Islet- and stem-cell-based tissue engineering in diabetes

Biomaterial-mediated strategies for accurate and convenient diagnosis, and effective treatment of diabetes: advantages, current progress and future perspectives

As a kind of widespread chronic disease, diabetes potentially triggers serious complications, thereby severely threatening patients' life and health. To achieve the goal of more accurate and convenient diagnosis, and effective treatment of diabetes that what could be achieved based on traditional methods, many biomaterial-mediated strategies have been launched in recent studies, and have shown promising application potentials. In this review, we have systematically summarized the biomaterial-mediated diagnosis strategies in three parts including combined use of biomedical nanomaterials or organometallic compounds and Raman spectroscopy, utilization of gas sensors made of biomedical metal-oxides to detect glucose in exhaled gas, and detection of glucose by wearable sensors made of biomaterials with high sensitivity and conductivity, and the biomaterial-mediated treatment strategies in four parts including antidiabetic drug delivery by nanoparticles, transdermal drug delivery systems, gels and vesicles, and achieving insulin secretion by transplantation of pancreatic endocrine cells or tissue engineered islets. In particular, advantages of every strategy, current research progress, as well as the challenges and perspectives are elaborated. This review will certainly help to spark new ideas and possibilities for accurate and convenient diagnosis, and effective treatment of diabetes.

Cell Encapsulation and 3D Bioprinting for Therapeutic Cell Transplantation

The promise of cell therapy has been augmented by introducing biomaterials, where intricate scaffold shapes are fabricated to accommodate the cells within. In this review, we first discuss cell encapsulation and the promising potential of biomaterials to overcome challenges associated with cell therapy, particularly cellular function and longevity. More specifically, cell therapies in the context of autoimmune disorders, neurodegenerative diseases, and cancer are reviewed from the perspectives of preclinical findings as well as available clinical data. Next, techniques to fabricate cell-biomaterials constructs, focusing on emerging 3D bioprinting technologies, will be reviewed. 3D bioprinting is an advancing field that enables fabricating complex, interconnected, and consistent cell-based constructs capable of scaling up highly reproducible cell-biomaterials platforms with high precision. It is expected that 3D bioprinting devices will expand and become more precise, scalable, and appropriate for clinical manufacturing. Rather than one printer fits all, seeing more application-specific printer types, such as a bioprinter for bone tissue fabrication, which would be different from a bioprinter for skin tissue fabrication, is anticipated in the future.

Mechanical stretch promotes antioxidant responses and cardiomyogenic differentiation in P19 cells

Accumulating evidence has suggested that mechanical stimuli play a crucial role in regulating the lineage-specific differentiation of stem cells through fine-tuning redox balance. We aimed to investigate the effects of cyclic tensile strain (CTS) on the expression of antioxidant enzymes and cardiac-specific genes in P19 cells, a widely characterized tool for cardiac differentiation research. A stretching device was applied to generate different magnitude and duration of cyclic strains on P19 cells. The messenger RNA and protein levels of targeted genes were determined by real-time polymerase chain reaction and Western blot assays, respectively. Proper magnitude and duration of cognitive stimulation therapy (CST) stimulation substantially enhanced the expression of both antioxidant enzymes and cardiac-specific genes in P19 cells. Sirtuin 1 (SIRT1) played an essential role in the CTS-induced cardiomyogenic differentiation of P19, as evidenced by changes in the expression of antioxidant enzymes and cardiac-specific genes. Mechanical loading promoted the cardiomyogenic differentiation of P19 cells. SIRT1 was involved in CST-mediated P19 differentiation, implying that SIRT1 might serve as an important target for developing methods to promote cardiomyogenic differentiation of stem cells.

Review of Advanced Hydrogel-Based Cell Encapsulation Systems for Insulin Delivery in Type 1 Diabetes Mellitus

: Type 1 Diabetes Mellitus (T1DM) is characterized by the autoimmune destruction of β-cells in the pancreatic islets. In this regard, islet transplantation aims for the replacement of the damaged β-cells through minimally invasive surgical procedures, thereby being the most suitable strategy to cure T1DM. Unfortunately, this procedure still has limitations for its widespread clinical application, including the need for long-term immunosuppression, the lack of pancreas donors and the loss of a large percentage of islets after transplantation. To overcome the aforementioned issues, islets can be encapsulated within hydrogel-like biomaterials to diminish the loss of islets, to protect the islets resulting in a reduction or elimination of immunosuppression and to enable the use of other insulin-producing cell sources. This review aims to provide an update on the different hydrogel-based encapsulation strategies of insulin-producing cells, highlighting the advantages and drawbacks for a successful clinical application.

Polymeric Scaffolds for Pancreatic Tissue Engineering: A Review

In recent years, there has been an alarming increase in the incidence of diabetes, with one in every eleven individuals worldwide suffering from this debilitating disease. As the available treatment options fail to reduce disease progression, novel avenues such as the bioartificial pancreas are being given serious consideration. In the past decade, the research focus has shifted towards the field of tissue engineering, which helps to design biological substitutes for repair and replacement of non-functional or damaged organs. Scaffolds constitute an integral part of tissue engineering; they have been shown to mimic the native extracellular matrix, thereby supporting cell viability and proliferation. This review offers a novel compilation of the recent advances in polymeric scaffolds, which are used for pancreatic tissue engineering. Furthermore, in this article, the design strategies for bioartificial pancreatic constructs and their future applications in cell-based therapy are discussed.

Induction of Nestin Early Expression as a Hallmark for Mesenchymal Stem Cells Expression of PDX-1 as a Pre-disposing Factor for Their Conversion into Insulin Producing Cells

Diabetes constitutes a worldwide epidemic that affects all ethnic groups. Cell therapy is one of the best alternatives of treatment, by providing an effective way to regenerate insulin-producing cells lost during the course of the disease, but many issues remain to be solved. Several groups have been working in the development of a protocol capable of differentiating Mesenchymal Stem Cells (MSCs) into physiologically sound Insulin Producing Cells (IPCs). In order to obtain a simple, fast and direct method, we propose in this manuscript the induction of MSCs to express NESTIN in a short time period (2 h), proceeded by incubation in a low glucose induced medium (24 h) and lastly by incubation in a high glucose medium. Samples from cell cultures incubated in high glucose medium from 12 to 168 h were obtained to detect the expression of INSULIN-1, INSULIN -2, PDX-1 and GLUT-2 genes. Induced cells were exposed to a glucose challenge, in order to assess the production of insulin. This method allowed us to obtain cells expressing PDX-1, which resembles a progenitor insulin-producing cell.

5-Azacytidine delivered by mesoporous silica nanoparticles regulates the differentiation of P19 cells into cardiomyocytes

Heart disease is one of the deadliest diseases causing mortality due to the limited regenerative capability of highly differentiated cardiomyocytes. Stem cell-based therapy in tissue engineering is one of the most exciting and rapidly growing areas and raises promising prospects for cardiac repair. In this study, we have synthesized FITC-mesoporous silica nanoparticles (FMSNs) based on a sol-gel method (known as Stöber's method) as a drug delivery platform to transport 5-azacytidine in P19 embryonic carcinoma stem cells. The surfactant CTAB is utilized as a liquid crystal template to self-aggregate into micelles, resulting in the synthesis of MSNs. Based on the cell viability assay, treatment with FMSNs + 5-azacytidine resulted in much more significant inhibition of the proliferation than 5-azacytidine alone. To study the mechanism, we have tested the differentiation genes and cardiac marker genes in P19 cells and found that these genes have been up-regulated in P19 embryonic carcinoma stem cells treated with FMSNs + 5-azacytidine + poly(allylamine hydrochloride) (PAH), with the changes of histone modifications on the regulatory region. In conclusion, with FMSNs as drug delivery platforms, 5-azacytidine can be more efficiently delivered into stem cells and can be used to monitor and track the transfection process in situ to clarify their effects on stem cell functions and the differentiation process, which can serve as a promising tool in tissue engineering and other biomedical fields.

Human Bone Marrow Subpopulations Sustain Human Islet Function and Viability In vitro

AIMS

Allogeneic bone marrow (BM) has been shown to support human islet survival and function in long-term culture by initiating human islet vascularization and β-cell regeneration. Various BM subpopulations may play different roles in human islet functions and survival. In this paper we investigated the effects of BM and its subpopulations, endothelial progenitor cells (E) and mesenchymal (M) cells on human islet's β-cell function and regeneration.

STUDY DESIGN

Isolation and identification of subpopulations from human bone marrow and culture with allogeneic human islet to investigate effects of different cell population on human islet function and regeneration.

PLACE AND DURATION OF STUDY

Department of Medicine, Center for Stem Cell & Diabetes Research, RWMC, Providence, RI, USA, between 2010 - 2014.

METHODOLOGY

Human islets were distributed from Integrated Islet Distribution Program (IIDP) and human bone marrow (BM) was harvested by Bone marrow transplantation center at Roger Williams Hospital. BM subpopulation was identified cell surface markers through Fluorescence-activated cell sorting, applied in flow cytometry (FACS), islet function was evaluated by human ELISA kit and β cell regeneration was evaluated by three methods of Cre-Loxp cell tracing, β cell sorting and RT-PCR for gene expression.

RESULTS

Four different BM and seven different islet donates contributed human tissues. We observed islet β-cell having self regeneration capability in short term culture (3∼5 days) using a Cre-Loxp cell tracing. BM and its subtype E, M have similar benefits on β cell function during co-culture with human islet comparison to islet only. However, only whole BM enables to sustain the capability of islet β-cell self regeneration resulting in increasing β cell population while single E and M individual do not significantly affect on that. Mechanism approach to explore β-cell self regeneration by evaluating transcription factor expressions, we found that BM significantly increases the activations of β-cell regeneration relative transcription factors, the LIM homeodomain protein (Isl1), homologue to zebrafish somite MAF1 (MAFa), the NK-homeodomain factor 6.1 (NKX6.1), the paired box family factors 6 (PAX6), insulin promoter factor 1 (IPF1) and kinesin family member 4A (KIF4a).

CONCLUSION

These results suggest that BM and its derived M and E cells enable to support human islet β-cell function. However, only BM can sustain the capability of β-cell self regeneration through initiating β-cell transcriptional factors but not individual E and M cells suggesting pure E and M cells less supportive for islet long-term survival in vitro.

Engineering β-cell islets or islet-like structures for type 1 diabetes treatment

Type 1 diabetes mellitus is a disease characterized by the destruction of the β-cells in the pancreatic islets of Langerhans. The current primary treatment for type 1 diabetes is insulin injections administered multiple times throughout the day. However, this treatment cannot provide sustained physiological release of insulin and the insulin amount is not finely tuned to the glycemia condition. Pancreatic transplantation or islet transplantation would be the preferred treatment strategy but the lack of donor tissue and immunoincompatibility has been shown to be a roadblock to their widespread use. Bioengineering strategies are poised to combat these challenges. Islet encapsulation is expected to offer both immunoisolation and immunomodulation effects by: (1) physically protecting islets from the attacks of immunoglobulins, complements, and host immune cells, and (2) delivering immune regulatory and immunomodulatory factors locally to the islets to protect those islets from immune rejection. Semi-permeable coatings using biocompatible biomaterials can be used for immunoisolating islets away from the host immune systems. Immunoisolation technology also provides an opportunity to use other cell sources for cell therapy to treat type 1 diabetes. Recently, some studies reported that co-transplantation of islets with mesenchymal stem cells (MSCs) can control graft inflammation. MSCs have immunomodulatory property. They are able to secrete anti-inflammatory factors and repress the activity of various immune cells. Growth factors like interleukin 10 (IL-10) and leukemia inhibitory factor (LIF) also have immune regulatory properties. Therefore immunoisolation and immunomodulation technologies can be integrated and applied to β-cell encapsulation for the treatment of type 1 diabetes. Through engineering β-cell islets or islet-like microtissues, the viability and function of transplanted β-cells may be improved. In the meantime, the survival of transplanted β-cells can be further improved by promoting vascular network formation surrounding the transplanted islets or microtissues.

A comparative study of mesenchymal stem cell transplantation with its paracrine effect on control of hyperglycemia in type 1 diabetic rats

Background

Many studies suggested mesenchymal stem cells (MSCs) transplantation as a new approach to control hyperglycemia in type 1 diabetes mellitus through differentiation mechanism. In contrary others believed that therapeutic properties of MSCs is depends on paracrine mechanisms even if they were not engrafted. This study aimed to compare these two approaches in control of hyperglycemia in STZ-induced diabetic rats.

Methods

Animals were divided into five groups: normal; diabetic control; diabetic received MSCs; diabetic received supernatant of MSCs; diabetic received co-administration of MSCs with supernatant. Blood glucose, insulin levels and body weight of animals were monitored during experiment. Immunohistochemical and immunofluorescence analysis were performed to monitor functionality and migration of labeled-MSCs to pancreas.

Results

First administration of MSCs within the first 3 weeks could not reduce blood glucose, but second administration significantly reduced blood glucose after week four compared to diabetic controls. Daily injection of supernatant could not reduce blood glucose as efficient as MSCs. Interestingly; Co-administration of MSCs with supernatant significantly reduced blood glucose more than other treated groups. Insulin levels and body weight were significantly increased in MSCs + supernatant-treated animals compared to other groups. Immunohistological analysis showed an increase in number and size of islets per section respectively in supernatant, MSCs and MSCs + supernatant-treated groups.

Conclusion

Present study exhibited that repeated-injection of MSCs reduced blood glucose and increased serum insulin levels in recipient rats. Injection of supernatant could not reverse hyperglycemia as efficient as MSCs. Interestingly; co-administration of MSCs with supernatant could reverse hyperglycemia more than either group alone.

Gastrin treatment stimulates β-cell regeneration and improves glucose tolerance in 95% pancreatectomized rats

β-Cell mass reduction is a central aspect in the development of type 1 and type 2 diabetes, and substitution or regeneration of the lost β-cells is a potentially curative treatment of diabetes. To study the effects of gastrin on β-cell mass in rats with 95% pancreatectomy (95%-Px), a model of pancreatic regeneration, rats underwent 95% Px or sham Px and were treated with [15 leu] gastrin-17 (Px+G and S+G) or vehicle (Px+V and S+V) for 15 d. In 95% Px rats, gastrin treatment reduced hyperglycemia (280 ± 52 mg vs. 436 ± 51 mg/dl, P < 0.05), and increased β-cell mass (1.15 ± 0.15 mg)) compared with vehicle-treated rats (0.67 ± 0.15 mg, P < 0.05). Gastrin treatment induced β-cell regeneration by enhancing β-cell neogenesis (increased number of extraislet β-cells in Px+G: 0.42 ± 0.05 cells/mm(2) vs. Px+V: 0.27 ± 0.07 cells/mm(2), P < 0.05, and pancreatic and duodenal homeobox 1 expression in ductal cells of Px+G: 1.21 ± 0.38% vs. Px+V: 0.23 ± 0.10%, P < 0.05) and replication (Px+G: 1.65 ± 0.26% vs. S+V: 0.64 ± 0.14%; P < 0.05). In addition, reduced β-cell apoptosis contributed to the increased β-cell mass in gastrin-treated rats (Px+G: 0.07 ± 0.02%, Px+V: 0.23 ± 0.05%; P < 0.05). Gastrin action on β-cell regeneration and survival increased β-cell mass and improved glucose tolerance in 95% Px rats, supporting a potential role of gastrin in the treatment of diabetes.

The effects of cell density and device arrangement on the behavior of macroencapsulated beta-cells

Over the last several decades, considerable research has focused on the development of cell encapsulation technology to treat a number of diseases, especially type 1 diabetes. One of the key advantages of cell encapsulation is that it permits the use of xenogenic tissue, particularly animal-derived cell lines. This is an attractive idea, because it circumvents the issue of a limited human organ supply. Furthermore, as opposed to whole islets, cell lines have a better proliferative capacity and can easily be amplified in culture to provide an endless supply of uniform cells. We have previously described a macroencapsulation device for the immunoisolation of insulin-secreting 1-cells. The aim of this work was to optimize the viability and insulin secretion of cells encapsulated within this device. Specifically, the effects of cell packing density and device membrane configuration were investigated. The results indicated that cell density plays an important role in the secretory capacity of the cells, with higher cell density leading to increased insulin secretion. Increasing the transport area of the capsule by modifying the membrane configuration also led to an improvement in the insulin output of the device.

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