Stem Cells from a Female Rat Model of Type 2 Diabetes/Obesity and Stress Urinary Incontinence Are Damaged by In Vitro Exposure to its Dyslipidemic Serum, Predicting Inadequate Repair Capacity In Vivo

Abstract

Female stress urinary incontinence (FSUI) is prevalent in women with type 2 diabetes/obesity (T2D/O), and treatment is not optimal. Autograph stem cell therapy surprisingly has poor efficacy. In the male rat model of T2D/O, it was demonstrated that epigenetic changes, triggered by long-term exposure to the dyslipidemic milieu, led to abnormal global transcriptional signatures (GTS) of genes and microRNAs (miR), and impaired the repair capacity of muscle-derived stem cells (MDSC). This was mimicked in vitro by treatment of MDSC with dyslipidemic serum or lipid factors. The current study aimed to predict whether these changes also occur in stem cells from female 12 weeks old T2D/O rats, a model of FSUI. MDSCs from T2D/O (ZF4-SC) and normal female rats (ZL4-SC) were treated in vitro with either dyslipidemic serum (ZFS) from late T2D/O 24 weeks old female Zucker fatty (ZF) rats, or normal serum (ZLS) from 24 weeks old female Zucker lean (ZL) rats, for 4 days and subjected to assays for fat deposition, apoptosis, scratch closing, myostatin, interleukin-6, and miR-GTS. The dyslipidemic ZFS affected both female stem cells more severely than in the male MDSC, with some gender-specific differences in miR-GTS. The changes in miR-GTS and myostatin/interleukin-6 balance may predict in vivo noxious effects of the T2D/O milieu that might impair autograft stem cell (SC) therapy for FSUI, but this requires future studies.

Evaluation of the In Vitro Damage Caused by Lipid Factors on Stem Cells from a Female Rat Model of Type 2 Diabetes/Obesity and Stress Urinary Incontinence

“…Figure 1 shows that in ZL4-SC, cholesterol doubled the low apoptotic index found in the control without addition, measured by quantitative image analysis of the TUNEL reaction, resembling what was reported for the dyslipidemic serum added to 5% [ 8 ]. Na palmitate was much more damaging, nearly quadruplicating apoptosis.…”

“…As previously reported [ 8 ], 12 weeks old female Zucker Fatty (ZF) rats (ZUC-Lepr fa/fa 186), and their Zucker Lean (ZL) controls (ZUC-Lepr fa 185) of the same strain used for the study on male rats [ 5 , 6 , 7 ] were used here for isolating the female stem cells. The ZF rats are a model of metabolic syndrome, in the male evolving into frank diabetes and morbid obesity, whereas in the female leading to a more marginal hyperglycemia and moderate obesity, both identified as T2D/O.…”

“…We wished to determine whether the effects previously found with both types of female stem cells incubated for 4–5 days with 5% highly dyslipidemic serum from ZF rats aged to over 23 months of age [ 8 ], were reproduced with individual serum lipids. The incubations in the current work were performed with water-soluble preparations of cholesterol at 50 mg/dL, or Na palmitate (as representative free fatty acid) at 0.5 mM, instead of dyslipidemic serum addition, for all the tests.…”

“…Finally, another study from our group investigated [ 8 ] whether this damage induced in vitro on male stem cells may similarly occur in female MDSC involved in endogenous tissue repair, and consequently, the gender dependency of MDSC susceptibility to damage. If the damage was gender independent, it might be used for predicting the impairment of stem cell therapy of another urological condition, female stress urinary incontinence (FSUI), that affects mainly the bladder urethral sphincter [ 1 , 2 , 3 , 9 ].…”

“…This was relevant to the high prevalence of FSUI in women with T2D/O and the variable degree of efficacy of autograph stem cell therapy for this condition [ 1 , 2 , 3 ]. Female rats of the same strain as the male OZ rat model (carrying the leptin gene mutation for T2D/O) were used but they were named Zucker fatty or ZF rats to avoid confusion [ 8 ].…”