| We are interested in developing stem cell-based tissue engineering methodology for the restoration of vocal fold functions. Successful engineering of vocal fold tissues relies on the strategic combination of multipotent cells, biomimetic scaffolds, physiologically relevant mechanical and biochemical cues. In our initial investigations, we sought to regulate the fibroblastic commitment of mesenchymal stem cells (MSCs) via the combination of connective tissue growth factor (CTGF) and a composite microfibrous scaffold based on poly(glycerol sebacate) (PGS) and poly(epsilon-caprolactone) (PCL). MSCs maintained their fibroblastic morphology and infiltrated deeper into the scaffold following 21 days of CTGF treatment. The addition of CTGF led to enhanced cell proliferation, upregulated fibroblastic hallmarks, as well as elevated deposition of vocal fold essential extracellular matrix (ECM). Diminished mesenchymal surface markers were induced upon CTGF treatment, without triggering the potential of undesirable differentiation or apoptosis. Separately, we have successfully constructed and characterized a bioreactor capable of imposing physiologically relevant vibratory stimulations to the cultured cells. MSC-laden PCL scaffolds were incorporated into the bioreactor and were subjected to high frequency vibrations at 200 Hz for a week. Our results suggest that the fibrous scaffolds created a vocal fold-like niche allowing MSCs to respond to the vibrations via an integrin-mediated mechanotransduction mechanism. The vibrations were efficacious to modulate the behaviors of MSCs, to facilitate their essential ECM synthesis and the adaptation of fibroblastic phenotype. Furthermore, the vibrations and CTGF were sequentially introduced to the MSC-laden PCL constructs. The two factors appeared to cooperatively mediate MSC functions, leading to an accelerated ECM synthesis and balanced ECM remodeling; and the classical Erk1/2 pathway was critically engaged in the mechano-biochemical cooperation. In brief, our study underscores the significance of reproducing a physiologically relevant microenvironment to modulate stem cell behaviors for successful functional vocal fold assembly in vitro. |
