Microencapsulation of Parathyroid Cells for the Treatment of Hypoparathyroidism.

Cell encapsulation is an alternative to avoid rejection of grafted tissue, thus bringing an interesting alternative in cell therapy. It is particularly relevant in ailments where only the implant of small quantities of tissues is warranted. In such circumstances, the use of immunosuppressive therapy in patients implanted with tissues from donors is debatable, yet unavoidable at present in order to prevent rejection and/or sensitization of the host to the tissue, in turn jeopardizing the success of successive implants. Hence, a new line of thought, which aims to provide an immunoprivileged site for the grafted tissue, while at the same time insure its nutrition, as well as its survival and continued function, appears as a most attractive possibility. To achieve these goals, cells or tissues harvested for transplant could be encapsulated in biologically compatible matrices. Among the matrices currently in existence, sodium alginate is the most widely used polymer for tissue encapsulation.In the present chapter, we present a technique used to encapsulate parathyroid tissue, for use as cell transplant therapy in patients with secondary hypoparathyroidism. With this procedure, implanted tissue survives and remains functional for up to 18 months.

Pancreatic autotransplantation in chronic pancreatitis.

The apancreatic state secondary to resective surgery for chronic pancreatitis is associated with a high rate of late morbidity and mortality that is due, in part, to endocrine insufficiency. Resective procedures should, therefore, be used very selectively. Over the last 2 decades we have seen a shift from extensive distal resections to limited proximal resections. This is because of the lowering of the operative mortality of pancreatic head resection and its better results in pain relief, while preserving in situ the body and tail of the gland with its metabolic functions. Islet autotransplantation and segmental pancreatic autotransplantation were introduced in 1977 and 1978, respectively. Over 150 and 25 cases of these operations have been reported, respectively. Both techniques are evolving with a goal to improve results. Procedures placing the graft in the iliac fossa and anastomosing the pancreatic duct to the jejunum are now favored over groin placement and duct occlusion. Islet autotransplants achieve a higher yield of islet cells and decrease the exocrine impurity of the preparation. Both methods can prevent or delay the onset of diabetes mellitus, and when diabetes mellitus does occur, it is frequently easier to manage. The long-term function of the grafts appears to be dependent on the beta-cell mass available in the diseased pancreas, the loss of cells related to the transplant procedure, and the characteristics of gradual loss of function from the type of transplant used. Although extensive pancreatic resections are occasionally required, the possibility of autotransplantation should be considered in those patients.