The use of zein and Shuanghuangbu for periodontal tissue engineering

Yan-Zhi X, Jing-Jing W, Chen YP, Liu J, Li N, Yang FY.

Department of Stomatology, the Fourth Hospital of Hebei Medical University, Shijiazhuang, China. xu_yanzhi[at]163.com

Abstract
AIM:
Tissue engineering is a promising area with a broad range of applications in the fields of regenerative medicine and human health. The emergence of periodontal tissue engineering for clinical treatment of periodontal disease has opened a new therapeutic avenue. The choice of scaffold is crucial. This study was conducted to prepare zein scaffold and explore the suitability of zein and Shuanghuangbu for periodontal tissue engineering.
METHODOLOGY:
A zein scaffold was made using the solvent casting/particulate leaching method with sodium chloride (NaCl) particles as the porogen. The physical properties of the zein scaffold were evaluated by observing its shape and determining its pore structure and porosity. Cytotoxicity testing of the scaffold was carried out via in vitro cell culture experiments, including a liquid extraction experiment and the direct contact assay. Also, the Chinese medicine Shuanghuangbu, as a growth factor, was diluted by scaffold extract into different concentrations. This Shuanghuangbu-scaffold extract was then added to periodontal ligament cells (PDLCs) in order to determine its effect on cell proliferation.
RESULTS:
The zein scaffold displayed a sponge-like structure with a high porosity and sufficient thickness. The porosity and pore size of the zein scaffold can be controlled by changing the porogen particles dosage and size. The porosity was up to 64.1%-78.0%. The pores were well-distributed, interconnected, and porous. The toxicity of the zein scaffold was graded as 0-1. Furthermore, PDLCs displayed full stretching and vigorous growth under scanning electronic microscope (SEM). Shuanghuangbu-scaffold extract could reinforce proliferation activity of PDLCs compared to the control group, especially at 100 microg x mL(-1) (P < 0.01).
CONCLUSION:
A zein scaffold with high porosity, open pore wall structure, and good biocompatibility is conducive to the growth of PDLCs. Zein could be used as scaffold to repair periodontal tissue defects. Also, Shuanghuangbu-scaffold extract can enhance the proliferation activity of PDLCs. Altogether, these findings provide the basis for in vivo testing on animals.

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Controlled delivery of inductive proteins, plasmid DNA and cells from tissue engineering matrices.

Murphy WL, Mooney DJ.

Department of Biomedical Engineering, University of Michigan, Ann Arbor 48109-2136, USA.

Abstract

It has been estimated that half the annual health care budget in the United States is spent on patients suffering from tissue loss and late stage organ failure. Critical limitations inherent in traditional therapies call for novel tissue and organ replacement strategies. This paper discusses development of biomaterials for conductive, inductive and cell-based tissue replacement strategies. Biodegradable polymer scaffolds can be used as space-filling matrices for tissue development and barriers to migration of epithelial cells in tissue conductive approaches. Inductive approaches involve sustained delivery of bioactive factors, such as protein growth factors and DNA, to alter cell function in localized regions. Factors can be released from highly porous polymer scaffolds to allow factor delivery and tissue development to occur in concert. Cell-based approaches involve seeding of cells onto polymeric scaffolds in vitro and subsequent transplantation of the scaffold. New scaffold materials are being developed that address specific tissue engineering design requirements, and in some cases attempt to mimic natural extracellular matrices. These strategies together offer the possibility of predictably forming specific tissue structures, and may provide solutions to problems such as periodontal ligament detachment, alveolar bone resorption and furcation defects.

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Control of pore size and structure of tissue engineering scaffolds produced by supercritical fluid processing

Tai H, Mather ML, Howard D, Wang W, White LJ, Crowe JA, Morgan SP, Chandra A, Williams DJ, Howdle SM, Shakesheff KM.

School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK.

Abstract

Tissue engineering scaffolds require a controlled pore size and structure to host tissue formation. Supercritical carbon dioxide (scCO2) processing may be used to form foamed scaffolds in which the escape of CO2 from a plasticized polymer melt generates gas bubbles that shape the developing pores. The process of forming these scaffolds involves a simultaneous change in phase in the CO2 and the polymer, resulting in rapid expansion of a surface area and changes in polymer rheological properties. Hence, the process is difficult to control with respect to the desired final pore size and structure. In this paper, we describe a detailed study of the effect of polymer chemical composition, molecular weight and processing parameters on final scaffold characteristics. The study focuses on poly(DL-lactic acid) (PDLLA) and poly(DL-lactic acid-co-glycolic acid) (PLGA) as polymer classes with potential application as controlled release scaffolds for growth factor delivery. Processing parameters under investigation were temperature (from 5 to 55 degrees C) and pressure (from 60 to 230 bar). A series of amorphous PDLLA and PLGA polymers with various molecular weights (from 13 KD to 96 KD) and/or chemical compositions (the mole percentage of glycolic acid in the polymers was 0, 15, 25, 35 and 50 respectively) were employed. The resulting scaffolds were characterised by optical microscopy, scanning electron microscopy (SEM), and micro X-ray computed tomography (microCT). This is the first detailed study on using these series polymers for scaffold formation by supercritical technique. This study has demonstrated that the pore size and structure of the supercritical PDLLA and PLGA scaffolds can be tailored by careful control of processing conditions.

Key Words: poly(DL-lactic acid) (PDLLA), poly(lactic acid-co-glycolic acid) (PLGA), supercritical carbon dioxide (scCO2), plasticization, foaming, scaffolds

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Direct deposited porous scaffolds of calcium phosphate cement with alginate for drug delivery and bone tissue engineering

Lee GS, Park JH, Shin US, Kim HW.

Department of Nanobiomedical Science and WCU Research Center, Dankook University Graduate School, Cheonan, South Korea.

Abstract

This study reports the preparation of novel porous scaffolds of calcium phosphate cement (CPC) combined with alginate, and their potential usefulness as a three-dimensional (3-D) matrix for drug delivery and tissue engineering of bone. An α-tricalcium phosphate-based powder was mixed with sodium alginate solution and then directly injected into a fibrous structure in a Ca-containing bath. A rapid hardening reaction of the alginate with Ca(2+) helps to shape the composite into a fibrous form with diameters of hundreds of micrometers, and subsequent pressing in a mold allows the formation of 3-D porous scaffolds with different porosity levels. After transformation of the CPC into a calcium-deficient hydroxyapatite phase in simulated biological fluid the scaffold was shown to retain its mechanical stability. During the process biological proteins, such as bovine serum albumin and lysozyme, used as model proteins, were observed to be effectively loaded onto and released from the scaffolds for up to more than a month, proving the efficacy of the scaffolds as a drug delivering matrix. Mesenchymal stem cells (MSCs) were isolated from rat bone marrow and then cultured on the CPC-alginate porous scaffolds to investigate the ability to support proliferation of cells and their subsequent differentiation along the osteogenic lineage. It was shown that MSCs increasingly actively populated and also permeated into the porous network with time of culture. In particular, cells cultured within a scaffold with a relatively high porosity level showed favorable proliferation and osteogenic differentiation. An in vivo pilot study of the CPC-alginate porous scaffolds after implantation into the rat calvarium for 6 weeks revealed the formation of new bone tissue within the scaffold, closing the defect almost completely. Based on these results, the newly developed CPC-alginate porous scaffolds could be potentially useful as a 3-D matrix for drug delivery and tissue engineering of bone.
Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Keywords: Porous scaffolds; Self-setting cements; Calcium phosphates; Protein delivery; Bone regeneration

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In vitro - Osteoclastic Activity Studies on Surfaces of 3D Printed Calcium Phosphate Scaffolds

Rainer Detsch
BioCer Entwicklungs-GmbH, Bayreuth 95447, Germany, rainer.detsch@biocer-gmbh.de
Susannne Schaefer
Friedrich-Baur-Research Institute for Biomaterials, University of Bayreuth Bayreuth 95440, Germany
Ulrike Deisinger
Friedrich-Baur-Research Institute for Biomaterials, University of Bayreuth Bayreuth 95440, Germany
Guenter Ziegler
BioCer Entwicklungs-GmbH, Bayreuth 95447, Germany, Friedrich-Baur-Research Institute for Biomaterials, University of Bayreuth Bayreuth 95440, Germany
Hermann Seitz
Fluid Technology and Microfluidics, University of Rostock Rostock 18059, Germany, Research Center Caesar, Bonn 53175, Germany
Barbara Leukers
Research Center Caesar, Bonn 53175, Germany

Abstract

Various biomaterials have been developed for the use as bone substitutes for bone defects. To optimize their integration and functionality, they should be adapted to the individual defect. Rapid prototyping is a manufacturing method to tailor materials to the 3D geometry of the defect. Especially 3D printing allows the manufacture of implants, the shape of which can be designed to fit the bone defect using anatomical information obtained from the patient. 3D printing of calcium phosphates, which are well established as bone substitutes, involves a sintering step after gluing the granules together by a binder liquid. In this study, we analyzed if and how these 3D printed calcium phosphate surfaces can be resorbed by osteoclast-like cells. On 3D printed scaffold surfaces consisting of pure HA and β-TCP as well as a biphasic mixture of HA and TCP the osteoclastic cell differentiation was studied. In this regard, cell proliferation, differentiation, and activation were analyzed with the monocytic cell line RAW 264.7. The results show that osteoclast-like cells were able to resorb calcium phosphate surfaces consisting of granules. Furthermore, biphasic calcium phosphate ceramics exhibit, because of their osteoclastic activation ability, the most promising surface properties to serve as 3D printed bone substitute scaffolds.

Keywords: bone reconstruction 3D printing calcium phosphate ceramics osteoclast development resorption.

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Scaffold: a novel carrier for cell and drug delivery.

Garg T, Singh O, Arora S, Murthy R.

Department of Pharmaceutics, ISF College of Pharmacy, Moga (Punjab), India 09501223252(M). tarun.garg9 [ at ] gmail.com

Abstract

Scaffolds are implants or injects, which are used to deliver cells, drugs, and genes into the body. Different forms of polymeric scaffolds for cell/drug delivery are available: (1) a typical three-dimensional porous matrix, (2) a nanofibrous matrix, (3) a thermosensitive sol-gel transition hydrogel, and (4) a porous microsphere. A scaffold provides a suitable substrate for cell attachment, cell proliferation, differentiated function, and cell migration. Scaffold matrices can be used to achieve drug delivery with high loading and efficiency to specific sites. Biomaterials used for fabrication of scaffold may be natural polymers such as alginate, proteins, collagens, gelatin, fibrins, and albumin, or synthetic polymers such as polyvinyl alcohol and polyglycolide. Bioceramics such as hydroxyapatites and tricalcium phosphates also are used. Techniques used for fabrication of a scaffold include particulate leaching, freeze-drying, supercritical fluid technology, thermally induced phase separation, rapid prototyping, powder compaction, sol-gel, and melt moulding. These techniques allow the preparation of porous structures with regular porosity. Scaffold are used successfully in various fields of tissue engineering such as bone formation, periodontal regeneration, repair of nasal and auricular malformations, cartilage development, as artificial corneas, as heart valves, in tendon repair ,in ligament replacement, and in tumors. They also are used in joint pain inflammation, diabetes, heart disease, osteochondrogenesis, and wound dressings. Their application of late has extended to delivery of drugs and genetic materials, including plasmid DNA, at a controlled rate over a long period of time. In addition, the incorporation of drugs (i.e., inflammatory inhibitors and/or antibiotics) into scaffolds may be used to prevent infection after surgery and other disease for longer duration. Scaffold also can be used to provide adequate signals (e.g., through the use of adhesion peptides and growth factors) to the cells, to induce and maintain them in their desired differentiation stage, and to maintain their survival and growth. The present review gives a detailed account of the need for the development of scaffolds along with the materials used and techniques adopted to manufacture scaffolds for tissue engineering and for prolonged drug delivery.

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Review Paper: critical issues in tissue engineering: biomaterials, cell sources, angiogenesis, and drug delivery systems

Naderi H, Matin MM, Bahrami AR.

Department of Biology, Ferdowsi University of Mashhad, Mashhad, Iran.

Abstract

Tissue engineering is a newly emerging biomedical technology, which aids and increases the repair and regeneration of deficient and injured tissues. It employs the principles from the fields of materials science, cell biology, transplantation, and engineering in an effort to treat or replace damaged tissues. Tissue engineering and development of complex tissues or organs, such as heart, muscle, kidney, liver, and lung, are still a distant milestone in twenty-first century. Generally, there are four main challenges in tissue engineering which need optimization. These include biomaterials, cell sources, vascularization of engineered tissues, and design of drug delivery systems. Biomaterials and cell sources should be specific for the engineering of each tissue or organ. On the other hand, angiogenesis is required not only for the treatment of a variety of ischemic conditions, but it is also a critical component of virtually all tissue-engineering strategies. Therefore, controlling the dose, location, and duration of releasing angiogenic factors via polymeric delivery systems, in order to ultimately better mimic the stem cell niche through scaffolds, will dictate the utility of a variety of biomaterials in tissue regeneration. This review focuses on the use of polymeric vehicles that are made of synthetic and/or natural biomaterials as scaffolds for three-dimensional cell cultures and for locally delivering the inductive growth factors in various formats to provide a method of controlled, localized delivery for the desired time frame and for vascularized tissue-engineering therapies.

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Tissue Engineering and Regenerative Medicine: History, Progress, and Challenges

François Berthiaume,¹ Timothy J. Maguire,¹ and Martin L. Yarmush1,^2
1Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854; email: ireis [at] sbi.org
²Center for Engineering in Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114

The past three decades have seen the emergence of an endeavor called tissue engineering and regenerative medicine in which scientists, engineers, and physicians apply tools from a variety of fields to construct biological substitutes that can mimic tissues for diagnostic and research purposes and can replace (or help regenerate) diseased and injured tissues. A significant portion of this effort has been translated to actual therapies, especially in the areas of skin replacement and, to a lesser extent, cartilage repair. A good amount of thoughtful work has also yielded prototypes of other tissue substitutes such as nerve conduits, blood vessels, liver, and even heart. Forward movement to clinical product, however, has been slow. Another offshoot of these efforts has been the incorporation of some new exciting technologies (e.g., microfabrication, 3D printing) that may enable future breakthroughs. In this review we highlight the modest beginnings of the field and then describe three application examples that are in various stages of development, ranging from relatively mature (skin) to ongoing proof-of-concept (cartilage) to early stage (liver). We then discuss some of the major issues that limit the development of complex tissues, some of which are fundamentals-based, whereas others stem from the needs of the end users.

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