Effect of Poly(sophorolipid) Functionalization on Human Mesenchymal Stem Cell Osteogenesis and Immunomodulation

Sophorolipids are a class of glycolipids that can be polymerized via ring-opening metathesis polymerization giving rise to bioresorbable biomaterials. The surface chemistry of the resulting poly(sophorolipids) (pLSLs) can be modified using a combination of enzymatic and "click" chemistries to insert bioactive groups that influence cellular behavior. Mesenchymal stem cells (MSCs) are being actively investigated for engineered bone grafts for fracture repair due to their osteogenic potential, and more recently, due to their immunomodulatory capacity. The long-term goal of this work is to utilize functionalized pLSL foams loaded with MSCs as bioresorbable scaffolds for bone fracture healing. Toward this goal, the present study evaluated the effect of various pLSL chemistries on the osteogenic and immunomodulatory behavior of MSCs. pLSLs functionalized with PO₄, NH₂, or COOH small functional groups were fabricated into open porous foams and then cultured with MSCs in the presence of osteogenic medium for 72 h. Protein level assessments demonstrated that the PO₄-functionalized pLSL foams supported the highest degree of MSC osteogenesis as well as the highest levels of immunomodulatory factors pertinent to improve bone fracture healing. Cumulatively, these results suggest that further investigation of the long-term osteogenic commitment of MSCs in PO₄-functionalized pLSL foams is warranted.