Individuals with type 1 diabetes are at increased cardiovascular risk, particularly in the presence of insulin resistance. A prothrombotic environment is believed to contribute to this risk but thrombotic pathways in type 1 diabetes are only partially understood and the role of platelets is incompletely studied. We hypothesised that platelets from individuals with type 1 diabetes exhibit platelet hyperactivity due to both increased propensity for activation and diminished sensitivity to inhibition, with an amplified maladaptive phenotype in those with insulin resistance.
Blood samples were obtained from individuals with type 1 diabetes enrolled on the 'Double diabEtes and adVErse cLinical Outcome: identification of mechanistic Pathways' (DEVELOP) study with insulin resistance assessed as estimated glucose disposal rate (eGDR), whereby eGDR >8 or <6 mg kg-1 min-1 indicates normal insulin sensitivity or advanced insulin resistance, respectively. Platelet function was analysed using whole blood multiparameter flow cytometry to simultaneously measure three distinct markers of activation, including integrin αIIbβ3 (PAC-1 binding), P-selectin (CD62P) and phosphatidylserine (PS) (Annexin V). Both activation and inhibition responses of the platelets were investigated, which were subjected to the machine learning tool Full Annotation Shape-constrained Trees (FAUST) to characterise platelet subpopulations.
A total of 32 individuals with type 1 diabetes were studied (median age [range] of 24 [18-34] years, 59% male, diabetes duration [mean ± SD] of 14.0 ± 6.3 years and HbA1c of 65.3 ± 14.0 mmol/mol [8.1%]). An increased basal expression, measured as mean fluorescence intensity, of all three platelet activation markers was detected in the type 1 diabetes group compared with healthy control participants (CD62P expression 521 ± 246 vs 335 ± 67; p<0.001, PAC-1 370 ± 165 vs 231 ± 88; p=0.011 and PS 869 ± 762 vs 294 ± 109; p=0.001). Following platelet stimulation, an enhanced activation of these markers was found in the type 1 diabetes group. Within the type 1 diabetes group, those with advanced insulin resistance (eGDR<6 mg kg-1 min-1) showed increased platelet activation compared with individuals with normal insulin sensitivity (eGDR>8 mg kg-1 min-1) with single agonist stimulation CD62P expression (29,167 ± 2177 vs 22,829 ± 2535, p<0.001 and PAC-1 19,339 ± 11,749 and 5187 ± 2872, p=0.02). Moreover, individuals with type 1 diabetes showed reduced sensitivity to platelet inhibition by prostacyclin (PGI2) compared with control participants. Stratification of individuals with type 1 diabetes by insulin resistance demonstrated that in the presence of PGI2, suppression of stimulated CD62P was 17 ± 11% and 33 ± 12% (p=0.02) for advanced insulin resistance and normal insulin sensitivity groups, respectively, with even larger differences demonstrated for PAC-1 (48 ± 17% and 75 ± 7%; p=0.006) and PS exposure (33 ± 12% and 84 ± 10%; p=0.001). Furthermore, FAUST analysis showed that, under basal conditions, there was a different distribution of the eight platelet subpopulations comparing advanced insulin resistance and normal insulin sensitivity groups, with differences also detected following PGI2 inhibition.
Our novel characterisation of platelets in type 1 diabetes shows a maladaptive phenotype with increased basal activity together with hyperactivation following stimulation and diminished responses to inhibition. Insulin resistance appears to further drive this adverse thrombotic phenotype, suggesting an enhanced platelet-driven cardiovascular risk in those with type 1 diabetes and reduced insulin sensitivity.
© 2025. The Author(s).

Millions of platelet units are needed each year to manage thrombocytopenia and other conditions linked to excessive bleeding. These life-saving treatments still depend entirely on donated platelets, despite the numerous shortcomings associated with them, such as limited shelf life, supply shortages, unpredictable functionality, potential for infection, as well as immune-incompatibility issues. These challenges could be overcome with universal donor platelets generated from human induced pluripotent stem cell (hiPSC)-derived megakaryocytes (MKs). We recently developed expandable hiPSC-derived megakaryocytic cell lines (imMKCLs) as a potentially unlimited source for platelet production. imMKCL-derived platelets are functional and have already been tested in patients. In this study, we demonstrate through single-cell time-course imaging that imMKCL maturation is heterogeneous and asynchronous, with only a few imMKCLs generating platelets at any given time under static culture conditions. Using a chemical screen, we identify microtubule (MT) destabilizing agents, including vincristine (VCR), as promising hits, with a larger proportion of VCR-exposed imMKCLs developing proplatelet extensions and more platelets being produced per imMKCL. VCR use reduces the MT content of imMKCLs and results in the production of platelets with a diminished peripheral MT ring structure. Nevertheless, these platelets are functional, as evidenced by their normal response to agonists, their ability to attach to and spread on fibrinogen-coated surfaces, and their capacity to restore hemostasis in vivo. Interestingly, we also observed a negative correlation between the MT content of imMKCLs and platelet yields when we compared imMKCLs differentiated under static conditions (MThigh, low yield) to our turbulence-optimized VerMES™ bioreactor (MTlow, high yield). Taken together, our findings highlight the importance of MT dynamics in megakaryocyte biology, provide a possible explanation for the still poorly understood link between vinca alkaloid in vivo use and thrombocytosis, and bring us closer to realizing the clinical potential of affordable, off-the-shelf hiPSC-derived platelets.
Copyright: © 2025 Nakamura et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Platelets, known for maintaining blood balance, also participate in antimicrobial defense. Upon severeacute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, platelets become hyperactivated, releasing molecules such as cytokines, granule contents, and bioactive lipids. The key effector biolipids produced by platelets include 12-hydroxyeicosatetraenoic acid (12-HETE) and 12-hydroxyeicosatrienoic acid (12-HETrE), produced by 12-lipoxygenase (12-LOX), and prostaglandins and thromboxane, produced by cyclooxygenase-1. While prostaglandin E2 and thromboxane B2 were previously associated with lung inflammation in severe COVID-19, the role of platelet 12-LOX in SARS-CoV-2 infection remains unclear. Using mice deficient for platelets' 12-LOX, we report that SARS-CoV-2 infection resulted in higher lung inflammation characterized by histopathological tissue analysis, increased leukocyte infiltrates, and cytokine production relative to wild-type mice. In addition, distinct platelet and lung transcriptomic changes, including alterations in NOD-like receptor (NLR) family pyrin domain-containing 1 (NLRP1) inflammasome-related gene expression, were observed. Mass spectrometry lipidomic analysis in 12-LOX-deficient-infected mice revealed significant changes in bioactive lipid content, including reduced levels of 12-HETrE that inversely correlated with disease severity. Finally, platelet 12-LOX deficiency was associated with increased morbidity and lower survival rates relative to wild type (WT) mice. Overall, this study highlights the complex interplay between 12-LOX-related lipid metabolism and inflammatory responses during SARS-CoV-2 infection. The findings provide valuable insights into potential therapeutic targets aimed at mitigating severe outcomes, emphasizing the pivotal role of platelet enzymes in the host response to viral infections.

Platelet-cancer cell interactions play a significant role in metastasis. Indeed, they interact via a plethora of receptors, including integrins (e.g. ⍺IIbβ3 and ⍺vβ3), and calcium is essential for both their stability and function. Additionally, calcium plays a significant role in the coagulation cascade, and the implication of calcium level changes on metastatic dissemination and cancer-associated thrombosis are not fully understood. A significant proportion of cancer patients suffer from hypercalcemia and have a worse prognosis. We hypothesized that calcium levels are important for platelet-cancer cell interactions that are mediated via integrins, thus this can be leveraged to disrupt platelet support to the metastatic process. In this study, we assessed the detection of integrins ⍺IIbβ3 and ⍺vβ3 on platelets and cancer cells, platelet function, and the respective receptors implicated in platelet function, while modulating calcium levels. The effect of calcium levels on platelet-cancer cell interactions and cancer cell invasion in vitro was also assessed. Our data demonstrates that calcium levels affect surface integrins, and receptors involved in platelet-cancer cell interactions. In addition, calcium levels significantly affect platelet activation and aggregation. In our experimental scenarios, calcium depletion modulates platelet-cancer cell interaction with MDA-MB-231 breast cancer cells, while hypercalcemic environments did not affect interaction. Meanwhile, hypercalcemia leads to enhanced cancer cell invasion for both MDA-MB-231 and A549 cells in the presence of platelets. Thus, this study provides a greater understanding of the dynamics associated with the effects of calcium and platelet-cancer cell interactions mediated by integrins.
© 2025. The Author(s).