Abstract

In the past decade, depot systems for tissue engineering, cell therapy, biomedical research, and therapeutic proteins, have been extensively investigated. Hydrogels offer an interesting platform for sustained delivery of biologicals as these can be readily formulated with limited impact on their integrity and stability. Their high-water content and porous structures make them especially suitable for loading with therapeutic proteins However, relatively rapid release of the hydrophilic compounds (period of hours to days) and limited drug loading capacity (<10%) present major challenges. Cleavable cross-linker or hydrogels that respond to an external trigger such as ultrasound have been suggested as suitable alternatives. However, scale-up and cost-effective manufacturing using safe and established excipients remains a challenge and hydrogels for biologicals are at present scarcely developed beyond the clinical evaluation phases. While some commercial products are available the future of hydrogels for biologicals depends on the medical needs, the general benefit/risk balance, and overall costs.