The center's mission is to conduct cutting-edge research in human reproduction and into the causes of male infertility while training physicians and scientists with a commitment to advance the field of reproductive sciences and research.
One of the major goals of our Center is to better understand the causes of infertility and to design studies aimed at understanding and improving semen quality. We hope this line of research will eventually result in strategies that will enable us to use the healthiest spermatozoa for fertilization to improve the chances of pregnancy. The fertilizing potential of sperm depends on the shape of the spermatozoa, the ability of the spermatozoa to perform the functions necessary for fertilizing an egg, and finally, the transfer of intact genetic material (DNA) to the egg at the time of fertilization. Abnormal spermatozoa are not fully mature, and when in the presence of white blood cells, they can produce harmful substances. These substances are very unstable and reactive molecules that are called free radicals. Other substances called antioxidants, which are present in normal healthy seminal ejaculates, reduce the harmful effects of free radicals by neutralizing them. However, infertile patients who have abnormal semen often have antioxidants that are ineffective neutralizers. This results in a preponderance of free radicals, which in turn results in a situation called oxidative stress. Oxidative stress can damage the DNA of the spermatozoa and prevent them from fertilizing an egg.
We are currently involved in projects evaluating oxidative stress in further understanding the underlying mechanism of oxidative stress in male infertility. A novel alternative to measurement of reactive oxygen species by the chemiluminescence method has been standardized. It is called oxidation reduction potential or ORP. It can be measured by a MiOXSYS system consisting of an Analyzer and sensor strips. It is a direct measure of oxidative stress in a given biological system such as semen sample. It is a direct measure of oxidative stress and can be used as a stand-alone test or in conjunction with semen analysis. Oxidative stress is also involved in the pathology of varicocele, which is the most common treatable cause of male infertility. Similarly, cancer patients diagnosed with testicular cancer or Hodgkin’s lymphoma are young and in their reproductive years. Sperm banking is recommended before cancer treatment. Sperm quality in these men is poor and this further deteriorates following freezing. We have established a proteomic platform utilizing bioinformatics tools to understand the major protein alteration in various biological pathways, functions and processes that affect reproductive processes and render the sperm dysfunctional. The current focus is to understand the underlying molecular mechanism of sperm dysfunction and identify alteration in major proteins in men diagnosed with male infertility. Our goal is to identify potential biomarkers that can be used in the diagnosis of male infertility utilizing proteomic analysis as a major tool.
Proteomic profile of seminal plasma in men with primary and secondary infertility
This project will study alterations in seminal plasma proteins from fertile men and men with primary and secondary infertility using proteomic/bioinformatics tools. The goal is identify differentially expressed proteins that are important for fertility. These identified seminal plasma proteins may serve as biomarkers of primary and secondary infertility.
Major alterations of spermatozoa proteins in men with Hodgkin’s disease undergoing sperm banking prior to cancer therapy
This project will identify alterations in sperm proteins in men with Hodgkin disease prior to cancer therapy. Proteomic/bioinformatics tools will be used to analyze the spermatozoa proteome. Key proteins associated with reproductive functions affecting sperm quality will be identified and validated to help understanding the poor sperm quality before cancer treatment.
Proteomic analysis of spermatozoa and seminal plasma proteins in ROS positive and ROS negative fertile men
The aim of this study is to investigate the mechanisms by which some men with significantly high levels of reactive oxygen species (ROS) are still fertile. The use of proteomic and bioinformatics tools will allow us to identify potential intervention modalities for infertile men with high ROS.
Sperm protein alterations in men with testicular cancer undergoing sperm banking prior to cancer therapy
This project is focused in studying the molecular mechanisms responsible for decreased sperm quality in men with testicular cancer prior to cancer therapy. The proteomic evaluation of sperm protein alterations in men with testicular cancer relative to fertile donors may help to find new biomarkers for diagnostic purposes.
Proteomic profile of seminal plasma proteins in varicocele patients
The focus of this study is to identify the role of seminal plasma proteins associated with sperm functions in infertile men with varicocele. A global proteomic approach will be followed to delineate the involvement of exosomal proteins in sperm maturation. Further validation of the key proteins will be carried out by immunoblotting. The findings of this study will help in the identification of novel seminal plasma protein biomarkers associated with varicocele and infertility.
MiOXSYS as a novel method to determine ORP levels in semen and seminal samples
In our initial studies, we demonstrated the ability of MiOXSYS system to measure ORP in fresh and frozen semen or seminal plasma samples. These measurements are stable up to 120 minutes. ORP measurement is rapid (<4 min) and requires only 30 µL of sample. ORP is negatively correlated with semen concentration/total sperm count, despite the fertility status.
ORP as a novel clinical test for assessment of sperm quality
We established elevated levels of ORP in infertile men (6.22 ±1.10 mV/106 sperm/mL) compared with controls (1.59 ± 0.29 mV/106/mL) (P=0.004). A cut-off of 1.36 mV/106 sperm/mL distinguishes normal and abnormal semen with a sensitivity 69.6%, specificity 83.1%, positive predictive value (PPV) 85.3% and negative predictive value (NPV) of 65.9%. We demonstrated that ORP levels negatively correlate with semen parameters (concentration, total sperm count, motility and morphology) and therefore ORP can be used as a stand-alone test or as a surrogate marker of poor sperm quality.
Impact of precise modulation of ROS levels on sperm proteins
For this study, spermatozoa were separated from 42 infertile men and 17 fertile donors into three groups based on low (0-<93 RLU/s/106 sperm), medium (>93-500 RLU/s/106 sperm) and high ROS (>500 RLU/s/106 sperm). For proteomic analysis, each group consisted of pooled samples from 4 subjects. A total of 1035 proteins were identified in the 3 ROS groups by global proteomic analysis. 305 DEPs were identified of which 51 were unique to low ROS group, 47 medium ROS group and 104 to the high ROS group. 6 DEPs (Calmegin, Tripeptidyl peptidase II, Dynein intermediate chain 2, axonemal, Heat shock 70 kDa protein 4L, Early endosome antigen 1, and Plasma serine protease inhibitor) were identified that are involved in distinct reproductive functions and were expressed only in the 3 ROS groups but not in the fertile men.
Proteomic analysis of ejaculated sperm from fertile men
We examined proteins that may be altered during the process of sperm maturation and may be responsible for male infertility. Sperm were separated into 4 fractions on a three layer density gradient. F1 contained the most immature sperm and F4 had the most mature, highly motile and morphologically normal sperm. Functional annotations of proteins were obtained using bioinformatics tools and pathway databases. 1469 proteins were identified and the number of proteins identified decreased with increasing maturation level of the sperm. During sperm maturation, proteins involved in gamete generation, cell motility, energy metabolism and oxidative stress showed increasing expression and those involved in protein biosynthesis, protein transport, protein ubiquitination, and response to oxidative stress precursors showed decreasing expression level. We have demonstrated proteins that are involved in different stages of sperm maturation and may be altered or modified in infertile men.
Proteomic signatures of infertile men with clinical varicocele
We compared the fertile group with both unilateral and bilateral group to identify the signature proteins related with varicocele-associated male infertility irrespective of the stage and laterality of their clinical varicocele. Ninety nine proteins were differentially expressed in the varicocele group. Over 87% of the DEPs were involved in energy metabolism and key sperm functions that were underexpressed in the varicocele group. Key proteins affected were spermatogenesis, sperm motility, and mitochondrial dysfunction. Expression level of 5 proteins (PKAR1A, AK7, CCT6B, HSPA2, and ODF2) involved in stress response and sperm function including molecular chaperons was validated by western blotting. We have demonstrated that varicocele is an essentially a state of energy deprivation, hypoxia and hyperthermia due to impaired blood supply. This was also demonstrated by the downregulation of lipid metabolism, mitochondrial electron transport chain and enzymes of Krebs cycle.