Perfusion bioreactor-based cryopreservation of 3D human mesenchymal stromal cell tissue grafts.

The generation of an off-the-shelf in vitro engineered living tissue graft will likely require cryopreservation. However, the efficient addition and removal of cryoprotective agents (CPA) to cells throughout the volume of a three-dimensional (3D) tissue graft remains a significant challenge. In this work, we assessed whether a perfusion bioreactor-based method could be used to improve the viability of cryopreserved mesenchymal stromal cell- (MSC) based tissue constructs as compared to using conventional diffusion-based methods. The bioreactor was first used to saturate 3D constructs with CPA under perfused flow. Following cryopreservation, the bioreactor was then also used for the efficient removal of the CPA from the 3D tissues. We demonstrate that addition and removal of CPA under perfused flow significantly increased the viability of MSC within cryopreserved 3D tissue constructs as compared to conventional diffusion-based methods.

Training stem cells for treatment of malignant brain tumors.

The treatment of malignant brain tumors remains a challenge. Stem cell technology has been applied in the treatment of brain tumors largely because of the ability of some stem cells to infiltrate into regions within the brain where tumor cells migrate as shown in preclinical studies. However, not all of these efforts can translate in the effective treatment that improves the quality of life for patients. Here, we perform a literature review to identify the problems in the field. Given the lack of efficacy of most stem cell-based agents used in the treatment of malignant brain tumors, we found that stem cell distribution (i.e., only a fraction of stem cells applied capable of targeting tumors) are among the limiting factors. We provide guidelines for potential improvements in stem cell distribution. Specifically, we use an engineered tissue graft platform that replicates the in vivo microenvironment, and provide our data to validate that this culture platform is viable for producing stem cells that have better stem cell distribution than with the Petri dish culture system.