Is proteomics still knockin' on the hematological door?
Venue: Proteomics. Clinical applications

Michel Prudent Proteomics has not totally invaded the clinical world, and in particular the hematology, yet. The door was opened more than 10 years ago  and proteomics was welcomed even though the direct benefits were not so straightforward. Behind the expertise needed to carry out proteomic workflow and to handle liquid chromatography systems and mass spectrometers, which may require a dedicated laboratory for services, the main issue remains the biological questions and the clinical relevance of the approach; in other words, to carry out hypotheses driven research. Several scientists and physicians are now working at the interface of omics and clinics, and they understand the problematics on both side. This was, and still is, a major challenge for many of us, and the term translational proteomics has been coined. Therefore, the meeting of scientists from different worlds and the evolution of the minds have favored the research on specific cases where proteomics (and omics science in a broader sense) affords its best to provide answers to clinical questions. What is interesting and challenging for us, physicians and scientists, is the knowledge hidden "inside" the proteomes. Proteomics is more than the reporting of a list of proteins, it is the analysis of proteoforms (post translational modifications, deletions, variants and so on) and the protein protein interactions. It enables to study and to evaluate the roles of proteins in biological systems, and more precisely, in complex biological systems. The shift is impressive: it evolves from one protein to the complexity of the protein webs. A special issue dedicated to ,Hematological Proteomics" could be viewed as a topic on biomarker discovery in blood. This is not the case! Without being exhaustive, it covers a wide picture of hematology in the physiological and pathological aspects (non malignant) of blood cells, the impact of surgery on blood and coagulation, and transfusion needs; thus, ,Hematological Proteomics" shows the shift of paradigms from a catalogue of proteins to biomarker discovery with the aim to try to decipher molecular pathways. Of course, the various sides of this issue are working together since several hematological disorders may be studied using proteomic tools. In addition, many patients are treated with transfusion of blood products, notably red blood cells, platelets and plasma. Basic and clinical knowledge of these products as well as of the process/storage lesions are thus required to precisely and efficiently treat patients. A few examples are proposed within this issue. The transfusion medicine is currently taking benefit of the proteomics and omics [2,3] even though it remains at the research level and has started to be considered in a limited number of clinical trials. The last decade has provided ample evidence on the benefits of omics in science of managing blood from donors and for patients. It provides different clues and strategies based on advanced analytical data (far behind the gold standards that fail to detail acute phenomena) that should be used to better manage the donors, to better manage the process and storage, to better manage the distribution or the segregation of the products taking into account the blood products' and patients' characteristics. The contributions of Rinalducci et al. Schubert et al. Tzounakas et al. Thiele et al. Osman et al. and our works present in this special issue of Proteomics Clinical Applications perfectly illustrate our words. Of course, proteomic data can also benefit to the study of blood cells, mainly platelets and red blood cells from a physiological and pathophysiological view. The former contributes to improve the chemical and biochemical knowledge (based on exploratory research) of the cells where surprisingly a lot of pathways have still to be discovered and deciphered, especially on red blood cells and platelets where new mechanisms are regularly pictured out. As for the hematological diseases, proteomics has an open door to impact the health and care of patients. It passes by the diagnosis of rare or poorly documented diseases based on biomarker discovery, and by the comprehensive analyses of cellular behavior and injuries for treatments.