Smart biomaterials: Surfaces functionalized with proteolytically stable osteoblast-adhesive peptides

Engineered scaffolds for bone tissue regeneration are designed to promote cell adhesion,growth,proliferation and differentiation.Recently,covalent and selective functionalization of glass and titanium surfaces with an adhesive peptide(HVP)mapped on[351e359]sequence of human Vitronectin allowed to selectively increase osteoblast attachment and adhesion strength in in vitro assays,and to promote osseointegration in in vivo studies.For the first time to our knowledge,in this study we investigated the resistance of adhesion sequences to proteolytic digestion:HVP was completely cleaved after 5 h.In order to overcome the enzymatic degradation of the native peptide under physiological conditions we synthetized three analogues of HVP sequence.A retro-inverted peptide D-2HVP,composed of D amino acids,was completely stable in serum-containing medium.In addition,glass surfaces functionalized with D-2HVP increased human osteoblast adhesion as compared to the native peptide and maintained deposition of calcium.Interestingly,D-2HVP increased expression of IBSP,VTN and SPP1 genes as compared to HVP functionalized surfaces.Total internal reflection fluorescence microscope analysis showed cells with numerous filopodia spread on D-2HVP-functionalized surfaces.Therefore,the D-2HVP sequence is proposed as new osteoblast adhesive peptide with increased bioactivity and high proteolytic resistance.

Covalent functionalization of decellularized tissues accelerates endothelialization

In the field of tissue regeneration,the lack of a stable endothelial lining may affect the hemocompatibility of both synthetic and biological replacements.These drawbacks might be prevented by specific biomaterial functionalization to induce selective endothelial cell(EC)adhesion.Decellularized bovine pericardia and porcine aortas were selectively functionalized with a REDV tetrapeptide at 10^(-5)M and 10^(-6)M working concentrations.The scaffold-bound peptide was quantified and REDV potential EC adhesion enhancement was evaluated in vitro by static seeding of human umbilical vein ECs.The viable cells and MTS production were statistically higher in functionalized tissues than in control.Scaffold histoarchitecture,geometrical features,and mechanical properties were unaffected by peptide anchoring.The selective immobilization of REDV was effective in accelerating ECs adhesion while promoting proliferation in functionalized decellularized tissues intended for blood-contacting applications.