Unfertilized human eggs activated in the laboratory, termed “parthenotes,” can divide into stem cells with the capacity to develop into any body tissue type.
Parthenote Stem Cells hold three key advantages:
- It may be easier to genetically customize parthenote stem cells than other types of stem cells
- Parthenote stem cells can be either patient-specific, thus avoiding many tissue rejection problems, or it may be possible to tissue-match them to patients in need
- Parthenote stem cells could bypass some of the moral and ethical issues associated with fetal and embryonic stem cells.
Foundation scientists are currently improving the efficiency of deriving parthenote stem cells from mouse eggs. To better understand the development of parthenotes, it is helpful to review the development of fertilized mouse eggs.
Foundation scientists are deriving new stem cell lines from fertilized mouse eggs in fully defined, protein-free culture medium, GEM (Gamete Embryo Medium). GEM is a specialized fluid that simulates fluids in the womb. The goal of these experiments is to improve the efficiency of deriving new stem cell lines from parthenotes. By studying time lapse videos of developing mouse embryos, Foundation scientists will pinpoint the exact time to add stem cell growth factors to the culture medium.
Like all mammalian eggs, fertilized mouse eggs are huge cells that undergo several cleavage divisions before entering the uterus for further development. Each day is marked in this video, watch for these stages:
Day 1: Eggs are fertilized and cleave to the 2-cell stage
Day 2: 4-cell stage
Day 3: Morula (8 to 16 cells)
Day 4: Early blastocysts (40-60 cells)
Day 5: Hatching blastocysts (120-250 cells) This when the embryos could implant in the uterus for further development.
GEM, Bedford Research Foundation’s protein-free, chemically-defined embryo culture medium, supports the development of fertilized mouse eggs to blastocysts, the stage at which embryonic stem cells are derived. This unique culture medium has been more than 20-years in the making and is formulated based on the results of experiments designed to determine the most supportive in vitro conditions for assisted reproduction and embryo manipulation (references). The Foundation has made this medium available for research, academic and educational purposes – more info here.
History at the Foundation
In 2001, Foundation trustee, Dr. Jose Cibelli, used monkey eggs to report the first derivation of primate parthenote stem cells. Scientists throughout the world are now using the monkey parthenote stem cells for various studies, including one that alleviates Parkinson’s disease in a monkey model. Dr. Cibelli and Foundation, Director Dr. Ann Kiessling, extended this work to human eggs in 2002. Their pioneering research showed that like monkey eggs, human eggs could be activated in the lab to divide into many cells, giving hope that a line of human parthenote stem cells could be developed.