title: Natural killer cells stimulated with PM21 particles expand and biodistribute in vivo: Clinical implications for cancer treatment.
abstract: OBJECTIVE
  Natural killer (NK) cell immunotherapy for treatment of cancer is promising, but requires methods that expand cytotoxic NK cells that persist in circulation and home to disease site.
  
  
  METHODS
  We developed a particle-based method that is simple, effective and specifically expands cytotoxic NK cells from peripheral blood mononuclear cells (PBMCs) both ex vivo and in vivo. This method uses particles prepared from plasma membranes of K562-mb21-41BBL cells, expressing 41BBL and membrane bound interleukin-21 (PM21 particles).
  
  
  RESULTS
  Ex vivo, PM21 particles caused specific NK-cell expansion from PBMCs from healthy donors (mean 825-fold, range 163-2216, n = 13 in 14 days) and acute myeloid leukemia patients. The PM21 particles also stimulated in vivo NK cell expansion in NSG mice. Ex vivo pre-activation of PBMCs with PM21 particles (PM21-PBMC) before intraperitoneal (i.p.) injection resulted in 66-fold higher amounts of hNK cells in peripheral blood (PB) of mice compared with unactivated PBMCs on day 12 after injection. In vivo administration of PM21 particles resulted in a dose-dependent increase of PB hNK cells in mice injected i.p. with 2.0 × 10(6) PM21-PBMCs (11% NK cells). Optimal dose of 800 µg/injection of PM21 particles (twice weekly) with low-dose interleukin 2 (1000 U/thrice weekly) resulted in 470 ± 40 hNK/µL and 95 ± 2% of total hCD45(+) cells by day 12 in PB. Furthermore, hNK cells were found in marrow, spleen, lung, liver and brain (day 16 after i.p. PM21/PBMC injection), and mice injected with PM21 particles had higher amounts.
  
  
  CONCLUSIONS
  The extent of NK cells observed in PB, their persistence and the biodistribution would be relevant for cancer treatment.
authors.affiliation: Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, USA.
authors.forename: Jeremiah L
authors.initials: JL
authors.lastname: Oyer
authors.affiliation: Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, USA.
authors.forename: Veethika
authors.initials: V
authors.lastname: Pandey
authors.affiliation: Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, USA.
authors.forename: Robert Y
authors.initials: RY
authors.lastname: Igarashi
authors.affiliation: Division of Pediatrics and Cell Therapy Section, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
authors.forename: Srinivas S
authors.initials: SS
authors.lastname: Somanchi
authors.affiliation: Florida Hospital Cancer Institute, Orlando, Florida, USA.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Zakari
authors.affiliation: Florida Hospital Cancer Institute, Orlando, Florida, USA.
authors.forename: Melhem
authors.initials: M
authors.lastname: Solh
authors.affiliation: Division of Pediatrics and Cell Therapy Section, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
authors.forename: Dean A
authors.initials: DA
authors.lastname: Lee
authors.affiliation: Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, USA.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Altomare
authors.affiliation: Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, USA. Electronic address: alicja.copik@ucf.edu.
authors.forename: Alicja J
authors.initials: AJ
authors.lastname: Copik
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002462:Cell Membrane; D049109:Cell Proliferation / Q000187:drug effects*; D005260:Female; D006801:Humans; D007167:Immunotherapy / Q000379:methods; D007376:Interleukin-2 / Q000494:pharmacology*; D007378:Interleukins / Q000494:pharmacology*; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology*; D015470:Leukemia, Myeloid, Acute / Q000628:therapy*; D007963:Leukocytes, Mononuclear / Q000166:cytology; D008213:Lymphocyte Activation / Q000276:immunology*; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D000098546:Interleukin-21
chemical_list: D007376:Interleukin-2; D007378:Interleukins; D000098546:Interleukin-21
keywords: NK cells; in vivo NK cell expansion; membrane bound IL-21; membrane particles