Comparative Evaluation of RNAlater Solution and Snap Frozen Methods for Gene Expression Studies in Different Tissues

Chronic changes developing in the hydronephrotic and contralateral kidneys during unilateral ureteral obstruction in rats

BACKGROUND

Animal models of chronic kidney disease are important experimental tools used to validate new mechanisms and potential innovations, as well as to investigate therapeutic interventions before clinical trials in humans. This study aimed to determine the chronic changes occurring in the obstructed kidneys (OK) and the contralateral (CL) kidneys in unilateral ureteral obstruction (UUO) in rats.

METHODS AND RESULTS

In the study, three groups (n:6) were formed. It was observed that dilated tubules decreased at 28 days compared to 14 days, while mononuclear cell infiltration and fibrosis increased. In the CL kidneys, glutathione (GSH) was lower compared to the control group (CG) at 14 days; at 28 days, malondialdehyde (MDA) was elevated, and GSH and catalase (CAT) levels were reduced. Nuclear factor erythroid 2-related factor 2 (NRF-2) protein expression was lower in the OK compared to the CL kidneys at both 14 and 28 days. NRF-2 gene expression was lower in the OK only at 28 days compared to the CG. However, in the CL kidneys, NRF-2 gene expression was higher at both 14 and 28 days compared to the CG. Cyclooxygenase-2 (COX-2) protein levels showed a significant increase in both the OK and CL kidneys at 14 days. COX-2 gene expression increased in the OK at 14 days compared to the CG. BAX protein levels were lower in the OK at 28 days compared to both the CG and CL kidneys. BCL-2 protein levels were lower in the OK compared to the CL kidneys at both 14 and 28 days.

CONCLUSION

This study has identified changes in both the OK and CL kidneys, providing significant data for potential therapeutic, supportive, or protective research aimed at treating these kidneys.

"Optimal timing for RNA isolation: Recommendations for placenta sample collection under clinical conditions"

In placenta research, tissue quality is essential for following laboratory investigations. In clinical settings with deliveries as an unpredictable factor, delayed sampling or incorrect storage until sampling is a common problem. Therefore, we set out to define time points for different storage conditions where good tissue quality is still achievable. RNA related parameters like 260/280-ratio, RNA integrity number (RIN) and gene expression were analyzed in 172 samples over a 24-h interval. We suggest a cut-off-point of 3-h after delivery of the placenta to ensure good tissue and RNA quality, especially when selecting genes with complex or low mRNA expression levels.

Optimization of RNA storage in a biobank, as well as methods for manual and automated isolation of RNA from whole blood and leukocyte fraction

Aim. To optimize the technique for the isolation and storage of ribonucleic acid (RNA) from whole blood and leukocyte fraction.

Materials and methods. Comparison of isolation quality was carried out for RNA samples obtained from 228 leukocyte samples and 198 whole blood samples. Isolation was performed from fresh and frozen samples using ExtractRNA™ reagent and a MagNA Pure Compact automated system. Various methods of removing erythrocytes (centrifugation and treatment with hemolytic agents from two manufacturers) were tested, as well as freezing with and without preservatives for subsequent RNA isolation.

Results. Twenty-one combinations of conditions were tested. The highest quality RNA was isolated by manual extraction using the ExtractRNA™ reagent from a fresh leukocyte fraction, purified by the Amplisens hemolytic agent (successful extraction — 94%, median RIN=8,4); frozen in IntactRNA™, purified by leukocyte fraction centrifugation (successful extraction — 100%, median RIN=8); frozen in ExtractRNA™, purified by leukocyte fraction centrifugation (successful extraction — 100%, median RIN=9,3).

Conclusion. RNA can be isolated from frozen blood fractions, which is not inferior in quality to that isolated from fresh samples. Thus, it is not necessary to isolate RNA immediately after the receipt of biological material.