PTPRC and myelodysplastic syndrome: The frequencies of engraftment, determined by a threshold of 0.5% human CD45+ cells in the BM, was also significantly lower at 0.06 ± 0.02 for HR-MDS-MSC groups (n = 8 mice, Fig. 5d), compared to full engraftment in healthy MSC groups (n = 12 mice).