Insulin - producing cells derived from stem cells: recent progress and future directions

Type 1 diabetes is characterized by the selective destruction of pancreatic beta-cells caused by an autoimmune attack. Type 2 diabetes is a more complex pathology which, in addition to beta-cell loss caused by apoptotic programs, includes beta-cell dedifferentiation and peripheric insulin resistance. beta-Cells are responsible for insulin production, storage and secretion in accordance to the demanding concentrations of glucose and fatty acids. The absence of insulin results in death and therefore diabetic patients require daily injections of the hormone for survival. However, they cannot avoid the appearance of secondary complications affecting the peripheral nerves as well as the eyes, kidneys and cardiovascular system. These afflictions are caused by the fact that external insulin injection does not mimic the tight control that pancreatic-derived insulin secretion exerts on the body's glycemia. Restoration of damaged beta-cells by transplantation from exogenous sources or by endocrine pancreas regeneration would be ideal therapeutic options. In this context, stem cells of both embryonic and adult origin (including beta-cell/islet progenitors) offer some interesting alternatives, taking into account the recent data indicating that these cells could be the building blocks from which insulin secreting cells could be generated in vitro under appropriate culture conditions. Although in many cases insulin-producing cells derived from stem cells have been shown to reverse experimentally induced diabetes in animal models, several concerns need to be solved before finding a definite medical application. These refer mainly to the obtainment of a cell population as similar as possible to pancreatic beta-cells, and to the problems related with the immune compatibility and tumor formation. This review will summarize the different approaches that have been used to obtain insulin-producing cells from embryonic and adult stem cells, and the main problems that hamper the clinical applications of this technology.

Transient transcriptional response to low-dose ionizing radiation in humans undergoing IMRT

20018

Background: As intensity modulated radiation therapy techniques are increasingly utilized to treat cancer, the area of normal tissue exposed to ionizing radiation is increasing. The biologic risks associated with this normal tissue low dose exposure (LDIR) are fundamentally unknown and of concern to cancer survivors following therapy. Current modeling for health regulations presupposes a linear, no-threshold model of radiation effects, which estimates the effect and risk at low dose by extrapolation from measured effects at high doses. Cell culture models of ionizing radiation (RT) exposure show variable effects, not consistent with a linear dose-response relationship. We therefore undertook the first study to our knowledge of transcriptional effects of LDIR over time in vivo in solid tissue in humans. Methods: Tissue was collected at pre-RT, 3, 8, and 24 hours post-IR at sites receiving 10cGy. Transcriptional response at 3 and 8 hours were compared to the 0 and 24 hour time points. If transcripts are up regulated or down regulated at 3 and 8 hours compared with 0 and 24 hours, we have detected a transient response. The method of Rocke (2005), which was designed to detect differentially expressed gene groups using the responses of multiple probe sets corresponding to gene groups, was used to allow us to test whether there is differential expression for each patient separately, as well as for all the patients together. Results: Significant (p < 0.05) transient up regulation was shown in zinc finger proteins, keratins, BMP receptors, BAG, cyclins and BCL 6. Down regulation was detected in TNF, protein disulfide isomerase, interleukins, heat shock proteins, and S100. Nine gene groups did not show significant change; however, the number of significant gene groups (11) far exceeds the number expected by chance (2). In most cases in which a gene group was shown to be transiently altered, the tests of individual patients showed that most or all of the individuals also had differential expression of the same type. Conclusions: We have shown that it is possible to detect transient responses to LDIR in vivo in humans, and have identified eleven gene groups that demonstrate transient changes, as measured by a statistically principled analysis method.

No significant financial relationships to disclose.

From stem cells to insulin-producing cells: towards a bioartificial endocrine pancreas

The total absence or low production of insulin by beta-cells avoids a proper control of glycemia forcing diabetic people to daily insulin injection for survival. Islet transplantation represents a hallmark in the cure of diabetes and has been successfully applied to more than 400 patients, resulting in insulin independency for periods longer than 4 years. However, transplantation trials for diabetes have to face the scarcity of islets from cadaveric donors. Therefore, the finding of renewable sources of cells could circumvent this problem. In this respect, embryonic or adult stem cells are representing an interesting alternative. Stem cells display robust proliferation and the plasticity to differentiate to other cell types, including insulin-containing cells. The current therapeutical use in the future of bioengineered insulin-secreting cells derived from stem cells needs at present to fulfill several criteria. These criteria concern to the type of stem cell to be used as starting biomaterial (embryonic or adult), the in vitro differentiation protocol applied, the functional phenotype reached for the final cell product and the transplantation associated problems (likely immune rejection and tumor formation). This review will try to focus on these different aspects in order to emphasize in the key points to consider for designing unified strategies for diabetes cell therapy.

[Autoimmune thyroid disease: a case report]

Autoimmune thyroid disease is the most common cause of subclinical thyroid dysfunction (hypo and hyperthyroidism) in the western countries. Autoimmune thyroid diseases with clinical relevance (Graves' disease and autoimmune hypothyroidism) are common and can present with a large clinical and laboratorial spectrum. Hypo and hyperthyroidism can exist in the same patient, on different times. Progression from Graves hyperthyroidism to chronic autoimmune thyroiditis and hypothyroidism is now well-recognized and the inverse might also occur, although being rare. We describe a case report of Graves' disease in a patient with a chronic autoimmune hypothyroidism of long course (diagnosed 21 years ago).

Primary hyperoxaluria type 1 in the Canary Islands: a conformational disease due to I244T mutation in the P11L-containing alanine:glyoxylate aminotransferase

Primary hyperoxaluria type 1 (PH1) is an inborn error of metabolism resulting from a deficiency of alanine:glyoxylate aminotransferase (AGXT; EC 2.6.1.44). Most of the PH1 alleles detected in the Canary Islands carry the Ile-244 --> Thr (I244T) mutation in the AGXT gene, with 14 of 16 patients homozygous for this mutation. Four polymorphisms within AGXT and regional microsatellites also were shared in their haplotypes (AGXT*LTM), consistent with a founder effect. The consequences of these amino acid changes were investigated. Although I244T alone did not affect AGXT activity or subcellular localization, when present in the same protein molecule as Leu-11 --> Pro (L11P), it resulted in loss of enzymatic activity in soluble cell extracts. Like its normal counterpart, the AGXT*LTM protein was present in the peroxisomes but it was insoluble in detergent-free buffers. The polymorphism L11P behaved as an intragenic modifier of the I244T mutation, with the resulting protein undergoing stable interaction with molecular chaperones and aggregation. This aggregation was temperature-sensitive. AGXT*LTM expressed in Escherichia coli, as a GST-fusion protein, and in insect cells could be purified and retained enzymatic activity. Among various chemical chaperones tested in cell culture, betaine substantially improved the solubility of the mutant protein and the enzymatic activity in cell lysates. In summary, I244T, the second most common mutation responsible for PH1, is a protein conformational disease that may benefit from new therapies with pharmacological chaperones or small molecules to minimize protein aggregation.

Comparison of cervical smears secured with different instruments

BACKGROUND

In this presentation we have compared the results from cytologic samples obtained with the cervical brush and Ayre's wooden spatula, against samples obtained with Acellon Combi.

METHODS

One thousand cervical smears were collected. This was a cross-sectional study, where it was decided randomly to use cervical brush for sampling of the endocervix and Ayre's wooden spatula for exocervix or Acellon Combi for both.

RESULTS

The combination of the cervical brush and the wooden spatula yielded an acceptable quantity of columnar cells in 71.6% of the cases, during both endocervical and exocervical sampling, while the Acellon Combi yielded an acceptable quantity in 61.7% of the cases (p<0.01). The combination of brush/spatula yielded an acceptable quantity of squamous cells from samples of endocervix and exocervix in 87.5% cases, while with the Acellon device amounted to 77.4% (p<0.001). Highly significant differences in the state of cellular preservation of samples from endocervix obtained with cervical brush technique were found upon comparison to Acellon group.

CONCLUSIONS

Henceforth, we believe that the use of the cervical brush and the Ayre wooden spatula increases the quantity and preservation of the cells retrieved during cervical smears compared to Acellon Combi.

Mild hypothermia mitigates post-ischemic neuronal death following focal cerebral ischemia in rat brain: immunohistochemical study of Fas, caspase-3 and TUNEL

Mild hypothermia is considered to have a protective effect during ischemic neuronal cell death. The present study provides experimental evidence for this beneficial role of mild hypothermia using reversible middle cerebral artery occlusion (MCAo) in a Sprague-Dawley (SD) rat model. MCAo was induced in rats for 1 h followed by reperfusion at different periods. Hematoxylin-eosin (HE) staining in normothermic (NT) 37 degrees C and hypothermic (HT) 33 degrees C groups of rats confirmed cerebral infarcts. The mean per cent infarct area was significantly reduced in the HT group of rats. Immunohistochemical analysis was done using anti-Fas and caspase-3 antibodies. The immunohistochemical expression of Fas and caspase-3 was demonstrable as early as 5 h after reperfusion, but the expression pattern maximized at 24 h after reperfusion. The expression of Fas and caspase-3 proteins showed a clear decrease in the HT group over the NT group. In situ detection of DNA fragmentation was done using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling method (TUNEL). TUNEL-positive cells were first observed at 5h after reperfusion and progressively increased by 24h. A higher number of TUNEL-positive cells was found in the NT group, but they were significantly decreased in the HT group. Further, DNA fragmentation was confirmed by size fractionation in agarose gel. These findings demonstrate a positive relation between the expression of Fas, caspase-3 and TUNEL-positive cells.

[A multifocal granular-cell tumor of the upper airways]

Granular cell tumor now is considered to be a neoplasm with the same origin as schwannomas and it should be considered in the differential diagnosis of small tumors of the upper airway. These tumors usually appear as isolated lesions. We report the case of a male patient with three simultaneous granular cell tumors located in the anterior pillar of the tonsil, vocal cord and arytenoid. Although seldom malignant, these tumors can be misdiagnosed as squamous-cell carcinomas because they induce pseudoepitheliomatous hyperplasia of the overlying epithelium. They should be excised with broad margins because they tend to infiltrate.