The mechanisms involved in islet neogenesis have remained largely unexplored due to lack of an appropriate model. Furthermore, with the recent advances in islet transplantation, the need for alternative islet tissue sources is greater than ever. Therefore, the authors have refined a neonatal porcine islet (NPI) maturation model that offers an ideal tool to gain insight into islet growth as well as an alternative source of transplantable tissue. Recent knowledge in islet growth has resulted in endocrine tissue being derived from human pancreatic precursor tissue in vitro. The potential for large scale production of endocrine tissue in vitro has been indicated, however, more investigation must be done on the various signals and pathways involved in pancreatic development to optimize this technique. The authors believe that their NPI in vitro maturation model provides an ideal tool to study islet growth and maturation. Transduction of the NPI to overexpress genes of interest (i.e., PDX-1) or exposure of the NPI to various culture conditions will allow us to determine the effects on islet maturation. An understanding of NPI development gained will not only allow us to mature this unlimited tissue source for optimal xenotransplantation, but also elude to how human pancreatic endocrine precursor cells may be used to solve the current islet tissue supply problem.