Hydrogels for tissue engineering.

https://yunus.hacettepe.edu.tr/~damlacetin/kmu407/index_dosyalar/4.%20makale.pdf

Biodegradable polymers as biomaterials

s, and 360 patents, and edited 12 books. He has also received over 80 major awards including the Gairdner Foundation International Award, Lemelson-MIT prize, ACS’s Applied Polymer Science and Polymer Chemistry Awards, AICHE’s Professional Progress, Bioengineering, Walker and Stine Materials Science and Engineering Awards. In 1989, Dr. Langer was elected to the Institute of Medicine of the National Academy of Sciences, and in 1992 he was elected to both the National Academy of Engineering and the National Academy of Sciences. He is the only active member of all three National Academies. Kevin Shakesheff was born in Ashington, Northumberland, U.K., in 1969. He received his Bacheclor of Pharmacy degree from the University of Nottingham in 1991 and a Ph.D. from the same institution in 1995. In 1996 he became a NATO Postdoctoral Fellow at MIT, Department of Chemical Engineering. He is currently an EPSRC Advanced Fellow at the School of Pharmaceutical Sciences, The University of Nottingham. His research group investigates new methods of engineering polymer surfaces and the application of these engineered materials in drug delivery and tissue engineering. 3182 Chemical Reviews, 1999, Vol. 99, No. 11 Uhrich et al.

Polymeric Systems for Controlled Drug Release

Although several major progresses have been introduced in the field of bone regenerative medicine during the years, current therapies, such as bone grafts, still have many limitations. Moreover, and in spite of the fact that material science technology has resulted in clear improvements in the field of bone substitution medicine, no adequate bone substitute has been developed and hence large bone defects/injuries still represent a major challenge for orthopaedic and reconstructive surgeons. It is in this context that TE has been emerging as a valid approach to the current therapies for bone regeneration/substitution. In contrast to classic biomaterial approach, TE is based on the understanding of tissue formation and regeneration, and aims to induce new functional tissues, rather than just to implant new spare parts. The present review pretends to give an exhaustive overview on all components needed for making bone tissue engineering a successful therapy. It begins by giving the reader a brief background on bone biology, followed by an exhaustive description of all the relevant components on bone TE, going from materials to scaffolds and from cells to tissue engineering strategies, that will lead to "engineered" bone. Scaffolds processed by using a methodology based on extrusion with blowing agents.

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Bone Tissue Engineering: State of the Art and Future Trends

This paper reviews biodegradable synthetic polymers focusing on their potential in tissue engineering applications. The major classes of polymers are briefly discussed with regard to synthesis, properties and biodegradability, and known degradation modes and products are indicated based on studies reported in the literature. A vast majority of biodegradable polymers studied belongs to the polyester family, which includes polyglycolides and polylactides. Some disadvantages of these polymers in tissue engineering applications are their poor biocompatibility, release of acidic degradation products, poor processability and loss of mechanical properties very early during degradation. Other degradable polymers such as polyorthoesters, polyanhydrides, polyphosphazenes, and polyurethanes are also discussed and their advantages and disadvantages summarised. With advancements in tissue engineering it has become necessary to develop polymers that meet more demanding requirements. Recent work has focused on developing injectable polymer compositions based on poly (propylene fumarate) and poly (anhydrides) to meet these requirements in orthopaedic tissue engineering. Polyurethanes have received recent attention for development of degradable polymers because of their great potential in tailoring polymer structure to achieve mechanical properties and biodegradability to suit a variety of applications.

/pdf/biodegradable-synthetic-polymers-for-tissue-engineering-34594ikwkg.pdf

Biodegradable synthetic polymers for tissue engineering

The hydrolytically unstable polyphosphazenes, poly [(imidazolyl) (methylphenoxy) phosphazenes] and poly [ethyl glycinato) (methylphenoxy) phosphazenes], were studied as potential polymeric supports for cells in tissue regeneration. For bone repair, their specific function would be to support osteoblast growth, forming a bone-polymer matrix. MC3T3-E1 cells (an osteogenic cell line) were seeded onto polymer matrices and cell adhesion and growth as well as polymer degradation were examined. Both imidazolyl- and ethyl glycinato-substituted polyphosphazenes supported the growth of MC3T3-E1 cells. An increase in the content of the imidazolyl side group resulted in a reduction in cell attachment and growth on the polymer surface and an increase in the rate of degradation of the polymer. In contrast, substitution with the ethyl glycinato group favored increased cell adhesion and growth and also an increase in the rate of degradation of the polymers. Thus, the polyphosphazenes represent a system whereby cell growth and degradation can be modulated by varying the nature of the hydrolytically unstable side chain. This in vitro evaluation suggests that the polyphosphazenes may be suitable candidate biomaterials for the construction of a cell-polymer matrix for tissue regeneration.

Use of polyphosphazenes for skeletal tissue regeneration

Fifteen different poly[(amino acid ester)phosphazenes] [N=P(NHCHRCOOR') 2 ] n (R= H, Me, iPr, Bz; R'= Me, Et, tBu, Bz) were synthesized by treatment of poly(dichlorophosphazene) with a large excess of the appropriate amino acid ester. Several of these polymers were crystalline as measured by DSC. Hydrolysis studies were performed to estimate the rates of decomposition of the polymers and the duration over which the polymers maintained their structural integrity

Poly[(amino acid ester)phosphazenes]: Synthesis, Crystallinity, and Hydrolytic Sensitivity in Solution and the Solid State

Poly[(amino acid ester)phosphazenes] as substrates for the controlled release of small molecules

Poly[bis-(ethylglycolato)phosphazene], poly[bis(ethyl lactato)phosphazene], poly[bi(benzylglycolato)phosphazene], and poly[bis(benzyl lactato)phosphazene] were synthesized. The benzyl esters of glycolic and lactic acid were prepared by the base-catalyzed transterification of their ethyl esters with benzyl alcohol at 90°C. Poly(dichlorophosphazene) was treated with a large excess of the appropriate sodium acid ester at 50°C to yield the fully-substituted polymer. The hydrolytic decomposition profiles of these polymers in aqueous media were monitored by NMR

Synthesis of poly(orgnaophosphazenes) with glycolic acid ester and lactic acid ester side groups: prototypes for new bioerodible polymers

Poly[bis(methoryethoxy)phosphazene], poly[bi[(aminoethory)ethory]phosphazene],poly[bis[(methoryethoxy)- ethoxy]phosphazene], poly[bis[(ethoryethory)ethory]phosphazene], and poly[bis[(butoryethoxy)ethoxy]phosphazene] were synthesized for studies of their water solubility as well as the swellabilities of their corresponding hydrogels in aqueous media. Lower critical solution temperatures (LCST) were detected for four of the polymers. Hydrogels of these polymers were prepared by γ irradiation. The crosslinked polyphosphazenes behaved in a similar manner to that of their soluble counterpart

Shawn R. Pucher

Papers

Use of polyphosphazenes for skeletal tissue regeneration

Poly[(amino acid ester)phosphazenes]: Synthesis, Crystallinity, and Hydrolytic Sensitivity in Solution and the Solid State

Poly[(amino acid ester)phosphazenes] as substrates for the controlled release of small molecules

Synthesis of poly(orgnaophosphazenes) with glycolic acid ester and lactic acid ester side groups: prototypes for new bioerodible polymers

Poly(organophosphazenes) with poly(alkyl ether) side groups: a study of their water solubility and the swelling characteristics of their hydrogels