Term
| T/F: The "creep" is a nuisance (i.e. undesirable behavior) for most tissue engineering applications and that is why we call it a creep. |
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Definition
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Term
| T/F: The stress is a measure of the internal forces acting within a deformable tissue |
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Definition
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Term
| T/F: We say that a tissue strains when it makes a strenuous effort to resist the stress. |
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Definition
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Term
| T/F: Without water inside the cartilage, it would not exhibit creep. |
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Definition
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Term
| T/F: The disk of cartilage is only exhibiting creep without any instantaneous strain. |
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Definition
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Term
[image]
T/F: These data show that cell proliferation increases when the concentration of the polymer poly(HEMA) falls. |
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Definition
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Term
[image]
T/F: When the concentration of this polymer reaches zero, cells proliferate rapidly, because no more polymer is present |
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Definition
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Term
[image]
T/F: These data show that as the concentration poly(HEMA) increases, cell spreading rises. |
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Definition
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Term
[image]
T/F: Cell spreading and cell proliferation are positively correlated. |
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Definition
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Term
[image]
T/F: Cell spreading increases when the concentration of poly(HEMA) decreases, because this polymer tends to lower cell adhesiveness. |
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Definition
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Term
| T/F: The good thing about the microcontact-printing technique is that it produces micro-patterning of cell environment that cannot be modified dynamically. |
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Definition
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Term
| T/F: Almost all implanted polymers induce a unique inflammatory response termed the foreign-body response. |
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Definition
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Term
| T/F: The electrospinning technique for creating porous scaffolds involves subjecting the polymer to a rotating electric field. |
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Definition
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Term
| T/F: Salt crystals are used in porogens in extrusion methods for making biocompatible scaffolds for tissue engineering. |
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Definition
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Term
| T/F: The high-internal-phase emulsion technique for producing porous scaffolds uses an aqueous continuous phase around polymer droplets in an emulsion. |
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Definition
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Term
| T/F: The adult epidermis has three stem-cell compartments, one of which is normally quiescent. |
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Definition
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Term
| T/F: The stem cell in the epidermal proliferative unit is in the cornified layer. |
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Definition
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Term
| T/F: The epidermal proliferative unit stem cell and the hair follicle stem cell have a common origin during development of the skin to the bulge stem cell. |
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Definition
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Term
| T/F: Hair grows in cycles of various phases: anagen is the growth phase; catagen is in the involuting or regressing phase; and telogen, the resting or quiescent phase. |
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Definition
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Term
| T/F: One derives embryonic stem cells directly from the oocyte. |
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Definition
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Term
| T/F: The use of embryonic stem cells never involves tissue-culture expansion, since it will cause them to differentiate. |
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Definition
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Term
| T/F: Obtaining amniocytes is a good first step to prepare autologous engineered tissues for fetuses or newborn babies. |
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Definition
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Term
| T/F: The amniotic fluid is rich in mesenchymal stem cells. |
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Definition
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Term
| T/F: Mesenchymal amniocytes have shown potential for mesodermal differentiation into fibroblasts but nothing else. |
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Definition
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Term
| T/F: Somatic-cell nuclear transfer is a good idea to combat immunogenicity by moving cells from an autologous tissue to an allogenic one. |
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Definition
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Term
| T/F: Because of injury, astrocytes will atrophy and exhibit downregulation of glial fibrillary acid protein (GFAP). |
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Definition
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Term
| Microglia proliferate after injury and assume a more compact "amoeboid" morphology. |
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Definition
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Term
| In astrogliosis, the mesh of astrocytic processes eventually becomes so strong and compact that removal of the implant electrode does not result in the collapse of cellular processes into the implantation tract. |
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Definition
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Term
| Metallic electrodes do not cause foreign body response, as we saw with polymeric materials, and thus no significant loss of neurons occurs. |
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Definition
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Term
| Strategies to improve biocompatibility through purely structural changes in implant electrodes do not appear to be as effective. |
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Definition
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Term
| Faradaic charge-injection mechanisms inject charge through the electrode-electrolyte double layer. |
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Definition
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Term
| For all high-surface-area electrodes, pore resistance imposes a geometric limitation on the increase in charge-injection capacity that one can obtain by increasing the ratio between the electrochemical surface area and the geometric surface area. |
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Definition
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Term
| The cyclic voltammogram of platinum electrodes is not rectangular because of e.g., peaks associated with the oxidation and reduction of a surface oxide. |
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Definition
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Term
| The cathodal charge-storage capacity of an electrode implanted inthe brain is constant at least over the course of many weeks. |
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Definition
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Term
| High-charge-capacity coating increase the charge-transfer resistance of electrodes. |
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Definition
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Term
[image]
What is the name for this equation? |
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Definition
diffusion/reaction equation
*this is a combined equation |
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Term
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Definition
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Term
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Definition
| maximal uptake rate constant per cell |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| spatial distance from source |
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Term
[image]
What can affect x? |
|
Definition
convection & electric fields
*note: x refers to the spacial distance from the source
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Term
[image]
What can affect KM? |
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Definition
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Term
| What does the flux of molecules within a matrix depend on? |
|
Definition
diffusion, convection (fluid velocity U) and possible electrical migration
*note: flux is a reference to the flow |
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Term
[image]
What is the name of this equation? |
|
Definition
Flux
*note: flux is a reference to flow |
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Term
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Definition
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Term
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Definition
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Term
|
Definition
|
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Term
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Definition
|
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Term
|
Definition
| hindarance factor for convection |
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Term
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Definition
|
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Term
[image]
What are the intrinsic transport parameters? |
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Definition
|
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Term
[image]
What is the importance of the first term? |
|
Definition
| Flux increases with the number of pores |
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Term
[image]
What is the importance of the second term? |
|
Definition
Fick's law
*diffusion means that the flow is being dispersed (spreading out) which will subtract from the flux so this term is negative |
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Term
[image]
What is the importance of the third term? |
|
Definition
| The xi term determines the sign of the third term. Positive particles move with the field, contributing to flux whilst the negative charges move against the field which detracts from the flux. The mu represents mobility in terms of charge and friction while x represents the number of particles. The more particles, the greater the flux. |
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Term
[image]
What is the importantance of the fourth term? |
|
Definition
The omega represents the ECM fricition that slows convection.
The rest of the term represents number of particles which is directly related to flux. |
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Term
| What affects molecular transfer through tissue? |
|
Definition
| continuity law (rate of change of concentrations), electroneutrality (must be 0!) and Donnan equilibrium (both the matrix and solutes are charged) |
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Term
[image]
What is the name of this equation? |
|
Definition
|
|
Term
[image]
What is this equation? |
|
Definition
|
|
Term
[image]
What is this equation? |
|
Definition
|
|
Term
[image]
What is this equation? |
|
Definition
| Cell migration which is similar to that of molecular diffusion and convection. |
|
|
Term
[image]
What is the first term on the right hand side? |
|
Definition
| Cell dispersion down the gradient of cell density |
|
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Term
[image]
What is the second term of this equation? |
|
Definition
| Chemotaxis: motion in direction of gradient of attractant. |
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Term
| What is the relationship between amount of attractant molecules and gradient signal effectiveness? |
|
Definition
| Few attractant molecules mean that the gradient signal is weak (noisy) while too many molecules will overwhelm the receptors rendering the gradient signal ineffective. |
|
|
Term
| What biphasically affects cell migration? |
|
Definition
Amount of attractant
cell/ECM adhesiveness |
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Term
[image]
What can be concluded from this graph? |
|
Definition
| Stress and strain have a direct (linear) relationship for small strains but rises at large strain |
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Term
|
Definition
|
|
Term
[image]
What can be concluded from the above graphs? |
|
Definition
With application of sudden stress, tissues react with fast strain and slow creep.
*think of jabbing a water filled sponge with your finger: quick/easy depression, slow return to normal state. |
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Term
| What causes creep in cartilage? |
|
Definition
|
|
Term
| Why would tissues show hysteresis? |
|
Definition
Tissues are pseudoelastic and with periodic loading, they show an increase in axial stretch with tension.
*the more tissues are exposed to tension, the more elastic the tissue becomes over time. |
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Term
[image]
What model is this and what is its application? |
|
Definition
| Maxwell body for tissue viscoelasticity. |
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Term
[image]
What model is this and what is its applicataion? |
|
Definition
| Voigt body for tissue viscoelasticity |
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Term
[image]
What is this model and what is its application? |
|
Definition
| Kelvin body for tissue viscoelasticity |
|
|
Term
| What are the factors for molecular flux within a matrix? |
|
Definition
| Diffusion, convection, and possible migration with an electric field |
|
|
Term
| What is cellular migration dependent on? |
|
Definition
| chemotaxis and diffusion-like motility |
|
|
Term
| What are 2 tissue elastic properties? |
|
Definition
| stress-strain nonlinearities, hysteresis, creep |
|
|
Term
| What is usually the first step in determining biocompatiability? |
|
Definition
|
|
Term
| What is generally used to test cytotoxicity and why? |
|
Definition
| Fibroblasts because they are sensitive to toxins and are easy to grow in the lab |
|
|
Term
| How are cytotoxicity tests performed? |
|
Definition
Direct contact: substance in direct conact with cell monolayer
Agar overlay: substance in contact with agar on top of the cell monolayer
Extract in media or on disc in agar overlay |
|
|
Term
| What are the advantages of natural polymers like collagen and chitosan? |
|
Definition
| high compatability, intrinsic cellular interactions, biodegradable, cell controled degradability and low toxicity by products |
|
|
Term
| What are disadvantages of natural polymers like hynluronic acid, alginate and dextran sulfate? |
|
Definition
| mechanical strength, batch variation and possible viruses from animal derived materials |
|
|
Term
| What are the advantages of synthetic polymers? |
|
Definition
precise control and mass production
tailoredwith a wide range of properties (specific needs designation)
low immogenicity (stimulation of immuno response)
minimize risk of biological pathogens or contaminants |
|
|
Term
| What are the disadvantages of synthetic polymers? |
|
Definition
relatively low biodegradability
can include toxic substances |
|
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Term
|
Definition
| arrangement of pendant group along the polymer backbone |
|
|
Term
| What are the four main types of degradable implants? |
|
Definition
Temporary scaffold
Temporary barrier
Drug delivery device
Multifunctional devices |
|
|
Term
| What bonds in polymers are broken down by hydrolysis? |
|
Definition
ester bonds: C-O bond breaks
peptide (amide): C-N bond breaks |
|
|
Term
| What are hydrogels and what are they used for? |
|
Definition
A unique form of polymers for implantation
formed by crosslined polymers in water or biological fluids |
|
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Term
|
Definition
| self-assembled monolayers |
|
|
Term
|
Definition
Somatic Cell Nuclear Transfer
Theraputic Cloning to generate immunologically compatible tissues
On the left, oocyte without nucleus, on the right, somatic cell nucleus. Combined in blastocyst, in vitro culture. Generation of transplantable autologous tissues |
|
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Term
|
Definition
Fetal Tissue Engineerng. Getting amniotic cells for transplanted autologous tissues.
Amniotic fluid is taken from amniocentesis, tissue engineered in vitro from progenitor cells, for at birth or in utero surgical reconstruction at birth.
Amniocentesis, amniotic fluid test. |
|
|
Term
|
Definition
Ovine diaphragmatic tendon graft used in autologous repair.
Amniotic fluid = lots of MSC/ Mesenchymal Stem Cells. |
|
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Term
|
Definition
3-D Cartilaginous Tube Engineered from MSC. on a PGA scaffold
|
|
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Term
|
Definition
Imunnobarrier of transplanted artificial pancreas. Oxygen Gradients, islet of langerhans cells, immunoisolation membrane. O2, Glucose goes in, Insulin, Lactic Acid, CO2, H+, Metabolic wastes come out, Cells and Proteins are kept out.
Encapsulated cells. |
|
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Term
|
Definition
Possible rejection pathways in immunoisolation/encapsulated cells:
Antigen presenting cell activates response with Major Histocompatibility Complex (MHC). Live cells/dead cells secrete proteins/cell surface antigens. Activate T Cells, Cytotoxic, B, Antibody Forming Cells and Macrophages.
Lymphokines produced by Lymphocites.
Humoral Response come from Antibody Forming cells, which makes antibodies, complement components, naturally occuring antibodies, autoimmune antibodies. |
|
|
Term
|
Definition
Molecular Weights of Immune System Molecules and porous membranes.
Free Radicals, Reactive O, N < Glucose < Shed Antigens < Insulin < Cytokines < Water Soluable Proteins< Transferrin (Iron binding blood plasma glyco proteins) <IgG <C1q<IgM (Immunoglobulin M from B cells)
Only want Glucose, Insulin, Albumin, Tranferrin.
Must use immunosupressive drugs to keep bad stuff out, to avoid costimulation of lymphocytes. |
|
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Term
|
Definition
| Different types of cell division: Cleavage (symetrical daughter cells, Early Embryos) -> exponential growth (cell cultures); Asymmetrical Division (2 daughter cells with different fates) , Stem Cells (Asymmetrical, one to stem, other to differentiate For tissue renewal) |
|
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Term
|
Definition
Autologous. Limited sources of tissues.
Ex Vivo Expansion and Orthrotopic Delivery.
Bioreactive Factors with scaffolding to stimulate endogeneous stem cells. Marrow/Myocardial Regeneration mobilization of stem cells. Differentiation, ex-vivo expansion, bioreactor/natural and synthetic scaffolding. Orthrotopic (In normal position) Delivery, grafts, regeneration. |
|
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Term
|
Definition
Adult Epithelial Cell lines, Potential Stem Cell lines.
Stem cell divides into dividing transit lines, which contains potential stem cells. Further generations differentiate into functional cells. Number of generations depend on cell. Self renewing stem cells. |
|
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Term
|
Definition
Small Intestine Crypts.
Location of Stem celles are clearly defined, arranged spacally in these crypts. Marked by cell migration and mutation markers. Each has 4 to 6 actual stem cells/lineages. 4 Different cell types produced. paneth, goblet, enterocytes, enteroendocrine. Steady and Peturbed. |
|
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Term
|
Definition
Stem Cells in Skin.
SC at base, differentiated go upward. Epidermise Proliferation Unit (EPU) |
|
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Term
|
Definition
| Hair Follicle bulge has stem cells too. 3 cell compartments, anagen hair folicles, EPU, basal and bulge stem cells. Hair grows in phases, anagen, catagen, telogen. Sebaceuous Glands lubricates skin. |
|
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Term
|
Definition
| Hair, Skin surface, Sebum, Follicle, Sebaceous Gland, Bulge. |
|
|
Term
|
Definition
| Different phases of hair growth. Counterclockwise from top: Hair to Telogen, rest phase, to Early Anagen (Active Symmetric Division), Growth Phase, to Anage (Active Asymmetric Division), to Early Catagen (regressive phase) Apoptosis/quiscence occurs (Club/dead hair forms), goes to Bulge/Quiscence. |
|
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Term
|
Definition
ID-ing stem cells/labeling them
1. Label Retaining Cells, 2. Musashi-1 (RNA binding proteins for asymmetric division in early lineages.) 3. S-Phase (Regenenitive) 4. Apoptosis 5. P53 Protein (guardian angel gene) |
|
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Term
|
Definition
| Tongue Stem Cells. Adult Stem Cells in Basal Layers, Tongue Proliferation Units and migration to anterior and posterior columns in filiform papillae. 3 gens to produce cell lineage, has circadian rhythm. |
|
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Term
|
Definition
Keratinized Skin has shortest lineage, Bone marrow and Testies the longest.
Breast < Tongue <Skin < Intestine (limited pluripotency) < large intestine < Bone Marrow < Testis. |
|
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Term
|
Definition
Bone Marrow. Adult pluripotent stem cells.
1. HSCs (Hematopoietic) from blood, 2. SSCs (Skeletal) from bone and structural 3. MAPC (Multipotential Adult Progenitor) everywhere. Murinae 4. Endothelial Precursors. |
|
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Term
|
Definition
| Embryonic Stem Cells. Oocyte to Morula to Blastocyst (inner mass, 30 cells) in trophoectoderm. Cells collected from blastocyst, expanded in vivo culture. |
|
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Term
|
Definition
| ES Cells can be seeded directly onto scaffolding and directed to differentiate into tissue of choice, or expanded ex vivo,and directed to differentiate before seeding onto scaffold. |
|
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Term
|
Definition
ESC made in bioreactors. EGF
3 fold higher yield, more uniform, rounded. Promotes endothelial cells, PDGF promotes vascuar smooth muscle.
A. EC markers of various lipoproteins.
B. Cell cultured, markers of calponin, calcium binding proteins, SM Myosin Heavy Chains, SMMHC.
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|
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Term
|
Definition
Embryoid Bodies of Epithelial Neuronal Tubes (Solid arrows) Blood Vessels (dashed arrows)
Homogeneous EBs.
Directing differentiation with progenitor cells, coculture, growth factors, etc. |
|
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Term
|
Definition
4 Steps to bring tech to clinical use.
Research, Development, Regulatory, Commercialization. |
|
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Term
|
Definition
| Self Assembled Monolayers used to regulate cell movement with electrochemical desorption. (Gathering Ethelyene Glycol terminated monolayers to certain points on surface) |
|
|
Term
|
Definition
| Electrospinning Polymers of different concentrations, make fiber meshes/scaffolds |
|
|
Term
|
Definition
| Electrospinning. Uses electric charge to draw fine fibers from liquid, high voltage, electrostatic repulsion counteracts surface tension, drops are stretched. Taylor Cone erupts from surface. Jet dries in flight, electrostatic replusion whips and elongates, deposited on collector. High porocity results. |
|
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Term
|
Definition
Polymer Scaffold Fabrication: Extrusion
Raw material is melted and and forced through a die to mold into a certain shape. Leaching takes out materials. Leach salt from extruded scaffolds. |
|
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Term
|
Definition
High Internal Phase Emulsion (HIPE)
polymerization of continuous phase around aqueous drops in emulsion. Polygens can be incorporated, polymers are cross linked to make solid network. |
|
|
Term
|
Definition
| Polymer/Ceramic Composites by Solvent Casting or Gas Foaming. Maes scaffolds stronger. PVOH, PVA, PVAI.Water Souable Glue. Polymers are dissolved,salts are added, formed. Solvent Casting. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| In Situ Polymerization with Self Cross Linked Macromers |
|
|
Term
|
Definition
| Porosity. for Diffusivity and Cell attachment. E is Stiffness, Porosity is P. C is constant. 1-P = Relative Density of Material. Squared = Cellular Solids Model |
|
|
Term
|
Definition
Rapid Prototyping of Solid forms.
Basically 3-D printing via CAD/CT |
|
|
Term
|
Definition
Microfluidic Fabbed Scaffolds, Patency (Clear and unobstructed). Uses CAD, Micromachining, Replica Molding, Lamination.
Photolithography for spacial control, lamination to integrate 2D structures into 3D, |
|
|
Term
|
Definition
| Electroplating patterns for structures. Faster than masks of photolithography. |
|
|
Term
|
Definition
| Solid Free-Form Fabrication. StereoLithography (Photopolymerizes liquid) or Selective Laser Sintering (Making things from Powder, heating until particles adhere, definication to solidify). |
|
|
Term
|
Definition
| 3D Printing and Wax Printing. Substrate is deposited in layers. Chemical binder onto powder bed. or Two type of wax in sequence. |
|
|
Term
|
Definition
| Nozzle based systems, Extrusion or Bioplotter. Prints material heated through a nozzle. |
|
|
Term
|
Definition
| Microfluidic systems to deposit cells and ECM by layers. |
|
|
Term
|
Definition
Photolithography. Microcontact Printing to pattern substrates.
PDMS Stamp, Ink with Alkanethiol, patterned SAM.
Elastomers low youngs modolus
A self assembled monolayer (SAM) is an organized layer of amphiphilic molecules in which one end of the molecule, the “head group” shows a specific, reversible affinity for a substrate. |
|
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Term
|
Definition
Micropatterning forces cells to take on certain shapes. When moving, goes blunt end first.
Lamellipodia Extension (Actin Projections at ends of cells) and Adhesion. Rear Release and Retraction.
3T3 = standard fibroblast cell line
COS = recombinant cell line. |
|
|
Term
|
Definition
| Laminar Flow Patterning. Capillaries with different stuff pass streams of fluid from inlets, different parts of cell are treated with different reagents. |
|
|
Term
|
Definition
LFP can create surface concentration gradients to study neuro polarity (Laminin and BSA in serpentine channels). Paralle streams of flow with varying concentrations. Can generate many different characteristics.
Gradient in solution becomes gradiant on surface when proteins adsorb and when hippocampal neurons grow on gradient. Neurons extend Axons towards higher Laminin. |
|
|
Term
|
Definition
Foreign Body Response: Polymers cause inflammation.
FBR is in phases: Nonspecific Protein Adsorption, Inflammatory Cell Recruitment (Neutrophils and Macrophages), Macrophage Fusion to form Foreign Body Giant Cells (FBGC).Ends up in implant being encapsulated.
Days 1 to 2 = more inflammatory cells
days 4 to 8 = deposition of collagen fbers
days 14 to 28 = decrease in cellular content |
|
|
Term
|
Definition
| Polymer Chemistry affects Cell Spreading/Proliferation by adhesiveness. Cell shape moderated by adhesiveness of surface, cell proliferation increases with pHEMA decrease. |
|
|
Term
|
Definition
Cell adhesion is maximal for intermediate hydrophobicity (which rises with water contact angle).
|
|
|
Term
|
Definition
| Percentage of cells adhereing increases with surface concentration of Tripeptide RGD. |
|
|
Term
|
Definition
The Donnan equilibrium applies to two media, one of which contains a charged, non-permeable molecule present. Because of the non-permeable molecule, the individual charged solutes cannot be in chemical equilibrium (i.e., zero-concentration gradients).
***The Gibbs–Donnan effect (also known as the Donnan effect, Donnan law, Donnan equilibrium, or Gibbs–Donnan equilibrium) is a name for the behavior of charged particles near a semi-permeable membrane to sometimes fail to distribute evenly across the two sides of the membrane.[1] The usual cause is the presence of a different charged substance that is unable to pass through the membrane and thus creates an uneven electrical charge.[2] For example, the large anionic proteins in blood plasma are not permeable to capillary walls. Because small cations are attracted, but are not bound to the proteins, small anions will cross capillary walls away from the anionic proteins more readily than small cations. The presence of a charged impermeant ion (for example, a protein) on one side of a membrane will result in an asymmetric distribution of permeant charged ions. The Gibbs–Donnan equation at equilibrium states (assuming permeant ions are Na+ and Cl-):[NaSide 1] × [ClSide 1] = [NaSide 2] × [ClSide 2]
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