Fabrication, vascularization and osteogenic properties of a novel synthetic biomimetic induced membrane for the treatment of large bone defects

Abstract

The induced membrane has been widely used in the treatment of large bone defects but continues to be limited by a relatively lengthy healing process and a requisite two stage surgical procedure. Here we report the development and characterization of a synthetic biomimetic induced membrane (BIM) consisting of an inner highly pre-vascularized cell sheet and an outer osteogenic layer using cell sheet engineering. The pre-vascularized inner layer was formed by seeding human umbilical vein endothelial cells (HUVECs) on a cell sheet comprised of a layer of undifferentiated human bone marrow-derived mesenchymal stem cells (hMSCs). The outer osteogenic layer was formed by inducing osteogenic differentiation of hMSCs. In vitro results indicated the undifferentiated hMSCs cell sheet facilitated the alignment of HUVECs and significantly promoted the formation of vascular-like networks. Furthermore, seeded HUVECs rearranged the extracellular matrix produced by hMSCs sheet. After subcutaneously implantation, the composite constructs showed rapid vascularization and anastomosis with the host vascular system, forming functional blood vessels in vivo. Osteogenic potential of the BIM was evidenced by immunohistochemistry staining of osteocalcin, tartrate-resistant acid phosphatase (TRAP) staining, and alizarin red staining. In summary, the synthetic BIM showed rapid vascularization, significant anastomoses, and osteogenic potential in vivo. This synthetic BIM has the potential for treatment of large bone defects in the absence of infection.

Simulation of ECM with silk and chitosan nanocomposite materials

“…After 28 days of implantation, the number of newly formed vessels per mm 2 increased by 8% in the pure silk scaffolds, and by 28%, 29% and 42% for the S4-C, S6-C and S8-C scaffolds, respectively. Previous work demonstrated the higher vascularization capacity of the nanofibrous scaffolds, 53 thus the present results implied further improvement by using the ECM simulation strategy.…”

“…49,52 The load was applied until the cylinder was compressed by more than 30% of its original length. 53 The compressive modulus was calculated as the slope of the linear elastic region of the stress-strain curve. Five samples were tested for each group.…”

Silk Biomaterials with Vascularization Capacity

“…Through tuning these two factors, water-insoluble silk scaffolds with reduced crystal structure were prepared directly without further post-treatment. Unlike the scaffolds reported previously, [29–31,35] these new water-insoluble nanofibrous scaffolds were mainly composed of random/silk I structure, providing softer mechanical property and vascularization capacity. The goal of the present study was to exploit this process to generate growth factor-free silk scaffold systems for vascularization needs.…”

Biomaterial-mediated strategies targeting vascularization for bone repair

“…Scaffolds with endothelial cells only displayed immature vascular networks which ultimately regressed while scaffolds only having MSCs had lower blood vessels overall. In a study focusing on a scaffold-free, cell-sheet technology, Ren et al engineered a material having two concentric layers of unique cell sheets encompassing the implant [98]. The inner cell sheet consisted of either mono-cultured MSCs or co-cultured MSCs with HUVECs while the outer sheer contained osteogenically-differentiated MSCs.…”