title: Effects of amifostine on clonogenic mesenchymal progenitors and hematopoietic progenitors exposed to radiation.
abstract: OBJECTIVE
  To determine the radiation sensitivities of mesenchymal progenitors and hematopoietic progenitors, and to determine the in vitro effects of amifostine on hematopoietic and mesenchymal progenitors exposed to radiation.
  
  
  METHODS
  Radiosensitivity of mesenchymal progenitor cells was determined by exposing marrow low-density cells to radiation at doses of 100 to 800 cGy. Mesenchymal cell colonies were established by plating 2.5 x 10(5) marrow low-density cells in long-term marrow culture medium (LTCM). The size, frequency, and cellular composition of the mesenchymal progenitor cells were scored after 14 days of incubation. Mesenchymal progenitor cells were subdivided into progenitors forming fibroblast and adipocyte mixed colonies (CFU-FA), and pure fibroblast colonies (CFU-F). Hematopoietic progenitors were assessed by methylcellulose-based assay.
  
  
  RESULTS
  Radiation at 100 cGy caused a mild decrease in CFU-F and CFU-FA derived colonies by 12% and 13%, respectively; 200 cGy decreased CFU-F by 36% and CFU-FA by 52%; 400 cGy decreased CFU-F by 50% and CFU-FA by 86%; and 600 cGy decreased CFU-F by 24%, with total absence of CFU-FA. Pretreatment with amifostine protected 100% of CFU-F at 100 and 200 cGy, 84% at 400 cGy, 46% at 600 cGy, and 14% at 800 cGy. With CFU-FA colonies amifostine pretreatment provided only minimal radioprotection. For hematopoietic progenitors radiation at 100 cGy reduced CFU-GM by 74% but had no significant effect on CFU-GEMM and BFU-E. Radiation at 200 cGy decreased CFU-GEMM by 72%, BFU-E by 54%, and CFU-GM by 84%; 400 cGy further decreased CFU-GEMM by 83%, BFU-E by 81%, and CFU-GM by 93%. Pretreatment with amifostine resulted in twofold stimulation of CFU-GEMM and BFU-E colonies. All BFU-E colonies were protected up to 200 cGy. For CFU-GEMM amifostine pretreatment resulting in 68% at 200 cGy and 31% at 400 cGy. For CFU-GM colonies it was 54% at 100 cGy, 32% at 200 cGy, and 12% at 400 cGy.
  
  
  CONCLUSIONS
  Mesenchymal progenitor cell subpopulations are differentially sensitive to radiation. Amifostine protects both mesenchymal and hematopoietic progenitors against radiation injury, though the level of protection appears to be dependent upon the sensitivities of these progenitor cells to radiation. Amifostine is a potent stimulant of BFU-E and CFU-GEMM progenitor colonies.
authors.affiliation: Department of Pediatric Hematology/Oncology, Louisiana State University Health Science Center, New Orleans, LA, USA. jramdas@geisinger.edu
authors.forename: Jagadeesh
authors.initials: J
authors.lastname: Ramdas
authors.forename: Rajashekharan P
authors.initials: RP
authors.lastname: Warrier
authors.forename: Charles
authors.initials: C
authors.lastname: Scher
authors.forename: Vincent
authors.initials: V
authors.lastname: Larussa
mesh_terms: D017667:Adipocytes / Q000166:cytology; D004999:Amifostine / Q000494:pharmacology*; D002478:Cells, Cultured / Q000187:drug effects / Q000528:radiation effects; D003114:Colony-Forming Units Assay; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000166:cytology; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000528:radiation effects; D006801:Humans; D066298:In Vitro Techniques; D008648:Mesoderm / Q000187:drug effects / Q000528:radiation effects; D011836:Radiation Tolerance; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D013234:Stem Cells / Q000187:drug effects* / Q000528:radiation effects
chemical_list: D011837:Radiation-Protective Agents; D004999:Amifostine