Role of stem cells in kidney repair

Study on therapeutic action of bone marrow derived mesenchymal stem cell combined with vitamin E against acute kidney injury in rats

AIMS

The study aims to investigate the effect to treat acute kidney injury (AKI) with bone marrow derived mesenchymal stem cells (BMSCs) combined with vitamin E and to develop a new treatment mode for AKI preclinical study.

MAIN METHODS

BMSCs were separated from rat bone marrow. Gentamicin was used as a damage factor in the culture of renal tubular epithelial cells (RTECs) in vitro. After co-cultured with BMSCs and vitamin E, cell proliferation of each group was detected with CCK-8. In vivo, BMSCs (3.3×10(6)cells/kg) combined with vitamin E (80mg/kg) were administered in AKI rats induced by gentamicin intravenously. The pathological changes, biochemical parameters and apoptosis genes after treatment were investigated furthermore.

KEY FINDINGS

In co-cultured system, proliferating ability of RTECs was improved by BMSCs or vitamin E, especially for the combined group (P<0.05). The treated rats in combined group presented the lowest serum creatinine and the highest urea nitrogen compared to non-treated rats. The improvement in renal pathological changes was followed by less necrosis, degeneration and expansion of renal tubule. Under transmission electron microscope, unclear cell structure and reduction of endoplasmic reticulum in the cytoplasm of RTECs were ameliorated with the treatment. Most apoptosis genes were up-regulated in model group while down-regulated with the therapy. Further analysis showed that the two treatments may act independently with each other.

SIGNIFICANCE

Our data demonstrated that both BMSC and vitamin E hold therapeutic action to AKI induced by gentamicin. Especially, the combined treatment is better than BMSC or vitamin E alone.

Ischemia/reperfusion-induced renal failure in rats as a model for evaluating cell therapies

Chronic renal failure is a devastating disease that leads to a multitude of complications. Cell therapy has emerged as a potential treatment modality for renal failure. However, efficacy testing on systemic renal function has been challenging due to the limited availability of reliable models that are fully characterized. In this study, we investigated the possibility of using renal ischemia/reperfusion (I/R) injury as a viable model for testing cell therapies. We examined functional and pathological changes in rat kidneys that were exposed to different ischemia times. Male Lewis rats were divided into five groups. Renal failure was induced by clamping both renal pedicles for combinations of 60, 75, and 90 min, followed by reperfusion. Age-matched healthy rats served as controls. Blood was collected at regular intervals for serum chemistry, and kidneys were harvested at the same intervals for histomorphological assessment. Serum creatinine levels of the animals with I/R injury increased significantly after 3 days and returned to normal levels at 4 weeks. Histologically, kidney tissue showed progressive glomerular and tubular deterioration with varying degrees of fibrosis. Animals exposed to 75- and 90-min ischemia combination times consistently generated more severe injury than the 60-min ischemia period. However, these groups resulted in a high mortality rate. A model in which one kidney is exposed to a shorter ischemia time (60 or 90 min) resulted in sustained renal damage with a lower mortality rate. This study shows that kidneys exposed to I/R result in renal tissue damage as well as decreased renal function. This model can be used to study both the short-term and longer-term effects of kidney disease by varying the length of the ischemic time. In particular, the use of longer ischemic times (75 and 90 min) could be used to study new therapies for acute renal disease, whereas shorter ischemic times (60 min) could be used to study therapies for chronic renal insufficiency.

Ochratoxin A at nanomolar concentration perturbs the homeostasis of neural stem cells in highly differentiated but not in immature three-dimensional brain cell cultures

Ochratoxin A (OTA), a fungal contaminant of basic food commodities, is known to be highly cytotoxic, but the pathways underlying adverse effects at subcytotoxic concentrations remain to be elucidated. Recent reports indicate that OTA affects cell cycle regulation. Therefore, 3D brain cell cultures were used to study OTA effects on mitotically active neural stem/progenitor cells, comparing highly differentiated cultures with their immature counterparts. Changes in the rate of DNA synthesis were related to early changes in the mRNA expression of neural stem/progenitor cell markers. OTA at 10nM, a concentration below the cytotoxic level, was ineffective in immature cultures, whereas in mature cultures it significantly decreased the rate of DNA synthesis together with the mRNA expression of key transcriptional regulators such as Sox2, Mash1, Hes5, and Gli1; the cell cycle activator cyclin D2; the phenotypic markers nestin, doublecortin, and PDGFRα. These effects were largely prevented by Sonic hedgehog (Shh) peptide (500ngml(-1)) administration, indicating that OTA impaired the Shh pathway and the Sox2 regulatory transcription factor critical for stem cell self-renewal. Similar adverse effects of OTA in vivo might perturb the regulation of stem cell proliferation in the adult brain and in other organs exhibiting homeostatic and/or regenerative cell proliferation.