Blood Brain Barrier Extra Reading

Question 1

How are spherical liposomes synthesised in comparison to nano rods.

Answer 1

Nanorods are produced by direct chemical synthesis: ligands are combined to act as shape control agents and they bond to different facets of the nanorod with variable strengths. This allow different faces of the system to grow with different rates and a final elongated object is obtained.

Liposomes are manufactured either by solvent evaporation, solvent dispersion (Section 2.1. 2) or reverse phase evaporation technique (Section 2.1. 3) using ammonium sulphate solution as the aqueous phase.

Question 2

How much antibody get into the brain.

Answer 2

<0.1%

Question 3

Describe the pathophysiology of Alzheimer’s Disease.

Answer 3

Alzheimer’s is an insidious, progressive, degenerative disease. The disease progresses in centrifugal way from hippocampus to areas of the brain such as pre-frontal cortex. The symptom manifestation are reflection of the progression of the disease such as dementia resulting to damage to hippocampus to impairment of executive function due to damage at prefrontal cortex. Amyloid plaques and neurofibrillary tangles are implicated.

Question 4

What is the concentration of albumin, potassium, glutamate in the brain extracellular fluid.

Answer 4

Albumin: 0.02 g/dL
Cholesterol: 0.2 mg/dL
Glutamate: 0.05 micromoles.

Question 5

Using the acronym You Will Know please list the research findings of each antibody related therapy.

Answer 5

Question 6

Which drug delivery system can use adsorptive and receptor mediated transcytosis.
(a) Nanoparticle: scL-p53
(b) Nanoparticle: Angiopep-2/paclitaxcel
(c) Nanoparticles: PEG-ylated+lipopetide/Angpep2
(d) Bi-specific trojan antibody

Answer 6

(c) Nanoparticles: PEG-ylated+lipopetide/Angpep2

Question 7

Which drug delivery system showed increased uptake after 6 hours post-injection.
(a) Nanoparticle: scL-p53
(b) Nanoparticle: Angiopep-2/paclitaxcel
(c) Nanoparticles: PEG-ylated+lipopetide/Angpep2
(d) Bi-specific trojan antibody
(c) Nanoparticles: PEG-ylated+lipopetide/Angpep2

Answer 7

(a) Nanoparticle: scL-p53

Question 8

Which drug delivery system showed increased uptake after 6 hours post-injection.
(a) Nanoparticle: scL-p53
(b) Nanoparticle: Angiopep-2/paclitaxcel
(c) Nanoparticles: PEG-ylated+lipopetide/Angpep2
(d) Bi-specific trojan antibody
(c) Nanoparticles: PEG-ylated+lipopetide/Angpep2

Answer 8

(a) Nanoparticle: scL-p53

Question 9

After X amount of months brain shuttle antibody (anti-amyloid/TfR) showed decrease in amyloid plaques.
(a) 4 months
(b) 6 months
(c) 2 months
(d) 3 months

Answer 9

(a) After 4 months.

Question 10

After X amount of hours the bispecific antibody (TfR/BACE) accumulated more in the brain than plain therapy.
(a) 13 hours
(b)16 hours
(c)12 hours
(d)5 hours

Answer 10

(c)12 hours.

Question 11

How did amyloid in brain decrease with the use of bispecific antibody.

Answer 11

By the bispecific antibody binding to BACE-1 enzyme inhibiting the synthesis of amyloid.

Question 12

Which drug delivery system was tested in cynomogulus monkey.
(a) Bispecific antibody
(b) Brain shuttle
(c) Antibody vehicle transport

Answer 12

(c) Antibody vehicle transport

Question 13

After X amount of hours there was more YFab then ZFab.

Answer 13

After 24 hr amount of hours there was more sFab then dFab.

Question 14

Which therapy saw reduction in amyloid after 24 hours.
(a) Bispecific antibody
(b) Brain shuttle
(c) Antibody vehicle transport

Answer 14

(a) Bispecific antibody.

Question 15

Which therapy saw reduction in amyloid after 4 weeks
(a) Bispecific antibody
(b) Brain shuttle
(c) Antibody vehicle transport

Answer 15

(c)Antibody vehicle transport

Question 16

Which therapy saw reduction in amyloid plaque after 4 months
(a) Bispecific antibody
(b) Brain shuttle
(c) Antibody vehicle transport

Answer 16

(b) Brain shuttle

Question 17

What is the disadvantage of PEG-coated nanoparticle.

Answer 17

The drawback of PEGylation is limited uptake in targeted cells and hindering of endosomal escape following uptake (Bruun 2015).

Question 18

How would you solve the PEGylation dilemma

Answer 18

Conjugation of PEG to the nanoparticle through labile linkers, such as disulfide bonds, pH-sensitive groups, or esterase-sensitive groups. One class of tumor-specific enzymes that particularly have been exploited for in situ activation of drug delivery vehicles is matrix metalloproteinases due to its greater expression in tumour site.

Question 19

Which finding is true for ANG-NP by Xin et al.
(a) Tumour volume decreased (14 day treatment)
(b) Tumour volume decreased after 14 days.
(c) Tumour volume decreased after 10 days
(d) Glioma tumour volume slowed down for the first 10 days only (cm3 vol).

Answer 19

(a) Tumour volume decreased (14 day treatment)

Question 20

Which finding is true for scL-p53 by Kim et al.
(a) Tumour volume decreased (14 day treatment)
(b) Tumour volume decreased after 14 days.
(c) Tumour volume decreased after 10 days
(d) Glioma tumour volume slowed down for the first 10 days only (cm3 vol).

Answer 20

(d) Glioma tumour volume slowed down for the first 10 days only (cm3 vol).

Question 21

Which one after 6hr showed levels of drug in the tumour.
(a) scL-p53
(b) LRP-NP chemotaxis
(c) RMT+AMT-NP
(d) ANG-NP

Answer 21

(a) scL-p53

Question 22

What was the charge switch experience by the RMT (LRP) +AMT-NP
(a) +7 mV- -2 mV
(b) -7 mV - -2 mV
(c) -7 mV - +2 mV
(d) +7 mV - +2 mV

Answer 22

(c) -7 mV - +2 mV

Question 23

What is the % failure rate for treating neurodegeneration and brain tumours.

Answer 23

99.6% failure rate Cumming et al 2014.

Question 24

What are the gaps/difficulties in delivering drugs to the brain.

Answer 24

Local delivery of drug relies on blood flow to the area—> determined by the neurovascular unit and nerve activity. Dead neurones or astrocyte= result low blood flow.
Inter-patient variability with their expression CYP enzymes and transport proteins depending on lifestyle and drug intake: alcohol, smoking and pollutants are all substances that can induce the expression of more CYP/transport proteins.
CNS resistance seen with drugs administered by expression of transporter proteins.

Question 25

What other ways could you enter into the BBB

Answer 25

Virus-mediated blood brain delivery- safety issues, crossing BBB at high dose by IV administration .

Question 26

What are the difference between rodent BBB and human BBB and how will it affect delivery of drug to the brain.

Answer 26

Difference in P-gp activities in human and rodent blood-brain barrier which will effect the efficacy and safety profile of any drug. BBB expression of P-gp activity is reportedly lower in humans compared to mouse and rate and subject to an age-dependent increase. Might complicate animal to human extrapolation of brain drug dispostion and toxicity especially in children with glioblastomas.
Some studies have described differences in amyloid-beta clearance across mouse and human.

Question 27

What are the limitations of bispecific antibody.

Answer 27

Relatively unstable compared to the other antibodies discussed and thus means it is likely to be given as continuous infusion due to instability.

Question 28

What is benefit of delivering antibody to brain (give only 2 reasons).

Answer 28

Circumvents the metabolic and physical barrier.
Too large to be cleared by the blood-CSF-barrier.

Question 29

What is the limitation of the brain shuttle antibody.

Answer 29

Large molecular weight because adding to already large macromolecule.