Use of the TLX ultracentrifuge for the isolation of different density lipoproteins and effects of freeze/thawing of human plasma before ultracentrifugation

BACKGROUND: Isolation of different density lipoproteins by ultracentrifugation can require lengthy centrifugation times and freeze/thawing of plasma may influence recovery. METHODS: We isolated a range of lipoproteins using a preparative ultracentrifuge and the TLX micro-ultracentrifuge and determined the effect of freeze/thawing of plasma beforehand. RESULTS: In fresh plasma, there was no significant difference in results for small-dense low-density lipoprotein apolipoprotein B (LDL apoB) (density >1.044 g/mL) or cholesterol at density >1.006 g/mL. Freeze/thawing had no effect on closely correlated results for small-dense LDL apoB (r=0.85; p<0.0001) or high-density lipoprotein (r=0.93; p<0.0001). CONCLUSIONS: The TLX micro-ultracentrifuge is a reliable alternative to the preparative ultracentrifuge and freeze/thawing has only a small effect on small-dense LDL apoB or high-density lipoprotein cholesterol.