The Significance Of Quantitative Detection Of Microchimerism For Hematopoietic Stem Cell Transplantation

Objection By quantitatively detecting microchimerism and analyzing dynamic changes,the early engraftment of allogeneic hematopoietic stem cell transplantation(allo-HSCT)and the risk of relapse at early stage of patients can be observed early,so that appropriate intervention can be performed for treatment,to achieve the purpose of reducing the failure rate of transplantation.The similarities and differences of engraftment between cord blood transplantation(CBT)and peripheral blood stem cell transplantation(PBSCT)were compared.Methods A total of 15 consecutive patients underwent allo-HSCT.The median age was 16 years(0.8-60 years),and the median weight was 42 kg(8-80 kg(recipient weight)).There were 5 cases of acute leukemia(AL),2 cases of myelodysplastic syndrome(MDS),5 cases of aplastic anemia(AA),2 cases of severe ? thalassemia,and 1 case of WiskotAldrich syndrome(WAS).In 5 cases of PBSCT,the median infused nucleated cell dose and CD34+ dose were 85.60 x 10^7/kg(range 69.90-109.90 x 10^7/kg)and 39.80 x 10^5/kg(range 30.70-49.40 x 10^5/kg).In 10 cases of CBT,the median infused nucleated cell dose and CD34+ dose were 8.91 x 10^7/kg(range 3.84-11.00 x 10^7/kg)and 2.50 x 10^5/kg(range 1.34-4.57 x 10^5/kg).Peripheral blood samples from patients after transplantation were collected at least 15 days and microchimerism was quantified using insertion or deletion polymorphism based on real-time quantitative polymerase chain reaction(Indel-q PCR).Results Of the 15 patients,15 received neutrophil engraftment and 11 patients received platelet engraftment with a median time of 16 and 22 days.Thirteen patients achieved complete donor chimerism(CDC)with a median time of 17 days.Of the 10 patients who reached CDC without increasing mixed chimerism(IMC),9 were fully engraftment,1 neutrophil engraftment and platelet was not engraftment.In 3 patients with one IMC,all patients neutrophil were successfully engraftment and 2 platelet was engraftment.In 2 patients who had multiple IMCs and never reached CDC,2 platelets were not engraftment.One patient with multiple IMCs relapsed.Of the 11 evaluable patients,3 had grade II-IV graft-versus-host disease(GVHD).Among the patients who survived for more than 100 days,no patients developed chronic GVHD.To date,13 of 15 patients have survived with a median survival of 4.7 months(0.9-11.0 months).The overall survival rate(OS)was 86.7%.Conclusion 1.Indel-q PCR technology is an effective method for detecting microchimerism,can be used as an effective predictor of engraftment and the risk of relapse.2.By comparing the engraftment of CBT and PBSCT,although platelet engraftment of PBSCT group is superior to CBT,there is no significant difference about neutrophil engraftment and overall survival,indicating that CBT is an effective treatment for malignant and non-malignant refractory hematological diseases.