Breathing life into engineered tissues using oxygen-releasing biomaterials

Engineering three-dimensional (3D) tissues in clinically relevant sizes have demonstrated to be an effective solution to bridge the gap between organ demand and the dearth of compatible organ donors. A major challenge to the clinical translation of tissue-engineered constructs is the lack of vasculature to support an adequate supply of oxygen and nutrients post-implantation. Previous efforts to improve the vascularization of engineered tissues have not been commensurate to meeting the oxygen demands of implanted constructs during the process of homogeneous integration with the host. Maintaining cell viability and metabolic activity during this period is imperative to the survival and functionality of the engineered tissues. As a corollary, there has been a shift in the scientific impetus beyond improving vascularization. Strategies to engineer biomaterials that encapsulate cells and provide the sustained release of oxygen over time are now being explored. This review summarizes different types of oxygen-releasing biomaterials, strategies for their fabrication, and approaches to meet the oxygen requirements in various tissue engineering applications, including cardiac, skin, bone, cartilage, pancreas, and muscle regeneration. Tissue engineering: Innovative packaging ensures new cells breathe easy Biomaterials that surround artificial tissue and slowly release oxygen can improve survival rates during wound healing and organ regeneration trials. Although researchers have successfully constructed many kinds of tissues using 3D scaffolds, supplying the cells with adequate oxygen and nutrients post-implantation remains challenging. Gulden Camci-Unal from the University of Massachusetts Lowell in the USA and colleagues review how microscale oxygen sources such as calcium peroxide crystals are being combined with flow-regulating polymers to keep engineered tissues healthy until vascular systems are established. Coatings of peroxides and polymers applied to 3D scaffolds, for example, strengthen bone cultures by releasing a steady supply of oxygen to permeate throughout the tissue for extended times. Byproducts from oxygen-releasing materials can also be used to inhibit biofilm growth on implants, lessening chances of infection. The inability to administer oxygen in a controlled and sustained manner into thick artificial tissues has attracted a growing interest towards the design and development of new functional biomaterials. Without a sufficient oxygen supply, tis