Enhance The Feasibility Of Transplantation Of Hematopoietic Stem / Progenitor Cells In The Homing Of Hematopoietic Reconstitution Capacity Strategy

Objective To explore the differences of homing potential among HS/PC originated from BM,mPB and UCB groups and to reveal whether iBMI strategy could promote the potential of engraftment,self-renewal, multilineage differentiation,secondary repopulation of UCB-CD34~+ cells in xenotransplanted NOD/SCID mouse model compared to the results obtained by intravenous method.Methods Aliquots containing 1×10~3, 1×10~4,0.5×10~5,1×10~5 and 5×10~5 CD34~+ cells originated from BM,mPB and UCB groups were transplanted into sublethally irradiated NOD/SCID mice via iVI and iBMI routes.The distribution of CFSE-labeled CD34~+ cells inside the recipients were observed in frozen sections of different organs or by flow cytometry,PCR as well as optical in vivo imaging.Furthermore,we investigated UCB-CD34~+ for the engraftment level,reconstitution of hematopoietic and immunological function,colony forming units and engratment of secondary transplantation.Results①The differences of homing efficiency among CD34~+ cells originated from BM,mPB and UCB groups were not statistically significant(P＞0.05).A wide variation from mice to mice can be noted.②We utilized the whole body optical imaging to visualize the HS/PC homing which showed that CFSE-labeled CD34~+ cells distributed dispersedly all around at the early stage of homing by iVI route and then cells accumulated at the bone marrow especially at the site of long and flat bones(eg:scapulae and pelvic bones) by 24 h after transplantation.While the cells injected into the bone marrow mainly migrated to immediate flat bones and then reached to other sites of bones 24h later.Till 72h cells lodged in the bone marrow with similar distribution in both routes.It is emphasized that lots of labeled cells were obviously sequestrated by other non hematopoietic organs like the lung and liver by iVI route and few was trapped by iBMI route.③The bone marrow homing efficiency of CD34~+ cells by iBMI was(12±3.91 %),about 10 times higher than that by iVI(1.5±0.15%).④Comparable 8-week-engraftment of human cells were observed in iVI and iBMI groups as of(44.063±20.095)%and(45.881±22.316)%respectively, when given transplants of 1×10~5 UCB-CD34~+ cells(P＞0.05).More superior 8-week-engraftment of human cells were observed in intra-bone marrow recipients as of(54.019±31.338)%than in intra-venous recipients as of(12.197±10.350)%when given transplants of 1.0×10~4 CD34~+ cells (P＜0.01).Human cell engraftment was observed in intra-bone marrow but not for intra-venous recipients when given transplants of 1.0×10~3 CD34~+ cells.⑤The multilinage differentiation profile showed the majority of human cells were CD19~+ B lymophocytes and early CD33~+ myeloid cells.At the 5-week the markers of each lineage were lower than that at 3-week or 8-week.While the engraftment in peripheral blood, spleen and bone marrow showed similar trends and iBMI showed predominance 8-week after transplantation.Conclusion Our study indicated that the differences of homing efficiency of CD34~+ cells originated from BM,mPB and UCB groups were not statistically significant.This study also confirmed that intra-bone marrow strategy efficiently increased the homing,engraftment and multi-hematopoietic reconstitution potential of UCB derived HS/PC in xenotransplanted NOD/SCID mouse model.