Regulation of Stem Cell Function in an Engineered Vocal Fold-Mimetic Environment

Area of Science:

• Biomaterials Engineering
• Regenerative Medicine
• Tissue Engineering

Background:

• Human mesenchymal stem cells (hMSCs) show promise for treating vocal fold (VF) scarring.
• Understanding how hMSCs interact with the vocal fold lamina propria (LP) extracellular matrix (ECM) is crucial for optimizing cell-based therapies.
• Current knowledge on these interactions and their impact on stem cell behavior is limited.

Purpose of the Study:

• To develop an in vitro platform simulating the vocal fold microenvironment for hMSC culture.
• To investigate the effects of dynamic mechanical stimulation on hMSCs within an LP-mimetic matrix.
• To assess the potential of mechanical loading to modulate hMSC behavior and prevent fibrosis.

Main Methods:

• hMSCs were encapsulated in a hyaluronic acid (HA), poly(ethylene glycol) (PEG), and collagen-based hydrogel mimicking the LP ECM.
• A custom vocal fold bioreactor applied dynamic mechanical stimulation (200 Hz) to the 3D cell-laden constructs.
• Characterization involved rheology, laser Doppler vibrometry (LDV), digital image correlation (DIC), and finite element analysis (FEA).
• Cellular response was evaluated by assessing viability, c-Fos upregulation, fibrogenic markers, and alpha smooth muscle actin (αSMA) expression.

Main Results:

• The bioreactor system successfully replicated vocal fold mechanical conditions, with LDV showing 47 μm displacement at 200 Hz.
• FEA predicted strains within the hydrogel consistent with native vocal fold tissue.
• Optimized vibrational stimulation (1h) led to maximal c-Fos upregulation.
• 3-day vibrational culture (1h on/1h off) maintained cell viability but significantly downregulated fibrogenic markers and αSMA expression.

Conclusions:

• Dynamic mechanical loading in a vocal fold bioreactor can prevent hMSCs from adopting a fibrotic phenotype.
• High-frequency mechanical stimulation promotes a shift away from myofibrogenic potential in hMSCs.
• This approach offers a novel strategy to enhance the efficacy of hMSC-based therapies for vocal fold scarring by controlling stem cell differentiation.