Encapsulated beta-islet cells as a bioartificial pancreas to treat insulin-dependent diabetes during pregnancy

The status of diabetic embryopathy

Diabetic embryopathy is a theoretical enigma and a clinical challenge. Both type 1 and type 2 diabetic pregnancy carry a significant risk for fetal maldevelopment, and the precise reasons for the diabetes-induced teratogenicity are not clearly identified. The experimental work in this field has revealed a partial, however complex, answer to the teratological question, and we will review some of the latest suggestions.

Cell encapsulation as a potential nondietary therapy for maternal phenylketonuria

OBJECTIVE

The objective of this work was to determine whether cells overexpressing phenylalanine (Phe) hydroxylase (PAH) can significantly reduce Phe in vitro for potential use as a therapy for preventing maternal phenylketonuria.

STUDY DESIGN

Human 293T and WRL68 cell lines were transiently and stably transfected to overexpress PAH. Cells were encapsulated within microspheres of sodium alginate. Timed measurements of Phe in media were performed using tandem mass spectrometry.

RESULTS

Both nonencapsulated and encapsulated transiently transfected cells overexpressing PAH significantly reduced the Phe concentration in media by approximately 50% in comparison to mock-transfected cells. Cell line clones stably expressing PAH significantly decreased the Phe concentration in the media by up to 85% compared with media alone.

CONCLUSION

Both unencapsulated and encapsulated cells overexpressing PAH significantly reduce Phe in vitro. Studies using phenylketonuria model mice will be important in determining the ability of our therapy to prevent the teratogenic effects of elevated maternal Phe in maternal phenylketonuria.

The role of a bioengineered artificial kidney in renal failure

Renal failure continues to carry substantial burden of morbidity and mortality in both acute and chronic forms, despite advances in transplantation and dialysis. There is evidence to suggest that the kidney has metabolic, endocrine, and immune effects transcending its filtration functions, even beyond secretion of renin and erythropoietin. Our laboratory has developed experience in the tissue culture of renal parenchymal cells, and has now been able to demonstrate the metabolic activity of these cells in an extracorporeal circuit recapitulating glomerulotubular anatomy. We have observed active transport of sodium, glucose, and glutathione. We describe the design and initial preclinical testing of the bioartificial kidney, as well as future directions of our research.

Present and future perspectives on the use of free or encapsulated pancreatic islet cell transplantation as a treatment of pregnancy complicated by type 1 diabetes

Pregnancies complicated by insulin-dependent diabetes mellitus (IDDM) pose significant health risks to both the mother and her developing fetus. Congenital malformations in the offspring of diabetic mothers have an incidence which is 2-5 times that seen in the background. Euglycemia in the first trimester of pregnancy can reduce this incidence, but achieving euglycemia with conventional exogenous insulin therapy is both costly and difficult. Even with intense insulin dosage adjustments, the blood glucose profile of the diabetic pregnant patient does not mimic that seen in nondiabetic patients. Both the difficulties and inadequacies of conventional therapy for IDDM-complicated pregnancy provide a stimulus for research to develop improved therapeutic modalities. Islet transplantation holds great promise as a treatment for pregnancies complicated by IDDM. This article reviews the current status of islet transplantation including the use of immunomodulation and immunoisolation techniques and their potential use for the treatment of IDDM pregnancies.

Pathogenesis of diabetes-induced congenital malformations

The increased rate of fetal malformation in diabetic pregnancy represents both a clinical problem and a research challenge. In recent years, experimental and clinical studies have given insight into the teratological mechanisms and generated suggestions for improved future treatment regimens. The teratological role of disturbances in the metabolism of inositol, prostaglandins, and reactive oxygen species has been particularly highlighted, and the beneficial effect of dietary addition of inositol, arachidonic acid and antioxidants has been elucidated in experimental work. Changes in gene expression and induction of apoptosis in embryos exposed to a diabetic environment have been investigated and assigned roles in the teratogenic processes. The diabetic environment appears to simultaneously induce alterations in several interrelated teratological pathways. The complex pathogenesis of diabetic embryopathy has started to unravel, and future research efforts will utilize both clinical intervention studies and experimental work that aim to characterize the human applicability and the cell biological components of the discovered teratological mechanisms.