Autophagy stimulated proliferation of porcine PSCs might be regulated by the canonical Wnt signaling pathway.

Porcine pancreatic stem cells (PSCs) are one kind of the potential cells for treatment of human diabetes. Autophagy is a highly conserved cellular degradation process in which it helps to maintain the balance between the synthesis, degradation and subsequent recycling of cellular components. However, how autophagy contributes to PSCs has not yet been investigated. Here, we established GFP-LC3 transfected porcine PSC lines in which the accumulation of autophagosomes can be efficiently visualized to evaluate the autophagic activity. Moreover, we observed that starved PSCs which showed increased autophagic activity exhibited an increased tendency to proliferate through the results of BrdU, flow cytometry and western blotting. Furthermore, increased expression of active ß-catenin after inducing autophagy indicated that it might be the canonical Wnt signaling that autophagy activated to exert the function on the stimulation of PSCs proliferation. Collectively, these results demonstrated that autophagy stimulated proliferation of PSCs might be regulated by the canonical Wnt signaling pathway. Our results for the first time shed light on a role of autophagy for stimulating the proliferation of porcine PSCs.

Canonical Wnt signaling pathway contributes to the proliferation and survival in porcine pancreatic stem cells (PSCs).

Pancreatic stem cells (PSCs) transplantation is a potential therapeutic approach to type 1 diabetes mellitus (D1M). However, before clinical use, there are some major hurdles to be faced that need to be comprehensively considered and given some potential solutions in vitro. Human PSCs are difficult to obtain and have a short replicative senescence. As an alternative, we instead established porcine PSCs; as insulin is highly conserved and physiological glucose levels are similar between human and porcine. In order to solve the problems during transplantation therapy, such as the need for an enormous amount of PSCs and good cell survival in overactive autoimmunity induced by reactive oxygen cpecies (ROS) in D1M patients, we utilized Wnt3a overexpression to activate the canonical Wnt signaling pathway in PSCs. We found that the expression of proliferation genes, such as c-Myc, was up-regulated as the downstream of ß-catenin, which promoted the PSCs proliferation and made cell numbers to meet the transplantation needs. We also showed that activation of the Wnt pathway made cells more readily tolerate ROS-caused mitochondria injury and cell apoptosis, thus making cells survive in autoimmune patients. The present study provides a theoretical basis for cell transplantation therapy of diabetes.

Differentiation of Mouse Pancreatic Stem Cells Into Insulin-Producing Cells by Recombinant Sendai Virus-Mediated Gene Transfer Technology.

Islet transplantation, including ß-cells, has proven to be effective for diabetes in many recent studies; however, this treatment strategy requires sufficient organ donors. One attractive approach for the generation of ß-cells is to utilize the expansion and differentiation of cells from pancreatic stem cells (PSCs), which are closely associated to the ß-cells lineage. In this study, we investigated whether important transcription factors (Pdx-1, Ngn3, NeuroD, and MafA) in islet cells could be efficiently transduced into mouse PSCs (mPSCs) using Sendai virus (SeV) vectors and found that the transduced cells were differentiated into insulin-producing pancreatic ß-cells. The mPSCs transduced with single transcription factors using SeV vectors could not express the insulin-2 mRNA. When combinations of two transcription factors were transduced using the SeV vectors, including combinations of Pdx-1 + NeuroD, Pdx-1 + MafA, and NeuroD + MafA, the expression of insulin-2 mRNA was low but could be detected. When combinations of three or more transcription factors were transduced using SeV vectors, the expression of insulin-2 mRNA could be detected. In particular, the transduction of the combination of PDX-1, NeuroD, and MafA produced the most effective for the expression of insulin-2 mRNA out of all of the different combinations examined. These data suggest that the transduction of transcription factors using SeV vectors facilitates mPSC differentiation into insulin-producing cells and showed the possibility of regenerating ß-cells by using transduced PSCs.