Speaker
Description
"Introduction
We have derived horse embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Pluripotent stem cells undergo unlimited self-renewal and can differentiate into every tissue of the body; properties which can be utilised for therapeutic applications and disease modelling.
We have investigated their application in tendon injuries and catastrophic bone fractures, conditions that have major welfare and economic impacts on equine industries. Tendon injuries are a leading cause of retirement in horses taking part in a range of disciplines and catastrophic fracture is the number one reason for euthanasia during Thoroughbred racing.
Adult tendon injuries repair through scar tissue formation which predisposes horses to high rates of re-injury and novel therapies to aid tendon regeneration are required. Equine ESCs turn into tendon cells following their injection into the injured tendon1 and we have established 3D in vitro culture methods2 to define their properties and compare them to adult cells.
The risk of catastrophic fracture is influenced by environmental and genetic factors. A better understanding of the genetic risk factors would enable improved identification and management of high risk horses. Equine iPSCs can be derived from horses with different genetic backgrounds. This has allowed us to establish an in vitro model3 to understand the genetic basis of catastrophic fracture risk.
Methodology
We have established protocols to differentiate ESCs and iPSCs into tendon and bone (osteoblast) cells using both 2D and 3D culture methods.
Global gene expression profiling using RNA sequencing has been used to make comparisons between ESC-derived, adult- and fetal-tenocytes, and between iPSC-osteoblasts derived from horses at high and low genetic risk of fracture.
Other properties of ESC-tenocytes such as cell migration and response to inflammation have also been measured. Molecular biology techniques to understand the impacts of DNA variants associated with fracture are also being used.
Results
We have demonstrated that ESC-tendon cells more closely resemble fetal than adult tenocytes4 but that they have properties that are unique to them, such as resistance to inflammation5 and unpublished data.
iPSC-osteoblasts taken from horses at high and low risk of fracture were found to have 112 differentially expressed genes. Some of which have known roles in bone formation or fracture. Pairing gene expression information with whole genome sequencing data allows us to identify putative causal single nucleotide polymorphism (SNPs) that may be responsible for these differences and we highlight results for COL3A1 that demonstrate the power of this approach.
Conclusions
Pluripotent stem cells from horses not only provide a source of cells for potential therapeutic use, but they can also be used for disease modelling. They therefore hold great promise to allow the future development of novel interventions and therapies.
References
1. Guest, D.J.et al. Equine vet. J., 2010. 42(7): p. 636-642.
2. Barsby, T., et al. Tissue Eng Part A, 2014. 20: p. 2604-2613.
3. Baird, A., et al., Biology Open, 2018. 7(5): p. bio033514.
4. Paterson, Y., et al., Mechanisms of Development, 2020. 163: p. 103635.
5. McClellan, A., et al., Sci Reports, 2019. 9(1): p. 2755."
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