The Effects of DMSO Cryopreservation on the Biomechanics and Histology of Human Cerebrovascular Tissue

IntroductionTissue preservation techniques, chiefly cryopreservation, have been demonstrated to alter vascular histology and tissue biomechanics via rapid osmotic change--resulting in collagen fiber rearrangement and internal elastic laminae (IEL) microfractures; however, this has not yet been evaluated in cerebrovascular tissue. As such, we sought to measure the effectiveness of a canonical cryopreservation strategy on the thickness and continuity of human cerebrovascular tissue. With the recent rise in biomechanical analyses of cerebrovascular tissue for the design of novel treatments and optimization of surgical strategies, the importance of designing models with accurate tissue proxies is paramount. MethodsFresh, human cerebrovascular tissue was obtained through the Cleveland Clinic institutional cadaver donation program. Donors with prior craniotomy, intracranial malignancy, or history of cerebrovascular disease were excluded. Cadaveric tissue dissections were completed within fourteen days of patient expiration and sectioned into four specimens. The 164 tissue samples obtained from three donors were then randomized into one of the following experimental conditions: 10% formalin (control), distilled water (dH2O), dimethyl sulfoxide (DMSO), or -80 {degrees}C DMSO cryopreservation. Specimens were then processed into paraffin-embedded sections and treated with Movat pentachrome staining. Vessel layers were measured by two blinded evaluators and discontinuities in internal elastin lamina were tallied. ResultsWe found that DMSO cryopreservation failed to consistently provide a protective effect to cerebrovascular specimens. Tissue stored via this method was reported to occasionally swell in specific vessel tunics of select vessel territories compared to formalin controls. We also observed an increase in the number of transverse elastin breaks with DMSO cryopreservation. ConclusionsThis data demonstrates that conventional tissue preservation methods may fail to preserve layer thicknesses between some vessels and alter biomechanical properties for future testing. Further, with more frequent elastin fractures in the cryopreservation group, recoilability of preserved vessels may vary from in vivo counterparts. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=130 SRC="FIGDIR/small/679363v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@1d8cc51org.highwire.dtl.DTLVardef@4ddcd6org.highwire.dtl.DTLVardef@1dd94f1org.highwire.dtl.DTLVardef@5d99bf_HPS_FORMAT_FIGEXP M_FIG C_FIG