How best to select sperm which are of good DNA content and has good morphology i,e potentiality to fertilize?

Newer   modalities    for sperm  selection and how  we can implement    them in the laboratory .

The physiological barrier or the natural selection that the sperm   has to undergo  in order to fertilize the oocyte  What are the physiological barrier or the natural selection that the sperm   has to undergo  in order to fertilize the oocyte?? Ans:- In the year     1992  it was showed by the researchers that  there was a   dramatic reduction   in the  number of sperms   recovered from the fallopian  tube  when artificially    inseminated.

 This    reduction clearly brought about a change in the thought process at that time and researchers where now focusing on the physiological barrier or the natural selection that the sperm   has to undergo  in order to fertilize the oocyte    . These   physiological  barriers   include the acidic    ph  of the vagina , cervical    mucus   response to changes   in the uterine environment   going from   the  uterus to the tubes the binding of the sperms to the zona pellucida  ect.

These mechanisms selectively reduce the amount of sperms  reaching   the egg and fertilizing   it but  amount   of sperms   reaching the egg   and fertilizing it but the question  now is   how to make   the sperm  selection equivalent to  the natural and how to improve   the existing   modalities  so as to select   the single   best sperm   the millions  that are   ejaculated.

Even   though IVF    in now    four decades   old we   still  don’t   understand  the how   effective   these sperms really   are and most judgments are basically  based  on microscopic  evaluation which   is not  the best way to judge the potential of the sperm also we know for a fact    that all motile    sperms      don’t have  the potential  to fertilise the   oocytes   and judging    the sperms   based on   motility alone again  wouldn’t   be the best way to select.

Now logically  if we try to mimic the natural    selection in the ivf   laboratory our   sperm selection     would definitely improve and hopefully     would give us better outcomes  . In this     chapter   we will try and cover    the newer   modalities    for sperm selection and how  we can implement    them in the laboratory .

 What is peculiar or specialty in Sperms  cells in any animals?? Ans:- Sperm cells (male gametes) are  by  far be considered  as the most  specialised cells in   the body they are  programmed to do the most important    task   which is to create life.  Different      parts of the sperm have different functions during    the process of fertilisation  . The 1) head  carries   the DNA   content   which has to    be delivered   to the egg the 2) mid   piece   stores   the energy  creating mitochondria    3) the  tail   carries   out the flagellar   propulsion ,

AS such the  grading and selecting    based on these  three  important components   is something  which is generally  followed worldwide.

   In ICSI procedure we know that a heavy responsibility lies on embryologist to select the best sperm for injection in the oolemma. How this selection is done? Is such sperm are the best sperms?? Now we should remember that till now most ART center  sect sperm for injection based on sperm motility   or  the sperm morphology . Such sperms are are usually selected as full marks for injection to oocytes. But is that all??  Then why there are so many cases of “Failure to progress normally after blastocyst stage” :- after implantations in ICSI procures??   The procedure of ICSI –The outcome depends mainly on judgement    of the embryologists : Having admitted that may one ask what are the limitations of sperm selection in ICSI as of now?? Ans: The limitations are even today most of the ART ( ICSI-  IVF ) the andrologist /embryologist has the option to select the best sperm under. But the limitations is that of all available methods to select the best sperm in ICSI procedure of all the  available  techniques    basically   depend on    selection the sperm   based on motility      or on the  morphology     but these don’t   really mimic any   of the natural   processes. The sperms can  then be chosen by the embryologist   on the ICSI  manipulator thus adding to the selection  process. But again these   modalities are only based  on the judgement    of the embryologist which isn’t    standardized and varies   heavily between users. The newer techniques    which have come up    and have started to  show a positive  impact as fear as results   are concerned are PICSI   or hyaluronan   binding    capacity   .

 IMSI  intra cytoplasmic   morphologically selected sperm    injection,  Microfluidies,  Magnetic   activated  sperm     sorting  and Omics.

Sperm plasma   membrane remodeling:-  PICSI:-  The  sperm plasma   membrane remodeling   is an important    step  in preparing the sperm to fertilise the egg during this processes specific    receptors  form like the zone pellucida   receptors   and the hyaluronic   acid receptors  which aid in   cumulus binding . The principle  behind   the use of PICSI is that when a mature   sperm reaches the Hyamuronic acid rich  cumulus complex surrounding the human     egg such sperm    binds   and  initiates  the final fertilisation . We should remember that the only   fully matured     sperm have developed HA  receptors  and can bind to the zone pellucida .  Immature sperm   cannot  bind to HA    .

What about sperm DNA fragmentation ?? Researchers have also noticed that failure to fertilize injected sperms in ICSI / Recurrent early pregnancy loss  may follow  in women whose husband’s sperms exhibit  have higher rates of DNA   damage and a  higher occurrence of carrying  abnormal numbers  of chromosomes . Thus  patients that  have   a high DNA  fragmentation  index or have    suffered   from recurrent miscarriages  or have poor   quality  of embryos  in multiple   cycles   can benefit   from this  technique    carried    out a Cochrane   review  in 2014  which came  to the conclusion  that more evidence   is required to come  to a conclusion  to whether or not  PICSI is actually beneficial or not .

IMSI

How best to avoid poor sperms(morphologically sperms) IMSI: Injection of morphologically selected sperms: Humans   ejaculate a considerably large number of morphologically abnormal sperms . We have a strict  criteria    to grade  the morphology    of the sperm  and also   to decide  on the treatment    options for the patients . Most  of the times  patients with  poor morphology are directed   towards        an ICSI      cycle justification being that the   embryologist  can choose   the morphologically  normal   sperms    to fertilise  the oocyte  . However recent papers     have shown  that even the sperms    which appear normal   in ICSI   can have     multiple  defects   as shown   .

Gross   evaluation    of sperms   on ICSI   magnification  that is  400x  isn’t   sufficient    to defect   subtle   aberrations which according    to some have   higher chances  of transmitting genetic as well as chromosomal diseases  . Also   there is a need to standardise the scoring system   with IMSI   as of now there   are 4  grades in which the sperms  can be classified  into the according    to the current  grading   more standardized   Cochrane   review  on IMSI  states   that      there was no significant   difference in live birth  between IMSI  and ICSI  also  no significant   difference   in pregnancy   rates or  miscarriages rtes But we   need to study   the prognosis of an IMSI  cycle vs  and ICSI   cycle in    patients who    actually have poor    parameters and  then only  we would be able to justify  the use of IMSI.

   as such

Sperm    vacuoles   have also   been researched and have   mostly been associated  with a higher DNA  fragmentation     index  but this   association  still  needs  to be proven  

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,Application of MACS   in IVF

Improves   fertilisation potential

Increases cleavage  and pregnancy   rates

Reduces   sperm DNA  fragmentation

Improves live  birth rate

But  again more systematic  reviews are needed to back   these  claims 

MICROFLUIDICS

 Microfluidics  is an exciting  technology    which   now takes   into consideration  the biophysical and biochemical  milieu which    the sperm encounters in the   Female   reproductive  tract Studies  have shown   an increase  in motile   percentage of sperm    from below  60%  to 90%  they have  also  shown   better DNA   integrity post sorting      system could  reduce  the treatment   time for   intracytoplasmic .

Conclusion

Even   though   the technological  advances  are occurring at a rapid   pace the biggest challenge  that still  remains   is justifying   these technologies  and proving   their  efficacy  with  long term    data   to support it .

 Sperm   selection  brings  forth a very   exciting   new frontier in IVF  and it takes  us closer to  achieving   our aim of    having   a single   live birth   from a single  embryo   transfer. It also   presents   us with   various challenges  as far as male  infertility   and its  management  is concerned.