Uremic Toxins Affect the Imbalance of Redox State and Overexpression of Prolyl Hydroxylase 2 in Human Adipose Tissue-Derived Mesenchymal Stem Cells Involved in Wound Healing

Abstract

Chronic kidney disease (CKD) results in a delay in wound healing because of its complications such as uremia, anemia, and fluid overload. Mesenchymal stem cells (MSCs) are considered to be a candidate for wound healing because of the ability to recruit many types of cells. However, it is still unclear whether the CKD-adipose tissue-derived MSCs (CKD-AT-MSCs) have the same function in wound healing as healthy donor-derived normal AT-MSCs (nAT-MSCs). In this study, we found that uremic toxins induced elevated reactive oxygen species (ROS) expression in nAT-MSCs, resulting in the reduced expression of hypoxia-inducible factor-1α (HIF-1α) under hypoxic conditions. Consistent with the uremic-treated AT-MSCs, there was a definite imbalance of redox state and high expression of ROS in CKD-AT-MSCs isolated from early-stage CKD patients. In addition, a transplantation study clearly revealed that nAT-MSCs promoted the recruitment of inflammatory cells and recovery from ischemia in the mouse flap model, whereas CKD-AT-MSCs had defective functions and the wound healing process was delayed. Of note, the expression of prolyl hydroxylase domain 2 (PHD2) is selectively increased in CKD-AT-MSCs and its inhibition can restore the expression of HIF-1α and the wound healing function of CKD-AT-MSCs. These results indicate that more studies about the functions of MSCs from CKD patients are required before they can be applied in the clinical setting.

Uremic Toxins Activates Na/K-ATPase Oxidant Amplification Loop Causing Phenotypic Changes in Adipocytes in In Vitro Models

“…Obesity, which is closely linked to CKD, is associated with dysfunctional white adipose tissue and imbalances in adipokine secretion, leading to a chronic inflammatory state and increased oxidative stress [ 22 ]. Fat accumulation is positively correlated with systemic oxidative stress in both humans and mice [ 13 ], and mouse models of obesity have increased oxidative stress in plasma due to increased ROS and cytokines production from accumulated fat [ 13 , 23 ]. Obesity is also associated with reduced antioxidant defenses in adipocytes, which could reduce their capacity to respond to oxidative stress [ 13 ].…”

Diabetic Kidney Disease Alters the Transcriptome and Function of Human Adipose-Derived Mesenchymal Stromal Cells but Maintains Immunomodulatory and Paracrine Activities Important for Renal Repair

“…Indeed, DM impairs stem cell mobilization and therapeutic effect in experimental DKD (29,31), alters the MSC secretome, and reduces neoangiogenesis in DM ischemic limb disease (29,32,33). We and others also identified altered paracrine MSC function in non-DM conditions, suggesting that disease hinders endogenous repair activities (21,34,35). The functionality of culture-expanded MSCs in human DKD remains to be established.…”

“…The functionality of culture-expanded MSCs in human DKD remains to be established. In primarily participants with non-DM CKD, MSCs exhibited preserved cytokine and growth factor gene expression and therapeutic effect (34,36,37), but subsequent studies in human ESKD and in vitro uremic toxin exposure revealed functional impairment (34,35,38).…”

Rejuvenation of mesenchymal stem cells by extracellular vesicles inhibits the elevation of reactive oxygen species

“…In order to measure the intracellular ROS level, 2′,7′-dichlorodihydrofluorescein diacetate (H2-DCFDA; Invitrogen) was used as the probe according to a previously described method 46 . In brief, after reaching 80% confluency, the cells were washed with PBS and incubated with PBS containing 10 μM DCFDA at 37 °C for 30 min.…”

“…AT-MSCs were collected, and nuclear protein was extracted according to the manufacturer’s protocol (Life Technologies) and previously described method 46 . The extracted protein concentration was measured by Bradford method (Bio-rad, CA, US).…”