This site is intended for healthcare professionals only

Cell-based therapies for the management of type 1 diabetes

Peter C Hindmarsh, Catherine Peters

Pancreatic or islet cell transplantation are well-established options for the management of type 1 diabetes. Their use in paediatric practice has been limited to islet cell auto- transplants following chronic pancreatitis. The need for ongoing immunosuppression limits the broader use of these therapeutic approaches in the management of children with type 1 diabetes. Donor supply of islets for transplantation remains the biggest limitation for the broader application of these techniques. Better, milder immunosuppression regimens coupled with alternative sources for islets and improved in-situ protection of the graft are options for further development. Embryonic stem cells may provide a source for beta-cells ultimately, but the development of a functioning islet remains elusive.

Type 1 diabetes is a T-cell-mediated autoimmune disease in which beta-cells are destroyed. Clinical signs arise when the autoimmune process exceeds the regenerative capacity of the beta-cells, leading to a critical reduction in cell numbers and insulin production.

Intensive insulin therapy delivered by injection or an insulin pump is the mainstay of therapy for type 1 diabetes. Tight glycaemic control to minimise the long-term micro- and macrovascular complications is the primary therapeutic goal (DCCT/EDIC [Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications] Research Group, 2009). While such interventions are effective, normalisation of HbA1c is rarely achieved without the ever-present risk of hypoglycaemia, which is the main limitation to tight glycaemic control (Cryer, 2009). 

Transplantation therapies for type 1 diabetes have largely centred on either solid organ transplantation or islet cell transplantation: whole pancreas transplantation is usually undertaken either alone or in combination with a kidney; and islet cell transplantation can be allogenic or an auto-transplant. Recent developments in the understanding of autoimmune diseases coupled with advances in stem cell biology have opened up new avenues for cell-based therapies in type 1 diabetes. 

In this article the authors examine the current cell-based technologies. Although the introduction of these approaches to the standard clinical care of children and young people with type 1 diabetes is some way off, paediatric diabetologists need to begin to familiarise themselves with the concepts and methodologies in order to better provide future care for children and young people with type 1 diabetes.

Solid organ transplantation
The replacement of the whole pancreas has a long history, and current success rates are depicted in Figure 1; most recipients also receive a renal transplant for diabetic nephropathy. Graft survival of a pancreas transplant following renal transplantation is better than pancreas alone or pancreas first followed by kidney. Over an 11–20-year follow-up, HbA1c was shown to normalise at a mean of 5.3% (34 mmol/mol) and diabetic nephropathy reversed after 10 years (Gruessner et al, 2008). Solid organ transplantation success rates provide a useful benchmark against which cell-based therapies can be compared.

In paediatric practice, solid organ transplantation is unlikely to be a major option because of the intense immunosuppression required. Nonetheless, it might be worth considering in a child or young person with type 1 diabetes when renal transplantation for other reasons is considered.

Islet cell transplantation
Auto- or allogenic islet transplantation represents a minimally invasive approach to beta-cell replacement. Auto-transplantation is used in situations where pancreatic function becomes compromised or surgical removal is contemplated, such as chronic pancreatitis or benign pancreatic endocrine tumours. Post-pancreatectomy diabetes is hard to control with exogenous insulin, so transplantation is a valuable intervention.

Reported complications relate to the pancreatectomy rather than the transplant itself. The isolated islet cells are infused directly into the hepatic portal vein. The total number of islets required, 7000/kg in adults and 4000/kg in children, is less than allogenic transplantation. The islets need 3–6 months to establish in the liver, and during this time tight glycaemic control with insulin is recommended to protect the cells from glucotoxicity. 

Success rates of insulin independence vary, with the large Minnesota series reporting 45% of recipients insulin independent after 1 year, with a mean HbA1c of 4.6%, and a further 16% requiring only once-daily, low-dose insulin; at 3 years post-transplant, 30% remained insulin independent (Sutherland et al, 2012). The intervention is suited to children, and in the Minnesota series of 409 recipients, 53 were children aged 5–18 years. Children seemed to do better in terms of insulin independence, with 55% independent at 3 years. Islet yield correlated with the degree of pancreatic function before pancreatectomy, and also to the number of previous surgical interventions for pancreatitis.

Allogenic pancreatic islet cell transplantation for type 1 diabetes shows clear short- and long-term efficacy. This procedure has been reserved for those individuals with recurrent, severe hypoglycaemia or marked glycaemic lability, or both, as well as those already on immunosuppression after renal transplantation (NICE, 2008). Since the publication of the Edmonton experience in 2000 (Shapiro et al, 2000), a total of 677 islet-alone or islet-after-kidney transplants have been recorded in the Collaborative Islet Transplant Registry (Barton et al, 2012).

Insulin independence at 3 years from transplant increased over the period 1999 to 2010, from 27% to 44%, with a concomitant reduction in HbA1c and resolution of severe hypoglycaemia. The increased graft survival rate and insulin independence compare favourably with the 61% insulin independence following pancreas-alone transplantation (Gruessner et al, 2008). Current insulin independence rates for islet cell transplantation are similar to those achieved with pancreas-alone transplantation in the 1990s (Figure 1). 

Two key components of this success have been the collagenase enzymes used for islet digestion and novel protocols using T-cell depletion for induction with tumour necrosis factor-alpha inhibitors (Hering et al, 2005; Bellin et al, 2008), which has led to a reduction in the reinfusion rate to 48%. As with pancreas transplantation, use of the calcineurin inhibitor tacrolimus in low doses was not associated with the beta-cell toxicity observed at higher doses.

The cell-dosing schedule is 15000/kg, which is about a quarter of that used in 1999 but twice that used in auto-transplants; the factors influencing islet yields and loss post-transplantation are shown in Box 1. Nonetheless, the numbers needed if islet cell transplantation is to become more mainstream as a therapy still requires a major commitment to donor recruitment as well as increasing tissue availability more specifically, and at the same time reducing allograft rejection (Box 2). 

Islet transplantation from a live related donor after selective pancreatic resection successfully ameliorates brittle diabetes with hypoglycaemia (Matsumoto et al, 2005). However, this clearly places the donor at risk of major complications, including diabetes, in addition to the immunosuppressive side effects in the recipient.

Attempts to overcome the host’s immune system by encapsulating islets in a semipermeable membrane through which nutrients and insulin can pass, but larger T- and B-cells cannot, has had limited success (Soon-Shiong et al, 1994; Elliot et al, 2007). The survival of the graft remains limited, with challenges surrounding the selection of the optimal encasing biomaterial. 

It has also been suggested that alternative siting of transplanted islets may improve survival by reducing the blood-mediated inflammatory response. In cases of pancreatectomy, there may be advantages in placing autologous islets in an alternative site, such as muscle (Rafael et al, 2008).

Side effects of islet transplantation relate predominantly to the infusion procedure, particularly portal vein thrombosis or intraperitoneal bleeding. Short-term immunosuppression problems occur in up to 30% of cases (www.citregistry.org), but long-term safety data need to be acquired. There remains, however, a careful balance to be struck between establishing excellent glucose control and cessation of disabling hypoglycaemia and the long-term effects of chronic immunosuppression. Until milder immunosuppression regimens are developed and the donor recruitment issue resolved, the use of allogenic islet transplantation in children and young people will remain limited.

Strategies for increasing available cells for transplantation
Embryonic stem cells
Embryonic stem cells (ESCs) derived from the inner cell mass of blastocysts during the early stages of embryogenesis are pluripotent. As the steps of differentiation to a beta-cell are well understood (Guo and Hebrok, 2009), ESCs could provide a source for the large number of cells needed for transplantation. However, it has to be appreciated that directed differentiation of ESCs is challenging, not least because large cell-number generation has to be balanced against the formation of unwanted cell types or fates.

Initial attempts to generate beta-cells from ESCs were only partially successful as the confirmation that true conversion to a physiological beta-cell was often lacking. This is important as cells other than beta-cells can produce insulin, such as foetal hepatocytes. Also, ESC-derived beta-like cells generally secrete insulin at much lower levels and are less well regulated than true beta-cells.

Directed differentiation of human ESCs has been more successful (Kroon et al, 2008). The steps mimic those observed in normal pancreas development using signals that regulate embryonic endoderm and pancreas formation. Implantation of human ESC-derived endocrine precursors results in insulin-positive cells that reduce hyperglycaemia in mouse models of diabetes, whereas removal of the cells leads to recurrence of the diabetes. These approaches have been advanced further by careful coordination in a temporal and spatial manner of the interaction of the right combination of transcription factors. For example, too early expression of the transcription factor neurogenin 3 results in dominant formation of alpha-cells to the detriment of other cell types (Johansson et al, 2007).

Despite these major advances, the cells obtained probably represent immature beta-cells with low insulin content and numerous other hormones in the same cell, as well as little response to glucose stimulation (Jiang et al, 2007). One reason for this may be that proper cell–cell interactions are not facilitated. Pancreas development is interactive with different layers secreting and responding to inductive signalling. Islets are complex three-dimensional structures consisting of different cell types and different hormones that interact closely with blood vessels and the nervous system. Co-culturing islets with mesenchymal stem cells in mice has been demonstrated to improve islet survival through direct contact or soluble mediators and is a promising new area of research (Rackham et al, 2013). Three further areas need to be explored:

  • First, consideration needs to be given to the risk of tumour formation; undifferentiated ESCs associated with transplantation could lead to teratoma formation. 
  • Second, the ongoing immune process that causes type 1 diabetes along with the immune response to administered stem cells will probably require concomitant immunosuppression. 
  • Third, the pluripotential cell source needs to be considered; only four transcription factors are required to reprogramme somatic cells into induced pluripotent stem cells that can differentiate into all three germ layers (Park et al, 2008). Initial studies used viral transfection, which is problematic, but more recent studies have used small chemicals or histone deacetylase inhibitors to induce reprogramming (Huangfu et al, 2008).

Expanding endogenous beta-cell mass
It is well known that conditions such as pregnancy lead to an expansion in beta-cell mass. New beta-cells are thought to arise predominantly from existing beta-cells, with a smaller contribution from cells located in the pancreatic duct (Dor et al, 2004). The cell source probably depends upon the stimulus applied; regeneration after injury tends to be mainly from duct lining cells. Transdifferentiation of pancreatic exocrine cells or hepatic stem cells into beta-cells has been demonstrated using three transcription factors from the beta-cell differentiation pathway. Despite these advances it remains difficult ex vivo to expand the number of beta-cells and to maintain insulin expression over time.

Xenotransplantation
Xenotransplantation with pig islets would potentially overcome the problem of demand for islets, with an unlimited supply from colonies of isolated, disease-free herds. In addition, the use of transgenic pigs enables specific manipulation of beta-cells to ameliorate immune rejection and blood inflammatory responses (Ekser et al, 2012). Small human trials are ongoing (Elliot et al, 2007; Garkavenko et al, 2012), but rejection remains a problem.

Immunotherapies
There is increasing evidence to suggest that once the autoimmune process has been attenuated using non-diabetogenic means, beta-cell regeneration can take place even in the face of clinical manifestations of the disease (Hess et al, 2003). Several approaches have been used in humans and mice. 

Autologous non-myeloablative haematopoietic stem-cell transplantation has been used to treat a variety of autoimmune conditions (Farge et al, 2010), and several groups have reported successful short-term outcomes in type 1 diabetes (Couri et al, 2009; Snarski et al, 2011). Most recipients are insulin-free immediately after transplantation, with approximately 50% insulin-free 19–31 months later (Gu et al, 2012).

Hospital stays average between 18–25 days, and preconditioning requires cyclophosphamide and anti-thymocyte globulin. Alopecia, nausea and bone marrow suppression are immediate side-effects. Long-term complications related to immunosuppression therapy, such as tumour formation, endocrine disorders (hypothyroidism) and infertility, remain to be defined. Older age at onset and absence of diabetic ketoacidosis at presentation are prognostic factors for success. For the paediatric population, who tend to be younger and present more often with ketoacidosis, this approach may be less attractive, particularly when considering the risk–benefits of immunosuppression.

Current animal models offer other approaches that may obviate the need for transplantation. In non-obese diabetic mice, multiple injections of male allogenic splenocytes enables the recovery of beta-cell mass that arises from beta-cell precursors and is not related directly to the splenocyte injections (Nishio et al, 2006). This observation may translate into a more refined immunomodulation than that provided by autologous non-myeloablative haematopoietic stem-cell transplantation. Although the initial immunotherapy clinical trials are not as promising (Ludvigsson et al, 2012), autologous T-regulatory cell infusion for children and young people newly diagnosed with type 1 diabetes may be an option (Marek-Trzonkowska et al, 2012).

Conclusion
There is a clear effect of solid organ and auto-islet transplantation. Exploration of other sources, such as stem cells or capitalising on known pathways of proliferation, is required as there is likely to be a steady increase in the number of islet cell transplantations undertaken in individuals with type 1 diabetes. Any approach will have to meet high safety standards and show that the derived beta-cells secrete insulin in response to glucose in a physiological manner. This will need to be coupled with more specific immunotherapies directed towards the autoimmune process in type 1 diabetes.

REFERENCES:

Barton FB, Rickels MR, Alejandro R et al (2012) Improvement in outcomes of clinical islet transplantation: 1999–2010. Diabetes Care 35: 1436–45
Bellin MD, Kandaswamy R, Parkey J et al (2008) Prolonged insulin independence after islet allotransplants in recipients with type 1 diabetes. Am J Transplant 8: 2463–70
Couri CE, Oliveira MC, Stracieri AB et al (2009) C-peptide levels and insulin independence following autologous non-myeloablative haematopoietic stem cell transplantation in newly diagnosed type 1 diabetes mellitus. JAMA 301: 1573–9
Cryer PE (2009) Hypoglycaemia in Diabetes. American Diabetes Association, Alexandria: 9–10
Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Research Group (2009) Modern-day clinical course of type 1 diabetes mellitus after 30 years’ duration. Arch Int Med 169: 1307–16
Dor Y, Brown J, Martinez OI, Melton DA (2004) Adult pancreatic beta-cells are formed by self-duplication rather than stem-cell differentiation. Nature 429: 41–6
Ekser B, Ezzelarab M, Hara H et al (2012) Clinical xenotransplantation: The next medical revolution? Lancet 379: 672–83
Elliott RB, Escobar L, Tan PL et al (2007) Live encapsulated porcine islets from a type 1 diabetic patient 9.5 years after xenotransplantation. Xenotransplantation 14: 157–61
Farge D, Labopin M, Tyndall A et al (2010) Autologous haematopoietic stem-cell transplantation for autoimmune diseases: An observation study on 12 years’ experience from the European Group for Blood and Marrow Transplantation Working Party on Autoimmune Diseases. Haematologica 95: 284–92
Garkavenko O, Wynyard S, Nathu D et al (2012) The first clinical xenotransplantation trial in New Zealand: Efficacy and safety. Xenotransplantation 19: 2–22
Gruessner RW, Sutherland DE, Kandaswamy R, Gruesner AC (2008) Over 500 solitary pancreas transplants in non-uraemic patients with brittle diabetes mellitus. Transplantation 85: 42–7
Gu W, Hu J, Wang W et al (2012) Diabetic ketoacidosis at diagosis influences complete remission after treatment with haematopoietic stem-cell transplantation in adolescents with type 1 diabetes. Diabetes Care 35: 1413–9
Guo T, Hebrok M (2009) Stem cells to pancreatic beta-cells: New sources for diabetes cell therapy. Endocr Rev 30: 214–27
Hering BJ, Kandaswamy R, Ansite JD et al (2005) Single donor marginal dose islet transplantation in patients with type 1 diabetes. JAMA 293: 830–5
Hess D, Li L, Martin M et al (2003) Bone marrow derived stem cells initiate pancreatic regeneration. Nat Biotechnol 21: 763–70
Huangfu D, Maehr R, Guo W et al (2008) Induction of pluripotent stem cells by defined factors is greatly improved by small-molecule compounds. Nat Biotechnol 26: 795–7
Jiang W, Shi Y, Zhao D et al (2007) In-vitro derivation of functional insulin-producing cells from human embryonic stem cells. Cell Res 17: 333–44
Johansson KA, Dursun U, Jordan N et al (2007) Temporal control of neurogenin3 activity in pancreas progenitors reveals competence windows for the generation of different endocrine cell types. Dev Cell 12: 457–65
Kroon E, Martinson LA, Kadoya K et al (2008) Pancreatic endoderm derived from human embryonic stem cells generates glucose-responsive insulin-secreting cells in vivo. Nat Biotechnol 26: 443–52
Ludvigsson J, Krisky D, Casas R et al (2012) GAD65 antigen therapy in recently diagnosed type 1 diabetes mellitus. N Engl J Med 366: 433–42
Marek-Trzonkowska N, Mysliwiec M, Dobyszuk A et al (2012) Administration of CD4+CD25highCD127-regulatory T-cells preserves beta-cell function in type 1 diabetes in children. Diabetes Care 35: 1817–20
Matsumoto S, Okitsu T, Iwanaga Y et al (2005) Insulin independence of unstable diabetic patient after single living donor islet transplantation. Transplant Proc 37: 3427–9
NICE (2008) Allogeneic Pancreatic Islet Cell Transplantation for Type 1 Diabetes Mellitus. Interventional Procedure Guideline 257. Available at: www.nice.org.uk/IPG257 (accessed 25.01.13)
Nishio J, Gaglia JL, Turvey SE et al (2006) Islet recovery and reversal of murine type 1 diabetes in the absence of any infused spleen cell contribution. Science 311: 1775–8
Park IH, Zhao R, West JA et al (2008) Reprogramming of human somatic cells to pluripotency with defined factors. Nature 451: 141–6
Rackham CL, Dhadda PK, Chagastelles PC et al (2013) Pre-culturing islets with mesenchymal stem cells using a direct contact configuration is beneficial for transplantation outcome in diabetic mice. Cytotherapy 15: [Epub ahead of print]
Rafael E, Tibell A, Rydén M et al (2008) Intramuscular autotransplantation of pancreatic islets in a 7-year-old child: A 2-year follow-up. Am J Transplant 8: 458–62
Shapiro AM, Lakey JR, Ryan EA et al (2000) Islet transplantation in seven patients with type 1 diabetes mellitus using a glucocorticoid-free immunosuppressive regimen. N Engl J Med 343: 230–8
Snarski E, Havrdova T, Boucek P et al (2011) Independence of exogenous insulin following immunoablation and stem cell reconstitution in newly diagnosed diabetes type 1. Bone Marrow Transplant 46: 562–6
Soon-Shiong P, Heintz RE, Merideth N et al (1994) Insulin independence in a type 1 diabetic patient after encapsulated islet transplantation. Lancet 343: 950–1
Sutherland DE, Radosevich DM, Bellin MD et al (2012) Total pancreatectomy and islet autotransplantation for chronic pancreatectomy. JAMA 214: 409–24
US Department of Health and Human Services (2011) OPTN/SRTR Annual Report 2011. Health Resources and Services Administration. Available at: http://optn.transplant.hrsa.gov/data/annualreport.asp (accessed 25.1.13)

For the latest news and articles

Sign up to all DiabetesontheNet journals

© Copyright Omniamed Communications. All Rights Reserved​
108 Cannon Street, London, EC4N 6EU. Registered in the United Kingdom​
Omniamed logo white
Free for all UK & Ireland healthcare professionals

Sign up to all DiabetesontheNet journals

 

By clicking ‘Subscribe’, you are agreeing that DiabetesontheNet.com are able to email you periodic newsletters. You may unsubscribe from these at any time. Your info is safe with us and we will never sell or trade your details. For information please review our Privacy Policy.

DiabetesontheNet Logo

This website is for healthcare professionals only. To continue, please confirm that you are a healthcare professional below.