Kishlay Kumar

Bio: Kishlay Kumar is an academic researcher from John Radcliffe Hospital. The author has contributed to research in topics: Sperm & Male infertility. The author has an hindex of 11, co-authored 17 publications receiving 439 citations. Previous affiliations of Kishlay Kumar include AIIMS, New Delhi & All India Institute of Medical Sciences.

Identification of protein changes in human spermatozoa throughout the cryopreservation process.

Abstract: Summary Cryoinjury is a consequence of cryopreservation and may have a negative impact on sperm quality regarding motility, morphology, and viability. This study was designed to identify potential proteomic changes in human sperm cells throughout the cryopreservation process. Comparisons made within this study included the detection of the sperm proteomic changes induced by incubation of the sperm cells with a protein-free cryoprotectant (with and without CryoSperm), and the proteomic changes induced by freezing, thawing, and subsequent after-thawing incubation at two different temperatures (0 °C vs. 23 °C). Tandem Mass Tag (TMT) peptide labeling coupled with LC-MS/MS was used for protein quantification. LC-MS/MS resulted in the identification of 769 quantifiable proteins. The abundance of 105 proteins was altered upon CryoSperm incubation. Freezing and thawing also induced substantial protein changes. However, fewer changes were observed when semen was thawed and then maintained after-thawing at approximately 0 °C than when it was maintained after-thawing at 23 °C, with 60 and 99 differential proteins detected, respectively, as compared to unfrozen semen incubated in CryoSperm. Collectively, these differences indicate that substantial changes occur in the sperm proteome at every stage of the cryopreservation process which may ultimately impair the sperm fertilizing capability. This is the first study to compare protein levels in fresh and cryopreserved semen using the TMT technology coupled to LC-MS/MS.

Predictive value of DNA integrity analysis in idiopathic recurrent pregnancy loss following spontaneous conception.

Abstract: Purpose Standard semen parameters are poor predictors of fertility potential. To date, apart from, paternal karyotyping sperm factors are not evaluated in recurrent pregnancy loss (RPL), only recent studies have emphasized the role of sperm factors in early embryonic development as sperm transcribes genes critical for early embryonic development. Sperm DNA integrity is useful diagnostic and prognostic marker and has clinical implications in idiopathic recurrent pregnancy loss (iRPL) following spontaneous conception. The aim of this study was to assess DNA integrity in cases experiencing iRPL following spontaneous conception.

Genetic and epigenetic factors: Role in male infertility

Abstract: Genetic factors contribute upto 15%-30% cases of male infertility. Formation of spermatozoa occurs in a sequential manner with mitotic, meiotic, and postmeiotic differentiation phases each of which is controlled by an intricate genetic program. Genes control a variety of physiologic processes, such as hypothalamus-pituitary-gonadal axis, germ cell development, and differentiation. In the era of assisted reproduction technology, it is important to understand the genetic basis of infertility to provide maximum adapted therapeutics and counseling to the couple.

Cytogenetic, Y chromosome microdeletion, sperm chromatin and oxidative stress analysis in male partners of couples experiencing recurrent spontaneous abortions.

Abstract: Etiology in majority of couples experiencing recurrent spontaneous abortions (RSA) is still unknown. The aim of the study was to find the role of cytogenetic abnormalities, Y chromosome microdeletion, oxidative stress (OS) and sperm DNA fragmentation in male partners of couples experiencing RSA. Forty-eight couples with history of RSA and 20 fertile controls were included in the study. The study subjects were divided into male partners of RSA couples with abnormal sperm parameters (SA) (N = 16), male partners of RSA couples with normal sperm parameters (NS) (N = 32) and age-matched fertile controls with normal sperm parameters (FC) (N = 20). One of 48 men (2%) showed 46, XY (1qh-) chromosomal complement. None of the cases including FC showed deletion in any of the 3 AZF loci on Y chromosome long arm. Sperm count was found be significantly lower in SA cases as compared to group NS cases (P < 0.0001) and FC (P < 0.005). Sperm forward motility was found to be significantly (P < 0.05) lower in SA cases as compared to NS and FC. Male partners of RSA couples with abnormal sperm parameters had higher reactive oxygen species (ROS) levels (P < 0.005) and sperm DNA damage (P < 0.0001), however, in male partners of RSA couples with normal sperm parameters had only increased (P < 0.0001) sperm DNA damage. Other than chromosomal anomalies, sperm DNA fragmentation and seminal OS may be the underlying pathology in RSA, thus screening for seminal ROS levels and DNA fragmentation has diagnostic and prognostic capabilities.

Temporal trends in sperm count: a systematic review and meta-regression analysis.

Abstract: BACKGROUND Reported declines in sperm counts remain controversial today and recent trends are unknown. A definitive meta-analysis is critical given the predictive value of sperm count for fertility, morbidity and mortality. OBJECTIVE AND RATIONALE To provide a systematic review and meta-regression analysis of recent trends in sperm counts as measured by sperm concentration (SC) and total sperm count (TSC), and their modification by fertility and geographic group. SEARCH METHODS PubMed/MEDLINE and EMBASE were searched for English language studies of human SC published in 1981-2013. Following a predefined protocol 7518 abstracts were screened and 2510 full articles reporting primary data on SC were reviewed. A total of 244 estimates of SC and TSC from 185 studies of 42 935 men who provided semen samples in 1973-2011 were extracted for meta-regression analysis, as well as information on years of sample collection and covariates [fertility group ('Unselected by fertility' versus 'Fertile'), geographic group ('Western', including North America, Europe Australia and New Zealand versus 'Other', including South America, Asia and Africa), age, ejaculation abstinence time, semen collection method, method of measuring SC and semen volume, exclusion criteria and indicators of completeness of covariate data]. The slopes of SC and TSC were estimated as functions of sample collection year using both simple linear regression and weighted meta-regression models and the latter were adjusted for pre-determined covariates and modification by fertility and geographic group. Assumptions were examined using multiple sensitivity analyses and nonlinear models. OUTCOMES SC declined significantly between 1973 and 2011 (slope in unadjusted simple regression models -0.70 million/ml/year; 95% CI: -0.72 to -0.69; P < 0.001; slope in adjusted meta-regression models = -0.64; -1.06 to -0.22; P = 0.003). The slopes in the meta-regression model were modified by fertility (P for interaction = 0.064) and geographic group (P for interaction = 0.027). There was a significant decline in SC between 1973 and 2011 among Unselected Western (-1.38; -2.02 to -0.74; P < 0.001) and among Fertile Western (-0.68; -1.31 to -0.05; P = 0.033), while no significant trends were seen among Unselected Other and Fertile Other. Among Unselected Western studies, the mean SC declined, on average, 1.4% per year with an overall decline of 52.4% between 1973 and 2011. Trends for TSC and SC were similar, with a steep decline among Unselected Western (-5.33 million/year, -7.56 to -3.11; P < 0.001), corresponding to an average decline in mean TSC of 1.6% per year and overall decline of 59.3%. Results changed minimally in multiple sensitivity analyses, and there was no statistical support for the use of a nonlinear model. In a model restricted to data post-1995, the slope both for SC and TSC among Unselected Western was similar to that for the entire period (-2.06 million/ml, -3.38 to -0.74; P = 0.004 and -8.12 million, -13.73 to -2.51, P = 0.006, respectively). WIDER IMPLICATIONS This comprehensive meta-regression analysis reports a significant decline in sperm counts (as measured by SC and TSC) between 1973 and 2011, driven by a 50-60% decline among men unselected by fertility from North America, Europe, Australia and New Zealand. Because of the significant public health implications of these results, research on the causes of this continuing decline is urgently needed.

Oxidative stress and male infertility

Abstract: Male infertility accounts for up to half of the infertility cases and affects 13–15% couples worldwide. An optimal level of reactive oxygen species is crucial for maintaining spermatogenesis and sperm functions. However, excessive production of reactive oxygen species may cause oxidative stress. Oxidative stress has been identified as one of the major risk factors which affects the fertilizing potential of spermatozoa. Oxidative stress occurs due to excessive production of ROS and causes germ cell DNA damage, sperm fragility and defects in motility, culminating in infertility. Poor sperm quality and DNA damage may also result in pregnancy loss. This article highlights the significance of ROS in human male fertility and that of oxidative stress in infertility.

Sperm DNA damage caused by oxidative stress: modifiable clinical, lifestyle and nutritional factors in male infertility.

Abstract: DNA fragmentation is an important factor in the aetiology of male infertility. However, it is still underevaluated and its inclusion in routine semen analysis is debated. DNA fragmentation has been shown to be a robust indicator of fertility potential, more so than conventional semen parameters. Men with high DNA fragmentation levels have significantly lower odds of conceiving, naturally or through procedures such as intrauterine insemination and IVF. Couples may be counselled to proceed directly to intracytoplasmic sperm injection as it is more successful in this group, avoiding costly procedures, recurrent failures or pregnancy losses; however, this treatment is not without limitations or risks. Ideally DNA fragmentation should be minimized where possible. Oxidative stress is the major cause of DNA fragmentation in spermatozoa. Endogenous and exogenous factors that contribute to oxidative stress are discussed, and in many cases are shown to be easily modifiable. Antioxidants play a protective role, although a delicate balance of reduction and oxidation is required for essential functions, including fertilization. Reducing oxidative stress may improve a couple's chances of conception either naturally or via assisted reproduction. Sources of oxidative stress therefore should be thoroughly examined in men with high levels of DNA fragmentation and modified where possible. DNA fragmentation is an important factor in the aetiology of male infertility. However it is still underevaluated and its inclusion in routine semen analysis is still debated. DNA fragmentation has been shown to be a robust indicator of fertility potential, more so than conventional semen parameters. Men with high levels of DNA fragmentation will have significantly lower odds of conceiving naturally or through procedures such as intrauterine insemination and IVF. Intracytoplasmic sperm injection (ICSI) may be much more successful in this group, and couples may be counselled to proceed directly to ICSI, avoiding costly procedures, recurrent failures or pregnancy losses. However, ICSI is not without its limitations or risks. Ideally, DNA fragmentation should be investigated and minimized where possible in men trying to conceive naturally or through assisted reproduction technology. Oxidative stress is the major cause of DNA fragmentation in spermatozoa. Endogenous and exogenous factors that contribute to oxidative stress are discussed and in many cases are easily modifiable. Antioxidants play a protective role, although a delicate balance of reduction and oxidation is required for essential sperm function, including fertilization. Reducing oxidative stress may improve a couple's chances of conception either naturally or via assisted reproduction treatment. Sources of oxidative stress therefore should be thoroughly examined in men with high levels of DNA fragmentation and modified where possible.

Impact of obesity on male fertility, sperm function and molecular composition.

Abstract: Male obesity in reproductive-age men has nearly tripled in the past 30 y and coincides with an increase in male infertility worldwide. There is now emerging evidence that male obesity impacts negatively on male reproductive potential not only reducing sperm quality, but in particular altering the physical and molecular structure of germ cells in the testes and ultimately mature sperm. Recent data has shown that male obesity also impairs offspring metabolic and reproductive health suggesting that paternal health cues are transmitted to the next generation with the mediator mostly likely occurring via the sperm. Interestingly the molecular profile of germ cells in the testes and sperm from obese males is altered with changes to epigenetic modifiers. The increasing prevalence of male obesity calls for better public health awareness at the time of conception, with a better understanding of the molecular mechanism involved during spermatogenesis required along with the potential of interventions in reversing these deleterious effects. This review will focus on how male obesity affects fertility and sperm quality with a focus on proposed mechanisms and the potential reversibility of these adverse effects.

A paternal environmental legacy: Evidence for epigenetic inheritance through the male germ line

Abstract: Literature on maternal exposures and the risk of epigenetic changes or diseases in the offspring is growing. Paternal contributions are often not considered. However, some animal and epidemiologic studies on various contaminants, nutrition, and lifestyle-related conditions suggest a paternal influence on the offspring's future health. The phenotypic outcomes may have been attributed to DNA damage or mutations, but increasing evidence shows that the inheritance of environmentally induced functional changes of the genome, and related disorders, are (also) driven by epigenetic components. In this essay we suggest the existence of epigenetic windows of susceptibility to environmental insults during sperm development. Changes in DNA methylation, histone modification, and non-coding RNAs are viable mechanistic candidates for a non-genetic transfer of paternal environmental information, from maturing germ cell to zygote. Inclusion of paternal factors in future research will ultimately improve the understanding of transgenerational epigenetic plasticity and health-related effects in future generations.