Evaluation of activation characteristics of a canine platelet concentrate produced by a commercial double centrifugation system

Introduction

In veterinary medicine there are few readily available products for platelet transfusion to patients with thrombocytopenia. Commercial tabletop platelet concentrating systems have recently become available to veterinarians, primarily directed towards uses associated with regenerative medicine. These systems could potentially be used to produce fresh concentrated platelets for use in transfusion medicine. This study evaluated the concentration, activation, and sterility of a double centrifugation platelet concentrate (PC) produced by a commercial benchtop system.

Methods

Ten healthy dogs were studied. Whole blood was collected and mixed with ACD-A in a 1:7.6 ratio of ACD-A to whole blood. 12 mL of this mixture was processed into PC via single centrifugation, while 60 mL of the anticoagulated whole blood was processed via a commercial double centrifugation system. Both types of PC were evaluated for platelet concentration, CD62P expression with and without thrombin stimulation, and for sterility.

Results

Mean platelet count in the double centrifuged PC was 863 ± 352 × 103/μL, with very low white blood cell contamination (median of 0.47 × 103 leukocyte/μL (range 0.15-2.18 × 103/μL)). The double-centrifuged PC had similar baseline activation characteristics (as determined by P-selectin expression) as the single centrifuge PC (0.76% vs. 0.72% unstimulated, 30.5% vs. 34.9% stimulated, p = 0.432).

Discussion

The benchtop PC system studied here did not cause activation of platelets during production and produced a sterile product that can be further investigated as a source of fresh platelet concentrates for transfusion purposes.

Dose-dependent effect of canine lyophilized platelet on an in vitro hemodilution model

The transfusion of stored platelets has emerged as an efficient method for treating dogs with thrombocytopenia. However, the availability of fresh platelets is limited in veterinary medicine due to demanding storage conditions. Lyophilized platelets have long shelf lives and can be easily stored, increasing their accessibility for thrombocytopenic dogs. Due to the lack of research and information on the dose effect, canine lyophilized platelets are used at a clinical dosage without research-based evidence. This study was to evaluate the dose effect of lyophilized canine platelets on blood coagulability. Three different concentrations of lyophilized canine platelets were added to in vitro hemodilution blood model, increasing the platelet count by 25, 50, and 100 × 10⁶/ml and coagulation profiles were analyzed. The coagulability was evaluated via the plasma fibrinogen concentration, coagulation time, thromboelastography (TEG), and platelet function analyzer (PFA). Higher concentrations of lyophilized platelets showed dose-dependent association with decreased aPTT and R-time of TEG and increased alpha angle and MA of TEG. These results showed the potential that the higher dose of canine lyophilized platelets better improve blood coagulability than the standard dose and provided the basis for further safety and clinical studies.

Association of Veterinary Hematology and Transfusion Medicine (AVHTM) Transfusion Reaction Small Animal Consensus Statement (TRACS) Part 2: Prevention and monitoring

OBJECTIVE

To systematically review available evidence to develop guidelines for the prevention of transfusion reactions and monitoring of transfusion administration in dogs and cats.

DESIGN

Evidence evaluation of the literature (identified through Medline searches through Pubmed and Google Scholar searches) was carried out for identified transfusion reaction types in dogs and cats. Evidence was evaluated using PICO (Population, Intervention, Comparison, Outcome) questions generated for each reaction type. Evidence was categorized by level of evidence (LOE) and quality (Good, Fair, or Poor). Guidelines for prevention and monitoring were generated based on the synthesis of the evidence. Consensus on the final recommendations and a proposed transfusion administration monitoring form was achieved through Delphi-style surveys. Draft recommendations and the monitoring form were made available through veterinary specialty listservs and comments were incorporated.

RESULTS

Twenty-nine guidelines and a transfusion administration monitoring form were formulated from the evidence review with a high degree of consensus CONCLUSIONS: This systematic evidence evaluation process yielded recommended prevention and monitoring guidelines and a proposed transfusion administration form. However, significant knowledge gaps were identified, demonstrating the need for additional research in veterinary transfusion medicine.

Prophylactic administration of oral calcium carbonate during plateletpheresis: A bicentric prospective study

BACKGROUND:

Administration of anticoagulant citrate and dextrose (ACD-A) chelates ionized calcium in blood and causes hypocalcemia in plateletpheresis donors. The aim of the study was to observe the effects of oral calcium (Ca) supplementation during plateletpheresis on various parameters related to calcium metabolism.

MATERIALS AND METHODS:

This study was performed between January 2014 and December 2014 on 200 plateletpheresis donors. They were divided into two groups. In group A donors (n=100), no prophylactic oral calcium supplementation was given. In group B (n=100) donors, 2000 mg of calcium was given one hour before the start of the procedure, 500 mg was given at the start of the procedure and 500 mg calcium was given just before the end of procedure. Biochemical parameters like serum total calcium (T Ca), serum total magnesium (T Mg) and ionized calcium level (iCa) were measured before and after the procedure. Relative risk of citrate toxicity was measured between the two groups.

RESULTS:

There was a significant fall in total calcium (pre 9.02 mg/dl, post 8.23 mg/dl,), ionized calcium level (pre 1.14 mmol/L, post 0.91 mmol/L) and total magnesium (pre 1.92 mg/dl, post 1.79 mg/dl) amongst the donors who did not receive prophylactic calcium supplementation. Despite calcium intake, in prophylactic calcium intake group, we did observe a significant drop in total magnesium (pre 2.04 mg/dl, post 1.94 mg/dl) and ionized calcium level (pre 1.25 mmol/L, post 1.12 mmol/L, p<0.01). We did observe a drop in total calcium level, however, this observation was not statistically significant. The risk (RR=5.44) of citrate toxicity was higher among group A donors.

CONCLUSION:

Prophylactic oral calcium carbonate supplementation would help in to reduce the risk of citrate toxicity. Therefore, we suggest for prophylactic oral administration of 3000 mg elemental calcium carbonate in three divided doses to make PP procedures uneventful.

Clinical Application of Apheresis in Very Small Dogs Weighing <8 kg to Pediatric Patients

Apheresis in low body weight children and adolescents is challenging due to a variety of technical and clinical issues including vascular access, low total blood volume, and hypotension. Although dogs have been a valuable preclinical model for apheresis, the procedure can be challenging since many pure-bred dogs are extremely small. Therefore, apheresis in these very small breeds presents very similar challenges as seen when performing the procedure in very low body weight people. We describe apheresis of four very small dogs, weighing from 4.6 to 7.6 kg, using either a COBESpectra and Spectra Optia apheresis system (Terumo BCT, Lakewood, CO, USA). Two dogs underwent large volume leukapheresis to collect mononuclear cells in preparation for hematopoietic stem cell transplantation and two dogs underwent therapeutic plasma exchange to treat an immune-mediated disease. In all cases, a dual-lumen hemodialysis catheter placed in the jugular vein provided adequate machine inlet and return flow rates. Machine priming was necessary to maintain hemodynamic stability during the beginning of the procedure, and rinseback was avoided for the same reason. Anticoagulant citrate dextrose solution, solution A was used for the large volume leukapheresis procedures and a combination of anticoagulant citrate dextrose solution, solution A and heparin was used for the therapeutic plasma exchange procedures. As such, serum iCa levels were regularly monitored and 10% calcium gluconate constant rate infusions were used to prevent citrate toxicity. All dogs completed the aphereses with no life-threatening adverse events. We conclude that aphereses in very small dogs is feasible if close attention is paid to hemodynamic stability and citrate toxicity.

Platelet lysate obtained via plateletpheresis performed in standing and awake equine donors

BACKGROUND

Platelet preparations containing growth factors, attachment factors, and enzymes are appealing to enhance healing of injured tissues and as an alternative to xenogenic serum in cell culture media. Plateletpheresis is commonly used to collect platelets in human medicine but has not been validated in horses.

STUDY DESIGN AND METHODS

Plateletpheresis to collect platelet concentrate was performed on six female, mixed breed, chemically restrained horses using commercially available apheresis equipment. Before and immediately after plateletpheresis, we performed physical examinations and collected blood for chemistry and coagulation panels and then again at 8, 16, 24, and 48 hours after the procedure. To produce platelet lysate, the platelet concentrate underwent two freeze-thaw cycles followed by centrifugation and filtration processing. The platelet lysate was then analyzed for cellular debris, fibrinogen, and growth factors.

RESULTS

The collected platelet concentration contained a mean platelet yield of 390 × 10³ /μL. Donor platelet count decreased from a mean of 193 × 10³ /μL to 138 × 10³ /μL after plateletpheresis, but no individual was at risk for hemorrhage. Pooled platelet lysate had minimal cellular residue and contained growth factor concentrations at 6.1 ng/mL for transforming growth factor-β1, at 3.5 ng/mL for platelet-derived growth factor-BB, and at 13.8 ng/mL for vascular endothelial growth factor-A.

CONCLUSION

Plateletpheresis using commercially available apheresis equipment is a feasible option for collecting platelet concentrate from equine donors. The lysate generated from the apheresis product contains growth factors and has potential to be used as a fetal bovine serum substitute for cell culture.

Use of fresh platelet concentrate or lyophilized platelets in thrombocytopenic dogs with clinical signs of hemorrhage: a preliminary trial in 37 dogs

OBJECTIVE

To examine the safety and feasibility of using lyophilized platelets (LYO) and fresh platelet concentrate (FRESH) in bleeding thrombocytopenic dogs.

DESIGN

Preliminary prospective randomized clinical trial.

SETTING

Two private referral centers and 3 university teaching hospitals.

ANIMALS

Thirty-seven dogs with a complaint of hemorrhage associated with thrombocytopenia (platelet count <70 × 10(9) /L [70,000/μL], a hematocrit >15%, and that had received neither vincristine nor platelet-containing transfusions within 72 h of enrollment were studied.

INTERVENTIONS

Animals were randomized to receive LYO or FRESH, dosed according to weight. Physical examination, complete blood counts, and coagulation testing (prothrombin time and activated partial thromboplastin time) were performed at enrollment. Physical examinations were also performed immediately post transfusion, and at 1 and 24 h after transfusion. Complete blood counts were repeated immediately post transfusion and at 24 h. Collected data included bleeding score (BLS), response to transfusion, adverse reactions, hospitalization time, need for additional transfusions, survival to discharge, and 28-d survival.

MEASUREMENTS AND MAIN RESULTS

Twenty-two dogs received LYO and 15 received FRESH. There was no difference between groups in age, weight, BLS, platelet count, white blood cell count, hematocrit, or presence of melena. There was no difference between groups in transfusion reaction rates, the need for additional transfusions, 24-h BLS, hospitalization time, survival to discharge, or 28-d survival.

CONCLUSIONS

Transfusion of LYO was feasible and associated with a low transfusion reaction rate in this limited study of thrombocytopenic canine patients presenting with mild-to-severe hemorrhage. LYO were easy to use and provided storage advantages over FRESH. Further study of this product, including examination of efficacy and platelet life span, is warranted.

Collection of peripheral blood CD34+ progenitor cells from healthy dogs and dogs diagnosed with lymphoproliferative diseases using a Baxter-Fenwal CS-3000 Plus blood cell separator

BACKGROUND

Canine peripheral blood mononuclear cell (PBMC) apheresis using a Baxter-Fenwal CS-3000 Plus automated blood cell separator has not been reported.

OBJECTIVE

To determine the feasibility and safety of using a CS-3000 Plus blood cell separator with a small volume separation container holder (SVSCH) and small volume collection chamber (SVCC) to harvest canine PBMCs from dogs weighing <50 kg.

ANIMALS

Eight healthy mongrel dogs and 11 client-owned dogs in clinical remission for lymphoproliferative diseases (LPD).

METHODS

In this prospective study, aphereses were performed using a Baxter-Fenwal CS-3000 Plus blood cell separator, with or without recombinant human granulocyte colony-stimulating factor (rhG-CSF) treatment.

RESULTS

Aphereses from 6 healthy dogs given rhG-CSF yielded an average of 1.1 × 10(7) ± 8.2 × 10(6) CD34+ cells/kg. Aphereses from LPD dogs given rhG-CSF yielded an average of 5.4 × 10(6) ± 3.25 × 10(6) CD34+ cells/kg (P = .17). Higher hematocrit in both groups of dogs receiving rhG-CSF correlated with an increased number of CD34+ cells/kg harvested (healthy, P = .04; LPD, P = .05). Apheresis was well tolerated by all dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Canine PBMC apheresis using the Baxter-Fenwal CS-3000 Plus cell separator with an SVSCH and SVCC is a feasible and safe option for harvesting an adequate number of CD34+ peripheral blood progenitor cells from dogs weighing ≥17 kg for hematopoietic cell transplantation.

Effects of prostaglandin E1 on the preparation of platelet concentrates in dogs

BACKGROUND

Platelet concentrates (PC) are prepared by centrifugation of platelet-rich plasma (PRP) that is prepared by centrifugation of whole blood. The resuspension of the platelet pellet during PC preparation from dogs is difficult because of platelet activation induced by centrifugation.

OBJECTIVES

To investigate the efficacy of adding prostaglandin E(1) (PGE(1) ) to prevent platelet activation during PC preparation from dogs.

ANIMALS

Fifteen healthy Beagle dogs.

METHODS

Prospective, experimental trial: PGE(1) was added to PRP before the high-speed centrifugation during PC preparation. To estimate the effect of this addition, we assessed the platelet aggregability before transfusion, the survival of the platelets after transfusion, and the platelet reactivity after transfusion, which is estimated by the P-selectin expression of the platelets when stimulated by thrombin.

RESULTS

The difficulty associated with platelet resuspension was resolved by PGE(1.) PGE(1) strongly inhibited platelet aggregation induced by collagen and ADP; however, it recovered after the platelets were resuspended in plasma without PGE(1) (mean aggregation ratio; collagen: 10.00-80.80%, ADP: 8.20-53.60%). Survival of the platelets after transfusion was not affected by PGE(1) (mean 8.04 and 7.56 days, without and with PGE(1) ), and thrombin-induced P-selectin expression after transfusion in PGE(1) -treated PC was also well maintained (mean positive ratio 53.7 and 47.9%, before and 24 hours after transfusion).

CONCLUSIONS AND CLINICAL IMPORTANCE

The addition of PGE(1) in PRP before the centrifugation of PRP can improve the preparation efficiency of PC from dogs, while maintaining the therapeutic efficacy of the platelets.

Heart rate variability during and after peripheral blood stem cell leukapheresis in autologous transplant patients and allogeneic transplant donors

Side effects of varying severity are frequent in peripheral blood stem cell harvest (PBSCH). Life-threatening complications associated with PBSCH have also been reported. Heart rate variability (HRV), which reflects sympathovagal balance and autonomic cardiovascular control, has been a subject of intense interest in various diseases precipitating sudden death. Here, we prospectively assessed the impact of leukapheresis on HRV among autologous hematopoietic cell transplant patients and healthy donors. We found that HRV indicators, the standard deviation of normal-to-normal intervals (SDNN) value, the square root of the mean of the sum of squared differences between the adjacent normal-to-normal interval (r-MSSD) value, total frequency (TF), high frequency (HF) and low frequency (LF) powers decreased significantly to morbid levels during leukapheresis (all P < 0.01). Morbid changes in SDNN value, TF and LF powers were significantly sustained for 6-9 h after leukapheresis (all P < 0.05). Furthermore, TF and LF powers prior to leukapheresis were significantly lower in subjects with symptomatic hypotension than in the other subjects [3282 (3121-4427) vs. 6018 (4983-9816) ms(2), P = 0.03; 93 (42-144) vs. 237 (142-360) ms(2), P = 0.03, respectively]. Our results suggest that HRV analysis might be of use in evaluating and predicting the adverse effects of cardiovascular complications in PBSCH.

Effects of anticoagulant on pH, ionized calcium concentration, and agonist-induced platelet aggregation in canine platelet-rich plasma

OBJECTIVE-To compare effects of 3.8% sodium citrate and anticoagulant citrate dextrose solution National Institutes of Health formula A (ACD-A) on pH, extracellular ionized calcium (iCa) concentration, and platelet aggregation in canine platelet-rich plasma (PRP). SAMPLE POPULATION-Samples from 12 dogs. PROCEDURES-Blood samples were collected into 3.8% sodium citrate (dilution, 1:9) and ACD-A (dilution, 1:5). Platelet function, pH, and iCa concentration were evaluated in PRP. Platelet agonists were ADP, gamma-thrombin, and convulxin; final concentrations of each were 20microm, 100nM, and 20nM, respectively. Washed platelets were used to evaluate effects of varying the pH and iCa concentration. RESULTS-Mean pH and iCa concentration were significantly greater in 3.8% sodium citrate PRP than ACD-A PRP. Platelet aggregation induced by ADP and gamma-thrombin was markedly diminished in ACD-A PRP, compared with results for 3.8% sodium citrate PRP. Anticoagulant had no effect on amplitude of convulxin-induced platelet aggregation. In washed platelet suspensions (pH, 7.4), there were no differences in amplitude of platelet aggregation induced by convulxin or gamma-thrombin at various iCa concentrations. Varying the pH had no effect on amplitude of aggregation induced by convulxin or gamma-thrombin, but the aggregation rate increased with increasing pH for both agonists. CONCLUSIONS AND CLINICAL RELEVANCE-Aggregation of canine platelets induced by ADP and gamma-thrombin was negligible in ACD-A PRP, which suggested an increase in extraplatelet hydrogen ion concentration inhibits signaling triggered by these agonists but not by convulxin. Choice of anticoagulant may influence results of in vitro evaluation of platelet function, which can lead to erroneous conclusions.