Transgenic expression and functional characterization of human platelet derived growth factor BB (hPDGF-BB) in tobacco (Nicotiana tabacum L.)

In Vitro Angiogenic Properties of Plasmid DNA Encoding SDF-1α and VEGF165 Genes

The stromal-derived factor-1 alpha (SDF-1α) and vascular endothelial growth factor (VEGF) play an important role in angiogenesis and exert a significant trophic function. SDF-1α is a chemoattractant for endothelial progenitor cells derived from bone marrow and promotes new blood vessel formation. VEGF regulates all types of vascular growth, stimulates angiogenesis, and is involved in the induction of lymphangiogenesis. The possibility of using these growth factors for regenerative medicine is currently under investigation. The angiogenic potential of a pBud-SDF-1α-VEGF165 bicistronic plasmid construct which simultaneously encodes VEGF165 and SDF-1α genes cDNA was evaluated in this study. The conditioned medium collected from HEK293T cells transfected with the pBud-SDF-1α-VEGF165 plasmid was shown to stimulate the formation of capillary-like structures by human umbilical vein-derived endothelial cells (HUVEC) on Matrigel and to increase the proliferative activity of these cells in vitro. Thus, the pBud-SDF-1α-VEGF165 plasmid exhibits angiogenic properties in cell cultures in vitro. As interest in the development of non-viral techniques for regenerative medicine increases, this plasmid which simultaneously expresses VEGF165 and SDF-1α may provide a platform for advanced methods of stimulating therapeutic angiogenesis.

Transgenic Silkworm-Based Silk Gland Bioreactor for Large Scale Production of Bioactive Human Platelet-Derived Growth Factor (PDGF-BB) in Silk Cocoons

Human platelet derived growth factor (PDGF) is a major therapeutic protein with great demand in the clinical setting; however, its rate of supply is far from meeting needs. Here, we provide an effective strategy to produce PDGF-BB in large quantities using a transgenic silkworm. The codon-optimized PDGF-B gene regulated by the highly efficient sericin-1 expression system was integrated into the genome of a silkworm. The high transcriptional expression of the PDGF-BB gene in the transgenic silkworm competitively inhibited the transcription expression of the endogenous sericin-1 gene which caused a significant 37.5% decline. The PDGF-BB synthesized in the middle silk gland (MSG) of transgenic silkworms could form a homodimer through intermolecular disulfide bonds, which is then secreted into sericin lumen and finally, distributed in the sericin layer of the cocoon. In this study, a protein quantity of approximately 0.33 mg/g was found in the cocoon. Following a purification process, approximately 150.7 μg of recombinant PDGF-BB with a purity of 82% was purified from 1 g of cocoons. Furthermore, the bioactivity assays showed that the purified recombinant PDGF-BB was able to promote the growth, proliferation and migration of NIH/3T3 cells significantly. These results suggest that the silk gland bioreactor can produce active recombinant PDGF-BB as an efficient mitogen and wound healing agent.