Fibronectin is well-known as an attachment extracellular matrix (ECM) protein that promotes activity, including differentiation, of a number of cell types. It has also been used in a number of tissue engineered constructs to enhance their function as well as cellular proliferation. As a workhorse ECM protein, fibronectin’s use is well-established in many tissue engineering and cell culture applications. Many questions, however, remain on the relationship between fibronectin and tissue constructs, other proteins and various delivery environments.
We report here on a new study that investigated the effect of human plasma fibronectin and BMP (bone morphogenic factor) to enhance the osteogenic activity of these biologics when delivered in different ways. BMPs stimulate bone growth in the human body, and are heavily used in applications geared toward bone reconstruction.
The study, published in Acta Biometerialia, compared the in vitro osteogenic efficacy of three BMP variants: BMP-2, BMP-6 and BMP-7, delivered alongside fibronectin. The authors used two different delivery strategies: BMP/fibronectin mixtures were delivered to mouse C2C12 pre-osteoblasts either in solution or coated onto titanium-hydroxyapatite (TiHA) surfaces as models of tissue-engineered implants.
The study found that the affinity of different BMPs for FN was dependent on BMP type. For instance, fibronectin with BMP-6 delivered on TiHA surfaces increased gene-mediated osteogenic activity. Combining fibronectin with BMP-7 did not yield measurable function. The osteogenic activity was also significantly increased for BMP-6/fibronectin coatings when delivered in vivo. This was corroborated by surface plasmon resonance-driven molecular binding studies.
The study shed some more light, based on affinity and activity experiments, on the effect of fibronectin on optimal conditions for bone regeneration when delivered alongside BMP.
It also alludes to the fact that developing optimal bioengineered implants for bone regeneration – though other applications as well – is highly reliant on the understand on the molecualr interactions between fibronectin and other components of the in vivo implant environment.