Effect of endothelial cells on bone regeneration using poly(L‐lactide‐co‐1,5‐dioxepan‐2‐one) scaffolds

Abstract

Our recent in vitro study demonstrated that endothelial cells (ECs) might influence the differentiation of bone marrow stromal cells (BMSCs). Therefore, the aim of this study was to describe this effect in vivo, using a rat calvarial bone defect model. BMSCs were isolated from femurs of two-donor Lewis rats and expanded in α-minimum essential medium containing 10% fetal bovine serum. One fifth of BMSCs were induced and differentiated into ECs in an Endothelial Cell Growth Medium-2 and then characterized by a flow cytometry. The remaining BMSCs were cultured in freshly prepared osteogenic stimulatory medium, containing dexamethasone, ascorbic acid and β-glycerophosphate. Either BMSCs alone (BMSC-group) or co-cultured ECs/BMSCs (CO-group) were seeded into poly(L-lactide-co-1,5-dioxepan-2-one) [poly(LLA-co-DXO)] scaffolds, cultured in spinner flasks, and then implanted into symmetrical calvarial defects prepared in recipient rats. The animals were sacrificed after 2 months. The formation of new bone was evaluated by radiography and histology and by the expression of osteogenic markers using reverse transcriptase-polymerized chain reaction (RT-PCR). To investigate vessel formation, histological staining was performed with EC's markers. The radiographical and histological results showed more rapid bone formation in the CO- than in the BMSC-group. However, the expression of EC's marker was similar on both groups by histological analysis after 2 months postoperatively. Furthermore, the CO-group exhibited greater expression of osteogenic markers as demonstrated by RT-PCR. The results are consistent with the previous in vitro findings that poly(LLA-co-DXO) scaffold might be suitable candidate for bone tissue engineering. In vivo, bone regeneration was enhanced by a construct of the polymer scaffold loaded with co-cultured cells.

In vitro and in vivo degradation profile of aliphatic polyesters subjected to electron beam sterilization

“…Moreover, the scaffolds stimulate osteogenic differentiation of rat and human bone marrow stromal cells and human osteoblastlike cells [7,8,10]. A recent animal study, using a rat calvarial defect model, showed that implantation of scaffolds seeded with endothelial cells and MSC promoted rapid bone formation [11].…”

Co-Culture of Human Bone Marrow Stromal Cells with Endothelial Cells Alters Gene Expression Profiles

“…Previous studies have shown that co-culture with endothelial cells enhances cellular proliferation of MSCs and induces differentiation into osteogenic cells with up-regulation of alkaline phosphatase (ALP) expression (5, 6). It has also been reported that EC co-cultured with OB are able to establish microcapillary-like structures in a 3D scaffold (4). Both the MSC and EC network express connexion 43 (C × 43), a specific gap junction protein, suggesting that the two cell types communicate via a gap junction channel comprising C × 43 (5).…”

“…Another important role of vascularization in bone formation is the delivery of growth factors, which controls the recruitment, proliferation, differentiation, function, and/or survival of the bone cells. Angiogenesis precedes osteogenesis, and is an absolute requirement for osteogenesis to occur (4). …”

“…Applying co-cultured OB and EC within RGD-grafted alginate microspheres implanted in a long bone defect in mice showed significantly enhanced mineralization of the microspheres (2). Furthermore, bone regeneration in a rat calvarial defect was enhanced by a tissue-engineered construct of a polymer scaffold, loaded with co-cultured cells (4). The studies (4) suggest that EC can influence not only osteogenic differentiation in vitro, but also osteogenesis in vivo .…”

Nano-ceramic Composite Scaffolds for Bioreactor-based Bone Engineering

“…With static culture techniques, the transportation of oxygen, nutrients, and low-molecular-weight metabolites is limited by diffusion preventing cells from being able to survive in the scaffold interior. To overcome this problem, a variety of dynamic culture systems have been used including perfusion bioreactors [45,56], spinner flasks [32,58], roller bottles [26], and rotating wall bioreactors [55,59]. The high-aspect ratio vessel (HARV) bioreactor is a low-shear, high-mass transfer system that improves cell-seeded bone tissue-engineering scaffold performance [6,9,60].…”