Constitution and telomere dynamics of bone marrow stromal cells in patients undergoing allogeneic bone marrow transplantation

We evaluated the genotypic origin of mesenchymal stem cells (MSC) following sex-mismatched allogeneic bone marrow transplantation (BMT), and investigated the telomere dynamics in MSC in normal individuals and patients after BMT. The study population consisted of 11 patients with hematologic disorders who showed complete chimerism after BMT. Telomere length was measured in MSC using Southern blotting analysis in eight patients and 18 healthy subjects as a control group. Following culture, MSC were identified by the expression of SH2 and SH4, and lack of CD14, CD34, and CD45. All MSC showed the recipient genotype, based on the results of fluorescent in situ hybridization analysis using X-chromosome satellite probes or microsatellite DNA polymorphism analysis. The mean telomere length in MSC from normal controls was 7.2+/-0.53 kb (range, 6.12-7.78), and progressive telomere shortening was seen with age. There was no significant difference in MSC telomere length between the BMT group and age-matched controls. This study confirmed that the MSC isolated from the recipients of allogeneic BMT did not have the donor genotype, despite complete chimerism. Moreover, MSC were demonstrated to show progressive loss of telomere length with age, but the telomeres in MSC were not affected by BMT.