ABM CDT Development of a 3D osteochondral tissue model to further understand the molecular impact of the genetic risks in osteoarthritis

Osteoarthritis (OA) is a common, complex disease, where both genes and the environment have a role in disease risk and development. OA is the most common form of arthritis and is increasing in prevalence. Treating OA cost the NHS £10.2bn in 2018, the 4th largest NHS spend. There is currently no cure for OA, and novel treatment targets are urgently required.

Despite genome wide association studies (GWAS) identifying 100 robust loci for OA disease susceptibility, there remain no clinically-proven therapeutic interventions to alter the course of the disease. There is therefore an urgent requirement to better understand the genetics of OA, in terms of the genes that are perturbed, the cell types they affect and the resulting phenotypic change.

Recently advances in molecular biology, in the form of CRISPR gene engineering, have allowed for insights into complex disease biology. The vast majority of genetic changes that increase the risk of OA are to be found in cell type and context specific gene regulatory elements. By utilising a suite of CRISPR techniques we can now perturb the risk DNA variants and measure the downstream affects.

Currently these techniques are performed in monolayer and typically in single cell culture. Whilst these conditions give useful information, creating a 3D tissue construct that allows for biomimicry of the 3D environment will greatly improve our understanding of the genetic risks in osteoarthritis.

This project will bring together the genetic and molecular approaches to understanding and therefore potentially treating OA by Professor Eyre and Dr Orozco with the 3D osteochondral tissue engineering strategies developed in Professor Cartmell’s laboratory.

By bringing together the advances in genome editing and biomaterials, there is now the opportunity to understand the genetic mechanism of increased risk of OA, leading to novel therapeutic targets, biomarkers of disease and stratified medicine. 

Questions to be answered:

Main research question: What effect do genetic variants associated with risk of OA have at the molecular, cellular and tissue level?

This will be examined in 3D cell culture systems with all the relevant cell types, including osteoblasts, osteoclasts and chondrocytes.

CRISPR will be performed in the cell types to either change the DNA from risk to non-risk, or stimulate/inhibit the affected regulatory region. 3D cell cultures will then be employed to assess the effect of these changes in terms of gene expression, protein expression and tissue performance (e.g., strength).

Professor Cartmell already has two co-culture systems developed – conditions needed for osteoblast/osteoclast coculture, and conditions needed for osteoblast / chondrocyte coculture in a 3D tissue engineered bioreactor system. This project will incorporate both culture systems together using additive manufacturing approaches.

This project will use a variety of biomaterial scaffolds to create the 3D tissue coculture system being developed for OA analysis.

The student initially will investigate the best scaffolds to use for the coculture system. For the bone section we will compare salt leached polylactic acid, spongostan hemostatic sponge and also source human freezer dried trabecular bone as a scaffold for the osteoblast / osteoclast coculture.