Transgenic silkworm expressing bioactive human ciliary neurotrophic factor for biomedical application.

Ciliary neurotrophic factor (CNTF) acts as a potent neuroprotective agent in neuronal survival and regeneration, and can also induce the differentiation of several stem cells into neurons, which highlights the broad application of CNTF in biomedicine. However, large-scale production of bioactive recombinant human CNTF protein remains to be explored. Herein, this study aims to express a bioactive human CNTF protein on a large scale by genetically engineering a silk gland bioreactor of silkworm. Our results showed that CNTF protein was successfully expressed in the middle silk gland (MSG) of silkworm, which can be secreted into the silks with the amount of 3.2 mg/g cocoons. The fabrication of human CNTF-functionalized silk material was able to promote proliferation and migration of neural cells when compared to the natural silk protein. Importantly, this functional silk material could also facilitate neurite outgrowth of mouse retinal ganglion cell (RGC-5) cells. All these data demonstrated a high bioactivity of the recombinant human CNTF protein expressed in the MSG of silkworm. The further fabrication of different silk materials with CNTF bioactivity will give biomedical applications in tissue engineering and neuroregeneration.