Spotlights on the trends in performance assessment of qualitative in vitro diagnostic medical devices in transfusion medicine

For reliable clinical decisions in transfusion medicine, assessing the performance of qualitative tests performed in medical laboratories is critical. When false results are reported, these can lead to an adverse reaction to blood components. Good performance assessment practices are essential for this kind of scenario, and they still remain as one of the many unmet high-priority challenges in this area. This paper aims to provide an overview of the current trends in this field. A review of the IFCC-IUPC. qualitative vocabulary was carried out, and a particular focus was given to the evaluation protocols CLSI EP12-A3 and Eurachem AQA, such as the European Union Regulation for class D in vitro diagnostic medical devices. There is a consistency between the current protocols and recognized performance assessment principles, which are mandatory in transfusion service labs. We believe that a revised imprecision interval approach and models based on emerging qualitative test types may prove beneficial in the long run. It is also important to emphasize the uncertainty of proportions to mitigate the risk of misclassification.

Hematological toxicities of immune checkpoint inhibitors and the impact of blood transfusion and its microbiome on therapeutic efficacy and recipient's safety and survival outcome:A systematic narrative appraisal of where we are now!

Classically, patients with solid and hematologic malignancies have been treated with a combination of chemotherapy with or without a holistic targeted strategy using approved conventional therapy. While the evidence-based use of Immunomodulatory drugs and Immune checkpoint inhibitors (ICIs), including those targeting the PD-1, PD-L1 and CTLA-4, have reshaped the treatment paradigm for many malignant tumors and significantly stretched the life expectancy of patients, as for any interventional therapy, the rise in ICI applications, was associated with the observation of more immune-related hematological adverse events. Many of these patients require transfusion support during their treatment in line with precision transfusion. It has been presumed that transfusion-related immunomodulation (TRIM) and the microbiome can pose immunosuppressive effects on the recipients. Looking to the past and beyond and translating available data into practice in the evolving role of pharmaceutical therapy to ICI-receiving patients, we performed a narrative review of the literature on the immune-related hematological adverse events of ICIs, immunosuppressive mechanisms linked to blood product transfusions, as well as the detrimental impact of transfusions and its related microbiome on the sustained efficacy of ICIs and the patients' survival outcomes. Recent reports are pointing to the negative impact of transfusion on ICI response. Studies have concluded that packed RBC [PRBC] transfusions lead to an inferior progression-free and overall survival in patients with advanced cancer receiving ICIs, even after adjustments for other prognostic variables. The attenuation of the effectiveness of immunotherapy likely results from the immunosuppressive effects of PRBC transfusions. It is, therefore, wise to look retrospectively and prospectively at the impact of transfusion on ICI effects and adopt, in the interim, a restrictive transfusion strategy, if applicable, for those patients.

T-cell lymphocytopenia: an omnipresent predictor of morbidity and mortality in consequence of SARS-CoV disease and influenza A infections

We proposed T-cell lymphocytopenia as a strategic predictor of serious coronavirus and influenza infections. Our preeminent goal was to determine whether a degree of T-cell lymphopenia would identify a distinct threshold cell count to differentiate between severe and non-severe infections. We codified an Index Severity Score to exploit an association between T-cell cytopenia and the grade of disease activity.

Principal result

A T-cell count of 560 cells/uL or below signified a trend towards advanced disease.

Key findings and conclusions

The T-cell threshold >560 cells/uL discriminated 85.7% specificity of the lesser viral infections and <=560 cells/uL identified 100% sensitivity of severe infections or death. The positive predictive value of this threshold test was 92.9%.•

T-cell apoptosis and sequestration are two of the primary mechanisms of T-cell lymphodepletion.

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There is potential for the T-cell threshold at <=560 cells/uL to become a standard to differentiate disease severity.

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Future research should explore correlations between the T-cell threshold, medical outcomes of treatment, Cytokine Release Syndromes, cytokine levels, inflammatory and coagulation markers.

Cryopreservation of apheresis platelets treated with riboflavin and UV light

BACKGROUND

Pathogen reduction technology (PRT) is increasingly used in the preparation of platelets for therapeutic transfusion. As the Czech Republic considers PRT, we asked what effects PRT may have on the recovery and function of platelets after cryopreservation (CP), which we use in both military and civilian blood settings.

STUDY DESIGN AND METHODS

16 Group O apheresis platelets units were treated with PRT (Mirasol, Terumo BCT, USA) before freezing; 15 similarly collected units were frozen without PRT as controls. All units were processed with 5-6% DMSO, frozen at - 80 °C, stored > 14 days, and reconstituted in thawed AB plasma. After reconstitution, all units were assessed for: platelet count, mean platelet volume (MPV), platelet recovery, thromboelastography, thrombin generation time, endogenous thrombin potential (ETP), glucose, lactate, pH, pO2, pCO2, HCO3, CD41, CD42b, CD62, Annexin V, CCL5, CD62P, and aggregates > 2 mm and selected units for Kunicki score.

RESULTS

PRT treated platelet units had lower platelet number (247 vs 278 ×10⁹/U), reduced thromboelastographic MA (38 vs 62 mm) and demonstrated aggregates compared to untreated platelets. Plasma coagulation functions were largely unchanged.

CONCLUSIONS

Samples from PRT units showed reduced platelet number, reduced function greater than the reduced number would cause, and aggregates. While the platelet numbers are sufficient to meet the European standard, marked platelets activation with weak clot strength suggest reduced effectiveness.

SARS-CoV-2 and cancer: The intriguing and informative cross-talk

The COVID-19 pandemic caused by the SARS-CoV-2 virus has significantly disrupted and burdened the diagnostic workup and delivery of care, including transfusion, to cancer patients across the globe. Furthermore, cancer patients suffering from solid tumors or hematologic malignancies were more prone to the infection and had higher morbidity and mortality than the rest of the population. Major signaling pathways have been identified at the intersection of SARS-CoV-2 and cancer cells, often leading to tumor progression or alteration of the tumor response to therapy. The reactivation of oncogenic viruses has also been alluded to in the context and following COVID-19. Paradoxically, certain tumors responded better following the profound infection-induced immune modulation. Unveiling the mechanisms of the virus-tumor cell interactions will lead to a better understanding of the pathophysiology of both cancer progression and virus propagation. It would be challenging to monitor, through the different cancer registries, retrospectively, the response of patients who have been previously exposed to the virus in contrast to those who have not contracted the infection.

Therapeutic Use of Convalescent Plasma in COVID-19 Infected Patients with Concomitant Hematological Disorders

The use of convalescent plasma (CP) from individuals recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a promising therapeutic modality for the coronavirus disease 2019 (COVID-19). CP has been in use for at least a century to provide passive immunity against a number of diseases, and was recently proposed by the World Health Organization for human Ebola virus infection. Only a few small studies have so far been published on patients with COVID-19 and concomitant hematological malignancies (HM). The Italian Hematology Alliance on HM and COVID-19 has found that HM patients with COVID-19 clinically perform more poorly than those with either HM or COVID-19 alone. A COVID-19 infection in patients with B-cell lymphoma is associated with impaired generation of neutralizing antibody titers and lowered clearance of SARS-CoV-2. Treatment with CP was seen to increase antibody titers in all patients and to improve clinical response in 80% of patients examined. However, a recent study has reported impaired production of SARS-CoV-2-neutralizing antibodies in an immunosuppressed individual treated with CP, possibly supporting the notion of virus escape, particularly in immunocompromised individuals where prolonged viral replication occurs. This may limit the efficacy of CP treatment in at least some HM patients. More recently, it has been shown that CP may provide a neutralising effect against B.1.1.7 and other SARS-CoV-2 variants, thus expanding its application in clinical practice. More extensive studies are needed to further assess the use of CP in COVID-19-infected HM patients.

Polycythaemia vera: molecular genetics, diagnostics and therapeutics

Polycythaemia vera is one of several classical myeloproliferative neoplasms that may occur in a juvenile onset or late-onset adult forms. It is linked to specific genetic mutations that cause a deleterious elevation in the patient's red cell mass. The discourse on genetics includes an exposé on the molecular biology of the disease and how a shared JAK2 V617F mutation can co-exist among three distinct neoplasms. Concepts of genetics and immunology help define the origin and behaviour of the disease: the tracking of allele burdens of mutations (genetic dosage), the timing or order of acquired mutations, the import of bystander mutations and the onco-inflammatory response; all theories are invoked to explain the progression of disease severity and potential transformational leukaemia. The World Health Organization's diagnostic criteria are accessed to focus on the subtleties of the Hb laboratories and sifting through the challenging listing of differential diagnoses that mimic PV, and our report includes an overview of manual and automated phlebotomy (erythrocytapheresis) procedures, enumerating their clinical indications, significance of temporary phlebotomy resistance and optimizing safety/ efficacy, quality and cost. Stratification of low and high-risk disease distinguishes when to commence chemo-cytoreductive therapy in the high-risk patient to prevent thrombotic complications. Drug resistance is circumvented by artfully switching drugs or using novel drug designs.

WITHDRAWN: New Generation of vaccines and convalescent plasma therapy for management of CoV-2: Perspectives from the UK and potential deployment in the current global pandemic

The Publisher regrets that this article is an accidental duplication of an article that has already been published, https://doi.org/10.1016/j.transci.2021.103051. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

On the Quest for In Vitro Platelet Production by Re-Tailoring the Concepts of Megakaryocyte Differentiation

The demand of platelet transfusions is steadily growing worldwide, inter-donor variation, donor dependency, or storability/viability being the main contributing factors to the current global, donor-dependent platelet concentrate shortage concern. In vitro platelet production has been proposed as a plausible alternative to cover, at least partially, the increasing demand. However, in practice, such a logical production strategy does not lack complexity, and hence, efforts are focused internationally on developing large scale industrial methods and technologies to provide efficient, viable, and functional platelet production. This would allow obtaining not only sufficient numbers of platelets but also functional ones fit for all clinical purposes and civil scenarios. In this review, we cover the evolution around the in vitro culture and differentiation of megakaryocytes into platelets, the progress made thus far to bring the culture concept from basic research towards good manufacturing practices certified production, and subsequent clinical trial studies. However, little is known about how these in vitro products should be stored or whether any safety measure should be implemented (e.g., pathogen reduction technology), as well as their quality assessment (how to isolate platelets from the rest of the culture cells, debris, microvesicles, or what their molecular and functional profile is). Importantly, we highlight how the scientific community has overcome the old dogmas and how the new perspectives influence the future of platelet-based therapy for transfusion purposes.

Trends and targets of various types of stem cell derived transfusable RBC substitution therapy: Obstacles that need to be converted to opportunity

A shortage of blood during the pandemic outbreak of COVID-19 is a typical example in which the maintenance of a safe and adequate blood supply becomes difficult and highly demanding. So far, human RBCs have been produced in vitro using diverse sources: hematopoietic stem cells (SCs), embryonic SCs and induced pluripotent SCs. The existing, even safest core of conventional cellular bioproducts destined for transfusion have some shortcoming in respects to: donor -dependency variability in terms of hematological /immunological and process/ storage period issues. SCs-derived transfusable RBC bioproducts, as one blood group type for all, were highly complex to work out. Moreover, the strategies for their successful production are often dependent upon the right selection of starting source materials and the composition and the stability of the right expansion media and the strict compliance to GMP regulatory processes. In this mini-review we highlight some model studies, which showed that the efficiency and the functionality of RBCs that could be produced by the various types of SCs, in relation to the in-vitro culture procedures are such that they may, potentially, be used at an industrial level. However, all cultured products do not have an unlimited life due to the critical metabolic pathways or the metabolites produced. New bioreactors are needed to remove these shortcomings and the development of a new mouse model is required. Modern clinical trials based on the employment of regenerative medicine approaches in combination with novel large-scale bioengineering tools, could overcome the current obstacles in artificial RBC substitution, possibly allowing an efficient RBC industrial production.

An Overview of Current Position on Cell Therapy in Transfusion Science and Medicine: From Fictional Promises to Factual and Perspectives from Red Cell Substitution to Stem Cell Therapy

Stem cell therapy is a relatively novel field of investigation, in which either differentiated cells or stem cells capable of differentiation are transplanted into an individual with the objective of yielding specific cell types in the damaged tissue and consequently restoring its function. The most successful example of cell therapy is hematopoietic stem cell transplantation, leading to regeneration of a patient's blood cells, now a widely established procedure for many oncologic and non-oncologic diseases. Innovative cell-based therapies are being developed to replace, regenerate or repair injured, absent, or diseased tissues and organs. However, cell therapy bioproducts are based on their inherent biological features such as proliferation, migratory, capability, plasticity, and capacity of self-renewal, posing serious challenges during such bioproduct development. The extraordinary promise of stem cells for future treatments of otherwise intractable diseases has raised great hope and expectations in patients, advocates, physicians, and researchers alike. However, despite thousands of scientific publications and research programs, increased efforts need to be put into the identification of the factors involved, biological mechanisms and materials that affect safety/ efficacy, and into the design of cost-effective methods for the harvesting, expansion, manipulation and purification of the cells.

Update on newer approaches to prevent or treat COVID-19 infection: What we all need the most right now!!

COVID-19 convalescent plasma (CCP) therapy involves the use of circulating antibodies administration from recovered COVID 19 patients as a practical strategy to provide immediate passive immunity in susceptible recipients in need. Global concern over the potential for “second” or “third” waves of infection to occur before effective vaccines or drug therapies are available has many looking at other biological sources for large-scale production of neutralizing SARS-CoV-2 antibodies. This report summarizes some of the novel strategies for developing alternative safe sources of therapeutic autologous antibodies from COVID ‐19 infected patients, and provides some original thoughts on how to rapidly implement a safe passive immunity in those COVID-19 patients who are most in need of intervention. COVID-19 antibodies can be isolated or delivered using a number of other techniques including: plasmapheresis, plasma cryoprecipitate reduced (cryosupernatant), antibody hyperconcentrates and advanced cell-based delivery systems. While these proposed technological options may, in some cases, be theoretical, the growing concern over the rapid spread of the SARS-CoV-2 virus has prompted many to pursue innovative and creative solutions to reduce the mortality and morbidity resulting from the current global pandemic. A comparative analysis of various strategies currently in use deserved exploring and this highlighted separately as the essential part of this concise theme.

Spotlight on the current perspectives on applications of human blood cell culture and organoids: Introductory remarks

Culture of blood cells, mainly erythrocytes, at industrial levels complying with cGMP regulations, aim to make them available, at large scale, any time and everywhere, when needed for transfusion, or laboratory applications. Understanding how blood cells differentiate and develop in-vivo, and mechanisms of differentiation and growth factors, has opened newer strategies for in-vitro culture from multipotent stem cells or immortalized lines. This offers interesting perspectives for obtaining such cultured bioproduct cells for medical applications. In addition, many attempts for preparing platelets in-vitro from megakaryocyte culture have been reported. Nevertheless, the quantities of functional viable platelets obtained are still not sufficient to envisage transfusion applications. Other strategic approaches concern culture of organoids, which can synthesize functional blood proteins, but still significant scale-up of yield needs to be addressed. Finally, considerable advances have been made in culturing specific lymphocytes for personalized immunotherapy of some cancer patients with highly promising results in certain applications. This concise mini report focuses on the progress made in these directions, and attempts are made to describe some newer perspectives.

In vitro platelet production for transfusion purposes: Where are we now?

Over the last decade there has been a worldwide increase in the demand of platelet concentrates (PCs) for transfusion. This is, to a great extent, due to a growing and aging population with the concomitant increase in the incidence of onco-hematological diseases, which require frequent platelet (PLT) transfusions. Currently, PLTs are sourced uniquely from donations, and their storage time is limited only to a few days. The necessity to store PCs at room temperature (to minimize loss of PLT functional integrity), poses a major risk for bacterial contamination. While the implementation of pathogen reduction treatments (PRTs) and new-generation PLT additive solutions have allowed the extension of the shelf life and a safer PLT transfusion product, the concern of PCs shortage still pressures the scientific community to find alternative solutions with the aim of meeting the PLT transfusion increasing demand. In this concise report, we will focus on the efforts made to produce, in in vitro culture, high yields of viable and functional PLTs for transfusion purposes in a cost-effective manner, meeting not only current Good Manufacturing Practices (cGMPs), but also transfusion safety standards.

The secrets of human stem cell-derived transfusable RBC for targeted large-scale production and clinical applications: A fresh look into what we need most and lessons to be learned

Blood transfusion, using the safest conventional blood bioproducts, is an irreplaceable part of substitution therapy. It is considered the most essential supportive clinical intervention aimed to restore the health of patients in need. Nevertheless, numerous unresolved problems are still associated with current blood substitution therapy. To alleviate our dependency on blood donors, many investigators have been focusing on the quest for stem cell-derived blood cells in line with major developments in the field of regenerative medicine. The main objective is to provide a safe and highly standardized universal cultured red cell concentrate [CRBC] for all clinical applications, regardless of blood groups. Currently, we are close to overcoming some of the main obstacles in culturing cells. This concise report is a prelude to the immortalized cell lines that are ready for in vivo clinical trials. It is only through the sharing of experimental ideas and knowledge-based strategies that we will be able to achieve such an enormous task and better understand ‘’the one for all concept’’ of CRBCs and their universal usage in all clinical settings.

Covid-19, induced activation of hemostasis, and immune reactions: Can an auto-immune reaction contribute to the delayed severe complications observed in some patients?

Covid-19 is characterized by weak symptoms in most affected patients whilst severe clinical complications, with frequent fatal issues, occur in others. Disease severity is associated with age and comorbidities. Understanding of viral infectious mechanisms, and antibody immune response, can help to better control disease progression. SARS-CoV-2 has a major impact on the Renin Angiotensin Aldosterone System (RAAS), through its binding to the membrane cellular glycoprotein, Angiotensin Converting Enzyme-2 (ACE-2), then infecting cells for replication. This report hypothesizes the possible implication of an autoimmune response, induced by generation of allo- or autoantibodies to ACE-2, or to its complexes with viral spike protein. This could contribute to some delayed severe complications occurring in affected patients. We also propose a strategy for investigating this eventuality.

WITHDRAWN: Convalescent plasma, an apheresis research project targeting and motivating the fully recovered COVID 19 patients: A rousing message of clinical benefit to both donors and recipients alike

The Publisher regrets that this article is an accidental duplication of an article that has already been published, https://doi.org/10.1016/j.transci.2020.102794. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Opportunities for standardization of cold stored, low-titre group O WB products

Interest in the use of cold-stored low-titre, group O whole blood (LTO-WB) in civilian trauma medicine has motivated regional and national blood services to explore the operational implications of providing this product to their hospital customers. While simpler to produce, store and administer than conventional blood components, LTO-WB is only distributed by a limited number of civilian blood services to date. To improve the availability of LTO-WB, there are still a number of clinical and basic research challenges that need to be addressed including 1. Standardization of the methods and definitions for what constitutes "low-titre" whole blood; 2. Updating regulatory standards for the in vitro quality of cold stored whole blood; 3. Development of standards for the post-storage component separation of red blood cells from cold stored whole blood; and 4. Optimization of the logistics for collection and distribution of cold stored whole blood in regional and national blood systems. The main objective of this concise overview is to highlight the opportunities for future research and product development efforts that will improve the availability of standardised LTO-WB products in emergency cases to the benefit of all concerned.

Emergency Supply Policy of Cryopreserved RBC and PLT: The Czech Republic Concept

Supply of blood for urgent substitution is a strategic logistical problem for the military medical services across the world. The limited shelf life of blood- derived bioproductsin the liquid state and the need for special transport and use conditions, apart from donor and donations availability are among the causes for concern. To solve these problems many national health-care authorities implemented the national emergency blood crisis policy, to get a large amount of blood at any time at any place in the case of disaster, terrorist attack or war. The civil therapeutic problems in immunohematolgy cases can also be solved by stocks of fresh and cryopreserved homologous or autologous blood for patients with rare RBCs antigens or HLA / HPA platelet refractoriness with no chance to use common blood. The short shelf life of fresh platelets limits their efficient inventory management and availability during a massive transfusion protocol. Building an inventory of frozen blood components can mitigate the risk of insufficient availability. Since the beginning of the century in the Czech Republic, used, like other countries, the use of of cryopreserved blood-derived bioproducts has become the current method used to overcome the shortages of a timely supply. The Military University Hospital, Prague, and its bank of cryopreserved blood have been operating under this policy since 2006. There is currently a stock of frozen RBCs for military reserve, for a national blood crisis and, also, a stock of rare RBC units. For crisis management there are also stored, frozen PLTs, which are used in the treatment of heavily bleeding polytrauma patients. Both the containment and research development mitigation policy programs are in place for civil / military emergency situations. Even pathogen reduced frozen PLTs and frozen RBCs were successfully investigated for clinical use if demands arose. Currently, it is possible to meet operational demand while reducing the number of resupply transports and loss of products due to expiration. A lesson has been learned from the current containment, reseach and mitigation programs of efficient blood supply management with cryopreserved blood and blood derived bioproducts.

NEW HORIZONS ON STEM CELL CRYOPRESERVATION THROUGH THE ARTIFICIAL EYES OF CD 34+, USING MODERN FLOW CYTOMETRY TOOLS

Hematopoietic stem cell (HSC) cryopreservation is a critical step in autologous and cord blood transplantation (CBT). In most circumstances, cryopreservation is performed in a mixture containing dimethyl sulfoxide (DMSO), since DMSO is necessary to secure cell viability. Most centers use a controlled rate (slow) freezing before the long-term storage at vapor phase liquid nitrogen (LN₂) temperatures (≤ -160 °C). The primary objectives for laboratories supporting HSCT programs are to provide secure storage for leukapheresis and cord blood products, and to adequately characterize the functional properties of the grafts before their infusion. In the autologous setting, the large majority of the published results dealt with the assessment of the graft before cryopreservation. On the contrary, in CBT, before a CB unit is released, a sample obtained from a contiguous segment of that CB unit needs to be tested to verify HLA type and cell viability. The effects of graft handling, cryopreservation, storage and thawing on the recovery of CD34+ cells needs to be carefully analyzed and standardized on a global level. Some technical unresolved issues still limit the application of the ISHAGE derived single platform flow cytometry protocol for the assessment of the thawed material; based on these considerations, an adaptation of both the acquisition setting and the gating strategyis necessary for reliable measurement of CD34-expressing HSC in cryopreserved grafts. Artificial intelligence applied to "big data" may provide a new tool for improving advanced processing procedures and quality management guidelines in this area of investigation.

Poor economics - Transforming challenges in transfusion medicine and science into opportunities

The prospect of cryopreservation of cellular components in the low and medium income (poor economics) part of the world absolutely needs a solid and sustainable infrastructure to build on in line with science, technology and globalization, based on rational thinking, standardization and harmonization of future advances we are currently witnessing in limited parts of the world. With the stepwise development of the healthcare stimulated by the 2012 UN Universal Health Coverage (UHC) program and supported by WHO Model List of Essential Medicines (EM) and Essential in vitro Diagnostics (ED), a slowly growing number of countries will reach a point where quality cryopreservation of cellular components becomes feasible as an advance for implementing specific health care visions, policies and strategies in line with the Sustainable Development Goals 2016-2030.

Optimizing the supply of whole blood-derived bioproducts through the combined implementation of cryopreservation and pathogen reduction technologies and practices: An overview

The essential historical knowledge and expertise developed over the past 5-6 decades on the safety / efficacy of conventional blood components therapy by blood transfusion establishments have guided the development of validated methods which have ensure optimal safety margins for frozen blood and its bioproducts with or even without pathogen reduction. Newer generations of pathogen reduced frozen red blood cell, plasma and platelet products and the standardised and safer pooling of human platelet lysate are now become available for potential clinical use. These types of whole blood-derived bioproducts not only reduce the risk of transmission of range of pathogenic blood-borne pathogen. As cryopreservation can be combined with PRT without significantly compromising in vitro quality characteristics or physiological capabilities, it allows us to maximize the available inventory of these blood products in both civil and military trauma settings. The main objective of this overview is to update readers and scientific / medical communities of the various building blocks needed to optimally grantee the pathogen safety of whole blood-derived bioproducts, with minimal untoward events to the recipients. While this is an emerging area, we are seeing the numerous potential opportunities that cryopreservation and pathogen inactivation can have on the transfused patient outcomes. This manuscript is informed by recent publications on this topic.

Vitamin B12 deficiency and metabolism-mediated thrombotic microangiopathy (MM-TMA)

Thrombotic microangiopathies (TMA) are characterized by microangiopathic hemolytic anemia, thrombocytopenia and organ damage resulting from mechanical factors, accumulation of the ultra-large von Willebrand factor multimers or complement-mediated abnormalities. Severe acquired vitamin B12 (Cobalamin - Cbl) deficiency or congenital defective Cbl metabolism could lead to a picture that mimics TMA. The later has been termed metabolism-mediated TMA (MM- TMA). This confusing picture is mediated partly by the large red cell fragmentation coupled with reduced platelet production in the absence of vitamin B12 and partly by the accumulated byproducts and metabolites that induce endothelial injury and hence organ damage. Expensive and complicated treatment for TMA is often initiated on an empiric basis, pending the results of confirmatory tests. In contrast, vitamin B12 Pseudo-TMA and MM-TMA could be treated with proper vitamin B12 supplementation. It is therefore important to identify these disorders promptly. The recent availability of a validated scoring system such as the PLASMIC score uses simple clinical and laboratory parameters. As it incorporates the mean corpuscular volume in its laboratory parameters, this helps in the identification of pseudo and MM-TMA. Perhaps some minor modification of this scoring system by changing the parameters of hemolysis to include reticulocytosis and rather than and/or other hemolytic parameters could even help refine this identification.

Platelet-derived bio-products: Classification update, applications, concerns and new perspectives

Platelet derived bio-products in the form of platelet rich plasma, plasma rich in growth factors, or plasma-free platelet releasates, are being studied worldwide with the aim of proving their efficacy in tissue regeneration within many different clinical areas, such as traumatology, maxillofacial surgery, ophthalmology, dermatology and otorhinolaryngology, amongst others. The current lack of consensus in the preparation method and application form, or in the quality assessment of each bio-product, precludes adequate interpretation of the relevance of reported clinical outcomes, and, while many in clinicians are very positive about them, many are sceptic. Relevant aspects of these products are considered to propose a classification nomenclature which would aid a comprehensive comparison of clinical outcomes of bio-products of the same characteristics. Finally, the uses of platelet-derived bio-products in in vitro culture (for cell therapy purposes) as a substitute of animal-origin sera, and other future perspectives of applications of platelet-derived bio-products are discussed.