Evaluation of Pancreatic ß-cell Differentiation Efficiency of Human iPSC Lines for Clinical Use.

BACKGROUND: Transplantation of pancreatic ß-cells generated from human induced pluripotent stem cells (hiPSCs) has great potential as a root treatment for type 1 diabetes. However, their current level of efficiency to differentiate into ß-cells is still not at par for clinical use. Previous research has shown that differentiation efficiency varies among human embryonic stem cells and mouse-induced pluripotent stem cell lines. Therefore, selecting a suitable cell line for efficient induction into desired tissues and organs is crucial. METHOD: In this study, we have evaluated the efficiency of 15 hiPSC lines available for clinical use to differentiate into pancreatic ß-cells. RESULTS: Our investigation has revealed induction efficiency to differ among the hiPSC lines, even when derived from the same donor. Among the hiPSC lines tested, the 16A01 cell line exhibited the highest insulin expression and low glucagon expression, suggesting that this cell line is suitable for differentiation into ß-cells. CONCLUSION: Our study has demonstrated the importance of selecting a suitable hiPSC line for effective differentiation into ß-cells.

A simple method of hiPSCs differentiation into insulin-producing cells is improved with vitamin C and RepSox.

Human induced pluripotent stem cells (hiPSCs) are considered a promising source of pancreatic ß-cells for the treatment of diabetes. However, this approach is limited by issues such as low efficiency and high cost. Here, we have developed a new protocol to induce insulin-producing cells. To reduce costs, we decreased the number of reagents and replaced protein reagents with chemical compounds. In this method, we increased induction efficiency with ascorbic acid (vitamin C) and an ALK5 inhibitor, RepSox. In 2D culture, the majority of cells were immature ß-cells with low glucose-stimulated insulin secretion. Transferring to 3D culture immediately after endocrine progenitor cell differentiation, however, improved glucose-stimulated insulin secretion. This simplified method will contribute to realizing transplantation therapy of ß-cells using iPSCs.

Quantification of Chitinase mRNA Levels in Human and Mouse Tissues by Real-Time PCR: Species-Specific Expression of Acidic Mammalian Chitinase in Stomach Tissues.

Chitinase hydrolyzes chitin, which is an N-acetyl-D-glucosamine polymer that is present in a wide range of organisms, including insects, parasites and fungi. Although mammals do not contain any endogenous chitin, humans and mice express two active chitinases, chitotriosidase (Chit1) and acidic mammalian chitinase (AMCase). Because the level of expression of these chitinases is increased in many inflammatory conditions, including Gaucher disease and mouse models of asthma, both chitinases may play important roles in the pathophysiologies of these and other diseases. We recently established a quantitative PCR system using a single standard DNA and showed that AMCase mRNA is synthesized at extraordinarily high levels in mouse stomach tissues. In this study, we applied this methodology to the quantification of chitinase mRNAs in human tissues and found that both chitinase mRNAs were widely expressed in normal human tissues. Chit1 mRNA was highly expressed in the human lung, whereas AMCase mRNA was not overexpressed in normal human stomach tissues. The levels of these mRNAs in human tissues were significantly lower than the levels of housekeeping genes. Because the AMCase expression levels were quite different between the human and mouse stomach tissues, we developed a quantitative PCR system to compare the mRNA levels between human and mouse tissues using a human-mouse hybrid standard DNA. Our analysis showed that Chit1 mRNA is expressed at similar levels in normal human and mouse lung. In contrast, the AMCase expression level in human stomach was significantly lower than that expression level observed in mouse stomach. These mRNA differences between human and mouse stomach tissues were reflecting differences in the chitinolytic activities and levels of protein expression. Thus, the expression level of the AMCase in the stomach is species-specific.

The effectiveness of "Protex" for disinfection of the ultrasound probe.

The aim of this study was to evaluate the effectiveness of "Protex" (Parker; Fairfield, NJ, USA) for disinfection of ultrasound probes. We examined bacterial contamination on ultrasound probes that were wiped with a plain paper towel, with a plain and an ethanol-soaked paper towel, or with a plain and Protex-soaked paper towel. The plain paper towel was used to remove the gel, and was contaminated by large numbers of bacteria, but the use of ethanol-soaked paper towels and that of paper towels soaked in Protex™ broad-spectrum disinfectant (Parker: Fairfield, NJ, USA) reduced those numbers markedly.

Chitinase mRNA levels by quantitative PCR using the single standard DNA: acidic mammalian chitinase is a major transcript in the mouse stomach.

Chitinases hydrolyze the ß-1-4 glycosidic bonds of chitin, a major structural component of fungi, crustaceans and insects. Although mammals do not produce chitin or its synthase, they express two active chitinases, chitotriosidase (Chit1) and acidic mammalian chitinase (AMCase). These mammalian chitinases have attracted considerable attention due to their increased expression in individuals with a number of pathological conditions, including Gaucher disease, Alzheimer's disease and asthma. However, the contribution of these enzymes to the pathophysiology of these diseases remains to be determined. The quantification of the Chit1 and AMCase mRNA levels and the comparison of those levels with the levels of well-known reference genes can generate useful and biomedically relevant information. In the beginning, we established a quantitative real-time PCR system that uses standard DNA produced by ligating the cDNA fragments of the target genes. This system enabled us to quantify and compare the expression levels of the chitinases and the reference genes on the same scale. We found that AMCase mRNA is synthesized at extraordinarily high levels in the mouse stomach. The level of this mRNA in the mouse stomach was 7- to 10-fold higher than the levels of the housekeeping genes and was comparable to that the level of the mRNA for pepsinogen C (progastricsin), a major component of the gastric mucosa. Thus, AMCase mRNA is a major transcript in mouse stomach, suggesting that AMCase functions as a digestive enzyme that breaks down polymeric chitin and as part of the host defense against chitin-containing pathogens in the gastric contents. Our methodology is applicable to the quantification of mRNAs for multiple genes across multiple specimens using the same scale.

Influence of the timing of switching a protein-free to a protein-containing diet on the wound healing process in a rat all-layer skin defect.

We prepared full thickness skin defects in rats fed on a protein-free diet as a hypoproteinaemia model, then switched the animals to a diet containing a normal protein level 1, 6 or 12 days after wounding (inflammatory, granulation and rearrangement phases of the wound healing process) to examine whether improvement in the low-protein state promotes subsequent wound healing. The interval until wound healing in rats fed on a normal protein diet was significantly shorter, whereas that in rats continuously fed on a protein-free diet was significantly longer than those of other groups. Early correction tended to accelerate wound healing. Although wound contraction in groups receiving a protein-corrected or protein-free diet remained similar until 15 days after wounding, thereafter the duration of the rearrangement phase was significantly longer in the protein-free group than in the other groups. The collagen level per unit of granulation tissue area during wound healing was significantly lower in the protein-free group than in the other groups. These findings indicate that protein correction at any time after wounding accelerates wound healing, although early correction is more effective, and reduces the duration of the rearrangement phase more than those of the inflammatory and granulation phases because of the deposit of collagen.