Abstract
We describe the relation between umbilical cord clamping time and two different enrichment system of CD34+ stem cells from umbilical cord blood with the proliferative ability and bone marrow reconstitution of the stem cells obtained. After an obstetrician performed the cord blood collection, the purification of stem cells was performed either with a combination of monoclonal antibodies (negative selections) using the Stem Sep method, or with a positive cells selection based on their surface CD34 antigens using the Mini Macs system. An excellent recovery of haematopoietic progenitors [Burst Forming Unit Erythroids (BFUE); Colony Forming Unit Granulocytes and Macrophages (CFU-GM); and Colony Forming Unit Granulocytes, Erythroids, Monocytes and Macrophages (CFU-GME)], inversely related to the increase in clamping time, was performed with the Mini Macs system (54% of colonies, with 90% purity). With Stem Sep method, haematopoietic progenitor's recovery was 35% (with 80% purity). By applying early clamping of umbilical cord blood we obtained a greater number of CD34+ cells and their clonogenic activity was increased with enrichment. This is a useful technique considering that the number of CD34+ stem cells usually contained from a unit of placental blood is enough for the transplant to a child, but not for an adult. Thus, using these methods, we can get a larger number of CD34+ stem cells which reduces the risk of Graft versus Host Disease also in adult patients, producing survival rates similar to those obtained with transplantation of bone marrow from unrelated donors.
Highlights
Haematopoietic cells are heterogeneous and belong to different lineages and are at different stages of maturity
Cord blood is an attractive alternative to bone marrow or to peripheral blood cells mobilised by growth factors as a source of transplantable haematopoietic tissue.[16,17]
Using the magnetic cell sorting Mini Macs or Stem Sep system to isolate CD34+ cells we demonstrated an excellent recovery of haematopoietic progenitors and haematopoietic colony forming cells when an umbilical cord blood cut was made early
Summary
Haematopoietic cells are heterogeneous and belong to different lineages and are at different stages of maturity. The structural and functional integrity of the haematopoietic system is maintained by CD34+ stem cells (Figure 1), which can self-renew, producing other stem cells or differentiate and produce a various haematopoietic lineages.[1] Haematopoietic progenitor stem cell transplantation is an important therapy for certain haematological and malignant disorders.[2,3,4,5] Umbilical cord blood, called placental blood, contains a high number of haematopoietic progenitor cells, which are known to possess significant potential for clinical application, and show a high proliferative capacity.[6]. These factors are important for the risk of relapse and mortality.[9]
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