Inkjet bioprinting of solid peroxides for constructing oxygen generating scaffolds to improve cells viability and growth under hypoxic environment
Tissue engineering has emerged as an interdisciplinary field to overcome current challenges for tissue repair or replacement in the human body. In essence, it proposes new medical therapies customized to match the biology of specific patients. The potential benefits offered by tissue engineering have driven scientific inquiry to make it a clinical reality. One of the current challenges in tissue engineering is to provide oxygen supply to thick tissues as oxygen diffusion is limited to 100 - 200 µm layer of viable tissue. Engineered vascular conduits are applied in vitro, providing pre-vascularization to tissues; however, host anastomosis is still a problem. Biomaterials are suggested as another strategy; the aim is to construct scaffolds able to provide oxygen to cells in a controlled manner. Tissues require a controlled progressive oxygen supply, otherwise hypoxia or hyperoxia could induce cell necrosis. Inkjet printing method was developed to dispense living organisms, or biomaterials using a designed pattern. The hypothesis tested in this study is that scaffolds can be developed to provide a controlled oxygen supply thereby enhancing cell viability in hypoxic environments. Calcium peroxide (CaO2) was selected as oxygen generating material. It was encapsulated in alginate hydrogels to provide a continuous oxygen supply. Inkjet printed microparticles of CaO2 were evaluated under hypoxic environment (0.01 mol/m3 O2) in direct contact with culture medium. Samples with a ratio of 2 mg/mL (CaO2/medium) exhaust the oxygen supply after 30 hours. Oxygen generating scaffolds fabricated with a ratio of 160 mg of alginate per 10 mg of CaO2 provided a stable oxygen supply in the range of 0.066 - 0.052 mol/m3 under hypoxic environment. Fibroblast L-cells were cultured for 120 hours on these scaffolds under hypoxia (0.01 mol/m3, 5% CO2, 37 ºC) and their viability was evaluated via MTS metabolic assay. Statistical differences between oxygenized scaffolds and negative control scaffolds were observed. Live/Dead assays corroborated these results. The current study shows a scaffold composed of alginate-hydrogel, and CaO2 microparticles dispensed by the inkjet printing technology, able to supply oxygen in contact with culture medium. The oxygen generating scaffold was capable of maintaining cell mitochondrial activity under hypoxic conditions. The inkjet printing method may play an important role to construct complex scaffolds for tissue engineering applications, where the diffusion of oxygen is a constraint for large engineered-tissue implants.
Reyna Soriano, Daniel, "Inkjet bioprinting of solid peroxides for constructing oxygen generating scaffolds to improve cells viability and growth under hypoxic environment" (2014). ETD Collection for University of Texas, El Paso. AAI3636300.