Researchers at Northeastern University recently discovered that magnesium oxide (MgO) nanoparticles exhibit some valuable properties for orthopedic tissue engineering when dispersed within polymer composites. Findings show for the first time that MgO nanoparticles significantly increase fibroblast and osteoblast cell attachment and growth on poly(l-lactic acid) (PLLA).
The project, headed by grad student Dan Hickey of Prof. Thomas Webster’s Nanomedicine Lab at Northeastern, is aimed at developing a polymer scaffold to direct the regeneration of the tendon-to-bone insertion site (TBI) following joint reconstruction surgery. The TBI, also called the enthesis, connects ligaments to bone through a complex transitional region that is graded across a fibrocartilaginous zone to disperse large stress concentrations that naturally arise at the junction of soft and hard tissues. However, due to avascularity in the region, the TBI is incapable of fully healing following injury.
To combat the large degree of reported joint instability and graft failure following surgery, the team of researchers at NEU is developing a biodegradable ring shaped scaffold to mimic the structure and function of the natural enthesis. While work is still being done to test and optimize materials for this application, polymers mineralized with nanoparticles of MgO have shown great promise.
Nano-MgO/PLLA composites showed significantly increased adhesion and proliferation of fibroblasts and osteoblasts when compared to plain PLLA and PLLA mineralized with nanoparticles of hydroxyapatite (HA), a major constituent of bone which has been used extensively as a material for bone grafts. Moreover, the addition of nano-MgO allowed for the tailorability of the mechanical properties of PLLA to align with ligament or bone tissue.
Encouraged by these findings, the team recommends future work on using compositional gradients within the scaffold to direct the differentiation of mesenchymal stem cells into ligament, cartilage, and bone tissue based on regionally changing stimuli such as chemistry and scaffold stiffness.