The study by researchers at Massachusetts General Hospital (MGH), published in the Advanced Online Publication of Nature Medicine, showed that egg-producing stem cells from the ovaries of reproductive-age women can produce what appear to be normal egg cells or oocytes . The team from the Vincent Center for Reproductive Biology at MGH reported the results as a follow-up to their 2004 Nature paper that first suggested female mammals continue producing egg cells into adulthood.
“The primary objective of the current study was to prove that oocyte-producing stem cells (OSCs) do in fact exist in the ovaries of women during reproductive life, which we feel this study demonstrates very clearly,” Jonathan Tilly, director of the Vincent Center for Reproductive Biology at MGH and co-founder of OvaScience, said in a statement. OvaScience has licensed the technology from MGH. “The discovery of oocyte precursor cells in adult human ovaries, coupled with the fact that these cells share the same characteristic features of their mouse counterparts that produce fully functional eggs, opens the door for development of unprecedented technologies to overcome infertility in women and perhaps even delay the timing of ovarian failure,” he added.
Tilly said the paper provides three key pieces of evidence that skeptics of previous work have wanted to see. “We developed and extensively validated a cell-sorting protocol to reliably purify OSCs from adult mammalian ovaries, proving once again that these very special cells exist,” he said. “We tested the function of mouse oocytes produced by these OSCs and showed that they can be fertilized to produce healthy embryos. And we identified and characterized an equivalent population of oocyte-producing stem cells isolated from adult human ovaries.”
In the study, Tilly and his colleagues developed a strategy to purify egg precursor cells from ovaries of adult female mice and ovaries from reproductive-age women. Reintroduction of mouse egg precursor cells into adult mouse ovaries led to the maturation of new eggs that could be ovulated and fertilized into healthy embryos.
Scott Chappel, chief scientific officer of OvaScience, said the research, “has the potential to enable the development of new treatment options for infertility.” OvaScience has an exclusive U.S. patent license to an issued U.S. patent containing composition claims covering the isolated egg precursor cells discovered by Tilly.
Some 6.1 million women in the United States of reproductive age have difficulty getting or staying pregnant, according to the Centers for Disease Control and Prevention. And, 60 percent of in vitro fertilization (IVF) cycles are performed in women aged 35 or older. In women over 40, IVF has less than a 15 percent success rate. OvaScience hopes its technology can improve those odds.Among the potential clinical applications findings that Tilly’s team is currently exploring are the establishment of human OSC banks since these cells, unlike human oocytes, can be frozen and thawed without damage.
Privately held OvaScience was co-founded by Rich Aldrich, Dr. Michelle Dipp and Dr. Christoph Westphal of Longwood Fund and Professors Tilly and David Sinclair, both of Harvard Medical School. The three Longwood partners previously worked with Sinclair at Sirtris Pharmaceuticals. OvaScience received a $6 million Series A round from Longwood and Bessemer Venture Partners. The company has 10 employees.
“The company began in January of last year with the idea of in-licensing two technologies, one from Mass General Hospital and one from Harvard Medical School,” Chappel, who was previously with Serono and Dyax, told Mass High Tech when the company came out of stealth mode. One technology is from Tilly, and the other is from Sinclair, who studies aging and the function of mitochondria, which provide the energy a cell needs to function and divide.
“The vision Longwood had was to marry the two technologies so their combination could be used to improve IVF outcomes at fertility clinics,” Chappel added. “We hope that with the improved quality of the oocyte, we will be able to decrease the number of embryos that need to be transferred, avoiding multiple births and minimizing the risk of medical issues.”
Dipp expects the company’s product, which will be a mix of a service and the energy-rich mitochondria isolated from the egg stem cell, to initially be used by women who failed IVF a couple times, but eventually by all patients. Following the clinical trial, the company plans launch a product in 2013.