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.

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