Three-dimensional tissue culture supports the structure and function of equine synovial explants over 4 days

To evaluate the feasibility of short-term 3-D tissue culture in maintaining the structure and function of equine synovial explants and demonstrate that day 4 explant characteristics were not significantly different from day 0. We hypothesized that a 4-day culture period in 3-D explant culture would not significantly disrupt synovial tissue health and function compared to baseline measurements.

Synovial explants (n = 24/horse) from healthy carpal joints of 5 horses were cultured in 12-well plates using tissue-stabilizing agar rings. Explants were evaluated in triplicate or quadruplicate at days 0, 2, and 4 for metabolism, viability, histologic parameters, cytokine secretion, and hyaluronic acid production.

No tested parameters showed significant changes by day 4. Average cell viability was 87.99% (95% CId4-d0, -4.6% to 12.99%), and histologic grading showed slight but nonsignificant changes. Mitochondrial NADH production from pyruvate and malate on day 4 remained at 85% to 90% that of day 0 (Cohen d, 0.184, 0.153). Hyaluronic acid production over days 2 to 4 was 95.98% that of days 0 to 2 (95% CIday4/day2, 73.82% to 118.14%). Cytokine secretion showed nonsignificant decreases (TNFαday4/day2, 0.518; CI, 0.159 to 0.417; IL-1βday4/day2, 0.520; CI, 0.150 to 0.393). Explants exhibited macrophagic character by staining diffusely with anti-CD11b and CD14 antibodies.

Our culture system repeatably maintained the structural and functional integrity of equine synovial explants over 4 days.

This study establishes a standardized method for culturing equine synovial explants to the aim of accurately modeling of joint diseases and the effects of articular therapeutics.