Zhiqing Chen

Ectopic Bone Formation in Adipose-derived Stromal Cell-seeded Osteoinductive Calcium Phosphate Scaffolds

The phenomenon of osteoinduction by biomaterials has been proven and used in animals. However, whether the ability of a biomaterial to initiate bone formation in ectopic implantation sites improves the performance of such osteoinductive biomaterial as a scaffold for tissue-engineered (TE) bone remains unclear. In this study, we compared ectopic bone formation by combining autologous adipose-derived stromal cells (ADSCs) with an osteoinductive and a nonosteoinductive biphasic calcium phosphate (BCP) ceramic to create a tissue engineering construct in the muscle of dogs. Two groups of BCP scaffolds (BCP1 and BCP2) were prepared. In each group, ADSCs were seeded, and the scaffolds without seeded cells served as controls. All implants were implanted in the back muscle of 10 adult dogs for 8 weeks and 12 weeks. Microcomputed tomography (Micro-CT) analysis and histomorphometry were performed to evaluate and quantify ectopic bone formation. The results indicated that the osteoinductive BCP1 performed significantly better compared to the nonosteoinductive BCP2 in cell-based TE bone formation ectopically. The ADSCs had a significantly positive effect on the ectopic bone formation. In addition, the usefulness of Micro-CT for the efficient and nondestructive analysis of mineralized bone and calcium phosphate scaffold was confirmed.

Preliminary Evaluation of a Novel Strong/Osteoinductive Calcium Phosphate Cement

We developed a novel calcium phosphate cement (CPC) by combining the silk fibroin and osteogenic supplements (β-glycerophosphate, ascorbic acid, and dexamethasone) with α-tricalcium phosphate cement. Mesenchymal stem cells (MSCs) were cultured on the novel CPC scaffold. Results showed that the novel CPC scaffold was biocompatible and favorable for the adhesion, spreading, and proliferation of MSCs. Osteogenic differentiation of MSCs was confirmed by high osteocalcin content and elevated gene expressions of bone markers, such as alkaline phosphatase, collagen type I, and osteocalcin. Therefore, the novel CPC scaffold may be potentially useful for implant fixation and more rapid new bone formation in moderate load-bearing applications.

Manufacture and cytotoxicity of a lead-free piezoelectric ceramic as a bone substitute-consolidation of porous lithium sodium potassium niobate by cold isostatic pressing.

AimThe piezoelectric properties and cytotoxicity of a porous lead‐free piezoelectric ceramic for use as a direct bone substitute were investigated.MethodologyCold isostatic pressing (CIP) was applied to fabricate porous lithium sodium potassium niobate (Li0.06Na0.5K0.44) NbO3 specimens using a pore‐forming method. The morphologies of the CIP‐processed specimens were characterized and compared to those of specimens made by from conventional pressing procedures. The effects of the ceramic on the attachment and proliferation of osteoblasts isolated from the cranium of 1‐day‐old Sprague‐Dawley rats were examined by a scanning electron microscopy (SEM) and methylthiazol tetrazolium (MTT) assay.ResultsThe results showed that CIP enhanced piezoelectricity and biological performance of the niobate specimen, and also promoted an extracellular matrix‐like topography of it. In vitro studies showed that the CIP‐enhanced material had positive effects on the attachment and proliferation of osteoblasts.ConclusionNiobate ceramic generated by CIP shows a promise for being a piezoelectric composite bone substitute.

A novel technique to reconstruct a boxlike bone defect in the mandible and support dental implants with In vivo tissue-engineered bone.

The purpose of this study was to investigate the feasibility of using in vivo tissue-engineered (TE) bone to repair boxlike mandibular defect and support dental implant, and then provide experimental evidence for the future application of the novel technique in the clinical setting. The TE bone graft was constructed in vivo by implanting osteoinductive calcium phosphate (Ca-P) ceramics in the femoral muscles of dog for 8 weeks, then was transplanted to repair the autogeneic boxlike bone defect site created in one side of the mandible and simultaneously support a dental implant, while in the opposite side of the mandibular defect, the same ceramic was used directly as control. 8 weeks after transplantation, samples were harvested for analysis. The results demonstrated that the technique of in vivo tissue engineering improved the mechanical and biologic properties of ceramics significantly. After transplantation, the in vivo TE ceramic-bone grafts were involved in bone metabolism of the host and fused well with the host bone. The dental implants were stable and had been integrated with both TE bone grafts and autologous bone. Therefore, it is feasible to construct a live bone graft with osteoinductive Ca-P ceramics in vivo, then repair a mandibular bone defect, and support a dental implant. In conclusion, in vivo TE bone is a promising technique for bone repair.