AJVR, Vol 72, No. 1, January 2011 127 M usculoskeletal injury is a common cause of lame- ness and decreased performance in horses. Use of stem cells is currently being developed and evaluated. However, it has the potential to be a novel efficacious treatment option for a large range of conditions in hu- mans and horses. Stem cells can be characterized as em- bryonic or adult stem cells. Research on adult stem cells has generated excitement about the potential clinical use of these cells because under appropriate conditions, they have the ability to differentiate into a number of Evaluation of equine peripheral blood apheresis product, bone marrow, and adipose tissue as sources of mesenchymal stem cells and their differentation potential Benjamin J. Ahern, BVSc; Thomas P. Schaer, VMD; Shawn P. Terkhorn, PhD; Karen V. Jackson, BVSc; Nicola J. Mason, PhD; Kurt D. Hankenson, DVM, PhD Objective—To evaluate effects of apheresis on mesenchymal stem cells (MSCs) and com- pare those MSCs with MSCs obtained from adipose tissue or bone marrow (BM). Sample Population—Samples obtained from 6 adult horses. Procedures—Samples of blood from a peripheral vein, adipose tissue, and BM aspirate were obtained from each horse. Samples were processed via apheresis of blood and techniques reported elsewhere for adipose tissue and BM. Cultures were maintained until adherence and subsequently were subjected to differentiation protocols to evaluate adipogenic, osteoblastogenic, and chondrogenic potential. Results—Apheresis product had a significantly higher mononuclear percentage, higher platelet count, and lower RBC count, compared with values for peripheral blood. No cell adherence to the tissue culture plates was detected for the apheresis product. Adherence was detected for 6 of 6 adipose-derived and 4 of 6 BM-derived samples. Variations in efficiency were detected for differentiation of adipose- and BM-derived cells into adipocytes, chondrocytes, and osteoblasts. Conclusions and Clinical Relevance—Apheresis was able to concentrate mononuclear cells and reduce RBC contamination. However, the apheresis product was unable to adhere to the tissue culture plates. In matched horses, adipose- and BM-derived MSCs were capable of producing lipids, glycosaminoglycan, and mineral. The BM was vastly superior to adipose tissue as a source of MSCs with osteoblastogenic potential in matched horses. Additional studies will be necessary to optimize apheresis techniques for horses before peripheral blood can be considered a suitable source for multipotential cells for use in cell- based treatments. (Am J Vet Res 2011;72:127–133) different cell types. 1–5 Adult stem cells typically gener- ate the cell types of the tissue in which they reside. For example, hematopoietic stem cells would typically give rise to erythrocytes, leukocytes, and platelets. Other studies 6,7 have revealed that these cells can undergo osteoblastogenesis, adipogenesis, and chondrogenesis. In human medicine, stem cell treatment has been primarily experimental, but stem cells have been used to achieve regeneration of tissues rang- ing from damaged cartilage to bone, muscle, tendon, ligament, and fat. 1–5 In horses, some major injuries and conditions (eg, superficial digital flexor tendi- Received May 22, 2009. Accepted December 15, 2009. From the Department of Clinical Studies–New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348 (Ahern, Schaer); and the Departments of Animal Biology (Terkhorn, Hankenson) and Pathobiology (Jackson, Mason), School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104. Supported by a grant of the Raymond Firestone Trust. This study was performed at the University of Pennsylvania, School of Veterinary Medicine, New Bolton Center. Drs. Ahern and Schaer contributed equally to this report. Address correspondence to Dr. Schaer (tpschaer@vet.upenn.edu). ABBREVIATIONS BM Bone marrow BMA Bone marrow aspiration DMEM Dulbecco minimal Eagle medium FBS Fetal bovine serum GAG Glycosaminoglycan MSC Mesenchymal stem cell PBP Peripheral blood progenitor Unauthenticated | Downloaded 08/28/22 01:51 AM UTC