A Comparison of Equine Adipose Tissue, Bone Marrow and Peripheral Blood as Sources of Mesenchymal Stem Cells

Abstract

Lameness is a significant cause of wastage in equine athletes, with reportedly 66% days lost from training being contributed to musculoskeletal injuries. The use of regenerative cell therapies has been suggested as an alternative to current treatments which have low tissue restorative success. Although stem cell treatments are currently utilised, the optimal tissue source of equine mesenchymal stem cells (MSC) for treatment has not been determined.

The aim of the project was to compare the recovery of MSCs from adipose tissue (AT), bone marrow (BM) and peripheral blood (pB). Stem cell characteristics including adherence, proliferation, multipotency, as well as gene expression for stemness and differentiation markers were investigated.

Adipose tissue, bone marrow and peripheral blood samples were isolated from six mares and grown to confluence to investigate MSC yield and proliferation rate. The samples were cryopreserved in liquid nitrogen and then placed into a trilineage differentiation assay to assess tissue-dependent plasticity. Messenger RNA was isolated before and during differentiation to assess changes in gene expression.

All three tissue sources yielded fibroblast MSC-like cells however, AT and BM were found to be superior source of MSCs compared to pB. Trilineage differentiation capacity was demonstrated in AT and BM derived MSCs while peripheral blood derived stem cells were not investigated for multipotency due to a low number of samples. The selected pluripotent ‘stemness’ markers were not widely expressed in any of the three cell types and may not be suitable for use with multipotent stem cells of equine origin. Bone marrow derived stem cells displayed superior expression of differentiation markers compared to adipose derived stem cells.

Adipose tissue was found to be a rich reliable source of MSCs however, this cell source displayed lower efficiency for chondrogenic differentiation. Overall, bone marrow derived stem cells appeared to be a superior source of equine MSCs. An in vivo investigation of treating musculoskeletal injuries with BM and AT derived MSCs is required to determine which source of MSCs offers the best therapeutic benefit for injured horses.