1
Q
Biocompatibility
A
-Materials that elicit minimal adverse responses
2
Q
Local response
A
An inflammatory defense that occurs at tissue level (seen in skin, mucosal tissue, epithelium)
3
Q
Systemic response
A
An inflammatory defense that is spread throughout the body via blood or lympathic fluids. Less common with biomaterials, associated with lymphocytes.
4
Q
Wear debris
A
- associated with ultra high molecular weight polyethylene implants
- Fragments are phagocytized by macrophages but can’t be digested, releasing lysosomal enzymes causing a loosening and failure of the implant
5
Q
In vitro and In vivo
A
In vitro: testtube
In vivo: life
6
Q
What the Body is doing to the Material:
A
1) Loosening
2) Phagocytosis
3) Corrosion/Wear/Tear
4) Fracture of implant/bone
5) Rejection of Implant
7
Q
What the Material is doing to the Body:
A
1) Hemolysis/Thrombosis/Coagulation
2) Immunogenic
3) Inflammation
4) Toxicity
5) Tumorogenesis
6) Infection
7) Promotes encapsulation
8
Q
Hemolysis/Thrombosis/Coagulation
A
Hemolysis: lysis and breaking open of red blood cells causing the release of hemoglobin into surrounding fluids
Thrombosis: a blood clot forms in circulatory system, impeding blood flow
Coagulation: clot formation
9
Q
Inflammation
A
- An inflammatory cytokine response
- Beneficial: initiate tissue repair, rid body of harmful agents
- Deleterious: may have over active response to minor agent or self, autoimmune disease
- Acute vs Chronic
10
Q
Bacterial Biofilms
A
Adherent bacteria for a glycocalyx coat, this coat protects bacteria from phagocytosis and antiobiotics = bad
11
Q
Encapsulation
A
- The coating or engulfing of particles within a continuous matrix
- Many implants trigger fibrous encapsulations, which confines the foreign material and keeps it separated from surrounding normal tissue
12
Q
Phases of Wound Healing w/ Biomaterials
A
1) Hemostasis: stop bleeding (platelets, fibrin)
2) Inflammation: initiates wound repair (neutrophils, macrophages, lymphocytes)
3) Proliferation/Granulation: pulls the wound close, beginning of scar formation (fibroblast, epithelial cells, endothelial cells)
4) Fibrosis: formation of fibrous connective tissue surrounding the foreign object (fibroblasts)
5) Foreign body reaction: phagocytosis occurs of foreign object (FBGC, fused macrophages)
6) Remodelling/Maturation” development of the final proper tissue (everything)
13
Q
In vitro tests
A
Compared to in vivo tests, these tests are high-throughput, fast, inexpensive, not always relevant to in vivo results
14
Q
Kilgman Maximization Test
A
-Determine allergic or sensitizing capacity to repated or prolonged exposure of agent
-Characterized by delayed reaction, independent of dose
-Evaluates a system response, often seen in skin
Steps: intradermal injection in guinea pigs, 7-9 weeks later, inject agent/material elsewhere, then look for reaction on skin
15
Q
Irritation Tests
A
Evaluates a local tissue inflammation, usually seek in skin
Intradermal injection into albino rabbit
16
Q
Genotoxicity Test
A
- Evaluates genotoxicity effects, DNA destruction, gene mutation, and chromosomal abnormalities
- Uses a mutation reverting bacteria that does not produce histidine (Salmonella)
- Uses media that lacks histidine
- A mutagen may cause bacteria to grow without external source of histidine
- The mutagenicity of agent = the number of bacterial colonies in media
17
Q
Prediction of Cell Yields
A
- cell yield on the day of surgery is a critical factor
- seeding cell desnity or cell number is commonly critically defined in most cell therapy protocols to assure a certain therapeutic effect
18
Q
Serum-Free conditions
A
- ex vivo expansion
- human serum not realistic
- FBS: -possible risk of contamination, immunological reactions against xenogeneic serum
19
Q
Scaling-up Cell Microencapsulation
A
Transgenic Cell Encapsulation > Encapsulated Cell Culture > Transplantation
- Follow GMP procedures
- Scaling-up cell encapsulation: 3D air supply and multinozzle outlet
- Once therapy reached goal / when undeseriable deleterious effects occur, noninvasive
- monitoring and deactionation/elimination of the encapsulated cells are critical
20
Q
Cell Storage - Cryoprotectants
A
- Minimize damage caused by ice crystal formation, cytotoxic to some extent
- Scaled-up cryopreservation for macroscopic tissue problems related to heat and mass transfer
- Large products need longer incubation time with cryoprotectants = lower survival rate
21
Q
Cell Storage - Vitrification
A
Prevents ice formation throughout the entire sample during cooling and warming process
22
Q
Cell Storage - Dry Storage
A
- long-term unfrozen storage at ambient temperature
- Low cost (not yet a reality)
- Many organisms can undergo anhydrobiosis to survie in a completely dehydrated state for an extended time and resume activity upon rehydration
23
Q
Determination of Cell Fate
A
- Biological, Chemical, Mechanical, Physical Properties
- Stimuli affecting stem cell differentation
24
Q
Biological Properties
A
- Growth factors
- Genetic material
25
Chemical Properties
- O2
- Free radicals
- Contact angle
26
Surface Hydrophobicity
- Assessed by measuring contact angle through water spread on droplet on a surface
- The lower the contact angle, the more hydrophilic the surface is
- Superhydrophilic (<5), Hydrophilic (<90), Hydrophobic(90-150), Superhydrophobic(150-160)
-Maximum adhesion of fibroblasts: 60 - 80 degrees, for osteoblasts: 0 - 106 degrees
27
Surface Charge
- Increased polarity, increased migration
- Negative charge, increase chondrocyte differentation
- Positive charge: improve neuronal attachment, osteoblasts & fibroblasts spreading
28
Cell Responses to Surface Chemistry
- Immediately after scaffold implantation, protein adsorption occurs, which mediates cell adhesion
- Integrins affect ECM deposition, cell proliferation, and differentation
- Focal adhesion: interaction between cells and biomaterial scaffold
29
Mechanical Properties
- Shear
| - Stiffness
30
Static vs. Shear (Dynamic)
Static Culture: nonhomogenous growth, nonhomogenous differentation, low O2 and nutrient diffusion, difficulty of monitoring and control, low productivity
Dynamic Culture: better homogeneity, O2 and nutrient supply during exposition to shear stress
- Higher cellular growth
- Higher control and productivity
31
Tissue's Young Modulus
- Given by resistance offered by the tissues to deformation effects, i.e. the tissue stiffness
- Use rheometer to measure cell adhesion force on substrate softness
32
Substrate stiffness and cell fate
- Stiffness gradients mimicking In Vivo tissue variation regulates MSC fate
- Durotaxis: the movement of a cell along a rigidity gradient
33
Physical Properties
- 3D
| - Pore size
34
Surface Roughness
- Modulates biological response of tissue in contact with the implant
- Direct influence on cell morphology, proliferation, and phenotype expression
- Cells grown on microrough surfaces stimulated towards differentation (response is different depending on cell type)
- Larger cells like macroroughness
35
Pore Size
Small pores: affects center cells getting nutrients
Larger pores: affect stability of scaffold, limits cell migration
-Specific cells require different pore sizes for optimal attachment, growth and motility
36
Porosity
- Percentage of void volume in the materials
| - Attempts to link scaffold porosity to cell performance have not been successful
37
Dynamic Scaffolds
- Biodegradable scaffolds, rate of degradation / dissolution rates
- Cells that proliferate rapidly require scaffolds with higher degradation rates
- Stability requires longer-lasting material
38
Cell Sorting
- If cells from two tissues are mixed, they sort according to their tissue surface tensions
- Intercellular adhesion and cell surface tensions dictate that four final configurations are possible: checkerboard, partial engulfment, complete engulfment, separation
- Could be tuned through expression levels of adhesions molecules displayed by the cells
39
Decellularization
Cadaveric heart > decullularization (w/ physical, chemical, enzymatic treatment) > recellularization (via perfusion bioreactor) > functional and vascularized heart (requires progenitor cells and/or cardiac cells)
40
Bioprinting
1) Inket bioprinter
2) Microextrusion bioprinter
3) Laser-assisted bioprinter
Applications: Biofuels, drug discovery, bioprinted organs, medical devices, artificial tissue
41
Nano
-Structures the size of 100 nanometers or smaller in at least one dimension
42
2 Approaches of Nanotechnology
1) Top-down approach: creating nano-scale materials by physically or chemically breaking down larger materials
2) Bottom-up approach: Assembling nano materials atom-by-atom or molecule-by-molecule (self-assembling)
43
Nanobots
- Detection of toxic components in environment
- Drug delivery
- Biomedical instrumention
44
Nanosponges
- for antiobiotic resistant infections
| - toxin attaches to nanosponge, RBC transport them to liver where they are removed harmlessly
45
Integumentary system
1) Skin: epidermis, dermis, hypodermis
| 2) Accessory Structures: hairs, nail, glands
46
Epidermis
- Most superficial layer
- Stratified squamous epithelium
- Avascular
- Nutrients and oxygen diffuse from capillaries in the dermis
- 4 layers in thin skin, 5 layers in thick skin
47
4 Main Cells of Epidermis
Keratinocytes, Melanocytes (contain melanin), Langerhans cells (immune function), Merkel Cells (respond to touch)
48
Dermis
- Anchors epidermal accessory structures (hair follicles, sweat glands)
- Two fibers: collagen (strong, flexibility) and elastic (limits flexibility, permits stretching)
- 2 layers, Outer Papillary and Deep Reticular
49
Outer Papillary Layer
- Consists of areolar & adipose tissue
- Contains smaller capillaries, lymphatics and sensory neurons
- Has dermal papillae projecting between epideral ridges
50
Deep Reticular Layer
-Consists of dense irregular connective tissue & adipose
51
Lines of cleavage
- Establish important patterns
- A parallel cut remains shut, heals well
- A cut across (right angle) pulls open and scars
52
Hypodermis
- Deepest layer, aerolar and adipose CT
- Regulates temp and stores energy (fat deposits)
- Sute of subcutaneous injections using hypodermic needles
53
Hair
- UV protection, insulation, protect eyes, guards openings, touch sensation
- doesnt grow on: palms, soles, lips, portions of external genitalia
- Arrector pili (muscle), sebaceous glands
- 3 Different Types: lanugo, vellus, terminal
54
Skin Development
- Ectoderm Origin - between 5 and 8 weeks
| - Cells that respond to NGF turn into nervous tissue, cells that don't turn into skin
55
EGF
- Epidermal Growth Factor
- Powerful peptide growth factor
- Produced by glands (salivary and duodenum)
- Used to grow skin grafts
- Promotes division, acceleratres keratin production, stimulate epidermal repair, stimulates glandular secretion
56
Repair of the Integument
1) Blood clot and scab formation
2) Cellular migration
3) Epidermis covers granulation tissue
4) Epidermis covers scar tissue
57
Cyanosis
- Bluish color to skin/nails
| - Hemoglobin depletion, caused by severe reduction in blood flow or oxygenation
58
Erythema
- Redness of skin
- Dermal capillary enlargement
- Inflammation, infection, burns
59
Vitamin D
- UV radiation
- Produce cholecalciferol
- Liver and kidneys convert vitamin D into calcitriol
- Essential for bone maintenance and growth
- insufficient vitamin D can cause rickets
60
Burn Classification
1) First-degree burn (sunburn)
2) Second-degree burn (blister)
3) Third-degree burn (bad shit lol)
61
Melanoma
```
A = Asymmetry
B = Border
C = color
D = diameter
```
62
Autografts
- Recommended for deeper dermal wounds that heal slowly & inadequately
- Split-thickness graft (skin from same person, different body part)
- Healing depends on thickness of underlying dermis in the graft
63
Allograft
- Skin from cadavers frozen and used as needed
| - Some living donors
64
Amnion
-Collected from placenta used for partial thickness burns
-One of most effective biological skin substitutes
Advantages: improved pain, lack of immunological markers, antibacterial
65
Classifications of Skin Substitions
Duration of cover: permanent, semi-permanent, or temporary
Anatomical structure: epidermal, dermal, dermo-epidermial
-Skin substitution composition: cellular or acellular
Biomaterial: biological (autologous, allogeneic, xenogeneic) or synthetic (biodegradable, non-biodegrabled)
66
Cell Spray
- Epidermal Autologous
| - Keratinocytes cell suspension
67
Rediheal
- Fully granulated in 7 days
- No infection developed during treatment
- Significant healing, minimal scarring, hair regeneration
68
SIS
- small intestinal submucosa
| - induces host tissue proliferation and regeneration
69
Does Jell-O make our hair, skin, and nails grow faster? How can hair grow faster?
-Gelatin is protein derived from collagen, denser skin collagen levels have been found and connection between collagen intake and hair thickness growth exists
70
Why did Michael Jackson's skin turn lighter in adulthood? How can I tan faster? How bad are tanning beds? Does tan = damage?
He had vitiligo and used treatments to make his skin whiter. Vitiligo is an autoimmune disorder in which lymphocytes attack melanoncytes. To tan faster, go outside and make sure you wear sunscreen. Tanning beds are bad for you. Increase in melanin pigment in skin (tan ) is a sign of damage, due to increased UV radiation, melanin produced to attempt to protect skin.
71
Some criminals sand off their fingerprints. Is this permanent? Why does skin get irritated when using certain lotions / soaps?
Fingerprints tend to grow back over time, not permanent. Contact dermatitis, can be due to allergies, inflammation, infection.
72
Why does skin/hair get dry? Oily? Why do some have more oil than others?
For dry hair/skin, scalp doesn't make enough oil to moisturize your hair, or your hair lets moisture escape too easily. Too oily? Sebaceous glands overproduce oil, causing breakouts as sebum mixes with dead skin and gets stuck in pores. It is genetic, environmental, and livestyle factors.
73
If you stopped washing your hair, would it be healthier? How often should you bathe?
Your hair will become dirty, and could lead to discomfort. While sebaceous glands are good at replenishing your hair with nutrients, your hair could stop growing. DEPENDS I GUESS. Twice a week for bathing.
74
Why do we get splint ends? Why does hair fall out in the shower? Why does hair frizz in humidity?
Split ends are the result of small damaging factors to hair. Often caused by styling, brushing, heat and friction. Hair falls out in the shower due to the physical force of water hitting the scalp, causing looser hair strands to disconnect and fall out. It's normal to shed. Hair frizzes in humidity because more external heat causes hydrogen bonds to form between water molecules and protein in your hair, physically propping them up.
75
What is the difference between blackheads and pimples? How does 24-hour make-up work?
Blackhead: forms when a pore is only partially clogged, allowing some trapped sebum to slowly drain to surface
Pimple: develop when a plug of oil and dead skin become trapped in pore, stopping the pore from opening. Usually red and inflamed due to bacteria.
76
Why do you get itchy when you get nervous? Why does a person's leg tingle all the time?
Lack of blood supply to an area due to inadequate oxygen intake caused by anxiety symptoms. Could be because of posture, MS, diabetes, peripheral artery disease, or fibromyalgia.
77
A victim of a fire is admitted to the emergency room. You observe considerable damage to the epidermis and dermis of both arms and the front and back portions of the trunk. You also note patches of charred skin and insensitivity to touch. What type of burn is indicated by these characteristics? How much of a person's body is burned. What is the probability of scarring? Explain your answer.
Full Third-degree burn, charred skin and insensitivity indicate damage to all layers of the skin, vascularization + touch corpuscles destroyed. The burn causes scarring and requires skin grafts and pressure bandages. 9% (both arms) + 9% (front and back of trunk) = 18% burned
78
Explain why a person who lived in a dark cave might have weaker bones and teeth than someone who lived outdoors, even if their diets were the same.
Skin cells produce cholecalciferol (vitamin D) when exposed to UV radiation, which is converted in the liver and kidneys to calcitriol which aids in absorptions of calcium and phosphorous, which are very important to growth of bones and teeth. This is why a person in a dark cave, not exposed to UV radiation, will not have the same calcium + phosphate levels as THE SUN PEOPLE
Tissue Engineering 1
flashcards
Decks in class (4)
# Cards
