Stem cells therapy for type 1 diabetes

Inducing Specific Immune Tolerance to Prevent Type 1 Diabetes in NOD Mice

OBJECTIVES

Proinsulin is the first autoantigen in type 1 diabetes (T1D). We reasoned that coupling hematopoietic stem cells (HSCs) transplantation with ex vivo transduction of syngeneic HSCs with lentiviral vectors to express proinsulin II could prevent T1D in nonobese diabetic (NOD) mice.

METHODS

Hematopoietic stem cells were isolated from 6- to 8-week-old NOD female mice and transduced in vitro with lentiviral vectors encoding proinsulin II. Preconditioned 3- to 4-week-old female NOD mice were transplanted with transduced or nontransduced HSCs and compared with age-matched unmanipulated control. The insulitis, T1D development, and immune reconstitution were assessed.

RESULTS

The mean (SD) insulitis score was significantly reduced (1.156 [0.575] vs 2.156 [0.892] or 3.043 [0.728], P = 0.009 or <0.001), and diabetes was nearly completely prevented (1/13 vs 5/12 or 4/9, P = 0.031 or 0.013) in recipients of transduced HSCs expressing proinsulin II as compared with recipients of nontransduced HSCs or unmanipulated control. Sialitis, reconstitution of peripheral blood leukocytes, and in vitro recall responses to ovalbumin were not different between 3 groups of mice.

CONCLUSIONS

Syngeneic transplantation of HSCs transduced ex vivo with lentiviral vectors to encode proinsulin II is a novel strategy to prevent T1D.

Mesenchymal stem cells derived in vitro transdifferentiated insulin-producing cells: A new approach to treat type 1 diabetes

The pathophysiology of type 1 diabetes mellitus (T1DM) is largely related to an innate defect in the immune system culminating in a loss of self-tolerance and destruction of the insulin-producing β-cells. Currently, there is no definitive cure for T1DM. Insulin injection does not mimic the precise regulation of β-cells on glucose homeostasis, leading long term to the development of complications. Stem cell therapy is a promising approach and specifically mesenchymal stem cells (MSCs) offer a promising possibility that deserves to be explored further. MSCs are multipotent, nonhematopoietic progenitors. They have been explored as an treatment option in tissue regeneration as well as potential of in vitro transdifferentiation into insulin-secreting cells. Thus, the major therapeutic goals for T1DM have been achieved in this way. The regenerative capabilities of MSCs have been a driving force to initiate studies testing their therapeutic effectiveness; their immunomodulatory properties have been equally exciting; which would appear capable of disabling immune dysregulation that leads to β-cell destruction in T1DM. Furthermore, MSCs can be cultured under specially defined conditions, their transdifferentiation can be directed toward the β-cell phenotype, and the formation of insulin-producing cells (IPCs) can be targeted. To date, the role of MSCs-derived IPC in T1DM–a unique approach with some positive findings–have been unexplored, but it is still in its very early phase. In this study, a new approach of MSCs-derived IPCs, as a potential therapeutic benefit for T1DM in experimental animal models as well as in humans has been summarized.

Functions and roles of proteins: diabetes as a paradigm

Molecular and cellular biology has moved towards complete and accurate knowledge of how molecules behave in space and time. Protein is considered as the primary group of molecules responsible for mediating most physiological processes. Changes in the levels of proteins may lead to the altered function and are responsible for many diseases. This review provides a partial molecular explanation of biological force-ratio generation that may act to split protein into branches, and shows molecular functional divergence. Developing a non-reductionist theory of the cellular function in medicine is clearly not sufficient. Finding effective parameters of the models by characterizing molecular interactions becomes necessary. Protein interactivity and stability provides a basis for an integrated understanding of pathologies such diabetes. One example of how a mechanistic analysis of such physiological processes can be of value is the time-delay between mRNA and translation that can act as a fork allowing a slowdown in gene expression.

Improvement of pig islet function by in vivo pancreatic tissue remodeling: a "human-like" pig islet structure with streptozotocin treatment

Pig islets demonstrate significantly lower insulin secretion after glucose stimulation than human islets (stimulation index of ∼12 vs. 2 for glucose 1 and 15 mM, respectively) due to a major difference in β- and α-cell composition in islets (60% and 25% in humans and 90% and 8% in pigs, respectively). This leads to a lower rise in 3',5'-cyclic adenosine monophosphate (cAMP) in pig β-cells. Since glucagon is the major hormonal effector of cAMP in β-cells, we modified pig islet structure in vivo to increase the proportion of α-cells per islet and to improve insulin secretion. Selected doses (0, 30, 50, 75, and 100 mg/kg) of streptozotocin (STZ) were intravenously injected in 32 young pigs to assess pancreatic (insulin and glucagon) hormone levels, islet remodeling (histomorphometry for α- and β-cell proportions), and insulin and glucagon secretion in isolated islets. Endocrine structure and hormonal content of pig islets were compared with those of human islets. The dose of STZ was significantly correlated with reductions in pancreatic insulin content (p< 0.05, r(2) = 0.77) and the proportion of β-cells (p < 0.05, r(2) = 0.88). A maximum of 50 mg/kg STZ was required for optimal structure remodeling, with an increased proportion of α-cells per islet (26% vs. 48% α-cells per islet for STZ <50 mg/kg vs. >75 mg/kg; p < 0.05) without β-cell dysfunction. Three months after STZ treatment (30/50 mg/kg STZ), pig islets were isolated and compared with isolated control islets (0 mg/kg STZ). Isolated islets from STZ-treated (30/50 mg/kg) pigs had a higher proportion of α-cells than those from control animals (32.0% vs. 9.6%, respectively, p < 0.05). After in vitro stimulation, isolated islets from STZ-treated pigs demonstrated significantly higher glucagon content (65.4 vs. 21.0 ng/ml, p < 0.05) and insulin release (144 µU/ml) than nontreated islets (59 µU/ml, p < 0.05), respectively. Low-dose STZ (<50 mg/kg) can modify the structure of pig islets in vivo and improve insulin secretion after isolation.

Effect of transplantation of mesenchymal stem cells induced into early hepatic cells in streptozotocin-induced diabetic mice

Cellular replacement therapy for diabetes mellitus has received much attention. In this study we investigated the effect of transplantation of bone marrow-derived mesenchymal stem cells (BM-MSCs) induced into endoderm and early hepatic cells in streptozotocin (STZ)-induced diabetic mice. Mouse BM-MSCs were cultured in the presence of hepatocyte growth factor (HGF) and fibroblast growth factor (FGF-4) for 2 weeks and transplanted into diabetic mice. Blood glucose levels, intraperitoneal glucose tolerance test, serum insulin, body weight and islets histology were analyzed. The results demonstrated that transplantation of syngeneic induced MSCs could reverse STZ-induced diabetes in mice. The treatment of mice with hyperglycemia and islet destruction resulted in the repair of pancreatic islets. Blood glucose levels, intraperitoneal glucose tolerance test, and serum insulin were significantly recovered in induced BM-MSCs (iBM-MSCs) group. In addition, in the iBM-MSCs group the body weight and the number of islets were significantly increased compared to other groups. The results demonstrate that BM-MSCs induced into endoderm and early hepatic cells are suitable candidates for cell-based therapy of diabetes mellitus.

Tissue-derived stem and progenitor cells

The characterization and isolation of various stem cell populations, from embryonic through tissue-derived stem cells, have led a rapid growth in the field of stem cell research. These research efforts have often been interrelated as to the markers that identify a select cell population are frequently analyzed to determine their expression in cells of distinct organs/tissues. In this review, we will expand the current state of research involving select tissue-derived stem cell populations including the liver, central nervous system, and cardiac tissues as examples of the success and challenges in this field of research. Lastly, the challenges of clinical therapies will be discussed as it applies to these unique cell populations.

Mesenchymal stem cells: Stem cell therapy perspectives for type 1 diabetes

Mesenchymal stem cells (MSCs) are multipotent non-haematopoietic progenitor cells that are being explored as a promising new treatment for tissue regeneration. Although their immunomodulatory properties are not yet completely understood, their low immunogenic potential together with their effects on immune response make them a promising therapeutic tool for severe refractory autoimmune diseases. Type 1 diabetes is characterized by T cell-mediated autoimmune destruction of pancreatic beta cells. While insulin replacement represents the current therapy for type 1 diabetes, its metabolic control remains difficult, as exogenous insulin cannot exactly mimic the physiology of insulin secretion. Pancreatic or islet transplantation can provide exogenous insulin independence, but is limited by its intrinsic complications and the scarcity of organ donors. In this context, stem cell therapy, based on the generation of insulin-producing cells (IPCs) derived from MSCs, represents an attractive possibility. In this review, we provide a brief characterization of MSC immunomodulatory effects, and present the current experimental evidence for the potential therapeutic efficacy of MSC transplantation in diabetes.

New potential treatments for protection of pancreatic B-cell function in Type 1 diabetes

Type 1 diabetes mellitus results from the progressive and specific autoimmune destruction of insulin-secreting pancreatic B-cells, which develops over a period of years and continues after the initial clinical presentation. The ultimate goal of therapeutic intervention is prevention or reversal of the disease by the arrest of autoimmunity and by preservation/restoration of B-cell mass and function. Recent clinical trials of antigen-specific or non-specific immune therapies have proved that modulation of islet specific autoimmunity in humans and prevention of insulin secretion loss in the short term after the onset of disease is achievable. The identification of suitable candidates for therapy, appropriate dosage and timing, specificity of intervention and the side-effect profile are crucial for the success of any approach. Considering the complexity of the disease, it is likely that a rationally designed approach of combined immune-based therapies that target suppression of B-cell specific autoreactivity and maintenance of immune tolerance, coupled with islet regeneration or replacement of the destroyed B-cell mass, will prove to be most effective in causing remission/reversal of disease in a durable fashion.

Recent progress on tissue-resident adult stem cell biology and their therapeutic implications

Recent progress in the field of the stem cell research has given new hopes to treat and even cure diverse degenerative disorders and incurable diseases in human. Particularly, the identification of a rare population of adult stem cells in the most tissues/organs in human has emerged as an attractive source of multipotent stem/progenitor cells for cell replacement-based therapies and tissue engineering in regenerative medicine. The tissue-resident adult stem/progenitor cells offer the possibility to stimulate their in vivo differentiation or to use their ex vivo expanded progenies for cell replacement-based therapies with multiple applications in human. Among the human diseases that could be treated by the stem cell-based therapies, there are hematopoietic and immune disorders, multiple degenerative disorders, such as Parkinson's and Alzheimer's diseases, type 1 or 2 diabetes mellitus as well as eye, liver, lung, skin and cardiovascular disorders and aggressive and metastatic cancers. In addition, the genetically-modified adult stem/progenitor cells could also be used as delivery system for expressing the therapeutic molecules in specific damaged areas of different tissues. Recent advances in cancer stem/progenitor cell research also offer the possibility to targeting these undifferentiated and malignant cells that provide critical functions in cancer initiation and progression and disease relapse for treating the patients diagnosed with the advanced and metastatic cancers which remain incurable in the clinics with the current therapies.

Promoting ectopic pancreatic fates: pancreas development and future diabetes therapies

Diabetes is a disease that could be treated more effectively with a better understanding of pancreas development. This review examines the role of master regulator genes driving crucial steps in pancreas development, from foregut specification to differentiation of the five endocrine cell types. The roles of Pdx1, Ptf1a, and Ngn3 are particularly examined as they are both necessary and sufficient for promoting pancreatic cell fates (Pdx1, Ptf1a) and endocrine cell development (Ngn3). The roles of Arx and Pax4 are studied as they compose part of the regulatory mechanism balancing development of different types of endocrine cells within the iselts and promote the development of alpha/PP and beta/delta cell progenitors, respectively. The roles of the aforementioned genes, and the consequences of misexpression of them for functionality of the pancreas, are examined through recent studies in model organisms, particularly Xenopus and zebrafish. Recent developments in cell replacement therapy research are also covered, concentrating on stem cell research (coaxing both adult and embryonic stem cells toward a beta cell fate) and transdifferentiation (generating beta cells from other differentiated cell types).

Cellular therapies for type 1 diabetes

Type 1 diabetes mellitus (T1DM) is a disease that results from the selective autoimmune destruction of insulin-producing beta-cells. This disease process lends itself to cellular therapy because of the single cell nature of insulin production. Murine models have provided opportunities for the study of cellular therapies for the treatment of diabetes, including the investigation of islet transplantation, and also the possibility of stem cell therapies and islet regeneration. Studies in islet transplantation have included both allo- and xeno-transplantation and have allowed for the study of new approaches for the reversal of autoimmunity and achieving immune tolerance. Stem cells from hematopoietic sources such as bone marrow and fetal cord blood, as well as from the pancreas, intestine, liver, and spleen promise either new sources of islets or may function as stimulators of islet regeneration. This review will summarize the various cellular interventions investigated as potential treatments of T1DM.