Expansion of mesenchymal stem cells on fibrinogen-rich protein surfaces derived from blood plasma

Abstract

Mesenchymal stem cells (MSCs) are present in low density in bone marrow and culture expansion is necessary to obtain sufficient numbers for many proposed therapies. Researchers have characterized MSC growth on tissue culture plastic (TCP), although few studies have explored proliferation on other growth substrates. Using adult equine MSCs, we evaluated proliferation on fibrinogen-rich precipitate (FRP) surfaces created from blood plasma. When seeded at 1 × 10(4) cells/cm(2) and passaged five times over 10 days, MSCs on FRP in medium containing fibroblast growth factor 2 (FGF2) resulted in a ∼2.5-fold increase in cell yield relative to TCP. In FGF2-free medium, FRP stimulated a 10.4-fold increase in cell yield over TCP after 10 days, although control cultures maintained in FGF2 on TCP demonstrated that the stimulatory effect of FRP was not as lasting as that of FGF2. Chondrogenic cultures demonstrated that FRP did not affect differentiation. On TCP, MSCs seeded at 500 cells/cm(2) experienced a 4.6-fold increase in cell yield over cultures seeded at 1 × 10(4) cells/cm(2) following 10 days of expansion. In 500 cells/cm(2) cultures, FRP stimulating a two-fold increase in cell yield over TCP without affecting differentiation. Low-density FRP cultures showed a more even distribution of cells than TCP, suggesting that FRP may accelerate proliferation by reducing contact inhibition that slows proliferation. In addition, FRP appears capable of binding FGF2, as FRP surfaces pre-conditioned with FGF2 supported greater proliferation than FGF2-free cultures. Taken together, these factors indicate that substrates obtained from simple and inexpensive processing of blood enhance MSC proliferation and promote efficient coverage of expansion surfaces.