Neonatal and Young Pediatric Kidney Preservation through Nanowarming and Vitrification

ABSTRACT The kidney transplant waitlist comprises 83% of the U.S. organ transplant waitlist- yet, for every 5 waitlist patients who die, or become too sick for transplantation, 3 potentially transplantable kidneys are discarded. Infants and small children on the waitlist have a higher organ discard rate than adults due to locality and timeframe constraints. Extending and improving kidney preservation would enable nationwide (eventually global) donor-recipient matching for these young children and also allowing additional good quality kidneys not transplanted today to be offered to older patients. Long duration kidney preservation can also enable translation of clinical immune tolerance induction avoiding life-long immunosuppression. Using effective cryoprotective agents (CPAs) our team and others have successfully cryopreserved tissues in an ice-free vitreous “glassy” state, allowing for indefinite storage. Unfortunately, these advances had not been matched by similar advances to prevent damage from ice growth and/or fracturing during rewarming. Recently, our co-PIs Dr. Finger and Dr. Bischof demonstrated a scalable and biocompatible nanowarming technology using radiofrequency (RF)-excited iron oxide nanoparticles (IONPs) for ice and fracture avoidance during rewarming from cryogenic storage. The nanowarming technology led to the successful completion of our Phase I study resulting in: 1) optimized CPA selection, permeation, and critical cooling and warming rates for kidney slices, and 2) established vitrification and nanowarming for whole rat and, beyond the initial Phase I scope, rabbit kidneys. Subsequently, Dr. Bischof’s team has demonstrated the world’s first and only, successful, repeat transplants of mammalian kidneys after cryogenic preservation. Building on this unprecedented achievement and the Phase I feasibility success, we here scale-up and apply this new technology to neonatal and pediatric kidney preservation, where the physics of heat transfer make it exponentially less challenging to cryopreserve smaller (younger) organs compared to adult organs. Our goal will be achieved via 3 Aims: 1) vitrification and nanowarming of whole juvenile porcine model kidney with i) optimization of pediatric size kidney vitrification protocols as well as ii) identification of potential mechanism(s) of any remaining injury, 2) optimization of vitrification cocktails and perfusion protocols for neonate, infant, and small children human kidneys, with (i) biocompatible cryostasis cocktails and (ii) effective revival/reconditioning protocols for enhanced reperfusion, 3) orthotopic survival autotransplantation with long-term survival, with the best protocols from SA 1-2 and compared via current ex vivo clinical assessment practices ahead of proof of concept for 100+ days storage and transplantation in juvenile pigs, and human decedent recipients. Altogether, this constitutes an important standalone project enabling further breakthroughs in biopreservation, tissue engineering, biomedical research, and clinical practice. This will set the stage for our logistical model of centralized centers of excellence for preservation and assessment, enabling vastly improved clinical outcomes and patients’ access globally.