Adipose derived stem cells ameliorate hyperlipidemia associated detrusor overactivity in a rat model

Abstract

Purpose: Adipose tissue derived stem cells can differentiate into muscle and neuron-like cells in vitro. We investigate the usefulness of adipose tissue derived stem cells for overactive bladder in obese hyperlipidemic rats.

Materials and methods: Hyperlipidemia was induced in healthy rats by a high fat diet. The resulting obese hyperlipidemic rats were treated with bladder injection of saline, adipose tissue derived stem cells or tail vein injection of adipose tissue derived stem cells. Bladder function was assessed by 24-hour voiding behavior study and conscious cystometry. Bladder histology was assessed using immunostaining and trichrome staining, followed by image analysis.

Results: Serum total cholesterol and low density lipoprotein were significantly higher in obese hyperlipidemic rats than in normal rats (p <0.01). The micturition interval was shorter in saline treated obese hyperlipidemic rats than in normal rats, obese hyperlipidemic rats that received adipose tissue derived stem cells via the tail vein and obese hyperlipidemic rats that received adipose tissue derived stem cells by bladder injection (mean +/- SEM 143 +/- 28.7 vs 407 +/- 77.9, 281 +/- 43.9 and 368 +/- 66.7 seconds, respectively, p = 0.0084). Bladder wall smooth muscle content was significantly lower in obese hyperlipidemic rats than in normal animals (p = 0.0061) while there was no significant difference between obese hyperlipidemic groups. Nerve content and blood vessel density were lower in controls than in obese hyperlipidemic rats treated with adipose tissue derived stem cells.

Conclusions: Hyperlipidemia is associated with increased urinary frequency, and decreased bladder blood vessel and nerve density in rats. Adipose tissue derived stem cell treatment ameliorates these adverse effects and holds promise as a potential new therapy for overactive bladder.

Figure 1

Representative cystometry curves in (A) normal bladder cystometry and in (B) OAB. The blue upper, red middle and green lower panel present bladder, intra-abdominal and detrusor contraction pressure, respectively. The light blue, lowest panel presents the accumulated micturition volume. The micturition pattern was recorded for 30 min. OAB was defined by shorter micturition intervals and smaller micturition volume per void.

Figure 2

Tracking transplanted ADSC. The bladder was stained with Alexa-594 (red fluorescence), DAPI (blue fluorescence) and anti-α-SMA antibody (green fluorescence). Only EdU-positive cells show red fluorescence (arrow). No EdU-positive cell were identified in normal (A,B) and OHR (C,D) that received PBS by injection. Several EdU-positive cells were identified in the muscular layer of the rats that received ADSC transplantation via tail vain injection (E, F). A greater concentration of EdU-positive cells was noted in the rats that received ADSC injection directly into bladder relative to those that received ADSC by tail vein injection. (G, H). Magnification is X 100 for Fig. A, C, E and G, and x 400 for Fig. B, D, F and H.

Figure 3

Blood vessel content of bladder wall. RECA-1 staining of bladder wall from a rats fed a normal diet that received PBS (A), a high-fat diet that received PBS (B), a high-fat diet with ADSC transplantation via tail vein (C) and a high-fat diet with ADSC injection into bladder (D). The endothelium of blood vessels is stained brown (arrow). The number of RECA-1 positive cells was higher in figures A, C and D relative to B. Magnification is X 100.

Figure 4

Nerve content of bladder wall. ChAT staining of bladder wall from a rat fed a normal diet that received bladder injection of PBS (A), a rat fed a high-fat diet that received bladder injection of PBS (B), a rat fed a high-fat diet that received tail vein injection of ADSC (C) and a rat fed a high-fat diet that received bladder injection of ADSC (D). Choline acetyltransferase positive tissue is stained brown (arrow). The number of ChAT staining cholinergic nerves in the bladder wall was high in A, C and D, but not in B. Magnification is X 400.

Figure 5

Smooth muscle content of the bladder wall. Masson’s trichrome staining of bladder wall from a rat fed a normal diet that received bladder injection of PBS (A), a rat fed a high-fat diet that received bladder injection of PBS (B), a rat fed a high-fat diet that received tail vein injection of ADSC (C) and a rat fed a high-fat diet that received bladder injection of ADSC (D). Smooth muscle is stained red and connective tissue blue. The smooth muscle content was higher in A than in B, C and D. Magnification is X 100.