TEM/EDX Observation of Micro-beads of Magnetically Activated Cell Sorting (MACS) System and Separation Trial of Mouse Mesenchymal Stem Cells from Bone Marrow Cells by MACS System

Abstract

Magnetically activated cell sorting (MACS) system is one isolation technique of mesenchymal stem cells (MSC) from bone marrow cells. TEM/EDX observation revealed that its micro-beads had the size of about 0.5 to 1.0 µm and consisted of matrix and inorganic phases. The inorganic phase contained small particles of about 40 nm size, and consisted of Fe, Si, O, Cl (e.g., Fe₃O₄ + SiO₂ + FeCl₃). In MACS system, lineage (hematopoietic) cell depletion kit reduced the cell number of bone marrow cells to 1.2 %. Subsequent positive selection by CD117, anti-Sca-1, CD34 and CD44 micro-beads lead to the cell collection rates of 0.57 %, 0.10 %, 0.13 % and 0.14 %, respectively. A combination of three micro-beads for lineage cell depletion kit, CD117 and anti-Sca-1 micro-beads succeeded in reducing the cell collection rate down to 0.04 %, matching a normal existing rate of MSC in bone marrow cells (0.01 to 0.10 %).