Funding outcome

Children receiving an organ transplant need lifelong medications to prevent their immune system from attacking the foreign organ. These medications, however, cause harmful side-effects. Special immune cells, called regulatory T cells or Tregs, naturally suppress unwanted immune reactions. Clinical trials are underway to test these cells as a therapy to prevent transplant rejection. Tregs come from the thymus, a structure located in the upper chest. The thymus is routinely removed during pediatric heart surgeries as it is in the surgeon's way. We recently showed discarded thymuses to be a source of many powerful Tregs, which can be used as a cellular therapy. Having a supply of therapeutic thymic Tregs ready to use as needed would be beneficial. Cryopreservation, a freezing process, permits long-term storage of living cells. However, current cell storage protocols are not customized for therapeutic Tregs, leading to suboptimal cell number and quality after thawing. This project will investigate how Tregs harvested from thymus tissue 'react' to freezing and thawing, and explore new protocols to improve the cryopreservation process. Cells must be frozen in protective 'ice control' agents to prevent damage from ice crystals. Problematically, protective agents in current use are toxic to Tregs. To improve Treg preservation, we will test new 'ice control' agents to determine which substance is most protective and least toxic. Stopped flow fluorimetry looks at rapid changes at the cellular level. This will help determine how protective agents enter and exit cells. Interrupted freezing techniques expose Tregs to rapid and extreme temperature changes, simulating cell injury caused by freezing and thawing. These tests will aid our understanding of how to best freeze and store Treg cells. Better understanding of Treg cryopreservation techniques can help optimize cell viability and function after thawing, giving greater quantities of effective Tregs for therapeutic purposes.