Swine and Bat Pleiotrophin (PTN) is a secreted heparin-binding growth factor that plays important roles in cell proliferation, differentiation, angiogenesis, and tissue repair. PTN belongs to a small family of heparin-binding growth-associated proteins, which includes midkine (MK) as its closest related family member. In both swine (Sus scrofa) and bats, the pleiotrophin protein is identical at the amino acid level, indicating strong evolutionary conservation and suggesting similar biological functions across these species. PTN interacts with several cell surface receptors, including receptor protein tyrosine phosphatase beta/zeta (RPTPβ/ζ), anaplastic lymphoma kinase (ALK), and syndecans, activating signaling pathways that regulate cell migration, neurite outgrowth, angiogenesis, and extracellular matrix interactions. PTN is expressed in developing tissues, endothelial cells, macrophages, and stromal cells, where it contributes to vascular development, tissue regeneration, and immune-related processes. In swine, PTN is relevant to studies of vascular biology, tissue repair, and developmental processes, while in bats it may contribute to tissue regeneration and immune responses associated with viral tolerance and tissue homeostasis. Because pigs are widely used as large-animal models for human cardiovascular and regenerative biology, and bats are studied for their unique immune and regenerative capacities, characterization of pleiotrophin in these species supports research on angiogenesis, neural and tissue development, and conserved growth factor signaling mechanisms across mammals.