EAST 501 Lecture Notes - Lecture 5: Oogonial Stem Cells, Female Infertility, Heteroplasmy
21 Jun 2018
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Jan 19th – Lec 5 Bernard
Female infertility: Oogonial Stem Cells & AUGMENT
OUTLINE
1. Rationale for mitochondrial transfer in ICSI
2. AUGMENT
3. Are there adult OSCs? Are there oogonial stem cells and if there aren’t where are the mitochondrial coming
from?
4. Challenges to ARTs that depend on OSCs
AUTOLOGOUS GERMLINE MITOCHONDRIAL ENERGY TRANSFER (AUGMENT)
-OSCs: oogonial stem cells
-this is a modification to ICSI
-isolated OSC mitochondria are injection into the oocyte (mito derived from stem cells that could give rise to new
eggs)
IVF/ICSI SUCCESS RATES ARE PARTICULARLY LOW IN OLDER WOMEN (>40Y)
-live birth rate much lower for women 40-42 using their own oocytes compared to aged <40y
oquestion: is there anything that we can do to increase the success rates of the older women?
oboth egg quality and quantity diminish with age
-for those using donor oocytes, live birth rate does not decrease with the women age (carrying baby
EGG QUALITY AND QUALITY DECREASE WITH AGE
-driving forces are that both the egg quality and the quantity diminish with age
ogradual loss of follicles and thereby germ cells with age
othere is a marked increase in aneuploidy with age and chromosome segregation issues
-there is an inflection point a bit below 40 where the loss of follicles is accelerated
SUCCESSFUL PREGNANCY AND LIVE BIRTH ACHIEVED WITH OOPLASM TRANSFER IN ICSI
-39 y woman, 6.5y infertility, four failed IVF cycles
-long protocol COH in patient and 27yo donor (also used the COH long protocol for the donor)
-20 poor quality oocytes from women, 12 normal appearing oocytes from donor then did ICSI with the patient’s
partner’s sperm
-sperm with (14) or without (6) donor ooplasm (cytoplasm from the donor) injected into patients oocytes
-four out of the 14 embryos derived from ooplasm-treated eggs transferred (ooplasm from the donor in all
these cases were injected along with the sperm)
-singleton pregnancy, birth of healthy girl
-inspired by similar results in animal studies something in the cytoplasm was seemingly improving success in
ICSI
SEVERAL CHILDREN BORN FOLLOWING OOPLASM TRANSFER IN ICSI
-all in women unsuccessful before with the AUGMENT they were able to get take home babies
CONCERNS OVER HETEROPLASMY CAUSED FDA TO INTERVENE
-after the AUGMENT they did a blood test of the babies what they found was heteroplasm mitochondria
derived from the mother and the donor
omost of the DNA from the mother, but a bit also from the donor
-2 children conceived with ooplasm transfer possessed mitochondria from mother and donor (3 parent offspring)
othey found evidence that the mitochondria was derived from the mother and the donor
nuclear DNA from the mother and father, mitochondria DNA from the donor
owe cannot have 3 parent children in NA, but it is okay in the UK
find more resources at oneclass.com
find more resources at oneclass.com
Jan 19th – Lec 5 Bernard
Female infertility: Oogonial Stem Cells & AUGMENT
othey found that most of the DNA was from the mother, but there was also from the donor = the
offspring has 3 genetic parents
-FDA informed clinics that investigational new drug (IND) applications required before treating more patients
(July 2001) normal drug approval process
MITOCHONDRIA FROM DONOR PERSIST FOLLOWING INJECTION INTO RECIPIENT OOCYTES
-took a stain that stains the mitochondria (miotracer)
oafter 10mins could see the stain
othere is a persistence of the mitochondria after 24hours in 3 pronuclear zygotes which raised the
possibility that maybe if there is a beneficial benefit of the ooplasm, then maybe it is the mitochondria,
because they actually persist and are an energy source
MITOCHONDRIAL DNA CONTENT IS LOWER IN OOCYTES OF OLDER WOMEN – all correlational evidence
-there is correlative evidence that there is a decline in mitochondria as women age
othere is a significant different in women older 40 vs. under 40 (although there is an overlap)
FERTILIZATION OUTOCME IS RELATED TO MITOCHONDRIAL DNA CONTENT
-they quantified mitochondria DNA content from eggs that were successfully and unsuccessfully fertilized
-the amount and quality of mitochondrial may affect the implantation success
-they looked at the mtDNA content of eggs that were successfully fertilized compared to those that weren’t
o~250,000 copies of mtDNA in the fertilized eggs compared to ~163k in the unfertilized eggs
othis showed a correlation between fertilizability and mtDNA content
oamong the eggs that were fertilized:
arrested at 2 pro-nuclei mean: 165k mtDNA copies
abnormally fertilized at 3 pro-nuclei stage mean: 306k mtDNA copies
normally fertilized mean: 333k mtDNA copies
-as you process from normally fertilized to the arrested there is indeed a decrease in the mtDNA quantity;
however it is important to note that there is a lot of variability present so maybe there is not a lot of weight to
this
otake away: the amount and quality of mtDNA MIGHT impacted fertilization and implantation potential
THE BASIC STEPS OF AUGEMENT
1. Egg precursor cells taken from small biopsy of ovary (laproscopic surgery where they take part of the ovarian
cortex) part of the tissue is enzymatically degraded
2. the presumptive OSCs are purified and they are grown in culture (they are stem cells and will continue to divide
in culture) and frozen for storage
3. Mitochondria from precursor cells are purified and injected with sperm into IVF egg
-Advantages over other transfer methods:
oMitochondria alone (just transferring this part of the cytoplasm)
oAutologous – the mito come from the women into which you are injecting no heteroplasmy issue
oderived from cells that give rise to oocytes they are in the same lineage
o higher quality mitochondria than in oocytes or somatic cells
there is evidence that mitochondria DNA becomes damaged with time (especially in somatic
cells)
according to the company the mtDNA is superior in the Oogonial stem cells compared to the
mtDNA in a somatic cell
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Are there oogonial stem cells and if there aren"t where are the mitochondrial coming from: challenges to arts that depend on oscs. Oscs: oogonial stem cells this is a modification to icsi isolated osc mitochondria are injection into the oocyte (mito derived from stem cells that could give rise to new eggs) Successful pregnancy and live birth achieved with ooplasm transfer in icsi. 39 y woman, 6. 5y infertility, four failed ivf cycles long protocol coh in patient and 27yo donor (also used the coh long protocol for the donor) Several children born following ooplasm transfer in icsi all in women unsuccessful before with the augment they were able to get take home babies. Bernard: they found that most of the dna was from the mother, but there was also from the donor = the offspring has 3 genetic parents. Fda informed clinics that investigational new drug (ind) applications required before treating more patients (july 2001) normal drug approval process.
