Spermatozoa Vitrification Using Sucrose-Based Medium
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Solution Overview
Problem
Conventional cryopreservation techniques for spermatozoa, such as freezing, result in significant reduction in motility due to intracellular ice crystal formation, are costly, and limited by the need for liquid nitrogen storage, making them inefficient and inaccessible to many.
Innovation Solution
A vitrification method using a 0.25 M sucrose-based vitrification medium with dextran and albumin, allowing for aseptic preservation of spermatozoa without permeable cryoprotectants, enabling storage at -80°C and efficient devitrification without special equipment, thus reducing costs and maintaining high motility and DNA integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional freezing methods are used for spermatozoa cryopreservation, then spermatozoa can be preserved, but motility is significantly reduced due to intracellular ice crystal formation
Solution Approach 1:
The patent applies vitrification, a phase transition technique where the cryoprotectant solution transforms from liquid to glass-like solid state without forming ice crystals. This is achieved by rapid cooling of spermatozoa suspended in a specific cryoprotectant solution containing permeating agents (glycerol, ethylene glycol, or propylene glycol) and non-permeating agents (sucrose, dextran, and serum albumin), preventing intracellular ice crystal formation that would otherwise damage sperm membranes and reduce motility.
2Reliability
If traditional spermatozoa freezing methods are used, then preservation is achieved, but the cost is high due to liquid nitrogen storage requirements
Solution Approach 1:
The patent changes the storage temperature parameter from traditional liquid nitrogen temperatures (-196°C) to standard ultra-freezer temperatures (-80°C). This is made possible by the optimized cryoprotectant solution composition that enables vitrification and prevents ice crystal formation, allowing spermatozoa to be stored in conventional ultra-freezers without specialized cryogenic equipment, thereby significantly reducing operational costs.
3Reliability
If conventional freezing techniques are used, then spermatozoa can be preserved, but the process is complex and requires specialized equipment
Solution Approach 1:
The patent utilizes the vitrification phase transition to eliminate the need for complex specialized cryogenic equipment. By transforming the cryoprotectant solution into a glass-like state through rapid cooling in standard ultra-freezers, the method replaces complex liquid nitrogen handling systems with conventional freezing equipment, simplifying the overall preservation process while maintaining reliability.
4Reliability
If permeable cryoprotectants are used in freezing, then cryopreservation is achieved, but cellular damage occurs due to cryotoxic effects on intracellular organelles and plasmatic membrane
Solution Approach 1:
The patent employs a composite cryoprotectant system combining multiple permeating agents (glycerol, ethylene glycol, or propylene glycol) with non-permeating agents (sucrose, dextran, and serum albumin) in specific concentrations. This composite formulation provides synergistic protection: permeating agents prevent intracellular ice formation, while non-permeating agents maintain extracellular osmolarity and stabilize membranes, collectively reducing cryotoxic damage to sperm cells during vitrification.
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 achieves over 80% acrosomal integrity and 60% unaltered mitochondrial membrane potential in spermatozoa, with a significant reduction in osmotic damage and crystallization, offering a cost-effective and efficient preservation of sperm function.
Implementation Method 1
Vitrification is an extremely fast cryopreservation method that requires less execution time, is safer and has a lower effective cost than traditional freezing. Vitrification has been widely investigated for embryos and oocites
Implementation Method 2
Vitrification is carried out in small volumes in such a way as to immerse the sample directly in liquid nitrogen to increase the cooling rate and decrease ice crystal formation
Implementation Method 3
The method achieves over 80% acrosomal integrity and 60% unaltered mitochondrial membrane potential in spermatozoa, with a significant reduction in osmotic damage and crystallization
Data Source
AI summary
The present invention discloses a method for cryopreservation of human spermatozoa: the method comprises providing spermatozoa free from seminal liquid; mixing the spermatozoa with vitrification medium, wherein the main cryoprotectant agent is 0.1 -0.3 M sucrose; placing the sample inside straws and rapidly freezing them; refrigerating the straws with no need of liquid N2; and devitrifying the sample in a medium of the present invention. The present invention furthermore discloses a portable kit that makes easy to implement the method, said kit comprising vitrification and devitrification solutions in the volumes required to develop the method and the physical support to carry out the same, i.e. the straws. The use of this kit is also disclosed for the treatment of disorders related to reproductive failures.