Abstract: Objective In this report, the absolute SMPCs count was performed by two single-platform technologies. The reliability of two methods, including intra- and inter-observer variability, was assessed using the intra-class correlation coefficient (ICC), respectively. The stability of SMPCs numbers in blood samples was analyzed. Methods The blood samples were obtained from Institute of Cancer Research (ICR) mice. The samples were processed through now lyse/one-wash procedure and c-kit-/CD140b+/lineage-/sca-1+ SMPCs were analyzed by exclusion of dead cells and by fluorescence-minus-one control. SMPCs were enumerated by two methods: 1) bead-based 123count eBeads? (eBioscience) Count; 2) ‘direct volume’-based Accuri C6 Flow Cytometer? (BD) Count. The cells were measured immediately and after storage of blood samples for 24 h and 48 h, respectively. The SCI in mice were induced by Allen’s device and the number of SMPCs was detected 24h after SCI. Results There are good intra-observer and inter-observer agreement in both methods. It was demonstrated SMPCs are unstable in blood samples. The number of SMPCs increased after 24h in spinal cord injury (SCI) mice. Conclusions Two reproducible protocols for SMPCs quantification were established. Acute spinal cord injury increases the smooth muscle progenitor cells in mice. These protocols should facilitate future studies to further define the role of SMPCs as cellular biomarkers in SCI.

Key words: spinal cord injury, absolute count, smooth muscle progenitor cells, Flow cytometry, single-platform