0. Introduction Flashcards
Define CTE
Cell- and Tissue Engineering. The development of biological constructs for implantation
Consider the difficulties in cell- and tissue engineering (structure vs. function)
It is easier to replace structure than function, e.g. metabolism and signalling.
Structures may be bone, cartillage or tendon. Function may be liver, pancreas, heart.
What kinds of biological material may be transplanted?
Material only (tissue inducing substances)
Cells only
Cells seeded in material
What is the aim of transplanting tissue-inducing substances?
T o induce the host cells to secrete signal molecules, such as growth factors
What is the aim of transplanting cells only?
The cells may replace the original cells to provide function. Stem cells may induce homeostasis without integration, by signaling molecules. Allows for cell manipulation before transplantation
What is the aim of transplanting seeded matrices?
May be either open or closed system. Open system: The cells are seeded in a matrix and transplanted. Closed system: the cells are separated from the body by a membrane, which avoids attack of the cells by antibodies, and allows transport of nutrients and waste
What are some observations seen in cell-transplantation?
Isolated cells reform the tissue, due to its effect on the microenvironment. All tissues undergo remodelling, so the entire tissue does not have to be created in vitro. Tissues cannot be transplanted in large volumes due to lack vascularisation
Define TEMPs
Tissue-engineered medical products
Newer cell-based therapies that incorpate significant cellular manipulations in vitro
Give examples of TEMPs
Chrondrocytes for cartilage repair
Liver and kidney cells grown on extracorporal devices
Encapsulated beta-islets for diabetes type I
Sheets of dermal fibroblasts for ulcers and burns
Genetically modified myocytes for treatment of muscular dystrophy
Define CT
Cell-based therapies
Exploits stem-cell capacity, rather than depending on their long-term integration in host tissue
Define autologous
Donor and recipient is the same patient
Define allogenic
The donor and recipient is from the same species
Define syngenic
Donor and recipient are different individuals that are genetically identical, such as homozygous twins
Define xenogenic
Donor and recipient are of different species
What is the most common origin of cells for transplant (both in the present and historically)?
Traditionally most transplants were allogenic, but it is becoming more common with autologous transplants due to ex vivo modifications that may be performed on the cells
What may be an issue with autologous cell transplants?
The autologous cells may have the same susceptibility towards a given disease, since the individual’s cells already once have developed the disease. Therefore it may be necessary to reprogramme or otherwise modify the cells before transplantation
What is the main challenge in transplanting tissue engineered constructs?
Rejection of the transplant
RIsk of graft vs. host disease
How do extracellular signal molecules leave the secreting cell?
Signal molecules such as proteins, peptides, nucleotides, steroids, carbon monoxide, etc., are released by exocytosis
Some signal molecules diffuse across the cell membrane