Platelet function testing in pigs using the Multiplate® Analyzer

Advances in Platelet-Dysfunction Diagnostic Technologies

The crucial role of platelets in hemostasis and their broad implications under various physiological conditions underscore the importance of accurate platelet-function testing. Platelets are key to clotting blood and healing wounds. Therefore, accurate diagnosis and management of platelet disorders are vital for patient care. This review outlines the significant advancements in platelet-function testing technologies, focusing on their working principles and the shift from traditional diagnostic methods to more innovative approaches. These improvements have deepened our understanding of platelet-related disorders and ushered in personalized treatment options. Despite challenges such as interpretation of complex data and the costs of new technologies, the potential for artificial-intelligence integration and the creation of wearable monitoring devices offers exciting future possibilities. This review underscores how these technological advances have enhanced the landscape of precision medicine and provided better diagnostic and treatment options for platelet-function disorders.

Comparison of artery diameters in the Aachen minipig serving as a human intracranial in vivo model

Minipigs are used as in vivo endovascular models, particularly in stroke and aneurysm research. However, detailed knowledge of the diameters of forelimb arteries that are commonly used as surrogates for human brain-supplying arteries are lacking. This study aimed to determine the diameters of forelimb and neck arteries in Aachen minipigs and to compare those to the diameters of human cerebral brain-supplying arteries in order to assess the validity of the Aachen minipig as a human intracranial in vivo model. We measured the diameters in the external carotid artery and eight different branches of the subclavian artery in 12 Aachen minipigs using angiographic imaging. Analysed arteries comprised the external carotid artery, axillary artery, brachial artery, subscapular artery first segment, subscapular artery second segment, external thoracic artery, caudal circumflex humeral artery, suprascapular artery and thoracodorsal artery. We compared these diameters to diameters of the following human brain-supplying arteries: terminal internal carotid artery (carotid-T and petrous segment), M1 segment of the middle cerebral artery, M2 segments of the middle cerebral artery, anterior cerebral artery, vertebral artery and basilar artery. Median diameters of porcine forelimb arteries ranged from 1.8 to 4.9 mm, and human brain supplying arteries ranged in diameter from 1.4 to 4.3 mm. Depending on the intended use, this allows porcine forelimb arteries to be selected which are statistically comparable to human brain-supplying vessels. In conclusion, we identified several equivalent arteries of the porcine subclavian branches that are comparable to human brain-supplying arteries. This may help to validate the minipig as a suitable in vivo model for neurovascular experiments.

Treatment of Ulcerative Colitis: Impact on Platelet Aggregation

Background and Objectives: Ulcerative colitis is chronic and/or progressive inflammation of the colorectal mucosa and submucosa and represents one of two major inflammatory bowel diseases. Ulcerative colitis has been associated with increased risk of arteriosus and venous thrombosis. There are numerous factors responsible for this; one of them is platelet activation and aggregation. The objective of our study was to determine if different treatment options for ulcerative colitis have an impact on platelet aggregation. Materials and Methods: This research was a prospective, observational study and included 94 newly diagnosed patients with UC divided into four treatment groups. For all patients, we measured platelet aggregability by using an impedance aggregometry method with a multiplate analyzer before and after treatment with infliximab, adalimumab, vedolizumab and azathioprine. A Paired Samples t test was performed in order to determine the difference in platelet aggregability before and after a certain therapy, since the data followed a normal distribution. Taking into account the impact of some clinical characteristics, multiple linear regression was conducted for the purpose of estimating the effect of therapy on the level of reduction in platelet aggregability. Results: All four drugs significantly reduced platelet aggregability. After we excluded the influence of clinical and endoscopic scores and disease localization on the results, we found that infliximab had the greatest anti-platelet activity. Conclusions: In addition to the well-known traditional risk factors for atherosclerosis, activation and aggregation of platelets play a significant role in the development of arterial thrombosis, and our results suggested that therapy use for the treatment of UC, especially infliximab, can have a great impact on cardiovascular morbidity and mortality by decreasing platelet aggregability.

Platelet function testing using the Multiplate analyzer after administration of aspirin in Aachen minipigs

Knowledge of platelet function in pigs and the effectiveness of antiplatelet therapy is important to ensure proper transferability from animal studies to humans. Our aim was to (1) characterize baseline platelet function of Aachen minipigs using the bedside Multiplate analyzer, (2) compare baseline platelet function with Göttingen minipigs, and (3) characterize platelet inhibition within the first 5 minutes after intravenous administration of acetylsalicylic acid (ASA). We characterized the baseline platelet function and hematological parameters in 9 Aachen minipigs. Historical data of 8 unmedicated Göttingen minipigs were used for comparison of baseline values. Platelet inhibition in Aachen minipigs was tested 1-5 minutes after intravenous administration of 500 mg ASA. Multiplate examinations included the following tests: ASPI test (to assess the effect of ASA), adenosine-diphosphate-test (ADP test) and thrombin receptor activating peptide test (TRAP test). Median values and interquartile range (IQR) of the Multiplate baseline tests in Aachen minipigs were as follows: ASPI: 39 U (IQR = 21-71), ADP: 70 U (IQR = 48-73), and TRAP: 8 U (IQR = 6-9), whereas the values in Göttingen minipigs were as follows: ASPI: 70.5 U (IQR = 60-78), ADP: 51 U (IQR = 45-66), and TRAP: 6.5 U (IQR = 4-8). ASPI values of Göttingen minipigs were significantly higher than those of Aachen minipigs (p = 0.046). Intravenous administration of ASA in Aachen minipigs resulted in significant platelet inhibition after 1 minute, which remained stable over a period of 5 minutes (p≤0.038). Aachen minipigs appeared to have a high variance in arachidonic acid-mediated platelet aggregation. In Aachen minipigs, intravenous ASA administration resulted in immediate platelet inhibition.

Microbiota-Derived Propionate Modulates Megakaryopoiesis and Platelet Function

Rheumatoid arthritis (RA) is associated with an increased risk for cardiovascular events driven by abnormal platelet clotting effects. Platelets are produced by megakaryocytes, deriving from megakaryocyte erythrocyte progenitors (MEP) in the bone marrow. Increased megakaryocyte expansion across common autoimmune diseases was shown for RA, systemic lupus erythematosus (SLE) and primary Sjögren’s syndrome (pSS). In this context, we evaluated the role of the microbial-derived short chain fatty acid (SCFA) propionate on hematopoietic progenitors in the collagen induced inflammatory arthritis model (CIA) as we recently showed attenuating effects of preventive propionate treatment on CIA severity. In vivo, propionate treatment starting 21 days post immunization (dpi) reduced the frequency of MEPs in the bone marrow of CIA and naïve mice. Megakaryocytes numbers were reduced but increased the expression of the maturation marker CD61. Consistent with this, functional analysis of platelets showed an upregulated reactivity state following propionate-treatment. This was confirmed by elevated histone 3 acetylation and propionylation as well as by RNAseq analysis in Meg-01 cells. Taken together, we identified a novel nutritional axis that skews platelet formation and function.

The porcine abattoir blood model-Evaluation of platelet function for in-vitro hemocompatibility investigations

BACKGROUND

The major obstacle of blood-contacting medical devices is insufficient hemocompatibility, particularly thrombogenicity and platelet activation. Pre-clinical in-vitro testing allows for the evaluation of adverse thrombogenicity-related events, but is limited, among others, by the availability and quantity of human blood donations. The use of animal blood is an accepted alternative for several tests; however, animal and particularly abattoir blood might present species-specific differences to human blood as well as elevated blood values, and pre-activated platelets due to stressed animals and non-standardized blood collection.

MATERIAL & METHODS

To this end, we investigated porcine abattoir blood in comparison to human donor blood with the focus on platelet pre-activation and remaining activation potential. By means of light transmission aggregometry, aggregation kinetics of platelet rich plasma after stimulation with three different concentrations of each adenosine diphosphate (ADP) (5 µM, 10 µM, 20 µM) and collagen (2.5 µg/ml, 5 µg/ml, 10 µg/ml) were monitored.

RESULTS

The activation with collagen revealed no significant differences in platelet behavior of the two species. In contrast, stimulation with ADP resulted in a lower maximum aggregation and a high disaggregation for porcine abattoir blood. The latter is a species-specific phenomenon of porcine platelets. Variations within each study cohort were comparable for human and abattoir pig.

CONCLUSION

The similarities in platelet activation following collagen stimulation and the preservation of the porcine-specific reaction to ADP prove a general functionality of the abattoir blood. This finding provides a first step towards the complete validation of the porcine abattoir blood model.

Whole blood platelet impedance aggregometry with the ROTEM platelet device: comparison of 2 anticoagulants and storage times for the establishment of canine reference intervals

The ROTEM platelet device, a point-of-care whole blood platelet impedance aggregometer, is an add-on to the rotational thromboelastometry ROTEM delta device. The latter has been validated in dogs. We examined whether canine whole blood is suited for analysis with the ROTEM platelet device using adenosine-5'-diphosphate (ADP) and arachidonic acid (ARA) as agonists for platelet activation, and if there are significant differences between sample storage times and anticoagulants used. Subsequently, we determined canine reference intervals (RIs) for the ROTEM platelet device for ADP and ARA. In a pilot study, we examined whole blood from 7 dogs after 15-min and 60-min storage of lithium-heparinized samples and 40-min and 80-min storage of hirudinized samples. Statistical analysis showed no significant differences between ROTEM platelet device results for both ADP and ARA in lithium-heparin and hirudin anticoagulated canine whole blood. Lithium-heparinized blood samples analyzed after 15-min storage had the lowest coefficient of variation. RIs were determined for heparinized whole blood samples from 49 dogs after 15 min of storage.

Resuscitative endovascular balloon occlusion of the aorta for thoracic trauma in the setting of platelet dysfunction: A translational swine study

BACKGROUND

In patients with noncompressible torso hemorrhage, antiplatelet medications may lead to worse outcomes. Resuscitative endovascular balloon occlusion of the aorta (REBOA) may potentially stabilize these patients, but currently, major thoracic bleeding is a contraindication. The goal of this study was to determine if REBOA use for shock with major thoracic bleeding has worse outcomes in the setting of platelet dysfunction (PD).

METHODS

Forty-one male Yorkshire swine (60-80 kg) underwent a 30% hemorrhage and then were randomized to three thoracic injuries, with and without zone 1 REBOA occlusion: pulmonary parenchymal injury (PI), thoracic venous injury (VI), or subclavian artery injury (AI). All animals were given aspirin to produce PD. Following hemorrhage, thoracic injuries were induced (T0) and allowed to bleed freely. Resuscitative endovascular balloon occlusion of the aorta groups had zone 1 occlusion, with deflation at T30. All groups received whole blood resuscitation at T30 and were euthanized at T90. Survival, total blood loss, hemodynamics, and arterial blood gas parameters were analyzed.

RESULTS

The PD-VI-REBOA group had 87.5% survival where PD-VI survival was 28.6%. No difference in survival was seen in the PI or AI groups. The PD-VI-REBOA group had total blood loss of 575.0 ± 339.1 mL, which was less than the PD-VI group (1,086.0 ± 532.1 mL). There was no difference in total thoracic blood loss in the PI and AI groups with the addition of REBOA. All groups showed an equivalent decrease in HCO3 and base excess and increase in lactate at the end of the 30-minute prehospital phase.

CONCLUSION

In this study, zone 1 REBOA improved survival and decreased blood loss with major VI, where no differences were seen in parenchymal and subclavian artery injuries. For thoracic bleeding without surgical capability, outcomes may be improved with REBOA, and these findings challenge current guidelines stating the contraindication of REBOA use in this setting.