Despite news reports of breakthroughs in the cryopreservation of human egg cells (unfertilized ova) over the past several years, preservation of human ova at cryogenic temperatures is still considered an experimental procedure. At 21CM, we’ve made significant cryobiological advances that are rapidly improving the prospects for making this important technology a safe and effective clinical option.
Currently, we are conducting research using laboratory animal models to develop improved procedures for mammalian oocyte vitrification, with the long-term goal of translating these advances to clinical applications; a true “Bench to Bedside” vision. We’re actively recruiting partners in assisted reproductive technology centers, fertility clinics and endocrinologists in order to further research in improving the ability of human ova to survive ‘true vitrification” by using proprietary21CM methodologies.
Advance the future of reproductive medicine: contact us toll-free at 866-889-1215
In recent years, rapid cooling methods have been shown to outperform more conventional slow-cooling methods for cryopreserving human oocytes. To solve the inherent problems of conventional cryopreservation, our scientific investigations center on a process called vitrification, a process that leads to the conversion of intracellular and extracellular liquid into an amorphous solid without the formation of crystals (i.e., to the formation of a glass, rather than ice). Vitrification as a cryopreservation method has many significant benefits, including the escape from damage stemming from both intracellular and extracellular ice formation and “outrunning” chilling injury. Furthermore, vitrification permits processing times to be shortened, expensive controlled-rate freezing devices to be dispensed with, and fluctuations in outcome due to such uncontrolled variables as varying sample-to-sample nucleation temperatures to be eliminated. Additionally, we have developed direct methods of reducing chilling injury beyond the mere reduction in time for it to occur through the use of rapid cooling.
Scientists at 21CM have been at the forefront of vitrification technology, going back to the original report on mammalian embryo vitrification co-authored by our Chief Scientific Officer, Greg Fahy, Ph.D.
We provide contract research support for reproductive technology initiatives that have a need to identify preservation methods without causing damage to the mammalian ova. Our team consists of a dedicated project manager plus technical and executive account managers who facilitate each project's design, implementation, evaluation, and ultimate commercial deployment.
Many variables in the vitrification process can profoundly influence its effectiveness. The optimal levels of these variables for human oocyte vitrification are undefined. Some of these variables include:
Embryos have been cryopreserved and stored successfully for many years. Embryos develop from fertilized eggs, and are approximately the same size as mature eggs, but more likely to survive cryopreservation. This is due in part to the fact that their sensitivity to chilling injury is dramatically reduced, partly due to changes induced in the cell membrane by fertilization.
These changes allow embryos to be cooled more slowly and therefore to more easily avoid intracellular ice formation. However, the cell shrinkage that occurs with extracellular freezing can also lead to cellular injury and death. Embryos also appear to be more able than ova to tolerate the physical and osmotic stresses associated with extracellular ice formation. All of these differences point to the use of vitrification for human oocyte cryopreservation. The most effective methods currently used to cryopreserve human oocytes using vitrification employ so-called “open” systems; systems which expose the cells directly to liquid nitrogen. Such open systems are considered to have a higher risk associated with bio-contamination, and are less desirable than techniques using closed systems.
The zona pellucida is an extracellular “shell” that surrounds the egg. It undergoes changes at the time of fertilization to prevent multiple sperm from fertilizing the egg. Cryopreserved oocytes are usually fertilized by a technique called intracytoplasmic sperm injection (ICSI), since zona damage is usually induced by current cryopreservation methods. ICSI has led to higher success rates utilizing cryopreserved oocytes, but is an intensive and expensive procedure.
Our mission is to create a cryopreservation method that minimizes or totally eliminates damage to the oocyte and zona pellucida, and allows fertilization by safer and less intensive (and expensive) methods. Furthermore, we believe that vitrification methods using fully closed systems can be developed that are at least as effective as the best methods currently available. While we believe that the superior performance and convenience of vitrification will drive the development of this technique to higher levels of clinical efficiency and utilization, much more work remains before this will be a routinely available and viable option for most people who could benefit from it.
We are pleased that our preliminary results with vitrified unfertilized mouse ova as an initial model system showed advanced embryonic development at 80% of the frequency obtained with untreated control ova after rewarming. This was particularly encouraging because in these experiments, fertilization after vitrification with mouse sperm was done without ICSI, and the development rate of 80% of control rate was obtained without subtracting any problems arising from defective fertilization after vitrification and rewarming.
These initial results were published early in 2004. See Improved Vitrification Solutions Based on the Predictability of Vitrification Solution Toxicity, Cryobiology, Volume 48, pages 22-35, 2004.