Artificial Sperm Reinvented
Do you really know that the world isn’t flat? C’mon, tell the truth. In fact, debate raged on whether the earth is flat or spherical from the 8th century BC well into the second millennium (1520) AD, well over 2000 years! Magellan and scientific proof ended up nailing the truth. In the mystical words of Justin Timberlake: “What goes around, comes around.”
All Grown Up
There’s another scientific reinvention occurring at this time in the small parts world of artificial sperm. The issue is maybe we don’t actually need sperm with tails to make babies, a concept that’s been around since the beginning of sex. Maybe all we need is a tailless, pre-sperm cell, the spermatid, to make sparks fly.
Some two decades ago, a man named Yanagimachi, a tireless and brilliant reproductive biologist in Hawaii, cloned mice. He did this right after the cloning of Dolly the sheep in Europe, proving it could be done in other mammalian species. A couple of years earlier, though, he created normal mice offspring using IVF with spermatid injections. The world was taken off guard, as no one believed that the cell just before a sperm could make a normal anything. The genetics weren’t right and epigenetic imprints were likely incomplete. Despite this, round nuclear spermatid (ROSI) injections were quickly adopted in the human IVF setting with terrible success, and then abandoned entirely.
Until now. That is, until the publication of two papers from research groups half a world apart recently that showed that spermatids might be A-O-K for IVF thank you. One of these papers hails from none other than Yanagimachi himself, who, through careful analysis of the various shapes and sizes of spermatogenic cells, reported the normal birth and development (physical and epigenetic) of 14 children to 12 women using spermatids. It took 76 women over 200 IVF cycles to get these kids, but it worked.
Add to this, scientists from Nanjing Medical University in China just reported turning mouse stem cells (embryonic) into spermatids in the laboratory and then using these man made, pre-sperm cells for IVF-ICSI to create mice pups. Drilling deeper, they demonstrated that these manufactured tailless sperm plowed through the unique process of meiosis without a hitch while in the lab dish. That is, they correctly kept the genetic “marks” of their parents, and properly halved the number of chromosomes they started with. Just like real sperm.
So, why are these papers so consequential? Because for as long as I have been in this field, we have assumed that spermatids were not sperm. Couldn’t act like them, nor do the jobs that they do, as well as they do. But maybe they can. Maybe not as efficiently as sperm but just as safely. Wow. The world is not flat after all.