title: Aspiration, but not injection, decreases cultured equine mesenchymal stromal cell viability.
abstract: BACKGROUND
  Recently, equine multipotent mesenchymal stromal cells (MSC) have received significant attention as therapy for various conditions due to their proposed regenerative and immune-modulating capacity. MSC are commonly administered to the patient through a hypodermic needle. Currently, little information is available on the effect of such injection has on equine MSC immediate and delayed viability. We hypothesize that viability of equine MSC is not correlated with needle diameter during aspiration and injection.
  
  
  RESULTS
  Using a 3 mL syringe, manual injection of equine cord blood (CB) or bone marrow-derived (BM) MSC with no needle and needles ranging in size from 18 to 30 Ga did not affect immediate MSC viability. Similarly, 24 h post-injection, MSC delayed viability was not different between any of the tested needles as determined by a resazurin-based proliferation assay. Using a 3 mL syringe, aspiration of MSC through 20, 25, and 30 Ga needles resulted in significant decreases in immediate viability with no change in delayed viability when compared to aspiration without a needle. BM- and CB-MSC were observed to be of similar size with a diameter ± SD of 19.8 ± 2.7 and 20.4 ± 2.2 μm, respectively. In comparison, the smallest needles, (30 Ga) have an internal diameter of 160 μm.
  
  
  CONCLUSIONS
  Following injection, needle diameter did not affect immediate or delayed viability of equine MSC. Following aspiration through needles sizes 20 Ga and smaller, immediate viability, but not delayed viability, decreased. As a result, an 18 Ga or larger needle should be utilized for aspiration of cell suspensions. In contrast, needle selection for MSC injection should be based on clinical preference and experience rather than concerns over decreasing MSC viability.
authors.affiliation: Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada. williamsdvm@gmail.com.
authors.forename: Lynn B
authors.initials: LB
authors.lastname: Williams
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada. krusse05@uoguelph.ca.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Russell
authors.affiliation: Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada. jkoenig@uoguelph.ca.
authors.forename: Judith B
authors.initials: JB
authors.lastname: Koenig
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada. tkoch@uoguelph.ca.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Koch
mesh_terms: D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D006736:Horses; D007267:Injections / Q000295:instrumentation / Q000379:methods; D059630:Mesenchymal Stem Cells; D009339:Needles