Regeneration therapy for diabetes mellitus

Oreocnide integrifolia Flavonoids Augment Reprogramming for Islet Neogenesis and β-Cell Regeneration in Pancreatectomized BALB/c Mice

Agents which can either trigger proliferation of β-cells or induce neogenesis of β-cells from precursors would be of pivotal role in reversing diabetic manifestations. We examined the role of flavonoid rich fraction (FRF) of Oreocnide integrifolia leaves using a mice model of experimental regeneration. BALB/c mice were subjected to ~70% pancreatectomy (Px) and supplemented with FRF for 7, 14, and 21 days after pancreatectomy. Px animals displayed increased blood glucose levels and decreased insulin titres which were ameliorated by FRF supplementation. FRF-treated mice demonstrated prominent newly formed islets budding off from ducts and depicting increased BrdU incorporation. Additionally, transcripts levels of Ins1/2, Reg-3α/γ, Ngn-3, and Pdx-1 were upregulated during the initial 1 week. The present study provides evidence of a nutraceutical contributing to islet neogenesis from ductal cells as the mode of β-cell regeneration and a potential therapeutic for clinical trials in management of diabetic manifestations.

Gene-delivery systems for iPS cell generation

IMPORTANCE OF THE FIELD

Induced pluripotent stem (iPS) cells offer extraordinary promise for regenerative medicine applications, and provide new opportunities for use in disease modeling, drug screening and drug toxicology. AREAS COVED IN THIS REVIEW: iPS cell technology is still in its infancy. In this review article, we present a comprehensive survey of reprogramming approaches focusing on gene-delivery systems used for generation of iPS cells from somatic cells, categorize gene-delivery vectors, and discuss their advantages and limitations for somatic cell reprogramming. We include pertinent literature published between 2006 and the present.

WHAT THE READER WILL GAIN

Although iPS cell technology has been improved via the use of various gene-delivery vectors, it still suffers from either low reprogramming efficiency or too many genomic modification steps. Extensive work is still required to improve current vectors or explore new vectors for effectively reprogramming human somatic cells into iPS cells, with or without minimal genomic modification steps.

TAKE HOME MESSAGE

A single non-integrating reprogramming vector system with high reprogramming efficiency is probably essential for generation of clinically translatable human iPS cells.

Recovery of islet beta-cell function in streptozotocin- induced diabetic mice: an indirect role for the spleen

Limitations in islet beta-cell transplantation as a therapeutic option for type 1 diabetes have prompted renewed interest in islet regeneration as a source of new islets. In this study we tested whether severely diabetic adult C57BL/6 mice can regenerate beta-cells. Diabetes was induced in C57BL/6 mice with high-dose streptozotocin (160-170 mg/kg). In the absence of islet transplantation, all diabetic mice remained diabetic (blood glucose >400 mg/dl), and no spontaneous reversal of diabetes was observed. When syngeneic islets (200/mouse) were transplanted into these diabetic mice under a single kidney capsule, stable restoration of euglycemia for >/=120 days was achieved. Removal of the kidney bearing the transplanted islets at 120 days posttransplantation revealed significant restoration of endogenous beta-cell function. This restoration of islet function was associated with increased beta-cell mass, as well as beta-cell hypertrophy and proliferation. The restoration of islet cell function was facilitated by the presence of a spleen; however, the facilitation was not due to the direct differentiation of spleen-derived cells into beta-cells. This study supports the possibility of restoring beta-cell function in diabetic individuals and points to a role for the spleen in facilitating this process.

Existence of islet regenerating factors within the pancreas

Reduction in the functional mass of beta-cells is a common denominator in most forms of diabetes. Since the replicative potential of beta-cells is limited, the search for factors that trigger islet neogenesis becomes imperative. Here we tested the hypothesis that regenerating factors for the pancreas are either secreted by or present within the pancreatic milieu itself. For this purpose, we intraperitoneally injected pancreatic cell culture supernatant (PCCS), from normal pancreas, into streptozotocin (STZ)-induced diabetic mice for 15 consecutive days. The PCCS-treated mice showed sustained reversal in 77.77% of experimental diabetic mice as evidenced by restoration of normoglycemia, increase in serum insulin levels and occurrence of neo islets in histopathological studies during a two month follow up, as opposed to the control diabetic mice which remained hyperglycemic throughout. In order to examine the potential of PCCS to bring about the regeneration of islets, we treated intra-islet precursor cells with PCCS in vitro, which led to the neogenesis of islets as evidenced by dithiozone and insulin immunostaining. These findings substantiate our hypothesis and make the search for regenerative factors converge towards the pancreas and its immediate surroundings. Such regenerative approaches, in combination with other therapeutic strategies to promote islet neogenesis may, in future, provide a cure and/or better means for the control and management of diabetes.