Special Issue "Composite Materials in Skeletal Engineering"

Guest Editor
Prof. Dr. Mohamed N. Rahaman
Department of Materials Science and Engineering, Center for Bone and Tissue Repair and Regeneration, Missouri University of Science and Technology, 223 McNutt Hall, 1400 N. Bishop Avenue, Rolla, Missouri 65409-0340, USA
Website: http://www.mst.edu/~rahaman/
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Guest Editor
Dr. B. Sonny Bal
Department of Orthopaedic Surgery, University of Missouri School of Medicine, Columbia, MO 65201, USA
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Dear Colleagues,

Skeletal tissues, such as bone, muscles, tendon, and ligaments represent a remarkable feat of nature’s engineering. These tissues are designed for a lifetime of repetitive, complex loading, with the capacity for healing and repair. Reproducing skeletal tissues with synthetic materials is an engineering challenge.

Composite materials provide a wider range of properties than the basic classes of materials (metals, ceramics, and polymers), so they offer an attractive approach for mimicking the properties of skeletal tissues. Interest in nanocomposites stems from the significant property advantages which they can offer over their conventional counterparts. The recently-developed field of tissue-engineering is attracting considerable interest for the regeneration of diseased or damaged tissues; it is probable that composite materials will play a significant role in repairing or restoring human skeletal tissue.

In this issue, recent advances in the development of composite materials for the repair and regeneration of skeletal tissues are emphasized and discussed. Guest authors describe advances in the fabrication, design, and testing of these materials. It is hoped that this special issue will serve as a platform for the cross-fertilization of ideas and concepts that ultimately lead to products and developments to advance improved skeletal health for humans.

Mohamed N. Rahaman, Ph.D.
B. Sonny Bal, Ph.D.
Guest Editors

Submission

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• processing and fabrication
• structural, mechanical, and biological properties
• engineered composite tissues
• applications

Title: Enhancing Osteoconduction of Plla-Based Nanocomposite Scaffolds For Bone Regeneration Using Different Biomimetic Signals To MSC
Author: Gabriela Ciapetti
Affiliation: E-Mail: gabriela.ciapetti@ior.it
Abstract: In bone engineering the adhesion, proliferation and differentiation of mesenchymal stromal cells rely on signaling from chemico-physical structure of the substrate, therefore prompting the design of mimetic ECM-like scaffolds. In this study three-dimensional porous poly-L-lactic acid-based scaffolds have been mixed with different components, including single walled carbon nanotubes (SWCNT), micro-hydroxyapatite particles (µHA), and BMP2, and treated with plasma (PT), and four different nanocomposites: PLLA-SWCNT, PLLA-SWCNTµHA, PLLA-SWCNT-µHA-BMP2 and PLLA-SWCNT-µHA-PT were obtained. Adult bone marrow mesenchymal cells (MSC) were collected from the femur of orthopaedic patients, seeded on the scaffolds and cultured under osteogenic induction up to cell differentiation and mineralization. The release of specific metabolites and temporal gene expression profiles of marrow-derived osteoprogenitors were analysed at definite time points, relevant to in vitro culture as well as in vivo differentiation. As a result, the role of the different biomimetic components added to the PLLA matrix was described, with BMP2-added scaffolds showing the highest biomimetic activity on cells differentiating to mature osteoblasts. The addition of a polymeric scaffold with reinforcing components which also work as biomimetic cues for cells can effectively direct osteoprogenitor cells to a mature phenotype, so as to shorten the time required for bone deposition.

Title: Early Fixation of Cobalt-Chromium Surgical Implants to Bone Using Tissue-Engineering Approach
Authors: Hajime Ohgushi; M. Ogawa and Y. Thoma
Affiliation: E-Mail: hajime-ohgushi@aist.go.jp
Abstract: To establish the methods to show early fixation of metal implants to bone, rabbit mesenchymal stem cells (MSCs) were seeded on one side the Cobalt-Chromium test implant surface, whereas the MSCs were not seeded on other side. The MSCs were further cultured in osteogenic condition resulted in the appearance of osteoblasts and bone matrix on the implant surface. Thus, we succeeded to generate tissue-engineered bone on one side of the implant. The implants were placed in rabbit bone defects. Three weeks after the implantation, evaluations of mechanical bonding, undecalcified histological section and electron microscope analysis were performed. Histological and electron microscope images of the tissue engineered surface exhibited abundant new bone formation. However, the new bone was hard to be detected on other side without cell seeding. In the mechanical test, the average failure loads were 0.70 kgf and 0.42 kgf for the tissue-engineered and non-cell-seeded surfaces, respectively. These findings indicate early bone fixation of the tissue-engineered Cobalt-Chromium surface even three weeks after implantation.