4 Reg Med

What may be required for effective maturation invitro

different physical (and chemical) cues

What are some examples of different physical (and chemical) cues?

O2 concentration, fluid flow, forces

How can effective maturation invitro be achieved?

bioreactors

Simple mechanism of bioreactor?

Magnetic stirrer bar that moves medium around → medium flows over through the scaffold

What does mechanical stimulation help with in bioreactors?

• helps nutrients get into the cells
  Get rid of waste
  Shear forces and flow stimulate cell growth

What are the features of a Rotary cell culture?

• Gravity and the force of the rotation balance each other out

• Get scaffold with the cells on it floating in simulated microgravity

• Gentler on the cells

Describe compression bioreactors?

• the cells and the scaffold

  Apply for a certain and specific times to mimic natural environment and then let the cells rest

  Bone tissue

Why may the cells in a bioreactor need to be under tension?

• Muscle → forces in the axis tension

• Cells will line up along that axis of tension

What are is the study data and the future possibilities of bioreactors

• Bioreactor culture increased cell proliferation and bone matrix formation in comparison to static

• Patient-specific bone constructs a possibility using this technique

How would body bioreactors work?

• Correct environment for tissue development – chemical signaling, mechanical forces, etc.

• Insert scaffold into the host and let its body do the work

• Calcium alginate hydrogel injected between periosteum and tibia in rabbits to create an “in vivo bioreactor”

Why may acellular strategies have advantages over engineered tissues?

• Can be designed to release cocktails of small and macromolecular drugs and to recruit specific cells.

• Cardiac cells → to repair damage following MI

How were application of bioreactors used in bronchial repair?

Decellularised donor trachea
Seeded with epithelial cells from patient and MSC

to produce the cartilage around the bronchus
No donor antibodies and no immunosuppressive drugs

How could hearts be engineered to help the complexity of scaffold?

• Using decellularized hearts as scaffolds

  • Right size and shape in order to grow the cells

  • In matrix still have the structure of the blood vessels in the heart along with other structure

  • Could use xenogeneic tissue

How were decellularised kidneys in scaffolds

• hiPSCs were used to generate endothelial cells

• Infusion into renal artery of decellularized kidney resulted in uniform distribution of hiPSC-ECs in all vascular compartments - 89% coverage of glomeruli

• Cells were continuous along vessel walls

• Site-specific specialization apparent – fenestrations in endothelium of glomerular capillaries → reformation

Why are blood vessels an issue when produces scaffold and engineered tissues?

Cells need to be within ~200 µm of a blood vessel to survive in the body – tissue engineered constructs need capillaries which integrate with the patient

What are the 3 solutions for the vascular issue with scaffolds and engineered tissues?

1. Seed scaffold with endothelial cells - randomly or using pre-formed channels

2. Incorporate VEGF into scaffold → existing endothelial cells will be stimulated and form vessels that stimulate the tissues

3. Build scaffold around vascular bed ex vivo

What does blood contain that could help the vascular issue with scaffolds and engineered tissues?

contain many proteins → promote the formation of blood vessels - e.g. PDGF, VEGF, FGF-2
endothelial progenitor cells → can form blood vessels when stimulated - e.g. Endothelial Colony Forming Cells (ECFCs)

How could blood contents be applied to help the vascular issue with scaffolds and engineered tissues?

• Form a gel with the platelet rich plasma with endothelial cells in it

  • Have tissue specific cells as well

    • Forming the tissue with the blood vessels in it

  • Implant it into the patient, growth factors within this gel stimulate the infiltration of vessels from existing endothelial cells in the patient to infiltrate and join together

What is the potential of blood contents in the vascular issue with scaffolds and engineered tissues?

platelet lysate and ECFCs offers a ready made, vessel-containing scaffold for engineering many tissue types
Growth factors in the gel will stimulate the patient’s existing vessels to integrate

All materials from the patient, so no rejection or disease transmission problems

What is the problems with biorprinting?

• Cell density

• Resolution

• Vascularization

• Innervation

• Mechanical integrity

5 body parts that can be 3D printed?

1. Blood vessels

2. Heart valves

3. Skin

4. Liver cells

5. Bionic ear

Also: Cartilage

What does Myoseverin do?

Turns cells in to mononuclear cells

What does Reversine do?

turns cells into stem cells

Where could regeneration be used?

Possible Diabetes Treatment
Activating Quiescent Stem Cells
Reactivate to repair

• Niche → becomes more inflammatory and less proliferative → less activated

What have studies shown in chemical regeneration

• Six chemical cocktails identified which can reverse cellular ageing in less than a week

• Other studies have shown that cell can be partially reprogrammed in vivo to reverse ageing and promote regeneration

• Reprogramme cells within the body to reverse aging → promote regeneration

  • Possibly with small molecules