Project Objectives

• Determine whether recombinant PMSG (pregnant mare serum gonadotropin) must be produced in equine chorionic girdle cell lines to achieve correct structure and biological activity.
• Optimise recombinant PMSG production for large-scale in‑vitro manufacturing.
• Develop GMP‑compatible purification processes for recombinant hormone extraction.
• Establish non‑inferiority between recombinant PMSG and traditional PMSG in standard in‑vivo assays.
• Validate efficacy in mice and pigs, the major target species.

3Rs Impact

• Supports full replacement of horse‑derived PMSG by providing a credible in‑vitro alternative.
• Reduces global reliance on pregnant mares, addressing serious welfare concerns.
• Decreases animal use in breeding programme, once a validated recombinant alternative becomes available.
• Improves consistency and safety by creating a standardised, quality‑controlled hormone product.
• Enables regulatory shifts and potential import bans on blood‑derived PMSG, substantially reducing animal harm.

Background

Pregnant mare serum gonadotropin (PMSG) is widely used in agriculture to synchronise ovulation in livestock and in biomedical research to induce superovulation in laboratory rodents. Despite its importance, PMSG is currently obtained exclusively from the blood of live pregnant horses. Reports indicate that up to 10 litres of blood may be drawn weekly from each mare during early gestation, with animals cycled repeatedly through pregnancies over their lifetimes. Investigations into some South American production sites have revealed serious welfare issues, including excessive blood extraction leading to anaemia, inadequate veterinary care, forced restraint of semi‑wild horses, and, in some cases, induced miscarriage to restart production more quickly. Several European facilities have also been labelled non‑compliant with EU welfare standards, prompting growing calls for import restrictions within Switzerland.

Despite clear ethical concerns, no viable animal‑free PMSG alternative has reached the market. Previous attempts to produce recombinant PMSG in cell‑based systems have not been successful, largely because the hormone’s complex structure is difficult to reproduce. This project aims to overcome this barrier by investigating whether specialised chorionic girdle cells (the natural source of PMSG) can be immortalised to produce a fully functional recombinant hormone. If successful, this would provide an ethical, scalable, and consistent replacement for PMSG without relying on pregnant horses.