Parameters of Hemostasis in Sheep Implanted with Composite Scaffold Settled by Stimulated Mesenchymal Stem Cells-Evaluation of the Animal Model.

Implantation of composite scaffolds could be potentially associated with the risk of hemostatic disturbances in a recipient. However, there is a lack of information on possible alterations in clotting mechanisms resulting from such a procedure. The aim of the present work was to investigate changes in hemostatic parameters in sheep implanted with a scaffold composed of poly(ε-caprolactone) and hydroxyapatite and tricalcium phosphate (9:4.5:4.5), settled previously with mesenchymal stem cells stimulated by fibroblast growth factor-2 and bone morphogenetic protein-2. Nine Merino sheep were examined for 7 days, and measurements of clotting times (PT, aPTT), activities of antithrombin, protein C and clotting factors II-XII, and concentrations of fibrinogen and D-dimer were carried out before and 1 h, 24 h, 3 days and 7 days after scaffold implantation. The introduction of scaffold initially resulted in a slowdown of the clotting processes (most evident 24 h after surgery); PT and aPTT increased to 14.8 s and 33.9 s, respectively. From the third day onwards, most of these alterations began to return to normal values. The concentration of fibrinogen rose throughout the observation period (up to 8.4 g/L), mirroring the ongoing inflammatory reaction. However, no signals of significant disturbances in hemostatic processes were detected in the sheep tested.

Involvement of hemostasis in pathophysiology of RAO in horses.

Recurrent Airway Obstruction (RAO), also called severe asthma or heaves, is a chronic disease in adult horses caused by aeroallergens from straw or hay. Disturbances in hemostasis (intensified coagulation and depressed fibrinolysis) are considered one of the prominent reasons of inflammatory process, injury and dysfunction of the lungs. The aim of the study was to evaluate chosen parameters of hemostasis in horses with active form of RAO. Ten RAO-horses (group R) and ten healthy horses (group C) were exposed to straw and hay allergen challenge. The prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time (TT), fibrinogen concentration (Fb), stabilized fibrin degradation product (d-dimer), antithrombin (AT), protein C and coagulation factors II through XII were assessed in plasma obtained from blood of all the horses. Exposure to aeroallergens resulted in prolongation of aPTT in both groups of animals; it was evident in the group R and moderate in the group C. There were no differences in PT and TT. Concentrations of fibrinogen and d-dimer and activity of protein C in both groups were increased but lay within or near to reference values. The activity of AT was depressed in RAO-horses. All exposed horses showed increased activity of coagulation factors II, VIII and X but they had no changes in activity of factor V. Factors VII and XII displayed a reduction in activity. The decrease in factor IX activity was noted in the group C only. Various changes were observed in activity of factor XI; in horses with RAO it was elevated but in healthy horses it was declined. The changes of the parameters tested in RAO-horses indicate the involvement of coagulation and fibrinolysis which apparently remained under control of efficient and active mechanisms of general hemostasis.

Age-related changes of platelet and plasma coagulation parameters in young pigs.

The literature on hemostatic processes in swine is sparse and often fragmentary; hence, we conducted our study to characterize age-related changes in selected parameters of primary and secondary hemostasis in 50 growing pigs between day 2 and week 24 of age. We measured platelet count (PLT), mean platelet volume, platelet-to-large cell ratio, prothrombin time, activated partial thromboplastin time (aPTT), thrombin time (TT), and fibrinogen concentration. Among primary hemostasis parameters, PLT underwent the largest fluctuation with the animals' age, ranging from 340 to 730 × 10(9)/L. However, statistical significance was only detected for 4-week-old piglets compared to 18-week-old animals. Of the secondary hemostasis parameters measured, TT and aPTT were the most changeable. Activated partial thromboplastin time displayed a characteristic biphasic course, being relatively short before week 5 of age (17.8-19.9 s) and then becoming much longer (28.7-52.5 s). The aPTTs measured in animals 6 weeks of age and older were statistically different (p < 0.01) from those in younger piglets. The 2 main components of hemostasis, platelet hemostasis and plasma coagulation, did not develop at the same time. It took much longer for secondary hemostasis to stabilize, whereas platelet parameters were stable early in life.