Name: reprogramming mature cells into stem cells
Uploaded: 2019-03-11T09:21:22.000Z
Duration: 1 min 13 s
Channel: JoVE

תאי גזע iPSCs פלוריפוטנטיים מושרים, הם תאים בוגרים וממוינים, כגון תאי עור, אשר מתוכנתים מחדש במעבדה לדמות תאי גזע עובריים לא ממוינים. כלומר, הם מתחלקים ופלוריפוטנטיים, מסוגלים לייצר כל סוג תא בגוף. לדוגמה, תאי רשתית, שעשויים לשמש להחלפת רקמת רשתית פגומה.כדי ליצור iPSCs, תאים בוגרים, כמו פיברובלסטים של עור, נלקחים ממטופל ומוכנסים לתרבית. בדרך כלל, גנים עבור גורמי שעתוק מועברים על ידי וקטורים ויראליים לתוך גרעיני התאים, שם הם משולבים לתוך הגנום. גורמי השעתוק מפעילים בתורם את הגנים המבוטאים על ידי תאי גזע עובריים, שהופכים בכך שוב ללא ממוינים וחוזרים למצבם הפלוריפוטנטי.התאים יכולים כעת להתחלק וניתנים להכוונה לייצר סוג תא מסוים בתרבית. לאחר מכן, ניתן לשתול את התאים החדשים ב‫חזרה במטופל כדי לטפל בנזק או במחלה עם סיכון מינימלי לדחייה, כי הם מיוצרים מתאי המטופל עצמו.

Hamazaki, Takashi, Nihal El Rouby, Natalie C. Fredette, Katherine E. Santostefano, ו Naohiro Terada. "סקירה תמציתית: מחקר תאי גזע פלוריפוטנטיים מושרה בעידן הרפואה המדויקת." תאי גזע (דייטון, אוהיו) 35, מס '3 (מרץ 2017): 545–50. [<a href="https://doi.org/10.1002/stem.2570" target="__blank">Source</a>].

תאי גזע מושרים

Induced Pluripotent Stem Cells

<div style="direction:rtl">תאי גזע הם תאים לא מובחנים שמתחלקים ומייצרים סוגים שונים של תאים. בדרך כלל, תאים שהתמיינו לסוג תא מסוים הם פוסט-מיטוטיים כלומר, הם כבר לא מתחלקים. עם זאת, מדענים מצאו דרך לתכנת מחדש את התאים הבוגרים הללו, כך שהם יתבדו ויחזרו למצב לא מתמחה, מתרבה. תאים אלה הם גם פלוריפוטנטיים כמו תאי גזע עובריים המסוגלים לייצר את כל סוגי התאים ולכן נקראים תאי גזע פלוריפוטנטיים (iPSCs). iPSCs הם בעלי ערך רב ברפואה, מכיוון שחולה הזקוק לסוג תאים מסוים, למשל, מישהו עם רשתית פגומה עקב ניוון מקולרי יכול לקבל השתלה של התאים הנדרשים, שנוצרו מסוג תאים אחר בגופו. דבר זה נקרא השתלה אוטולוגית, והיא מפחיתה את הסיכון לדחיית השתל שעלולה להתרחש כאשר רקמות מושתלות בין אנשים. <h4>התהליך</h4> כדי ליצור iPSCs, גדלים בתרבית תאים בוגרים כגון פיברובלסטים בעור או תאי דם מאדם. לאחר מכן, גנים עבור גורמי שעתוק מרובים מועברים לתאים באמצעות וקטור ויראלי, וחלבוני גורמי השעתוק באים לידי ביטוי באמצעות מכונות התא. לאחר מכן גורמי השעתוק מפעילים גנים רבים אחרים המתבטאים על ידי תאי גזע עובריים, ומחזירים את התאים למצב של תאי שגשוג, תאים לא ממוינים, ותאים פלוריפוטנטיים. עדיין נחקר האם iPSCs באמת שוות ערך לתאי גזע עובריים, אך נראה שהם דומים ויכולים לייצר תאים מכל שלוש שכבות הנבט של הגוף. כמו סוגים אחרים של תאי גזע, מדענים לומדים כיצד לקדם את ההתמיינות של סוגי תאים ספציפיים מ-iPSCs ביעילות, כך שניתן לייצר את סוגי התאים הדרושים בכמויות נאותות. <h4>ניסויים קליניים מוקדמים</h4> הניסוי הקליני הראשון השתיל תאי רשתית שמקורם ב-iPSCs בחולים עם ניוון מקולרי הקשור לגיל. מאז, אושרו מספר ניסויים קליניים של iPSC לטיפול במחלת פרקינסון, מחלות לב ופציעות חוט השדרה. תאים שנלקחו מחולים והופכים ל-iPSC משמשים גם לחקר המחלות שלהם במעבדה. באופן כללי, iPSCs מספקים מקור נוסף לתאי גזע למחקר מדעי.</div>

תאי גזע הם תאים לא ממוינים שמתחלקים ומייצרים סוגים שונים של תאים. בדרך כלל, תאים שהתמיינו לתא מסוים ...

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reprogramming mature cells into stem cells

Reprogramming mature cells into stem cells lets scientists turn specialized cells back into an unspecialized state. These cells are called induced pluripotent stem cells, or iPSCs. Like embryonic stem cells, iPSCs are pluripotent, which means they can form all cell types.

To make iPSCs, researchers start with mature cells such as skin fibroblasts or blood cells. The cells are grown in culture, and genes for several transcription factors are delivered with a viral vector. The cells then make those transcription factor proteins, which switch on other genes that are active in embryonic stem cells and return the cells to a proliferative, undifferentiated, and pluripotent state.

iPSCs may be useful in medicine because they can come from a patient’s own body. For example, cells needed to repair a damaged retina in age-related macular degeneration could be made from that same patient’s cells. This autologous transplantation lowers the risk of transplant rejection that can happen when tissue is moved between different people.

Scientists are still studying whether iPSCs are truly equivalent to embryonic stem cells, but they appear to be similar and can produce cells from all three germ layers. Researchers are also working on ways to direct iPSCs to become specific cell types in efficient amounts. Early clinical trials have used iPSC-derived retinal cells for macular degeneration, and other trials have been approved for Parkinson’s disease, heart disease, and spinal cord injury. Patient cells turned into iPSCs are also helping scientists study disease in the lab.

Reprogramming Mature Cells into Stem Cells

reprogramming-mature-cells-into-stem-cells

what is genetic engineering?

How Scientists Edit DNA for New Traits

Genetic engineering changes an organism’s DNA to add useful traits. Scientists use it in bacteria, plants, animals, and even viruses for research, medicine, agriculture, and industry. It can bring major benefits, but it also raises ethical concerns about humans and the food supply. This work is possible because DNA has the same basic structure and genetic code across life. That shared code lets scientists modify DNA in several ways. One method is CRISPR/Cas9, often called molecular scissors,...

dna isolation

Steps in DNA Extraction

DNA extraction is the process of removing and purifying DNA from cells. It is used in many biotechnology and research applications, including molecular cloning. The main goal is to free DNA from the cell and prepare it for later study or use. The first step is cell lysis, which means breaking cells open. Researchers may use a homogenizer, sonicator, or bead beater to physically lyse the cells. They also often add detergent to chemically disrupt the lipid-based cell membranes. This helps...

recombinant dna technology

Recombinant DNA in Cloning and GMOs

Recombinant DNA is made by joining DNA from different sources in the lab. Scientists often use it to clone genes and study them in cells that are easy to handle, such as bacteria. Organisms that carry recombinant DNA are called genetically modified organisms, or GMOs. This technology gives scientists new tools for research, medicine, and agriculture. To build recombinant DNA, researchers place a gene of interest into a vector, which is a DNA carrier that moves foreign DNA into a host cell. The...

PCR Cycle for DNA Amplification

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complementary dna

From mRNA to cDNA for Gene Studies

Complementary DNA, or cDNA, is made from messenger RNA (mRNA) so scientists can study which genes are active in cells and tissues. Only genes that are transcribed into mRNA are expressed. By extracting mRNA from cells, researchers can compare gene expression across samples. cDNA is produced by reverse transcription. This process copies mRNA into DNA, which is useful because mRNA does not contain introns, or non-coding regions, and other regulatory sequences. As a result, cDNA can help...

antibiotic selection

Antibiotic Resistance in Cloning

Antibiotic resistance genes help scientists find bacteria that took up a plasmid with a gene of interest. In genetic engineering, this resistance is used as a marker, not just as a medical concern. The same process also connects to the growing problem of resistant bacteria in the real world. Antibiotics, such as penicillin, stop bacterial growth or kill bacteria. When bacteria naturally have, or are engineered to carry, an antibiotic resistance gene, the antibiotic no longer works on them.

transgenic organisms

Creating Transgenic Plants and Animals

Transgenic organisms are genetically engineered to carry a transgene, which is a gene from a different species, in their genome. The inserted gene may be a new gene for that organism or a different version of one it already has. Scientists usually make transgenes with recombinant DNA and DNA cloning methods. Researchers use transgenic bacteria, plants, and animals to answer biological questions and to build useful tools. To make a transgenic organism, they first choose a transgenesis method,...

in-vitro mutagenesis (gene knockouts)

Knockout Mice and Gene Replacement

Knockout mice help researchers study gene function by showing what happens when a gene is turned off. These engineered animals are also useful for modeling human diseases such as cancer, Parkinson’s disease, and diabetes. A specific gene can be targeted by using a targeting vector, which is a piece of engineered DNA that replaces the normal gene and inactivates it. The vector has matching DNA sequences on both ends. These homologous sequences let the vector swap in for the target gene through...

crispr

CRISPR-Cas9 Gene Editing in Action

CRISPR-Cas9 is a genome editing tool that lets scientists change DNA at a specific location. It can add, remove, or rearrange genetic material. Researchers study it because it may help treat genetic disorders such as hemophilia and sickle cell anemia. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats, and Cas9 is a CRISPR-associated protein 9. The basic system includes a Cas9 endonuclease, which is an enzyme that cuts DNA, and a small RNA that guides Cas9 to the...

gene therapy

Gene Delivery for Serious Diseases

Gene therapy is a technique used to treat serious disease by adding a gene to a person’s cells. The added gene may be a healthy copy of a mutated gene. It may also be a different gene that inactivates or compensates for the disease-causing gene. One example is severe combined immunodeficiency, or SCID, caused by a mutation in the gene for adenosine deaminase. In that case, a working copy of the gene can be inserted so the patient’s cells make the enzyme again. This can cure the disease in some...

embryonic stem cells

How Embryonic Stem Cells Become Specialized

Embryonic stem cells are pluripotent cells that have not yet specialized. Pluripotent means they can give rise to many different cell types in the body. Because of this, they are useful in science and medicine for making cells needed in research or for replacing cells lost to damage or disease. These cells come from the inner cell mass of a blastocyst, which is an early embryo about 3 to 5 days after fertilization in humans. At this stage, the embryo has not yet implanted in the uterus. Human...

adult stem cells

Adult Stem Cells in the Small Intestine

Adult stem cells help maintain tissues by replacing old or damaged cells. These undifferentiated cells divide to make more stem cells or progenitor cells, which then become mature, specialized cells. Small groups of adult stem cells are found in many tissues, including the bone marrow, brain, skin, and gut. The small intestine shows this process clearly. Its lining, called the epithelium, is renewed continuously by adult stem cells. It is also the fastest replaced tissue in the human body,...

induced pluripotent stem cells

Reprogramming mature cells into stem cells lets scientists turn specialized cells back into an unspecialized state. These cells are called induced pluripotent stem cells, or iPSCs. Like embryonic stem cells, iPSCs are pluripotent, which means they can form all cell types. To make iPSCs, researchers start with mature cells such as skin fibroblasts or blood cells. The cells are grown in culture, and genes for several transcription factors are delivered with a viral vector. The cells then make...

reproductive cloning

Cloning Animals with SCNT

Reproductive cloning can produce a genetically identical copy of an entire organism. In adult animals, this is usually done with somatic cell nuclear transfer, or SCNT. Another way clones can form is by splitting an early embryo, which is similar to how identical twins arise naturally. In SCNT, an egg cell is taken from an animal and its nucleus is removed. This creates an enucleated egg. A somatic cell, which is any body cell that is not a sex cell, is then taken from the animal to be cloned.

genomics

Genomics and DNA Sequencing

Genomics studies the full set of genetic material in an organism. In humans, that genome includes the DNA carried in 23 pairs of chromosomes in the nucleus, along with mitochondrial DNA. Genomics looks at both coding DNA and non-coding DNA, which helps scientists study how living things are built and how they differ. This field is useful in many areas of biology and medicine. Scientists use genomics to build phylogenetic trees, improve crop productivity and sustainability, help with criminal...

key terms and concepts

Learn how mature cells are reprogrammed into induced pluripotent stem cells, why iPSCs matter for transplants, and how they are used in research and clinical trials.

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Reprogramming Mature Cells into Stem Cells

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