Platelet characteristic antigens of CD34+ cells in cryopreserved cord blood: a study of platelet-derived microparticles in transplant processing.
OBJECTIVE
In previous studies, we found that platelet microparticles (PMPs) bind to cord blood (CB) CD34+ cells and transfer adhesion molecules to them, which enhances their engraftment. Before applying this phenomenon in actual transplants, we investigated the effect of PMPs on cryopreserved CD34+ cells in CB.


METHODS
We cryopreserved 18 CB units, then evaluated the binding of PMPs to CD34+ cells after thawing, by varying the expression of platelet characteristic antigens (CD41a, CD61, CD62P and CXCR4) on these cells. Adherence of the CD34+ cells, coated with freeze/thaw-induced PMPs, to endothelium and fibronectin was also studied, as were the effects of thrombin-induced PMPs from both fresh and preserved CB platelets.


RESULTS
PMPs induced by freezing and thawing adhered less well to CD34+ cells than did those from fresh CB, and cells coated with these PMPs had poor adherence. However, thrombin-induced PMPs from both fresh and preserved CB platelets bound equally well to cryopreserved CD34+ cells and improved their adhesion properties.


CONCLUSIONS
PMPs could be a useful tool for enhancing engraftment after CB transplantation.
Liu
B
B
Medical Experimental Centre, Guangzhou 12th People's Hospital, Guangzhou, China. binliu7@hotmail.com
Chen
J S
JS
Cao
M
M
Gu
S L
SL
Liao
C
C
Li
D Z
DZ
Zhong
H Z
HZ
D017304:Annexin A5 / Q000502:physiology; D018952:Antigens, CD34 / Q000032:analysis*; D001792:Blood Platelets / Q000737:chemistry*; D002452:Cell Count; D018925:Chemokines / Q000032:analysis; D015925:Cryopreservation; D004730:Endothelium, Vascular / Q000502:physiology; D005312:Fetal Blood / Q000166:cytology* / Q000637:transplantation*; D005353:Fibronectins / Q000502:physiology; D006085:Graft Survival / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D039661:Integrin beta3 / Q000032:analysis; D019007:P-Selectin / Q000032:analysis; D015539:Platelet Activation / Q000502:physiology; D010973:Platelet Adhesiveness / Q000502:physiology*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000032:analysis; D013917:Thrombin / Q000502:physiology
D017304:Annexin A5; D018952:Antigens, CD34; D018925:Chemokines; D005353:Fibronectins; D039661:Integrin beta3; D019007:P-Selectin; D019038:Platelet Glycoprotein GPIb-IX Complex; D013917:Thrombin