Abstract
Purpose: :
To characterise the chemical composition and physical properties of the bovine lens capsule with a view to develop artificial 3D matrices tailored to lens cell in vitro culture.
Methods: :
Collagen matrices were assembled from purified bovine tendon collagen I, human placenta collagen IV (SIGMA-ALDRICH) and purified bovine lens capsule collagen IV. Together with a polystyrene 3D matrix (Re:Innervate), the physical structure and suitability of the collagen matrices for lens epithelial cell culture was assessed by scanning electron microscopy. Protein composition of both anterior and posterior bovine lens capsule was determined by mass spectrometry to identify non-collagenous proteins of functional significance to the maintenance of lens epithelial cell phenotype in vitro. Cell survival and protein expression of the lens epithelial cells cultured on the different substrates produced were checked by viability assays and immunoblotting, respectively.
Results: :
Polystyrene, purified collagen I, purified collagen IV and bovine lens capsule collagen IV all assembled into 3D networks compatible with lens epithelial cells culture in vitro. Presence of all three collagen networks also conferred greater lens epithelial cell survival during serum-free culture compared to 2D plastic culture. Also, the chemical composition of the bovine lens capsule indicated that it is not a mere physical support for the lens epithelial cells, but a store for several factors relevant to lens epithelial cells physiology (SPARC, betaB2-crystallin), that can be accessed by the cells via enzyme secretion (MMP-2).
Conclusions: :
The lens capsule is a complex 3D basement membrane rich in survival factors that can be accessed by lens epithelial cells to promote greater survival under stress conditions. The purification and re-assembly of its major components can be successfully used to improve in vitro models of lens epithelial cell culture.
Keywords: extracellular matrix • cell survival • EMT (epithelial mesenchymal transition)