Lecture 8-9

Question 1

In order to understand the response of the tissues and the implant to each
other, the critical properties of a typical biomaterial surface that have to be
known are:

Answer 1

 Surface chemistry (i.e., nature of chemical groups and their reactions with
surrounding tissue),
 Topography (the roughness or design),
 Physical (mechanical) properties (i.e., porosity, stiffness)

Question 2

What is selectin?

Answer 2

cell adhesion molecules

Question 3

Cytokines?

Answer 3

small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells

Question 4

Integrin?

Answer 4

Integrins are transmembrane receptors that help cell-cell and cell-extracellular matrix (ECM) adhesion.

Question 5

Uncontrolled proteins adsorbed at…………….

Answer 5

interfaces

Question 6

Leachables:

Answer 6

compounds which can come out of the material when in contact with the body
(in situ testing phase)

Question 7

Effect of Biomaterials on Cells:

Answer 7

-Leachables
-Integrity
-Conformation
-Attachment
-Metabolic Activity and Proliferation
-Differentiation
-Reactivity of the material
-Degradation
-Surface topography and the physical form

Question 8

When a biomaterial is implanted to the body, this procedure damages:

Answer 8

-the vasculature
–the extracellular matrix
-the nerves

Question 9

These all cause:

Answer 9

inflammation(wound healing, foreign body response)

Question 10

First stage of body response to injury:

Answer 10

The sequence starts with coagulation and inflammation as a result of injury (involves both response from blood components and immune
cells) to destroy or inactivate foreign entity and initiate healing.(Immediate,3-5 days)

Question 11

Second stage of body response to injury:

Answer 11

When the foreign entity is destroyed, tissue starts healing: proliferative phase takes over leading to scar tissue formation during
which fibroblastic cells are concentrated to the wound bed and then secrete collagenous extracellular matrix which continuously
replaces the fibrin clot. Around the wound edges, a single layer of cells initially forms over the defect (wound contraction) and
there’s also a marked increase of epithelial cell mitotic activity. The endpoint of migration is when the advancing epithelial cells
meet. After the epithelium reaches maturity, shedding and dispatching of the fibrous clot from the underlying epithelium occurs.
3 days- 3 weeks

Question 12

Third stage of body response to injury:

Answer 12

Finally remodeling takes place to regenerate the injured site and complete the healing process. All unnecessary cells and proteins are
removed via proteloytic enzymes etc. Collagen is remodeled from type III to type I. This new collagen forms, re-organize and
crosslinked by lysyl oxidase to increase mechanical strength of new tissue. The cells that had been used to repair the wound but
which are no longer needed are removed by apoptosis, or programmed cell death.Specialized cells proliferate and form new tissue.
3 weeks  months/years

Question 13

Regardless of the tissue or organ into which a biomaterial is
implanted, the initial inflammatory response is activated by injury to:

Answer 13

vascularized connective tissue

Question 14

What are the components that released during injury?

Answer 14

proteins and blood cells

Question 15

Vasodilation provides:

Answer 15

redness and swelling

Question 16

…………………..(especially………) on foreign surfaces and injured tissues

Answer 16

Adsorption of plasma proteins, fibrinogen

Question 17

What is platelet?

Answer 17

Platelets are the cells that circulate within our blood and bind together when they recognize damaged blood vessels.

Question 18

Platelet binding triggers;

Answer 18

release of storage granule contents to extracellular environment.

Question 19

Granule release increases…………………..on surface and recruits other platelets to site.

Answer 19

receptor expression

Question 20

What is chemotaxis?

Answer 20

Cell migration along a chemical gradient.

Question 21

Platelet aggregation via………………..forms a “…………” initially reduces blood flow.

Answer 21

fibrinogen bridges,plug

Question 22

Complex cascade of enzymatic activity on platelet surface culminates with ……………..of plasma protein……………….to……………..

Answer 22

factor X conversion,prothrombin,thrombin

Question 23

Thrombin cleaves fibrinogen to form insoluble fibrin which ……………. around platelet plug to form the…………..or clot

Answer 23

crosslinks,thrombus

Question 24

Implantation of a biomaterial initiates the inflammatory response:

Answer 24

-response of vascularized tissue to local injury
-severity indicates biocompatibility of material

Question 25

Cooperative Signaling Cascades:

Answer 25

1.Coagulation Cascade
2.Complement Alternative Pathway
(both iniated by adsorbed proteins)

Question 26

3 recognized pathways:

Answer 26

-Classical pathway
-Lectin pathway
-Alternative pathway

Question 27

What is phagocyte?

Answer 27

cells that protect the body by ingesting harmful foreign particles

Question 28

A type of white blood cell

Answer 28

neutrophils(associated with acute inflammatory response)

Question 29

Released products from neutrophils, activated platelets and endothelial cells, along with fibrin, form the …………………..

Answer 29

provisional matrix
(-scaffold for cell attachment
-sustainable release of signaling molecules)