Abstract Objective of this proposal is to determine clinical potentials for low-level laser therapy (LLLT) of neonatal thrombocytopenia (NATP). NATP can be caused by a variety of etiology and places newborns at a high risk of intracranial hemorrhage. No drugs or therapies are currently available for NATP in general, apart from platelet transfusion. We recently discovered that whole body illumination with low power, near infrared lasers at specific settings could vigorously enhance platelet regeneration in both adult and neonatal mice with a severe platelet drop. LLLT accelerated and enhanced proplatelet formation in polyploid megakaryocytes (MKs) by bolstering not only mitochondrial biogenesis but also mitochondrial activity, resulting in a significantly higher rate of platelets generated from individual MKs. Noninvasive whole body LLLT alleviated thrombocytopenia and normalized bleeding times in multiple thrombo- cytopenia murine models, concurrent with improved homeostasis of hematopoietic stem cells and progenitors. In this proposal, we will corroborate LLLT's ability to increase platelet production in umbilical cord human CD34+ stem cells (cHSCs) ex vivo and elucidate the underlying mechanism. We will then stimulate local platelet biogenesis by a newly engineered LLL device called E-plate (Enhancer of platelets) in newborn piglets with different skin colors, at various anatomic locations, and in varying times. Finally, allo-immune thrombocytopenia as a model NATP will be induced in newborn piglets, which are similar in size to human newborns, by daily injection of anti-platelet antibody. Therapeutic efficacy of LLL will be evaluated in the piglets by whole body or liver alone illumination using either multiple E-plates or a single E-plate. The proposed studies could provide valuable information with respect to light penetration, safety, and clinical potentials of the newly engineered E-plate. This drug-free, painless, safe, and noninvasive modality, if successful, could significantly reduce the number of platelet transfusions in newborns with severe thrombocytopenia and greatly improve the outcome of infant cares in the neonatal intensive care unit.