title: Cryoprotectant kinetic analysis of a human articular cartilage vitrification protocol.
abstract: We recently published a protocol to vitrify human articular cartilage and a method of cryoprotectant removal in preparation for transplantation. The current study's goal was to perform a cryoprotectant kinetic analysis and theoretically shorten the procedure used to vitrify human articular cartilage. First, the loading of the cryoprotectants was modeled using Fick's law of diffusion, and this information was used to predict the kinetics of cryoprotectant efflux after the cartilage sample had been warmed. We hypothesized that diffusion coefficients obtained from the permeation of individual cryoprotectants into porcine articular cartilage could be used to provide a reasonable prediction of the cryoprotectant loading and of the combined cryoprotectant efflux from vitrified human articular cartilage. We tested this hypothesis with experimental efflux measurements. Osteochondral dowels from three patients were vitrified, and after warming, the articular cartilage was immersed in 3 mL X-VIVO at 4 °C in two consecutive solutions, each for 24 h, with the solution osmolality recorded at various times. Measured equilibrium values agreed with theoretical values within a maximum of 15% for all three samples. The results showed that diffusion coefficients for individual cryoprotectants determined from experiments with 2-mm thick porcine cartilage can be used to approximate the rate of efflux of the combined cryoprotectants from vitrified human articular cartilage of similar thickness. Finally, Fick's law of diffusion was used in a computational optimization to shorten the protocol with the constraint of maintaining the theoretical minimum cryoprotectant concentration needed to achieve vitrification. The learning provided by this study will enable future improvements in tissue vitrification.
authors.affiliation: Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 1H9, Canada.
authors.forename: Nadia
authors.initials: N
authors.lastname: Shardt
authors.affiliation: Department of Surgery, University of Alberta, Edmonton T6G 2B7, Canada.
authors.forename: Khaled K
authors.initials: KK
authors.lastname: Al-Abbasi
authors.affiliation: Department of Surgery, University of Alberta, Edmonton T6G 2B7, Canada.
authors.forename: Hana
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Surgery, University of Alberta, Edmonton T6G 2B7, Canada.
authors.forename: Nadr M
authors.initials: NM
authors.lastname: Jomha
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton T6G 2R7, Canada.
authors.forename: Locksley E
authors.initials: LE
authors.lastname: McGann
authors.affiliation: Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 1H9, Canada; Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton T6G 2R7, Canada. Electronic address: janet.elliott@ualberta.ca.
authors.forename: Janet A W
authors.initials: JA
authors.lastname: Elliott
mesh_terms: D000818:Animals; D002358:Cartilage, Articular; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004058:Diffusion; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008962:Models, Theoretical; D013552:Swine; D058989:Vitrification
chemical_list: D003451:Cryoprotective Agents
keywords: Articular cartilage; Cryopreservation; Diffusion; Efflux; Fick’s law; Vitrification