PNIPAAm-based biohybrid injectable hydrogel for cardiac tissue engineering

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Cardiovascular Engineering

Background:

• Injectable biomaterials are crucial for non-invasive cardiac cell delivery.
• Existing injectable matrices often lack sufficient bioactivity and mechanical strength.
• Developing advanced hydrogels is essential for effective cardiac tissue regeneration.

Purpose of the Study:

• To synthesize and characterize a novel biohybrid, temperature-responsive injectable hydrogel for cardiac tissue engineering.
• To evaluate the bioactivity, mechanical properties, and cell-supporting capabilities of the hydrogel in vitro.
• To assess the functionality of encapsulated cardiomyocytes and cardiac fibroblasts in mono- and co-culture conditions.

Main Methods:

• Synthesis of a poly(N-isopropylacrylamide) (PNIPAAm)-Gelatin-based injectable hydrogel.
• In vitro assessment of hydrogel viscoelasticity, water content, and mechanical robustness.
• Encapsulation and culture of cardiomyocytes (CMs) and cardiac fibroblasts (CFs) within the hydrogel.
• Evaluation of cell viability, spreading, F-actin formation, and phenotypic characteristics using immunostaining and gene expression analysis.
• Assessment of cell-cell coupling and contractile behavior in co-culture conditions.

Main Results:

• The synthesized hydrogel demonstrated viscoelastic behavior (storage modulus: 1260 Pa) and optimal water content (75%).
• High cell survival (90% for co-culture) and excellent cell spreading were observed within the 3D matrix.
• Encapsulated cardiac cells exhibited mature phenotypic characteristics and formed a dense, integrated network.
• Co-cultures showed superior structural organization, cell-cell coupling, and synchronized beating (∼45 beats per min).

Conclusions:

• A novel biohybrid PNIPAAm-Gelatin injectable hydrogel was successfully synthesized for cardiac tissue engineering.
• The hydrogel possesses suitable bioactivity and mechanical properties to support cardiac cell encapsulation and function.
• Extensive in vitro analyses confirmed the hydrogel's potential for promoting cardiac cell survival, organization, and functionality, especially in co-culture settings.
• This study provides a robust platform for in vitro characterization of injectable cardiac cell-laden matrices prior to in vivo applications.