Lecture 21 Flashcards
What are treatments for cancer?
- Radiation
- Surgery
- Chemotherapy
How can radiation affect people?
- Total body or cranial radiation causes hormonal changes in the brain that impact reproductive function.
- Total body or pelvic radiation can affect ovarian follicles and the uterus or spermatogenesis and damage to the germinal epithelium.
How can surgery affect people?
Can impact fertility by either removal of reproductive organs or by loss of vasculature to the reproductive organs.
How can chemotherapy affect people?
The drugs may damage eggs or rapidly deplete the population of dividing spermatogonia found in the germinal epithelium.
What are the clinical fertility preservation options for women?
- Pelvic shielding - to protect one or both ovaries during radiation
- Ovarian transposition - ovaries are moved away from the radiation field
- Embryo banking - Eggs are removed and fertilized for cryopreservation
- Eggs banking - Eggs are removed for cryopreservation without fertilization
- Gonadal suppression - co-administration of a GnRH agonist with chemotherapy may have a protective effect on the ovary
- Ovarian tissue cryopreservation and transplantation - Small pieces of the ovarian tissue are removed and frozen, transplantation may be possible after cancer therapy to restore endocrine function and/or fertility
- In vitro maturation - Immature eggs are removed from the ovary and matured in a laboratory
What are the clinical fertility preservation options?
- Testis shielding - protects the testes during radiation therapy
- Sperm banking - Mature sperm are obtained and frozen via masturbation or otherforms of achieving ejaculation
- Sperm extraction - sperm cells can be extracted from the testes or epididymis surgically and frozen
- Testicular tissue cryopreservation - a small piece of the testis is surgically removed and frozen for possible use in a future treatment
What is the process of how CRISPR works?
- A PAM sequence is found by the guide RNA after being programmed to recognize the sequences (This is a Cas9 RNA)
- The DNA sequence is then cut and replaced with the donor DNA that matches the RNA sequence
Zygote Microinjection of gRNA and Cas9
- Used in sheep
- Often used multiple gRNA
What is the advantage of zygote microinjection of gRNA and Cas9?
- SImpler approach
What are the disadvantages of zygote microinjection of gRNA and Cas9?
- Zygote/Embryo/Fetus survival is low
- Chimeric mutations and cell population
- Likely more “off-target” mutations
- Requires subsequent generations to establish a “line”
Perivitelline Space microinjection of Zygotes
Injection of Adenovirus (AV), Adeno-Associated Virus (AAV) or Lentivirus (LV)
What are the advantages to perivitelline space microinjection of zygotes?
- All resulting cells are likely to exhibit a mutation
- Straight forward approach and more efficient targeting
- AV and AAV are transient, so Cas9 not continuously expressed
What are the disadvantages to perivitelline space microinjection of zygotes?
- Specific mutations may vary
- “Off-target” mutations may result
- Zygote/Embryo/Fetus survival fairly low
What are the advantages to Somatic Cell Nuclear Transfer (SCNT) and CRISPR?
- Validate nature of mutation in donor cells before SCNT
- Verify the lack of “off-target” mutations befre SCNT
- All cells of the resulting pregnancy & offspring should carry exact same mutation
What are the disadvantages of Somatic Cell Nuclear Transfer (SCNT) and CRISPR?
- SCNT has a high rate of pregnancy loss (10-20% success rate)
- Very labor, time and resource consuming
How is tolerance increased via bone marrow transplantation?
- Before transplantation, the recipient undergoes pre-conditioning to make room for the incoming donor bone marrow cells.
- The organ is transplanted at the same time as donor bone marrow.
What is the pre-conditioning requirements of bone mrrow transplantation?
- Recipient is put on immunosuppressive drugs so that the donor bone marrow cells don’t get rejected.
- Donor immune cells are monitored for signs of immunoreactivity against the transplanted organ.
- Only once the tests show no immunoreactivity does the immunosuppressive drugs get reduced.
- Organ function is monitered until complete medication withdrawal is achieved
What are examples of CRISPR being used in farm animals?
- Integrating the polled (hornless) dominant phenotype into the dairy system to avoid having to manually dehorn animas
- Removing the CD163 molecule in pigs in order to resist the PRRS virus.
- Heat resistance
- Increased production traits
- Models for human health and disease using sheep
- Removing boar taint by keeping puberty from occuring and not requiring castration anymore.
- Geep (goat sheep)
- Reviving vulnerable or endangered animal populations using frozen repositories
