Optimising platelet secretomes to deliver robust tissue specific regeneration

Promoting cell proliferation is the cornerstone of most tissue regeneration therapies. As platelet‐based applications promote cell division and can be customised for tissue‐specific efficacy, this makes them strong candidates for developing novel regenerative therapies. Therefore, the aim of this study was to determine if platelet releasate could be optimised to promote cellular proliferation and differentiation of specific tissues. Growth factors in platelet releasate were profiled for physiological and supra‐physiological platelet concentrations. We analysed the effect of physiological and supra‐physiological releasate on C2C12 skeletal myoblasts, H9C2 rat cardiomyocytes, human dermal fibroblasts (HDF), HaCaT keratinocytes and chondrocytes. Cellular proliferation and differentiation were assessed through proliferation assays, mRNA and protein expression. We show that supra‐physiological releasate is not simply a concentrated version of physiological releasate. Physiological releasate promoted C2C12, HDF and chondrocyte proliferation with no effect on H9C2 or HaCaT cells. Supra‐physiological releasate induced stronger proliferation in C2C12 and HDF cells compared to physiological releasate. Importantly, supra‐physiological releasate induced proliferation of H9C2 cells. The proliferative effects of skeletal and cardiac muscle cells were in part driven by VEGFα. Furthermore, supra‐physiological releasate induced differentiation of H9C2 and C2C12, HDF and keratinocyte differentiation. This study provides insights into the ability of releasate to promote muscle, heart, skin and cartilage cell proliferation and differentiation and highlights the importance of optimising releasate composition for tissue‐specific regeneration

AG5 is a potent non-steroidal anti-inflammatory and immune regulator that preserves innate immunity

12 pages, 5 figures.-- This is an open access article under the CC BY-NC-ND licenseAn archetypal anti-inflammatory compound against cytokine storm would inhibit it without suppressing the innate immune response. AG5, an anti-inflammatory compound, has been developed as synthetic derivative of andrographolide, which is highly absorbable and presents low toxicity. We found that the mechanism of action of AG5 is through the inhibition of caspase-1. Interestingly, we show with in vitro generated human monocyte derived dendritic cells that AG5 preserves innate immune response. AG5 minimizes inflammatory response in a mouse model of lipopolysaccharide (LPS)-induced lung injury and exhibits in vivo anti-inflammatory efficacy in the SARS-CoV-2-infected mouse model. AG5 opens up a new class of anti-inflammatories, since contrary to NSAIDs, AG5 is able to inhibit the cytokine storm, like dexamethasone, but, unlike corticosteroids, preserves adequately the innate immunity. This is critical at the early stages of any naïve infection, but particularly in SARS-CoV-2 infections. Furthermore, AG5 showed interesting antiviral activity against SARS-CoV-2 in humanized miceThis work has been supported by NextGenerationEU Recovery and Resilience Facility (RRF) through the PTI+ Global Health Platform of Spanish National Research Council, grants SGL2103023 (PBA), SGL2103053 (MMA) and SGL2103015 (MM); by Spanish National Research Council through the program “Ayudas extraodinarias a proyectos de investigacion en el marco de las medidas urgentes extraodinarias para hacer frente al impacto económico y social del COVID-19”, grants CSIC-COV19-093 (PBA) and CSIC-COV19-117 (MM); by Generalitat Valenciana through the program “Ayudas urgentes para proyectos de investigación, desarrollo tecnológico e innovación (I+D+i) por la COVID-19”, grant GVA-COVID19/2021/059 (PBA); by the Conference of Rectors of the Spanish Universities, Spanish National Research Council and Banco Santander through the FONDO SUPERA COVID-19, grant CAPriCORn (JSM, JMB); by Severo Ochoa center of excellence program (grant CEX2021-001230-S) (PBA)Peer reviewe

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

Proteomics-wise, how similar are mouse and human platelets?

The field of proteomics and its application to platelet biology, is rapidly and promisingly developing. Platelets (and megakaryocytes) are postulated as biosensors of health and disease, and their proteome poses as a tool to identify the specific health-disease hallmarks. Furthermore, the clinical management of certain pathologies where platelets are active players demands the development of alternative treatments, such is the case in patients where the balance thrombosis-bleeding is compromised, and a proteomics approach might aid at the identification of novel targets. Hereby, the mouse and human platelet proteomes and secretomes from public databases are compared, which shows that human and mouse platelets share a highly conserved proteome, considering identified proteins, and most importantly, their relative abundance. These supports, also interspecies wise, the use of the proteomics tool in the field, substantiated by a growing number of clinically relevant studies in humans or preclinical models. While the study of platelets through proteomics seems accessible and direct (i.e. noninvasive blood sampling, enucleated), there are some points of concern regarding the quality control of samples for such proteomics studies. Importantly, the quality of the generated data is improving over the years, which will allow cross-study comparisons. In parallel, the application of proteomics to the megakaryocyte compartment has a promising but long journey ahead. We foresee and encourage the application of platelet proteomics for diagnostic/prognostic purposes even beyond hematopoiesis and transfusion medicine, and as a tool that will procure the improvement of current therapies and the development of alternative treatment options

Regulation of NKG2D signaling during the epithelial-to-mesenchymal transition

The plasma membrane receptor natural killer group 2 member D (NKG2D) underpins a major mechanism whereby natural killer (NK) and T cells recognize malignant cells. We have recently demonstrated that the epithelial-to-mesenchymal transition, one of the first steps of metastatic dissemination, is under the control of an immunological checkpoint that relies on NKG2D-mediated immune responses