Cryopreservation Of Human Spermatozoa Based On Microfluidic Technology

Objective To explore the stpes of fabrication of alginate microcapsules by microfluidic system and influence of flow velocity on size of microencapulation.Develep a cryopreservation protorol for sperm using alginic acid microcapsules.Methods The two syringes were loaded with sodium alginate solution and mineral oil respectively,microfluidic device connected.Adjusted the flow velocity,collection the alginate microcapsules.Sperm were collected and centrifuged.The pellet was resuspended with sperm wash and divided into four groups(A,B,C,D),group A : vitrification of sperm in alginic acid microcapsules with cryoprotectant;Group B: vitrification of sperm in alginic acid microcapsules without cryoprotectant,group C: cryopreservation of sperm in alginic acid microcapsules with cryoprotectant;Group D: traditional slow freezing of sperm.Alginic acid microcapsules were produced using microfluidic system,then were cryopreserved for 24 h.Total survival rates of sperm and rates of motile sperm were compared among groups after thawing.Results When we increased the rate of alginate or mineral oil flow,microspheres size were reduced.Setting the flow rates of alginate and mineral oil as 20?L/min and 450?L/min,the diameter of microcapsules were around 200 ?m and were uniform on size.After thawing,motile rates of four groups were significantly different with fresh sperm(rates of motile sperm were(63.4±2.7)%,progressively motile rates were(53.6±3.8)%,(p<0.05),especially in group A and B.Rates of motile sperm(17.5±2.4)% and(18.9±6.7)%and progressively motile sperm were lowerthan group Cand D,(12.1±5.3)% and(11.3±5.2%),(p<0.05),rates of motile sperm were significantly different between group C and D(p<0.05).Total survival rates of sperm of four groups were significantly different with the rates before cryopreservation(69.7±3.1)%,(p<0.5).Rates of group A and B were lower than goup C and D,but there was no statistically differences between two groups.Conclusion Alginate microcapsules can be made using microfluidic system.Slow freezing of sperm encapsulated in alginic microcapsules can be an option for cryopreservation of small numbers of sperm with good recovery rate.