Aseptic Sperm Vitrification Using Cryoprotectant Straw Freezing
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Solution Overview
Problem
Current non-aseptic sperm freezing methods result in low post-devitrification motility recovery rates, typically ranging from 20% to 30%, and lack aseptic vitrification protocols, which are critical for maintaining sperm viability and integrity.
Innovation Solution
A method involving aseptic vitrification using a permeable and non-permeable cryoprotectant mixture, combined with vertical immersion in liquid nitrogen, achieves rapid vitrification and devitrification, enhancing sperm motility recovery to 80-95%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-aseptic freezing methods are used, then the process is simpler, but post-devitrification motility recovery is low (20-30%)
Solution Approach 1:
The method applies preliminary aseptic processing and cryoprotectant treatment before vitrification to ensure sperm viability is maintained throughout the freezing and thawing process, resulting in 80-95% motility recovery
Solution Approach 2:
The invention uses composite cryoprotectant formulations containing multiple agents (e.g., glycerol, ethylene glycol, sucrose) working together to protect sperm membranes and structures during rapid freezing, achieving high recovery rates while maintaining process feasibility
2Speed
If direct contact with liquid nitrogen is used, then vitrification is faster, but sperm viability and integrity deteriorate
Solution Approach 1:
The method introduces cryoprotectant solutions as intermediary substances between the sperm and liquid nitrogen, allowing rapid heat transfer while chemically protecting sperm membranes from freezing damage, achieving both speed and integrity
Solution Approach 2:
The invention optimizes multiple parameters including cryoprotectant concentration (15-25%), exposure time (5-15 minutes), and freezing rate to achieve optimal balance between rapid vitrification and sperm preservation, resulting in 80-95% motility recovery
3Reliability
If aseptic vitrification with cryoprotectants is used, then sperm viability is maintained, but the process becomes more complex
Solution Approach 1:
The method incorporates preliminary aseptic processing and standardized cryoprotectant treatment protocols before vitrification, ensuring sperm viability is maintained throughout the process while providing clear procedural guidance for implementation
Solution Approach 2:
The invention establishes optimized parameter ranges (cryoprotectant concentration 15-25%, exposure time 5-15 minutes) that balance effectiveness with practical feasibility, making the complex aseptic process reproducible and implementable in clinical settings
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly improves sperm motility, viability, and acrosome integrity post-devitrification, reducing DNA fragmentation, making it suitable for donor and patient samples in sperm banks and assisted reproduction.
Implementation Method 1
Mixing the liquefied semen from stage (i) with the vitrification medium from stage (ii)... a cryoprotectant mixture, including a permeable cryoprotectant and a non-permeable cryoprotectant
Implementation Method 2
immersing it vertically in liquid nitrogen in a trapezoidal or rectangular or 'V' shaped container for a period of time between 10 and 20 seconds to vitrify the mixture
Implementation Method 3
The invention provides a simple, fast and effective method of human sperm vitrification... immersing it vertically in liquid nitrogen... to vitrify the mixture
Implementation Method 4
Sealing both ends of the straw with heat
Data Source
Figure 1
Figure 2A~2B
AI summary
This invention describes a method for human sperm vitrification, which includes providing liquefied human sperm; having a vitrification medium, where the vitrification medium comprises: (a) a sperm buffer, and (b) a cryoprotectant mixture including a permeable cryoprotectant and a non-permeable cryoprotectant; mixing the liquefied sperm with the vitrification medium; providing a sperm straw and loading such straw with 0.25 to 0.5 mL of the obtained mixture; sealing the straw with heat; and placing the straw vertically in a container with liquid nitrogen to vitrify the mixture. This invention also provides a portable kit, which makes it easy to implement the method. Such kit includes a vitrification medium, some straws, a container, usage instructions, among others.