title: Granulocyte colony-stimulating factor (G-CSF) promotes spermatogenic regeneration from surviving spermatogonia after high-dose alkylating chemotherapy.
abstract: BACKGROUND
  The lifesaving chemotherapy and radiation treatments that allow patients to survive cancer can also result in a lifetime of side-effects, including male infertility. Infertility in male cancer survivors is thought to primarily result from killing of the spermatogonial stem cells (SSCs) responsible for producing spermatozoa since SSCs turn over slowly and are thereby sensitive to antineoplastic therapies. We previously demonstrated that the cytokine granulocyte colony-stimulating factor (G-CSF) can preserve spermatogenesis after alkylating chemotherapy (busulfan).
  
  
  METHODS
  Male mice were treated with G-CSF or controls before and/or after sterilizing busulfan treatment and evaluated immediately or 10-19 weeks later for effects on spermatogenesis.
  
  
  RESULTS
  We demonstrated that the protective effect of G-CSF on spermatogenesis was stable for at least 19 weeks after chemotherapy, nearly twice as long as previously shown. Further, G-CSF treatment enhanced spermatogenic measures 10 weeks after treatment in the absence of a cytotoxic insult, suggesting G-CSF acts as a mitogen in steady-state spermatogenesis. In agreement with this conclusion, G-CSF treatment for 3 days before busulfan treatment exacerbated the loss of spermatogenesis observed with G-CSF alone. Reciprocally, spermatogenic recovery was modestly enhanced in mice treated with G-CSF for 4 days after busulfan. These results suggested that G-CSF promoted spermatogonial proliferation, leading to enhanced spermatogenic regeneration from surviving SSCs. Similarly, there was a significant increase in proportion of PLZF+ undifferentiated spermatogonia that were Ki67+ (proliferating) 1 day after G-CSF treatment.
  
  
  CONCLUSIONS
  Together, these results clarify that G-CSF protects spermatogenesis after alkylating chemotherapy by stimulating proliferation of surviving spermatogonia, and indicate it may be useful as a retrospective fertility-restoring treatment.
authors.affiliation: Department of Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA.
authors.forename: Travis
authors.initials: T
authors.lastname: Kotzur
authors.affiliation: Department of Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA.
authors.forename: Roberto
authors.initials: R
authors.lastname: Benavides-Garcia
authors.affiliation: Department of Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Mecklenburg
authors.affiliation: Department of Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA.
authors.forename: Jamila R
authors.initials: JR
authors.lastname: Sanchez
authors.affiliation: Departments of Biomedical Engineering and Ophthalmology, The Ohio State University, 1080 Carmack Road, Columbus, OH, 43210, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Reilly
authors.affiliation: Department of Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA. brian.hermann@utsa.edu.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Hermann
mesh_terms: D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000633:toxicity; D002066:Busulfan / Q000633:toxicity*; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005455:Fluorescent Antibody Technique; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D000075722:Promyelocytic Leukemia Zinc Finger Protein; D020011:Protective Agents / Q000494:pharmacology; D012038:Regeneration / Q000187:drug effects; D013091:Spermatogenesis / Q000187:drug effects* / Q000502:physiology; D013093:Spermatogonia / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D013737:Testis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D018906:Antineoplastic Agents, Alkylating; D019394:Ki-67 Antigen; D051741:Kruppel-Like Transcription Factors; D000075722:Promyelocytic Leukemia Zinc Finger Protein; D020011:Protective Agents; C513267:Zbtb16 protein, mouse; D016179:Granulocyte Colony-Stimulating Factor; D002066:Busulfan
keywords: Adjuvant; Cancer; Fertility preservation; Infertility; Late effects; Spermatogonial stem cells