title: CD34(+)-selected stem cell boost for delayed or insufficient engraftment after allogeneic stem cell transplantation.
abstract: BACKGROUND
  Poor graft function without rejection may occur after stem cell transplantation (SCT). CD34(+) stem cell boost (SCB) can restore marrow function but may induce or exacerbate GvHD. We therefore investigated the feasibility and efficacy of CD34(+)-selected SCB in some patients with poor graft function. We present the results for eight patients (median age 46 years) transplanted initially for myelofibrosis, acute leukemia, myeloma and NHL. Six patients had received HLA-matched and two mismatched grafts (PB, BM; n=5, 3). After a median of 128 days post-transplant, the median leukocyte and platelet counts were, respectively, 2.05/nL and 18/nL. None had achieved platelet counts >50/nL even though donor chimerism was >95% in seven recipients.
  
  
  METHODS
  Positive selection of CD34(+) stem cells was performed on a CliniMACS device, observing GMP and achieving a median of 98.5% purity. The patients received a median of 1.7 x 10(6)/kg CD34(+) cells and 2.5 x 10(3)/kg CD3(+) T lymphocytes.
  
  
  RESULTS
  Hemograms at days +30, +60 and +90, respectively, showed steadily increasing median leukocyte (2.55, 3.15 and 4.20/nL) and platelet (29, 39 and 95/nL) counts. After a median follow-up of 144 days, five patients remained alive. No patient had developed acute or chronic GvHD. One patient died of leukemic relapse and two others of systemic mycosis.
  
  
  CONCLUSIONS
  These preliminary results point to the possibility of safely improving graft function using CD34(+) positively selected stem cells without necessarily increasing the incidence of GvHD in patients with poor graft function post-SCT. Experience with more patients and longer follow-up should clarify the optimal role for this procedure.
authors.affiliation: Department of BM Transplantation, University Hospital Hamburg, University of Hamburg, Hamburg, Germany.
authors.forename: Aa
authors.initials: A
authors.lastname: Oyekunle
authors.forename: U
authors.initials: U
authors.lastname: Koehl
authors.forename: H
authors.initials: H
authors.lastname: Schieder
authors.forename: F
authors.initials: F
authors.lastname: Ayuk
authors.forename: H
authors.initials: H
authors.lastname: Renges
authors.forename: N
authors.initials: N
authors.lastname: Fehse
authors.forename: T
authors.initials: T
authors.lastname: Zabelina
authors.forename: B
authors.initials: B
authors.lastname: Fehse
authors.forename: T
authors.initials: T
authors.lastname: Klingebiel
authors.forename: A
authors.initials: A
authors.lastname: Sputtek
authors.forename: Ar
authors.initials: A
authors.lastname: Zander
authors.forename: N
authors.initials: N
authors.lastname: Kröger
mesh_terms: D000293:Adolescent; D000328:Adult; D018952:Antigens, CD34 / Q000378:metabolism*; D005260:Female; D006086:Graft vs Host Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology / Q000276:immunology* / Q000502:physiology*; D014184:Transplantation, Homologous
chemical_list: D018952:Antigens, CD34