Stem cells and cell differentiation Flashcards

Question

Shinya Yamanaka

Answer 1

Given the Nobel prize in 2012 for his research on induced pluripotent stem (IPS) cells. iPS reprogramming factors are introduced to adult cells, creating IPS cells. IPS cells are embryonic stem cell-like cells that can differentiate into other types of cells.

Answer 2

Stimulus triggered acquisition of pluripotency cells. In this study, cells were isolated and acid was added to shrink the cells and "shock" them to revert them to a stem cell-like state. These findings were reported in 2014 but were later retracted as the research was fraudulent.

Answer 3

This is problem with stem cells- they can spontaneously fuse with each other, forming a tetraploid cell (could generate cancer stem cells). When injected into patients mechanical stress can cause fusion

Answer 4

The norms of conduct. Relatively term and country dependent

Answer 5

The production of embryonic stem cells for the use in replacing or repairing damaged tissue or organs. The embryo is developed under laboratory conditions and treats diseases like diabetes and Alzheimer's Disease. An egg's nucleus is removed and a diploid nucleus from a body cell is transferred into the egg to create an embryo that stem cells can be harvested from.

Answer 6

The deliberate production of genetically identical individuals, each newly produced individual is a clone of the individual. The embryo that is created is developed under uterine conditions. A diploid nucleus is still inserted into an enucleated egg, but the egg is implanted into a surrogate mother (like a sheep), and the clone will be born. This method is used to harvest stem cells that can be used to study embryonic development.

Answer 7

Severe combined immunodeficiency- have no B and T cells and thus have a compromised immune system. Are used for determining if an injected candidate stem cell can differentiate in vivo into a multitude of tissue types in vivo. Are also used to determine if a candidate human cancer cell can generate tumors in vivo

Answer 8

1. Somatic Cell Nuclear Transfer (SCNT) 2. Parthenogenesis (hPSCs) 3. Induced Pluripotent Stem Cells (iPSCs)

Answer 9

A technique in which the nucleus (DNA) of a somatic cell is transferred into an enucleated metaphase-II oocyte for the generation of a new individual, genetically identical to the somatic cell donor. This has been used for reproductive cloning, like when Dolly the sheep was cloned

Answer 10

Sir Ian Wilmut cloned Dolly in 1996 but John Gurdon did it with frogs in 1960 and finally was awarded a Nobel Prize in 2012. First pet clone was a cat- “Little Nicky” – 2004

Answer 11

1000s SCNT are required for one implantable embryo. This is still the problem today- as a result many SCNT researchers left the field. But some are still attempting human SCNT designed for therapeutic cloning because hESCs could serve as an autograft

Answer 12

Take out a somatic cell (the person’s own cell). Use SCNT and introduce the cells back into the person.

Answer 13

Dolly was born at Edinburgh University in 1996, she was euthanized at age 6 due to lung disease and advanced arthritis. But other identical clones, now 9 years old, from the same SCNT (Debbie, Denise, Diana and Daisy) are fine. SCNT showed that a SCNT nucleus could create an entire functioning animal due to cytoplasmic factors in the egg

Answer 14

Monkeys were cloned in 2018 using SCNT

Answer 15

A type of asexual reproduction- development of an embryo from an unfertilized egg cell (no sperm). May be a potential source of embryonic stem cells that may avoid some of the political and ethical concerns surrounding embryonic stem cells.

Answer 16

Artificial parthenogenesis was first shown in 1913 by Loeb using two experimental systems. Unfertilized sea urchin eggs were induced to undergo parthenogenesis by changing the osmolarity of the surrounding medium. Unfertilized starfish eggs could do the same using dilute acid

Answer 17

Also called Parthenotes. Derived from the inner cell mass of blastocysts obtained from unfertilized oocytes that have been activated using parthenogenesis. These cells demonstrate characteristics typical for human embryonic stem cells (hESC), including extensive self-renewal and in vivo as well as in vitro differentiation into cells of all three germ layers.

Answer 18

According to ISCO- only 200 to 300 eggs would be required to generate hPSCs that could match anyone in the world

Answer 19

1. All alleles will be homozygous because of no sperm 2. Not FDA approved in US 3. Is it ethical to create a human embryo?

Answer 20

Patient cells are harvested and made into induced pluripotent stem cells. A genetic mutation can be targeted and repaired. Then, the now healthy stem cells undergo in vitro differentiation. Healthy, genetically matched cells are transplanted back into the patient.

Answer 21

Once patient IPS cells are generated, they will undergo in vitro differentiation. The affected cells are then screened for therapeutic compounds. The patient can be treated with whatever compound is found to be effective.

Answer 22

Two groups have shown that somatic human cells can be converted to true stem cells (iPSCs) with only 4 additional genes. Shinya Yamanaka of Kyoto University in Japan used a retrovirus to ferry into adult human fibroblasts OCT3/4, SOX2, KLF4 and c-MYC genes. Sources were skin cells from 36 year old female and 69 year old man. Also, James Thomson of the University of Wisconsin (pioneer in hESCs) used OCT3/4, SOX2, NANOG and LIN28 genes

Answer 23

There are activate genes that code for self renewal and pluripotency. There are also repress genes that induce specific differentiation pathways. This information comes from research on SCNT

Answer 24

Reverse transcription PCR. Studies true differentiation in culture as revealed by appropriate markers

Answer 25

Is a teratoma generated by iPSC injection? The iPS cells form teratomas in mice – a non malignant mass of differentiated cells derived from iPSCs

Answer 26

A malignant teratoma that originates from embryonic cells or stem cells. Can iPSCs and hESCs do this too? In the US, iPSCs are not in clinical trials like human embryonic stem cells

Answer 27

Sells iPSCs

Answer 28

1. Basic research on differentiation 2. Can make patient specific cells of individuals carrying genetic defects 3. Source of cells in the future for stem cell therapy. Not yet FDA approved but Cynata Therapeutics (Australia) just completed first clinical trials in using iPSCs. 4. Will be useful in tissue engineering

Answer 29

Scientists at the Babraham Institute have developed a method to “time jump” human skin cells (fibroblasts) by 30 years turning back the aging clock. They measured telomere attrition, genetic instability, epigenetic and transcriptional alterations and the accumulation of misfolded proteins – all accepted markers of cell aging. They used the same 4 Yamanaka reprogramming factors but rather than waiting the required 50 days culture time to generate iPSCs they waited just 13 days and the cell has now reversed its aging process by 30 years

Answer 30

Researchers at Salk lab used a short-term (one day, not 50) Yamanaka factor protocol to partially reprogram mice liver tissue. Liver exhibited improved regeneration and younger characteristics. But, they didn’t generate teratomas or other cancers which is typical of a standard longer Yamanaka procedure. Currently trying to understand the molecular basis of this “rejuvenation”

Answer 31

1. Could be used for an autologous transplant if FDA approved 2. No US federal laws banning therapeutic or reproductive cloning but some states forbid it. 3. But is it ethical? A “human embryo” is being created.

Answer 32

1. Can match to a world population – only 300 eggs required 2. But all alleles are homozygous, not heterozygous 3. Allogeneic, not autologous like SCNT unless female donated egg 4. But is it ethical? A “human embryo” is being created.

Answer 33

1. No “human embryo” created as in previous two 2. Can be autologous or allogeneic 3. But potential for teratocarcinomas 4. More pluripotent than fat (adipose)-derived adult mesenchymal stem cells and easier to procure

Answer 34

1. Tumorigenicity 2. Immunogenicity 3. Inappropriate differentiation

Answer 35

Stem cells have long telomeres and can divide many more times than normal cells. (Telomeres = “mitotic clock”). Propensity to form tumors and teratomas. One clinical trial started in Japan overseen by the RIKEN Institute (later) was stopped after only one patient due to this concern

Answer 36

Propensity to trigger immune response. The more frequent the stem cell injections the higher the chance of immune rejection complications that could include anaphylaxis. Autologous as well as allogeneic uses can launch an immune response

Answer 37

Risk of stem cells differentiating into cells that were not intended and not native to target organ. Example- A woman injected with human mesenchymal stem cells (MSCs) near her eyes ended up with bone tissue growing inside her eyelids

Answer 38

Transplanting neuronal stem cells into damaged or diseased areas of the brain has been touted as a potential therapeutic option, although it has been met with some difficulties. Yet now, investigators at Lund University in Sweden may have just found a path forward for using induced pluripotent stem (iPS) cell-derived cortical neurons for treating stroke-afflicted rats. The approach was able to restore mobility and sensation of touch by reprogramming human skin cells to become nerve cells, which were then transplanted into the rats’ brains

Answer 39

World’s first vascularized human heart with atria and ventricles and patches – heart size of a rabbit heart. It was generated from iPSCs and donor’s own ECM that is processed into a personalized hydrogel making them biocompatible for implantation in the future. Goal is to train them to behave like a real heart. Cardiomyocytes beat but not in a coordinated fashion

Answer 40

An example of a unipotent stem cell. BMT- replacing stem cells to make new blood cells, used to treat blood cancers

Answer 41

Specially bred (transgenic) zebrafish whose hematopoietic stem cells can fluoresce up to 80 different colors so that stem cell fate can be tracked. Multiple copies of genes for red to blue fluorescent proteins are a permanent part of the genome of Zebrabow. Technique is referred to as “fluorescent bar coding”

Answer 42

Cord blood contains hematopoietic stem cells, and cord tissue contains mesenchymal stem cells. It can be stored in case the patient is ever in need of stem cells

Answer 43

Incorporated as a “for profit” organization-donors pay an initial fee and a maintenance fee. Cells not available to the public. Better if there is a genetic disease in the family and multiple members require the cells

Answer 44

Incorporated as a “not for profit” organization. Available to the public through the National Marrow Donor Program through which cord blood is matched

Answer 45

A private cord blood bank

Answer 46

Used to study cell differentiation by Robert Korbis. Translucent- made microscopy easier

Answer 47

1. Easy to grow on agar plates 2. Non pathogenic 3. Translucent – can optically section through organism 4. Stable mutant C. elegans are available for study 5. All cells have been coded and differentiation predicted 6. Cell division or differentiation patterns can be predicted and always follow the same pattern 7. Many genes like the apoptotic genes have mammalian homologs. The apoptotic genes were first identified in C. elegans – excellent model to study apoptosis 8. Comprised of a limited number of cells (about 1000) 9. First microRNA (miRNA) discovered

Answer 48

The ability of cells to reorganize their internal structure, resulting in changes in cell shape and the generation of regions of the plasma membrane with different morphologies and protein and lipid compositions. C.elegans has been used to study the polarization of embryonic axes

Answer 49

Before its first cell division, the C. elegans zygote is asymmetric, and its first division is asymmetric. Cytoplasmic complexes called P granules concentrate in the region of the cell that gives rise to the posterior end of the embryo. To study this, genetic mutations were identified where there was a symmetric first division of a zygote. The P granules were not positioned correctly, so these genes were called partition defective (Par genes). It was found that par proteins are asymmetrically localized by antagonistic interactions.

Answer 50

Researchers can silence a C. elegans gene of interest using one of two methods (double stranded RNA in vitro or in vivo). The C. elegans heterochronic mutant was key to discovering lin-4 RNA- this was the first microRNA ever discovered

Answer 51

Small endogenous RNA molecules that regulate genes

Answer 52

Scientists at the University of Vermont, Tufts University and Harvard University's Wyss Institute for Biologically Inspired Engineering said they have discovered an entirely new form of biological reproduction different from any animal or plant known to science. Frogs have a way of reproducing that they normally use but when you liberate the stem cells from the rest of the embryo and you give them a chance to figure out how to organize in a new environment, not only do they figure out a new way to move, but they also figure out apparently a new way to reproduce by pushing cells together in a clump to make another C-shaped Xenobot