Tissue regeneration of the vocal fold using bone marrow mesenchymal stem cells and synthetic extracellular matrix injections in rats.

To determine the effectiveness of bone marrow mesenchymal stem cell (BM-MSC) transplantation in isolation or within a synthetic extracellular matrix (sECM) for tissue regeneration of the scarred vocal fold lamina propria. In vitro stability and compatibility of mouse BM-MSC embedded in sECM was assessed by flow cytometry detection of BM-MSC marker expression and proliferation. Eighteen rats were subjected to vocal fold injury bilaterally, followed by 1 month post-treatment with unilateral injections of saline or sECM hydrogel (Extracel; Glycosan BioSystems, Inc., Salt Lake City, UT), green fluorescence protein (GFP)-mouse BM-MSC, or BM-MSC suspended in sECM. Outcomes measured 1 month after treatment included procollagen-III, fibronectin, hyaluronan synthase-III (HAS3), hyaluronidase (HYAL3), smooth muscle actin (SMA), and transforming growth factor-beta 1(TGF-beta1) mRNA expression. The persistence of GFP BM-MSC, proliferation, apoptosis, and myofibroblast differentiation was assessed by immunofluorescence. BM-MSC grown in vitro within sECM express Sca-1, are positive for hyaluronan receptor CD44, and continue to proliferate. In the in vivo study, groups injected with BM-MSC had detectable GFP-labeled BM-MSC remaining and showed proliferation and low apoptotic or myofibroblast markers compared to the contralateral side. Embedded BM-MSC in the sECM group exhibited increased levels of procollagen III, fibronectin, and TGF-beta1. BM-MSC within sECM downregulated the expression of SMA compared to BM-MSC alone and exhibited upregulation of HYAL3 and no change in HAS3 compared to saline. Treatment of vocal fold scarring with BM-MSC injected in a sECM displayed the most favorable outcomes in ECM production, hyaluronan metabolism, myofibroblast differentiation, and production of TGF-beta1. Furthermore, the combined treatment had no detectable cytotoxicity and preserved local cell proliferation.