guzzetta_brown_downey_2021, title={Ex Vivo and In Vivo Evaluation of Fibrinogen Concentrate to Mitigate Post-Surgical Bleeding in Neonates}, volume={138}, ISSN={["1528-0020"]}, DOI={10.1182/blood-2021-153823}, abstractNote={
 Introduction: Bleeding is a serious complication among neonates undergoing cardiopulmonary bypass (CPB) and it is linked to significant morbidity and mortality. Current standard of care treatment for bleeding after CPB focuses on the transfusion of adult blood products, including platelets and cryoprecipitate. However, prior work by Nellenbach et al. has demonstrated structural differences between neonatal and adult clotting components. Importantly, neonatal and adult fibrin do not fully integrate during clot formation which may contribute to ineffective clot formation and/or increased thrombotic risk following transfusion of adult cryoprecipitate to neonates. There has been increased interest in using human fibrinogen concentrate (HFC) in treating bleeding in the post-CPB neonate; however, HFC has not been validated in this population through evidence-based means. This study analyzed structural and degradation properties of post-CPB clots +/- the ex vivo addition of HFC and compared structural and degradation properties of post-CPB clots after the in vivo transfusion of HFC versus cryoprecipitate.
 Methods: Human neonatal plasma samples were collected from patients undergoing CPB at the Children's Hospital of Atlanta. For ex vivo studies, samples were taken at baseline, post-bypass, and post-transfusion of cryoprecipitate (n = 18 patients). Clots were formed for analysis from samples alone as well as post-bypass samples with the addition of 0.5 or 0.9 mg/mL HFC (RiaSTAP, CSL Behring) and structure was examined through confocal microscopy. Clot degradation was assessed through a microfluidic fibrinolysis assay. For in vivo studies, samples were taken at baseline, post-transfusion of cryoprecipitate or HFC, upon ICU arrival, and at 24 hours post-surgery (n = 36 patients). Clots were formed from samples and structure was examined through confocal microscopy. Clot degradation was assessed through a plate-based fibrinolysis assay.
 Results: In ex vivo studies, clot structural analysis demonstrated no significant differences in fiber density between samples collected at different time points (baseline = 0.541 ± 0.105, post-bypass = 0.431 ± 0.111, post-transfusion = 0.594 ± 0.170). The addition of 0.5 mg/mL or 0.9 mg/mL HFC to post-bypass samples led to a significant increase in fiber density (0.5 mg/mL HFC=0.654 ± 0.158, p=0.02; 0.9 mg/mL HFC= 0.797 ± 0.193, p<0.0001). Functional microfluidic analysis of clot degradation demonstrated significantly faster degradation times among post-bypass samples when compared to baseline samples (baseline degradation rate = 11.061 ± 6.087, post-bypass degradation rate = 25.906 ± 9.990 microns/hour, p=0.04). The addition of 0.5 mg/mL HFC resulted in a slower degradation rate from the original post-CPB degradation rate, but did not reach statistical significance (0.5 mg/mL HFC=14.091 ± 2.241, p=0.14). However, the addition of 0.9 mg/mL HFC resulted in a significantly slower degradation rate (0.9 mg/mL HFC=8.594 ± 6.087, p=0.01). Studies comparing in vivo transfusion of cryoprecipitate and HFC demonstrated no significant difference between treatment groups in clot density or degradation rate for any sample time point.
 Conclusion: We identify patterns in structural properties of clots formed after the transfusion of HFC that are consistent with successful hemostasis. However, caution is warranted regarding potentially thrombotic risks and should be carefully analyzed in future studies.
 Figure: Effect of Ex Vivo HFC Addition on Clot Structure and Degradation. (A) Representative confocal imaging of clots formed from different samples and HFC dosages (scale = 50 um). (B) Effect of HFC Addition on Clot Fiber Density. Addition of both 0.5 and 0.9 mg/mL HFC dosages to post-bypass sample result in statistically significant increases in fiber density compared to post-bypass samples. (C) Effect of HFC Addition on Clot Degradation Profiles. Addition of 0.9 mg/mL HFC to post-bypass sample leads to statistically significant slower fibrinolysis.
 Figure 1 Figure 1.
 
 
 
 Brown: Selsym Biotech, Inc.: Other: Co-Founder and CEO.
 
 
 
 RiaSTAP (human fibrinogen concentrate) is FDA approved for the treatment of congenital hypofibrinogenemia.
}, journal={BLOOD}, author={Moiseiwitsch, Nina and Nellenbach, Kimberly A. and Guzzetta, Nina A. and Brown, Ashley C. and Downey, Laura}, year={2021}, month={Nov} }
 @article{mihalko_nellenbach_krishnakumar_moiseiwitsch_sollinger_cooley_brown_2021, title={Fibrin-specific poly(N-isopropylacrylamide) nanogels for targeted delivery of tissue-type plasminogen activator to treat thrombotic complications are well tolerated in vivo}, ISSN={["2380-6761"]}, DOI={10.1002/btm2.10277}, abstractNote={Abstract Targeted drug delivery for maintaining blood fluidity can reduce the risks associated with systemic anticoagulants that can lead to off‐target bleeding. Recently, there has been much interest in targeted delivery of tissue‐type plasminogen activator (tPA) for treating thrombotic complications. The work presented here characterizes a fibrin‐specific nanogel (FSN) design for targeted delivery of tPA to treat thrombotic complications. Fibrin binding and clot degradation were characterized in vitro, and animal models of thrombosis were used to examine nanogel effects on coagulation parameters. In vitro assays showed tPA‐FSNs attach to fibrin in a dose‐dependent manner independent of tPA loading. In animal models of thrombosis, including an electrolytic injury to monitor clot properties in real time, and a lipopolysaccharide‐induced disseminated intravascular coagulation (DIC) animal model, tPA‐FSNs modulated fibrin/fibrinogen and platelet incorporation into clots and at optimized dosing could recover consumptive coagulopathy in DIC. Distribution of unloaded and tPA‐loaded FSNs showed potential clearance of tPA‐FSNs after 24 h, although unloaded FSNs may be retained at sites of fibrin deposits. Maximum tolerated dose studies showed tPA‐FSNs have minimal toxicity up to 20 times the optimized therapeutic dose. Overall, these studies demonstrate the therapeutic efficacy of targeted fibrinolysis for systemic microthrombi and begin to evaluate key translational parameters for tPA‐FSN therapeutics, including optimal tPA‐FSN dosage in a DIC rodent model and safety of intravenous tPA‐FSN therapeutics.}, journal={BIOENGINEERING & TRANSLATIONAL MEDICINE}, author={Mihalko, Emily P. and Nellenbach, Kimberly and Krishnakumar, Manasi and Moiseiwitsch, Nina and Sollinger, Jennifer and Cooley, Brian C. and Brown, Ashley C.}, year={2021}, month={Dec} }
 @misc{moiseiwitsch_brown_2021, title={Neonatal coagulopathies: A review of established and emerging treatments}, volume={246}, ISSN={["1535-3699"]}, DOI={10.1177/15353702211006046}, abstractNote={Despite the relative frequency of both bleeding and clotting disorders among patients treated in the neonatal intensive care unit, few clear guidelines exist for treatment of neonatal coagulopathies. The study and treatment of neonatal coagulopathies are complicated by the distinct hemostatic balance and clotting components present during this developmental stage as well as the relative scarcity of studies specific to this age group. This mini-review examines the current understanding of neonatal hemostatic balance and treatment of neonatal coagulopathies, with particular emphasis on emerging treatment methods and areas in need of further investigative efforts.}, number={12}, journal={EXPERIMENTAL BIOLOGY AND MEDICINE}, author={Moiseiwitsch, Nina and Brown, Ashley C.}, year={2021}, month={Jun}, pages={1447–1457} }