| 1 | Animated biology With arpan | IPSC | Induced Pluripotent Stem Cells Explained in simple terms | Clin... | 7932 | 232 | 29 | 76.2 | positive | 12:50 | Video will talk about induced pluripotent stem cell. Induced pluripotent stem cell is a type of stem cell which is artificially derived from non-pluripotent somatic cell. And this was discovered by Shiniya Yamanaka and his colleagues. So, Shiniya Yamanaka got the Nobel Prize in Medicine and Physiology in 2012. And this is for the discovery of the factors that can convert any cell type into a stem cell. So, these factors or set of transcription factors which are known as Yamanaka factors has the capability to transform somatic cell into IPSCs. So, these transcription factors are opt 4 socks to seamyk and KLE 4. So, the key features of IPSC is they are pluripotent. So, they can give rise to 3 germ layers. They have the capability to form ectoderm mesoderm or even endodermal derivatives. They are self-renewing that means they can proliferate and has the capability to differentiate into specific lineages. Now, let us try to understand how researchers can make the IPSC in the lab. So, obviously, these kind of conversion of any cell into a stem cell requires reprogramming. And this reprogramming can be by integrative methods or via non-integrative methods. In integrative methods which were old school, retroviral or lentriviral vectors were used to give these transcription factors into cells. Now, in non-integrative methods, sendivirus or epizomal plasmids are used. So, problem with integrating method is there is a risk of insertional mutagenesis in that case. In case of non-integral method, it is basically preferred because the chances of incorporating a mutation is less. And it is preferred in clinical settings. So, let us talk about the first experiment that happened. So, there was some mouse fibroblast and there were viral transduction of these factors, oct 4, oct 3 or oct 4, cemic, sox 2 and k-lef 4. Now, after the transfection process, after the transduction process, these transcription factors were misexpressed. They are not supposed to be present in the mouse fibroblast, they are artificially expressed in that cells and eventually the cells get converted. And they converted into something called induced pluripotent stem cells. These stem cells has the capability to generate mesoderm lineage, for example, blood, muscle, etc. It can give rise to a total normal lineage, for example, neuron. It can give rise to endodormal lineage, for example, pancreatic endocrine cells. So, these IPSEs open the door for humongous clinical applications. But question is, how at a fundamental level Yamana ka factor can do these transformation? These transformations are quite difficult, right? To imagine. So, let us try to understand what really happens when Yamana ka factors are added. Inside the cell, the DNA is compacted in form of chromatin. There are many locus which are inaccessible for general transcription factor. And that is why in differentiated cell, other kind of lineage markers are not basically present. So, basically the nucleosome is tightly wrapped around his stone preventing the access to the nucleosome. But Yamana ka factors are very different. They are known as transcription factors which are pioneer transcription factors. So, they can access the chromatin even if the chromatin is condensed. They can latch onto the heterochromatinized regions and eventually open the chromatin region. That lead to transcription of many gene. For example, KLA4, Oct4 and Sox2 give rise to the transcription of Nanog, ESRRB and Indoginus Sox2 and Nanog gene. So, all these locus get opened. Now, overall there is an important process. So, there has to be suppression of the somatic gene and there should be activation of the pluripotency gene network. So, when a somatic cell is getting converted into a IPSE at fundamental level, somatic identity is decreasing over time and the stem cell like identity is gained over time. So, obviously somatic gene regulation networks would basically be down-regulated whereas the stem cell gene modulatory network would be up-regulated and that would be in action. So, question is how suppression of somatic identity happens or activation of pluripotency gene takes place. It turns out factors like KLA4 and CMEK prevents specific fibroplast-specific genes such as coal 1a1, thai1, etc. CMEK on the other hand promote the metabolic or biosynthetic shift that means generally the cells prefer oxidative phosphorylation to generate ATP. But the metabolism now shifted towards glycolysis and CMEK actually up-regulates enzymes and molecules that are required for orchestrating glycolysis, making the cell very much like a stem cell in terms of metabolic needs. Now, all these Yamannaka factors can recruit epigenetic modifiers and many of these epigenetic modifiers are histone-modifying enzyme. For example, it can recruit HAT for adding H3K27 acetylation which would open up certain region of the chromatin. It can also recruit HMTs or histone mithyl transferases. It can give rise to H3K4 tri-methylation which is activitory in nature. Then, DNA-D mithylases can also come into the play and can be recruited by these co-transcription factors. And this would remove mithylation from pleuripotency genes and make this circuit of pleuripotent genes active. They also help to erase repressive marks. So, all these things lead to a dynamic shift into the chromatin architecture. In short, the chromatin of that somatic cell eventually becomes more like a stem cell chromatin. And that lead to the production of genes and machineries that are important for maintaining pleuripotency or a stem cell like state. So, it all boils down into the chromatin and how Yamannaka factors can alter the chromatin architecture. Here are the quick discoveries that really change the field of stem cells. So, first embryonic stem cell was actually discovered in 1998. From that time, one of the big shifts was 2027. So, in 2007, what happens is Yamannaka and Takahashi actually found out that one can use these four factors to convert any cell into a stem cell. Though they got them Nobel Prize in 2012, this was a turning point. By 2010, the first clinical trial of stem cell therapy took place. By 2017, IPSE derived retinal cells were used to treat macular degeneration. So, these are the landmark discovery in clinical perspective. But what are the clinical applications of IPSEs? Let us devote some time on that. So, first, IPSEs can be made from any patients to understand the disease pathology. IPSEs can be used for gene therapy, we just heard about the macular degeneration treatment. IPSEs can be used from the patient for grafts. For example, there is a third degree burn, there is a skin graft required, patient's own cell can be converted into skin cell and can be used as a graft. And lastly, it can be used for precision medicine and it can be used for screening drugs and testing efficacy of the drug. And it kind of creates a tailored treatment strategy. So, macular degeneration is a situation where the central part of the retina, which is known as macula, is getting affected. And it generally happens in the old population. In 2017, the first IPSE derived retinal cells were actually transplanted into the patients with macular degeneration. And this is led by Masaut Akahashi, a pioneering ophthalmologist and a clinical stem cell researcher. She took skin biopsies from the AMD patients, converted them into IPSEs using the Yamana ka factor. And eventually, she grew RPE or retinal pigmented epithelium cells from these IPSEs, because IPSEs has the capability to grow any part of these different three different lineages. And these RPEs were injected into the retina of an patient. And guess what? The patient was actually cured. There are other applications of stem cells and stem cell therapies. For example, a patient is facing a third degree burn. So, a graft can be added into that region. But many of the cases, graft is rejected. Recovery happens when their grafting is proper. So, in order to avoid the immune circumstances, one can literally take the skin cell from the patients and create IPSEs and make artificially a layer of monolayer of skin cells. And artificial skin can be grown in the lab. And ultimately, it can be grafted. In that way, the own skin graft would not be rejected. Now, there are other applications of stem cells. For example, studying the human brain. A developing human brain is very difficult to study. Scientists use monkey and mouse brain to understand what really goes wrong in human brain and how human brain develops. Human brain develop is challenging because this is not possible to access the human embryo and manipulate the human embryo in the mother's womb. So, scientists have discovered something called brain organoids. And these can be made from the IPSE cells. So, IPSE can be converted into brain-like structures known as organoids. And this has been used to uncover many diseases. In the lab, basically, IPSEs would be dissociated and aggregate would be formed known as embryoid bodies. These embryoid bodies can be guided through morphogens to differentiate into specific lineages and an organoid would be formed. Using this strategy, scientists like Maddling Lancaster found out what goes wrong in the patients with microcephaline. So, skin cells from microcephaline patients and a typical individual was taken. And it was found out that the brain organoids develop differently. In the patients with microcephaline. And this was one of the landmark discovery which used the IPSE technology to understand how brain development goes wrong in many diseases. So, overall, we looked at the induced pluripotent stem cell and its application in medicine and biology. So, I hope you like this video. If you like this video, give it a good thumbs up. Don't forget to like, share and subscribe. See you in the next video. Bye. | ↗ |
| 2 | Animated biology With arpan | iPSCs: Turning Any Cell into stem Cells. But how? #animated_biology # ... | 9799 | 268 | 4 | 65.2 | positive | 1:52 | IPSCs are induced pluripotent stem cell grown in the lab and these IPSCs are derived from any somatic cell like a skin cell. There are four magic factors known as Yamanaka factor which can convert any cell into IPSCs and this is the Nobel-winning discovery by Shinya Yamanaka. In this experiment Shinya Yamanaka misexpressed four transcription factor, O3, Cemic, Sox2 and KLE4 in a mouse fibroblast cell and that got converted into a cell type which is very similar to a stem cell. It can now give rise to cells of mesodermal lineage endoderm or ectodermal lineage. These are IPSCs but how does Yamanaka factor work? Any somatic cell has its specific gene expression program. When these transcription factors are misexpressed, these gene expression program has to be shut down and eventually stem cell like gene expression network or modules would be upregulated and act in the cells to make them stem cell like. IPSCs has multiple applications. In 2017 first time IPSCs was used for the treatment of macular degeneration. This was led by the work of Dr. Masau Takahashi. She took cells from AMD patients converted them into induced pluripotent stem cells in the lab. From the stem cells specific differentiation protocol converted these cells into retinal pigmented epithelium and that was injected into the retina of AMD patients which lead to a partial cure. Now IPSC has huge potential in terms of clinical application. So what are the clinical application of IPSCs? Want to know more? You have to watch the full video! | ↗ |