Lecture 3: MSC-Derived Connective Tissue Flashcards

1
Q

Mesenchymal stem cell

A

Progenitor for all resident tissue cells, differentiates from ESC

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2
Q

Basic components of all connective tissue

A
  1. Cells
  2. Fibers
  3. Ground substance
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3
Q

Extracellular matrix

A

Composed of all extracellular parts of connective tissue (fibers + ground substance)

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4
Q

Type II collagen

A

Primary part of hyaline cartilage. Very tight, hydrated ECM that makes cell motility impossible.

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5
Q

Type I collagen

A

Dominant large fiber of CT. Forms ropes/sheets for structural and space-filling roles as procollagen linked into fibrils. More type I = more density

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6
Q

Hydrogels

A

Bioengineered compounds that mimic CT properties

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7
Q

Mesenchymal stem cell

A

Progenitor cell for all stromal cells of CT compartments (adipocytes, fibroblasts, muscle)

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8
Q

Unilocular adipocytes

A

Also known as white fat cells occur in white adipose tissue and primarily act as energy storage. Will often undergo hypertrophy instead of dividing.

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9
Q

Multilocular adipocytes

A

Also known as brown fat cells, occurring in brown adipose tissue. Specialized for thermogenesis.

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10
Q

Beige fat cells

A

Transitional stage between from white fat to brown fat. Multilocular thermogenic cells found in white adipose tissue

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11
Q

Fat depots

A

Areas of white fat collections, e.g. the subcutaneous, visceral, and intermuscular fat.

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12
Q

Fibroblasts

A

Cells responsible for production, remodeling, and degradation of ECM fibers and ground substance

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13
Q

Myofibroblasts

A

Myosin-producing fibroblast subtype. Responsible for generating force, e.g. in wound closure

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14
Q

Type III collagen

A

Dominant small fiber of CT and in the mesenchyme (embryonic undifferentiated CT). Provides support in regions with more cells. More type III vs type I typically makes looser CT. AKA reticular fibers

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15
Q

Elastin

A

Main protein in elastic fibers, along with some fibrillins. Provide stretchiness in CT.

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16
Q

Type IV collagen

A

Forms the lamina densa of external/basement membranes

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17
Q

Type VII collagen

A

Forms anchoring filaments in lamina reticularis of external/basement membranes

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18
Q

Type X collagen

A

Supportive role necessary for deposition of type I collagen at bone growth plates

19
Q

Type V collagen

A

Necessary for fibrillation of type I and III collagens.

20
Q

Classes of fibrous CT

A
  1. Loose
  2. Dense irregular
  3. Dense sheet-like
  4. Dense regular
21
Q

Loose connective tissue

A

Contains a higher proportion of type III collagen and ground substance. Fibers have irregular orientation, fills layers that allow cell motility and also loose-cell-ball organs e.g. spleen, lymph nodes

22
Q

Dense irregular connective tissue

A

Mostly type I collagen arranged in 3 dimensions; default space-filling CT. Generally does not allow cell motility (but density is on a spectrum).

23
Q

Dense sheet-like connective tissue

A

Mostly type I collagen arranged in 2D sheets. Compartmentalization of CT like bones, joints - forms sheaths and fascia

24
Q

Dense regular connective tissue

A

Mostly type I collagen aligned in 1 dimension. Highly regulated development via other collagens and mostly only found in tendons/ligaments.

25
Q

Matrix metalloproteases (MMPs)

A

Class of compounds that degrade collagens, elastins, and other CT parts. Some are specific to collagen type.

26
Q

Ground substance

A

Occupies space between CT cells and fibers. Consists of highly hydrated proteoglycan complexes and glycoproteins

27
Q

Proteoglycan

A

Large molecule with backbone (e.g. hyaluronic acid), proteoglycan stems, and glycosaminoglycans (GAGs) with associated water molecules

28
Q

Peri-neuronal nets (PNNs)

A

EC proteoglycan structure that surrounds neurons. Guide/deter the growth trajectory of new axons and formation of new connections.

29
Q

Examples of glycosaminoglycans

A

Dermatan sulfate, heparan sulfate, keratan sulfate, chondroitin sulfate

30
Q

Matrisome

A

The entire ECM of the CT in a given location

31
Q

Matrisome core components

A
  1. ECM glycoproteins (non-fibrillar proteins)
  2. Collagens
  3. Proteoglycans
  4. Associated proteins, regulators, secreted factors
32
Q

Cellular CT disorders

A

Often immune-mediated; e.g. immune responses can reduce the fibrous fraction and weaken CT walls

33
Q

Fibrous CT disorders

A

Fibroproliferative responses, e.g. cysts, loss of flexibility, keloid scars, organ LOF due to scarring. Some genetic fiber disorders e.g. Marfan

34
Q

Ground substance CT disorders

A

Imbalance of fluid flow can lead to edema. Caused by occlusion of fluid drainage or inadequate circulation.

35
Q

Uncoupling protein

A

UCP-1 determines if fat will be thermogenic; changes mitochondria product from ATP to heat

36
Q

CT origin

A

Mesoderm layer. After folding, mesoderm comes to fill space between ectoderm (outside) and endoderm (gut tube)

37
Q

Trans-differentiation

A

Conversion of one cell type to another, e.g. adipocytes <-> muscle <-> fibroblasts

38
Q

De-differentiation

A

Process by which cells become less specialized and return to earlier state in lineage, e.g. adipocyte/fibroblast/muscle -> MSC

39
Q

Adipocyte hypoxia

A

Adipocyte hypertrophy can outgrow oxygen supplies, leading to cell death and inflammation; may mediate many obesity-related disorders.

40
Q

Highly fluid CT

A

Blood and lymph are examples of highly fluid and cellular CT, low in fibers

41
Q

Highly fibrous CT

A

Tendons and ligaments are examples of highly fibrous CT, with low cells (and low cell motility) and lower ground substance

42
Q

Functional classes of collagen

A
  1. Fibrillar (Type I, II, III)
  2. Fibrillar anchoring (Type VII)
  3. Meshwork (Type IV)
  4. Other nonfibrillar (many)
43
Q

External membrane

A

Membrane that surrounds adipose and muscle tissue

44
Q

Basement membrane

A

Membrane on basal side of epithelia (always have polarity). External = basement when epithelium is attached.