Ex Vivo Manufacture of Megakaryocytes and Platelets from Stem Cells: Recent Advances Toward Transfusion in Humans.

The generation of ex vivo functional megakaryocytes (MK) and platelets is an important issue in transfusion medicine as donor dependence implies in limitations, such as shortage of eligible volunteers. Indeed, platelet transfusion is still a procedure that saves the lives of patients with defective platelet production. Recent technological development has enabled the isolation and expansion of stem cells that can be used as a source for the production of functional platelets for transfusion. In this review, we discuss recent approaches of in vitro or ex vivo production of MK and platelets, suggesting that, in the near future, donor-independent sources may become a possibility. The feasibility of using these cells in the clinic may be safer, and in vitro manipulation could generate universally compatible products, solving problems related to platelet refractoriness. However, functionality and survival testing of these products in human beings are scarce; therefore, additional studies are needed to consolidate this purpose.

Thrombocytopenia and the effect of platelet transfusions on the occurrence of intracranial hemorrhage in patients with acute leukemia - a nested case-control study.

We designed a study to describe the incidence of intracranial hemorrhage according to severity and duration of thrombocytopenia and to quantify the associations of platelet transfusions with intracranial hemorrhage in patients with acute leukemia. In this case-control study nested in a cohort of 859 leukemia patients, cases (n = 17) were patients diagnosed with intracranial hemorrhage who were matched with control patients (n = 55). We documented platelet counts and transfusions for seven days before the intracranial hemorrhage in cases and in a "matched" week for control patients. Three measures of platelet count exposure were assessed in four potentially important time periods before hemorrhage. Among these leukemia patients, we observed the cumulative incidence of intracranial hemorrhage of 3.5%. Low platelet counts were, especially in the three to seven days preceding intracranial hemorrhage, associated with the incidence of intracranial hemorrhage, although with wide confidence intervals. Platelet transfusions during the week preceding the hemorrhage were associated with higher incidences of intracranial hemorrhage; rate ratios (95% confidence interval) for one or two platelet transfusions and for more than two transfusions compared with none were 4.04 (0.73 to 22.27) and 8.91 (1.53 to 51.73) respectively. Thus, among acute leukemia patients, the risk of intracranial hemorrhage was higher among patients with low platelet counts and after receiving more platelet transfusions. Especially, the latter is likely due to clinical factors leading to increased transfusion needs.

Frozen Platelets-Development and Future Directions.

Storage requirements and outdating of platelets represent a continued challenge for blood banks. These hurdles are confounded for rural area hospitals or in military deployments. Over 60 years of research and development into frozen platelets have generated a stable and reproducible product. Valeri's method to freeze platelets in 6% dimethyl sulfoxide (DMSO) and storage at -80°C allows for long-term storage alleviating burdens placed on blood banks. Clinical studies show that frozen platelet transfusions are safe with no related thrombotic or other serious adverse events. There are ongoing efforts to demonstrate cryopreserved platelet (CPP) superiority in efficacy studies designed in trauma or cardiac surgery patients. Technical advances in CPP manufacturing including closed system manufacturing, applications of pathogen reduction technology and potency standard characterization add to the appeal of CPP as an alternative to traditional liquid-stored platelets (LP) in settings of supply shortages, mass casualty, active bleeding, rapid provision of HLA-compatible platelets, and remote care.

Evolution of perioperative blood transfusion practice after coronary artery bypass grafting in the past two decades.

BACKGROUND AND AIM OF THE STUDY: Transfusion of blood products after coronary artery bypass grafting (CABG) is associated with increased morbidity and mortality. We evaluated the perioperative use of blood products in patients undergoing CABG in our institution over the past two decades. METHODS: The study included 18 992 patients who underwent isolated CABG at our hospital between 1998 and 2017. Baseline characteristics of patients and the number of perioperative transfusions during their hospital stay (including red blood cells [RBCs], platelets, and fresh frozen plasma [FFP]) were assessed. Logistic regression models were used to identify risk factors for perioperative transfusion. RESULTS: The rates of perioperative RBC transfusion decreased for all patients undergoing isolated CABG (52.1% in 1998 vs 18.6% in 2017) in our institution. The mean number of transfused RBC units was significantly higher in women than in men (1.57 ± 2.2 vs 0.68 ± 1.84; P < .005); this difference remained significant over the years. After adjusting the results for other risk factors, female sex was a significant independent risk factor for perioperative RBC transfusion. The platelet transfusion rate increased over the past two decades (1.4% in 1998 vs 9.7% in 2017). The number of FFP transfusions remained unchanged. CONCLUSIONS: Over the past two decades, we observed a decrease in the incidence of perioperative RBC transfusions in patients undergoing isolated CABG, whereas platelet transfusions increased. Female sex was an independent predictor of perioperative RBC transfusion.

Trends in transfusion practice over 20 years in paediatric liver transplant programme.

BACKGROUND: We investigated changes to transfusion practices over time in paediatric liver transplant centre and evaluated the effect of transfusion practice to mortality. METHODS: A pilot retrospective study included two cohorts each with 101 sequential paediatric LT recipients: an Early group (1994-1998) and a Recent group (2009-2013). Demographic characteristics and data on the intraoperative transfusion of red blood cells (RBC), fresh-frozen plasma (FFP), platelets and cryoprecipitate were collected. Postoperative laboratory results were also obtained, together with donor and data regarding 1- and 5-year survival. Appropriate intergroup comparisons, univariate and multivariate analysis were made and P ≤ 0·05 was considered statistically significant. RESULTS: There were no significant group differences in demographic data (except patient height). Despite the fact that median total blood loss did not differ between groups (111 ml/kg in both groups), the Early group had greater levels of intraoperative RBC transfusion (75 vs. 59 ml/kg, respectively, P = 0·04) and less use of FFP (53 vs. 62 ml/kg, respectively, P = 0·01). Overall we noted a lower 1- and 5-year survival in the Early group (88·2% vs. 96%, P = 0·04 and 82·4% vs. 89·1%, P = 0·01, respectively). Univariate, but not multivariate regression analyses demonstrated that higher PELD score, RBC and FFP transfusion, and inclusion in the Early group were contributing factors to 1-year higher mortality. CONCLUSIONS: This retrospective analysis of blood loss and replacement in paediatric LT patients demonstrates that the majority of our patients suffer major haemorrhage and require large-volume RBC and FFP replacements. In our pilot study, large volume of RBC and FFP replacement did not contribute to mortality. Paediatric LT involves a number of multidisciplinary teams. Thus, all care-related factors and combinations thereof that may contribute to outcome and should be evaluated in the future.

Variation in Platelet Transfusion Practices in Cardiac Surgery.

OBJECTIVE: Although the morbidity associated with red blood cell transfusion in cardiac surgery has been well described, the impacts of platelet transfusion are less clearly understood. Given the conflicting results of prior studies, we sought to investigate the impact of platelet transfusion on outcomes after cardiac surgery across institutions in Maryland. METHODS: Using a multiinstitutional statewide database created by the Maryland Cardiac Surgery Quality Initiative, we retrospectively analyzed data from 10,478 patients undergoing isolated coronary artery bypass across 10 centers. Platelet transfusion practices were compared between institutions. Multivariate logistic regression model was used to analyze the association between platelet transfusion and 30-day mortality and postoperative complications. RESULTS: Rates of platelet transfusion varied between institutions from 4.4% to 24.7% ( P < 0.001), a difference that remained statistically significant in propensity score-matched cohorts. Among patients on preoperative antiplatelet therapy, transfusion rates varied from 8.5% to 46.4% ( P < 0.001). There was no statistically significant relationship between case volume and transfusion rates ( P = 0.815). In multivariate logistic regression, platelet transfusion was associated with increased risk of 30-day mortality (OR 2.43, P = 0.008), postoperative pneumonia (OR 2.21, P = 0.004), prolonged intubation (OR 2.05, P < 0.001), and readmission (OR 1.43, P = 0.039). CONCLUSIONS: Significant variation existed in platelet transfusion rates between institutions, even after controlling for various risk factors. This variation may be associated with increased mortality and length of stay. Further study is warranted to better understand risks associated with platelet transfusion. Standardizing practice may help reduce risk and conserve resources.

Hemorrhagic Complications of External Ventriculostomy in the Aspirin and P2Y12 Response Assay Era.

OBJECTIVE: Hemorrhagic complications reported from external ventricular drain (EVD) placement range from 10% to 44%. There remains limited literature investigating the incidence, risk factors, and mechanisms to prevent its occurrence, especially in the setting of antiplatelet agent use. We investigated EVD-related hemorrhagic complications after the implementation of VerifyNow platelet inhibition assays at our institution. METHODS: Medical records from 445 patients requiring EVD placement during a 2-year period during which our institution used the assays were reviewed. In total 345 patients were included, and 208 of them underwent assay testing. Indications for EVD included complications of cerebrovascular disease (n = 215), traumatic brain injury (n = 74), primary hydrocephalus (n = 23), and tumor (n = 33). Hemorrhage was defined as any new area of hyperdensity adjacent to or immediately along the catheter trajectory on computed tomography. RESULTS: There was no significant decrease in catheter-induced hemorrhage (CIH) between patients who underwent the VerifyNow assay and those who did not. Platelet transfusion did not significantly decrease the risk of CIH. CIH occurred in 17.7% of patients, significantly decreased when compared with our previously published incidence of 33% before platelet inhibition assay use (P < 0.05). Patients with cerebrovascular disease complications exhibited a significant decrease in CIH, 20% versus 39%, before assay use (P < 0.01). CONCLUSIONS: The incidence of hemorrhage is lower in our new cohort when compared with that of our previously published cohort. Despite the overall decreased rate of hemorrhage, there was no significant difference in hemorrhage rates between patients who did or did not undergo the assay. Platelet transfusion did not decrease the incidence of hemorrhage in patients with inhibited platelet function.

Long-term audit of platelet consumption in a university hospital.

OBJECTIVES: To determine the long-term trend in platelet consumption in a university hospital. MATERIALS AND METHODS: The annual consumption of platelets concentrate (PC) was analyzed over 23 years (1985-2007) in King Khalid University Hospital (KKUH), Riyadh, Saudi Arabia. RESULTS: The total 23 years consumption was 100,466 units of PC. Consumption went through 3 phases: the first, 1985-1994: the annual consumption increased from 1706 to 5912 which coincided with the increase in the number of patient admissions; the second, 1994-2003:featured a remarkable drop (48.9%) in annual consumption while patient admission remained stable. There was a concurrent decline in platelet consumption and all-cause mortality/patient. Third phase: 2003-2007, the consumption increased to reach 5642 units/year in 2007. The Department of Medicine consumed (52%), followed by Pediatrics (21%), and General Surgery (16%). CONCLUSION: This audit uncovered evidence of inappropriate platelet consumption that reached 48.9% in the period 1994 to 2003, which coincided with widely publicized HIV scare that dominated blood transfusion during that period. We also found evidence suggesting that reducing platelet transfusion could improve patient outcome.

Red cell and platelet transfusions in neonates: a population-based study.

OBJECTIVES: This study aimed to describe the use of red cells, platelets and exchange transfusions among all neonates in a population cohort, to examine trends in transfusion over time and to determine transfusion rates in at-risk neonates. DESIGN: Linked population-based birth and hospital data from New South Wales (NSW), Australia, were used to determine rates of blood product transfusion in the first 28 days of life. The study included all live births ≥23 weeks' gestation in NSW between 2001 and 2011. RESULTS: Between 2001 and 2011, 5326 of 989 491 live born neonates received a red cell, platelet or exchange transfusion (5.4/1000 births). Transfusion rates were 4.8 per 1000 for red cells, 1.3 per 1000 for platelets and 0.3 per 1000 for exchange transfusion. Overall transfusion rate remained constant from 2001 to 2011 (p=0.27). Among transfused neonates, 60% were <32 weeks' gestation (n=3210, 331/1000 births), 40% were ≥32 weeks' gestation (n= 2116, 2/1000 births) and 7% received transfusions in a hospital without a neonatal intensive care unit (NICU). Factors other than prematurity associated with higher transfusion rates were prior in utero transfusion (631/1000), congenital anomaly requiring surgery (440/1000) and haemolytic disorder (106/1000). CONCLUSIONS: In this population-based study, preterm neonates had a higher rate of transfusion than term neonates; however, 40% of those who received a transfusion were born ≥32 weeks' gestation and 7% were transfused in hospitals without an NICU. These findings need to be considered by transfusion services and personnel developing neonatal transfusion guidelines.

Risk of bleeding and use of platelet transfusions in patients with hematologic malignancies: recurrent event analysis.

A recent randomized trial (TOPPS) compared prophylactic platelet transfusions (for counts <10×10(9)/L) with a strategy of no-prophylaxis in adults with hematologic malignancies. Seventy percent of enrolled patients received an autologous hematopoietic stem cell transplant. Statistical models were developed to explore which patient factors or clinical characteristics are important prognostic factors for bleeding. These models were presented for baseline characteristics and for recurrent analysis of bleeding to assess the risks of World Health Organization grade 2-4 bleeding on any given day. Additional analyses explored the importance of fever. Treatment plan (chemotherapy/allogeneic hematopoietic stem cell transplant), female sex, and treatment arm (no-prophylaxis) were significantly associated with an increased number of days of bleeding. The number of days with a platelet count <10×109/L was significantly associated with a grade 2-4 bleed (P<0.0001). Patients with a temperature of at least 38°C had the highest hazard of a grade 2-4 bleed (hazard ratio: 1.7, 95% confidence interval: 1.3 to 2.4, compared with the risk in patients with a temperature <37.5°C). There was no evidence that minor bleeding predicted a grade 2-4 bleed. The results highlighted the limited role of correction of thrombocytopenia by platelet transfusion in reducing the risk of bleeding. Clinically stable patients undergoing autologous hematopoietic stem cell transplantation had the lowest risk of bleeding and benefited least from prophylactic platelet transfusions. Prospective studies are required to address the usefulness of risk factors to support better targeted platelet transfusions. TOPPS Controlled-Trials.com number ISRCTN08758735.

Scotblood 2012: transfusion/transplant medicine in the 2nd decade of the 21st century.

Transfusion medicine is a technology-based discipline, undergoing continual changes for improvement. It requires staff at all levels to be continually educated and trained in appropriate multidisciplinary skills, in line with the rapid developments in all areas of transfusion practice: from blood/organ collection, through processing and storage to the more advanced cellular and hospital-based transfusion/transplantation therapies. Whilst the majority of the challenges to improve hospital and general transfusion practice can be overcome through team work, education, timely objectives and perseverance, it is important to envisage opportunities for implementing digital technologies to reduce all of the applicable hazards associated with transfusion. These can vary widely from new and emerging pathogens to limitations of supply due to growing demographic changes in populations. In the first decade of 21st century we have already witnessed unprecedented advances in haematopoietic stem cell transplantation to minimise the toxicities of graft versus host disease (GvHD), and in cell therapy to explore immunotherapy against cancer and other malignant disorders. Today there are 1000 genome project hapmaps that only the extreme cost of their implementation to routine practices may limit. Transfusion medicine, like all disciplines of medicine, nevertheless, will face difficult choices between increasing healthcare technology and increasing worldwide health. Drs. Colligan and McGowan, the new lead organisers of this wonderful yearly educational programme have agreed to follow the previous organisers' strategy to make a summary report of their meeting to become available, through TRASCI to broader interested groups, with the sprit that "sharing is caring". The main highlights of the 2012 conference were: targeting transfusion practices in hospital, a continuing journey; emerging infections and the potential causes and possible remedial actions; building for the future; the challenging issues of donor recruitment/retention; and finally; the application of Information Technology as a decision making tool, utilising clinical audit monitoring to evaluate good practice. This year's conference also coincided with the retirement of Martin Bruce OBE, after his 41years distinguished career, who gave the most delightful and humorous talk of a" life time of learning" which delighted all the participants. Finally, 2012 also marked the retirements of the previous lead Scotblood organisers Prof. Robin Fraser and Dr. Hagop Bessos after over thirty years service to SNBTS, and to whom we would like to dedicate this meeting report and wish them a happy and healthy retirement. This commentary comprises summaries of the presentations, based in part on the abstracts provided by the speakers.

Emerging haemostatic agents and patient blood management.

The transfusion of allogeneic blood products has been considered as a life-saving procedure for patients suffering from major traumatic injury and those who are undergoing major surgery. The safety of blood products has improved in terms of infectious complications over the last three decades due to advanced donor screening procedures and tests. Nevertheless, non-infectious complications including a blood-type mismatch, volume overload and immunologic and non-immunologic reactions to blood products can adversely affect clinical outcomes. It is thus important to implement a patient-specific strategy in diagnosing bleeding cause(s) and optimising haemostatic therapy. This strategy is an integral part of patient blood management applicable to many perioperative patients. Recent advances in the haemostatic management and transfusion include better understanding of the pathomechanisms of coagulopathy, availability of point-of-care coagulation monitoring and introductions of pathogen-inactivated plasma and factor concentrates as well as recombinant coagulation factors. Understanding the indications and limitations of conventional haemostatic therapy, and potential indications and complications relating to emerging haemostatic agents, is important for perioperative physicians. In this article, we discuss current issues related to allogeneic plasma products and emerging biological haemostatic agents and techniques. Further, we review the mechanisms of action and available preclinical or clinical data for each therapeutic agent.

Coagulation management of bleeding trauma patients is changing in German trauma centers: an analysis from the trauma registry of the German Society for Trauma Surgery.

BACKGROUND: Recent findings have emphasized the need for early and aggressive coagulation support in bleeding trauma patients. This study aimed to examine whether blood component transfusion and hemostatic drug administration during acute trauma care have changed in daily practice during the recent years. METHODS: The multicenter trauma registry of the German Society for Trauma was retrospectively analyzed for primarily admitted patients older than 16 years with an Injury Severity Score ≥ 16 who had received at least five red blood cell (RBC) units between emergency room arrival and intensive care unit admission. Administration of fresh frozen plasma and platelet units has been documented since 2002, and use of hemostatic drugs since 2005. RESULTS: From 2002 until 2009 (n = 2,813), the fresh frozen plasma:RBC ratio increased from 0.65 to 0.75 (p = 0.02) and the platelet:RBC ratio from 0.04 to 0.09 (p < 0.0001). A constant increase was also observed regarding the overall use of hemostatic drugs (n = 1,811; 2005-2009) as these were administered to 43.4% of the patients in 2005 and to 60.7% in 2009 (p < 0.0001). Especially, the administration of fibrinogen concentrate (2005: 17.0%, 2009: 45.6%; p < 0.0001) and recombinant factor VIIa (2005: 1.9%, 2009: 6.3%; p = 0.04) showed a marked increase. However, mortality rates remained unchanged during the 8-year study period. CONCLUSIONS: The therapy of bleeding trauma patients has changed in Germany during the recent years toward more aggressive coagulation support. This development continues although grades of evidence are still low regarding most of the changes reported in our study. Randomized controlled trials are needed with respect to blood component therapy using predefined ratios and to the administration of hemostatic drugs commonly used for the severely injured.

Clinical and research issues in neonatal anemia and thrombocytopenia.

PURPOSE OF REVIEW: Anemia and thrombocytopenia are the most common hematological problems in neonates. Red blood cell (RBC) and platelet transfusions are the mainstays of therapy, but data to guide neonatal transfusion practices have been sparse. Recombinant hematopoietic growth factors represent another therapeutic alternative, but their use in this population requires a solid understanding of the developmental differences between fetal and adult hematopoiesis. RECENT FINDINGS: Recently, follow-up studies from children randomized as neonates to either liberal or restrictive RBC transfusion approaches were published. Results of these studies have so far been contradictory and have generated more questions than answers. New developmental stage-specific problems associated with RBC transfusions were also uncovered, such as the transfusion-associated necrotizing enterocolitis. Finally, two thrombopoietin (Tpo) mimetics were approved by the FDA for the treatment of adults with chronic immune thrombocytopenia, thus offering a novel potential therapeutic alternative for thrombocytopenic neonates. SUMMARY: In this review, we will discuss the currently available data regarding neonatal RBC and platelet transfusion thresholds, as well as the potential limitations, and concerns associated with the use of erythropoietin and Tpo mimetics in this patient population. Finally, we will point out specific areas wherein additional research is critically needed.

[Advancement in the preparation of red cell concentrates and platelet concentrates].

Both Japan Society of Blood Transfusion and Cell Therapy and Japan Society of Anesthesiologists have made a "Guideline of Management at Critical Bleeding in the Operating Room" in 2007. Since 2008, Japan Red Cross Blood Center (JRC) introduced leuko-reduction filter and diversion technique to prevent bacterial contamination. This improvement can easily introduce ABO compatible transfusion at critical situation. We proved the safety of transitional anti-A, anti-B antibody at compatible transfusion. 1) anti-A, anti-B antibody of leuko-reduced red cell concentrates (RCC-LR): Due to 90% plasma removal by centrifugation, antibody titer of anti-A, anti-B antibodies in RCC-LR is less than 2 times dilution. This level of antibodies does not cause hemolysis when more than 100 compatible ABO mismatch RCC-LR bags transfused at once. 2) Neutralization of ant-A, anti-B antibody due to A, B substance containing patient's plasma: ABO blood type is composed by glucan antigen, and it is contained in the plasma, saliva and many organs. When ABO incompatible transfusion has been done, transitional anti-A, anti-B antibodies are neutralized by A, B substances. Our experiment showed neutralizing titer 64 times equal volume of ABO incompatible plasma. 3) Anti-A, anti-B antibody titer of Fresh Frozen Plasma (FFP) and Platelet Concentrates (PC): With ABO mismatch transfusion, FFP and PC do not contain incompatible red cells at all. Therefore, the risk of hemolysis will be caused by transitional anti-A, anti-B antibodies. Both with PC and FFP, anti-A, anti-B antibodies keep normal level (average: 16 times dilution). The safe volume of ABO mismatch PC and FFP administration has limited within 3 liters. When such mismatch transfusion necessarily performed, hydration therapy to protect kidney function should be applied immediately after hemostasis. 4) Red Cell Volume in a PC bag: PC in Japan have processed by single donor apheresis alone since 2004. Our results showed that each PC bag contains less than 5 mm(-3) of RBCs. If this level of RBCs caused hemolysis in ABO mismatch patient, it is too small to cause DIC or renal failure.

Induced pluripotent stem cell-derived human platelets: one step closer to the clinic.

The era of induced pluripotent stem (iPS) cells carries with it the promise of virtually unlimited sources of autologous cells for regenerative medicine. However, efficiently differentiating iPS cells into fully functional mature cell types remains challenging. A new study reporting the formation of fully functional platelets from human iPS (hiPS) cells improves upon recent efforts to generate this enucleated cell type, which remains in high demand for therapeutic transfusions. Notably, their lack of nucleus renders platelets unable to retain the pluripotent or tumorigenic properties of iPS cells.

Emerging bone healing therapies.

Fracture healing is a biologically optimized process. Despite the expectation of unimpaired healing, approximately 5% to 10% of the 7.9 million fractures sustained annually in the United States have difficulty achieving union. Not only does this cause morbidity for patients, but also enormous healthcare and socioeconomic costs. Hence, there is a compelling need to find novel therapies to enhance fracture healing. In this article, we summarize current data on therapies to enhance skeletal healing and review their suggested biologic functions, proposed clinical applications, and known efficacies.