Platelets that are not bone marrow-derived, platelet variants, megakaryocytes, megakaryocytes variants, and products derived from platelets, megakaryocytes or their variants, and admixtures, namely, extracellular vesicles or exosomes, all the foregoing for medical or clinical use; platelet variants for medical or clinical use; pharmaceutical and drug delivery compositions comprising platelet variants for the treatment of tumors, immune-oncology, hematology, cardiovascular, inflammatory, immune and autoimmune diseases, conditions, or responses, critical care disorders, conditions and injuries, solid organ transplantation, wound healing, neurological disorders and orthopedics; Pharmaceutical compositions for drug delivery comprising non bone marrow-derived platelets, platelet variants for treatment of tumors, immune-oncology, hematology, cardiovascular, inflammatory, immune and autoimmune diseases, conditions, or responses, critical care disorders, conditions and injuries, solid organ transplantation, wound healing, neurological disorders and orthopedics; pharmaceutical compositions comprising platelet variants for transfusion in oncology, trauma and surgery; platelet variants for delivering proteins, antibodies, nucleic acids and other drugs to tumors, sites of vascular injury and inflammation, immune-oncology, hematology, cardiovascular, inflammatory, immune and autoimmune diseases, conditions, or responses, critical care disorders, conditions and injuries, solid organ transplantation, wound healing, neurological disorders and orthopedics; platelet variants for the treatment of tumors, immune-oncology, hematology, cardiovascular, inflammatory, immune and autoimmune diseases, conditions, or responses, critical care disorders, conditions and injuries, solid organ transplantation, wound healing, neurological disorders, and orthopedics; platelet variants as source for growth factors for medical or clinical use; compositions comprising viral vectors for medical or clinical use