Use of glucose‐responsive material to regulate insulin release from constitutively secreting cells

Abstract

Genetically-engineered cells offer a solution to the cell availability problem in tissue engineering a pancreatic substitute for the treatment of insulin-dependent diabetes. These cells can be non-beta cells, such as hepatocytes or myoblasts, retrieved as a biopsy from the same patient and genetically engineered to secrete recombinant insulin constitutively or under transcriptional regulation. However, the continuous or slowly responsive insulin secretion dynamics from these cells cannot provide physiologic glucose regulation in patients. Our objective consists of using such cells as an insulin source and of regulating insulin release by incorporating a glucose-responsive material, which acts as a control barrier for insulin in a cell-material hybrid device. Experiments were performed with insulinoma betaTC3 cells, HepG2 hepatomas, and C2C12 myoblasts, the latter two genetically-modified to constitutively secrete insulin. The control barrier consisted of concanavalin A (con A)-based glucose-responsive material, which forms a gel at low and a sol at high glucose concentrations. Results demonstrated that the device released insulin at a higher rate in response to glucose challenges. In contrast, a device containing an inert hydrogel instead of glucose-responsive material released insulin at an essentially constant rate, irrespective of the surrounding glucose concentration. Necessary material improvements include increased sensitivity to glucose, so that the material responds to physiologically relevant glucose concentrations, and increased stability. The prospects of developing a properly functional, implantable substitute based on engineered non-beta cells and glucose-responsive material, and the material and device improvements that need to be made prior to in vivo experiments, are discussed.

Injectable in situ forming glucose‐responsive dextran‐based hydrogels to deliver adipogenic factor for adipose tissue engineering

“…As ConA was progressively dissociated from the gel on adding glucose, the cross‐linking density decreased and the gel swelled. Competitive displacement results in temporarily lowering of the swelling of the hydrogel, which would trigger swelling in hydrogel and consequently facilitating the release of insulin by diffusion‐mediated process 34, 35…”

“…This displacement causes a fall in viscosity within the gel network and allows a greater flux of insulin. Recently, several groups have developed reversible glucose‐sensitive hydrogels based on ConA entrapment or covalently immobilization within the poly(ethylene glycol), polyacrylic acid, glycogen, dextran, and polysucrose gels 32–37. These systems showed a differential delivery of insulin in response to glucose with in vitro diffusion experiments.…”

Cryopreservation effects on recombinant myoblasts encapsulated in adhesive alginate hydrogels

“…Stable C2C12 cells were previously prepared by transfection with a furin-cleavable, B10-modified human insulin gene expressed downstream of a CMV promoter and by selection with puromycin [46]. Stable C2C12 cells were cultured in 25 mM glucose Dulbecco’s Modified Eagle’s Medium (DMEM, Mediatech, Manassas, VA) supplemented with 10% Fetal Bovine Serum (FBS, Gemini Bioproducts, West Sacramento, CA), 1% penicillin/streptomycin (P/S, Mediatech) and 1 μg/ml puromycin (Sigma) in order to maintain constant selective pressure on the cells.…”

The Complementarity of the Technical Tools of Tissue Engineering and the Concepts of Artificial Organs for the Design of Functional Bioartificial Tissues

“…It is interesting to mention that because of the lack of appropriate concepts and methodologies, tissue engineering applies the artificial organ methodology to implement tissue functions in bioartificial tissues. In a recent study, a hybrid scaffold‐cell device has been developed implementing the function of the controlled insulin release with a totally artificial instead of bioartificial design (15). A glucose‐responsive material scaffold that formed a gel at low and a sol at high glucose concentrations allowed the regulation of the insulin release from the device according to the surrounding glucose concentration.…”