Swine are gaining popularity as a useful large animal model for stem cell therapy for important human diseases or conditions such as myocardial infarction, diabetes, atherosclerosis, traumatic brain injury, retinal damage, and tooth regeneration [21, 22, 23, 24, 25] . Like humans, pigs are an outbred species. As well, they are similar to humans in anatomy, physiology, and immune responses [26, 27, 28, 29] . Additionally, swine can serve as an excellent animal model for influenza virus pathogenesis studies. The clinical manifestations and pathogenesis of influenza in pigs closely resemble to what is observed in humans. Furthermore, the cytokine responses in branchoalveolar lavage (BAL) fluid from swine influenza virus-infected pigs are also identical to that observed in nasal lavage fluids of experimentally infected humans [30] . These observations support that pigs serve as an excellent animal model to study the pathogenesis of influenza virus [31] .