Mechanical and Functional Improvement of β-TCP Scaffolds for Use in Bone Tissue Engineering

Bone-Mimetic Osteon Microtopographies on Poly-ε-Caprolactone Enhance the Osteogenic Potential of Human Mesenchymal Stem Cells

The attributes of implant surfaces are pivotal for successful osseointegration. Among surface engineering strategies, microtopography stands out as a promising approach to promote early cellular interactions. This study aims to design and craft a novel biomimetic osteon-like surface modification and to compare its impact on human mesenchymal stem cells (hMSCs) with four established topographies: blank, inverted pyramids, protrusions, and grooves. Poly-ε-caprolactone samples are fabricated using 2-photon-polymerization and soft lithography, prior to analysis via scanning electron microscopy (SEM), water contact angle (WCA), and protein adsorption assays. Additionally, cellular responses including cell attachment, proliferation, morphology, cytoskeletal organization, and osteogenic differentiation potential are evaluated. SEM confirms the successful fabrication of microtopographies, with minimal effect on WCA and protein adsorption. Cell attachment experiments demonstrate a significant increase on the osteon-like structure, being three times higher than on the blank. Proliferation assays indicate a fourfold increase with osteon-like microtopography compared to the blank, while ALP activity is notably elevated with osteon-like microtopography at days 7 (threefold increase over blank) and 14 (fivefold increase over blank). In conclusion, the novel biomimetic osteon-like structure demonstrates favorable responses from hMSCs, suggesting potential for promoting successful implant integration in vivo.

Absorbable calcium and phosphorus bioactive membranes promote bone marrow mesenchymal stem cells osteogenic differentiation for bone regeneration

Large segmental bone defects are commonly operated with autologous bone grafting, which has limited bone sources and poses additional surgical risks. In this study, we fabricated poly(lactide-co-glycolic acid) (PLGA)/β-tricalcium phosphate (β-TCP) composite membranes by electrostatic spinning and further promoted osteogenesis by regulating the release of β-TCP in the hope of replacing autologous bone grafts in the clinical practice. The addition of β-TCP improved the mechanical strength of PLGA by 2.55 times. Moreover, β-TCP could accelerate the degradation of PLGA and neutralize the negative effects of acidification of the microenvironment caused by PLGA degradation. In vitro experiments revealed that PLGA/TCP10 membranes are biocompatible and the released β-TCP can modulate the activity of osteoblasts by enhancing the calcium ions concentration in the damaged area and regulating the pH of the local microenvironment. Simultaneously, an increase in β-TCP can moderate the lactate content of the local microenvironment, synergistically enhancing osteogenesis by promoting the tube-forming effect of human umbilical vein endothelial cells. Therefore, it is potential to utilize PLGA/TCP bioactive membranes to modulate the microenvironment at the site of bone defects to promote bone regeneration.

Three-Dimensionally Cultured Jaw Periosteal Cells Attenuate Macrophage Activation of CD4+ T Cells and Inhibit Osteoclastogenesis

The implementation of a successful therapeutic approach that includes tissue-engineered grafts requires detailed analyses of graft-immune cell interactions in order to predict possible immune reactions after implantation. The phenotypic plasticity of macrophages plays a central role in immune cell chemotaxis, inflammatory regulation and bone regeneration. The present study addresses effects emanating from JPC-seeded β-TCP constructs (3DJPCs) co-cultivated with THP-1 derived M1/M2 macrophages within a horizontal co-culture system. After five days of co-culture, macrophage phenotype and chemokine secretion were analyzed by flow cytometry, quantitative PCR and proteome arrays. The results showed that pro-inflammatory factors in M1 macrophages were inhibited by 3DJPCs, while anti-inflammatory factors were activated, possibly affected by the multiple chemokines secreted by 3D-cultured JPCs. In addition, osteoclast markers of polarized macrophages were inhibited by osteogenically induced 3DJPCs. Functional assays revealed a significantly lower percentage of proliferating CD4+ T cells in the groups treated with secretomes from M1/M2 macrophages previously co-cultured with 3DJPCs compared to controls without secretomes. Quantifications of pit area resorption assays showed evidence that supernatants from 3DJPCs co-cultured with M1/M2 macrophages were able to completely suppress osteoclast maturation, compared to the control group without secretomes. These findings demonstrate the ability of 3D cultured JPCs to modulate macrophage plasticity.