Research Project: İnsülin Salgılayan Kemirici Pankreatik beta-hücrelerinin (Min-6) Kök Hücre İçeren İşlevsel PEG Sujeli ile Kaplanması
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Contributors
Funders
ID
TB.00143
Authors
Kızılel, Seda
Faculty Member
Publications
Mesenchymal stem cells and ligand incorporation in biomimetic poly(ethylene glycol) hydrogels significantly improve insulin secretion from pancreatic islets
(Wiley, 2017) Bal, Tuğba; Kızılel, Seda; Nazlı, Caner; Okçu, Alparslan; Duruksu, Gökhan; Karaöz, Erdal; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING
The main goal of this study was to investigate pancreatic islet function with mesenchymal stem cells (MSCs) in a ligand-functionalized poly(ethylene glycol) (PEG) hydrogel for the treatment of type 1 diabetes (T1D). Rat bone marrow-derived MSCs (rBM-MSCs) were encapsulated within synthetic PEG hydrogel, and cell viability and apoptosis within this 3D environment was examined in detail. ATP content and caspase-3 activity of encapsulated MSCs showed that fibronectin-derived RGDS, laminin-derived IKVAV and/or insulinotropic glucagon-like peptide (GLP-1) were required to maintain MSC survival. Incorporation of these peptides into the hydrogel environment also improved pancreatic islet viability, where combinations of peptides had altered effects on islet survival. GLP-1 alone was the leading stimulator for insulin secretion. Cell adhesion peptides RGDS and IKVAV improved insulin secretion only when theywere used in combination, but could not surpass the effect of GLP-1.Further, when pancreatic islets were co-encapsulated with MSCs within synthetic PEG hydrogel, a two- fold increase in the stimulation index wasmeasured. Synergistic effects ofMSCs and peptideswere observed, with a seven-fold increase in the stimulation index. The results are promising and suggest that simultaneous incorporation ofMSCs and ECM-derived peptides and/or GLP-1 can improve pancreatic islet function in response to altered glucose levels in the physiological environment.
Sensitivity study for the key parameters in heterospheroid preparation with insulin-secreting beta-cells and mesenchymal stem cells
(American Chemical Society (ACS), 2019) Bal, Tuğba; İnceoğlu, Yasemin; Kızılel, Seda; Karaöz, Erdal; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING
The outcome of islet transplantation in clinics has been determined by the success of tissue engraftment. The strong immune attack that occurs upon transplantation of beta-cells plays a central role as this attack results in the failure of transplanted tissue. To improve tissue engraftment, deleterious effects of immune reactions should be minimized for Pull function and survival. Here, we report a systematic analysis of the effect of insulin-secreting beta-cell (MIN6) and mesenchymal stem cell (MSC) number and size on the function of beta-cells and present immune protection potential of heterospheroid structures through MSCs and synthetic scaffolds. We prepared 3D heterospheroids with MSCs and MIN6 cells through a hanging-drop approach. To precisely estimate the influence of critical parameters on heterospheroid size and insulin secretion function of beta-cells, we prepared heterospheroids using two independent input variables: (i) initial cell number in each droplet and (ii) MIN6:MSC ratio. We studied the influence of initial cell numbers of 200 and 500, and six different MIN6:MSC ratios (1:0, 0:1, 1:1, 2:1, 5:1, and 10:1) for the preparation of heterospheroids through the hanging drop. Next, we used PEG hydrogels as a semipermeable physical barrier to improve immune protection from cytokines. Through encapsulation of our heterospheroids within PEG hydrogel, we were able to observe sustained beta-cell survival and insulin secretion despite exposure of heterospheroids with proinflammatory cytokines. Insulin secretion was further promoted with glucagon like peptide-1 (GLP-1) incorporation within PEG hydrogel structure. This study is significant to demonstrate the synergistic effects of MIN6-MSC and scaffold-MIN6 interactions and to improve therapeutic efficacy of islet transplantation. Overall, this study comprehensively presents the optimum conditions for the preparation of MIN6-MSC spheroids, utilizes MSCs and GLP-1 functional PEG hydrogels as a scaffold to retain insulin secretion function and further demonstrates protection of heterospheroids exposed to proinflammatory cytokines.
Sequential coating of insulin secreting beta cells within multilayers of polysaccharide nanogels
(Wiley, 2018) Bal, Tuğba; Kızılel, Seda; Oran, Dilem Ceren; Sasaki, Yoshihiro; Akiyoshi, Kazunari; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING
Pancreatic islet transplantation has emerged as a promising treatment for type-1 diabetes (T1D); however, its clinical application is still limited by the life-long use of immunosuppressive drugs, insufficient number of islets to achieve normoglycemia, and large transplantation volume. This paper reports a unique approach for nanothin coating of insulin secreting beta cell aggregates. The coating is based on hydrophobic and covalent interactions between natural acrylate modified cholesterol bearing pullulan (CHPOA) nanogels and MIN6 beta cell aggregates. Beta cell aggregates are prepared as spheroids through hanging drop method, which is optimized with respect to hanging drop volume and initial number of beta cells. These aggregates, defined as pseudoislets, are coated with sequential layers of nanogels and are evaluated as viable and functional for insulin secretion. Coating experiments are carried out using physiologically compatible medium, where pseudoislets are not brought in contact with toxic prepolymer solutions used in existing approaches. This study offers new opportunities through coating of islets with advanced functional materials under completely physiological conditions for clinical translation of cell transplantation technology. The technique developed here will establish a new paradigm for creating tolerable grafts for other chronic diseases such as anemia, cancer, central nervous system (CNS) diseases.
Immunological response of polysaccharide nanogel-incorporating PEG hydrogels in an in vivo diabetic model
(Taylor and Francis, 2022) Bal, Tuğba; Karaoğlu, İsmail Can; Murat, Füsun Şevval; Yalçın, Esra; Kızılel, Seda; Sasaki, Yoshihiro; Akiyoshi, Kazunari; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING
Cell-based therapies hold significant advantages in comparison with the traditional drug-based or injection-based treatments. However, for long-term functional cellular implants, immune acceptance must be established. To accomplish the acceptance of the implanted cells, various biomaterial systems have been studied. Nanogels have shown great potential for modulation of cellular microenvironments, acting as a physical barrier between the immune system and the implant. However, internalization of nano-scale materials by implanted cells is not desirable and is yet to be overcome. In this study, we incorporated acrylate modified cholesterol-bearing pullulan (CHPOA) nanogels into poly (ethylene glycol) diacrylate (PEGDA) hydrogels through covalent crosslinking, where we used visible light-induced photopolymerization. We characterized morphology and swelling properties of CHPOA incorporated PEG composite hydrogels using FE-SEM and gravimetric analysis. Also, we investigated the biocompatibility properties of composite hydrogels in vivo, where we used both healthy and diabetic mice. We induced diabetes in mice using a low dose streptozotocin (STZ) injections and implanted composite hydrogels in both diabetic and healthy mice through subcutaneous route. Immune cell infiltration of the retrieved tissue was examined through histological analysis, where we observed minimum immune response levels of 0–2 rareness, according to ISO standard of biological evaluation of medical devices. Our observation suggests that the composite hydrogel developed here can be used to introduce nanostructured domains into bulk hydrogels and that this system has potential to be used as immunologically acceptable composite material in cellular therapy without internalization of nanoparticles.
