Moving closer to ‘true’ equine IVF for clinical use
Researchers at Penn Vet are exploring different processes for using frozen-thawed semen to accomplish so-called true IVF.
2 min. read
Three years ago, Penn Vet researchers reported a major breakthrough in equine assisted reproduction:
Katrin Hinrichs, Harry Werner Endowed Professor of Equine Medicine in Penn’s School of Veterinary Medicine, and colleagues developed a technique that would allow successful conventional in vitro fertilization (IVF) with horses. In conventional IVF, the sperm does its job of finding and fertilizing a mare’s egg, or an oocyte, in a petri dish. Since the mid-1990s, the solution has been to do ICSI (intracytoplasmic sperm injection) to produce horse embryos in vitro; the problem was it only worked with fresh sperm.
Katrin Hinrichs, chair of the Department of Clinical Studies–New Bolton Center and head of the Penn Equine Assisted Reproduction Laboratory (PEARL) and Matheus Felix, PEARL’s chief embryologist, work together in the lab. Felix is also an author in the 2025 study report on IVF with frozen-thawed stallion sperm.
(Image: Courtesy of Penn Vet)
“There is no laboratory that just happens to have the 200 best stallions in the world standing outside ready to give them fresh semen,” says Hinrichs, who heads the Penn Equine Assisted Reproduction Laboratory and is chair of the Department of Clinical Studies-New Bolton Center. “So, for commercial use, as well as to make it easy to do research, you have to be able to do IVF with frozen semen.”
Freezing and thawing, however, can result in complex changes in horse sperm. Many of the sperm die, and those that survive have modifications of their membranes and internal components. Initial trials on IVF with frozen-thawed semen were unsuccessful.
In a new Biology of Reproduction article, Hinrichs and colleagues explored different processes for using frozen-thawed semen to accomplish so-called true IVF.
Since many sperm don’t survive freezing and subsequent thawing, different methods can be used to separate out the viable sperm. Hinrichs’ team found that a commercial, filter-based sperm separation device yielded higher fertilization results than two other commonly used approaches for harvesting viable sperm, the swim-up method and colloid centrifugation.
This story is by Rita Giordano. Read more at Penn Vet.
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