Pituitary Hollow Fiber Units in vivo and in vitro

Abstract

A new technique is described for the study of mammalian pituitary cells in vivo and in vitro. The method involves encapsulation of freshly trypsinized rat, sheep or human pituitary cells in XM-50 Amicon hollow fibers followed by their intracranial implantation into hypophysectomized rats. These pituitary fiber units promoted recipient growth for ∼3 weeks before weight gains plateaued. Body composition analyses showed that significant quantities of protein, fat and ash accounted for the weight gain. Morphological study of the capsule contents 7–39 days postimplantation revealed the presence of intact somatotrophs and corticotrophs. The hollow fibers may provide an immunologically privileged site by virtue of the fact that the 50,000 dalton pores making up the lumen surface permit pituitary hormones to diffuse from the capsule, but theoretically do not permit immunoglobulin molecules to penetrate the capsule. Growth of hypox rats receiving capsules containing allogeneic rat pituitary cells, sheep cells or pieces of human postmortem pituitary support this concept. Furthermore, rats implanted with human PRL adenoma cells had detectable quantities of circulating hPRL 100 days post-implantation. It is suggested that the pituitary hollow fiber units function when they come in contact with a ventricular surface of a hypox animal. With these units, it will be possible to study function of the same group of pituitary cells in vitro and in vivo.