MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente
Extrahepatic islet transplantation using bioengineered advanced microfabricated thin-film macroporous microwell scaffolds leads to rapid recovery of normoglycemia in diabetic mice
Mijke Buitinga1, Frank Assen1, Paul Wieringa2, Janneke Hilderink1, Lorenzo Moroni2, Peter Buchwald5, Roman Truckenmüller2, Gert-Willem Römer1, Françoise Carlotti4, Eelco JP de Koning4, Marcel Karperien1, Aart van Apeldoorn1.
1Developmental Bioengineering, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, Netherlands; 2Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, Netherlands; 3Applied Laser Technology, University of Twente, Enschede, Netherlands; 4Nephrology, Leiden University Medical Centre, Leiden, Netherlands; 5Diabetes Research Institute, University of Miami, Miami, FL, United States
Although outcomes of clinical islet transplantation (CIT) have improved since its implementation, gradual loss of endocrine function in the post-transplantation period still prevents long-term insulin independence. CIT is affected by mechanical stress, high drug or toxin loads, and an immediate blood mediated inflammatory reaction, causing a 60% loss of islets directly after transplantation, and a progressive loss of endocrine function in the longterm due to a suboptimal intrahepatic environment. By transplanting islets extrahepatically these negative factors can be averted resulting potentially in better clinical outcome. Pancreatic islets are innervated by a dense network of microvessels, vital for an adequate nutrient and oxygen supply, accurate glucose sensing, and efficient secretion of islet hormones into the blood. Islet biology dictates that an islet tissue engineered construct should allow for high mass transport and rapid revascularization. The use of specifically tailored macroporous bioengineered scaffolds for extrahepatic islet transplantation can help reduce the aforementioned disadvantages by providing an optimal microenvironment for islets.
By combining advanced microfabrication techniques and high-resolution pulsed laser drilling we made thin-film microwells arrays of a non-degradable biomaterial comprising a poly(ethyleneglycol)terephthalate-poly(butylene)terephthalate block copolymer. Femtosecond pulsed laser drilling was used to create a regular pattern of pores, Ø 40 μm, in thin-film, 500 μm thick, scaffolds containing a dense array of evenly distributed microwells. Each microwell is able to hold one individual islet thus preventing islet aggregation and providing biomechanical protection.
After optimization of the microfabrication method we seeded a marginal mass of 300IEQ into these scaffolds followed by implantation into the epididymal fat pad of diabetic BALBc mice for a month. During implantation blood glucose levels were compared over time with mice treated with a similar amount of free islets transplanted at the same location, and mice with islets under the kidney capsule. We performed intraperitoneal glucose tolerance tests (IPGTT) at day 14 and 28 to test glucose responsiveness and after the transplant period vascular ingrowth and changes in β- and α-cell composition were systematically quantified using immunofluorescent microscopy.
In the scaffold group 6 of 8 mice recovered from type 1 diabetes, becoming normoglycemic within 2 days after transplantation, in contrast to the non-scaffold group (2 of 8). IPGTT revealed that the glucose responsiveness of the scaffold group was similar to the positive kidney control group at 28 days. The time to euglycemia for the non-scaffold group was significantly longer compared to the kidney control group (p<0.01). Pairwise comparison between the kidney and scaffold group did not reveal a significant difference (p=0.068)
Microscopy revealed that islets remained confined in their respective microwells, while numerous bloodvessels were observed growing via the macropores into the islets. Subsequent immunofluorescent analysis revealed that revascularization of islets occurs from the outside-in, via the pores, and that the islet cellular composition followed this trend in regard to β-cell density showing an anisotropic beta-cell distribution, with the highest density in the outer shell of each islet gradually declining inwards similar to the vessel density.
Dutch Fund for Economic Reinforcement (FES). Dutch Diabetes Research Fund (DCTI consortium).
11:00 - 12:30
|Alternative Sources of Beta Cells: Xenoislet, Stem Cells, Tissue Engineering||Extrahepatic islet transplantation using bioengineered advanced microfabricated thin-film macroporous microwell scaffolds leads to rapid recovery of normoglycemia in diabetic mice||Room 110|
11:00 - 12:30
|Tissue Engineering and Stem Cell Differentiation||Controlled reassembly of human donor islet cells into well-defined organoids results in glucose-responsive and functional pseudoislets in vitro, capable of c-peptide production in a mouse kidney capsule transplant model||Room 111-112|
11:00 - 12:30
|Tissue Engineering and Stem Cell Differentiation||Preconditioned hMSCs and HUVECs boost revasularisation of human islets in a subcutaneous transplantation site||Room 111-112|