Comparison of isolation and expansion techniques for equine osteogenic progenitor cells from periosteal tissue

Stem cell therapy and cell-based therapies using other progenitor cells are becoming the treatment of choice for many equine orthopedic lesions. Important criteria for obtaining autogenous equine progenitor cells in vitro for use in clinical cell-based therapy include the ability to isolate and expand cells repeatedly to high numbers (millions) required for therapy, in a clinically relevant time frame. Cells must also maintain their ability to differentiate into the tissue type of choice. The objective of this study was to compare isolation and expansion techniques for preparation of periosteal-derived osteogenic progenitor cells for use in commercial autogenous cell-based therapy. Cells were allowed to migrate spontaneously from periosteal tissue or were enzymatically released. Isolated cells were expanded using enzymatic detachment of cells and subsequent monolayer or dynamic culture techniques. Viable osteogenic progenitor cells from each group were counted at 2 weeks, and osteogenic potential determined. Cells isolated or expanded using the explant or bioreactor technique yielded cells at a much lower number per gram of tissue compared with that of enzyme digestion and monolayer expansion, but all cells were able to differentiate into the ostoblast phenotype. Osteogenic progenitor cells isolated by enzymatic release and expanded using monolayer culture reached the highest number of viable cells per gram of donor periosteal tissue while maintaining the ability to differentiate into bone forming cells in vitro. This technique would be an easy, consistent method of preparation of equine osteogenic cells for clinical cell based therapy for orthopedic conditions.