title: Physiological testosterone levels enhance chondrogenic extracellular matrix synthesis by male intervertebral disc cells in vitro, but not by mesenchymal stem cells.
abstract: BACKGROUND
  Testosterone (T) is a hormone and regulator involved in the processes of development of the organism (ie, promoting development of bone and muscle mass). Although T effects on the mesenchyme-derived muscle, bone, and adipose tissues are well studied, T effects on intervertebral disc (IVD) have not been reported.
  
  
  OBJECTIVE
  The aim was to test the following hypothesis: if a physiological concentration of T (∼30 nM) can improve in vitro chondrogenesis of human IVD cells and mesenchymal stem cells (MSCs).
  
  
  METHODS
  Human IVD cells and MSCs were differentiated to chondrogenic lineage on gelatin scaffolds for 4 weeks, in the presence or absence of T.
  
  
  METHODS
  Chondrogenesis was assessed by cell viability, by measuring gene expression with quantitative polymerase chain reaction and extracellular matrix (ECM) accumulation with immunoblotting, immunohistochemical, and biochemical methods.
  
  
  RESULTS
  Supplementation of T to chondrogenic culture did not affect viability. In male IVD cells, T had a beneficial impact on chondrogenesis, particularly in nucleus pulposus cells, demonstrated by an increased expression of aggrecan, collagen type I, and especially collagen type II. Conversely, T had no effects on chondrogenesis of female IVD cells or MSCs from both genders. A gene expression array of transforming growth factor β/bone morphogenetic protein signaling cascade showed that in male IVD cells, T promoted a stable general but nonsignificant increase in gene expression. Furthermore, aromatase inhibitor anastrazole repressed the effect of T on ECM expression by IVD cells. The results suggest that T increased ECM accumulation in male IVD cells in combination with its conversion to estradiol by the enzyme aromatase.
  
  
  CONCLUSIONS
  We demonstrated that T effectively enhances in vitro chondrogenesis in male IVD cells, rising the interest in the possible role of sex hormones in IVD degeneration. Nevertheless, T does not affect chondrogenic differentiation of female IVD cells and MSCs from both genders.
authors.affiliation: Biomedical Laboratories, Swiss Paraplegic Research, G.A. Zaech Strasse 4, 6207 Nottwil, Switzerland.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bertolo
authors.affiliation: Cantonal Hospital of Lucerne, Spitalstrasse 16, 6000 Lucerne, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Baur
authors.affiliation: Swiss Paraplegic Centre, Zaechstrasse 1, 6207 Nottwil, Switzerland; School of Medicine, Griffith University, University Drive, 4131 Meadowbrook Qld, Brisbane, Queensland, Australia.
authors.forename: Niklaus
authors.initials: N
authors.lastname: Aebli
authors.affiliation: Institute for Biomechanics, Schafmattstrasse 30, 8093 ETH Zurich, Switzerland.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Ferguson
authors.affiliation: Biomedical Laboratories, Swiss Paraplegic Research, G.A. Zaech Strasse 4, 6207 Nottwil, Switzerland; Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014 Bern, Switzerland. Electronic address: jivko.stoyanov@paraplegie.ch.
authors.forename: Jivko
authors.initials: J
authors.lastname: Stoyanov
mesh_terms: D000328:Adult; D053674:Aggrecans / Q000378:metabolism; D000077384:Anastrozole; D047072:Aromatase Inhibitors / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D020219:Chondrogenesis / Q000187:drug effects / Q000502:physiology*; D024043:Collagen Type II / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008875:Middle Aged; D009570:Nitriles / Q000494:pharmacology; D012737:Sex Factors; D013739:Testosterone / Q000494:pharmacology / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology
chemical_list: D053674:Aggrecans; D047072:Aromatase Inhibitors; D024043:Collagen Type II; D009570:Nitriles; D016212:Transforming Growth Factor beta; D014230:Triazoles; D000077384:Anastrozole; D013739:Testosterone
keywords: Aromatase; Chondrogenesis; Intervertebral disc cells; Mesenchymal stem cells; Sex hormones; Testosterone and three-dimensional cultures