Survival and Proliferation under Severely Hypoxic Microenvironments Using Cell-Laden Oxygenating Hydrogels

Abstract

Different strategies have been employed to provide adequate nutrients for engineered living tissues. These have mainly revolved around providing oxygen to alleviate the effects of chronic hypoxia or anoxia that result in necrosis or weak neovascularization, leading to failure of artificial tissue implants and hence poor clinical outcome. While different biomaterials have been used as oxygen generators for in vitro as well as in vivo applications, certain problems have hampered their wide application. Among these are the generation and the rate at which oxygen is produced together with the production of the reaction intermediates in the form of reactive oxygen species (ROS). Both these factors can be detrimental for cell survival and can severely affect the outcome of such studies. Here we present calcium peroxide (CPO) encapsulated in polycaprolactone as oxygen releasing microparticles (OMPs). While CPO releases oxygen upon hydrolysis, PCL encapsulation ensures that hydrolysis takes place slowly, thereby sustaining prolonged release of oxygen without the stress the bulk release can endow on the encapsulated cells. We used gelatin methacryloyl (GelMA) hydrogels containing these OMPs to stimulate survival and proliferation of encapsulated skeletal myoblasts and optimized the OMP concentration for sustained oxygen delivery over more than a week. The oxygen releasing and delivery platform described in this study opens up opportunities for cell-based therapeutic approaches to treat diseases resulting from ischemic conditions and enhance survival of implants under severe hypoxic conditions for successful clinical translation.

Injectable Self‐Oxygenating Cardio‐Protective and Tissue Adhesive Silk‐Based Hydrogel for Alleviating Ischemia After Mi Injury

“…We previously reported that OMPs-laden hydrogels alleviated anoxic stress in hydrogel-encapsulated hMSCs and significantly improved vascularization by increased VEGF secretion under anoxic conditions. [17,19,48] To study the alleviation of anoxic injury in response to MI, we assessed a combinatorial effect of hypoxic chemotaxis through the application of SDF to populate an anoxic cell-dead area with circulating stem cells, followed by hypoxic mediation to induce vascularization through OMP encapsulation in silk-based tissue adhesive hydrogels. As a first step, OMPs were synthesized using calcium peroxide (CPO) and polycaprolactone (PCL) following our previously developed protocols through a controllable and scalable water-in-oil-in-water double emulsion synthesis method.…”

“…We recently reported on the role of oxygen-releasing microparticles (OMPs) in the improvement of angiogenic/vasculogenic properties in human mesenchymal stem cell (hMSC)-laden engineered tissues under anoxic conditions via improved viability and paracrine effect of hMSCs in vitro and in vivo. [16][17][18][19] Since SDF is a chemokine secreted by hMSCs, we expect a combinatorial effect of SDF and OMPs to improve angiogenesis at the infarct site in an MI condition. It is, therefore, intuitive to locally alleviate hypoxic stress while reducing the vascularization time via cardioprotective and oxygenating hydrogels that are mechanically robust and biodegradable to eventually improve the survival and function of recruited cells at the injured area.…”

Engineering Antioxidant and Oxygen-Releasing Lignin Composites to Promote Wound Healing

“…Injectable cryogels are formed with methacrylated hyaluronic acid and CaO 2 [89]. Cumulative release of H 2 O 2 is up to 468 μmol over 3 h. Microparticles (MPs) are formed with the encapsulation of CaO 2 in PCL, then formed composites with GelMA[90] and release O 2 up to 5 weeks[91]. Over 2 weeks, 2.5 μM of H 2 O 2 is released without the formation of MPs while 1.0 μM with the formation of MPs.…”

Injectable Antioxidant and Oxygen-Releasing Lignin Composites to Promote Wound Healing

“…A recent study utilized microparticles (MPs) formed with the encapsulation of CaO 2 in PCL (polycaprolactone). These particles are incorporated in composites with GelMA 39 and release O 2 for up to 5 weeks. 40 Over 2 weeks, 2.5 μM of H 2 O 2 is released without the formation of MPs, whereas 1.0 μM of H 2 O 2 is released with the formation of MPs.…”