Impact of modified gelatin on valvular microtissues

Area of Science:

• Tissue Engineering and Regenerative Medicine
• Biomaterials Science
• 3D Bioprinting and Biofabrication

Background:

• Fabricating functional three-dimensional (3D) tissues for organ-on-a-chip systems and organ engineering remains a significant challenge.
• Multicellular valvular microtissues serve as foundational units for constructing larger valvular macrotissues.
• Controlled biofabrication of 3D macrotissues with complex, predefined shapes necessitates directed assembly of microtissues via bioprinting.

Purpose of the Study:

• To evaluate modified gelatin as an instructive biomaterial for the biofabrication of valvular microtissues.
• To assess the impact of modified gelatin encapsulation on valvular interstitial cell function and extracellular matrix (ECM) production.
• To demonstrate the potential of modified gelatin for creating larger valvular tissues through microtissue assembly.

Main Methods:

• Valvular microtissues were encapsulated within modified gelatin hydrogels, cross-linked using photoinitiators (Irgacure 2959 or VA-086).
• Hydrogel properties were characterized, and cellular functions (phenotype, proliferation, migration, ECM gene expression, ECM deposition, tissue fusion) were analyzed using histochemical staining and RT-qPCR.
• Comparison of encapsulated versus non-encapsulated microtissues was performed to understand the material's influence.

Main Results:

• Encapsulated microtissues maintained viability, produced key ECM components, and remained quiescent.
• Encapsulation altered ECM formation and gene expression, leading to lower remodeling capacity and increased expression of specific ECM molecules (Col I/V, elastin, hyaluronan, biglycan, decorin) and Sox9.
• Softer hydrogel formulations promoted enhanced proliferation, migration, and tissue fusion of the encapsulated microtissues.

Conclusions:

• Modified gelatin demonstrates instructive properties for developing physiologically relevant valvular microtissues.
• The study provides proof of concept for forming larger valvular tissues by assembling microtissues within soft modified gelatin gels.
• This approach holds promise for advancing organ-on-a-chip technologies and future organ engineering endeavors.