Effects of TGF-beta1 and hydrostatic pressure on meniscus cell-seeded scaffolds

The combinatorial effects of TGF-beta1 and hydrostatic pressure (HP) were investigated on meniscus cell-seeded PLLA constructs using a two-phase sequential study. The objective was to identify potentially synergistic effects of these stimuli toward enhancing the biomechanical and compositional characteristics of the engineered constructs. In Phase I, the effects of TGF-beta1 were examined on the ability of meniscus cells to produce ECM. In Phase II, meniscus cell-seeded PLLA constructs were cultured for 4 wks with a combination of TGF-beta1 and HP (10 MPa, 0 Hz or 10 MPa, 0.1 Hz). TGF-beta1 was found to increase collagen and GAG deposition in the scaffolds 15-fold and 8-fold, respectively, in Phase I. In Phase II, the combination of TGF-beta1 and 10 MPa, 0 Hz HP resulted in 4-fold higher collagen deposition (additive increase), 3-fold higher GAG deposition and enhanced compressive properties (additive and synergistic increases), when compared to the unpressurized no growth factor culture control. Though significant correlations were observed between the compressive properties (moduli and viscosity), and the GAG and collagen content of the constructs, the correlations were stronger with collagen. This study provides robust evidence that growth factors and HP can be used successfully in combination to enhance the functional properties of in vitro engineered knee meniscus constructs.