33rd Annual Scientific Meeting proceedings

Introduction
Autologous conditioned serum (ACS) is a commonly used orthobiologics and clinical effect is related to levels of IL-1Ra and IGF-1. Serum incubation in vacutainer tubes has shown similar cytokine levels as incubation in specialized ACS tubes containing glass beads.

Objective
Compare cytokine levels in equine serum after incubation in three different tubes.

Study design
Experimental in vitro study.

Methods
Blood was aseptically drawn from 15 healthy horses and incubated at 37˚C for 22-24 hours in a commercial ACS container (COMM); a 50 ml sterile plastic centrifuge tube (CEN), and in 10 ml plastic vacutainer tubes (VAC). The concentration of IL-1β, IL-1Ra, IL-10, IGF-1 and PDGF-BB was determined by ELISA and compared between methods using a mixed model with tube/method as fixed effect and horse as random effect.

Results
There was no difference in concentration of IL-1Ra and IGF-1 between CEN and COMM. PDGF-BB was higher in CEN vs. COMM (P < 0.0001). IL-1Ra and PDGF-BB was higher (P < 0.005 and P = 0.02, respectively) whereas IGF-1 was lower in VAC (P < 0.003) vs. the other 2 methods. IL-1β was below the detection limit in all samples.

Conclusions
The 50 ml sterile centrifuge tube performed similarly to, and even better, than the commercial ACS tube in cytokine enrichment and has the potential to dramatically reduce the cost of ACS treatment. This tube also resulted in a cytokine profile presumably more beneficial than incubation in vacutainer tubes. Cytokine enrichment of ACS does not require the presence of glass beads.