In these studies, PLGA is combined with another polymer, such as poly(L-lactide) (PLLA), or a bone inductant, such as HA, to induce osteogenesis. Similarly, there are in vivo studies using the same components that demonstrate in vivo osteogenesis. Many of these studies use nanocomposites containing combinations of PLGA, hydroxyapatite (HA), or bone morphogenetic protein 2 (BMP2) and graphene nanoparticles to induce in vitro osteogenesis, or they fabricate scaffolds using complex material chemistries to promote osteogenesis. The combinations of PLGA with commercially available graphene oxide (GO) and reduced graphene oxide (rGO) nanoparticles have been used successfully to demonstrate the enhanced proliferation and osteogenesis of immortalized MC3T3-E1 mouse bone cells and MSCs.
The microCT results were supported by Von Kossa staining. The percentage of bone volume to total volume from microCT analyses in the rats treated with the PLGA + cells construct showed a 50% new tissue formation, which matched that of a phantom. The constructs containing PLGA (50:75)/graphene alone and with hADMSCs demonstrated a significant increase in mineralized tissues within 60 days post-treatment. The results showed that all of the constructs were biocompatible and did not exhibit any adverse effects. Bone repair was monitored by radiological, histological, and microcomputed tomography methods. The in vivo biocompatibility and the potential to repair bones were evaluated in a critically sized 5 mm mechanical load-bearing segmental femur defect model in rats. The cytocompatibility of human ADMSCs transduced with a red fluorescent protein (RFP) was evaluated in vitro. Scanning electron microscopy showed interconnected pores in the lattice structures of each scaffold. Each of these forms of PLGA was blended with a form containing a 50:50 ratio of LA:GA, resulting in ratios of 50:65 and 50:75, which were subsequently mixed with a 0.05 wt% low-oxygen-functionalized derivative of graphene.
The biomaterial inks consisted of two forms of commercially available PLGA with varying ratios of LA:GA (65:35 and 75:25) and molecular weights of 30,000–107,000. Based on the published literature and data from our laboratory, two biomaterial inks containing PLGA and blended with graphene nanoparticles were fabricated. Tissue-engineering technologies have the potential to provide an effective approach to bone regeneration.
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