Human liver scaffolds
This invention relates to methods for decellularising human liver tissue to produce human hepatic extracellular matrix (ECM) scaffolds, for example for use in therapy or disease modelling. The methods involve mechanically damaging cells in the tissue, for example by freeze thaw, and then subjecting the liver tissue to multiple cycles of osmotic stress, detergent treatment and protease and/or DNAase treatment to produce a decellularised human ECM scaffold.
1. A method of producing a decellularized human liver scaffold comprising
(i) providing healthy or pathological human liver tissue comprising a whole liver or a functional unit thereof,
(ii) mechanically damaging the cells in the tissue,
(iii) subjecting the cells in the tissue to osmotic stress by exposing the tissue to a hypotonic reagent or hypertonic reagent,
(iv) exposing the tissue to a protease and/or DNAase, and
(v) exposing the tissue to a detergent, and
(vi) repeating steps (iii) to (v) in the following sequence by perfusion through the liver tissue: (iii), (iv), (iii), (iv), (v), [(iii), (v)] n , optionally [(iii), or (iv)], [(iii), (v)] n , where n is independently 1 to 25;
thereby producing a decellularized human liver scaffold,
wherein the human liver tissue is subjected to flow shear stress generated by perfusing the human liver tissue in a retrograde direction with the hypotonic reagent, hypertonic reagent, protease and/or DNAase, and detergent during steps (iii) to (vi) at a perfusion rate which increases from an initial value of 0.1-1.99 ml/min/gram of tissue and stabilizes to a target value of 2-20 ml/min/gram of tissue.
2. A method according to claim 1 wherein the cells are mechanically damaged by subjecting the tissue to one or more rounds of freezing and thawing, or by subjecting the tissue to high intensity focused ultrasound (HIFU) or sonication.
3. A method according to claim 1 wherein the hypotonic agent is deionised water.
4. A method according to claim 1 wherein the tissue is exposed to a trypsin or pronase in step (iv).
5. A method according to claim 1 wherein the detergent is an anionic detergent.
6. A method according to claim 5 wherein the anionic detergent is sodium dodecyl sulfate (SDS) or sodium deoxycholate (SdC).
7. A method according to claim 1 , wherein the detergent is a non-ionic detergent, and is polyethylene glycol p-(1, 1, 3, 3-tetramethylbutyl)-phenyl ether (Triton X100™).
8. A method according to claim 1 wherein the liver tissue is subjected to a perfusion regime as set forth below:
DAY
Steps and Reagents
DAY −1
Thaw the liver o.n. at 4° C.
DAY 0
dH2O
0.025% Trypsin/EDTA
DAY 1
dH2O
0.01% SDS
0.1% SDS
1% SDS
DAY 2
dH2O
0.025% Trypsin/EDTA
1% SDS
DAY 3
dH2O
3% TX100
DAY 4
dH2O
3% TX100
DAY 5
dH2O
3% TX100
DAY 6
dH2O
3% TX100
DAY 7
dH2O
0.025% Trypsin/EDTA
DAY 8
dH2O
1% SDS
DAY 9
dH2O
1% SDS
DAY 10
dH2O
1% SDS
DAY 11
dH2O
1% SDS
DAY 12
dH2O
1% SDS
DAY 13
dH2O
PBS/Antib-Antimic 5%
3% TX100
DAY 14
dH2O
PBS
PBS/Antib-Antimic 5%
dH2O
0.1% PAA/4% EtOH
PBS.
9. A method according to claim 1 comprising sterilising the scaffold following decellularisation.
10. A method according to claim 1 comprising re-populating the decellularized human liver scaffold with cells to produce artificial liver tissue.
11. A method according to claim 10 wherein the cells are selected from the group consisting of human primary and cell line liver cells, human primary hepatocytes, human endothelial cells, human induced pluripotent stem cells (iPSCs) or cells derived from patient-specific iPSCs, human embryonic stem cells (hESCs), human mesenchymal stem cells (hMSCs), human fetal stem cells, human cancer cells and human endothelial progenitor cells (EPCs).
12. A method according to claim 1 , further comprising:
providing a sample of the decellularized human liver scaffold, wherein the human liver tissue was obtained from a healthy or pathological human liver, and
determining the presence and amount of one or more liver scaffold proteins in the sample.