Estado actual del trasplante de islotes pancreáticos

[Cytoprotective effect of low-dose tacrolimus on islets of Langerhans in cultures subjected to stimulation by acute rejection cytokines]

INTRODUCTION

The improvement in pancreatic islet transplantation results is due to immunosuppression protocols that include, among others, low-dose tacrolimus. Both anti-inflammatory and anti-oxidant effects of tacrolimus could be useful in preventing primary rejection.

AIM

To evaluate in vitro islet low-dose tacrolimus response after pro-inflammatory stimulation.

MATERIAL AND METHODS

Isolated rat islets were cultured in RPMI medium in the presence of IL-1 (50 UI/mL) plus IF-gamma (1000 UI/mL) and tacrolimus (5 ng/mL). The 24 h production of lipoperoxide (LPO) and nitric oxide (NO) were measured as oxidative stress markers. Determination of apoptosis markers (nucleosome content and Bcl-2) was also performed.

RESULTS

Oxidative stress (LPO 10.1+/-1.16 pmol/islet x 24; NO 19.1+/-3.28 pmol/isletx24 h) and apoptosis (nucleosome 0.24+/-0.04 UI/islet; Bcl-2 0.69+/-0.212 UI/islet) markers showed a very significant increase after cytokine stimulation (p<0.01). Both effects improved by adding tacrolimus to the medium. Protective effect was complete when lipoperoxide (1.58 pmol/isletx24 h), nitric oxide (9.81 pmol/isletx24 h) and Bcl-2 (1.37+/-0.23 UI/islet) were determined.

CONCLUSION

In vitro cytoprotective effect of low-dose tacrolimus on isolated rat islets decreases both oxidative stress and apoptosis markers after stimulation of pro-inflammatory mediators.

Antiapoptotic effect of tacrolimus on cytokine-challenged human islets

Our goal was to investigate whether previously related antiapoptotic and anti-inflammatory effects of tacrolimus could be useful in protecting human islets cultured in the presence of several proinflammatory mediators. Human islets obtained from cadaveric donors after intraductal infusion with collagenase, mechanical digestion, and continuous Ficoll gradient purification were cultured in RPMI-1640 medium for 24 h. Escherichia coli lipopolysaccharide (10 microg/ml) or interleukin-1 (50 UI/ml) + gamma-IF (1000 UI/ml) and low-dose tacroliumus (5 ng/ml) were added. Homogenized samples (300 IE) from five different donors where assigned to four different experimental groups (control, treatment, cytokines, and cytokines + treatment). To evaluate islet damage and apoptotic response, nucleosome content, Bcl-2 protein levels, caspase-3, -8, and -9 levels, and insulin concentration were measured. Also, TNF-alpha and IL-6 levels where assessed as indicators of the inflammatory response. All proapoptotic markers, TNF-alpha, and IL-6 levels were augmented after both LPS and cytokine stimulation. Tacrolimus reduced significantly all of them and restored baseline values of nucleosome and caspase-9 in both experiments and Bcl-2 and caspase-3 when IL-1 + gamma-IF was added. Twenty-four-hour insulin concentration diminished when LPS or IL-1 + gamma-IF were present. Tacrolimus treatment restored insulin levels in both experiments. These results suggest that in vitro apoptotic events and media insulin concentration decrease after proinflammatory stimulation can be reverted using low-dose tacrolimus.

[Pancreatic islets transplantation in the treatment of diabetes mellitus: present and future]

Diabetes treatment with insulin does no prevent the development of secondary complications. For this reason, treatments other than conventional ones are needed, which could bring about an <> metabolic regulation. This can only be done by transplanting insulin producing tissue, such as vascularised pancreas transplantation, which is an already consolidated clinical procedure these days, or by islets transplantation, which is still a procedure in the clinical research phase. This has the same metabolic objectives as the vascularised transplant, but without the risks of major abdominal surgery, since the islets are implanted in the liver with minimal surgery or using interventionist radiology by means of a catheter. A clinical trial (Edmonton Protocol) was published in the year 2000, which improved the results after islet transplantation by obtaining normoglycaemia periods of more than one year in a consecutive patient series with type 1 diabetes and without using corticoids. This protocol has been endorsed in other centre in different trials. Although the initial results were good, the progress of these patients has shown that many islets transplantations do not manage to maintain insulin-independence indefinitely.

[Retrospective analysis of the use of the Spanish words severo and severidad in CIRUGIA ESPANOLA during 2007]

INTRODUCTION

The Spanish words severo (severe) and severidad (severity) are usually used as a synonyms of grave (serious) and gravedad (seriousness), although the Spanish Royal Academy of Language (Real Academia Española [RAE]) specifically recommends not to use them in this sense. A retrospective analysis to evaluate the use of the words severo and severidad in Cirugía Española during 2007 was performed.

MATERIAL AND METHOD

All the articles published in Cirugía Española during 2007 were reviewed. The articles in which severo and/or severidad were present were selected. For each article, the month of publication, the type of article, the geographic origin and the exact sentence containing these words were analyzed. Correctness and incorrectness of their use was studied according to the RAE normative.

RESULTS

A total of 33 articles were selected. Every month (except for January) had, at least, 2 articles. Thirty-one of the articles were from Spain whereas 2 were from Hispano-America. Eleven cases were original articles, 7 reviews, 6 case reports, 3 editorials, 3 special articles and 3 letters to the editor.

CONCLUSIONS

The Spanish words severo and severidad are inadequately used too often in scientific texts. It must be avoided using them as a synonym of grave, importante or serio, incorrect translations of the English word severe.

Comprehensive analysis of human pancreatic islets using flow and laser scanning cytometry

Assessing islet cellular composition and beta cell viability using Flow Cytometry (FC) and Laser Scanning Cytometry (LSC) may aid in determining the transplant quality of islets. Human islets (2500 IEQ, n = 44, purity >or=80%) dissociated into a single cell suspension were stained with ductal marker CA19, with Newport Green (NG) and FluoZin3 (FL3) for beta-cell identification, with TMRE to assess mitochondrial membrane potential, with DAPI to identify live vs. dead cells, and with Annexin-V/DAPI to differentiate apoptotic and necrotic cells. For LSC, cell preparations (n = 9) were stained for insulin (beta-cells), glucagon (alpha-cells), somatostatin (delta cells), and pancreatic polypeptide (ppp cells). Fluorescence microscopy (EtBr/FDA) and insulin response were also measured. DAPI- staining was 73.78% +/- 1.37, while EtBr/FDA was 96% +/- 0.48. 52.5% +/- 3.73 of all cells were NG+, of which 58.08% +/- 2.61 were NG+/TMRE+. Annexin-V/DAPI staining (n = 26) showed 13.8% +/- 0.89 apoptotic, 27.2% +/- 2.0 necrotic, and 51.9% +/- 2.22 live cells. 26.0% +/- 5.19 of cells were CA19 positive (n = 17), of which 45.5% +/- 4.37 were also TMRE+, and 5.2% +/- 1.2 of the TMRE+ were also NG+/CA19+. NG and FL3 showed similar staining (n = 8). Comparison of short-term (<or=2 days) versus long-term (>or=3 days) culture showed similar TMRE+/NG+ averages, albeit lower percentages of live (36.4% vs 51.9%), and higher percentages of apoptotic (19.2% vs 13.8%) and necrotic cells (37.4% vs 27.2%) for long-term, as determined by Annexin-V staining. LSC resulted in 54.17% +/- 4.62 beta-cells, 33.33% +/- 4.16 alpha-cells, 8.75% +/- 2.5 delta-cells, and 3.75% +/- 0.79 ppp cells. There is no significant difference between insulin positive cells and NG positive cells (P <or= .55). FC and LSC provide valuable information about islet quality, which could potentially be used for evaluating islets prior to transplantation.