Platelet Gel- Exam 3 Flashcards
Young, fecund, robust, inactivated platelets are _______ um discoids.
1-3
Humans: Normally how many platelets in blood?
150,000-300,000 / ul of blood
What is the life span of a platelet?
About a week
What do alpha granules contain?
Clotting factors, growth factors, and various other proteins
What do dense granules contain?
ADP, ATP, serotonin, calcium
How do young and old platelets compare?
Young platelets are large and heavy (dense)
Old platelets are small and light
Do young or old platelets aggregate faster? How much faster?
Young large platelets aggregate much faster; about 3-5x faster than older platelets
Do young or old platelets release more ATP? ADP?
Young platelets release more ATP (4-8x more)
Young platelets release more ADP (4-6x more)
Do young or old platelets require substantially greater amounts of ADP to be activated?
Older platelets require more ADP to be activated
What are the 3 phases that occur after tissue injury?
Primary Hemostasis
Secondary Hemostasis
Fibrinolysis
Primary Hemostasis
Vasoconstriction
Platelet adhesion
Platelet aggregation
Secondary Hemostasis
Activation coagulation factors
Fibrin formation
Fibrinolysis
Activation fibrinolytic system
Clot lysis
Fibrinolysis
Activation fibrinolytic system
Clot lysis
Wound –> Exposes what?
Subendothelial Collagen
When subendothelial collagen is exposed, what binds?
von Willebrand Factor
After vWF binds, platelet adhesion to blood vessel wall occurs via what?
Glycoprotein IIb/IIIa receptors
When platelet adhesion to blood vessel wall occurs, what happens next?
Platelet activation
What happens when platelets are activated?
Platelet cytoskeleton (via actin and myosin) expands to form a disc to a multi-pseudopodal sticky blob leading to platelet aggreagation
What does serotonin do?
vasoconstriction
What does ADP do?
Recruits other platelets to aggregate and degranulate
What does thromboxane do?
Platelet aggregation and PGF release
PDGF
Platelet Derived Growth Factor
What does PDGF do?
Strongly mitogenic and chemotactic for leukocytes
By itself, application doubles the rate of collagen deposition in a wound (plus a bunch of tother stuff that aggressively accelerates healing)
TGF-B
Transforming Growth Factor Beta
What does TGF-B do?
Also strongly mitogenic Allows damaged (irradiated, corticosteroid-treated) tissues to revert to normalized collagen deposition
What do attracted neutrophils and macrophages release?
A host of other healing factors
Are granulocytes (neutrophils) good?
Good/bad/indifferent
Where are cells expressing CD34 protein concentrated?
IN the mononuclear layer of platelet concentrate
What are CD34 proteins?
Cells are stem cell “markers” and are important for other cells’ adhesion/chemotaxis
What are CD34 proteins?
Cells are stem cell “markers” and are important for other cells’ adhesion/chemotaxis
What is the source of TGF-B?
Platelets, extracellular matrix of bone, cartilage matrix, activated TH1 cells and natural killer cells, macrophages/monocytes and neutrophils
What does TGF-B do?
Also strongly mitogenic Allows damaged (irradiated, corticosteroid-treated) tissues to revert to normalized collagen deposition
Mesenchymal cell proliferation
Regulates endothelial, firboblastic and osteoblastic mitogenesis
Regulates collagen syntehsis
What is the source of TGF-B?
Platelets, extracellular matrix of bone, cartilage matrix, activated TH1 cells and natural killer cells, macrophages/monocytes and neutrophils
What is the source of Basic Fibroblast Growth Factor?
Platelets, macrophages, mesenchymal cells, chondrocytes, osteoblasts
PRP
Components of whole blood remaining after the removal of most of the red cells; buffy coat
Buffy coat layer
white cells and platelets
PPP
plasma layer without the buffy coat; so you get lots of fibrinogen and coagulation factors but no cells
Platelet Concentrate
Essentially the buffy coat +/- a small (variable ) amount of plasma
Buffy coat = leukocytes + plts
Leukocytes = neutrophils, eosinophils, basophils, macrophages, B and T lymphocytes
Platelet Gel
Platelet concentrate with enough fibrinogen (2-4 mg/ml) to set up when combined with an activator
What is the activator in plt gel?
Thrombin (bovine or human)
Clacium (usually ClC2) or collagen
Platelets 2-6x over baseline
What are the two theories for how many plts you need?
- Increase in multiples above baseline (2-6 x baseline)
2. Absolute numeric concentration (Typically > 1,000,000/ul
What happens when platelets above 6x baseline?
Delays healing; possible up regulation of other tissues to factors in the presence of thrombocytopenia
Platelet gel is used in promoting healing in all tissues except what?
Nervous tissue
Platelet Gel Contraindications
Severe hypovolemia Unstable angine/LM disease Heparin therapy Post-incisional harvest THrombocytopenia (
Where should you NEVER apply plt gel?
Coronary grafts
How many platelets in a “unit” of whole blood?
(Platelets/ul) x 1000 x (ml of whole blood)
How many platelets in a “unit” of PRP?
(Platelets/ul) x 1000 x (ml of PRP)
What is the percent yield of platelets in PRP?
(# platelets in PRP x 100) / (#platelets in whole blood)
What are the two fields of stem cell therapy?
Bone marrow (mesenchymal) derived Adipose derived
Mesenchymal Stem Cells
Generally found in the bone marrow but can be isolated from circulating blood, cord blood, fallopian tubes, and fetal tissue
High capacity for pluropotentiality
High capacity for self renewal
Adipose- Derived Stem Cells
Also a source of multipotential stem cells
>500x more stem cells in 1 gram of fat as compared to 1 gram of bone marrow
Have similar ability to differentiate as does BM derived
Can be extracted without antesthesia/seditive
Avoids fetal stem cell discussion
Stem cells are attracted and stimulated by what?
Activated platelets and the “factors” those platelets produce
Adipose-Derived Stem Cell Extraction Systems
- Remove lipids
- Remove supernatant (saline, phenylephrine, lidocaine)
- Concentrate the adipose stem cells
- Maintain stromal vascular fraction (SVF) which creates a wgood microenvirnment to help promote graft retension
- allow stem cell extract to be mixed asome ratio with platelet concentrate in an aerobic environment
SVF
stromal vascular fraction (SVF)
