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Truong W, Shapiro AMJ. Progress in islet transplantation in patients with type 1 diabetes mellitus. ACTA ACUST UNITED AC 2016; 5:147-58. [PMID: 16677057 DOI: 10.2165/00024677-200605030-00003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
More than 500 patients with type 1 diabetes mellitus have now received islet transplants at over 50 institutions worldwide in the past 5 years. Rates of insulin independence at 1 year with current protocols are impressive. However, inexorable decay of islet function over time indicates that there are many opportunities for improvement. Improved control of glycosylated hemoglobin and reduced risk of recurrent hypoglycemia are seen as important benefits of islet transplantation, irrespective of the status regarding insulin independence. For the use of islet transplantation to expand it is essential that the donor-to-recipient ratio be reliably reduced to 1 : 1. Enormous opportunities lie ahead for the development of successful living donor islet transplantation, single donor protocols, improved engraftment, islet proliferation in vitro and in the recipient, alternative islet sources, and novel tolerizing drugs. With these emerging opportunities, islet transplantation may expand to include more patients with type 1 diabetes, including children, and will not be restricted to the most unstable forms of the disease, as it is today.
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Affiliation(s)
- Wayne Truong
- Department of Surgery, Faculty of Medicine, University of Alberta, Edmonton, Alberta, Canada
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Failure to achieve normal metabolic response in non-obese diabetic mice and streptozotocin-induced diabetic mice after transplantation of primary murine hepatocytes electroporated with the human proinsulin gene (p3MTChins). Transplant Proc 2015; 46:2002-6. [PMID: 25131094 DOI: 10.1016/j.transproceed.2014.05.068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND A recent study by Chen et al described a therapy for diabetes that involved electroporation of primary hepatocytes with human proinsulin cDNA, p3MTChins. Intrahepatic transplantation of treated hepatocytes into streptozotocin (STZ) murine and porcine models led to euglycemia, weight maintenance, and normal insulin production. We tested the repeatability of their basic experiments and transplantation technique and expanded the study to include an autoimmune model. METHODS Hepatocytes were isolated from B6 mice, electroporated with p3MTChins, and glucose-challenged or were injected into hepatic or spleen parenchyma of STZ-diabetic B6 and non-obese diabetic mice. Outcomes included survival, serum glucose levels, insulin, and c-peptide release. Untransfected primary hepatocytes and mice transplanted with these cells served as controls. RESULTS p3MTChins-hepatocytes secreted insulin during glucose challenge, but glucose levels did not change with increasing glucose concentrations. Direct hepatic injection led to high mortality rates. Mice that underwent intrasplenic injection survived for >50 days (control = 4 days) and had a mild but stable improvement in hyperglycemia. C-peptide in both mouse models was detectable but eventually declined to baseline in the non-obese diabetic mice. CONCLUSIONS Hepatocytes can be transfected with p3MTChins to produce human insulin but may lack the proper glucose-sensing or complex storage and secretion capabilities that allow for a finely tuned dynamic insulin response. Treatment is subtherapeutic, and p3MTChins-hepatocyte function may not endure in an autoimmune model. Without successful preliminary findings, cell therapy involving electroporation of p3MTChins does not appear to be practical as a therapy for diabetes and may not be a strategy to pursue at this time.
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Liu YY, Jia W, Wanke IE, Muruve DA, Xiao HP, Wong NCW. Glucose regulates secretion of exogenously expressed insulin from HepG2 cells in vitro and in a mouse model of diabetes mellitus in vivo. J Mol Endocrinol 2013; 50:337-46. [PMID: 23475748 DOI: 10.1530/jme-12-0239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glucose-controlled insulin secretion is a key component of its regulation. Here, we examined whether liver cell secretion of insulin derived from an engineered construct can be regulated by glucose. Adenovirus constructs were designed to express proinsulin or mature insulin containing the conditional binding domain (CBD). This motif binds GRP78 (HSPA5), an endoplasmic reticulum (ER) protein that enables the chimeric hormone to enter into and stay within the ER until glucose regulates its release from the organelle. Infected HepG2 cells expressed proinsulin mRNA and the protein containing the CBD. Immunocytochemistry studies suggested that GRP78 and proinsulin appeared together in the ER of the cell. The amount of hormone released from infected cells varied directly with the ambient concentration of glucose in the media. Glucose-regulated release of the hormone from infected cells was rapid and sustained. Removal of glucose from the cells decreased release of the hormone. In streptozotocin-induced diabetic mice, when infected with adenovirus expressing mature insulin, glucose levels declined. Our data show that glucose regulates release of exogenously expressed insulin from the ER of liver cells. This approach may be useful in devising new ways to treat diabetes mellitus.
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Affiliation(s)
- Y Y Liu
- Department of Endocrinology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510080, People's Republic of China
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Abstract
Stem cell therapy holds immense promise for the treatment of patients with diabetes mellitus. Research on the ability of human embryonic stem cells to differentiate into islet cells has defined the developmental stages and transcription factors involved in this process. However, the clinical applications of human embryonic stem cells are limited by ethical concerns, as well as the potential for teratoma formation. As a consequence, alternative forms of stem cell therapies, such as induced pluripotent stem cells, umbilical cord stem cells and bone marrow-derived mesenchymal stem cells, have become an area of intense study. Recent advances in stem cell therapy may turn this into a realistic treatment for diabetes in the near future.
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Affiliation(s)
- KO Lee
- Department of Medicine, National University of Singapore, Singapore
| | - SU Gan
- Department of Surgery, National University of Singapore, Singapore
| | - RY Calne
- Department of Medicine and Surgery, National University of Singapore, Singapore
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Gao S, Seker E, Casali M, Wang F, Bale SS, Price GM, Yarmush ML. Ex vivo gene delivery to hepatocytes: techniques, challenges, and underlying mechanisms. Ann Biomed Eng 2012; 40:1851-61. [PMID: 22484829 PMCID: PMC3901163 DOI: 10.1007/s10439-012-0555-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 03/19/2012] [Indexed: 01/01/2023]
Abstract
Gene delivery to primary hepatocytes is an important tool for a number of applications including the study of liver cell biology and pathology, drug screening, and gene therapy. Robust transfection of primary hepatocytes, however, is significantly more difficult to achieve than in cell lines or readily dividing primary cells. In this report, we investigated in vitro gene delivery to both primary rat hepatocytes and Huh7.5.1 cells (a hepatoma cell line) using a number of viral and non-viral methods, including Lipofectamine 2000, FuGene HD, Nucleofection, Magnetofection, and lentiviruses. Our results showed that Lipofectamine 2000 is the most efficient reagent for green fluorescent protein (GFP) gene delivery to primary rat hepatocytes (33.3 ± 1.8% transfection efficiency) with minimal adverse effect on several hepatic functions, such as urea and albumin secretion. The lentiviral vectors used in this study exhibited undetectable gene delivery to primary rat hepatocytes but significant delivery to Huh7.5.1 cells (>80% transfection efficiency). In addition, we demonstrated lentiviral-based and spatially defined delivery of the GFP gene to Huh7.5.1 cells for use in biological microelectromechanical systems.
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Affiliation(s)
- Shan Gao
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, 51 Blossom Street, Boston, MA 02114, USA
| | - Erkin Seker
- Department of Electrical and Computer Engineering, University of California Davis, Davis, CA 95616, USA
| | - Monica Casali
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, 51 Blossom Street, Boston, MA 02114, USA
| | - Fangjing Wang
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, 51 Blossom Street, Boston, MA 02114, USA
| | - Shyam Sundhar Bale
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, 51 Blossom Street, Boston, MA 02114, USA
| | - Gavrielle M. Price
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, 51 Blossom Street, Boston, MA 02114, USA
| | - Martin L. Yarmush
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, 51 Blossom Street, Boston, MA 02114, USA
- Department of Biomedical Engineering, Rutgers University, Piscataway, NJ 08854, USA
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Insulin expressed from endogenously active glucose-responsive EGR1 promoter in bone marrow mesenchymal stromal cells as diabetes therapy. Gene Ther 2010; 17:592-605. [PMID: 20182520 DOI: 10.1038/gt.2010.12] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Advances in islet transplantation have encouraged efforts to create alternative insulin-secreting cells that overcome limitations associated with current therapies. We have recently demonstrated durable correction of murine and porcine diabetes by syngeneic and autologous implantation, respectively, of primary hepatocytes non-virally modified with a glucose-responsive promoter-regulated insulin transgene. As surgical procurement of hepatocytes may be clinically unappealing, we here describe primary bone marrow-derived mesenchymal stromal cells (BMMSC) as alternative insulin-secreting bioimplants. BMMSC are abundant and less invasively procured for clinical autologous transplantation. Electroporation achieved high transgene transfection efficiencies in human BMMSC (HBMMSC) and porcine BMMSC (PBMMSC). We transcriptomically identified an HBMMSC glucose-responsive promoter, EGR1. This endogenously active promoter drove rapid glucose-induced transgene secretions in BMMSC with near-physiological characteristics during static and kinetic induction assays simulating normal human islets. Preparatory to preclinical transplantation, PBMMSC transfected with the circular insulin transgene vector or stably integrated with the linearized vector were evaluated by intrahepatic or intraperitoneal xenotransplantation in streptozotocin-diabetic and non-diabetic NOD-SCID mice. Hyperglycemia, glucose tolerance and body weight were corrected in a dose-responsive manner. Hypoglycemia was not observed even in identically implanted non-diabetic mice. These results establish human EGR1 promoter-insulin construct-modified BMMSC as safe and efficient insulin-secreting bioimplants for diabetes treatment.
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Unniappan S, Wideman RD, Donald C, Gunn V, Wall JL, Zhang QX, Webber TD, Cheung AT, Kieffer TJ. Treatment of diabetes by transplantation of drug-inducible insulin-producing gut cells. J Mol Med (Berl) 2009; 87:703-12. [DOI: 10.1007/s00109-009-0465-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Revised: 02/25/2009] [Accepted: 03/19/2009] [Indexed: 10/20/2022]
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Chen NKF, Wong JS, Kee IHC, Lai SH, Thng CH, Ng WH, Ng RTH, Tan SY, Lee SY, Tan MEH, Sivalingam J, Chow PKH, Kon OL. Nonvirally modified autologous primary hepatocytes correct diabetes and prevent target organ injury in a large preclinical model. PLoS One 2008; 3:e1734. [PMID: 18320053 PMCID: PMC2249706 DOI: 10.1371/journal.pone.0001734] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 01/22/2008] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Current gene- and cell-based therapies have significant limitations which impede widespread clinical application. Taking diabetes mellitus as a paradigm, we have sought to overcome these limitations by ex vivo electrotransfer of a nonviral insulin expression vector into primary hepatocytes followed by immediate autologous reimplantation in a preclinical model of diabetes. METHODS AND RESULTS In a single 3-hour procedure, hepatocytes were isolated from a surgically resected liver wedge, electroporated with an insulin expression plasmid ex vivo and reimplanted intraparenchymally under ultrasonic guidance into the liver in each of 10 streptozotocin-induced diabetic Yorkshire pigs. The vector was comprised of a bifunctional, glucose-responsive promoter linked to human insulin cDNA. Ambient glucose concentrations appropriately altered human insulin mRNA expression and C-peptide secretion within minutes in vitro and in vivo. Treated swine showed correction of hyperglycemia, glucose intolerance, dyslipidemia and other metabolic abnormalities for > or = 47 weeks. Metabolic correction correlated significantly with the number of hepatocytes implanted. Importantly, we observed no hypoglycemia even under fasting conditions. Direct intrahepatic implantation of hepatocytes did not alter biochemical indices of liver function or induce abnormal hepatic lobular architecture. About 70% of implanted hepatocytes functionally engrafted, appeared histologically normal, retained vector DNA and expressed human insulin for > or = 47 weeks. Based on structural tissue analyses and transcriptome data, we showed that early correction of diabetes attenuated and even prevented pathological changes in the eye, kidney, liver and aorta. CONCLUSIONS We demonstrate that autologous hepatocytes can be efficiently, simply and safely modified by electroporation of a nonviral vector to express, process and secrete insulin durably. This strategy, which achieved significant and sustained therapeutic efficacy in a large preclinical model without adverse effects, warrants consideration for clinical development especially as it could have broader future applications for the treatment of other acquired and inherited diseases for which systemic reconstitution of a specific protein deficiency is critical.
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Affiliation(s)
- Nelson K. F. Chen
- Division of Medical Sciences, National Cancer Centre, Singapore, Republic of Singapore
| | - Jen San Wong
- Division of Medical Sciences, National Cancer Centre, Singapore, Republic of Singapore
- Department of General Surgery, Singapore General Hospital, Singapore, Republic of Singapore
| | - Irene H. C. Kee
- Department of Experimental Surgery, Singapore General Hospital, Singapore, Republic of Singapore
| | - Siang Hui Lai
- Centre for Forensic Medicine, Health Sciences Authority, Singapore, Republic of Singapore
| | - Choon Hua Thng
- Department of Oncologic Imaging, National Cancer Centre, Singapore, Republic of Singapore
| | - Wai Har Ng
- Division of Medical Sciences, National Cancer Centre, Singapore, Republic of Singapore
| | - Robert T. H. Ng
- Department of Experimental Surgery, Singapore General Hospital, Singapore, Republic of Singapore
| | - Soo Yong Tan
- Department of Pathology, Singapore General Hospital, Singapore, Republic of Singapore
| | - Shu Yen Lee
- Singapore National Eye Centre, Singapore, Republic of Singapore
| | - Mark E. H. Tan
- Division of Medical Sciences, National Cancer Centre, Singapore, Republic of Singapore
| | | | - Pierce K. H. Chow
- Department of General Surgery, Singapore General Hospital, Singapore, Republic of Singapore
- Department of Experimental Surgery, Singapore General Hospital, Singapore, Republic of Singapore
| | - Oi Lian Kon
- Division of Medical Sciences, National Cancer Centre, Singapore, Republic of Singapore
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Insulin-expressing engineered cell lines and primary cells: surrogate β cells from liver, gut, and other sources. Curr Opin Organ Transplant 2007; 12:67-72. [PMID: 27792092 DOI: 10.1097/mot.0b013e32801145eb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Islet transplantation is being used to treat type 1 diabetes but is currently limited by the shortage of tissue available and by insufficient long-term function of transplanted islets. Thus, there remains significant interest in developing substitute sources of insulin-producing cells. Here we review progress in this area, focusing on insulin gene therapy and generation of new insulin-producing cells by redirecting hepatic and intestinal tissues towards a β-cell phenotype. RECENT FINDINGS Insulin gene therapy using non-β cells has been improved by utilizing modified insulin constructs controlled by regulatory elements to confer nutrient responsiveness, and by inducing insulin production in endocrine cells that are equipped for rapid and in some cases glucose-responsive secretion. Significant advances have also been made towards generation of insulin-producing cells via transcriptional manipulation of hepatic and intestinal cells. These approaches offer the potential of generating a virtually limitless supply of insulin-producing cells. SUMMARY The major challenge associated with insulin gene therapy in non-β cells is to achieve rapid, glucose-responsive secretion, while transdifferentiation approaches require additional characterization of the function and stability of insulin-producing cells. Continued efforts in these areas are warranted, as re-establishment of endogenous insulin production would be a welcome replacement to insulin injections for diabetes treatment.
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Abstract
DM (diabetes mellitus) is a metabolic disorder of either absolute or relative insulin deficiency. Optimized insulin injections remain the mainstay life-sustaining therapy for patients with T1DM (Type I DM) in 2006; however, a small subset of patients with T1DM (approx. 10%) are exquisitely sensitive to insulin and lack counter-regulatory measures, putting them at higher risk of neuroglycopenia. One alternative strategy to injected insulin therapy is pancreatic islet transplantation. Islet transplantation came of age when Paul E. Lacy successfully reversed chemical diabetes in rodent models in 1972. In a landmark study published in 2000, Shapiro et al. [A. M. Shapiro, J. R. Lakey, E. A. Ryan, G. S. Korbutt, E. Toth, G. L. Warnock, N. M. Kneteman and R. V. Rajotte (2000) N. Engl. J. Med. 343, 230-238] reported seven consecutive patients treated with islet transplants under the Edmonton protocol, all of whom maintained insulin independence out to 1 year. Substantial progress has occurred in aspects of pancreas procurement, transportation (using the oxygenated two-layer method) and in islet isolation (with controlled enzymatic perfusion and subsequent digestion in the Ricordi chamber). Clinical protocols to optimize islet survival and function post-transplantation improved dramatically with the introduction of the Edmonton protocol, but it is clear that this approach still has potential limitations. Newer pharmacotherapies and interventions designed to promote islet survival, prevent apoptosis, to promote islet growth and to protect islets in the long run from immunological injury are rapidly approaching clinical trials, and it seems likely that clinical outcomes of islet transplantation will continue to improve at the current exponential pace.
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Affiliation(s)
- Shaheed Merani
- Clinical Islet Transplant Program, University of Alberta, Roberts Centre, 2000 College Plaza, Edmonton, Alberta, Canada T6G 2C8
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Malphettes L, Fussenegger M. Impact of RNA interference on gene networks. Metab Eng 2006; 8:672-83. [PMID: 16996764 DOI: 10.1016/j.ymben.2006.07.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 05/28/2006] [Accepted: 07/25/2006] [Indexed: 12/21/2022]
Abstract
Small endogenous RNAs such as microRNAs (miRNAs) and small interfering RNAs (siRNAs) have been found to post-transcriptionally control cellular gene networks by targeting complementary mRNAs for translation impairment (miRNA) or destruction (siRNA). We have developed a computational model, coordinated to molecular and biochemical parameters of RNA interference pathways, to provide (semi-) quantitative insight into the molecular events managing siRNA-mediated gene expression silencing in native and synthetic gene networks. Based on mass-conservation principles and kinetic rate laws, we converted biochemical RNA interference pathways into a set of ordinary differential equations that describe the dynamics of siRNA-mediated translation-regulation in mammalian cells. Capitalizing on mechanistic details of synthetic transactivator operation, we wired this model into a transcription control circuitry in which the siRNA and its target mRNA are independently regulated at the transcriptional level. In this context, we studied the impact of siRNA transcription timing on the onset of target gene transcription and production kinetics of target mRNA-encoded proteins. We also simulated the rate of siRNA-induced mRNA depletion and demonstrated that the relative concentrations of interacting siRNAs/mRNAs and the number of siRNA-specific target sites on a transcript modulate (i) the rate of target mRNA disappearance, (ii) the steady-state mRNA levels and (iii) induction dynamics of mRNA-encoded protein production. As our model predictions are consistent with available biochemical parameters, extrapolations may improve our understanding of how complex regulatory gene networks are impacted by small endogenous RNAs.
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Affiliation(s)
- Laetitia Malphettes
- Institute for Chemical and Bio-Engineering, Swiss Federal Institute of Technology-ETH Zurich, CH-8093 Zurich, Switzerland
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Samson SL, Chan L. Gene therapy for diabetes: reinventing the islet. Trends Endocrinol Metab 2006; 17:92-100. [PMID: 16504534 DOI: 10.1016/j.tem.2006.02.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Revised: 01/26/2006] [Accepted: 02/14/2006] [Indexed: 01/08/2023]
Abstract
A cure for type 1 (insulin dependent) diabetes might be found in generating surrogate insulin-producing cells to replace beta cells. A gene therapy strategy using constructs designed to allow glucose-regulated insulin transcription when delivered to non-pancreatic tissues has not fully recreated the stringent control of blood glucose provided by the beta cell. A more promising gene therapy approach has been to express pancreatic endocrine developmental factors, such as PDX-1, NeuroD/BETA2 and Neurogenin 3, to promote differentiation of non-endocrine cells towards a beta cell or islet phenotype, enabling these cells to synthesize and secrete insulin in a glucose-regulated manner. Further research is necessary, however, to better define the most effective pro-endocrine factors and the most amenable cell types to achieve transdifferentiation for beta cell replacement.
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Affiliation(s)
- Susan L Samson
- Departments of Medicine and Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Can gene therapy make pancreas and islet transplantation obsolete? Curr Opin Organ Transplant 2006. [DOI: 10.1097/01.mot.0000209297.87535.54] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Suda T, Katoh M, Hiratsuka M, Takiguchi M, Kazuki Y, Inoue T, Oshimura M. Heat-regulated production and secretion of insulin from a human artificial chromosome vector. Biochem Biophys Res Commun 2005; 340:1053-61. [PMID: 16403445 DOI: 10.1016/j.bbrc.2005.12.106] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Accepted: 12/19/2005] [Indexed: 01/28/2023]
Abstract
Human artificial chromosomes (HACs) behave as independent minichromosomes and are potentially useful as a way to achieve safe, long-term expression of a transgene. In this study, we sought to elucidate the potential of HAC vectors carrying the human proinsulin transgene for gene therapy of insulin-dependent diabetes mellitus (IDDM) using non-beta-cells as a host for the vector. To facilitate the production of mature insulin in non-beta-cells and to safely regulate the level of transgene expression, we introduced furin-cleavable sites into the proinsulin coding region and utilized the heat shock protein 70 (Hsp70) promoter. We used Cre-loxP-mediated recombination to introduce the gene cassettes onto 21DeltapqHAC, a HAC vector whose structure is completely defined, present in human fibrosarcoma HT1080 cells. We observed long-term expression and stable retention of the transgene without aberrant translocation of the HAC constructs. As expected, the Hsp70 promoter allowed us to regulate gene expression with temperature, and the production and secretion of intermediates of mature insulin were made possible by the furin-cleavable sites we had introduced into proinsulin. This study can be an initial step on the application of HAC vectors on the gene delivery to non-beta-cells, which might provide a direction for future treatment for diabetes.
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Affiliation(s)
- Tetsuji Suda
- Department of Human Genome Science, Graduate School of Medical Science, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
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Abstract
For 30 years there has been experimental work aimed at transplanting islets for the treatment of diabetes with a view to curing the disease and preventing the secondary complications. Many technical difficulties were experienced, first in isolating the islets without damaging them, and second in finding a suitable place to inject them, but until recently the results of a vascularized pancreas transplant have been superior to islet transplantation. In 2000, the group in Edmonton, headed by Shapiro, published encouraging results using a different immunosuppression in transplanting patients earlier in the course of their disease than had been attempted previously. The results were excellent at a year and good at 2 years in patients with Type I diabetes, however there was the rather worrying attrition at five years. Nevertheless, the Edmonton observations were proof of concept and have intensified interest in treating diabetes and other diseases where a specific protein synthesis was required by cell transplantation and/or genetic engineering. The recent interest in embryonic stem cells extenuated these efforts and progress is being made in defining the difficulties, which are greater than most workers would have predicted. In this review, the subject is discussed explaining where progress needs to be made in order to provide treatment that would be of value to patients.
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Affiliation(s)
- Roy Calne
- Department of Surgery, Addenbrooke's Hospital, Cambridge, UK.
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