Mobile Cryopreservation of Vascular Allografts in Polydimethylsiloxane

Aim To develop a scheme for allografts cryopreservation right after their retrieval from cadaver donors with possible repeated allograft cryopreservation. Materials and Methods For conducting a pilot experiment, 11 cadaveric femoral arterial segments were retrieved and divided into four groups including control. Polydimethylsiloxane (PDMS) was used as heat/cool transfer fluid and potential cryoprotectant. Preliminary heat transfer mathematical modeling was performed with use of allografts phantoms. Based on preliminary calculations, femoral segments were placed on sterile hollow plastic tubes and cryopreserved by following protocol: groups 1 and two were immersed in polydimethylsiloxane and cooled rapidly at 180C/min to -75C with additionally repeated cryopreservation. Group 3 slices were cryopreserved slowly at 1,6 C/min in polydimethylsiloxane – filled cryo-container placed in the freezer at -80 oC. All slices were thawed by immersion in polydimethylsiloxane at +24C. After thawing the slices’ morphology was assessed by histological methods and scanning electron microscopy (EVO LS10, Carl Zeiss). Energy dispersive spectrometry analysis with the use of AzTech software also was performed for Si – content evaluation. Restricted biomechanical tests were conducted for group 2 slices by pricking their layers with the sapphirine plunger in three different directions with use of the experimental device. Results There were no any significant histological differences between controls, groups 1 and 2 with an exclusion for group 3 (with slow cryopreservation). Conclusion Mobile cryopreservation in polydimethylsiloxane is feasible for instant processing of vascular allografts for their use as tissue-specific scaffolds in tissue-engineering or for their biobanking, but it requires further study and clinical trials.