Elastin‐like‐polypeptide based fusion proteins for osteogenic factor delivery in bone healing

Abstract

Modern treatments of bone injuries and diseases are becoming increasingly dependent on the usage of growth factors to stimulate bone growth. Bone morphogenetic protein-2 (BMP-2), a potent osteogenic inductive protein, exhibits promising results in treatment models, but recently has had its practical efficacy questioned due to the lack of local retention, ectopic bone formation, and potentially lethal inflammation. Where a new delivery technique of the BMP-2 is necessary, here we demonstrate the viability of an elastin-like peptide (ELP) fusion protein containing BMP-2 for delivery of the BMP-2. This fusion protein retains the performance characteristics of both the BMP-2 and ELP. The fusion protein was found to induce osteogenic differentiation of mesenchymal stem cells as evidenced by the production of alkaline phosphatase and extracellular calcium deposits in response to treatment by the fusion protein. Retention of the ELPs inverse phase transition property has allowed for expression of the fusion protein within a bacterial host (such as Escherichia coli) and easy and rapid purification using inverse transition cycling. The fusion protein formed self-aggregating nanoparticles at human-body temperature. The data collected suggests the viability of these fusion protein nanoparticles as a dosage-efficient and location-precise noncytotoxic delivery vehicle for BMP-2 in bone treatment. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1029-1037, 2016.

Recombinant elastin-based nanoparticles for targeted gene therapy

“…The binding of the LDLR3-ELP to the lentiviral vector indicates that the binding ability of LDLR3, in the fusion protein LDLR3-ELP, remained unaffected. This observation is similar to previous studies by several others and us for chimeric ELP fusion proteins where the biological activity of the functional domain remains unaffected by the ELP fusion ( 31 , 32 ). Moreover, the inhibitory activity of LDLR3-ELP without KGF-ELP also demonstrates that its potential application as an agent in antiviral therapy.…”

“…We demonstrated that the fusion protein, LDLR3-ELP, maintained the phase transition property and self-assembled into nanoparticles above transition temperature. These fusion proteins retained the biological activity and phase transitioning properties of ELPs, as shown in previous studies ( 29 , 31 , 32 ). This allowed recombinant expression and simple purification of the fusion proteins by a series of hot and cold cycles.…”

“…This property enables ELPs to be expressed in a bacterial host (such as Escherichia coli ) and to be purified rapidly using inverse temperature cycling (ITC) ( 30 ). Moreover, since ELPs are genetically encodable, chimeric fusion proteins comprising of biologically active motifs and ELPs can be synthesized easily ( 31 , 32 ). These fusion proteins retain the biological activity of the fused motif as well as the phase transitioning property of ELPs, thereby enabling the self-assembly of nanostructures such as nanoparticles above the transition temperature ( 32 ).…”

Genetically Engineered Elastin-based Biomaterials for Biomedical Applications

“…When compared with the control, BMP-V40C2 showed higher alkaline phosphatase activity, higher mRNA levels of osteoblast-specific transcription factor Osterix (OSX) and higher calcium deposition after a 21-day treatment. As such, this study demonstrated that the fusion protein not altered the osteogenic ability of BMP-2 and that the construct retained the transition ability of ELRs [114].…”

“…Some research has been devoted to designing ELRs capable of forming nanoparticles that present growth factors on their surfaces and that can interact with cells. These include growth factors for chronic skin wound treatment [50], for the induction of bone regeneration [51] or the treatment of neuronal injuries [52]. Stromal cell-derived growth factor-1 (SDF1) is a small cytokine belonging to the chemokine family that promotes neovascularization and has been proven to provoke a faster re-epithelialization of skin wounds.…”