lecture 11

Question 1

What are the clinical drivers behind tissue engineering?

Answer 1

End stage organ failure or tissue loss
Donor transplantation 
Inadequate supply
Increasing demand - ageing population
Long term immunosuppression 
Clinical need for new approaches
Extended range of tissues/organs
Immunocompatible or (better) autologous

Question 2

Describe urinary bladder structure and function

Answer 2

Capacity and compliance
Storage of urine until appropriate to void
One way flow (no reflux)
Low (kidney-sparing) pressures
Innate defence against UTI
The urinary bladder has to store urine until it’s time to urinate - functions by collecting the urine from the kidneys, and is able to expand to collect a large volume of urine without an increase in pressure. This is important because if there was a high pressure bladder this would create retrograde pressure on the kidneys, which are very sensitive organs (can’t regenerate itself).There must be one-way flow of urine - backflow may take bacteria and other things up to the kidneys, causing kidney infection. The bladder has a innate defense mechanism, and is able to respond to any bacteria which enters the bladder through the production of antimicrobials - very efficient system.
Urine is kept in the lumen of the bladder, and this is lined with the urothelium. Beneath this urothelium is a stromal tissue with a collagenous matrix, which is very compliant to allow the bladder to fill under low pressure. Beneath this is smooth muscle wall which is very thick and involved in relaxing as the bladder fills and contracting as it empties.

Question 3

What’s bladder extstrophy

Answer 3

Rare congenital anomaly in 1 per 10,000 to 50,000 live births; 2:1 male:female ratio.
failure of the abdominal wall to close during fetal development
Results in protrusion of the anterior bladder wall through the lower abdominal wall.
Surgical reconstruction, but long term problems
bladder on outside of body

Question 4

What is Enterocystoplasty

Answer 4

Once medial interventions have failed, surgeons currently carry out enterocystoplasty - base of neuropathic bladder is removed and then the bowel is used to reconstruct it. Excised bowel segment, still attached to vascularisation is reconfigured to form a pouch which is used to then reconstruct the bladder.

Question 5

What is Enterocystoplasty

Answer 5

Once medial interventions have failed, surgeons currently carry out enterocystoplasty - base of neuropathic bladder is removed and then the bowel is used to reconstruct it. Excised bowel segment, still attached to vascularisation is reconfigured to form a pouch which is used to then reconstruct the bladder.
Combined with intermittent self-catheterisation
Low pressure kidney-protective reservoir
Provides continence, capacity & compliance
But major clinical complications
Bowel epithelium is mucus producing = stones & infection
Absorptive not barrier epithelium = metabolic disturbances
Potential cancer development risk
There is a long-term risk that the interaction of the urine with the absorptive nature of the bowel can lead to cancer. Any engineering-based therapies developed must be better than this.