Mechanical biomarkers for oocyte and embryo viability
Provided are methods for the determination of the viability of a mammalian embryo or a potential embryo generated from a mammalian oocyte, comprising applying a mechanical stimulus to the embryo or oocyte, detecting a temporal response of the embryo or oocyte to the mechanical stimulus, and deriving measurements for one or more parameters from the temporal response, the measurements being indicative of viability. Also provided are methods for selecting an embryo for transfer and methods for enhancing the viability of an embryo or oocyte.
1. A method for determination of a viability of a mammalian embryo or a potential embryo generated from a mammalian oocyte, comprising:
applying a negative and substantially constant pressure using a pipette on a portion of a surface of the embryo or oocyte to inflate the embryo or oocyte at the portion but not to damage the embryo or oocyte, said substantially constant pressure having an average pressure of −0.3 psi to −1 psi and a maximum pressure variation that does not exceed 20% of said average pressure;
detecting a temporal response of the embryo or oocyte to the substantially constant pressure using a microscope, said temporal response comprising aspiration depths of the embryo or oocyte as a function of time at said substantially constant pressure; and
deriving measurements for one or more parameters from the temporal response, the measurements being indicative of viability.
2. The method of claim 1 , wherein the one or more parameters comprise at least one of speed and depth of inflation.
3. The method of claim 2 , further comprising comparing the measurements for the embryo or oocyte to measurements for a reference embryo or oocyte.
4. The method of claim 3 , wherein the reference embryo or oocyte is a virtual embryo or oocyte generated by pooling measurement data from a reference population of embryos or oocytes, or an embryo or oocyte from the same mammalian donor as the embryo or oocyte being measured.
5. The method of claim 4 , further comprising determining that the embryo is more likely viable, or the oocyte is more likely to generate a viable embryo, than the reference embryo or oocyte, if a measured speed is lower than that of the reference embryo or oocyte, or if a measured depth is shorter than that of the reference embryo or oocyte.
6. The method of claim 2 , wherein the speed comprises an initial inflation speed defined as a ratio of depth of inflation to length of time starting from a beginning of application of the negative pressure.
7. The method of claim 6 , wherein the length of time is less than 0.5 second.
8. The method of claim 2 , wherein the depth of inflation is during a period after an initial inflation slows down and substantially stabilizes.
9. The method of claim 8 , wherein the period starts from at least 0.5 second after initiation of the negative pressure and is no more than 5 seconds after initiation of the negative pressure.
10. The method of claim 2 , wherein the embryo is at or less than 1 day old following fertilization.
11. The method of claim 2 , wherein the embryo is a human embryo.
12. The method of claim 11 , wherein the portion of the surface of the embryo is from 35 μm to 65 μm in diameter.
13. The method of claim 11 , wherein the pressure is from −0.35 psi to −0.75 psi.
14. The method of claim 1 , wherein the portion of the surface of the embryo or oocyte is from 25 μm to 100 μm in diameter.
15. A method for selecting a human embryo from a plurality of human embryos for transfer to a human subject, comprising:
applying a negative and substantially constant pressure using a pipette on a portion of each human embryo, said substantially constant pressure having an average pressure of −0.3 psi to −1 psi and a maximum pressure variation that does not exceed 20% of said average pressure;
detecting a temporal response of each human embryo to the substantially constant pressure using a microscope, said temporal response comprising aspiration depths of the embryo or oocyte as a function of time at said substantially constant pressure;
deriving measurements for one or more parameters from the temporal response, the measurements being indicative of viability; and
selecting from the plurality of human embryos for the transfer based on the measurements to identify a selected human embryo.
16. The method of claim 15 , wherein the one or more parameters comprise at least one of speed and depth of inflation.
17. The method of claim 15 , further comprising transferring the selected human embryo to the human subject.
18. A method for tuning an embryo, comprising applying a negative, substantially constant pressure using a pipette on a portion of a surface of the embryo to inflate the embryo at the portion but not to damage the embryo, wherein the embryo is a human embryo that is less than 3 days old following fertilization, the portion of the surface of the embryo is from 40 um to 60 um, the substantially constant pressure has an average pressure from −0.3 psi to −0.5 psi and a maximum pressure variation that does not exceed 20% of the average pressure.