Micropatterned Substrate for the Cultivation of Glucose-Responsive Tissue Engineered Islet for Diabetic Research and Cell Therapy

Diabetes Mellitus is a chronic, endocrine disease characterized by hyperglycaemia. In order to study the pathological processes, therapeutic regimens, and cell therapy to diabetes, fresh islets are required. Whole pancreas obtained from a cadaver is rare, and thus islets isolated from animals (mainly rats and mice) are widely used. However, isolated islets cannot survive more than one week in vitro. Because of the limitation of isolation technology, large numbers of animals are required for islet isolation. All these issues limit the progresses of diabetic researches. In spite of animal experiments are widely used in pharmaceutical developments and biomedical researches, there is a widespread agreement in the reduction of numbers and to find alternatives to lab animals. Recently, tissue engineered 3D microtissue and organoid are proposed to replace lab animals. Several studies also tried to culture pancreatic beta- (P-)cells as spheroids so called as pseudoislets for diabetic researches. However, native islets are mainly composed of alpha- (a-), P-, and delta-(S)-cells with unique cytoarchitecture. These three types of cells have complex interactions and cell coupling to regulate insulin secretion. Therefore, P-cell pseudoislets cannot represent the reality native islets. In this project, tissue-engineered approach will be used and the micropatterned substrate will be developed to culture the glucose-responsive tissue-engineered islets which composed of a-, P-, and 5-cells. First Year The tissue-engineered islets will be formed using micropatterned substrates with different surface modifications. Pancreatic a-, P- and 5-cell will be cultured at different cell rations for various intervals. The size, number, proliferation, survival, activity, apoptosis, cell distribution, junctional protein (gap junction protein connexin, Cx; and tight junction protein zona occludens 1, ZO-1), and insulin secretion will be analyzed. Second Year The mRNA expressions, biological properties and functions of the tissue-engineered islets will be determined. A perifusion system will be established to test the responses of tissue-engineered islets to glucose stimulation. RNA interference (RNAi) will be used to knockdown the cell coupling to study the communication/interaction among cells. Third Year The tissue-engineered islets will be embedded in matrix (with pancreatic acinar cells within hydrogels) to fabricate a bioartificial pancreas. Insulin-related gene expressions, insulin and glucagon secretion, and digestive enzymes productions will be evaluated in the bioartificial pancreas. A diabetic rat model will be established to test the in vivo regulation of the bioartificial pancreas to blood glucose levels. The purpose of this project is to develop glucose-responsive tissue-engineered islets which composed of a-, P-, and 5-cells. The tissue-engineered islets may serve as alternatives to experimental animals in the fields of diabetic researches, drug screening, ex vivo model, and other biomedical studies. In addition, the bioartificial pancreas may also been used in cell therapy for diabetic animals. We expect these tissue-engineered islets can improve diabetic researches and promote biomedical developments.