Study of Sperm Molecular Factors Implicated in Male Fertility
Condition: Male Infertility
MeSH terms: Infertility; Infertility, Male
Study type: Observational

Summary: 
      Sperm analysis following World Health Organization guidelines is unable to explain the
      molecular causes of male infertility when basic sperm parameters are within a normal range
      and women do not present gynaecological pathology.

      Subsequently, there is a need for accurate diagnostic tools in this sense and microarray
      technology applied to sperm analysis emerges as a promising field
    

Detailed description: 
      Sperm analysis based in sperm count and motility has been employed for the diagnosis of male
      fertility for several decades. It is an easy, inexpensive and useful tool to determine the
      fertile status of a male but there is still a significant number of infertile males with
      normal sperm features, as determined by the basic sperm analysis, while they remain unable to
      reach a full-term pregnancy (1). This fact clearly indicates the need to develop new male
      infertility tests and accurately diagnose the sperm samples from these individuals.

      Recent investigations about sperm mRNA contents have described the relevance of the sperm
      mRNA stock in fertilization and early embryo development in several species. (2) Although
      sperm is a quiescent cell from the translational point of view, several functional mRNAs that
      will be delivered into the oocyte after fertilization, that were synthesized in an earlier
      phase of the spermatogenesis process can be found (3, 4).

      The fertile male transcriptome (stock of mRNAs within the sperm of a male able to have
      progeny) has been already described (5, 6), confirming the expression of thousands of
      sequence tags with different intensity of expression.

      Moreover, several investigations have demonstrated that a differential expression of some key
      mRNAs is found in infertile males in comparison with fertile males (1, 7).

      Nevertheless, there is no information available neither about the characteristics of the
      stock sperm mRNAs on infertile males or the differences between fertile and infertile men,
      although several authors have hypothesized that sperm microarray analysis will be the future
      in the male infertility diagnosis (2, 8-11).

      Microarray technology provides information about a wide range of mRNAs expression within a
      single experiment, permitting to analyze complete sperm expression profiles (SEP) in cells or
      tissues. Bioinformatics can help in the organization of such amount of results by following
      logical processes of gene expression grouping, and analyzing statistically these findings.

      Our aim with this work was to compare the SEP in spermatozoa obtained from males with
      idiopathic infertility versus those from sperm donors of proven fertility by employing
      microarray technology followed by a functional analysis, in order to determine the genes,
      sequences and biological processes involved in the sperm physiology that are different in
      infertile vs. fertile males.
    

Intervention name(s): Microarray analysis; Microarray
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Microarray analysis; Microarray
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Infertile male undergoing assisted reproduction technique without abnormal sperm parameters
        described by the OMS. Female partners are under 37 years old, IBM lower than 30 kg/m2 and
        do not present any obvious infertility problem as fallopian tubal obstruction,
        endometriosis, ovarian failure or polycystic ovarian syndrome.
      
Biospecimen description: 
      After sperm washing, sperm pellet was suspended in trizol and immediately frozen by direct
      immersion in liquid nitrogen and stored in a nitrogen tank until mRNA extraction.
    
Keywords: Sperm, male fertility, microarrays