Isolation and characterisation of human gingival margin-derived STRO-1/MACS+ and MACS− cell populations
Authors: Karim M Fawzy El-Sayed, Sebastian Paris, Christian Graetz, Neemat Kassem, Mohamed Mekhemar, Hendrick Ungefroren, Fred Fändrich, Christof Dörfer
Journal: International Journal of Oral Science (2014)

Recently, gingival margin-derived stem/progenitor cells isolated via STRO-1/magnetic activated cell sorting (MACS) showed remarkable periodontal regenerative potential in vivo. As a second-stage investigation, the present study's aim was to perform in vitro characterisation and comparison of the stem/progenitor cell characteristics of sorted STRO-1-positive (MACS+) and STRO-1-negative (MACS−) cell populations from the human free gingival margin. Cells were isolated from the free gingiva using a minimally invasive technique and were magnetically sorted using anti-STRO-1 antibodies. Subsequently, the MACS+ and MACS− cell fractions were characterized by flow cytometry for expression of CD14, CD34, CD45, CD73, CD90, CD105, CD146/MUC18 and STRO-1. Colony-forming unit (CFU) and multilineage differentiation potential were assayed for both cell fractions. Mineralisation marker expression was examined using real-time polymerase chain reaction (PCR). MACS+ and MACS− cell fractions showed plastic adherence. MACS+ cells, in contrast to MACS− cells, showed all of the predefined mesenchymal stem/progenitor cell characteristics and a significantly higher number of CFUs (P<0.01). More than 95% of MACS+ cells expressed CD105, CD90 and CD73; lacked the haematopoietic markers CD45, CD34 and CD14, and expressed STRO-1 and CD146/MUC18. MACS− cells showed a different surface marker expression profile, with almost no expression of CD14 or STRO-1, and more than 95% of these cells expressed CD73, CD90 and CD146/MUC18, as well as the haematopoietic markers CD34 and CD45 and CD105. MACS+ cells could be differentiated along osteoblastic, adipocytic and chondroblastic lineages. In contrast, MACS− cells demonstrated slight osteogenic potential. Unstimulated MACS+ cells showed significantly higher expression of collagen I (P<0.05) and collagen III (P<0.01), whereas MACS− cells demonstrated higher expression of osteonectin (P<0.05; Mann–Whitney). The present study is the first to compare gingival MACS+ and MACS− cell populations demonstrating that MACS+ cells, in contrast to MACS− cells, harbour stem/progenitor cell characteristics. This study also validates the effectiveness of the STRO-1/MACS+ technique for the isolation of gingival stem/progenitor cells. Human free gingival margin-derived STRO-1/MACS+ cells are a unique renewable source of multipotent stem/progenitor cells. Researchers in Germany and Egypt have identified a cell population in the gum margins with regenerative potential. A team led by Karim Fawzy El-Sayed, from the Christian Albrechts University in Kiel, Germany, and Cairo University in Egypt, magnetically sorted human gum tissue using antibodies that bind STRO-1, a surface protein that marks cells as mesenchymal stem cells. Cells expressing STRO-1 showed more molecular characteristics of stem cells, had greater proliferative capacity and could differentiate into more cell types than cells without STRO-1 on their surface. The study is the first to directly compare the two gum cell populations. STRO-1-positive cells in the gum margin could provide a renewable source of multipotent stem cells for the treatment of gingivitis and other types of periodontal disease.