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Topic:Platelets
Platelets are small, anucleated cell fragments derived from megakaryocytes in the bone marrow, playing a key role in hemostasis and thrombosis in horses. They contribute to the formation of blood clots by adhering to the site of vascular injury, aggregating with one another, and facilitating the coagulation process. In equine medicine, platelet count and function are important parameters in assessing bleeding disorders and thrombotic conditions. Variations in platelet count can indicate underlying health issues, such as inflammation, infection, or bone marrow disorders. This page compiles peer-reviewed research studies and scholarly articles that explore the physiology, pathology, and clinical implications of platelets in equine health.
Regenerative therapies for equine degenerative joint disease: a preliminary study. Degenerative joint disease (DJD) is a major cause of reduced athletic function and retirement in equine performers. For this reason, regenerative therapies for DJD have gained increasing interest. Platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) were isolated from a 6-year-old donor horse. MSCs were either used in their native state or after chondrogenic induction. In an initial study, 20 horses with naturally occurring DJD in the fetlock joint were divided in 4 groups and injected with the following: 1) PRP; 2) MSCs; 3) MSCs and PRP; or 4) chondrogenic induced MSCs and PRP. The ho...
Hemostatic profile during late pregnancy and early postpartum period in mares. Hemostasis is a physiological process that prevents excessive blood loss and represents a protective mechanism at the time of delivery. Peripartum hemorrhage is a recurring hazardous condition to mare's health; therefore, we aimed to study mares' hemostatic profile to investigate whether physiological adjustments occur during late pregnancy and early postpartum. Fifteen pregnant mares have been monitored from the 34th week of pregnancy until the third week after foaling. Fifteen nonpregnant mares were used as control group. Jugular blood samples were analyzed for platelet count (Plt), prothrom...
Hematologic and biochemical profiles in Standardbred mares during peripartum. The purposes of this study were to determine physiological changes occurring in hematologic and biochemical parameters in mares between the last month of gestation and the first week after parturition. If a significant change was observed with respect to the reference interval of an adult horse, a further aim of the study was to establish different reference intervals. Blood samples were collected from 62 healthy pregnant Standardbred mares. Seventeen nonpregnant and nonlactating mares were used as a control group. In pregnant mares, blood sampling was conducted every three days from 1 month b...
The effect of a gelatin β-tricalcium phosphate sponge loaded with mesenchymal stem cells (MSC), bone morphogenic protein-2, and platelet-rich plasma (PRP) on equine articular cartilage defect. We evaluated the curative efficacy of a gelatin β-tricalcium phosphate (β-TCP) sponge loaded with mesenchymal stem cells (MSC), bone morphogenic protein-2 (BMP-2), and platelet-rich plasma (PRP) by insertion into an experimentally induced osteochondral defect. A hole of 10 mm diameter and depth was drilled in the bilateral medial femoral condyles of 7 thoroughbred horses, and into each either a loaded sponge (treatment) or a saline-infused β-TCP sponge (control) was inserted. After 16 weeks, defects were examined by computed tomography, macroscopic analyses, and histological analyses. The m...
Identification and characterization of platelet α2-adrenoceptors and imidazoline receptors in rats, rabbits, cats, dogs, cattle, and horses. This study aimed to pharmacologically identify and characterize α2-adrenoceptors and imidazoline (I) receptors (I1- and I2-subtype) on canine, feline, bovine, equine, murine, and leporine platelet membranes. Saturation binding studies with both (3)H-yohimbine and (3)H-clonidine showed that α2-adrenoceptors were expressed on canine, leporine, feline, and murine platelets but not on bovine and equine platelets. In competition studies, the rank order of affinity of 6 compounds for canine platelet α2-adrenoceptors was similar to that of potency at α2A-subtype reported in human platelets. Satur...
Identification of potential platelet alloantigens in the Equidae family by comparison of gene sequences encoding major platelet membrane glycoproteins. Platelet alloantigens in horses may play an important role in the development of neonatal alloimmune thrombocytopenia (NAIT). Objective: The objective of this study was to evaluate genes encoding major platelet glycoproteins within the Equidae family in an effort to identify potential alloantigens. Methods: DNA was isolated from blood samples obtained from Equidae family members, including a Holsteiner-Oldenburg cross, a Quarter horse, a donkey, and a Plains zebra (Equus burchelli). Gene sequences encoding equine platelet membrane glycoproteins IIb, IIIa (integrin subunits αIIb and β3), Ia (...
Bioengineered osteochondral precursor for treatment of osteochondritis dissecans in a Thoroughbred filly. A 13-month-old Thoroughbred filly was diagnosed with osteochondritis dissecans (OCD) of the medial tibial malleolus. A sponge impregnated with platelet-rich plasma, bone morphogenetic protein-2, mesenchymal stem cells and gelatin β-tricalcium phosphate was applied to the OCD site following arthroscopy and debridement. Postoperative radiography (every week for 16 weeks), computed tomography (CT) (16 weeks postoperatively), arthroscopy (16 weeks postoperatively) and biopsy of the regenerated tissue (16 weeks postoperatively) were performed to evaluate the outcome. Radiographically, the defect b...
Allogeneic adipose tissue-derived mesenchymal stem cells in combination with platelet rich plasma are safe and effective in the therapy of superficial digital flexor tendonitis in the horse. Overstrain tendonitis are common pathologies in the sport horses. Therapeutic approaches to tendon healing do not always result in a satisfactory anatomical and functional repair, and healed tendon is often characterized by functional impairment and high risk of reinjury. Recently, mesenchymal stem cells (MSCs) and platelet rich plasma (PRP) have been proposed as novel therapeutic treatments to improve the tendon repair process. MSCs are multipotent, easy to culture and being originated from adult donors do not pose ethical issues. To date, autologous MSCs have been investigated mainly in the ...
Effects of intravenous administration of polymyxin B in neonatal foals with experimental endotoxemia. To evaluate the effect of IV administration of polymyxin B on clinical and serum biochemical variables in foals with experimental endotoxemia. Methods: Prospective experimental study. Methods: 14 healthy neonatal foals. Methods: Foals were randomly assigned to a treatment or control group and were administered a single dose of lipopolysaccharide (0.5 μg/kg [0.23 μg/lb]) IV over 30 minutes. The treatment group received polymyxin B (6,000 U/kg [2,727 U/lb], IV) immediately after completion of lipopolysaccharide infusion; the control group was administered an equal volume of saline (0.9% NaCl) ...
Synovial fluid growth factor and cytokine concentrations after intra-articular injection of a platelet-rich product in horses. Platelet-rich plasma (PRP) products may be useful for treatment of joint disease in horses, but may contain undesirable pro-inflammatory cytokines in addition to growth factors. This study investigated whether autologous PRP increases synovial fluid growth factor and cytokine concentrations when injected into normal equine metacarpophalangeal and metatarsophalangeal (fetlock) joints. Fetlock joints of seven healthy horses received one of four treatments: saline, resting PRP, CaCl2-activated PRP or thrombin-activated PRP. Synovial fluid was sampled prior to injection and at 6, 24, 48 and 96 h p...
Effects of clopidogrel on the platelet activation response in horses. To evaluate the platelet activation response before and after treatment with clopidogrel in horses. Methods: 12 healthy adult mares. Methods: In a masked study, horses (6/group) were randomly allocated to alternately receive placebo or clopidogrel via nasogastric tube at a loading dose of 4 mg/kg followed by 2 mg/kg every 24 hours. Blood samples were collected before and 72 hours after initiation of treatment for ADP- and collagen-induced light transmission aggregometry; determination of closure time in collagen-ADP cartridges; modified thrombelastography for comparison of maximal amplitudes g...
Changes in blood coagulation induced by exercise training in young athletic horses. Prothrombin Time (PT), Activated Partial Prothrombin Time (APTT), Fibrinogen concentration (Fbg) and Platelet number (Plt) were evaluated in 20 young athletic horses during a training program. A standardized exercise test (SET) was performed every month for three months. The V4 variations (the speed, in m/min, reached at the blood lactate concentration of 4 mmol/l) obtained for each test were calculated to assess the effect of training program on athletic performance. Blood samples were collected at 20-day intervals over a period of 80 days from the beginning of the training program. The V4 (P...
Equine tendonitis therapy using mesenchymal stem cells and platelet concentrates: a randomized controlled trial. Tendon injury is a major cause of lameness and decreased performance in athletic equines. Various therapies for tendonitis have been described; however, none of these therapies results in complete tissue regeneration, and the injury recurrence rate is high even after long recovery periods involving rest and physiotherapy. Methods: A lesion was induced with collagenase gel in the superficial digital flexor tendon in the center portion of the metacarpal region of eight equines of mixed breed. After two weeks, the lesions of the animals in the treated and control groups were treated through the i...
Injection of platelet- and leukocyte-rich plasma at the junction of the proximal sesamoid bone and the suspensory ligament branch for treatment of yearling Thoroughbreds with proximal sesamoid bone inflammation and associated suspensory ligament branch desmitis. To determine the effects of treatment with platelet- and leukocyte-rich plasma (PRP) on future 2-, 3-, and 4-year-old racing performance of yearling Thoroughbreds with proximal sesamoid bone inflammation and associated suspensory ligament branch (SLB) desmitis. Methods: Randomized clinical trial. Methods: 39 yearling Thoroughbreds. Methods: Yearling Thoroughbreds with radiographic evidence of performance-limiting proximal sesamoid bone inflammation and ultrasonographic evidence of associated SLB desmitis were identified and randomly assigned to undergo PRP (treatment group) or saline (0.9% NaC...
Simple tube centrifugation for processing platelet-rich plasma in the horse. This study evaluated the quality and bacteriologic safety of platelet-rich plasma (PRP) produced by 3 simple, inexpensive tube centrifugation methods and a commercial system. Citrated equine blood collected from 26 normal horses was processed by 4 methods: blood collection tubes centrifuged at 1200 and 2000 × g, 50-mL conical tube, and a commercial system. White blood cell (WBC), red blood cell (RBC), and platelet counts and mean platelet volume (MPV) were determined for whole blood and PRP, and aerobic and anaerobic cultures were performed. Mean platelet concentrations ranged from 1.55- to 2...
Performance of a gravitational marrow separator, multidirectional bone marrow aspiration needle, and repeated bone marrow collections on the production of concentrated bone marrow and separation of mesenchymal stem cells in horses. Objective-To determine the efficiency of a novel point-of-care gravitational marrow separator and bone marrow aspiration needle for concentrated bone marrow production and bone marrow-derived mesenchymal stem cell (MSC) separation and assess the effect of repeated bone marrow collections in horses. Animals-8 healthy adult horses. Procedures-Bone marrow aspiration was performed twice (1 month apart) from sternebral bodies with a standard or prototype multidirectional needle. Concentrated bone marrow was obtained by gravitational marrow separation and evaluated for WBC and platelet counts, autom...
In vitro effects of three formulations of hydroxyethyl starch solutions on coagulation and platelet function in horses. To investigate the in vitro effects of 3 hydroxyethyl starch (HES) solutions on viscoelastic coagulation testing and platelet function in horses. Methods: Blood samples collected from 7 healthy adult horses. Methods: Blood samples were diluted with various crystalloid and HES solutions to approximate the dilution of blood in vivo that occurs with administration of a 10 and 20 mL/kg fluid bolus to a horse (1:8 and 1:4 dilutions, respectively). Diluted samples were analyzed through optical platelet aggregometry, platelet function analysis, thromboelastography, and dynamic viscoelastic coagulomet...
Intra-articular use of a platelet-rich product in normal horses: clinical signs and cytologic responses. (1) To report the clinical and synovial effects of a platelet-rich product (PRPr) in normal equine joints, (2) to assess the persistence of platelets within synovial fluid after intra-articular injection, (3) to compare responses to different preparations of that product, and (4) to evaluate a gravity filtration system for PRPr preparation in horses. Methods: Experimental. Methods: A platelet-rich saline product (PRPr) was prepared from 7 normal horses using a proprietary preparation device and was divided into 3 treatments: resting, CaCl2 -activated (23 mM, final), and bovine thrombin-activ...
Pharmacodynamics of multi-dose low molecular weight heparin in healthy horses. To compare the pharmacodynamics of once daily and twice daily administration of low molecular weight heparin (LMWH) administration in horses. Methods: Randomized cross over study. Methods: Adult mixed breed healthy mares (n = 6). Methods: LMWH (dalteparin) was administered (50 U/kg subcutaneously) either every 12 or 24 hours for 3 consecutive days. Anti-factor Xa activity was measured before and at select time points after LMWH administration. Packed cell volume (PCV), platelet count, partial thromboplastin time (PTT), and anti-thrombin (AT) activity were monitored throughout the study. Result...
Effects of imidazoline and nonimidazoline alpha-adrenergic agents, including xylazine, medetomidine, yohimbine, tolazoline, and atipamezole, on aggregation of bovine and equine platelets. To investigate effects of various imidazoline and nonimidazoline α-adrenergic agents on aggregation and antiaggregation of bovine and equine platelets. Methods: Blood samples obtained from 8 healthy adult cattle and 16 healthy adult Thoroughbreds. Methods: Aggregation and antiaggregation effects of various imidazoline and nonimidazoline α-adrenergic agents on bovine and equine platelets were determined via a turbidimetric method. Collagen and ADP were used to initiate aggregation. Results: Adrenaline, noradrenaline, or α-adrenoceptor agents alone did not induce changes in aggregation of bov...
Effects of the breed, sex and age on cellular content and growth factor release from equine pure-platelet rich plasma and pure-platelet rich gel. There is no information on the effects of the breed, gender and age on the cellular content and growth factor (GF) release from equine pure-platelet rich plasma (P-PRP) and pure-platelet rich gel (P-PRG). The objectives of this study were: 1) to compare the cellular composition of P-PRP with whole blood and platelet poor plasma (PPP); 2) to compare the concentration of transforming GF beta 1 (TGF-β1) and platelet derived GF isoform BB (PDGF-BB) between P-PRP treated with non-ionic detergent (P-PRP+NID), P-PRG (activated with calcium gluconate -CG-), PPP+NID, PPP gel (PPG), and plasma and; 3) ...
Equine platelets inhibit E. coli growth and can be activated by bacterial lipopolysaccharide and lipoteichoic acid although superoxide anion production does not occur and platelet activation is not associated with enhanced production by neutrophils. Activated platelets can contribute to host defense through release of products with bactericidal actions such as antimicrobial peptides and reactive oxygen species (ROS), as well as by forming heterotypic aggregates with neutrophils and enhancing their antimicrobial properties. Whilst release of vasoactive mediators from equine platelets in response to stimuli including bacterial lipopolysaccharide (LPS) has been documented, neither ROS production, nor the effects of activated platelets on equine neutrophil ROS production, have been reported. This study first sought evidence that activated equ...
Optimization of leukocyte concentration in platelet-rich plasma for the treatment of tendinopathy. Numerous methods are available for platelet-rich plasma (PRP) generation, but evidence defining the optimum composition is lacking. We hypothesized that leukocyte-reduced PRP would result in lower inflammatory cytokine expression compared with concentrated-leukocyte PRP and that maintaining the platelet:white blood cell (WBC) ratio would compensate for the effect of increased WBC concentration. Methods: Blood and flexor digitorum superficialis tendons were collected from young adult horses. Three PRP groups were generated with the same platelet concentration but different WBC concentrations: i...
ADP-induced platelet aggregation after addition of tramadol in vitro in fed and fasted horses plasma. Adenosine diphosphate (ADP)-induced platelet aggregation in fed and fasted horses after addition of tramadol hydrochloride was evaluated in vitro. On 10 horses citrated blood samples were collected 2h after feeding (fed animals) and 21 h after feeding (fasted animals). Final concentrations of ADP 1 and 0.5 μM, and tramadol hydrochloride (1, 15, 30, 45 and 60 min after the addition of tramadol) were used to determine the maximum degree and initial velocity of platelet aggregation. Repeated measures multifactor analysis of variance (MANOVA) was used to evaluate the effect of feeding/fasting con...
Assessment of acute moderate hyperglycemia on traditional and thromboelastometry coagulation parameters in healthy adult horses. To determine whether experimentally induced acute moderate hyperglycemia is associated with coagulation activation in healthy adult horses. Methods: Prospective experimental study. Methods: University veterinary teaching hospital. Methods: Six healthy adult horses. Methods: Hyperglycemia (10.0-13.3 mmol/L [180-240 mg/dL]) was induced and maintained for 6 hours using a hyperglycemic clamp technique. Blood glucose concentrations were assessed using a point of care (POC) glucometer at 10- and 20-minute intervals throughout the hyperglycemic clamp procedure. Platelet count, fibrinogen concentratio...
Autologous point-of-care cellular therapies variably induce equine mesenchymal stem cell migration, proliferation and cytokine expression. Autologous cellular therapy products including adipose-derived stromal vascular fraction (SVF), bone marrow mononuclear cells (BMMNs), cord blood mononuclear cells (CBMNs) and platelet rich plasma are options for treatment of acute orthopaedic lesions while mesenchymal stem cells (MSCs) are culture expanded. These products may contribute to healing by secreting matrix proteins or growth factors, but they may also act on endogenous MSCs to facilitate healing. Objective: To determine the effects of cell therapy products on MSCs function in vitro. The hypothesis was that cell therapy products pro...
Effects of Platelet-Rich Plasma Composition on Anabolic and Catabolic Activities in Equine Cartilage and Meniscal Explants. To evaluate the effects of single- and double-spin preparations of platelet-rich plasma (PRP) on anabolic and catabolic activities of cartilage and meniscal explants in vitro. Methods: Single- and double-spin PRP was prepared using laboratory processing or commercial kits. The cellular contents were quantified, and each PRP was mixed in equal quantities with cell culture medium and added to cartilage or meniscus explant cultures, with or without interleukin 1 β (IL-1β). Extracellular matrix synthesis was quantified over 24 hours via (35)S-sulfate and (3)H-proline incorporation, while gene ex...
Activation of equine platelet-rich plasma: comparison of methods and characterization of equine autologous thrombin. To investigate and compare clinically relevant Platelet-rich plasma (PRP) activation methods. Methods: Experimental. Methods: PRP was prepared from 6 equine subjects. Activation of the PRP was performed by 4 methods (autologous thrombin, bovine thrombin, calcium chloride (CaCl(2) ), or freeze-thaw). The resultant PDGF-BB (where PDGF is platelet-derived growth factor) and TGFβ1 (where TGFβ is transforming growth factor beta) levels in PRP releasates were quantified by Enzyme-linked immunosorbent assay (ELISA) and compared. Growth factor contents were also compared between platelet-rich clots ...
Treatment with aspirin or clopidogrel does not affect equine platelet expression of P selectin or platelet-neutrophil aggregates. Inflammation-induced P-selectin (CD62P) expression on platelets and endothelial cells facilitates interactions among platelets and polymorphonuclear leukocytes (PMN), and can also promote coagulation. The effects of clopidogrel and aspirin (ASA) on equine platelet CD62P expression were investigated. Six horses were treated in a cross-over design with clopidogrel (2mg/kg PO q 24) or ASA (5mg/kg PO q 24h) for 5 days. Platelets collected at 24, 72, 96, 120, and 168 h after the initiation of therapy were stimulated using 0.1 μg/mL thrombin, followed by flow cytometric analysis using anti-CD41/61 ...
Scanning electron microscopy and microbiological evaluation of equine burn wound repair after platelet-rich plasma gel treatment. Deep second-degree burns (DSDb) involve all epidermis layers, including the basal laminae. In general, DSDb heals with extensive areas of scarring. Platelet-rich plasma (PRP) is a source of growth factors, obtained by centrifugation and addition of thrombin and calcium, resulting in a gel. The objective of this study was to monitor the healing of DSDb by sequential biopsies after PRP treatment and evaluating by a scanning electron microscopy. Also, characterize bacterial profile and PRP antibacterial effect in horses' burns. Four horses were placed into two groups, G1 and G2, with the groups r...
