Nature's Defenders: Stem Cells as Protectors Against Cancer
What is the concept of stem cells?
Stem cells hold the remarkable potential to transform into many different cell types within the body. These unique cells act as the body's internal repair system, dividing and renewing themselves to constantly create fresh cells. Unlike specialised cells with singular functions, stem cells remain unspecialised, allowing them to morph into muscle cells, blood cells, or even brain cells. This versatility makes them a promising area of research for treating diseases and injuries.
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| Utilizing stem cells for cancer prevention. |
How do drs generate stem cells?
Doctors acquire stem cells through a few different methods, depending on the type needed and the intended use:
- Adult stem cells: Doctors harvest adult stem cells from consenting adults, typically from their bone marrow or fat tissue. The procedure involves using needles to extract a small sample. These cells can then be directly used in treatments or expanded in a lab setting for future use.
- Embryonic stem cells come from unused embryos created during in vitro fertilisation (IVF) procedures. With proper ethical guidelines, doctors can extract stem cells at a very early stage of development, before the embryo has implanted in the uterus.
- Induced pluripotent stem cells (iPSCs): This is a cutting-edge technique where doctors take mature cells from a patient, like skin cells, and reprogram them back into an embryonic-like state. These reprogrammed cells then have the potential to become various cell types.
What are the types of stem cells?
There are two main categories of stem cells: embryonic stem cells and adult stem cells. Each has unique properties and potential uses.
Embryonic stem cells (ESCs):
- Derived from unused embryos created during in vitro fertilisation (IVF) procedures.
- Pluripotent, meaning they can develop into any cell type in the body.
- ESCs hold great promise for regenerative medicine due to their versatility.
- Ethical considerations surround their use due to the destruction of the embryo.
Adult stem cells (ASCs):
- Found in various tissues throughout the body, such as bone marrow, blood, fat, and muscle.
- Multipotent, meaning they can differentiate into a limited number of cell types specific to their tissue of origin.
- Adult stem cells are less ethically controversial than embryonic stem cells.
- Currently, some established medical treatments, such as bone marrow transplants, are utilising.
Induced pluripotent stem cells (iPSCs):
- It is a relatively new type of stem cell in a lab setting.
- It was made by reprogramming mature cells, such as skin cells, back into an embryonic-like state.
- Offer the potential of pluripotency without the ethical issues of embryonic stem cells.
- It is still under development but holds promise for future regenerative medicine applications.
Which form of the stem can be helpful for cancer patients?
Two main types of stem cells have potential applications for cancer patients:
- Hematopoietic stem cells (HSCs): These adult stem cells reside in bone marrow and blood. They can differentiate into all mature blood cells, including RBCs, WBCs, and platelets. In some cancers, particularly those affecting the blood and bone marrow, like leukaemia, lymphoma, and myeloma, HSCs play a crucial role in a treatment called a bone marrow transplant. During this procedure, doctors harvest HSCs from a healthy donor (allogeneic transplant) or the patient themselves (autologous transplant) and infuse them back into the patient after high-dose chemotherapy or radiation. These healthy stem cells then repopulate the bone marrow and help restore the body's ability to produce healthy blood cells.
- Mesenchymal stem cells (MSCs): Adult stem cells reside in various tissues throughout the body, including bone marrow, fat, and umbilical cord blood. While not directly replacing cancerous cells, MSCs offer potential benefits in cancer treatment through several mechanisms:
- Immunomodulation: MSCs can suppress the overactive immune response sometimes associated with cancer treatments and potentially help reduce graft-versus-host disease (GVHD) in allogeneic bone marrow transplants.
- Anti-tumour effects: Studies suggest MSCs may have properties that inhibit tumour growth and spread.
- Tissue regeneration: MSCs may promote the repair of healthy tissues damaged by cancer treatments.
It's important to note that MSC therapy for cancer is still under investigation. While some clinical trials are ongoing, they are not yet considered a standard treatment for cancer patients.
Here's a key takeaway: Drs use Hematopoietic stem cells (HSCs) in established cancer treatments like bone marrow transplants. Mesenchymal stem cells (MSCs), on the other hand, show promise for future applications in cancer treatment but are still under active research.
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| Use of stem cells in the prevention of cancer |
What are the two types of stem cell transplant therapy?
Autologous Stem Cell Transplant:
- Doctors take stem cells directly from the patient.
- This process usually involves collecting stem cells from the patient's blood or bone marrow before receiving high-dose chemotherapy or radiation for their cancer.
- After the treatment wipes out cancerous cells, the collected stem cells get put back into the patient's body.
- These healthy stem cells help rebuild the immune system and allow the body to produce healthy blood cells again.
2. Allogeneic Stem Cell Transplant:
- This transplant uses stem cells from a healthy donor.
- The donor can be a sibling with a matching tissue type (HLA match) for better acceptance by the body (simplifies "human leukocyte antigen").
- Alternatively, doctors can use stem cells from unrelated donors found in registries if there's a good HLA match.
- It is similar to autologous transplants, where patients get high-dose chemotherapy or radiation before receiving an infusion of donor stem cells.
- The new stem cells then take root (a simpler alternative to "engraft") in the patient's bone marrow and begin making healthy blood cells.
What are embryonic stem cells?
Embryonic stem cells (ESCs) are pluripotent stem cells, meaning they can develop into any cell type found in the human body. They originate from a very early stage in embryonic development, specifically the inner cell mass of a blastocyst – a pre-implantation embryo just 4-5 days old.
Here's a breakdown of key points about embryonic stem cells:
- Embryonic stem cells (ESCs) are pluripotent stem cells, meaning they can develop into any cell type found in the human body. They originate from a very early stage in embryonic development, specifically the inner cell mass of a blastocyst.
- Pluripotency: Can differentiate into all three embryonic germ layers (ectoderm, mesoderm, endoderm), giving rise to all the specialised cell types in the body (muscle cells, nerve cells, blood cells, etc.).
- Potential: It holds immense promise for regenerative medicine, offering the possibility to treat diseases and injuries by regenerating damaged tissues.
- Ethical considerations: Their use is ethically controversial because it involves the destruction of a blastocyst, which some consider the beginning of human life.
Current status of ESC research:
- Extensive research is ongoing to explore the therapeutic potential of ESCs.
- Researchers are actively tackling challenges like immune rejection and tumour formation that could arise if drs transplant ESCs into patients.
- Strict ethical guidelines are in place to ensure the responsible use of ESCs in research.
Alternatives to ESCs:
- Induced pluripotent stem cells (iPSCs) are a newer development offering similar pluripotency but without the ethical concerns. These are adult cells reprogrammed back to an embryonic-like state.
- Adult stem cells, which can be less versatile, are currently used in some medical treatments and offer a less controversial alternative.
How do "embryonic stem cells" target cancer cells?
Embryonic stem cells can potentially target cancer cells through several mechanisms:
1. Differentiation: Embryonic stem cells can differentiate into various cell types. Scientists can direct these cells to differentiate into specific cell types that target and destroy cancer cells. For instance, researchers can prompt embryonic stem cells to differentiate into immune cells or specific cell types possessing anti-cancer properties.
2. Delivery of therapeutic agents: Researchers can engineer embryonic stem cells to produce and directly deliver therapeutic agents to cancer cells. These therapeutic agents may include drugs, proteins, or nanoparticles to inhibit cancer growth or induce cell death.
3. Tumour-homing ability: Embryonic stem cells can migrate towards tumour sites in the body, which they exploit to deliver therapeutic agents specifically to cancerous tissues while less damage to healthy tissues.
4. Immunomodulation: Embryonic stem cells have immunomodulatory properties, meaning they can regulate the activity of the immune system. By modulating the immune response, embryonic stem cells may help to enhance the body's natural ability to eliminate cancer cells.
5. Targeted gene editing: Embryonic stem cells can be genetically modified to express specific genes or gene-editing tools that target cancer cells. Drs use these modified stem cells to deliver these gene-editing tools directly to tumour cells, enabling precise editing of the cancer cell's DNA to inhibit its growth or induce cell death.
Here are some alternative approaches that are for targeting cancer cells:
- CAR T-cell therapy: This immunotherapy uses genetically modified T cells (immune cells) to recognise and attack cancer cells.
- Antibody-drug conjugates (ADCs): These ADCs combine antibodies that target cancer cells with drugs that kill them.
These approaches offer more targeted options for directly eliminating cancer cells. Overall, embryonic stem cells hold promise as a potential tool for targeted cancer therapy for ongoing research.