Vitamin D and Vitamin K concentrations in human brain tissue are influenced by freezer storage time: the memory and aging project

Authors: FU, XUEYAN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; SHEA, KYLA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; DOLNIKOWSKI, GREGORY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; PATTERSON, WILLIAM - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; DAWSON-HUGHES, BESS - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; HOLLAND, THOMAS - Rush University Medical Center; SCHNEIDER, JULIE - Rush University Medical Center; BOOTH, SARAH - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2020
Publication Date: 11/28/2020
Citation: Fu, X., Shea, K., Dolnikowski, G.G., Patterson, W.B., Dawson-Hughes, B., Holland, T.M., Schneider, J.A., Booth, S.L. 2020. Vitamin D and Vitamin K concentrations in human brain tissue are influenced by freezer storage time: the memory and aging project. Journal of Nutrition. https://doi.org/10.1093/jn/nxaa336.
DOI: https://doi.org/10.1093/jn/nxaa336

Interpretive Summary: Tissue repositories have facilitated scientific discovery about the biological mechanisms underlying cognitive disease. Brain tissue samples are obtained from donors at autopsy, then frequently frozen and stored in ultra cold freezers until they are analyzed in the laboratory. Storage time can range from days to decades. Because vitamins D and K may have a role in cognitive disease, there is interest in measuring their concentrations in human brain tissue. It is important to evaluate how storage time affects the brain concentrations of these nutrients so that research findings are interpreted appropriately. We tested differences in vitamin D and vitamin K concentrations in human brain samples stored for 4 months up to 13 years. Tissue samples were obtained from 499 deceased participants in the Rush Memory and Aging Project. The vitamin D concentrations in brain stored for more than six years were a third of those stored for less than a year. The vitamin K concentrations in the brains stored over nine years was half the concentration of brains stored less than one year. Vitamins D and K appear to be stable in brain tissue samples adults stored in ultra cold freezers for up to 6 and 9 years, respectively, but not longer. These findings highlight the importance of considering freezer storage time in the design and interpretation of studies using stored brain tissue.

Technical Abstract: Background: Vitamins D and K, which are present in human brain, may have a role in neurodegenerative disease. Objectives: Given the interest in measuring nutrient concentrations in archived brain samples, it is important to evaluate whether freezer storage time affects these concentrations. Therefore, we evaluated differences in vitamin D and vitamin K concentrations in human brain samples stored for various lengths of time. Methods: Postmortem brain samples were obtained from 499 participants in the Rush Memory and Aging Project (mean age 92 y, 72% female). Concentrations of vitamins D, K, and their metabolites, were measured in 4 regions (midtemporal cortex, midfrontal cortex, cerebellum, anterior watershed white matter) using LC-MS/MS and HPLC, respectively. The predominant forms were 25-hydroxycholecalciferol [25(OH)D3] and menaquinone-4 (MK4). ANOVA was used to determine if concentrations differed according to storage time. Results: The geometric mean of the mean 25(OH)D3 concentration (across 4 regions) in brains stored for 1.1 to 6.0 y did not differ from that in brains stored <=1.0 y (all p >=0.37), whereas 25(OH)D3 in brains stored >6.0 y was 31-40% lower (p<=0.003). MK4 had similar results, with the geometric mean MK4 concentration in the brains stored >=9.0 y being 48-52% lower than those in brains stored <=1.0 y (p <=0.012). The 25(OH)D3 and MK4 concentrations were positively correlated across all 4 regions (all Spearman rho >=0.79, p<0.001). Conclusions: 25(OH)D3 and MK4 appear to be stable in brain tissue from older adults stored at -80oC for up to 6 and 9 y, respectively, but not longer. Freezer storage time should be considered in the design and interpretation of studies using archived brain tissue.