Hydrogels for cardiac tissue engineering

Cardiac failure is a critical condition that results in life-threatening consequences. Due to a limited number of organ donors, tissue engineering has emerged to generate functional tissue constructs and provide an alternative mean to repair and regenerate damaged heart tissues. In this paper, we review the emerging directions associated with cardiac tissue engineering approaches. In particular, we discuss the use of hydrogels in repair and regeneration of damaged hearts. Because of their tissue-like biological, chemical and mechanical properties, hydrogels represent a potentially powerful material for directing cells into functional cardiac tissues. Herein, we will summarize both traditional and next-generation hydrogels with conductive, elastomeric and oxygen-releasing capabilities that can promote vascularization and stem cell differentiation to form properly functioning cardiac tissues. Hydrogel-based scaffolds are promising biomaterials to deliver cells and small biomolecules to regenerate the cardiac muscle. It is anticipated that cell-loaded hydrogels will potentially be able to mend the broken heart. Cardiac tissue damaged after a heart attack is particularly difficult to regenerate. Consequently, researchers are exploring innovative ways to regrow cells in this stressful and oxygen-rich microenvironment. Ali Khademhosseini and colleagues from Harvard Medical School in the United States review recent efforts to create biocompatible scaffolds for cardiac tissue engineering using hydrogels - squishy, three-dimensional polymer networks that expand in water, much like natural tissue. While cardiac cells grown on traditional hydrogel supports such as poly(ethylene glycol) and fibrils have considerably higher viability than those directly injected into cardiac muscle, novel hydrogels that better mimic native heart functions are still needed. The researchers highlight enhanced biomaterials incorporating elastomeric, conductive and oxygen-releasing capabilities. Furthermore, they anticipate that combining renewable stem cells with micropatterning techniques could enable the development of prevascularized, ‘off-the-shelf’ hydrogels that are ready to be implanted into patients.