Advancements in the Field of Protein-Based Hydrogels: Main Types, Characteristics, and Their Applications.

Regenerative medicine is a challenging field in current research and development, whilst translating the findings of novel tissue regenerative agents into clinical application. Protein-based hydrogels are derived from various sources, with animal-derived products being primarily utilized to deliver cells and promote cell genesis and proliferation, thereby aiding in numerous indications, including bone tissue regeneration, cartilage regeneration, spinal cord injury, and wound healing. As biocompatible and biodegradable systems, they are tolerated by the human body, allowing them to exert their beneficial effects in many indications. In this review article, multiple types of animal-derived proteins (e.g., collagen, gelatin, serum albumin, fibrin) were described, and a selection of the recent literature was collected to support the claims behind these innovative systems. During the literature review, special indications were found when applying these hydrogels, including the therapeutic option to treat post-myocardial infarct sites, glaucoma, and others. Maintaining their structure and mechanical integrity is still challenging. It is usually solved by adding (semi)synthetic polymers or small molecules to strengthen or loosen the mechanical stress in the hydrogel's structure. All in all, this review points out the potential application of value-added delivery systems in regenerative medicine.