To assess the safety and efficacy of the platelet-like nanoparticle (PLN), and to assess its safety in repeated administration.
6 purpose-bred dogs.
The PLN was administered IV at 3 different doses using a randomized crossover design. Each dog received a full dose of 8 X 1010 particles/10 kg, half dose, and 10 times the dose, with a 14-day washout period between doses. Biochemical, prothrombin time, partial thromboplastin time, and fibrinogen analyses were performed at baseline and 96 hours postinfusion. A CBC, kaolin-activated thromboelastography, platelet function assay closure time, and buccal mucosal bleeding time were performed at baseline and 1, 6, 24, 48, 72, and 96 hours postinfusion.
No significant changes were observed over time in the thromboelastography parameters, closure time, and buccal mucosal bleeding time. After the administration of the half dose, hematocrit levels decreased significantly at 1, 6, 24, 48, and 96 hours, with all values within the reference range. The platelet count was decreased significantly at hours 1, 6, 24, 48, and 72 after administration of the half dose, with values less than the reference range at all hours but hour 72. No significant changes in serum biochemistry, coagulation panel, and fibrinogen were observed for all doses. No adverse events were noted during the first infusion. Three dogs experienced transient sedation and nausea after repeat infusion.
The PLN resulted in a dilution of hematocrit and platelets, and did not significantly alter hemostasis negatively. The safety of repeated doses should be investigated further in dogs.
Objective—To assess platelet count, mean platelet volume (MPV), metabolic characteristics, and platelet function in a dimethyl sulfoxide (DMSO)–stabilized canine frozen platelet concentrate (PC).
Sample Population—11 units of a commercial frozen PC in 6% DMSO and fresh plateletrich plasma from 6 healthy control dogs.
Procedures—PCs were thawed, and the following data were collected: thaw time, platelet count, MPV, pH, PCO2, and PO2 and HCO3−, glucose, and lactate content. Phosphatidylserine translocation was determined by use of flow cytometry. Fresh platelet-rich plasma from healthy dogs served as a source of control platelets for flow cytometric analysis.
Results—At thaw, the platelet count in the frozen PC ranged from 243,000 to 742,000 platelets/μL. Median platelet count of paired samples was 680,000 platelets/μL and decreased significantly to 509,000 platelets/μL at 2 hours after thaw. Median MPV at thaw was 11.15 femtoliters and was stable after 2 hours. Compared with fresh platelets, frozen PC had increased amounts of phosphatidylserine in the outer leaflet of the platelet membrane in the resting (ie, not treated with thrombin) state (19% vs 99%, respectively) and alterations in cellular morphology, all of which were consistent with platelet activation.
Conclusions and Clinical Relevance—Results of this in vitro study indicated that there was a decrease in platelet quantity and function as well as an increase in platelet activation during the freeze-and-thaw process in DMSO-stabilized canine frozen PC. In vivo effects on PC remain to be determined.
OBJECTIVE To compare platelet function and viscoelastic test results between healthy dogs and dogs with chronic kidney disease (CKD) to assess whether dogs with CKD have platelet dysfunction and altered blood coagulation.
ANIMALS 10 healthy control dogs and 11 dogs with naturally occurring CKD.
PROCEDURES Blood and urine were collected once from each dog for a CBC, serum biochemical analysis, urinalysis, and determination of the urine protein-to-creatinine ratio, prothrombin time, activated partial thromboplastin time, plasma fibrinogen concentration, and antithrombin activity. Closure time was determined by use of a platelet function analyzer and a collagen-ADP platelet agonist. Thromboelastography (TEG) variables (reaction time, clotting time, α angle, maximum amplitude, and global clot strength [G value]) were determined by use of recalcified nonactivated TEG. Platelet expression of glycoprotein Ib (GPIb; receptor for von Willebrand factor), integrin αIIbβ3 (αIIbβ3; receptor for fibrinogen), and P-selectin (marker for platelet activation) was assessed by flow cytometry.
RESULTS Compared with healthy control dogs, the median closure time was prolonged, the median maximum amplitude and G value were increased, and the median clotting time was decreased for dogs with CKD. Platelet expression of both αIIbβ3 and P-selectin was also significantly increased for dogs with CKD, compared with that for control dogs. Platelet expression of GPIb, αIIbβ3, and P-selectin was not correlated with closure time or any TEG variable.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs with CKD frequently had evidence of platelet dysfunction and hypercoagulability that were not totally attributable to alterations in platelet surface expression of GPIb, αIIbβ3, and P-selectin.
To assess the effect of packed RBC (pRBC) transfusion on thromboelastographic (TEG) tracings in dogs with naturally occurring anemia.
22 clinically anemic dogs that received a pRBC transfusion.
For each dog, a blood sample was collected before and within 3 hours after completion of the pRBC transfusion for a CBC, nonactivated TEG analysis, and measurement of blood viscosity. Wilcoxon signed rank tests were used to compare CBC, viscosity, and TEG variables between pretransfusion and posttransfusion blood samples. Multivariable linear regression was used to assess the effects of pretransfusion-posttransfusion changes in Hct, WBC count, and platelet count on changes in TEG variables.
Median posttransfusion Hct (21%; range, 13% to 34%) was significantly greater than the median pretransfusion Hct (12.5%; range, 7% to 29%). Packed RBC transfusion was associated with a median increase in Hct of 6.2% (range, 1.2% to 13%). Maximum amplitude significantly decreased from 74.9 to 73.8 mm and clot strength significantly decreased from 14,906 to 14,119 dynes/s after pRBC transfusion. Blood viscosity significantly increased, whereas platelet and WBC counts significantly decreased after transfusion. Multivariable linear regression revealed that pretransfusion-posttransfusion changes in Hct, WBC count, and platelet count were not associated with changes in TEG variables.
CONCLUSIONS AND CLINICAL RELEVANCE
Results indicated that pRBC transfusion had only small effects on the TEG tracings of hemodynamically stable dogs. Therefore, large changes in TEG tracings following pRBC transfusion are unlikely to be the result of the transfusion and should be investigated further.
OBJECTIVE To evaluate the effects of damage-associated molecular patterns (DAMPs) derived from disrupted mitochondria on canine splenocytes and other immune cells.
SAMPLES Liver, spleen, and bone marrow samples obtained from 8 cadavers of healthy research Beagles that had been euthanized for other purposes.
PROCEDURES Mitochondria were obtained from canine hepatocytes, and mitochondrial DAMPs (containing approx 75% mitochondrial proteins) were prepared. Mitochondrial DAMPs and the nuclear cytokine high-mobility group box protein 1 were applied to splenocytes, bone marrow–differentiated dendritic cells, and a canine myelomonocytic cell (DH82) line for 6 or 24 hours. Cell culture supernatants from splenocytes, dendritic cells, and DH82 cells were assayed for tumor necrosis factor α with an ELISA. Expression of tumor necrosis factor α mRNA in splenocytes was evaluated with a quantitative real-time PCR assay.
RESULTS In all cell populations evaluated, production of tumor necrosis factor α was consistently increased by mitochondrial DAMPs at 6 hours (as measured by an ELISA). In contrast, high-mobility group box protein 1 did not have any independent proinflammatory effects in this experimental system.
CONCLUSIONS AND CLINICAL RELEVANCE The study revealed an in vitro inflammatory effect of mitochondrial DAMPs (containing approx 75% mitochondrial proteins) in canine cells and validated the use of an in vitro splenocyte model to assess DAMP-induced inflammation in dogs. This experimental system may aid in understanding the contribution of DAMPs to sepsis and the systemic inflammatory response syndrome in humans. Further studies in dogs are needed to validate the biological importance of these findings and to evaluate the in vivo role of mitochondrial DAMPs in triggering and perpetuating systemic inflammatory states.