Microencapsulation of mechano growth factor E peptide for sustained delivery and bioactivity maintenance

Mechano growth factor (MGF) and its C-terminal E-peptide with 24 amino acids, MGF-Ct24E, have superiority in resolving the delayed or failed bone repair derived from shortness of suitable biomechanical stimulation. The chitosan/tripolyphosphate microspheres encapsulated with MGF-Ct24E (CS/TPP/MGF-Ct24E) are prepared using emulsion-ionic cross-linking method in order to achieve the sustained release and preserve the bioactivity of MGF-Ct24E. The microspheres are micron-sized and spherical in shape with smooth surface morphology. The TPP component disintegrates in advance of CS matrix and the MGF-Ct24E maintains sustained delivery during in vitro hydrolytic degradation. With the disappearance of TPP, the total weight loss of CS/TPP/MGF-Ct24E is 32% and the release amount of MGF-Ct24E reaches 84.6% after degrading for 2 weeks. In vitro bioactivity assays reveal that the MGF-Ct24E can accelerate MC3T3-E1 cells proliferation and delay their differentiation as well. The encapsulated MGF-Ct24E shows long-term effects after being loaded in the CS/TPP microspheres and the cells exhibit excellent morphology on the surface of microspheres. The continuous delivery of MGF-Ct24E provides a new perspective on resolving the unsatisfactory bone reconstruction associated with microgravity and stress shielding.