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Pareta R, McQuilling JP, Sittadjody S, Jenkins R, Bowden S, Orlando G, Farney AC, Brey EM, Opara EC. Long-term function of islets encapsulated in a redesigned alginate microcapsule construct in omentum pouches of immune-competent diabetic rats. Pancreas 2014; 43:605-13. [PMID: 24681880 PMCID: PMC3981909 DOI: 10.1097/mpa.0000000000000107] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Our study aim was to determine encapsulated islet graft viability in an omentum pouch and the effect of fibroblast growth factor 1 (FGF-1) released from our redesigned alginate microcapsules on the function of the graft. METHODS Isolated rat islets were encapsulated in an inner core made with 1.5% low-viscosity-high-mannuronic-acid alginate followed by an external layer made with 1.25% low-viscosity high-guluronic acid alginate with or without FGF-1, in microcapsules measuring 300 to 400 µm in diameter. The 2 alginate layers were separated by a perm-selective membrane made with 0.1% poly-L-ornithine, and the inner low-viscosity-high-mannuronic-acid core was partially chelated using 55 mM sodium citrate for 2 minutes. RESULTS A marginal mass of encapsulated islet allografts (∼2000 islets/kg) in streptozotocin-diabetic Lewis rats caused significant reduction in blood glucose levels similar to the effect observed with encapsulated islet isografts. Transplantation of alloislets coencapsulated with FGF-1 did not result in better glycemic control, but induced greater body weight maintenance in transplant recipients compared with those that received only alloislets. Histological examination of the retrieved tissue demonstrated morphologically and functionally intact islets in the microcapsules, with no signs of fibrosis. CONCLUSIONS We conclude that the omentum is a viable site for encapsulated islet transplantation.
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Affiliation(s)
- Rajesh Pareta
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - John P McQuilling
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
- Virginia Tech-Wake Forest University School of Biomedical Engineering & Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Sivanandane Sittadjody
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Randy Jenkins
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Stephen Bowden
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Giuseppe Orlando
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
- Department of Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Alan C Farney
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
- Department of Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Eric M Brey
- Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL, USA
- Research Service, Hines Veterans Administration Hospital, Hines, IL, USA
| | - Emmanuel C Opara
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
- Virginia Tech-Wake Forest University School of Biomedical Engineering & Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA
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Orive G, Santos E, Pedraz J, Hernández R. Application of cell encapsulation for controlled delivery of biological therapeutics. Adv Drug Deliv Rev 2014; 67-68:3-14. [PMID: 23886766 DOI: 10.1016/j.addr.2013.07.009] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 06/26/2013] [Accepted: 07/12/2013] [Indexed: 01/12/2023]
Abstract
Cell microencapsulation technology is likely to have an increasingly important role in new approaches rather than the classical and pioneering organ replacement. Apart from becoming a tool for protein and morphogen release and long-term drug delivery, it is becoming a new three-dimensional platform for stem cell research. Recent progress in the field has resulted in biodegradable scaffolds that are able to retain and release the cell content in different anatomical locations. Additional advances include the use biomimetic scaffolds that provide greater control over material-cell interactions and the development of more precise encapsulated cell-tracking systems. This review summarises the state of the art of cell microencapsulation and discusses the main directions and challenges of this field towards the controlled delivery of biological therapeutics.
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103
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Colton CK. Oxygen supply to encapsulated therapeutic cells. Adv Drug Deliv Rev 2014; 67-68:93-110. [PMID: 24582600 DOI: 10.1016/j.addr.2014.02.007] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 01/06/2014] [Accepted: 02/19/2014] [Indexed: 02/07/2023]
Abstract
Therapeutic cells encapsulated in immunobarrier devices have promise for treatment of a variety of human diseases without immunosuppression. The absence of sufficient oxygen supply to maintain viability and function of encapsulated tissue has been the most critical impediment to progress. Within the framework of oxygen supply limitations, we review the major issues related to development of these devices, primarily in the context of encapsulated islets of Langerhans for treating diabetes, including device designs and materials, supply of tissue, protection from immune rejection, and maintenance of cell viability and function. We describe various defensive measures investigated to enhance survival of transplanted tissue, and we review the diverse approaches to enhancement of oxygen transport to encapsulated tissue, including manipulation of diffusion distances and oxygen permeability of materials, induction of neovascularization with angiogenic factors and vascularizing membranes, and methods for increasing the oxygen concentration adjacent to encapsulated tissue so as to exceed that in the microvasculature. Recent developments, particularly in this latter area, suggest that the field is ready for clinical trials of encapsulated therapeutic cells to treat diabetes.
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Scharp DW, Marchetti P. Encapsulated islets for diabetes therapy: history, current progress, and critical issues requiring solution. Adv Drug Deliv Rev 2014; 67-68:35-73. [PMID: 23916992 DOI: 10.1016/j.addr.2013.07.018] [Citation(s) in RCA: 214] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/10/2013] [Accepted: 07/22/2013] [Indexed: 02/07/2023]
Abstract
Insulin therapy became a reality in 1921 dramatically saving lives of people with diabetes, but not protecting them from long-term complications. Clinically successful free islet implants began in 1989 but require life long immunosuppression. Several encapsulated islet approaches have been ongoing for over 30 years without defining a clinically relevant product. Macro-devices encapsulating islet mass in a single device have shown long-term success in large animals but human trials have been limited by critical challenges. Micro-capsules using alginate or similar hydrogels encapsulate individual islets with many hundreds of promising rodent results published, but a low incidence of successful translation to large animal and human results. Reduction of encapsulated islet mass for clinical transplantation is in progress. This review covers the status of both early and current studies including the presentation of corporate efforts involved. It concludes by defining the critical items requiring solution to enable a successful clinical diabetes therapy.
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105
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de Vos P, Lazarjani HA, Poncelet D, Faas MM. Polymers in cell encapsulation from an enveloped cell perspective. Adv Drug Deliv Rev 2014; 67-68:15-34. [PMID: 24270009 DOI: 10.1016/j.addr.2013.11.005] [Citation(s) in RCA: 186] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 08/26/2013] [Accepted: 11/13/2013] [Indexed: 02/07/2023]
Abstract
In the past two decades, many polymers have been proposed for producing immunoprotective capsules. Examples include the natural polymers alginate, agarose, chitosan, cellulose, collagen, and xanthan and synthetic polymers poly(ethylene glycol), polyvinyl alcohol, polyurethane, poly(ether-sulfone), polypropylene, sodium polystyrene sulfate, and polyacrylate poly(acrylonitrile-sodium methallylsulfonate). The biocompatibility of these polymers is discussed in terms of tissue responses in both the host and matrix to accommodate the functional survival of the cells. Cells should grow and function in the polymer network as adequately as in their natural environment. This is critical when therapeutic cells from scarce cadaveric donors are considered, such as pancreatic islets. Additionally, the cell mass in capsules is discussed from the perspective of emerging new insights into the release of so-called danger-associated molecular pattern molecules by clumps of necrotic therapeutic cells. We conclude that despite two decades of intensive research, drawing conclusions about which polymer is most adequate for clinical application is still difficult. This is because of the lack of documentation on critical information, such as the composition of the polymer, the presence or absence of confounding factors that induce immune responses, toxicity to enveloped cells, and the permeability of the polymer network. Only alginate has been studied extensively and currently qualifies for application. This review also discusses critical issues that are not directly related to polymers and are not discussed in the other reviews in this issue, such as the functional performance of encapsulated cells in vivo. Physiological endocrine responses may indeed not be expected because of the many barriers that the metabolites encounter when traveling from the blood stream to the enveloped cells and back to circulation. However, despite these diffusion barriers, many studies have shown optimal regulation, allowing us to conclude that encapsulated grafts do not always follow nature's course but are still a possible solution for many endocrine disorders for which the minute-to-minute regulation of metabolites is mandatory.
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McQuilling J, Pareta R, Sivanandane S, Khanna O, Jiang B, Brey E, Orlando G, Farney A, Opara E. Islet function within a multilayer microcapsule and efficacy of angiogenic protein delivery in an omentum pouch graft. BIOMATERIALS AND BIOMECHANICS IN BIOENGINEERING 2014. [DOI: 10.12989/bme.2014.1.1.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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O'Cearbhaill ED, Ng KS, Karp JM. Emerging medical devices for minimally invasive cell therapy. Mayo Clin Proc 2014; 89:259-73. [PMID: 24485137 DOI: 10.1016/j.mayocp.2013.10.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/22/2013] [Accepted: 10/24/2013] [Indexed: 12/13/2022]
Abstract
The past decade has seen the first wave of cell-based therapeutics undergo clinical trials with varying degrees of success. Although attention is increasingly focused on clinical trial design, owing to spiraling regulatory costs, tools used in delivering cells and sustaining the cells' viability and functions in vivo warrant careful scrutiny. While the clinical administration of cell-based therapeutics often requires additional safeguarding and targeted delivery compared with traditional therapeutics, there is significant opportunity for minimally invasive device-assisted cell therapy to provide the physician with new regenerative options at the point of care. Herein we detail exciting recent advances in medical devices that will aid in the safe and efficacious delivery of cell-based therapeutics.
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Affiliation(s)
- Eoin D O'Cearbhaill
- Department of Medicine, Center for Regenerative Therapeutics, and Department of Medicine, Division of Biomedical Engineering, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Harvard Stem Cell Institute, Cambridge, MA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA; School of Mechanical and Materials Engineering, University College Dublin, Dublin, Ireland
| | - Kelvin S Ng
- Department of Medicine, Center for Regenerative Therapeutics, and Department of Medicine, Division of Biomedical Engineering, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Harvard Stem Cell Institute, Cambridge, MA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA
| | - Jeffrey M Karp
- Department of Medicine, Center for Regenerative Therapeutics, and Department of Medicine, Division of Biomedical Engineering, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Harvard Stem Cell Institute, Cambridge, MA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA.
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Cai R, Schally AV, Cui T, Szalontay L, Halmos G, Sha W, Kovacs M, Jaszberenyi M, He J, Rick FG, Popovics P, Kanashiro-Takeuchi R, Hare JM, Block NL, Zarandi M. Synthesis of new potent agonistic analogs of growth hormone-releasing hormone (GHRH) and evaluation of their endocrine and cardiac activities. Peptides 2014; 52:104-12. [PMID: 24373935 PMCID: PMC4745889 DOI: 10.1016/j.peptides.2013.12.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 12/17/2013] [Accepted: 12/18/2013] [Indexed: 11/30/2022]
Abstract
In view of the recent findings of stimulatory effects of GHRH analogs, JI-34, JI-36 and JI-38, on cardiomyocytes, pancreatic islets and wound healing, three series of new analogs of GHRH(1-29) have been synthesized and evaluated biologically in an endeavor to produce more potent compounds. "Agmatine analogs", MR-356 (N-Me-Tyr(1)-JI-38), MR-361(N-Me-Tyr(1), D-Ala(2)-JI-38) and MR-367(N-Me-Tyr(1), D-Ala(2), Asn(8)-JI-38), in which Dat in JI-38 is replaced by N-Me-Tyr(1), showed improved relative potencies on GH release upon subcutaneous administration in vivo and binding in vitro. Modification with N-Me-Tyr(1) and Arg(29)-NHCH3 as in MR-403 (N-Me-Tyr(1), D-Ala(2), Arg(29)-NHCH3-JI-38), MR-406 (N-Me-Tyr(1), Arg(29)-NHCH3-JI-38) and MR-409 (N-Me-Tyr(1), D-Ala(2), Asn(8), Arg(29)-NHCH3-JI-38), and MR-410 (N-Me-Tyr(1), D-Ala(2), Thr(8), Arg(29)-NHCH3-JI-38) resulted in dramatically increased endocrine activities. These appear to be the most potent GHRH agonistic analogs so far developed. Analogs with Apa(30)-NH2 such as MR-326 (N-Me-Tyr(1), D-Ala(2), Arg(29), Apa(30)-NH2-JI-38), and with Gab(30)-NH2, as MR-502 (D-Ala(2), 5F-Phe(6), Ser(28), Arg(29),Gab(30)-NH2-JI-38) also exhibited much higher potency than JI-38 upon i.v. administration. The relationship between the GH-releasing potency and the analog structure is discussed. Fourteen GHRH agonists with the highest endocrine potencies were subjected to cardiologic tests. MR-409 and MR-356 exhibited higher potency than JI-38 in activating myocardial repair in rats with induced myocardial infarction. As the previous class of analogs, exemplified by JI-38, had shown promising results in multiple fields including cardiology, diabetes and wound healing, our new, more potent, GHRH agonists should manifest additional efficacy for possible medical applications.
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Affiliation(s)
- Renzhi Cai
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States; Department of Pathology, University of Miami, Miller School of Medicine, Miami, FL, United States
| | - Andrew V Schally
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States; Department of Pathology, University of Miami, Miller School of Medicine, Miami, FL, United States; Division of Hematology/Oncology, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, United States; Division of Endocrinology, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, United States.
| | - Tengjiao Cui
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States; Department of Pathology, University of Miami, Miller School of Medicine, Miami, FL, United States
| | - Luca Szalontay
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States
| | - Gabor Halmos
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States; Department of Pathology, University of Miami, Miller School of Medicine, Miami, FL, United States
| | - Wei Sha
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States; Interdisciplinary Stem Cell Institute, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, United States
| | - Magdolna Kovacs
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States; Department of Pathology, University of Miami, Miller School of Medicine, Miami, FL, United States
| | - Miklos Jaszberenyi
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States
| | - Jinlin He
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States
| | - Ferenc G Rick
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States; Department of Urology, Florida International University, Herbert Wertheim College of Medicine, Miami, FL, United States
| | - Petra Popovics
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; Division of Cardiology, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, United States
| | - Rosemeire Kanashiro-Takeuchi
- Interdisciplinary Stem Cell Institute, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, United States
| | - Joshua M Hare
- Division of Cardiology, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, United States; Interdisciplinary Stem Cell Institute, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, United States
| | - Norman L Block
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States; Department of Pathology, University of Miami, Miller School of Medicine, Miami, FL, United States; Division of Hematology/Oncology, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, United States
| | - Marta Zarandi
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center, Miami, FL, United States; South Florida VA Foundation for Research and Education, Miami, FL, United States; Department of Pathology, University of Miami, Miller School of Medicine, Miami, FL, United States
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Ludwig B, Barthel A, Reichel A, Block NL, Ludwig S, Schally AV, Bornstein SR. Modulation of the pancreatic islet-stress axis as a novel potential therapeutic target in diabetes mellitus. VITAMINS AND HORMONES 2014; 95:195-222. [PMID: 24559919 DOI: 10.1016/b978-0-12-800174-5.00008-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Loss of pancreatic islet function and insulin-producing beta cell mass is a central hallmark in the pathogenesis of both type 1 and type 2 diabetes. While in type 1 diabetes this phenomenon is due to an extensive destruction of beta cells caused by an autoimmune process, the mechanisms resulting in beta cell failure in type 2 diabetes are different and less clear. Also, beta cell destruction in type 1 diabetes occurs early and is the initial step in the pathogenetic process, while beta cell loss in type 2 diabetes after an initial phase of hyperinsulinemia due to the underlying insulin resistance occurs relatively late and it is less pronounced. Since diabetes mellitus is the most frequent endocrine disease, with an increasing high prevalence worldwide, huge efforts have been made over the past many decades to identify predisposing genetic, environmental, and nutritional factors in order to develop effective strategies to prevent the disease. In parallel, extensive studies in different cell systems and animal models have helped to elucidate our understanding of the physiologic function of islets and to gain insight into the immunological and non-immunological mechanisms of beta cell destruction and failure. Furthermore, currently emerging concepts of beta cell regeneration (e.g., the restoration of the beta cell pool by regenerative, proliferative and antiapoptotic processes, and recovery of physiologic islet function) apparently is yielding the first promising results. Recent insights into the complex endocrine and paracrine mechanisms regulating the physiologic function of pancreatic islets, as well as beta cell life and death, constitute an essential part of this new and exciting area of diabetology. For example, understanding of the physiological role of glucagon-like peptide 1 has resulted in the successful clinical implementation of incretin-based therapies over the last years. Further, recent data suggesting paracrine effects of growth hormone-releasing hormone and corticotropin-releasing hormone on the regulation of pancreatic islet function, survival, and proliferation as well as on local glucocorticoid metabolism provide evidence for a potential role of the pancreatic islet-stress axis in the pathophysiology of diabetes mellitus. In this chapter, we provide a comprehensive overview of current preventive and regenerative concepts as a basis for the development of novel therapeutic approaches to the treatment of diabetes mellitus. A particular focus is given on the potential of the pancreatic islet-stress axis in the development of novel regenerative strategies.
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Affiliation(s)
- Barbara Ludwig
- Department of Medicine III, University Hospital Carl Gustav Carus, Dresden, Germany; The Paul Langerhans Institute, Dresden, Germany; Center for Regenerative Therapies Dresden, Dresden University of Technology, Dresden, Germany.
| | - Andreas Barthel
- Department of Medicine III, University Hospital Carl Gustav Carus, Dresden, Germany; Endokrinologikum Ruhr, Bochum, Germany
| | - Andreas Reichel
- Department of Medicine III, University Hospital Carl Gustav Carus, Dresden, Germany
| | - Norman L Block
- Department of Pathology, University of Miami Miller School of Medicine, Miami, Florida, USA; Department of Medicine, Division of Hematology-Oncology, University of Miami Miller School of Medicine, Miami, Florida, USA; Veterans Administration Medical Center, Miami, Florida, USA
| | - Stefan Ludwig
- Department of Visceral, Thorax and Vascular Surgery, University Hospital Carl Gustav Carus, Dresden, Germany
| | - Andrew V Schally
- Department of Pathology, University of Miami Miller School of Medicine, Miami, Florida, USA; Department of Medicine, Division of Endocrinology, University of Miami Miller School of Medicine, Miami, Florida, USA; Department of Medicine, Division of Hematology-Oncology, University of Miami Miller School of Medicine, Miami, Florida, USA; Veterans Administration Medical Center, Miami, Florida, USA
| | - Stefan R Bornstein
- Department of Medicine III, University Hospital Carl Gustav Carus, Dresden, Germany; The Paul Langerhans Institute, Dresden, Germany; Center for Regenerative Therapies Dresden, Dresden University of Technology, Dresden, Germany
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Abstract
Transplantation of pancreatic islets is emerging as a successful treatment for type-1 diabetes. Its current stringent restriction to patients with critical metabolic lability is justified by the long-term need for immunosuppression and a persistent shortage of donor organs. We developed an oxygenated chamber system composed of immune-isolating alginate and polymembrane covers that allows for survival and function of islets without immunosuppression. A patient with type-1 diabetes received a transplanted chamber and was followed for 10 mo. Persistent graft function in this chamber system was demonstrated, with regulated insulin secretion and preservation of islet morphology and function without any immunosuppressive therapy. This approach may allow for future widespread application of cell-based therapies.
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111
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Abstract
PURPOSE OF REVIEW This review evaluates recent progress in several approaches aimed at developing human surrogate β cells, and identifies gaps that need to be filled for bringing them closer to clinical application. RECENT FINDINGS Cells expanded in vitro from human cadaver donor β cells under conditions causing dedifferentiation have been shown to undergo redifferentiation following inhibition of the Notch pathway. Efforts for differentiation of insulin-producing cells from human pluripotent stem cells have focused on isolation and expansion of intermediate-stage cells. The role of mesenchyme in expansion of pancreas progenitors has been emphasized by mouse cell ablation, and co-culture of human embryonic stem cell-derived definitive endoderm with mesenchyme. Incomplete removal of Polycomb-mediated repression of endocrine genes in embryonic stem cell-derived insulin-producing cells generated in vitro has been suggested to be responsible for their immature phenotype. Induced pluripotent stem cells reprogrammed from β cells have been shown to exhibit an enhanced differentiation capacity toward insulin-producing cells, compared with other pluripotent stem cells. A new approach for reprogramming non-β into β-like cells involving transcription factor gene ablation has been demonstrated in mouse enteroendocrine cells in vivo. SUMMARY New insights into the stumbling blocks in expansion of human donor islet cells, differentiation of pluripotent stem cells, and reprogramming of non-β cell types are shaping improved strategies, which are likely to bring us closer to the goal of generating abundant human surrogate β cells.
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Affiliation(s)
- Shimon Efrat
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University Ramat Aviv, Tel Aviv, Israel.
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112
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Therapeutic cell encapsulation: Ten steps towards clinical translation. J Control Release 2013; 170:1-14. [DOI: 10.1016/j.jconrel.2013.04.015] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 04/05/2013] [Accepted: 04/22/2013] [Indexed: 12/23/2022]
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Nair D, Ramesh V, Li RC, Schally AV, Gozal D. Growth hormone releasing hormone (GHRH) signaling modulates intermittent hypoxia-induced oxidative stress and cognitive deficits in mouse. J Neurochem 2013; 127:531-40. [PMID: 23815362 DOI: 10.1111/jnc.12360] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 06/23/2013] [Accepted: 06/25/2013] [Indexed: 11/27/2022]
Abstract
Intermittent hypoxia (IH) during sleep, such as occurs in obstructive sleep apnea (OSA), leads to degenerative changes in the hippocampus, and is associated with spatial learning deficits in adult mice. In both patients and murine models of OSA, the disease is associated with suppression of growth hormone (GH) secretion, which is actively involved in the growth, development, and function of the central nervous system (CNS). Recent work showed that exogenous GH therapy attenuated neurocognitive deficits elicited by IH during sleep in rats. Here, we show that administration of the Growth Hormone Releasing Hormone (GHRH) agonist JI-34 attenuates IH-induced neurocognitive deficits, anxiety, and depression in mice along with reduction in oxidative stress markers such as MDA and 8-hydroxydeoxyguanosine, and increases in hypoxia inducible factor-1α DNA binding and up-regulation of insulin growth factor-1 and erythropoietin expression. In contrast, treatment with a GHRH antagonist (MIA-602) during intermittent hypoxia did not affect any of the IH-induced deleterious effects in mice. Thus, exogenous GHRH administered as the formulation of a GHRH agonist may provide a viable therapeutic intervention to protect IH-vulnerable brain regions from OSA-associated neurocognitive dysfunction. Sleep apnea, characterized by chronic intermittent hypoxia (IH), is associated with substantial cognitive and behavioral deficits. Here, we show that administration of a GHRH agonist (JI-34) reduces oxidative stress, increases both HIF-1α nuclear binding and downstream expression of IGF1 and erythropoietin (EPO) in hippocampus and cortex, and markedly attenuates water maze performance deficits in mice exposed to intermittent hypoxia during sleep.
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Affiliation(s)
- Deepti Nair
- Department of Pediatrics, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA
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Coronel MM, Stabler CL. Engineering a local microenvironment for pancreatic islet replacement. Curr Opin Biotechnol 2013; 24:900-8. [PMID: 23769320 DOI: 10.1016/j.copbio.2013.05.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 05/16/2013] [Accepted: 05/17/2013] [Indexed: 01/10/2023]
Abstract
Intraportal islet transplantation has emerged as a promising treatment for type 1 diabetes mellitus (T1DM). Nevertheless, long-term efficacy has been limited to a marginal number of patients. Outcomes have been restricted, in part, by challenges associated with the transplant site, poor vascularization, and disruption of the native islet architecture during the isolation process. Engineering a biomaterial platform that recapitulates critical components of the pancreatic environment can serve to address these hurdles. This review highlights the challenges and opportunities in engineering 3D niches for islets, specifically: the importance of site selection; the application of scaffold functionalization to present bioactive motifs; and the development of technologies for enhancing implant nutritional profiles. The potential of these novel approaches to improve islet engraftment and duration of function is discussed.
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Affiliation(s)
- Maria M Coronel
- Department of Biomedical Engineering, College of Engineering, University of Miami, Coral Gables, FL 33146, United States; Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, FL 33136, United States
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A Short-activating RNA Oligonucleotide Targeting the Islet β-cell Transcriptional Factor MafA in CD34(+) Cells. MOLECULAR THERAPY. NUCLEIC ACIDS 2013; 2:e97. [PMID: 23736775 PMCID: PMC3696904 DOI: 10.1038/mtna.2013.23] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Upon functional loss of insulin producing islet β-cells, some patients with diabetes become dependent on life-long insulin supplementation therapy. Bioengineering surrogate insulin producing cells is an alternative replacement strategy. We have developed a novel approach using short-activating RNA oligonucleotides to differentiate adult human CD34(+) cells into insulin-secreting cells. By transfecting RNA to increase transcript levels of the master regulator of insulin biosynthesis, v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MafA), several pancreatic endodermal genes were upregulated during the differentiation procedure. These included Pancreatic and duodenal homeobox gene-1 (PDX1), Neurogenin 3, NeuroD, and NK6 homeobox 1 (NKx6-1). Differentiated CD34(+) cells also expressed glucokinase, glucagon-like peptide 1 receptor (GLP1R), sulfonylurea receptor-1 (SUR1) and phogrin-all essential for glucose sensitivity and insulin secretion. The differentiated cells appropriately processed C-peptide and insulin in response to increasing glucose stimulation as shown by enzyme-linked immunosorbent assay (ELISA), fluorescence-activated cell sorting analysis, western blotting, and immunofluorescence staining. We provide a new approach using short-activating RNA in developing insulin producing surrogate cells for treating diabetes.Molecular Therapy - Nucleic Acids (2013) 2, e97; doi:10.1038/mtna.2013.23; advance online publication 4 June 2013.
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Abstract
Islet transplantation has been shown to be a viable treatment option for patients afflicted with type 1 diabetes. However, the lack of availablity of human pancreases and the need to use risky immunosuppressive drugs to prevent transplant rejection remain two major obstacles to the routine use of islet transplantation in diabetic patients. Successful development of a bioartificial pancreas using the approach of microencapsulation with perm-selective coating of islets in hydrogels for graft immunoisolation holds tremendous promise for diabetic patients because it has great potential to overcome these two barriers. In this review article, we will discuss the need for a bioartificial pancreas, provide a detailed description of the microencapsulation process, and review the status of the technology in clinical development. We will also critically review the various factors that will need to be taken into consideration in order to achieve the ultimate goal of routine clinical application.
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Affiliation(s)
- Rajesh A Pareta
- Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Alan C Farney
- Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
- Department of Surgery, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Emmanuel C Opara
- Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
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117
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Affiliation(s)
- Alexandra M Smink
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
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118
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Renner S, Braun-Reichhart C, Blutke A, Herbach N, Emrich D, Streckel E, Wünsch A, Kessler B, Kurome M, Bähr A, Klymiuk N, Krebs S, Puk O, Nagashima H, Graw J, Blum H, Wanke R, Wolf E. Permanent neonatal diabetes in INS(C94Y) transgenic pigs. Diabetes 2013; 62:1505-11. [PMID: 23274907 PMCID: PMC3636654 DOI: 10.2337/db12-1065] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mutations in the insulin (INS) gene may cause permanent neonatal diabetes mellitus (PNDM). Ins2 mutant mouse models provided important insights into the disease mechanisms of PNDM but have limitations for translational research. To establish a large animal model of PNDM, we generated INS(C94Y) transgenic pigs. A line expressing high levels of INS(C94Y) mRNA (70-86% of wild-type INS transcripts) exhibited elevated blood glucose soon after birth but unaltered β-cell mass at the age of 8 days. At 4.5 months, INS(C94Y) transgenic pigs exhibited 41% reduced body weight, 72% decreased β-cell mass (-53% relative to body weight), and 60% lower fasting insulin levels compared with littermate controls. β-cells of INS(C94Y) transgenic pigs showed a marked reduction of insulin secretory granules and severe dilation of the endoplasmic reticulum. Cataract development was already visible in 8-day-old INS(C94Y) transgenic pigs and became more severe with increasing age. Diabetes-associated pathological alterations of kidney and nervous tissue were not detected during the observation period of 1 year. The stable diabetic phenotype and its rescue by insulin treatment make the INS(C94Y) transgenic pig an attractive model for insulin supplementation and islet transplantation trials, and for studying developmental consequences of maternal diabetes mellitus.
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Affiliation(s)
- Simone Renner
- Chair for Molecular Animal Breeding and Biotechnology, Ludwig Maximilian University Munich, Munich, Germany
| | - Christina Braun-Reichhart
- Chair for Molecular Animal Breeding and Biotechnology, Ludwig Maximilian University Munich, Munich, Germany
| | - Andreas Blutke
- Institute of Veterinary Pathology at the Centre for Clinical Veterinary Medicine, Ludwig Maximilian University Munich, Munich, Germany
| | - Nadja Herbach
- Institute of Veterinary Pathology at the Centre for Clinical Veterinary Medicine, Ludwig Maximilian University Munich, Munich, Germany
| | - Daniela Emrich
- Institute of Veterinary Pathology at the Centre for Clinical Veterinary Medicine, Ludwig Maximilian University Munich, Munich, Germany
| | - Elisabeth Streckel
- Chair for Molecular Animal Breeding and Biotechnology, Ludwig Maximilian University Munich, Munich, Germany
| | - Annegret Wünsch
- Chair for Molecular Animal Breeding and Biotechnology, Ludwig Maximilian University Munich, Munich, Germany
| | - Barbara Kessler
- Chair for Molecular Animal Breeding and Biotechnology, Ludwig Maximilian University Munich, Munich, Germany
| | - Mayuko Kurome
- Chair for Molecular Animal Breeding and Biotechnology, Ludwig Maximilian University Munich, Munich, Germany
- Meiji University, International Institute for Bio-Resource Research, Kawasaki, Japan
| | - Andrea Bähr
- Chair for Molecular Animal Breeding and Biotechnology, Ludwig Maximilian University Munich, Munich, Germany
| | - Nikolai Klymiuk
- Chair for Molecular Animal Breeding and Biotechnology, Ludwig Maximilian University Munich, Munich, Germany
| | - Stefan Krebs
- Laboratory for Functional Genome Analysis, Gene Center, Ludwig Maximilian University Munich, Munich, Germany
| | - Oliver Puk
- Helmholtz Center Munich-German Research Center for Environmental Health, Institute of Developmental Genetics, Neuherberg, Germany
| | - Hiroshi Nagashima
- Meiji University, International Institute for Bio-Resource Research, Kawasaki, Japan
| | - Jochen Graw
- Helmholtz Center Munich-German Research Center for Environmental Health, Institute of Developmental Genetics, Neuherberg, Germany
| | - Helmut Blum
- Helmholtz Center Munich-German Research Center for Environmental Health, Institute of Developmental Genetics, Neuherberg, Germany
| | - Ruediger Wanke
- Institute of Veterinary Pathology at the Centre for Clinical Veterinary Medicine, Ludwig Maximilian University Munich, Munich, Germany
| | - Eckhard Wolf
- Chair for Molecular Animal Breeding and Biotechnology, Ludwig Maximilian University Munich, Munich, Germany
- Laboratory for Functional Genome Analysis, Gene Center, Ludwig Maximilian University Munich, Munich, Germany
- Meiji University, International Institute for Bio-Resource Research, Kawasaki, Japan
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Islet Transplantation in a Subarachnoid Cavity Surrounding Olfactory Bulb of Diabetic Rats. Transplantation 2013; 95:e54-7. [DOI: 10.1097/tp.0b013e3182875ddc] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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120
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Grundfest-Broniatowski S. What would surgeons like from materials scientists? WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2013; 5:299-319. [PMID: 23533092 DOI: 10.1002/wnan.1220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Surgery involves the repair, resection, replacement, or improvement of body parts and functions and in numerous ways, surgery should be considered human engineering. There are many areas in which surgical materials could be improved, but surgeons are generally unaware of materials available for use, while materials scientists do not know what surgeons require. This article will review some of the areas where surgeons and materials scientists have interacted in the past and will discuss some of the most pressing problems which remain to be solved. These include better implant materials for hernia repair, breast reconstruction, the treatment of diabetes, vascular stenting and reconstruction, and electrical pacing devices. The combination of tissue engineering and nanomaterials has great potential for application to nearly every aspect of surgery. Tissue engineering will allow cells or artificial organs to be grown for specific uses while nanotechnology will help to ensure maximal biocompatibility. Biosensors will be combined with improved electrodes and pacing devices to control impaired neurological functions.
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121
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Vakhshiteh F, Allaudin ZN, Mohd Lila MAB, Hani H. Size-related assessment on viability and insulin secretion of caprine islets in vitro. Xenotransplantation 2013; 20:82-8. [PMID: 23406308 DOI: 10.1111/xen.12023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 01/07/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND The successful isolation, purification, and culture of caprine islets has recently been reported. The present study shows arange of size distribution in caprine islet diameter from 50 to 250 μm, in which 80% of the total islet yield was comprised of small islets. METHODS Caprine islets were isolated and purified. Islets were handpicked and the diameter of the islets was recorded using light microscopy. Viablility of the islets was analyzed by confocal microscopy. Insulin secretion assay was carried out and analyzed by ELISA. RESULTS When tested at 48 h after isolation, these small islets were 29.3% more viable compared to the large-sized islets. Large islets showed a high ratio (P < 0.01) of central core necrosis (29.5% ± 1.92) whilst no significant core death was observed in small islets (2.33% ± 0.59). The annexin assay demonstrated 5.21% ± 0.97 and 7.34% ± 0.78 apoptotic death for small and large islets, respectively. During static incubation, small islets released 2.89-fold (1.39 ± 0.2 ng/IE) higher insulin level under low glucose induction (3.3 mm) and simultaneously 2.92-fold (2.95 ± 0.33 ng/IE) more insulin under high glucose condition (16.7 mm) in comparison to large islets at the same islet equivalents (P < 0.05). CONCLUSION The present findings evidenced the superior quality of smaller caprine islets compared to larger ones under an optimized basal maintenance condition. As it is equally important to preserve the quality of larger caprine islets, this work warrants further investigation on special culture conditions to support these islets.
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Affiliation(s)
- Faezeh Vakhshiteh
- Institute of Bioscience, Universiti Putra Malaysia, 43300 Serdang, Selangor, Malaysia
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Mueller KR, Balamurugan AN, Cline GW, Pongratz RL, Hooper RL, Weegman BP, Kitzmann JP, Taylor MJ, Graham ML, Schuurman HJ, Papas KK. Differences in glucose-stimulated insulin secretion in vitro of islets from human, nonhuman primate, and porcine origin. Xenotransplantation 2013; 20:75-81. [PMID: 23384163 DOI: 10.1111/xen.12022] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 12/28/2012] [Indexed: 01/15/2023]
Abstract
Porcine islet xenotransplantation is considered a potential cell-based therapy for type 1 diabetes. It is currently being evaluated in diabetic nonhuman primates (NHP) to assess safety and efficacy of the islet product. However, due to a variety of distinct differences between the respective species, including the insulin secretory characteristics of islets, the suitability and predictive value of the preclinical model in the extrapolation to the clinical setting remain a critical issue. Islets isolated from human (n = 3), NHP (n = 2), adult pig (AP, n = 3), and juvenile pig (JP, n = 4) pancreata were perifused with medium at basal glucose (2.5 mm) followed by high glucose (16.7 mm) concentrations. The total glucose-stimulated insulin secretion (GSIS) was calculated from generated insulin secretion profiles. Nonhuman primate islets exhibited GSIS 3-fold higher than AP islets, while AP and JP islets exhibited GSIS 1/3 and 1/30 of human islets, respectively. The insulin content of NHP and AP islets was similar to that of human islets, whereas that of JP islets was 1/5 of human islets. Despite the fact that human, NHP, and AP islets contain similar amounts of insulin, the much higher GSIS for NHP islets than for AP and JP islets suggests the need for increased dosing of islets from JP and AP in pig-to-NHP transplantation. Porcine islet xenotransplantation to humans may require significantly higher dosing given the lower GSIS of AP islets compared to human islets.
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Affiliation(s)
- Kate R Mueller
- Department of Surgery, Schulze Diabetes Institute, University of Minnesota, Minneapolis, MN, USA
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123
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Transplantation of pancreatic islets to adrenal gland is promoted by agonists of growth-hormone-releasing hormone. Proc Natl Acad Sci U S A 2013; 110:2288-93. [PMID: 23345449 DOI: 10.1073/pnas.1221505110] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Here, we evaluate an alternative approach of preconditioning pancreatic islets before transplantation using a potent agonist of growth-hormone-releasing hormone (GHRH) to promote islet viability and function, and we explore the adrenal gland as an alternative transplantation site for islet engraftment. The endocrine microenvironment of the adrenal represents a promising niche with the unique advantages of exceptional high oxygen tension and local anti-inflammatory and immunosuppressive properties. GHRH agonists have been shown to promote islet graft survival and function, which may help to reduce the islet mass necessary to reverse diabetes. In the present study, the most potent GHRH agonist MR403 was tested on insulinoma cells, isolated rat islets, and adrenal β-cell cocultures in vitro. GHRH receptor is expressed on both adrenal cells and islets. MR403 caused a significant increase in cell viability and proliferation and revealed an antiapoptotic effect on insulinoma cells. Viability of rat islets was increased after treatment with the agonist and in coculture with adrenal cells. Rat islets were transplanted into diabetic mice to the intraadrenal transplant site and compared with the classical transplants underneath the kidney capsule. Graft function and integration were tested by metabolic follow-up and immunohistochemical staining of intraadrenal grafts. A rapid decrease occurred in blood glucose levels in both models, and all animals reached normoglycemia within the first days after transplantation. Our studies demonstrated that the adrenal may be an attractive site for islet transplantation and that GHRH analogs might allow reduction of the islet mass needed to reverse a diabetic status.
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Rick FG, Seitz S, Schally AV, Szalontay L, Krishan A, Datz C, Stadlmayr A, Buchholz S, Block NL, Hohla F. GHRH antagonist when combined with cytotoxic agents induces S-phase arrest and additive growth inhibition of human colon cancer. Cell Cycle 2012; 11:4203-10. [PMID: 23095641 DOI: 10.4161/cc.22498] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Treatment of colon cancer with an antagonist of growth hormone-releasing hormone (GHRH), JMR-132, results in a cell cycle arrest in S-phase of the tumor cells. Thus, we investigated the effect of JMR-132 in combination with S-phase-specific cytotoxic agents, 5-FU, irinotecan and cisplatin on the in vitro and in vivo growth of HT-29, HCT-116 and HCT-15 human colon cancer cell lines. In vitro, every compound inhibited proliferation of HCT-116 cells in a dose-dependent manner. Treatment with JMR-132 (5 μM) combined with 5-FU (1.25 μM), irinotecan (1.25 μM) or cisplatin (1.25 μM) resulted in an additive growth inhibition of HCT-116 cells in vitro as shown by MTS assay. Cell cycle analyses revealed that treatment of HCT-116 cells with JMR-132 was accompanied by a cell cycle arrest in S-phase. Combination treatment using JMR-132 plus a cytotoxic drug led to a significant increase of the sub-G 1 fraction, suggesting apoptosis. In vivo, daily treatment with GHRH antagonist JMR-132 decreased the tumor volume by 40-55% (p < 0.001) of HT-29, HCT-116 and HCT-15 tumors xenografted into athymic nude mice. Combined treatment with JMR-132 plus chemotherapeutic agents 5-FU, irinotecan or cisplatin resulted in an additive tumor growth suppression of HT-29, HCT-116 and HCT-15 xenografts to 56-85%. Our observations indicate that JMR-132 enhances the antiproliferative effect of S-phase-specific cytotoxic drugs by causing accumulation of tumor cells in S-phase.
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Affiliation(s)
- Ferenc G Rick
- Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center and South Florida Veterans Affairs Foundation for Research and Education, Miami, FL, USA
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de Vos P, Spasojevic M, de Haan BJ, Faas MM. The association between in vivo physicochemical changes and inflammatory responses against alginate based microcapsules. Biomaterials 2012; 33:5552-9. [DOI: 10.1016/j.biomaterials.2012.04.039] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 04/13/2012] [Indexed: 12/20/2022]
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