At a Glance
- Researchers restored a single protein to youthful levels in aging eggs
- Treated human eggs showed a 46% drop in chromosome-separation errors
- The technique could extend IVF viability for women over 40
- Why it matters: Older women face steep odds in IVF; this may shift the odds back
Scientists report they have partially reversed a key defect that causes IVF failure in older women. By replenishing one protein that declines with age, they sharply reduced the rate of abnormal chromosome separation in eggs.
The Chromosome Problem
A viable embryo needs 46 chromosomes-23 from the egg, 23 from the sperm. Before fertilization, egg cells must halve their DNA through meiosis. Mistakes during this split produce aneuploid eggs, a condition that skyrockets after age 35.
- Under 35: ~20% of eggs are aneuploid
- Over 40: more than 50% are aneuploid
- Aneuploidy is the leading cause of failed implantation and miscarriage in IVF
Protein Rescue in Lab Tests
Melina Schuh’s team at the Max Planck Institute zeroed in on Shugoshin 1 (SGO1), a protein that keeps chromosome pairs aligned until the exact moment of separation. Prior work showed SGO1 levels fall as eggs age.
Study design:
- Microinjected purified SGO1 into mouse and human eggs
- Human eggs were surplus patient samples from a fertility clinic
- Compared chromosome segregation in treated vs. untreated cells
Results in human eggs:
| Condition | Improper Separation Rate |
|---|---|
| No treatment | 53% |
| + SGO1 | 29% |
More than half of untreated eggs mis-segregated chromosomes, while fewer than one-third of treated eggs did.
Next Hurdles
The study, posted on bioRxiv, has not yet been peer-reviewed. The group will present data at the British Fertility Conference in Edinburgh.
Open questions:
- Do lower error rates translate into live births?
- Can SGO1 delivery be scaled to clinical-grade safety?
- Will the method work in women who have already entered menopause? (Researchers doubt it)
Schuh and colleagues launched Ovo Labs to pursue further development and eventual commercialization.
Güneş Taylor, a fertility researcher at the University of Edinburgh not involved in the work, called the approach critical: “We need methods that work for older eggs, because that’s when most women seek IVF.”
Key Takeaways
- A single-protein fix cut chromosome errors by nearly half in lab eggs
- If replicated, the technique could make IVF less of a gamble for women over 40
- Safety and efficacy trials must still clear regulatory review before any clinical use
