Small Animal Surgery Resident Oregon State University Corvallis, Oregon
Meniscal tissue engineering serves as a potential alternative to current treatments for canine meniscal injury. To date, replacement meniscal tissue has not been successfully tissue engineered, in part due to lack of in vitro culture with compressive and shear biomechanical stimulation, appropriate to the stage of tissue formation. The goal of this study was to guide cell differentiation and increase ECM formation by exercising cell-seeded hydrogels in a simple knee-like bioreactor. Hydrogels were formed into meniscus-like shapes and a stainless-steel ball was used to mimic the contact interface between the convex surface of femoral condyle and hydrogel. This “condylar” steel ball provides static compression on the cells within the hydrogel, and was also used to generate dynamic compression and shear forces when rocked with an orbital shaker. Seeded hydrogels were “exercised” on the shaker for either 1 or 4 hours per day, for a total of 4 weeks culture time. Hydrogels were then harvested and analyzed histologically and spectrophotometrically for cellularity and meniscal-like glycosaminoglycan and collagen ECM distribution and content. Hydrogels receiving 4 hours of exercise per day had increased chondrogenic cellular activity. A dense zone of collagenous neotissue formed on the superior surface of the hydrogel, particularly in the abaxial zone. This group also had greater glycosaminoglycan washout in the culture media as compared to the short exercise group. The limitations of the study included small sample size and treatment groups. However, the tissue cultured with the designed scaffold and force application is promising for future meniscal tissue engineering.
