| Objective The purpose of this study was to examine the percentage and the functional competence (proliferative capacity, cell cycle dynamics and apoptosis) of CD34+ HSC/HPCs in RA.Methods Frequencies of peripheral blood CD34+ HSC/HPCs from RA patients and healthy controls matched for age, sex, and ethnicity were measured by flow cytometry. Proliferative capacity in purified CD34+ HPCs after stimulation with early hematopoietins (IL-6 20ng/ml, IL-3 20ng/ml ,SCF 100ng/ml, Flt-3L 100ng/ml) were assessed by carboxyfluorescein diacetate succinimidyl ester (CFSE) staining.Cycle dynamics in the fresh purified CD34 HPCs and after stimulation with early hematopoietins were measured by Propidium iodide (PI) staining and flow cytometry. And the apoptosis of HSC/HPC were detected by Annexin V/FITC and PI staining and flow cytometr The relationships between HSC/HPCs functions,frequencies and disease duration, activity, severity and treatment were analyzed.Result(1)The frequencies of CD34+ HSC/HPCs in lymphoid cells in RA patients was significantly lower than in healthy donors [(0.38±0.21)% vs(0.13±0.09)%,P<0.05], the frequencies of CD34 +HSC/HPCs in RA were positively correlation with RBC and Hb ( r=0.467, r=0.487 respectively , p=0.044, p=0.025 respectively),and negitively correlation with CRP(r=-0.585, p=0.028).(2)CD34 MFI were higher in RA patients than those in the normal controls(56.87±33.4 vs 31.19±10.8 ,P<0.05),the MFI of RA paitients was positively correlated healthy assessment questionaire (HAQ) and X rays stages ,but reversely correlated with the number of platelat.(3) For the cell cycle status of fresh purified CD34+ HSC/HPCs,there is a smaller percentage derived from rheumatoid arthritis patients CD34+cells were in (S+G2/M) stage of cell cycly than these from normal [(13.63±4.692)% vs (14.00±6.838)%,P=0.019].And it were independent of other clincal feature such as disease duration, disease activity, and were present to the same degree in treated patients.(4) RA-derived HSC/HPCs completed only 4 generations in contrast with that control HSC/HPCs passed through 9 replication cycles over 4 days after growth factor(IL-6 20ng/ml, IL-3 20ng/ml ,SCF 100ng/ml, Flt-3L 100ng/ml) stimulation in stem cell medium, (4.63±0.352 vs 8.50±0.847,P=0.001). And the replication cycles of CD34+ HSC/HPCs in RA were posively correlation with the percentage of lymph cell (r=0.648 , p=0.023) , negitively correlation with WBC, percentage of neutrophilic leukocyte .(r=-0.779,-0.660, respectively, p=0.003, 0.019 , respectively)(5) The apoptosis of CD34+cells in RA patients is higher than normal CD34+cells[(46.42±2.540)%vs(17.54±2.009)%,P=0.000]. The death of CD34+cells in RA patients is higher than normal CD34+cells[(14.81±2.045)%vs(5.86±1.102)%,P=0.000].And the percentage of apoptosis of CD34+cells in RA patients was correlation with the WBC.Conclusion Circulating HSC/HPCs in RA maybe were diminished. HSC/HPCs from RA patients displayed growth factor nonresponsiveness and sluggish cell cycle progression. Defective HPC function independent of disease activity markers suggests bone marrow failure as a potential pathogenic factor in RA.
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