Effects of cryopreservation and coculture with pancreatic ductal epithelial cells on insulin secretion from human pancreatic islets

Long-term storage methods, such as cryopreservation and long-term in vitro culture, hinder the therapeutical application of pancreatic islet transplantation, because they decrease islet viability. Pancreatic ductal epithelial cells (DEC) are putative stem cells for islets, which may secrete specific factors supporting islet growth and function. Hence, we studied the effect of coculture with DEC on the viability of fresh and cryopreserved human pancreatic islets. Islets and DEC were isolated from the pancreas of an organ donor, and part of them were cryopreserved. Fresh and cryopreserved-thawed islets were cultured alone or in the presence of DEC for 14 days at 33degreesC or 37degreesC. At day I and day 14 of culture, insulin secretion was stimulated by two sequential 45-min exposures to low and high glucose concentrations (3.3 and 16.7 mmol/l, respectively). Insulin concentrations were measured by radioimmunoassay, and the ratio between the insulin responses to high and low glucose was calculated (insulin stimulation index, ISI). After 14 days of culture, some fresh islets were processed for scanning, electron microscopy (SEM). At day 14, ISI was markedly reduced in both fresh and cryopreserved islets with respect to I day cultures. Cryopreservation reduced ISI at day 1 and day 14, but in the latter case only when cultures were maintained at 37degreesC. Coculture with DEC did not affect ISI of fresh islets at day 1, and enhanced it at day 14, but only at a culture temperature of 33degreesC. Conversely, coculture raised ISI of cryopreserved islets at both day I and day 14, independently of the culture temperature. SEM showed that at day 14 of culture, the morphology of fresh islets displayed the best preservation when cocultured with DEC at 33degreesC. Our findings confirm that both lone-term culture and cryopreservation decrease viability of human pancreatic islets. Moreover, they indicate that coculture of islets with DEC at 33degreesC represents a valuable tool to improve the survival and functional activity of islets, especially in the case of cryopreserved material

Neurotoxicity of Olindias sambaquiensis and Chiropsalmus quadrumanus extracts in sympathetic nervous system

Cnidarians are equipped with nematocysts, which are specialized organelles used to inoculate venom during prey capturing and defense. Their venoms are rich in toxins and a potential source of bioactive compounds, however, poorly explored so far. In this work, the activity of the methanolic extracts from the hydromedusa Olindias sambaquiensis and the cubozoan jellyfish Chiropsalmus quadrumanus were studied in sympathetic neurotransmission. For that, bisected rat vas deferens - a classic model of sympathetic neurotransmission - were incubated with the extracts for further myographic and histopathological analysis. The O. sambaquiensis extract, at 0.1 μg/mL, facilitated the neurogenic contractions of the noradrenergic-rich epididymal portion, while reducing the noradrenaline (NA) potency, which suggests an interaction with postsynaptic α1-adrenoceptors. On the other hand, a higher concentration (1 μg/mL) leads to time- and frequency-dependent blockade of nerve-evoked contractions without significantly changing the response to exogenous NA. In turn, the C. quadrumanus extract at 0.1 μg/mL induced blockade of nerve-evoked noradrenergic contractions while reducing the potency to exogenous NA. Both extracts did not affect the purinergic neurotransmission or induce muscle damages. Our results demonstrate that O. sambaquiensis and C. quadrumanus extracts significantly interfere with the noradrenergic neurotransmission without altering purinergic response or smooth muscle structure on rat vas deferens. Such results bring to light the pharmacological potential of O. sambaquiensis and C. quadrumanus molecules for therapeutics focusing on noradrenergic neurotransmission

Molecular features of 3D cultured cells.

Molecular features of 3D cultured cells.</p