title: Iron availability is increased in individual human ovarian follicles in close proximity to an endometrioma compared with distal ones.
abstract: OBJECTIVE
  Does the iron content of an endometrioma represent a potential source of toxicity for the adjacent follicles?
  
  
  CONCLUSIONS
  The presence of an endometrioma increases iron and H/L ferritin levels, and transferrin receptor (TfR1) mRNA in individual follicles proximal to the endometrioma and is accompanied by reduced oocyte retrieval.
  
  
  BACKGROUND
  Levels of free iron in endometriotic ovarian cysts are much higher than those in normal serum or in non-endometriotic ovarian cysts. The presence of an endometrioma exerts a detrimental effect on the surrounding healthy ovarian tissue as reflected by a reduced number of developing follicles and oocytes retrieved in IVF cycles.
  
  
  METHODS
  This is a research study with prospective collection and evaluation of individual follicles (follicular fluid and luteinized granulosa cells) from the affected and the healthy ovaries of 13 women with unilateral endometrioma.
  
  
  METHODS
  Individual follicular samples (145) were obtained from 13 women with endometriosis-related infertility undergoing IVF-ICSI procedures from May 2012 to March 2013. All women had unilateral endometrioma not previously treated with surgery; the contralateral ovary was free of endometriomas and previous surgery. The average ± SEM age was 35.36 ± 2.5 years with anti-Mullerian hormone levels of 2.03 ± 0.55 ng/ml. Follicles were classified as: (i) proximal follicles, in physical contact with the endometrioma; (ii) distal follicles, present in the affected ovary but not in close contact with the endometrioma and (iii) contralateral follicles, in the contralateral healthy ovary. Iron content was measured by the FerroZine method. H/L ferritin subunits were evaluated by specific enzyme-linked immunosorbant assays. Expression of H ferritin and TfR1 was examined by semi-quantitative RT-PCR. Oocyte retrieval rates and Day 3 embryo quality were analyzed.
  
  
  RESULTS
  Total iron levels were higher in endometrioma-proximal follicles compared with endometrioma-distal ones (P = 0.009) and to follicles in the healthy ovary (P = 0.02). L ferritin was higher in proximal versus distal follicles (P = 0.044) or follicles from the healthy ovary (P = 0.027). H ferritin was higher in the proximal and distal follicles compared with follicles in the healthy ovary (P = 0.042 and P = 0.0067, respectively). H ferritin transcript levels in granulosa cells were higher in proximal follicles versus follicles from healthy ovary (P = 0.02). TfR1 transcript levels were higher in proximal versus distal follicles (P = 0.03) and versus follicles from the healthy ovary (P = 0.04). The oocyte retrieval rate was lower in proximal and distal follicles than in follicles from the healthy ovary (P = 0.001 and P = 0.04, respectively).
  
  
  CONCLUSIONS
  This is a study on a relatively small sample size and confirmation in a larger group of patients may be required. The method used to purify luteinized granulosa cells offers the best combination of purity, viability and total number of cells recovered. However, a minor contamination by CD45(+) cells (<5%) cannot be excluded.
  
  
  CONCLUSIONS
  This study represents a further in-depth analysis of the toxic influence of the endometrioma content on the surrounding follicles. We demonstrate the presence of iron-related compounds that are potentially toxic to developing ovarian follicles adjacent to the endometrioma during IVF. Our findings provide novel information that suggests that when surgical removal of the endometrioma is not the option, follicle aspiration at sites distant from the endometrioma might increase the probability of retrieving oocytes.
  
  
  BACKGROUND
  This project was supported by Fondazione Giorgio Pardi, Milan, Italy. The authors have no competing financial interests in relation to the content of this research paper.
  
  
  BACKGROUND
  NA.
authors.affiliation: Reproductive Sciences Laboratory, Division of Genetics and Cell Biology, San Raffaele Scientific Institute.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Sanchez
authors.forename: Enrico
authors.initials: E
authors.lastname: Papaleo
authors.forename: Laura
authors.initials: L
authors.lastname: Corti
authors.forename: Paolo
authors.initials: P
authors.lastname: Santambrogio
authors.forename: Sonia
authors.initials: S
authors.lastname: Levi
authors.forename: Paola
authors.initials: P
authors.lastname: Viganò
authors.forename: Massimo
authors.initials: M
authors.lastname: Candiani
authors.forename: Paola
authors.initials: P
authors.lastname: Panina-Bordignon
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis; D004715:Endometriosis / Q000601:surgery; D005260:Female; D005293:Ferritins / Q000096:biosynthesis; D006107:Granulosa Cells / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism*; D054315:Oocyte Retrieval; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism*; D011990:Receptors, Transferrin / Q000096:biosynthesis
chemical_list: D015703:Antigens, CD; C068126:CD71 antigen; D011990:Receptors, Transferrin; D005293:Ferritins; D007501:Iron
keywords: endometriosis; ferritin; fertility; iron; transferrin