SMN protein stability in whole blood: short term, long term, and freeze / thaw events.

<p>Whole blood of healthy subjects was used in the study. (A) SMN protein was measured in previously frozen, undiluted whole blood samples incubated at 4°C or at room temperature. (B) SMN protein was measured in undiluted whole blood samples of two subjects stored at -80°C or at -20°C. (C) SMN protein levels were measured in samples of two subjects that went through freeze-thaw cycles. *FDA acceptance criteria (below 85%).</p

SMN only detected in cerebral spinal fluid samples containing hemoglobin.

<p>The CSF samples obtained from healthy volunteers were concentrated prior to analysis, and the sensitivity of the SMN-ECL immunoassay was 0.3 pg/mL. Hemoglobin was measured using a hemoglobin immunoassay (Bethyl Laboratories E88-135). Approximately 3 pg of SMN correspond to 10,000 ng of hemoglobin in 1 mL of whole blood from a healthy adult. LLQ: lower limit of quantification.</p

Correlation of SMN protein levels between tissues.

<p>SMN protein levels were correlated in WT and C/C-allele SMA mice between (A) whole blood and brain and (B) whole blood and spinal cord.</p

SMN protein levels in tissues of C/C-allele and WT mice measured by SMN-ECL and SMN-ELISA.

<p>Protein levels were measured in the spinal cord of C/C-allele and WT mice using (A) SMN-ECL and (B) SMN-ELISA. Both assays showed a statistically significant difference in SMN levels between WT and C/C-allele mice (p < 0.0001). (C) SMN protein levels in the whole blood of C/C-allele, WT and heterozygous mice measured by SMN-ECL.</p

SMN protein levels in SMA patient and control whole blood samples.

<p>(A) SMN levels with respect to age in all subjects. (B) SMN protein levels were measured in SMA patients with 2, 3 and 4 copies of <i>SMN2</i>. In patients over 2 months of age, SMN levels were significantly greater in SMA patient samples with 4 <i>SMN2</i> copies relative to those with 2 and 3 <i>SMN2</i> copies (p = 0.0001). (C) SMN was also measured in three control samples and SMN levels were found to be significantly greater in the control samples relative to levels in SMA patients over 2 months of age (p < 0.0001).</p

SMN protein was found in various cell types in whole blood.

<p>Platelets, red blood cells, PBMCs and reticulocytes were separated by a fractionation procedure.</p

SMN protein levels in WT and C/C-allele SMA mice of different ages.

<p>SMN protein levels were measured by SMN-ECL at various days post-birth in (A) brain, (B) whole blood, (C) spinal cord, and (D) gastrocnemius muscle.</p

SMN protein levels in capillary and venous blood obtained over time from healthy volunteers did not vary significantly.

<p>Venous (A, B) and capillary (C) whole blood samples were obtained at 0, 4, 6, 24, 48, 72 hours and 1, 2, 3, 4 weeks from five healthy individuals. Fig 2B is an expanded version of Fig 2A. (D) SMN protein levels in capillary blood correlated significantly with SMN levels in venous blood (r² = 0.76, p < 0.0001).</p