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Cell and Tissue Engineering > Lecture 19 - 20 > Flashcards

Lecture 19 - 20 Flashcards

1
Q

What are the functions of bones?

A

Support
Protection
Leverage
Storage (calcium mainly)
Hematopoiesis

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1
Q

What are the 4 types of bones?

A

Long Bones
Irregular Bones
Flat Bones
Short Bones

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2
Q

What percentage of bone is inorganic and what are the top components (3)?

A

67%
Top inorganic components are calcium, phosphate, carbonate

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3
Q

What percentage of bone is organic and what are the top components?

A

33%
Collagen Type-1 and Proteoglycans

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4
Q

Osteon

A

fundamental functional unit of bone consisting of concentric layers of lamelle

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5
Q

Lamellae

A

concentric layers of compact bone

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6
Q

Osteocytes

A

mature cells - pass nutrients and gasses through canaliculi

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7
Q

Canaliculi

A

microscopic canals where osteocytes pass gasses

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8
Q

Lacunae

A

cavity/pits that hold osteocytes

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9
Q

Red bone marrow

A

site of blood production known as hematopoiesis

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10
Q

Yellow bone marow

A

stored fat

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11
Q

Osteoprogenitors

A

stem-cell like

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12
Q

Osteoclasts

A

breakdown bone

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13
Q

Osteoblasts

A

build bone; secrete osteoid

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14
Q

Osteoid

A

immature unmineralized gel-like component of bone; but will become mineralized

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15
Q

Intramembranous Osssification

A

mostly for flat bones; stem cells differentiate into osteoblasts; no cartilage precursor

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16
Q

Endochondral Ossification

A

mostly for long, short, and irregular bones; stem cells differentiate into chondroblasts (which lay hyaline cartilage) that die and form a cavity where osteoprogenitor cells invade the cavities and deposit osteoid

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17
Q

Ossification

A

bone formation

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18
Q

Adult Bone Remodeling Reasons

A
  1. adjust bone architecture to meet changing mechanical needs
  2. to repair microdamage and prevent accumulation of old bone
  3. to maintain plasma calcium homeostasis
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19
Q

autografts

A

patient; requires additional surgery for bone harvesting (high cost)

20
Q

allografts

A

other patients; b/c of donor shortages but risk of immune rejections

21
Q

xenografts

A

animal derived; immune rejections

22
Q

What are 2 common metals for bone engineering?

A

stainless steel and titanium

23
Q

What are 2 common ceramics for bone engineering?

A

HA (hydroxyapatite)
B (beta)-TCP

24
Q

What are the 3 porous ceramic scaffold fabrication techniques?

A

polymer sponge
gel-casting
gel-polymer method

25
Q

Polymer Sponge method

A

ceramic slurry + polymer sponge > organic burn out and sintering yields scaffold

Result: controllable microstructure, low mechanical strength

26
Q

Gel-casting

A

ceramic suspension + monomer + initiator + foaming agents > scaffold

Result: poor microstructure, high mechanical strength

27
Q

Gel-Polymer Method

A

ceramic suspension + monomer + initiator + foaming agents + polymer sponge > scaffold

Result: controllable microstructure, high mechanical strength

28
Q

Why are chitosan/alginate composite materials superior to non-
composite chitosan materials.?

A

they are more biocompatible than synthetic polymers; stable at 7.4 pH; greater mechanical strength

29
Q

What are tests for bone formation?

A
  • Alcian Blue (identify cartilage)
  • Alizarin Red (identify bone)
  • Silver Nitrate (qualitative evaluation of Ca)
  • ALP (staining)
30
Q

What are the 3 types of cartilage?

A

hyaline (flexible and resilient; Collagen Type II)

elastic (highly bendable; Collagen Type II)

fibrocartilage (least elastic; Collagen Type I)

31
Q

Perichondium

A

dense connective tissue sheath that covers cartilage

32
Q

MACI Procedure

A

Cartilage TE regeneration Technique

  1. isolation of chondrocytes from patient
  2. culture of chondrocytes in vitro
  3. placement of chondrocytes onto a biomaterial (HA or collagen)
  4. implantation into lesion site and secured with fibrin glue
33
Q

Regenerative Medicine

A

replaces or regenerates human cells, tissue, or organs, to restore or establish normal function

34
Q

Cell therapy

A

administration of cells to the body to the benefit of the recipient

35
Q

What is the goal of stem cell therapies?

A

transplanted stem cells come into contact with growth factors which program stem cells to differentiate into the tissue surrounding it

36
Q

Hematopoietic stem cell transplantation

A

give rise to blood, lymphocytes and other cells of the immune system and are characterized by the presence of the CD 34 (cluster of differentiation) surface antigens

37
Q

Hematopoietic Stem Cell Transplantation Uses

A

to treat cancer patients with leukemia, lymphoma, and sickle cell anemia and to provide a functional immune system to people with SCID

38
Q

Cryobiology

A

Goal: cells are preserved at cryogenic temperatures, and then restored to original living states with sufficient survival rates, viability, and functionality

39
Q

Cryoprotectants

A

chemicals that lower the freezing point of a solution; ability to form hydrogen bonds with water molecules minimizing water to water hydrogen bonding that is the basis of ice formation (preventing water from forming ice)

40
Q

Penetrating Cryoprotectant Agents

A

intracellular cryoprotectants with low MWs that permeate the cells

41
Q

Non-penetrating Cryoprotectant Agents

A

extracellular cryoprotectants with high MWs that do not penetrate cells; less probability of being toxic

42
Q

Cell and Tissue Preservation Categories

A
  1. Freese-drying (lyophilization): does not allow effective preservation of primary cells and tissues.
  2. Cryopreservation: allow long term preservation of cells and tissues

3.Hypothermia: allows short term preservation of cells and tissues

43
Q

Lyophilization (Freeze-Drying)

A

removal of ice or other frozen solvents from a material through the process of sublimation (when ice changes directly to a vapor)

44
Q

Lyophilization Steps

A
  1. Freezing - product is completely frozen in a vial or flask and ice crystals form
  2. Vacuum - product is placed under deep vacuum where pressure is lowered
  3. Drying - heat is added to the material in order for water to sublime
45
Q

What 4 parameters should be assessed when determining the toxicity of a cryopreservant

A

type of cryoprotectant
cryoprotectant concentration
time of exposure to cryoprotectant
temperature of exposure to cryoprotectant

46
Q

Slow Cooling Procedure

A

cells are usually cooled in the presence of cryoprotectant at an optimal cooling rate; allows the cells to dehydrate by maintaining equilibrium with partially frozen extracellular solution

47
Q

Purpose of vitrification

A

minimize ice formation/ bypass ice formation entirely

48
Q

Cryopreservation safety and vapor storage

A

storage of samples in liquid nitrogen vapors reduce likelihood of contamination

Cell and Tissue Engineering (6 decks)

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