Chahal Flashcards
What is the objective of tissue engineering? What three components are
usually seen as a part of tissue engineering strategies? What are the roles of
these different components?
The objective of tissue engineering is to regenerate tissues rather than using non-biological synthetic replacements.
The three main components are cells, which are responsible for the synthesis, scaffold, which is for providing structural support and the right environment, and growth factors to facilitate the growth.
Both iPSC and ESC are pluripotent stem cells. What is iPSC and ESC? What
are their sources and what does “pluripotent” mean? Discuss the feasibility of
using iPSCs vs ESCs for regenerative medicine
ESCs, embryonic stem cells, are harvested from embryos, and therefore have quite a few ethical issues associated with them. They can differentiate into every cell of the body (pluripotent), but have to come from somewhere. If they are only extracted they could still be allogenic, and still cause rejection by the host. One way around this problem is to exchange the nucleus for a nucleus from a somatic cell from the host, but this also raises some ethical questions. They are cheap though. There is also the concern about mutation rates and risk of tumor growth.
iPSCs are induced pluripotent stem cells. They use the host’s own cells, and induce them to revert to a pluripotent stage. This means that they are autologous, and there is no rejection problem. However, there might still be a problem in that if they can be induced, they might revert back. They are also expensice, there is a risk of cancer.
What material properties are important to consider when selecting a material
for tissue engineering applications?
Material properties to consider when selecting a material for tissue engineering applications:
- Biocompatibility/lack of toxicity
- biodegradable
- surface properties
- mechanical performance
- clinical feasability
- Cell source
- Scaffold construction
- Cell seedling
- Culture environment
- Matrix production analysis
- Mechanical properties of cell-scaffold construct and suitable animal models.
- Immunological rejection of the scaffold or cells
- The scaffold has to provide nutrients, oxygen, waste transport
- Delivery methods of GFs, they can’t spreas to other tissues. Could use plasmid vectors containing the GFs.
Tissue engineering is a relatively new and upcoming field. Discuss some of
the challenges associated with tissue engineering.
Graft rejection, ethical issues regarding the origin of the stem cells, price, serum used for cell cultivation (currently fetal calf serum, but it could contain viruses etc.), different cells thrive in different environments, have to be able to recreate those.
Below is a figure highlighting essential ECM components. What is the
extracellular matrix (ECM)? Explain how natural ECM can be used as in
inspiration to create synthetic mimics for tissue engineering
The extracellular matrix is a network of macromolecules that surrounds the cells. It provides physical scaffolding for the cells in the body, and helps mediate cell-cell and cell-ECM communications by being a channel for signaling molecules. It can also facilitate cell migration. The scaffold used in TE should mimic the functions and structure of the ECM.
The ECM is tissue-specific, and has a multitude of functions. Is comprises a densely populated microenvironment that allows for efficient cell-cell and cell-ECM communications, which can help determine cell fate and function. By studying the structure and main functions (which can be difficult to do) of the ECM in certain tissues, one can make mimics that have the necessary structures and functions.
The ECM provides a cell anchorage, provides structural integrity to the tissue, is a channel for signaling molecules, has a reservoir of growth factors, is important in natural tissue remodeling and homeostasis, and generally facilitate cell migration. These are all properties that the synthetic mimics desire.
