The histopathologic, pharmacologic and urodynamic results of mesenchymal stem cell's injection into the decompensated rabbit's bladder.

Objectives: We researched the survival of bone marrow-derived mesenchymal stem cells (MSCs) and the results of MSCs' injected into decompensated bladders in a rabbit model.

Methods: Partial bladder neck obstruction (PBNO) and subsequent decompensation of the bladder was achieved by wrapping the bladder neck with autologous rectus fascia. In the first aspect of the experiment 18 rabbits underwent MSC injection into the decompensated bladder to prove the survivability of injected MSCs. For this purpose MSCs were isolated, transfected with Green Fluorescent Protein (GFP), and injected into the detrusor layer. Once viability was assessed in the first phase, an additional 10 rabbits underwent PBNO in the second phase. Five of these animals underwent subsequent MSC injection (group 3, stem cell) and 5 did not (group 2, obstruction). Both groups were compared to 5 controls (group 1). Urodynamics were performed in all groups. After the animals were sacrificed the groups were compared via morphometric analysis, contractile response to carbachol and KCl, and muscarinic receptor type analysis.

Results: On morphometric analysis, collagenous area rates were 43, 53 and 37% in group 1, 2 and 3, respectively. There was no statistically significant difference between groups in terms of bladder weight, bladder capacity and vesical pressure. The contractile effects of KCl and muscarinic agonist carbachol were significantly higher in groups 1 and 3 than group 2. The response to carbachol was antagonized by muscarinic M(1) and M(3) receptor antagonist pirenzepine and abolished by muscarinic M(3) receptor antagonist 4-DAMP in all groups.

Conclusions: The injection of MSCs decreased the collagenous area, increased detrusor contractility. Functional M(3) receptors were also expressed in MSCs-injected bladder smooth muscle as well as in control group.